Author Topic: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs  (Read 479 times)

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Online mikeselectricstuff

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Question for metallurgists:
I'm fixing two (ENIG) PCBs together with nylon snap rivets for a mechanical +electrical joint.
Using a crinkle washer between to maintain tension for a reliable contact against any long-term creep etc.
I can buy A2 stainless or beryllium-copper crinkle washers - which would be best and why?
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Offline voltsandjolts

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #1 on: June 13, 2018, 11:13:27 pm »
Beryllium-copper is toxic in some forms. Don't file the washers!
 

Offline hayatepilot

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #2 on: June 13, 2018, 11:22:43 pm »
It depends on how much current has to pass through the joint. Stainless has a pretty bad electrical conductivity.

Even better are toothed lock washers (also known as serrated washer or star washer) like those used on grounding lugs.
 

Offline free_electron

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #3 on: June 14, 2018, 12:59:55 am »
If it really must be reliable : PEM nut. punch it in the board and done.

i would not trust dissimilar metals. depending on environment and what is in the air ....
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Offline donmr

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #4 on: June 14, 2018, 01:31:23 am »
Are you passing current through this washer or just using it to hold the boards and some connectors together?
 

Offline steverino

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #5 on: June 14, 2018, 04:39:33 am »
Interesting.  I never heard of a PEM nut.  Here's some info from a google search:

https://www.pemnet.com/fastening_products/pdf/kdata.pdf
 

Online dmills

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #6 on: June 14, 2018, 05:44:57 am »
Wurth do a version in 1mm height increments which can sometimes be convenient (IIRC PEM SMT ones are in 2mm height increments).

Regards, Dan.
 

Offline langwadt

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #7 on: June 14, 2018, 06:06:06 am »
It depends on how much current has to pass through the joint. Stainless has a pretty bad electrical conductivity.

Even better are toothed lock washers (also known as serrated washer or star washer) like those used on grounding lugs.

star washer on a pcb sounds like a really bad idea
 

Offline chickenHeadKnob

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Re: Beryllium copper vs. A2 stainless crinkle washer for connecting PCBs
« Reply #8 on: June 14, 2018, 07:44:42 am »
Nylon is so stretchy that even a bellville washer would be unreliable over time. fix the boards together with standard steel or brass hardware and loctite, or use locknut.
 


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