[SOLVED] soldering traces for more current

[Electro nS]

Ok guys , i have tested copper traces on the pcb with and without heavy soldering and the results are great.

but i am concerend about the excessive heating of the PCB and the SMD parts already soldered by me ( or by machines later )



i am using a strong 100W iron , because smaller irons donot do the job well
so will this hurt the rest of the board same or on the next layer ?

 

[tpetar]

Ok guys , i have tested copper traces on the pcb with and without heavy soldering and the results are great.

but i am concerend about the excessive heating of the PCB and the SMD parts already soldered by me ( or by machines later )

You can use other side of PCB with thermal vias for better cooling, and of course to increase current capacity.

i am using a strong 100W iron , because smaller irons donot do the job well
so will this hurt the rest of the board same or on the next layer ?

No need for 100W iron, you can finish all with 30-40W, and temperature setup during soldering is much more is important. 100W is for house gutters. :smile:

 

[Ernstine]

How great is great? Did you quantify it by doing before and after measurements? If so please share them!

 

[Centmo]

The key to using a soldering iron for this kind of work is to use a large tip (so you won't need such a powerful iron). The tip is the heat revervoir, and if it is too small, it will cool down too quickly once you apply it to the trace. A large tip will hold its heat and get the job done. It's good to have a couple irons - one with a small tip (0.062") for smaller SMT, and one with a larger tip (.125") for parts with large heat sinking pads (e.g. TO-220), and these kind of jobs. Screwdriver style (a.k.a chisel) is the best overall tip type IMHO.

 

[Electro nS]

How great is great? Did you quantify it by doing before and after measurements? If so please share them!

yes offcourse i am a scientific test , because i wanted to get exact measurments . i used the 4 points method , where constant current is applied and voltage is measured across a 5mm trace on pcb which is 20cm long.
4 traces where made : 1 no solder
2 meduim solder about 1-2mm thickness
3 heavy solder about 3-3.5mm thinkness
4 soldered a AWG10 wire + full solder over the traces { note in this case the pcb was bended becasue of the extreme heat }

i assumed that case 1 is good for 12.5A ( i calculated that using online free calculater)
case 2 was good for 40A (becasue i found that reistance decrease by factor of 3.6..)
case 3 was good for about 80A
case 4 gave me insane result where it could handle 370A (i know that it is not realistic , but you cannot arguee with numbers, the resistance decreased by a factor of 30)

This test was done on 1A constant current using linear power supply . these might change at real circuit high current since the effect of tempreture on resistance . But donot you consider that great result ( take case 2 and 3 ) , what do you think Ernstine ? hope that helped

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thanks guys , i think the best option is a temp controlled big tip iron .

but i still haven't got the answer to the question . so i will try to qlarify .

is excessive heating a trace NEAR a componnet or on the opposite side (not a pad of lead of part) harm the component after it has been soldered ??

how can i know that i am on the safe side ? or i am indangering the parts.

 

[Centmo]

Well, you could do a test. Solder a temperature probe (bead) to one of the component pins (say, a ground pin, or the pin closest to the rework). Get something that you can plug into your multimeter, if it is temp probe ready, like this:

http://www.extech.com/instruments/product.asp?catid=68&prodid=321

Then watch how hot it gets while you do your heavy soldering. Most components when they are soldered in a reflow oven get up to 230-255C max for ~20 seconds max, so you wouldn't want to exceed this. Even that temperature for that amount of time would make me a little uncomfortable.

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...here is the standard temperature profile components go through in a reflow oven:

http://www.cypress.com/?docID=29889

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...I'll also add that when doing heavy wire soldering, I'll turn my iron up to 700-750F.