By Xin Feng [09/07/02]
This tip was written originally for overclocking Libretto 70. I once got a message from an L70 overclocker, he solder the pin57 too long so the pad dropped off from the motherboard. I have been soldering since 7 and I was very lucky to have a very good teacher. He was a senior electrician, Mr. Jiang, who worked for a huge factory of 10K employees in China. Mr. Jiang's eldest son was my classmate and he really wanted this son to inherit his super electrical skills. Unfortunately, the son had no this kind of interest. Fortunately, he saw his hope on a stand-by student, me. He told me to solder correctly from my first start and grown me with good soldering habits. I benefit from his training very much. I once had a chance to train 30 country girls for soldering and, after a single day, they were all able to solder at world-class qualities. So, I am sure you'll benefit a lot after reading my following tips:
1) For this kind of micro-soldering, use a 15W soldering iron with the sharpest, grounded tip only. Fortunately such a soldering iron does not cost you a fortune. I am using one from Radio Shack for only $7.99 (item# 64-2051). For more general soldering works, I recommend the Radio Shack dual-wattage iron for $9.99 (#64-2055), which has a very convenient and useful 15-30 watt switch. You should always coat a new tip with solder. While it is heating-up for the first time, apply rosin core solder to the tip until the top 1/4" is fully coated. Always throw away extra solder from the tip and keep the tip with a clean, thin coat of solder. Yes, I meant throwing out, not wrapping out, the latter should be for tip clean only. You don't need to clean the tip often, but you should throw out the extra solder from the tip all the time or your soldering work will be a mess.
2) Never let the tip to be too hot. The best method to check tip's temperature, is to apply a little rosin core solder to the tip. If the smoke fade in less than 3 seconds, the tip is too hot. You can never get a good soldering with a too hot tip, believe me, and you are highly in the risk of burning out everything it touches.
The simplest and best method to keep a tip from overheating is to serial a 1N4004 diode. As a commercial example, the Radio Shack $20 (currently on sale for $15) soldering station has nothing but a diode for the 20W/40W switching. Its iron is not good though - way too long (the reason for on sale), but I still like its convenient one switch for on/off/20W/40W and its power light. What I did is replacing that stupid iron with a power strip so I can use any iron I like.
3) Always use rosin core solder only and the thinner, the better. Rosin is the most important for soldering. You should always see rosin smoking during a soldering, otherwise either the tip is too hot or rosin is not applied adequately. You should never do soldering without rosin or rosin core solder.
4) Always pre-coat each of the two parts with solder before solder them together. Even all the modern devices have been pre-coated in the factory, you still have to pre-coat them right before soldering. If you are soldering a device or a wire onto a PCB board, always pre-coat the pad too. Don't skip this procedure, or your soldering quality is not 100% guaranteed. Good Pre-coating is all the soldering.
5) Always apply to the tip some rosin core solder, or just rosin if the tip already has enough solder, right before it touches any soldering surface. Without rosin and solder, you are not soldering, it is heating only. Even you are trying to suck some extra solder from the soldering point, you should throw away extra solder on the tip and apply a little rosin solder to the tip first. Without rosin on the tip, it can suck nothing up. If the drop is too big, or you messed up two IC pins or two pads, you should use a solder-wick tape to suck the mess or use a tooth stick to clear up the gap.
6) If possible, always use the tip to heat the point and feed rosin core solder to the point at the same time while soldering or pre-coating. Rosin core solder feeding should be as fast as possible. Unless you have to, do not apply solder to the tip first and then point the tip to the soldering or pre-coating point without feeding some more rosin core solder. In the latter method, you should let the tip touch some rosin core solder first and, immediately, while it is still smoking, point the tip to the soldering or pre-coating point. A soldering or pre-coating would not be a good one if there was no rosin smoking around.
7) Never solder a point longer than 3 seconds (1-1.5 seconds, for micro-soldering). Or, you'll burn something. If it is not solder well, wait at least 10 seconds before you do it again. After removing the tip away from the point, keep holding the parts together at least 3 seconds to let them cool down and combine together solidly. Do not blow to them to help cooling, which makes the drop look rough.
8) All commercially available de-solder tools do not work and put your PCB boards and components in danger of heat. The best too for de-soldering is your mouth. Not kidding! Heat the point with a iron for about 1 second, blow as hard and close as you can, take the iron away, then stop blowing. This procedure is guaranteed to work after some practice on right timing. Use a solder-wick tape or a tooth stick to clear up extra solders. Use a sharp tooth stick to remove solder out of a hole. Buy a bottle of tooth sticks - they are very cheap and, unlike metal tools, they don't do any harm to PCB boards and wires.
Having these points in your mind, now let me give you an example. Assuming you are going to solder a wire to the pad of pin 57 showing in picture of L70 overclocking. Here is the correct procedure:
1) Pre-coat the wire's tip. The tip should be as short as possible, 1mm in this case. To pre-coating the tip, fix the wire on your table, heat the tip and feed some rosin core solder to coat the entire tip. This procedure should not last more than 2 seconds. After this coating, the tip should look shining. If not, do it again after 10 seconds or longer. Don't go further without a perfect pre-coating of the wire's tip.
2) Pre-coat the pad on the motherboard. Point the iron's tip to the pad, touch and heat it and feed to it with some rosin core solder immediately. This procedure should last about 1 to 1.5 seconds only and you should then see a shining silver drop on the pad. If you did not see such a drop, do it again 10 seconds later. Don't go further without getting a perfect pre-coating of this pad.
The above two steps are the most important. If you did them well, your soldering will be guaranteed to be a successful one and good one.
3) Aim the pre-coated wire's tip to the pad and hold it firmly with your left hand. Then let the iron tip touch a little bit of rosin core solder, point it to the pad, touch and heat them for less than 1 second. It is done.
You should do some exercise before your touch the precious motherboard which is just too expansive to be used to learn soldering. You should be able to do ordinary soldering within one day or so, but it takes years for you to be able to handle very tricky soldering and especially de-soldering (that's why I can charge $40 for soldering a single joint :;) ).
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