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June 2006

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Subject:
From:
"Tempea, Ioan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Tempea, Ioan
Date:
Wed, 21 Jun 2006 08:56:36 -0400
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Hi Technos,

for a couple of days I see occurences of blowholes in the joints of, guess what, SMT 0603 resistors.

The reflow recipe did not change and we're talking about 2 different established products, we have run many of each before. One is WS, the other one no-clean. Each one uses different brand of solder paste, SnPb.

I have changed the paste with fresh one, no positive results. I have changed the reels with different date codes, Bingo! But even the "bad" parts were quite fresh, less than one year old. One of them is pure Sn plated, don't know about the other ones.

The question is: where on Earth can humidity stay in a ceramic resistor? What else can be the cause of the blowholes? Did not bake the boards, since changing the components worked, so I guess the PCBs are out of the hook...

Thanks,

Ioan

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