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Suitable temperature for solderjoint ?

#8523

Suitable temperature for solderjoint ? | 15 November, 1999

Hello everybody, engeneering came up with following problem: Considering worst case the get a temperature at a component (Resistor 0805) of 109�C and 99�C at the solderjoints. As a rule of thump I said that the max. suitable temperature for the solderjoint should be half the liquidous temp. which in this case is 180�C. They want to know the exact limits for FR4 and the solderjoints because they are afraid of calling back all PCBs for improvement. Now , can anybody name specs, regulations or exact figures on that topic ?

Thanks in advance Wolfgang

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Dave F

#8524

Re: Suitable temperature for solderjoint ? | 15 November, 1999

Wolfgang: Sounds like gluteus maximus protection time.

1 "Maximum suitable temperature for the solder joint should be half the liquidous temperature" is a good rule of thumb. Where it came from, I don�t know. One place I�ve seen it repeated is: Hwang "Modern Soldering Technology �" 3.5.1. 2 Coombs, 8.8.5 talks about FR4 maximum continuous operating temperature of 130�C for electrical parameters and 140�C for mechanical parameters, but that�s pretty generic stuff. Realistically, your board supplier probably knows more about this than anyone. 3 Solder joint strength will vary with lead geometry, solder volume, solder type, lead metal/metallization, the way the product is operated, the way the test is done, etc. Realistically, you probably know more about this than anyone.

My2�

Dave F

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#8525

Re: Suitable temperature for solderjoint ? | 16 November, 1999

Wolfgang: A snipet of information that maybe more on track that the previous babbling:

The temperature limit for FR4 is 130�C according to UL746(?)

Good luck

Dave F

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