(Topic ID: 140784)

TerryB's Soldering Guide

By terryb

6 years ago


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    #101 6 years ago

    Temperature Management

    Dwell time, or the amount of time you are applying heat to the joint, is as important as the soldering tip temperature. Electronic components are generally designed to handle 650° for 10 seconds. That's about twice as much time as you should need to solder a joint, so how do components get blown by overheating?

    Other than bad soldering habits, the most common cause is the pins being soldered sequentially. If you use a temperature of 650°, take 5 seconds per lead and solder pin 1, then pin 2 and then pin 3, you have just applied 650° to the individual NOR gate for 15 seconds.

    7402-Chip.gif

    To avoid this you should always alternate pins rather than soldering them sequentially. Start with pin 1 and solder all of the odd pins then start over at pin 2 and solder the even pins. Note that not all IC's have the same internal connections so rather than checking the datasheet for each and adapting the technique, is is generally accepted that alternating pins is a reasonable compromise.

    #102 6 years ago

    Pre-Inspection

    Either after desoldering or before soldering you need to inspect the pads, through-holes and traces. There is nothing worse than installing a new IC and then finding out you had a blown-out through-hole, and now need to remove the IC again. Part of the inspection we'll do visually and part of it with a meter.

    I usually start with a visual inspection using a magnifier. The reason to do a visual inspection instead of just ringing out the board (checking continuity) is that there can be damaged areas that have continuity but need to be repaired. In the image below I've marked some, but not all, of the damage to traces, pads and through-holes.

    Board-Damage-Examples.png

    In the following image you can see where corrosion has started underneath the trace. If you ran your finger across it you would be able to feel where the bubbling in the trace. This would most likely test good with a meter.

    Circuit-Board-Corrosion.jpg

    The next step is to check through-board and across board connectivity. With your meter set in diode/continuity place a lead on the bottom and top side of each through-hole and check. Do not insert the test lead into the through-hole since you can get false good readings even though part of the through-hole is damaged. After that check the traces for continuity from each pad/through-hole to the next connection point. You need to do this for both sides of the board.

    Across-Board-Continuity.jpg

    It's often easier to follow the traces if you back-light the circuit board.

    Backlit-Circuit-Board.gif

    #103 6 years ago

    Equipment Review

    For the next few posts some of the information has been previously covered so I will only lightly touch on some issues. We'll start with a quick equipment review.

    1. Soldering station
    2. Tip sized appropriately for the job
    3. Fiberglass pen and flux (latter optional)
    4. Smaller diameter solder
    5. Polyimide tape
    6. Side cutters
    7. Flux cleaner/Naptha/Alcohol
    8. Magnifying glass
    9. Exhaust fan

    Preperation

    Physically clean the pad (both sides of the board) and if you still have oxidation or are new to circuit board soldering you may want to add some flux. As mentioned previously you want a good physical connection before soldering--in this case though we're specifically concerned with the joint moving during soldering.

    After installing resistors and capacitors bend the leads over or use some polyimide tape to hold it in position (or both). Rather than bend pins on sockets or IC's I just use the polyimide tape.

    Bend-Resistor-Leads.jpg

    Whether you install a socket or not is up to you. I use sockets on high-failure IC's (lamp and switch matrix, etc.) and for low-failure chips (some random IC on the audio board) I typically do not use sockets. If you have done any repair to pads, through-holes or traces you definitely want to use a socket so the joint does not need to be heated in the future should the chip fail again.

    There are those who suggest you should always trim the leads before soldering or you risk damaging the joint. As long as you clip the lead slightly above the solder (1/16" is fine) my opinion is that trimming after soldering is fine, although I will admit that trimming before would be considered best practices.

    I usually solder with the board flat on my ESD mat, but if you prefer using some type of board clamp that's fine. In any case make sure the board is stable. Other than a few cases, which we'll discuss in the advanced soldering section, you should solder from the non-component side of the board.

    #104 6 years ago

    Soldering

    Finally, we're ready to do some circuit board soldering. Set your temperature controlled iron to your preferred setting and let it come up to temperature (give it another 5 minutes after it reaches temperature).

    In some cases I have adapted standard soldering/desoldering techniques slightly since we're dealing with twenty some year-old boards and lifting a trace/pad or blowing out a through-hole is more likely to occur. At this point we're purely talking about resistors, small capacitors and IC's, we'll cover larger components later.

    Before soldering always clean and tin the soldering tip. Apply some solder to both sides and then wipe the tip on a copper sponge. Clean the tip fairly frequently while soldering to remove excess solder and oxidation. Any time you put the iron back in the holder, flush the tip with solder.

    At this point you can add some flux to the joint(s) if you so desire.

    It is critical to place the iron's tip properly to achieve maximum surface contact between the tip and the land and the lead (the tip must touch both the land and the lead). The iron should be held at about a 30° angle to the board when using a chisel tip. Although you can have too much surface contact, so do not place the flat side of the chisel tip on the land, as this may cause it to lift.

    Soldering-Technique-1.gif

    While we have maximized contact between the iron, the land and the lead we still need to improve heat transfer by forming a solder bridge. After the joint has pre-heated for 1-2 seconds (small components), briefly touch the solder to the tip where it meets the joint (from the opposite side). This will form a solder bridge and provide a much larger, and effective, area for heat transfer from the soldering iron to the joint.

    Soldering-Technique-2.gif

    Once the solder begins to melt, which should happen almost immediately, move the solder to the opposite side of the joint. The solder will flow towards the heat source.

    Soldering-Technique-3.gif

    As you add solder it will form a convex ball and when the solder begins to flow the surface of the ball will briefly, and quickly, shrink (as the solder flows through to the other side of the board) and become slightly concave. Once the solder is flowing, add a little more solder until you have good coverage and remove the solder from the joint prior to removing the iron.

    As you get more experienced you will learn that at this point you need to add another 1/2" of solder, for example, or feed solder for 1-2 more seconds (example again). Once you get the hang of this you will be able to move from joint to joint fairly quickly.

    Soldering-Technique-4.gif

    Total time on joint should be from 3-5 seconds for small components.

    #105 6 years ago

    Much thanks to zaza for improving my tip size image in post 4.

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1#post-2725138

    #106 6 years ago

    Those are good prices but I don't need 1 pound when I rarely solder although I may end up doing more soldering for the fun of it. I used to have a Weller soldering gun.

    I did a personal mod on an EM with the soldering gun, soldering added wires, switches and jones plug. Will have examine them to see how they look today. (I didn't know to clean the flux at that time)

    Quoted from terryb:

    Yes you can use it with lead-free solder, but I would just stick with the lead solder. Lead-free is harder to work with, you need to use a lot of added flux and it has a rough looking surface when soldered so it's hard to inspect for a good joint. See the second image in the following link.
    https://www.quora.com/What-are-the-disadvantages-of-lead-free-solder-vs-lead-solder

    Okay. How about this one? Will it be enough to unsolder a few pop bumpers?

    amazon.com link »

    BTW, do you plan to make a soldering video and link it here?

    #107 6 years ago
    Quoted from PinballFever:

    Okay. How about this one? Will it be enough to unsolder a few pop bumpers?

    Good stuff, but I would go with .040 - .060 diameter for playfield work. Surprisingly, using the proper size solder makes life so much easier.

    I will be posting a soldering video in a few posts (not mine, but from a friend).

    #108 6 years ago

    Thanks again to zaza for providing a great 3D view of a through-hole (instead of my crappy 2D one).

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1/page/2#post-2739824

    #109 6 years ago

    Soldering Continued

    The following image shows what a good joint should look like. After moving the solder to the opposite side of the joint you will get something that looks similar to the top right image. When the solder flows through the board you will start to get a concave shape like the middle bottom image. Add a little more solder and your joint should look like the upper left image.

    Solder-Joints.gif

    If you use a larger diameter solder you will fill the joint before the solder flows and end up with a cold solder joint. You want to use a small diameter solder (.031") and feed it at a moderate pace. You should be able to see the transition as the solder flows and the solder joint becomes concave. If you do not then your solder diameter is too large or you're feeding it too quickly.

    So while fast is better--since you're reducing the chances of damaging the board--too fast is also bad. If you're on and off the joint too quickly the solder will not get a chance to flow and you will get a cold solder joint.

    When soldering through-holes flip the board over and make sure the solder has adequately flowed through the board. If it has not, heat the joint for a few seconds and apply a little more solder. Once you get more experienced at feeding solder (either based on time or how much solder you've added) you will not need to do this on every joint.

    Through-Hole-Solder-Fillet.jpg

    Continue soldering any additional joints.

    Once you're done, let the joints cool before continuing--if moved while warm you can end up with a cold solder joint. Do not use compressed air, flux or anything else to cool the joint faster. Clip the leads off slightly above the solder with side-cutters and then clean the area with flux remover/Naptha/Alcohol.

    When you're done for the day clean the tip with your copper sponge, flood it with solder and reduce the temperature to 482°. Clean the tip with a damp sponge and tin it again. Turn off the iron and get ready to... inspect your work.

    #110 6 years ago

    Inspection

    Use a magnifying lens and good lighting for the visual inspection. The solder joint should be shiny and smooth, slightly concave and have no pits, sharp edges or deep scratches. Here's a few common problems and their likely causes.

    Disturbed Joint: The joint was subjected to movement before the solder was cool. A disturbed joint will be frosted, crystalline or rough.

    Disturbed-Joint.jpg

    Disturbed Joint: Note how the solder has not adhered properly to the lead. In this case the lead was likely trimmed before the solder was cool. Also note the leads were not cut above the level of the solder, this also contributed to the problem. It is also likely that heat was not applied to the lead.

    Disturbed-Joint-2.jpg

    Cold Joint: A cold joint is caused when the solder did not melt completely and is characterized by a rough or lumpy surface. This can be caused by iron temperature too low, joint not pre-heated sufficiently or heat removed from the joint too soon.

    Cold-Joint.jpg

    Poor Wetting, Pad: Both of these joints show signs of insufficient wetting of the solder pad. The leads are wetted nicely, but the solder has not formed a good bond with the pad. Either heat was not applied to the pad or the pad was dirty/oxidized.

    Poor-Wetting-Pad.jpg

    Poor Wetting, Lead: In this case the lead has not wetted at all and the pad is only partially wetted. Most likely heat was not applied to the lead and not enough solder was added to the joint.

    Poor-Wetting-Pin.jpg

    The concave shape of the solder fillet is an important indicator that wetting has occurred. Compare a properly soldered joint (below) to the convex shape of the previous images. When inspecting your work this is critical indicator of a good joint.

    Wetting-Angle.gif

    For the technical geeks out there here's an IPC guide on through-hole solder joint evaluation. Note: IPC (Institue for Printed Circuits) is the generally accepted standard for printed circuit board rework.

    IPC Through-Hole Solder Joint Evaluation

    #111 6 years ago

    Soldering Video

    Here's an excellent soldering video from my friends at the CuriousInventor. Some of the information will be redundant, but is still worth reviewing. You will note there are some small differences between their recommendations and mine, and that's pretty normal. Soldering is one of those things where you definitely find your groove as you gain experience and small variations in technique are fairly common.

    At the point in the video where they are soldering an IC and it is filmed at 1/4 speed you can see the solder shrink and flow through the board. Identifying when flow occurs is important because that is your starting point for adding additional solder to get a good joint on both sides of the board.

    Two other points on the video. While there are times that a heat-sink is recommended on highly-heat sensitive components I have never found this necessary in pinball repair. Also a heat-sink makes soldering more difficult since it draws heat away from the joint.

    In the video they add a small amount of solder to the tip before pre-heating each joint briefly (about one second) and then add solder to form a solder bridge. My preference is to not add solder to the tip before applying it to the joint although I will pre-heat the first joint slightly longer (about two seconds). As you move on to the second joint though there will be some solder on the tip and you will not need to pre-heat as long (about one second). So the techniques are not as dissimilar as they might initially seem, and either technique will work just fine.

    #112 6 years ago
    Quoted from terryb:

    Good stuff, but I would go with .040 - .060 diameter for playfield work. Surprisingly, using the proper size solder makes life so much easier.
    I will be posting a soldering video in a few posts (not mine, but from a friend).

    Where do you find the Henkel .40-.60 solder? My web search is only showing .31 and not the thicker stuff you mentioned above.

    Thanks!

    #113 6 years ago

    There's a link for Kester here (it's good stuff also, and I wouldn't waste the money on multicore for playfield work).

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1/page/2#post-2740392

    #114 6 years ago

    Good info here - specifically the temperatures post. Thanks for taking the time to post.

    Chris

    #115 6 years ago
    Quoted from gdogfunk:

    Where do you find the Henkel .40-.60 solder?

    Terry,

    I'm not finding anything at that link but i did a google search for "kester rosin core solder" and found this one that seems to be .60.

    Does this look like the right solder for my need?

    http://www.neobits.com/kester_solder_24_6040_0061_44_rosin_core_solder_60_p2761001.html?atc=gbp&gclid=Cj0KEQjwwIKxBRDKhOz7ytT30vkBEiQAT1NaPdAYEi5KbdFoLXp2BM9XJ6cOEamEuaFnEeItrtbMVS4aAq1Q8P8HAQ

    Thanks,
    Bruce

    #116 6 years ago
    Quoted from PinballFever:

    Does this look like the right solder for my need?

    That looks fine, and that's a good price.

    #117 6 years ago
    Quoted from terryb:

    That looks fine, and that's a good price.

    Okay. Thanks again.
    Bruce

    #118 6 years ago
    Quoted from PinballFever:

    I'm not finding anything at that link

    Here are the Stanley and Kimco links from that link, not sure why it wasn't working for you:
    .062":
    Kimco: http://gokimco.com/44-rosin-core-solder-wire-sn63-pb37-062-66.html
    Stanley: http://www.stanleysupplyservices.com/kester-24-6337-0061-63-37-44-rosin-core-solder-062-diameter/p/111-303

    #119 6 years ago
    Quoted from fosaisu:

    Here are the Stanley and Kimco links from that link

    Thanks for the links. Much appreciated!

    Bruce

    #120 6 years ago

    I edited the soldering video post to better explain the slight difference in technique between the video and what I have presented (both are acceptable techniques).

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1/page/3#post-2745934

    #121 6 years ago

    Hakko now has an optional rubber cleaner (B3474) for the Hakko FX-888D and the FH-800 iron holder (may have been around for a while and I just missed it). I have not tried this yet, but it sounds like a good idea for $5.

    FH-800.gif

    #122 6 years ago

    Since the video has not received any feedback, I would like to know if it was sufficient or you would like to see one that's a little more in-depth (although the soldering technique is not quite as good). It's really hard to find good soldering/desoldering videos.

    #123 6 years ago

    I actually saw that video earlier this year when I was getting back up to speed on soldering. I thought it helped a lot since I hadn't soldered a circuit board in years. I bought a couple of small Radio Shack kits and got my feet wet again before attempting to repair my pin. Today, I ran into one of the problems you mention above regarding damage to a pad/land. In my Medusa aux lamp driver board, the middle pad for an SCR appears to be no longer there, but I was able to make a solder joint that appears to work in test mode with an alligator clip on the ground braid and touching the SCR. But in-game, the lamp won't light. Does that sound like a problem of the bad pad and if so, will you be covering trace/pad repair?

    #124 6 years ago
    Quoted from gdogfunk:

    Does that sound like a problem of the bad pad and if so, will you be covering trace/pad repair?

    That would be my guess and yes I'll be covering a couple of options for trace/pad repair. I've seen cases where a through-hole is destroyed and the circuit will work if you press down on the IC. So the differences between game play and testing could be affecting the result.

    #125 6 years ago

    High Heat Dissipation

    One thing you'll notice when soldering an IC is that some pins are a little harder to solder than others. This is common on ground and some Vcc (supply voltage) pins and is caused by larger traces which draw heat away from the joint. In this case all you typically need to do is give it a little more time between steps (pre-heat for a second longer and/or give it a second after forming the solder bridge before moving the solder to the opposite side of the joint).

    You should still be able to solder the joint within 3-5 seconds and at your preferred temperature (650° in my case).

    Ground-Trace.jpg

    This issue is magnified when dealing with bridge rectifiers and large capacitors and transistors. As covered before, your tip should be properly sized for the pad, which will be larger than the pads on small components. So you'll want to go to a .125" or .187-.200" tip.

    Some manufacturers offer high-capacity (temperature) tips, which perform better with large components/traces. In the case of the Hakko FX-888D the .125" T18-DL32 tip is high-capacity (as indicated by the L). Although the .200" (T18-S3) is not labeled as high-capacity the shape and size of the tip would indicate that it is.

    As above, just add a second or two between steps. Adding some additional flux is a good idea and has no downside.

    If you're still having trouble then add a small amount of the solder to the tip before pre-heating the joint (as shown in the video above). If you're still having trouble then increase the soldering iron temperature (maybe 700°). You'll learn over time that on some large components with large traces you will automatically go to a higher temperature. As long as your dwell time is in the range of 5-8 seconds there won't be a problem with the increased temperature.

    Bridge-Rectifier-Trace.jpg

    Ground-planes can be the most troublesome to work with, although they are not all created equally. Below is a picture of a patterned ground-plane on a WPC board. The pattern reduces the flow of heat away from the joint and generally these are not too difficult to solder with your standard technique.

    Patterned-Ground-Plane-1.jpg

    On some older boards there are very large ground-planes which can be a challenge to solder. Follow the steps above and you may want to increase your temperature up to 750°. This is definitely a case where the high-capacity tip and adding a little solder to the tip before pre-heating will help a lot.

    Your dwell time will be longer than previously discussed, but the ground-plane is unlikely to lift unless it is already damaged. Keep in mind that at 850° you can start to get lead included in the vapor.

    Ground-Plane-2.jpg

    Thanks to barakandl for the image.

    #126 6 years ago
    Quoted from terryb:

    High Heat Dissipation
    One thing you'll notice when soldering an IC is that some pins are a little harder to solder than others. This is common on ground and some Vcc (supply voltage) pins and is caused by larger traces which draw heat away from the joint. In this case all you typically need to do is pre-heat the joint a little longer or give it another second after forming the solder bridge before moving the solder to the opposite side of the joint.
    You should still be able to solder the joint within 3-5 seconds.

    This issue is magnified when dealing with bridge rectifiers and large capacitors and transistors. As covered before, your tip should be properly sized for the pad, which will be larger than the pads on small components. So you'll want to go to a .125" or .187-.200" tip.
    In some cases high-capacity (temperature) tips are available, which perform better with large components/traces. In the case of the Hakko FX-888D the .125" T18-DL32 tip is high-capacity (as indicated by the L). Although the .200" (T18-S3) is not labeled as high-capacity the shape and size of the tip would indicate that it is. If you have the T18-D32 it is perfectly fine, but next time you need a new .125" tip I would order the T18-DL32.
    Depending on the configuration, you may need to pre-heat the joint for 1-2 seconds longer and give it another 1-2 seconds after forming the solder bridge before moving the solder to the opposite side of the joint. Adding some additional flux is a good idea and has no downside.
    If you're still having trouble then add a small amount of the solder to the tip before pre-heating the joint (as shown in the video above). If you're still having trouble then increase the soldering iron temperature to 700 degrees. You'll learn over time that on some large components with large traces you will automatically go to 700 degrees. As long as your dwell time is in the range of 5-8 seconds there won't be a problem with the increased temperature.

    I push 700 frequently.... 800 even. but i try and work fast. Unless you have a monster sized tip, the hakko fx888 is going to need to be at 800+ to melt solder on .156" headers for a Williams driver board on the ground plane or other earlier boards that have massive, un patterned ground planes. I would say if you have trouble getting solder to melt for a bridge rectifer or header pins after a few seconds, It is okay to raise the heat. You want it to flow not bubble up around the post.

    #127 6 years ago
    Quoted from barakandl:

    I push 700 frequently.... 800 even. but i try and work fast. Unless you have a monster sized tip, the hakko fx888 is going to need to be at 800+ to melt solder on .156" headers for a Williams driver board on the ground plane or other earlier boards that have massive, un patterned ground planes. I would say if you have trouble getting solder to melt for a bridge rectifer or header pins after a few seconds, It is okay to raise the heat. You want it to flow not bubble up around the post.

    I agree. I guess my point is that people should not immediately think that a higher temperature is the solution when they're having trouble. I've seen too many people use temperature to make up for poor soldering technique, or equipment, or the wrong tip size. First you need to cover the basics and then increase the temperature when needed.

    Just curious, have you tried the Hakko high-capacity tips, and if so have you seen any difference in temperature requirements?

    High-Capacity-Tip-2.gif

    22 degrees Celsius == 70 degrees Fahrenheit.

    #128 6 years ago
    Quoted from terryb:

    I agree. I guess my point is that people should not immediately think that a higher temperature is the solution when they're having trouble. I've seen too many people use temperature to make up for poor soldering technique, or equipment, or the wrong tip size. First you need to cover the basics and then increase the temperature when needed.
    Just curious, have you tried the Hakko high-capacity tips, and if so have you seen any difference in temperature requirements?
    High-Capacity-Tip-2.gif
    22 degrees Celsius == 70 degrees Fahrenheit.

    I have not tried any high capacity tips. I actually always use the same tip size for the most part to keep things simple. A nice average size chisel i do SMT to big fat rectifiers with.

    When you are trying to melt this kind of stuff on early boards is when i crank the heat up 800+. Otherwise much lower. Newer boards never need much more than 750f as the ground areas will have a checkered pattern typically.

    20151018_230028.jpg

    #129 6 years ago
    Quoted from barakandl:

    I have not tried any high capacity tips. I actually always use the same tip size for the most part to keep things simple. A nice average size chisel i do SMT to big fat rectifiers with.

    As people become more experienced they develop their own techniques, and that's fine because they are based on experience. You can look at a board and know what you can get away with and what you can't, but a beginner/intermediate can't. You understand the nuances such as "I'm unlikely to lift a ground-plane" or "not all ground-planes are created equally" but others don't. Unfortunately it's not possible to cover every possibility or teach experience so I stick with best practices and as people gain experience they can adapt the technique to their own preferences.

    Beginner/intermediates should use the proper tip size and a high-capacity tip when doing large components/traces. This will dramatically improve their margin of error. As they get better then they can do whatever they want, but they'll get there with a lot less frustration and less damaged boards with the lower temperature. I've never had to go over 750 degrees on a board in my life (and trust me, a board from an X-Ray machine has a lot larger ground plane than any pinball board I've ever seen), but I use the proper sized tip and when appropriate a high-capacity tip (70 degree swing, plus whatever the proper size tip gives you, makes a pretty big difference).

    Again, nothing wrong with your approach, but not what I would advise beginner/intermediates to do. Good discussion though and it did help me improve my post above (not yet, but I'll edit it tomorrow).

    One other thing I should mention is that above 850 degrees you are going to get lead molecules in the vapor.

    #130 6 years ago
    Quoted from terryb:

    As people become more experienced they develop their own techniques, and that's fine because they are based on experience. You can look at a board and know what you can get away with and what you can't, but a beginner/intermediate can't. You understand the nuances such as "I'm unlikely to lift a ground-plane" or "not all ground-planes are created equally" but others don't. Unfortunately it's not possible to cover every possibility or teach experience so I stick with best practices and as people gain experience they can adapt the technique to their own preferences.
    Beginner/intermediates should use the proper tip size and a high-capacity tip when doing large components/traces. This will dramatically improve their margin of error. As they get better then they can do whatever they want, but they'll get there with a lot less frustration and less damaged boards with the lower temperature is better approach. I've never had to go over 750 degrees on a board in my life (and trust me, a board from an X-Ray machine has a lot larger ground plane than any pinball board I've ever seen), but I use the proper sized tip and when appropriate a high-capacity tip (70 degree swing, plus whatever the proper size tip gives you, makes a pretty big difference).
    Again, nothing wrong with your approach, but not what I would advise beginner/intermediates to do. Good discussion though and it did help me improve my post above (not yet, but I'll edit it tomorrow).
    One other thing I should mention is that above 850 degrees you are going to get lead molecules in the vapor.

    I feel you. It is a heat transfer thing, not really temperature. The solder melts at X temperature. The bigger the trace, the bigger the heatsink. If it was doing it right, you would use three different sized tips on a Williams driver board. One for ICs and small components, one for normal headers and solenoid transistors, and a third huge one for the ground supply voltage headers. For me... i am trying to get paid doing board work, so I crunch time whenever possible. Changing tips takes time on the FX888 as you really should let it cool down.

    The other thing I have been known to do when desoldering this stuff is to double hand it. I use the pen iron in one hand the vac gun in the other to be able to transfer enough heat to cleanly melt the solder around the ground headers without pushing temperature too high. That is a more advanced technique though.

    Everything i do is self taught, so I probably do it wrong =D

    #131 6 years ago
    Quoted from barakandl:

    Everything i do is self taught, so I probably do it wrong =D

    Nothing wrong in your approach, you're working in a production environment and swapping tips takes time. Most other people aren't under time pressure and should use the correct tip, especially when they're learning. It's not feasible for someone repairing pinball circuit boards, but that's why repair/rework facilities use multi-channel stations. They don't change tips, they grab another iron/gun. Time is money.

    As I said before, I'm glad to have the conversation, the end result is more definitive information.

    To be honest, I though I'd put everyone to sleep.

    #132 6 years ago

    Added information in the following post on ground-planes.

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1/page/3#post-2749321

    Quoted from terryb:

    Since the video has not received any feedback, I would like to know if it was sufficient or you would like to see one that's a little more in-depth (although the soldering technique is not quite as good).

    Haven't heard anything so I'll presume everyone is happy with the video above.

    #133 6 years ago

    Re-Flowing Solder

    First let's talk about why you are re-flowing solder. In the first image below there's a crack around the lead and in the second image the crack is a little farther out in the joint. Either of these can be caused by vibration or the solder joint was cold to start with but worked (for a while). When inspecting joints you should be using that magnifying lens we talked about earlier.

    Cracked-Solder-Joint.jpg

    Cracked-Solder-Joints.jpg

    The first question you need to ask before re-flowing solder is if the joint has the correct amount of solder or is on the low side. This will affect the technique you use.

    Solder-Amount.png

    No matter which technique you use the first step is to mechanically clean the joint with a fiberglass pen. Then you want to add some flux to each joint. Even if we are adding solder, it won't be enough to properly clean the joint.

    First we'll cover a joint that has sufficient solder. Place the tip of your iron just as you would if soldering a joint. As the solder melts move the tip in to until it is making contact with both the pad and the lead. As the existing solder melts it will create a solder bridge. Give it 2-3 seconds to ensure proper wetting. Clean up your flux and you're done.

    If the joint does not have sufficient solder we will have to create a solder bridge (this is basically the same process as soldering a fresh joint). Place your iron against the joint and as the solder melts, move the tip in until you are touching the pad and the lead. Pre-heat for 1-2 seconds and then add a small amount of solder at the junction of the tip and joint. Move the solder to the opposite side of the pad and feed a little more solder (won't take much). Make sure the solder has wetted and remove the solder and then the tip. Clean up your flux residue.

    Pro Tip

    A hot air gun works great for re-flowing solder on connectors--especially ones where there are a lot of pins, like ribbon cables. Put some flux on all of the joints and then heat with the hot air gun until the solder flows. In most other cases where you're just dealing with a couple of leads it's faster just to use a soldering iron. You also want to be careful using a hot air gun around chips since the package can be damaged by the heat.

    #134 6 years ago

    Intermediate Desoldering

    I mentioned this previously, but it's worth saying twice. Ninety percent of the damage done to pinball circuit boards is done while desoldering, and the majority of that occurs when a component is pried off the board while there is still some adhesion between the lead and the pad/through-hole.

    Note: Rather than constantly saying pad and/or through-hole I will use either land or pad to cover both. If there is a difference that is specific to through-holes or pads I will make that clear.

    It is not at all uncommon for a little bit of solder to remain behind and adhere the lead to the pad. This small amount of solder is normally not visible (especially on a through-hole) and therefore each lead, on a chip for example, needs to be tested mechanically. For lack of a better phrase, I'll call this contact adhesion since the solder will adhere the lead to the pad, or though-hole, at the point where they are touching. This can occur even when using a desoldering gun, although with the proper technique it is less likely.

    The first step in de-soldering is often soldering. It is common for these old boards to have very little solder on the joint (often much less than the "not enough solder" example shown in post 140 below). This makes it impossible to get a good solder bridge for heat transfer. I would say that more than half the time I need to add solder to a joint before de-soldering.

    Unlike the soldering section I'm going to offer several approaches to desoldering. Which one you choose is based on available equipment, soldering experience, condition of the board (remember those high-risk boards) and personal preference. As I did previously with soldering we'll start out with small components and then move on to larger components, which are more difficult to desolder. I will cover the various approaches first and then provide more in-depth information on using solder wick, a solder sucker or a desoldering gun.

    Cutting Leads

    This approach is appropriate for those new to desoldering and will almost guarantee that you don't do any damage to the board. Normally it is used with IC's as compared to other small components. In the case of resistors and capacitors it is easier to verify there is no contact adhesion before removing the component.

    This is also a good method for improving your skills and then moving on to removing components without cutting the leads. With this approach you will get immediate feedback on whether you have removed all of the solder without the risk of damaging the board by attempting to pull the component.

    Use your side-cutters to clip off each lead of the chip. At this point you can continue by using solder wick, a solder sucker or a desoldering gun (I'll cover each of these options later). There is also one other desoldering technique which is only available when you have first cut the leads, so we'll cover that now. Although this is probably the easiest technique the other's will provide direct feedback on how your skills are improving.

    Cutting-Leads.jpg

    Physically clean the joint on the non-component side of the board and then apply some flux. Use a board clamp or a 2x4 (as discussed in the equipment section) to hold the board perpendicular to the work surface. Grab the lead with a pair of needle-nose on the component side of the board and heat the pad from the non-component side while gently pulling on the lead. As the solder melts press the tip slightly into the solder bridge. In a couple of seconds the lead will pop right out.

    Desolder-Cutting-Leads.gif

    At this point you can remove the remainder of the solder from the hole using wick, a solder sucker or a desoldering gun. This is actually a case where solder wick works pretty well.

    #135 6 years ago

    Equipment Review

    Depending on the technique you use the equipment needed will vary, so here's an all inclusive list.

    1. Solder wick, solder sucker, desoldering gun
    2. Fiberglass pen and flux
    3. Orangewood sticks and toothpicks or solder picks
    4. Smaller diameter solder
    5. Side cutters
    6. Needle-nose pliers
    7. Flux cleaner/Naptha/Alcohol
    8. Magnifying glass
    9. Exhaust fan

    Preperation

    If you are using a soldering iron with wick or a solder sucker select a tip the same size as the land. The same applies if you're using a desoldering gun.

    Desoldering-Tip-Size.gif

    Pre-heat your soldering iron or gun. I use 650° on the iron and a setting of 2 1/2 on the Hakko 808 (the manufacturer recommends a setting of 3 or 4 for through-hole boards). On the FR-300 Hakko recommends a setting of 2 for though-hole boards. Always clean and tin the desoldering gun nozzle before starting and clean it on your copper sponge frequently while working. Flush the nozzle with solder each time you put the gun back in its holder.

    Note: The potentiometer on the 808 can be easily broken if you try to turn it past the stops on either side. It also does not have a good indicator of where it is currently set so you will have to move it through the range to determine min/max and then set your temperature.

    Mechanically clean the solder joints with a fiberglass pen. Joints should be nice and shiny when you're done. Both desoldering guns and solder suckers require a certain amount of solder mass before they will effectively work. So if you have any pads with low solder add a little before desoldering. At this point you want to add a little flux to all of the joints.

    #136 6 years ago

    Solder Wick

    While it is possible to remove an IC using solder wick, most people will find a solder sucker easier. There are times though when wick is the correct tool. It works well for cleaning up any excess solder if you have cut off the leads and then removed them with pliers. It is also a good choice for removing excess solder from traces and ground planes.

    With solder wick you do not need to add any solder to low joints.

    Place a strip of flux on the first inch of the bottom side of the wick and then place the wick on the joint, overlapping it by about an inch or so. Sometimes more, sometimes less, but you'll figure that out as you gain experience. Apply some solder to your soldering iron tip (this creates a solder bridge and heats the wick/joint up faster). Place the tip on top of the wick at the point where the wick is over the pad. After a couple of seconds the solder should start to flow into the wick.

    Note: Liquid flux works well with solder wick since you can just dip it in the flux.

    As the wick fills with solder, slowly pull it towards you while keeping your tip above the joint (like sliding a piece of cheese from between two pieces of bread while keeping the bread in place--sorry that's the best analogy I can come up with at the moment). This will expose a clean section of wick to the joint and solder should continue to flow to the wick. Continue until done or you've reached the end of the wick. Repeat with a new section of wick if needed.

    If you previously removed the leads and are having trouble getting that last little bit of solder out of the hole, heat the joint and insert a toothpick through the hole.

    Solder-Wick-Board.jpg

    #137 6 years ago
    Quoted from terryb:

    like sliding a piece of cheese from between two pieces of bread while keeping the bread in place

    #138 6 years ago

    I know, the worst analogy in the history of the world. I'm open for suggestions.

    #139 6 years ago

    Solder Sucker

    Clean the joint with a fiberglass pen and add some flux to it. Preheat, clean and tin your soldering iron.

    Position the solder sucker close to the joint, but not on it. Apply the iron's tip to the joint and after a couple of seconds the solder should begin to flow and you can press the tip into the solder bridge. Wait about 1 second after the solder turns liquid and then remove the soldering iron, place the sucker on top of the joint (as flush to the board as possible) and depress the release.

    You need to do this swap fairly quickly. It will feel kind of odd at first, but you will quickly get the hang of doing the swap.

    Solder-Sucker-Board.jpg

    Anytime there is excess solder on the tip of the iron, wipe it off on your copper sponge. Also clear the solder sucker tip after each use. As the tip ages it is not uncommon for solder to work its way between the tip and the plunger. If this happens the sucker will not clear properly and may take a few plunges to clear (disassemble the tip if necessary).

    Repeat as needed until the eye of the lug is clear--usually once or twice total will do it. If you previously cut the leads, they should fall out as you complete each joint. Remember the ground and Vcc leads are often a little more difficult to desolder and you may need to pull them out with pliers or use an orangewood stick.

    The solder sucker requires a certain amount of solder mass to work efficiently so if most of the solder is removed, but the hole is not clear, you may have to add a little solder to the joint.

    If you did not cut the leads then do the following after clearing the holes. Take your orangewood stick and press each lead away from the side it is resting against. This should not take a lot of pressure and will break any contact adhesion. Repeat on the component side of the board. If you are having trouble with a lead you can heat the joint while pushing the lead towards the middle of the hole with the stick.

    Feel free to trim the stick to meet your personal preferences. I like one end with a bevel cut and the other with a perpendicular cut.

    Orangewood-Stick-Chip.jpg

    Yes I know the joints aren't desoldered, it was just the quickest way to get a photo.

    Once all of the leads move freely the chip should pull out easily with your fingers. If not use your orangewood stick to gently pry up the IC. If it does not come out easily you probably still have some contact adhesion.

    #140 6 years ago

    Desoldering Gun

    As mentioned earlier, make sure there is sufficient solder on the joint before desoldering. This is especially critical with a de-soldering gun/station.

    If you did not add solder to the joint, clean the joint with a fiberglass pen and add some flux to it. Select a nozzle that is the same size as the pad and then preheat, clean and tin your nozzle. Clean the nozzle of excess solder frequently while working.

    Surprisingly I see almost as much damage done by people using a desoldering gun as those using other techniques. This is typically caused by insufficient solder on the joint, which leads to pressing the nozzle directly in contact with the land in an attempt to get good heat transfer, or otherwise placing the tip in contact with the pad. The Hakko manual specifically cautions users about this (see second image below).

    Using a desoldering gun does not guarantee success. Even with the Hakko if you pry the chip up while there is still contact adhesion you are going to damage a pad.

    If you have trouble maintaining a gap, slide the end of a toothpick under the nozzle as the solder melts. As you get more experienced you won't need this step. If the pitch of the vacuum changes while desoldering, you are likely pressing the nozzle against the board, which restricts air flow and causes the change in sound.

    Just as with soldering, the most important thing is to create a solder bridge (in this case from the melting solder) which transfers heat more effectively than nozzle to land contact. If the joint is low on solder you will not get a good bridge and should add some solder to the joint before desoldering. It is even OK to add solder to the point where the joint would normally be considered to have too much solder. In fact if you're having difficulty desoldering a component you may find that helps with the process.

    Solder-Amount.png

    Place the nozzle on the joint and once the solder has begins to melt (1-2 seconds), gently swing the nozzle back and forth. Once the lead moves easily, indicating the solder is liquid, press the trigger for 2-3 seconds. On more difficult joints (large traces like ground and Vcc) I may give it a couple of 2 second hits. Remove the nozzle from the joint and continue to press the trigger for a couple of seconds to clear the nozzle.

    Total time on the joint for small components should be around 5 seconds.

    Hakko-808-Desoldering.gif

    The through-hole should be completely free of solder when you're done. Turn the board over and make sure the pad on the component side is also completely free of solder.

    Through-Hole-Desolder.jpg

    In the image below you can see where the right and left leads of the IC still have some solder. If this occurs, repeat the procedure above, but keep in mind you may need to add some solder first. As with the solder sucker, the desoldering gun requires a certain amount of mass to work efficiently.

    If this occurs frequently then you're not getting a good solder bridge (too little solder on joint), the gun temperature is too low or the joint is not being heated long enough before turning on the pump.

    Desolder-Inspection.jpg

    Once the hole is visibly clear take your orangewood stick and press each lead on the non-component side of the board away from the side of the pad it is resting against. This will break any contact adhesion. Repeat on the component side of the board. If you are having trouble with a lead you can heat the joint with a soldering iron while pushing the lead towards the middle of the hole with the stick. The latter approach is also safer, especially on a high-risk board.

    Once you get better at desoldering you can try grabbing the chip with a pair of pliers and rotate it slightly clockwise and counter-clockwise to break the contact adhesion. Not recommended until your skills have improved.

    Once you are positive the leads are all free, gently pry the chip up. Clean up the flux and clean the desoldering gun as described earlier. During long desoldering sessions you may have to perform this cleaning multiple times. If the gun is not cleaned and maintained properly it will dramatically affect performance.

    Pro Tip

    One tool the professionals use to remove contact adhesion on chips they know are troublesome is a hot air rework station or a hot air gun. After removing the solder with a desoldering gun they will use a hot air gun to heat the joints until they can easily remove the chip by pulling on it. You can pick up an Aoyue 8032 hot air gun for about $80. I normally would not recommend Aoyue, but a hot air gun does not require the same quality of design and manufacture as other soldering equipment.

    #141 6 years ago

    Desoldering Video

    Although this video from the gang at CuriousInventor will address a couple of issues I haven't touched on yet, this is a good time to share it. As before you will note some minor variance in techniques. In most cases that's fine, but I will mention a couple of specific issues.

    Keep in mind that most people are not used to dealing with twenty year-old boards, and in the case of the CuriousInventor they are mostly dealing with newer boards.

    1. I think adding solder flux to the wick will make your life much easier. Ditto for the solder sucker and desoldering gun.
    2. His temperature settings are about 50° higher than what I have suggested. I don't have a problem with that, but don't generally think it's necessary if you have proper technique and equipment.
    3. He uses a circular motion with the Hakko. This is fine for round leads, but for flat leads you should use a back and forth motion.
    4. He does not run the pump for a couple of seconds after removing it from the board, which clears the tip of solder.

    I will add another video that covers desoldering guns in more depth.

    #142 6 years ago
    Quoted from terryb:

    Desoldering Gun
    Surprisingly I see almost as much damage done by people using a desoldering gun as those using other techniques. This is typically caused by not clearing all contact adhesion prior to removing the component or placing the nozzle directly in contact with the land. The Hakko manual specifically cautions users about this latter issue (see image below).
    .

    Damn, I learn something here. I always just jammed the tip of my Hakko 808 right up to the board. Pays to actually read the directions I guess! Never really have had any issues pulling traces up, but maybe I have just been lucky.

    #143 6 years ago
    Quoted from dasvis:

    Damn, I learn something here. I always just jammed the tip of my Hakko 808 right up to the board. Pays to actually read the directions I guess! Never really have had any issues pulling traces up, but maybe I have just been lucky.

    The worst case is when you're desoldering a pad (not a through-hole) that has no traces attached to it. Those are almost guaranteed to lift if you press the tip down on the pad. In fact your post prompted me to add that info above.

    #144 6 years ago

    Here's a video from BEST, Inc. that provides a little more detail on using a desoldering gun/station. In this case they're using a Metcal unit, but the technique is the same.

    #145 6 years ago
    Quoted from terryb:

    The through-hole should be completely free of solder when you're done. Turn the board over and make sure the pad on the component side is also completely free of solder. See image below where the right and left leads of the IC still have some solder. If this occurs, repeat the procedure above, but keep in mind you may need to add some solder first. As with the solder sucker, the desoldering gun requires a certain amount of mass to work efficiently.

    If this occurs frequently then you're not getting a good solder bridge (too little solder on joint), the gun temperature is too low or the joint is not being heated long enough before turning on the pump.

    Added the second paragraph to the desoldering gun post.

    #146 6 years ago

    Post-Inspection

    I covered this earlier, but it's definitely worth repeating at this point since I normally inspect the pads, through-holes and traces after desoldering. I begin with a visual inspection of both sides of the board using a magnifier. It's possible for partially damaged areas to still have continuity so don't skip this step.

    Next I'll check through-board and across board connectivity. With your meter set in diode/continuity place a lead on the bottom and top side of each through-hole and test for continuity. Do not insert the test lead into the through-hole since it's possible get false good readings even though the through-hole is damaged. After that check the traces on both sides of the board for continuity from each pad/through-hole to the next connection point.

    https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1/page/3#post-2741806

    #147 6 years ago

    High Heat Dissipation

    There are three factors that will determine how much heat is drawn away from a joint. The size of the component (large capacitors, bridge rectifiers, etc.), the size of the component's lead (flat bridge rectifier lead, for example) and the size of the trace (large ground plain, for example). Usually a couple of these issues combined will create a situation where a different technique is required.

    10-25 001.JPG

    When dealing with high heat dissipation components always use every technique available to you. The majority of time this will be sufficient to get the job done, especially if you only have one of the issues described above.

    1. Clean the joint and add flux.
    2. Use the proper size tip/nozzle.
    3. Use a high capacity tip.
    4. Add a little solder to the tip/nozzle to help form a solder bridge.

    In some cases you are going to need to increase your temperature (I suggest never above 800°). Although for large components with a normal sized trace I do not recommend going much above 700°.

    The easiest, and safest approach, is to cut the leads off and then desolder. Side-cutters will be able to get into places that diagonal cutters can't. For flat leads a Dremel tool with a cutoff wheel can be used. A component that costs a few dollars is a much wiser choice than damaging a board worth several hundred and I can tell you that in a production environment, the lead gets cut and life moves one.

    For large axial capacitors (one lead on each end) you can either cut the leads off or heat the joint with a soldering iron and remove one lead at a time. The same approach works for large radial capacitors (both leads on the same end) if there is enough distance between the board and the leads.

    Axial-Radial-Capacitors.gif

    One other technique if the capacitor is close to the board (and has round leads) is to heat the joint for one lead while gently tipping the capacitor towards the other side. Then do the same with the other lead. Do not try to completely remove the lead from the board in one try, just work it partially up. You may have to go back and forth a few times.

    For bridge rectifiers that have flat leads that are close to the board you can cut off each corner of the bridge with the Dremel and then cut the leads. Always clean any metal particles from the board by flushing with alcohol or air.

    If you have a large component with a large ground trace you may need to heat the joint on one side with the iron and use the gun on the opposite side. This will only work if you can get to both joints.

    I know some will groan when I mention solder wick, but I often find it works the best for high heat dissipation situations. This approach give you more flexibility since you don't have to clear the hole in one shot as with a solder sucker or desoldering gun.

    #148 6 years ago

    High Heat Dissipation Continued

    There are a couple of other techniques for desoldering difficult components. The first is to use a hot air gun/rework station to heat the front of the board while desoldering from the back. This works well with large ground planes. If the component leads are in close proximity you can use the hot air gun to melt all of the leads at once.

    It takes longer to get the solder to reflow than what you are used to with a desoldering gun so patience is definitely a virtue.

    The next option is ChipQuick, which is composed of 12% Tin, 18% Lead, 49% Bismuth and 21% Indium. The combination of alloys allows it to melt at a much lower temperature than 60/40 solder. It was designed for SMD removal but also works well for through-hole components.

    While not cheap (4.5 feet costs about $30), this is a great solution for flat lead bridge rectifiers with large traces. While not directly comparable, the manufacturer states that 2.5 ft of ChipQuik will remove 1,250 to 1,500 SMD pins.

    Another option is LOWMELT from Zephyrtronics, although the price per foot is about the same you can buy it in smaller quantities.

    Zephyrtronics LOWMELT Solder

    You add the ChipQuick to the joint and as it melts it blends with the 60/40 solder thereby reducing it's melting poiont. With this technique you can get all four joints of a bridge rectifier fluid at the same time. Once you're done always remove all of the solder from the area with your preferred desoldering method.

    The combination of ChipQuik and a hot air gun really makes removing bridge rectifiers a breeze.

    You want to use the leaded version of ChipQuik and do not need the kit they offer, just the solder since you can use whatever brand of flux you normally use.

    Both of these techniques are covered briefly toward the end of the desoldering video in the following post.

    Desoldering Video Post

    #149 6 years ago

    Practice, Practice, Practice

    Rather than risk damaging a board worth several hundred dollars I strongly suggest you spend some time practicing on something cheaper, and something that is not twenty years old. No matter which approach you take I suggest you solder/desolder the components multiple times since the risk of damaging a board increases each time it is worked on.

    You could pick up an old VCR, gaming system or computer that isn't working fairly cheap, or maybe free. Just make sure it uses through-hole technology.

    Several companies offer electronic kits where you can build a clock, robot, etc. You might find an item that you would be interested in building and learn to solder at the same time.

    Fry's Electronic Kits

    amazon.com link »

    Elenco sells a practice board at a good price ($11).

    Elenco Practice Kit

    Circuit Medic offers a nice practice board ($17) and a full kit with components ($49), which includes through-hole and SMD.

    Circuit Medic Practice Board

    Circuit Medic Practice Board with Components

    Practical Components has a kit that includes both through-hole and SMT components ($33).

    Practical Components Practice Kit

    For something more practical as it relates to pinball, have a look at the Pinduino kit for pinball lighting or a couple of Pinsiders make pinball test equipment that you can buy in kit form.

    Pinduino

    Pinitech Switch Matrix Tester

    Neoloch Pinball Test Equipment

    Board Rework Standards

    While it's not always feasible (or reasonable) for a hobbyist to adhere to industry standards in regards to board rework, it is still a good idea to understand best practices. Plus in many cases it's not any harder, or more expensive, to repair a board to the IPC standards.

    IPC (The Institute for Printed Circuits) is the generally accepted standard for printed circuit board rework. While their standards documents would cost several thousand dollars to purchase, there is an alternative.

    Circuit Medic has an online guidebook that covers all aspects of board repair and adheres to the IPC standards. While the guides are fairly simplistic, they will typically provide enough information to understand the best way to repair specific types of damage (damaged through-hole, lifted pad or trace, etc.).

    Circuit Medic Guides - HTML

    Here's a PDF version of their guide.

    Circuit Medic Guides - PDF

    Consumable Parts Resources

    The following companies sell circuit frames, copper foil and other products that help in the repair of damaged boards. Some of these products will be discussed as we get into advanced repair.

    Circuit Medic Products

    Best Inc. Products

    Pace Worldwide Products

    All-Spec industries carries the complete line of Circuit Medic tools and consumables.

    Circuit Medic Products at All-Spec

    #150 6 years ago

    Advanced Soldering

    It's called advanced soldering for a reason, it takes some experience to attempt these types of repairs. Only you can decide if your skills are at the level to attempt these techniques or if it would be wiser to send the board out for repair.

    Of course, if you've been following my guide you won't have to deal with damaged traces, pads and through-holes. Unless of course, the previous guy hacked the board.

    Before I go into the details, I should explain my three considerations when doing board rework (in descending order of priority).

    • Performance and Reliability. The repair should have the same performance as the original and be able to stand up to the rigors of a pinball machine. It's fairly easy to do board rework that will last a few months--maybe a year--but it's not quite so easy to do work that will last another twenty years.
    • Serviceability. If someone works on the game in the future they shouldn't have to wrestle with or redo any issues I've repaired. For example, if I'm attaching a jumper to the leg of an IC, I will first install a chip socket. This way the IC can be replaced in the future without worrying about the jumper.
    • Cosmetic. I try to make my repairs look as original as is reasonable (considering cost and time) and be as invisible as possible. Since "If it looks like shit, it most likely is shit," this will help other hobbyists in the future as they can feel comfortable in the repair and move on to other possibilities for the problem they are troubleshooting.

    As a general rule I spend 90% of my time repairing previous work and 10% actually troubleshooting and repairing the board. In fact a large percentage of the time, once I've redone the previous hacks, the board magically works.

    Pad and Trace Repair

    When it comes to pad and trace repair the two common solutions are copper foil or jumpers. Both methods are functionally equivalent and which one you select depends on the specific situation and how original you want the board to look.

    One other method I should mention, since I get asked about it a lot, is liquid trace or silver conductive epoxy. Other than a few specific situations, like repairing the glass on a DMD, I stay away from both. They add resistance to the circuit, which can cause problems in some situations, and the both will melt if hit with a soldering iron, which creates a serviceability issue.

    There are 392 posts in this topic. You are on page 3 of 8.

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