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.
