Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Embrittlement Sucks.....

Ben Salisbury

#14606

Embrittlement Sucks..... | 21 August, 1998

It's been one hell of a week.... From personal experience, what are the most common causes for embrittlement of the solder joint? I just need to make sure I've got all my bases covered. thanks -Ben

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Earl Moon

#14607

Re: Embrittlement Sucks..... | 21 August, 1998

| It's been one hell of a week.... | From personal experience, what are the most common causes for embrittlement of the solder joint? I just need to make sure I've got all my bases covered. | thanks | -Ben Right on. Yago sangria. Chili conceso. That's all Spanish for embrittlement sucks big time. Dissimilar metals, when bonded can become brittle. In solder joints, any metal not compatible with the solder medium can cause embrittlement. Again, look at chart 5-1 in ANSI/J-STD-001B and observe, behold, and look closeley at the amounts of various metals causing contamination to the tin/lead alloy - that is used to bond two metal surfaces with higher melting temperatures than the solder. When these contaminates exceed specified amounts, solder joints become brittle. Also, in the same breath, intermetallic formations effected to lesser or greater degrees, during controlled or less controlled soldering operations, respectively, can cause initially unacceptable solder joints. More importantly, these joints will fail over time due to continued intermetallic growth (with dissimilar metals the growth continues over time) under thermal or mechanical stress, or both. Earl Moon

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Jeff Sanchez

#14608

Re: Embrittlement Sucks..... | 26 August, 1998

| | It's been one hell of a week.... | | From personal experience, what are the most common causes for embrittlement of the solder joint? I just need to make sure I've got all my bases covered. | | thanks | | -Ben | Right on. Yago sangria. Chili conceso. That's all Spanish for embrittlement sucks big time. | Dissimilar metals, when bonded can become brittle. In solder joints, any metal not compatible with the solder medium can cause embrittlement. Again, look at chart 5-1 in ANSI/J-STD-001B and observe, behold, and look closeley at the amounts of various metals causing contamination to the tin/lead alloy - that is used to bond two metal surfaces with higher melting temperatures than the solder. When these contaminates exceed specified amounts, solder joints become brittle. | Also, in the same breath, intermetallic formations effected to lesser or greater degrees, during controlled or less controlled soldering operations, respectively, can cause initially unacceptable solder joints. More importantly, these joints will fail over time due to continued intermetallic growth (with dissimilar metals the growth continues over time) under thermal or mechanical stress, or both. | Earl Moon

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