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Reply To: | TechNet E-Mail Forum. |
Date: | Thu, 6 Sep 2001 09:20:35 -0400 |
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Jim, thanks I'll start looking into this today! However, it appears from
testing we are doing that the warp occurs during ramp up - we have heated
some of these chips in an oven to 125 deg C, allowing them to stabilize,
and we measure warp upwards of 6 to 8 mil ... at this point, the solder
balls of the BGA are not even touching the solder paste.
Bill...
At 06:48 AM 09/06/2001 -0600, you wrote:
>Bill,
>If you have not already, look at the cooling rate on your reflow oven. I
>solved a similar similar warpage problem by reducing the solder cooling rate
>to 1 deg C/second. I had to modify the blowers in the cool down section to
>achieve that rate. I found my oven was designed to blast the top of the BGA
>with cold air while the solder was still liquidus. It provided for high
>speed production, but was warping some of the BGA's.
>
>Jim Kittel
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