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Is This Corrosion?

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Is This Corrosion? | 20 January, 2009

Is this Corrosion?

We found our boards with this issue 45 days after they were delivered to us from supplier.

The board finish is HAL Leaded. But I noticed that the corrosion like issues are coming form the tiny via holes with SILVER EPOXY FILLING. Also noticed some exposed copper on the filled vias taht were not properly penetrated during HAL process.

Any idea what are the possible causes of this? We have the same finished boards without the silver epoxy fillings that are in our stores for almost 4 months and they do not have this problem.

Can you help me with some info on what is it and the possible root causes of this issue?

thanks and regards,


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Is This Corrosion? | 20 January, 2009

For lack of a better description, we'd say, "Yes, that could be corrosion." Regardless of what you call it, it looks nasty and should not be allowed on bare boards of any sort. Based on your picture, we can't tell you whether it's related to your conductive via fill or not. But that you have solderability issues with both filled and unfilled via, it indicates that these probably is some common source.

We'd reject these boards at incoming and send some of them to: * Supplier * Outside failure analysis laboratory ... for analysis

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Is This Corrosion? | 20 January, 2009

Thanks guys.

They are seen on some of the pads too. What will happen if I continue to solder them and I got a good solder joint formation? Will the pad continue to erode or corode in due time? or the solder that will recoat its surface will prevent the internal corrosion?

thanks and regards,

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Is This Corrosion? | 20 January, 2009

We'd guess that since your board fabricator could not remove this stuff with it's HAL-leaded process, you're unlikely to remove it with your soldering process that is likely to be pansy-ass compared to your fabricator HAL process.

Hey, why not run a bare board through your process and see what it looks like, wudya loose?

Do you think these boards looked: * Like this upon receipt, but were misinspected / not caught * Different at receipt and changed appearance while in the stock room

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Is This Corrosion? | 21 January, 2009

hi davef,

good idea! run one sample and see waht happens with the solderability.

yeah we received them good and just happened after 45 days in our stock room. I suspect that during the HAL process some parts of the vias with epoxy fillings were not fully covered with solder. that is if I'm correct about their process which is to apply the fillings prior to HAL.


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Is This Corrosion? | 21 January, 2009

My frsh information from the fab is that:

"Its Just A Bleedout"

as to why? no response yet.

as for "are they corrosion?" no response yet.

as for "are they harmful and will they affect the reliability and integrity of the product?". no reply yet.

If this is a Military Product is it acceptable?


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Is This Corrosion? | 22 January, 2009

To close the issue: PCB Fab had a look on the PCB's then decided to recall them back...including PCB's that's already been built...


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