(Topic ID: 140784)

TerryB's Soldering Guide

By terryb

6 years ago

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    #151 6 years ago

    Suggestion: When replacing bridges that share a heat sink such as BR1 and/or BR2 on a WPC driver board, remove the heat sink, then clip and unsolder the defective bridge. Install the new bridge's leads in the through- holes, **but don't solder it yet!** First, remount the heat sink to the soldered bridge, then the loose bridge, *then* solder the leads on the new bridge. Then reflow the solder on the leads of the un-replaced bridge in case the work tweaked the solder joint there.

    #152 6 years ago

    Pad and Trace Repair - Equipment and Supplies

    Copper foil, which is used for pad and trace repair, comes in several varieties.

    You can make your own pads and traces using one ounce copper foil tape. I should note though, this is not as easy as it sounds for narrow traces, and is just about impossible for pads. It does work well though for medium and larger sized traces.

    You can cut the tape lengthwise with an X-Acto knife and a straight-edge, although sometimes it will tend to bunch up. If you've got a steady hand and good eye, tweezers and a small pair of sharp scissors works well.

    Copper Foil


    Circuit frames are pre-cut traces/pads made from copper foil. They will either have a heat activated adhesive on the back (called dry film), a pressure sensitive adhesive (installed with a ball tip burnishing tool) or come with a two-part epoxy. While circuit frames are not cheap (around $40), you can do a lot of repairs with one sheet so your cost per application is reasonable.

    The two items in the lower part of the photo are Kapton dots and Kapton tape.



    Circuit Medic manufactures dry film circuit frames, Pace makes dry film and epoxy circuit frames and Best offers circuit board repair kits that include either type of circuit frame. You can purchase both the Circuit Medic and Pace products direct or at Stanley Supply & Services.

    Circuit Medic Circuit Frames

    Pace Circuit Frames

    Best Circuit Frames

    Stanley Supply Services

    Circuit frame pads with a diameter of .050/.060" are appropriate for IC's, small connectors, resistors and capacitors. For larger components use the .070/.080" size pad. For traces most circuit frames include a variety of sizes.

    Datak manufactures a Circuit-Fix kit (CF-1) that includes a spring clamp cutting guide for cutting traces from the included adhesive backed (3M) copper foil. The kit also includes a variety of pre-cut copper pads. The kit costs about $20 and you can get the copper foil sheet (CF-3) or the copper donuts (CF-2) for less than $4.

    Datak Circuit-Fix Kit


    The advantage of the Datak product is you can cut custom traces in any shape needed (for example, ground plane or curved trace). Be aware though, it's pretty difficult to make very narrow traces with this product.

    You will also want a pair of fine tipped tweezers for working with eyelets and circuit frames and a scraper for removing solder mask is not necessary, but does make things easier. I prefer curved tweezers.

    Curved Fine Point Tweezers

    Economy Curved Fine Point Tweezers

    Solder Mask Scraper

    You will be doing a lot of cleaning with alcohol when working with pads and traces--just touch some bare copper with your finger and you'll see the oils you've left behind. A push down alcohol dispenser will make your life a lot easier.


    #153 6 years ago

    Great thread! Thank you!!!! For taking the time! I've just learned so much more about soldering and repair all in one place, that is really going to help me!

    #154 6 years ago

    Kapton Tape

    One of the most tedious tasks in board repair is getting jumpers to stay where you want while soldering. Kapton tape, or dots, will make this task a lot easier. The following procedure will work with either.

    First stick your jumper on the adhesive side of the dot and then place the tip of an X-Acto blade under the dot.


    Use the X-Acto knife to position the trace on the board and then press down on the dot while removing the blade.


    Firmly press the dot in place and then bend or re-position the exposed portion of the jumper and solder it in place.


    Remove the dot, place a dot on the joint you just soldered, to hold it in place, and then solder the other end.

    #155 6 years ago

    Repairing Pads and Traces with Dry Film

    The first example is a 9 pin IDC connector with pads (no through-holes). Pin 9 on the right IDC connector has a broken trace on both sides of the pad and pin 5 has a broken trace on the right side (pin 9 is at the top and pin 1 at the bottom).


    I have selected a pad and trace combination. Since I'm doing pin 5 I could have used just the pad with a trace on one side, but since they're made with the trace on both sides I just used that setup. This technique also works if the pad is damaged.


    Be forewarned that while this technique will produce excellent results it is very delicate work and does take some experience.

    1. Using either an X-Acto knife or emery paper remove the solder mask from the traces you will be soldering onto (see first image above).
    2. Remove any oxidation on the trace and pad with emery paper.
    3. Clean the area with Isopropyl Alcohol and a lint-free cloth.
    4. Tin the board traces where you will be overlapping the new trace with the existing trace. Use solder wick to remove any excess solder.
    5. On the back of the circuit frame scratch off about 3/8" of the adhesive from the trace where it will overlap onto the existing trace and be soldered in place. You can leave the adhesive on the pad portion of the circuit trace unless you are placing the pad over a plated through-hole (although there are better solutions in this case).
    6. On the plated side cut the trace on each side of the pad and carefully lift it from the circuit frame.
    7. Tin the circuit frame where you removed the adhesive. Use solder wick to remove any excess solder.
    8. Place the pad/trace on the Kapton tape (copper side against the adhesive) and after positioning, press down on the tape (see first image below).
    9. Set your soldering iron to 475° and heat the pad/trace through the Kapton tape, while pressing down, for 30 seconds. Note: Some manufacturers recommend different procedures, so follow the directions with the product you are using.
    10. Let the adhesive cure for 24 hours. Note: In a production environment we skip this step, but I would not in a home environment.
    11. Solder the overlapping portions of the new and existing traces (see second image below). Use an orangewood stick to press down on the new trace to ensure good contact with the existing trace.
    12. Remove the Kapton tape.
    13. Apply solder mask, paint or green conformal coating (this will be covered in detail later) over any exposed copper (other than the pad of course).

    Note: You could also remove the pad--and definitely want to if it is damaged--and use the same technique as described above. Either approach is fine, some just prefer one over the other.



    Circuit Medic sells a bonding press with heated bonding tips of various shapes for sealing the circuit frame on the board. I have never had a problem using a soldering iron instead, and most other manufacturers recommend the soldering iron method.

    The same general technique is used for a trace circuit frame.

    While you can buy copper foil with conductive adhesive I always recommend removing the adhesive and soldering the connection. You won't be adding any resistance to the circuit and will have a stronger connection.

    #156 6 years ago

    Wow, wow, wow. Thank you Terry!

    #157 6 years ago

    Trace Repair, Dry Film

    Here's a video from Best, Inc. on replacing a damaged trace with dry film. The same technique applies if you are using copper foil tape, although the adhesion method will be different.

    #158 6 years ago
    Quoted from terryb:

    Pad and Trace Repair - Equipment and Supplies
    Copper foil, which is used for pad and trace repair, comes in several varieties. You can make your own pads and traces using one ounce copper foil. I should note though, this is not as easy as it sounds for small traces, and is almost impossible for pads. It does work well though for medium and larger sized traces.

    When cutting traces and pads from copper tape, I've gotten good results using tweezers and a tiny pair of sharp scissors. Copper tape tends to bunch up when trying to slide an exacto blade down its length. This is probably impossible to do without steady hands.

    amazon.com link »

    #159 6 years ago
    Quoted from ForceFlow:

    When cutting traces and pads from copper tape, I've gotten good results using tweezers and a tiny pair of sharp scissors. Copper tape tends to bunch up when trying to slide an exacto blade down its length. This is probably impossible to do without steady hands.

    Very good point. I added that info to the post.

    #160 6 years ago

    Jumper Wires

    For low current circuits I use 30 gauge wrap wire. For ground, supply voltages and higher current circuits I use 22 gauge solid wire with a PTFE (Teflon) coating. The PTFE coating allows you to trim the leads much shorter since it won't shrink or melt as easily as standard shielding when soldering in close proximity. Resistor leads also work for for short jumpers.


    The equivalent solid wire size for various trace widths are as follows:

    • .025" trace and less -- 30 gauge
    • .082" -- 26 gauge
    • .125" -- 23 gauge

    According to IPC standards the maximum run for bare wire is half an inch. Anything longer and you should use insulated wire.

    Best practices are to route the jumper along the same path, and side of the board, as the original trace.

    If you are running a long jumper it should be attached to the board in one or more spots. Wire dots, hot glue or clear RTV silicone all work fine.

    Although optional on short jumpers, I use high temperature epoxy to maintain the integrity of a jumper if there is potential reflow during future soldering operations. This is especially important if you jumper is close to a pad or through-hole.

    #161 6 years ago

    Connector Repair, Jumper

    Next we'll repair the same connector using jumper wires (remember no through-holes in this case, just pads). While the traces to pin 9 where broken on both sides and only one side on pin 5, I used the same approach for both.

    First take some 30 gauge wrap wire, remove the insulation, and make a loop in the middle that will fit around the pin on the connector.


    Remove the solder mask from the trace on each side of the connector where you will be soldering and tin it. Place the wires on the pins on the connector and install the connector. Bend the wires as needed to line up with the trace and ensure they lie flat on the trace, then trim the ends. A solder pick with a slot in the end works well for bending jumper wires.


    Solder the connector in place making sure that solder flows through the hole and onto the wire loop and pin. Solder the wire on each side to the trace. Press down while soldering with an orangewood stick to ensure good contact.


    Always check your trace connections by pushing laterally on the wire with an orangewood stick. Clean up the flux and seal the wire and trace.

    If the trace was only broken on one side of the pad you could instead bend the jumper into an L shape, run it through the hole for the pin and onto the trace (this is called a stitch, and we'll cover it shortly).

    #162 6 years ago

    I forgot to mention ChipQuik and hot air guns in the post on removing difficult components. Luckily I was able to steal the next post and add the information. You'll definitely find ChipQuik interesting if you're not familiar with it.


    #163 6 years ago

    Repairing Damaged Pads

    In some cases you will come across pads that do not have a trace connected to them. As a side-note these are exceptionally easy to lift when desoldering (even with the Hakko). The reason these pads exist, and why you should repair them, is they help solder flow through the hole to the joint on the opposite side. Since these are pads, not through-holes, there is no conductive material inside of the hole in the board.

    In the image below you can see the pads on the backside of the connectors I repaired previously, a sheet of copper donuts and a single pad removed from the sheet. Unfortunately I do not have a board with a damaged pad so we'll have to do this virtually.


    The first, and easiest option, is to catch the fact you have lifted a pad and attempt to recover it. If the pad is not damaged you can use high temperature epoxy to reattach it to the board. This also works to reattach a partially lifted pad.

    If you're not that lucky you can use either dry film pads or 3M pre-cut pads like the Datak product discussed earlier. Although the 3M solution is quite a bit less expensive I've had problems with some sheets where the cut does not go all the way through the foil. This makes it especially difficult to remove the inner circle of the donut.

    Whichever route you go, if the pad is damaged remove it before installing a new pad.

    I have not tried this, but a friend of mine swears by the following tool for removing the 1/8" pads from the sheet (the larger pads are easier to remove with an X-Acto so no tool is required). He uses a 1/8" circle hand punch to remove the pad from the foil and seperate the inner hole at the same time (note the center punch in the tool below).

    Unfortunately the one he uses is an industrial brand that is probably 20 years old and has no markings. It is similar to the model below from Fiskar's, but check out whatever brand you choose before purchasing.


    If the hole in the pad is smaller than the hole in the board just slightly ream out the pad with a small drill bit.

    #164 6 years ago

    Repairing Damaged Pads Continued

    Use the following procedure for dry film.

    1. Clean the area with Isopropyl Alcohol and a lint-free cloth.
    2. Select the proper size pad and remove it from the circuit frame. If the circuit frame has traces connected to the pad cut them before removing the pad.
    3. Place the pad/trace on the Kapton tape (copper side against the adhesive) and after positioning, press down on the tape.
    4. Set your soldering iron to 475° and heat the pad through the Kapton tape, while pressing down, for 30 seconds. Note: Some manufacturers recommend different procedures, so follow the directions with the product you are using.
    5. Let the adhesive cure for 24 hours. Note: In a production environment we skip this step, but I would not in a home environment.
    6. Remove the Kapton tape.
    7. Clean the pad with Isopropyl Alcohol and a lint-gree cloth.

    Use the following procedure with the 3M pads. In the case of a damaged pad that is oval rather than round you can go with a slightly larger pad and trim each side to make an oval.

    1. Clean the area with Isopropyl Alcohol and a lint-free cloth.
    2. Select the proper size pad and remove it from the copper foil. Ream the hole as necessary.
    3. Place the pad/trace on the Kapton tape (copper side against the adhesive) and after positioning, press down on the tape.
    4. With your burnishing tool thoroughly press the pad down onto the board. The adhesive is activated by pressure so spend a couple of minutes to ensure you get good adhesion.
    5. Let the adhesive cure for 24 hours. Note: In a production environment we skip this step, but I would not in a home environment.
    6. Remove the Kapton tape.
    7. Clean the pad with Isopropyl Alcohol and a lint-free cloth.
    #165 6 years ago

    Repairing Damaged Through-Holes - Stitch Method

    The same technique is used for repairing vias and through-holes. The only difference is the through-hole will have a component installed whereas the via won't. In the case of IC's always use a socket after installing the stitch in a through-hole.

    The first step when dealing with through-holes is to make sure they are intact, not just on the surface of the board, but also through the board. Check for continuity and then inspect visually for damage (with a magnifier). It is possible to have continuity and still have the through-hole damaged.


    Through-holes can be repaired using either the stitch method or by installing eyelets.

    In our first example we have two damaged vias and the trace going to each is also damaged. On the bottom side the via is also damaged, but the trace intact. We'll be using the stitch method to repair both the via and the trace at the same time.


    1. Remove any remaining portion of the via on both sides and use a small drill bit to clean the hole.
    2. Remove the solder mask from the portion of the trace the jumper will be attached to on both sides of the board. Clean the trace with Isopropyl Alcohol and a lint free cloth.
    3. Bend the wire into an L shape and insert the long end into the via. Hold the wire in place with tape and solder it to the trace, using an orangewood stick to ensure good contact.
    4. Turn the board over and bend the wire to align with the bottom trace. Hold the wire in place with tape and solder it to the trace, using an orangewood stick to ensure good contact.
    5. Fill the via with solder.
    6. Remove the Kapton tape.
    7. Seal any bare copper wire.


    If you're having trouble with the jumper moving around while soldering you can stick a toothpick in the via/through-hole to hold it in place.

    #166 6 years ago

    Eyelet with Jumper

    In the image below you can see where I've installed eyelets on every through-hole on the left side of the IC. In addition the traces were damaged on several of the pins. In most cases the eyelet overlapped the damaged traces (we'll cover this later), but on pins 10, 11 and 13 (pin 1 is at the bottom-right) I will need to add jumpers.


    On pin 11 the trace was broken in two places so I ran a longer jumper wire and attached it to the left side of the resistor. Many people feel more comfortable with this method rather than tacking onto a board trace. If you're in that category, that's fine, it's a perfectly acceptable solution.

    This is also a good example of a situation where you could use dry film or copper foil to replace the damaged trace. Prior to installing the eyelet, install the trace, tin the part of the trace which will be under the eyelet and then install the eyelet and solder it where it overlaps the trace.

    In the image below you can see the area with the socket and IC installed. Once it's cleaned up and a protective coating is applied the repair will be almost invisible.


    #167 6 years ago

    First of all, thank you so much for this thread! I appreciate all of the time you are putting into sharing techniques, tips, etc.

    I'm about the biggest beginner when it comes to anything electrical that you'll find. I'm trying to learn as much as I can, both to challenge myself and to understand my limits before I do any damage to a machine. Do you have any suggestions for exercises to practice soldering before I attempt actual repairs? I am pretty sure I have a lot of cold solders and ugly connections in me!

    PS: If one of your photos has a NSFW tag, I fat-fingered it while reading on a phone! I hope I removed it but I can't tell if the tag stuck. There was nothing offensive in your soldering pictures...now if *I* were to post any right now, I'm sure a lot of people would be horrified, lol!

    #168 6 years ago
    Quoted from DaWezl:

    Do you have any suggestions for exercises to practice soldering before I attempt actual repairs?

    Good question, especially since I forgot the practice, practice, practice lecture. You could pick up an old VCR or computer that isn't working fairly cheap, or maybe free. Several companies offer electronic kits where you can build a clock, or robot, or something. You might find an item that you would be interested in building and learn to solder at the same time.


    amazon.com link »

    Circuit medic offers a nice practice board ($17) and a practice board with components.



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




    Hopefully we can get some more suggestions and I'll add a post on this topic.

    #169 6 years ago

    Repairing Damaged Through-Holes - Eyelets

    My preferred method of repairing plated through-holes is using eyelets.


    Plated through-holes are actually one physical part and the board trace a second physical part. They are electrically connected once the board is wave-soldered. It is fairly common for the connection to break right at the point where the through-hole is soldered to the board trace, especially if the through-hole is damaged. One advantage of the eyelet method is that it is slightly larger than the original and you can often overlap the trace and thereby eliminate the requirement for a jumper or copper foil repair.


    There are three types of eyelets: rolled flange, flat flange and funnel flange. The rolled flange eyelets give you the best physical contact of the three if the pad is still intact. The flat flange eyelets do not spread as much so they can be spaced closer together. Funnel flange eyelets allow solder to flow easily around the barrel and the solder joint is visible so they can be quickly, and easily, inspected. In most cases either rolled or flat eyelets are used.


    My preference is brass or copper eyelets with a tin coating since the solder flows better. Here's a FAQ that provides additional information on eyelets.

    Eyelet FAQ

    Unfortunately most manufacturers have a minimum order quantity (25-100), are expensive ($2-$3 each) or have a limited selection. I've recently switched over to flat flange eyelets on chips since they spread less, although for most people the Keystone rolled flange eyelet is probably a more economical choice.

    You can purchase the Keystone line of rolled flange eyelets (brass with a tin coating) at Mouser Electronics (10-14 cents each). The most common eyelets you'll need are 1/16" diameter for most IC's, 3/32" for transistors and 1/8" for large connectors. The best lengths to get are .093" or .125". I think the .093" is perfect for WPC era boards, but some prefer the .125" and then file it down a little bit, and trim the diameter, when needed.

    Keystone Eyelets at Mouser

    The BEST flat flange eyelets are copper with a tin coating and cost $24 for 100. I use the .068" OD and .102" length specifically for chips. I'm not sure why their OD's don't align with common drill bits sizes (1/16" or .0625"), but you can just ream the whole slightly. The length is slightly more than the Keystone so you may want to file them a little.

    BEST .068" by .102"

    Eyelet selection criteria:

    1. The eyelet inside diameter should be a .075 - .500 mm (.003"-.020") greater than the component lead diameter.
    2. The length of the eyelet barrel should be .630 - .890 mm (.025" - .035") greater than the thickness of the circuit board.
    3. The eyelet flange diameter should be small enough to prevent interference with adjacent lands or circuits. Although it is not uncommon to trim the sides of the eyelet into an oval shape which provides more clearance.
    4. The clearance hole drilled through the circuit board should allow the eyelet to be inserted without force but should not exceed .125 mm (.005") greater than the eyelet outside diameter.
    #170 6 years ago

    Eyelet Tools

    Installing the eyelets requires a staking tool, which clinches down the eyelet, an anvil, which supports the bottom side of the eyelet, and in a production environment you would use an eyelet press (staking tool on the top-right and anvil on the bottom-right in the image below). The eyelet is placed in the damaged through-hole and then crimped similar to the way a hollow rivet is installed in a ramp flap.


    While the eyelets only cost about ten cents, the eyelet press runs about $1,300 and the staking tool and spring-loaded anvil will cost between $100-$300 each. Plus you need a staking tool and anvil for each size eyelet. Thankfully, there are a couple of cheaper options.

    Link to Circuit Medic eyelet press and for our European friends a link to one manufactured by a Germain company, Bungard (much better price by the way).

    Circuit Medic Eyelet Press

    Bungard Eyelet Press


    Best Electronics sells a plated through-hole repair kit, which costs about $200. The kit includes several sizes of setting tools and a basic anvil (non-spring-loaded), which are used with a hammer to clinch the eyelet.

    Best Plated Through-Hole Repair Kit

    Although you can put together your own kit for a lot less with the following products.

    Mouser carries the Keystone setting tools. The Keystone 1714 staking tool is used with 1/16" to 3/32" diameter eyelets and the 1715 is used with 1/8" eyelets. Each costs about ten dollars.

    Keystone 1714 Staking Tool

    Keystone 1715 Staking Tool

    You can buy a setting tool (staking tool on one side and anvil on the other) and tool base, which holds the anvil, at Circuit Medic. The setting tool (115-3120) costs $17 and the tool base (115-3122) costs $10.

    This is not as good a setting tool as the Keystone since it does not roll-over the edge of the eyelet, so just use the anvil side of the tool. You would need two setting tools anyways since the staking tool and the anvil are used at the same time.

    Circuit Medic Setting Tool

    Circuit Medic Tool Base

    Although I don't think the spring-loaded anvil is necessary, you can buy them at the Engineering Lab for $149. You could also use a cupped tip punch as the anvil, but the setting tool from Circuit Medic works better.

    Engineering Lab Spring-Loaded Anvil

    So for a grand total of $47 (plus some drill bits and a small hammer) you can do a professional eyelet repair.

    Of course if you wanted to get fancy you could modify a bench press to hold the staking tool and anvil.

    #171 6 years ago

    Thanks to zaza for another great graphic and german-pinball for a link to an eyelet press manufactured by a German company, Bungard (added to the post above).


    #172 6 years ago

    Eyelet - Example 1

    In our first example we'll repair the circled through-hole in the image below. In addition to the damage to the through-hole, the trace going to the right has been lifted and the trace going to the left is mangled (it is intact though, but looks narrower than it is since it was folded over).


    First select an appropriate eyelet and then use a drill bit of the same size to clean out any remaining barrel on the damaged through-hole. Do this by hand rather than with a power drill. You will be slightly enlarging the hole to make sure all of the barrel is removed.

    The two images below are of the front and back of the board after cleaning the hole with a 1/16" drill bit. Normally the through-hole pads come off while using the drill, but if they are intact--and adhered to the board--you can leave them if you so desire. If you do be sure and clean and tin the pad before installing the eyelet.

    If you leave the pad on the board you will need to flow solder all the way around the eyelet prior to installing the component.



    Be careful not to lift or damage any existing traces during the process. When cleaning out the hole work from the side where the traces are in order to minimize the chances of damage.

    Before installing the eyelet remove the solder mask from any traces you will be overlapping and clean and tin the trace (remove any excess using solder wick--you want a very thin layer of solder). In the image below you can see the eyelet in place.

    Note: I was focused on taking pictures, instead of thinking, and put the eyelet in backwards. Always place the flange end of the eyelet on the non-component side of the board.


    Make sure the flange on the eyelet doesn't interfere with other traces, through-holes or pads. Be aware it will expand when you set it, although it can be trimmed after installation.

    #173 6 years ago

    Eyelet - Continued

    If you're doing two or more through-holes right next to each other the flanges will most likely end up touching. In this case, I file two flat sides on the flange, turning the circle into an oval, before installing the eyelet.

    Easiest method is to insert the non-flange end of the eyelet in a straight, round solder pick (or an awl) and then hold the flange in place with your fingernail while running it across a file.

    I re-installed the left trace using high-temperature epoxy, and it is now pressed under the eyelet. The right trace was still short of reaching the eyelet so a jumper will be necessary (as described earlier).

    All I had on hand at the moment was a .125" eyelet and as you can see below it's a little long (again, eyelet is installed from wrong side of board). You want about 1/32"-1/16" extending beyond the board. I used a file to remove about half of the extra length. If the flange is too long you risk interfering with other traces when you roll it over.


    Always use a very small hammer when clinching the eyelet to prevent damaging the board. It does not take much pressure and you are less likely to split the eyelet if you use multiple light taps.

    Place the side of the eyelet with the flange on the anvil. Before using the staking tool you can use a center punch to start rolling the edge of the eyelet (this helps prevent splitting the eyelet as we proceed--although this is not a cause for rejection). Take the punch and place it in the non-flanged side of the eyelet. While holding it at about a 45° angle from the board roll it around the edge of the eyelet until you have a slight flare.

    Now while holding the board on the anvil, put the staking tool in place and give it a few light taps. You're done when the top and bottom pads are tight against the board and the eyelet won't rotate. It is important to make sure the eyelet is clinched properly. If you're using flat flange eyelets you may want to finish up with a flat punch.

    I find I get a better looking job if after the about six taps I flip the board over and give it another 6 taps from the opposite side. You'll have to experiment a little bit and figure out what works best for you.

    #174 6 years ago

    Eyelet - Continued

    Inspect for any areas where either side of the eyelet may have spread and is touching another eyelet, pad or trace. If necessary you can trim the eyelet with an X-acto knife or Dremel tool with a cut-off blade. Just be careful not to damage any other traces (this is why I usually trim the flange in advance when working in tight spaces).

    Below you can see the finished product (sorry about the blurry picture). My anvil slipped to one side while setting the eyelet and I ended up with a small ridge on the eyelet. I just trimmed it off with an X-Acto, but you could also use a small file.


    At this point you need to solder any overlapped traces to the eyelet. If you left the pad intact you will need to flow solder around the entire eyelet. In my case just the left trace needed solder, since I will be adding a jumper to the right trace before installing the socket.

    Make sure not to get any solder in the eyelet hole. If you get too much solder on the joint just use some solder wick to remove the excess. I always install a socket on any IC's to prevent problems with solder reflow in the future.

    #175 6 years ago

    I added tweezers and a scraper to the pad and trace equipment and supplies post.


    #176 6 years ago

    Eyelet - Example 2

    In the image below the eyelets have already been set for pins 10, 16, 17 and 18 and the holes drilled for pins 11-15 (pin one is at the bottom right and then count counter-clockwise). Several jumpers will also be required since the breaks in the trace are too far away for the eyelet to cover them.


    You can see one jumper already partially in place for pin 10. It will be inserted into the through-hole before installing the socket. I will also be installing jumpers on pins 11 and 13.

    In the image below the rest of the eyelets and jumpers are installed on the left side of the chip.


    Below is the bottom of the board with the eyelets installed on one side. Note that a couple of the eyelets that I did not file before installation are touching and will have to be cleaned up with an X-Acto or Dremel with a cut-off wheel. While this problem is more prevalent on the flange side of the eyelet, it can also happen on the component side.

    At this point any joints where the eyelets are overlapping the trace (both sides of the board) are soldered prior to installing the chip socket.


    If you are having trouble with the eyelets touching on the component side either trim them after installation or slightly file the length prior to installation.

    In the image below the rest of the through-holes have been replaced, and the socket and IC installed. Once cleaned up and a green protective coating applied over the bare traces, the repair will hardly be noticeable.


    #177 6 years ago

    In case you were wondering why anyone would spend the money on an eyelet press, just watch this video. While the method I presented works functionally and is reasonably good looking, an eyelet press does much better, and is a hell of a lot faster.

    Thanks to german-pinball for the link.

    #179 6 years ago

    Eyelet Repair Video

    I don't have a really good video of a rolled flange eyelet installation, but the following will give you a general idea of the process. In the video they are using a flat flange eyelet instead so the technique is slightly different (I will update my post on eyelets and explain the differences and provide more info on flat eyelets).

    #180 6 years ago

    Solder Mask

    Once you're done with the repair any exposed copper traces should be treated with solder resist (also called solder mask) to prevent oxidation of the traces.

    The most common approach is to use a green conformal pen (this is not what was used originally, but will serve the same purpose). While the pen's are fine for doing small traces, they are rather tedious on larger areas. I am also not thrilled with the color match or flow of the paint.

    Of course we could use green solder mask, but it is difficult to work with and almost impossible to match the original finish without some experience. From a repair perspective we don't really care about the chemical properties of the solder mask--which are important during board manufacture--only that it protects the traces from oxidation and has an original look.

    One choice is Testors 1601 Transparent Candy Emerald Green. It is available in a 3 oz. spray can and will match boards with a lighter green mask. You can either mask off the board and spray paint, or for smaller areas just spray a little into a small cup and brush on.

    Another option is Pebeo Vitrio 160 a transparent paint used on glass. It can be airbrushed or applied with a brush, although it does require heat curing. The Mint 37 is a touch darker than the Testors, and if you need darker yet try the Tea Green 15.

    When using paint do not cover leads or pads since it makes them impossible to solder without removal of the paint. When dealing with the ground plane you want to leave a bare area where any mounting screws are installed. This provides a path to ground, and I usually just add a little solder to the area to protect the copper trace.

    #181 6 years ago

    At this point I've covered everything I had planned to cover. I'll be going through and cleaning up the post and possibly adding some more videos or images (cough.. zaza.. cough..). If you have any questions, would like anything clarified or just want to discuss stuff please post.

    Also, if there is something you would like covered that I have not touched on, please let me know.

    #182 6 years ago

    Very valuable topic Terry, thank you so much.
    If you need more images photoshopped or drawn, just ask.

    #183 6 years ago

    I enjoyed reading so far, thanks alot!

    #184 6 years ago

    Thanks, Terry. This I suspect will be a useful reference for years to come.

    #185 6 years ago

    How about SMD tips for things like optos?

    Also, I'm having trouble finding anywhere that has that slotted pick. Any tips for that one?

    #186 6 years ago
    Quoted from aobrien5:

    How about SMD tips for things like optos?

    Are you interested in doing the work with standard soldering/desoldering tools or with a hot air gun?

    Quoted from aobrien5:

    Also, I'm having trouble finding anywhere that has that slotted pick. Any tips for that one?

    Radio Shack sells a set of 5, which includes the slotted pick.

    Here's a set from Fry's:


    It's rare to find them sold individually and if they are they cost about the same as the set.

    #187 6 years ago

    One comment about solder mask...

    I like to use clear conformal coating in an aerosol can.

    It doesn't look original, but it's pretty easy to look at a repaired area, and be sure the corrosion hasn't returned.

    While it *shouldn't* return if it's properly sealed (oxygen is required for corrosion), if it does, you may not notice it until it's spread pretty far.

    #188 6 years ago
    Quoted from terryb:

    Are you interested in doing the work with standard soldering/desoldering tools or with a hot air gun?

    uhhh, yes? hah. When I had to do it, it took 4 hands and got hot on the fingers because I was using standard soldering tools. When looking for an example picture, I found pinballlife and marcos now sells opto emitter/receivers on boards that have through holes, so maybe I'm just doing it wrong.

    Quoted from terryb:

    Radio Shack sells a set of 5, which includes the slotted pick.

    Here's a set from Fry's:

    Thanks, that helped me find the set you pictured on Amazon.
    amazon.com link »
    amazon.com link »

    #189 6 years ago

    I've updated the eyelet post to include information on both rolled flange eyelets and flat flange eyelets. The latter spreads less and works well on chips.


    #190 6 years ago

    Surface Mounted Devices

    Since aobrien5 asked about SMD repair, and we are starting to see some SMD components in pinball games, I thought I would briefly touch on the subject.

    This is not intended to be a thorough SMD soldering guide (that would take several pages again) and most people aren't going to spend the money for a hot air rework station anyways. Instead I will give you a few tips to help solder/desolder dual-lead components (resistors, capacitors, leds, optos), and will cover techniques using standard soldering equipment and a hot air gun.

    I am not recommending any of these options for chip soldering/desoldering unless specifically stated as such.

    One other thing I should note is that some of the advice will appear contrary to what has been presented earlier. The apparent contradiction is because the physical differences between through-hole and surface mount technology require very different techniques.

    First though, how about a little hot air rework porn.

    #191 6 years ago

    Dual-Lead SMD Desoldering

    There are several techniques available for desoldering dual-lead SMD components. The simplest technique is to flood the pads with solder, which will provide a larger mass for maintaining heat and keeping the solder in a liquid state.

    Liberally apply solder to the first joint and then move to the second joint and repeat. Then, if needed, go back and forth between the two joints with your iron until you can push the component off of the pads.

    If you are having trouble with this technique you could instead use ChipQuik which lowers the melting point of the solder and makes this technique extremely easy. The ChipQuik approach can also be used on SMD chips. 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

    If you have a hot air gun you can add flux to the joint and then move back and forth between the two pads. Use an orangewood stick to push the component off the pads once the solder flows. You don't really need to add solder with this technique, but it does make it a little easier as you are learning.

    The main problem I see when people are using a hot air gun or rework station is they expect it to work as fast as their soldering iron or desoldering gun, and when it doesn't they crank up the heat. A simple component will take 30 seconds to one minute to remove with a hot air gun, so just be patient.

    Although most people aren't going to spend the money, a very cool tool is a hot tweezer. Of course you could always use two irons to melt the solder, but that's kind of rookie.

    #192 6 years ago

    That's amazing, especially the hot air station. Will you be getting to how to solder wires onto smd components like this?


    #193 6 years ago

    Dual-Lead SMD Soldering

    The most important thing to understand about soldering SMD components is they are self-aligning. As the solder melts the component leads will align themselves with the pads. This is the reason why SMD components are soldered using a no-touch approach since applying a soldering iron to the joint defeats the self-alignment effect. I should also mention the same issue arises when using Kapton tape or physically holding the component in place.

    So while you can solder simple SMD components with a soldering iron, a hot air gun or rework station will always perform better and provide better joints. This, and the fact that SMD joints are harder to inspect, is why I do not recommend installing SMD chips with a soldering iron.

    The key to using a soldering iron on dual-lead components is flux. Unlike through-hole components you want to add the solder to the iron and then carry it to the joint. Since the flux in the solder is burned off by the iron's tip additional flux should need to be applied to the joint.

    This technique takes steady hands and a good eye (magnification helps a lot). Since we are hindering the auto-alignment effect you want to be careful not to move the component with the iron tip.

    1. Add flux to both of the pads and then add solder to one pad (you want to add a little more solder than if you were just tinning the pad). In addition to its other benefits, the flux helps hold the component in position.
    2. Carefully position the component and reflow the solder on the tinned pad while holding the component with a pair of tweezers.
    3. Add more flux to the other joint.
    4. Melt a small amount of solder on the iron tip and carry it to the joint. If necessary you can hold the component down with an orangewood stick, or tweezers, to keep it from sliding off the pad.
    5. Once the solder flows remove the tip from the joint.
    6. Inspect the solder fillet and the pad/component alignment.

    Acceptable solder fillet for no-lead component.


    The first three minutes of the following video from CuriousInventor show this technique.

    After the three minute mark they cover using the same technique to solder an IC. I strongly advise against installing chips with this technique. Even someone with years of experience will find it frustrating and likely to result in poor solder joints. This really is a case of the right tool for the right job.

    #194 6 years ago
    Quoted from aobrien5:

    Will you be getting to how to solder wires onto smd components like this?

    The fastest way, if you've got a steady hand, is as follows. Apply flux to wire and pad. Tin wire and pad. Apply flux again to wire and pad. Place wire on joint and heat until the solder flows. If you're having trouble holding the wire steady use an orangewood stick to hold it in place.

    Another technique would be to use polyimide tape, an orangewood stick or crossover tweezers (clamp the wire to the board) to hold the wire in place. Flux the joints and then apply solder to your iron tip and carry it over to the joint. Hold the tip on the joint until the solder flows.

    #195 6 years ago

    Hot Air Gun

    For those of you who would like to start learning how to do hot air rework this post will provide a starting point. Of course there is much more to learn, but that is beyond the scope of this article. This technique can also be used to solder surface mount chips.

    A hot air gun is much cheaper than a hot air rework station and the only downside is the cost and storage requirements of solder paste.

    Solder paste is a combination of solder and a thick flux. It is available in leaded and non-leaded versions and has a limited shelf-life and in some cases needs to be refrigerated. The MG Chemicals product is leaded euctectic solder, must be refrigerated and has a 12 month shelf-life. The Zephyrtronics product is also a leaded euctectic solder and has a six month shelf-life without refrigeration.

    The ZephPaste is more expensive at $25 for 12 grams ($16 for 35 grams for the MG product) but has the storage advantage (no idea why, but most wives don't like non-food items in the refrigerator).

    MG Chemicals 63/37 No-Clean Solder Paste

    ZephPaste 63/37 No-Clean Solder Paste

    You apply a small dot of solder paste, or a thin bead in the case of an IC, to the pads and position the component using tweezers or a dental pick. The solder paste will hold the component in place. In a production environment you would use a pre-heater as shown in the Zephyrtronics video and the appropriate size and shape of nozzle.


    For our example of a dual-lead component you'll just be using the small round nozzle that comes with your hot air gun. Move the hot air gun between the two pads until the solder paste flows. If the component is moving on the pads (other than the self-alignment) then your air flow setting is too high. Again, patience is the key. Other than that it's a pretty easy process.

    In the video they are applying the solder paste using a screen (similar to silk-screening a warning label on a backbox), which would be typical in a production environment, but not necessary for rework. Also take note of how the transistor self-aligns itself as the solder flows.

    #196 6 years ago

    Hot Air Rework Station

    I'm not going to delve into this issue deeply, but I do want to explain the important difference between a hot air gun and a hot air rework station. With a decent rework station you have the ability to create temperature profiles, and this is the key reason why they should be used when soldering/desoldering SMD chips.

    The profile controls a user defined stepped temperature increase. The component under repair, adjacent components and the board are protected from damage by using multiple stages to pre-heat, melt the flux, reflow the solder and cool down the component. Advanced systems utilize a temperature probe placed in the solder ball to monitor and control the heating/cooling process.

    Profiles can be used solely with a rework station or in conjunction with a pre-heater.

    Here's an example of what a 3 stage soldering/desoldering profile looks like.


    I should also note that hot air should not be used to solder/desolder DIPs. They are not manufactured to withstand the temperatures (the package can crack) and for those where hot air rework is deemed acceptable they will typically have very specific pre-heat and cool-down conditions.

    #197 6 years ago

    Just came across the Hakko FR-300 for $249. It looks like they're giving the discounted edu price to anyone.

    I do not know how this compares to the Pinside group buy.


    #198 6 years ago

    FX600 for $48 (44% off) at Tequipment. I would think that' a hell of a price.


    Also have the FR-300 for $249.


    In case you think I'm just bored this morning, I'm looking for a new hot air rework station and keep coming across other stuff.

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