Just be sure the cost cutting model includes the added expense of
occasionally replacing delaminated PWAs when the low Tg material is
soldered at the higher lead free soldering temperatures.  If that is
factored into the model, I think management will see that the high Tg
material leads to lower costs overall.

Kirk Mueller
Raytheon Systems Co.








Steve Collins <[log in to unmask]>@IPC.ORG> on 08/01/2000 07:57:39 AM

Please respond to "Leadfree Electronics Assembly E-Mail Forum."
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To:   [log in to unmask]
cc:
Subject:  [LF] Cost of base materials & Lead-Free


Thanks to everyone who commented on my question yesterday "LGX file
extension". Today I have another one.

For the past 10 -12 months since incorporating the IPC-4101 Specification
for Base Materials for Rigid and Multilayer Printed Boards and implementing
Immersion White Tin as our surface finish and looking toward using
99.3Sn/0.7Cu for our wave soldering & 95.5Sn/4.0Ag/0.5Cu or 96.5Sn/3.5Ag
for our Reflow soldering I have been specifying the slash sheet 24 (Tg
150°C - 200°C) as our base laminate. The reason was to get a higher Tg
material in order to withstand the higher manufacturing process
temperatures (wave & reflow soldering). This is now in danger due to cost
reduction programs being looked at internally. Typically in the past what
we called out was a generic form of FR-4 and what we got was similar to
slash sheet 21 (tg 110°C Minimum).

I'm in the process of calculating just what the material cost differences
from our vendors is but wanted to put this out to the other industry
experts also.

Now for my questions, are any of those people looking at the "Lead-Free"
going through similar experiences. Was my concern for the higher temps in
manufacturing realistic. Was my approach realistic.


Sorry if this sounds pleading but with the changes around here I'm
concerned whether my ideas hold credibility or not.

Thanks in advance for any comments.

Steve
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###############################################################
Please visit IPC's Center for Lead-Free Electronics Assembly
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For technical support contact Keach Sasamori [log in to unmask] or 847-790-5315.
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