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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


No clean with higher SIR values

Views: 1545

#42033

No clean with higher SIR values | 8 June, 2006

I would like to use a no clean paste on an assembly, but seams most no cleans only get to SIR values of 10 E10 or so. Can anybody recommend something with a higher SIR residue? Peter

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Bob R.

#42102

No clean with higher SIR values | 12 June, 2006

What's wrong with 10E10? 100 Mohms (1E8) is a pretty standard lower limit so you're a few orders of magnitude better than needed.

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#42107

No clean with higher SIR values | 12 June, 2006

Customer requires 10 E 13, then humiseal applied to take air out of the equation. This is primarily required on a 1Meg High Voltage resistor divider PR

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Bob R.

#42150

No clean with higher SIR values | 13 June, 2006

Wow, good luck. None of my test results would be helpful since we use IPC-B-24 test boards as received from our board suppliers so we have a clear understanding of what we're shipping customers, not necessarily paste performance alone. We'll only clean them prior to SIR if it's part of our production process for the paste under evaluation. We usually put a few bare boards in with the pasted boards and the best I'm seeing is about 5E10 for bare boards. The better pastes track pretty much right with the bare boards as far as resistance at each temp/humidity condition. I haven't had SIR run in a couple years so I don't know what the current batch of pastes look like. I'm actually about to start evaluating some later this summer.

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