At 12:53 PM 4/09/98 +1200, you wrote: >A 25 watt iron is fine as long as you are adequately careful. A low >wattage iron with a small tip (or an iron of any wattage at all with >temperature control) will make soldering easier. > >Don't overheat the part and you'll be OK. >Gluing is not at all desirable as a way of electrical connection. The >recent discussion related to fastening components in place in unusual >or prototype circumstances. > >At the risk of being flamed for abominable soldering practice ... > >{{Solder shields up}} > >Soldering: > >Temperature controlled irons are usually best. Uncontrolled irons >with physically (and therefore) thermally large tips will rest at >well above soldering temperature and then dump energy to a small cold >component leg very quickly. Overheating is fairly likely if you are >not experienced. > >1. Have iron tip clean with usually a single solder point near >tip. >2. Wipe iron on damp sponge (sea sponge often used. Plastic dies). >3. Tin tip if required (occasionally) by applying solder lightly >to soldering point. >4. Apply iron to one side of component "leg". >5. Allow component leg to heat to soldering temperature. >6. Apply solder to opposite side of component leg until it melts >(almost instantly if you've followed 4 & 5) and allow a SMALL amount >of solder to apply to joint. >7. Leave iron in place for a very slight time to ensure all is at >solder temp and then remove tip. >8. Do not move joint until solder is set. Too cold a joint or >moving the joint while setting will lead to so called 'dry joints" >which will cause endless trouble. these are easily spotted by colour >and texture. make a few to see what they look like. Leaving iron on >too long will apply excess heat to the component with risk of damage. >Too little solder leads to a possible bad joint. Too much solder >risks short circuits and makes it hard to be sure of joint quality. > >In practice I don't strictly follow steps 4 to 7 - after a few >decades it becomes a continuous process (sort of). heat joint >partially and then feed solder in at iron/component leg junction a >little to improve iron heat transfer, wait a moment then add a little >more solder, wait a while more and remove iron. This is not what the >books say and following steps above is probably a good start. > >No doubt there will be numerous PIClisters keen to critique this >technique. > >{{Solder shields down}} > >-----Original Message----- >From: Matt D K >To: PICLIST@MITVMA.MIT.EDU >Date: Thursday, September 03, 1998 11:34 PM >Subject: 25 watts > > >>I'm ready for my first PIC application and am worried about my 25 >watt >>sodering iron frying it. Is the PIC that sensative to heat? Is glue >a >>better alternatie? >> >> Matt K >> "Just your not so average >electronics >>geek" >> Hello Matt. Not so your average electronic geek, This is a good response, but I have noticed a thing or two missing. Most semiconductor components can handle a soldering lead temperature of X degrees (270 to 300 celsius) for a period of 10 seconds (You will see this period and temperature stated in device data)(Other components like cheep switches can not). Now 10 seconds is quite a long time! You will have more problems with dry joints attempting to solder too quick, than what you will soldering for too long. By this I mean that the chance of damage is quite minimal with too much heat than with not enough (Here come the critics). But to reduce this chance, and if you have problems with your soldering techniques (Assuming that your soldering the IC directly to the board), then touch the IC (TOP only) after you have finished each leg (Of course watch out to ensure that you don't burn your finger). If you can hold your finger on it, then it is not too hot, and you can solder the next pin (This is a very basic rule of thumb). Other things to keep in mid, is solder the ground pin first, then the power pins. One other method is to diagonally solder ie. Pin 1, Pin 11 (Assume 20 pin device) Pin 2 Pin 12, Pin 3 pin 13 etc. As for your question 25 watts is quite OK for small pads on a single sided and double sided board (Say around 2-3mm in diameter) A quick rule of thumb for soldering iron wattage is if it can not melt solder next to the tip when the tip is in good thermal contact with both pin and land in 4 seconds, then the iron is too small. One other thing is that there is nothing wrong with adding more solder latter ie. You can revist the solder joint if your not satisfied. If you are worried, then as one poster noted, use an IC socket. I hope that all this information from posters help. Good Luck, and enjoy. Dennis