Few tips and tricks I’m using:
• Keep your soldering iron tip clean all the time (use wet sponge) and re-tin the tip periodically (nothing helps better than a clean tip)
• Use a reliable soldering iron (I’m using Metcal) that can maintain the tip temperature when touching the pads
• Use a pointy flat at the very end tip not necessarily the thinnest. This shape works for me better than pointy round tips when dealing with multiple pin devices
• Add extra flux (fresh brownish resin type) it makes the solder flow better and avoids bridges
• Use lower temperature solder (leaded one is much easier to wok with)
• Keep your soldering iron temperature few degrees higher than normal but not too high so it oxidates too quickly
• Find solder as thin as possible (I’m personally using 0.3mm which I’m not sure is readily available)
• Make sure your pads do not have extra solder on them before you install the device (use solder wick to remove the excess)
• When soldering two pins components add solder on one pad. While holding the soldering iron on the pad hold the component with the tweezers in a slight angle so the pin you working with lands first on the pad and slide it in place. Finish by soldering the other pad. When soldering multiple pins chips add solder on one pad, slide the component in position while holding your soldering iron on the pad. Make sure all the pins are aligned with the pads. Unsolder and repeat this step until you have perfect alignment. It makes next steps much easier. When done aligning solder one more pin on opposite corner of the chip.
• Apply solder only where needed not on the tip first and then to the board.
• To finish a multiple pin device work one whole side at the time not pin by pin
• Add flux (on the side of the device over the pins and pads) with a fine tip dispenser if your solder has too little or none
• Hold your soldering iron on the first pin of the line you working on (if the tip has the small flat I mentioned above hold the flat on the pin). The axis of the soldering iron should be held at about 45 - 60 degree in reference to the board. Pull few inches on solder and using the other hand to hold it try to place its end right at the point of contact between the tip and board. While gently pushing down the tip slowly start sliding it over the pins on that side. In the same time make sure you feed fresh solder at the contact point and the tip does not starve.
• I prefer to kind of over feed solder which usually sticks with the iron and does not create bridges and get rid of it by quickly shaking the iron
• If any bridges use flux and solder wick.
• For uniformity and professional look, especially if you had to fix bridges, run the soldering iron once more over the affected sides and add solder only if necessary
• Last but not least it is important to use nonmagnetic tweezers especially when dealing with smaller sizes components
• Use Head Cleaner to clean when finished soldering. Flux remover has the tendency to leave a whitish film and it is much harsher on certain plastics. For better results when cleaning the flux I use acid brushes. I cut their bristles short for more stiffness
Following these simple guidelines, even with my failing eyes, I can still replace (that includes removing a defective chip and installing a new one) 64 – 100 pin chips in about two minutes and toy with 0402 or 0201 components without any problems.
After all this is not rocket surgery .
HTH
Regards,
Nick
Originally Posted by mackrackit
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