[hpsdr] Warning on Atlas! NO HIGH TEMP WORK!

[Lyle Johnson]

>   "...laminates - even those that pass the stringent FR4 test for quality - are generally unable to withstand the much higher temperatures for lead free solders..."
> I don't understand that. It isn't "much higher", it's only a few degrees. I just had a look at this Altera document:

The delamination is a combination of slightly higher temperatures and 
much longer dwell times at temperature.  The longer times apparently 
have to do with the poorer wetting quality of the lead-free solders. The 
delamination chemical reaction is a sort of integrating process. It is 
the product of time * temperature that causes the problem.  There is no 
guarantee that t e boards *will* delaminate, but the bond is certainly 
weakened and they *may* delaminate.

There are other formulations which can withstand the higher 
temperatures, but there is presently an extra cost associated with it. 
As time goes bay and RoHS compliance becomes commonplace, I suspect the 
cost increase will go down.

I am going through this process now with my DSPx boards. I was able to 
locate a vendor in the US who is making the high-temp, gold-plated PC 
boards for only alittle more than I wa spaying for off shore boards. 
The setup costs are substantially higher, unfortunately.

In the end, we may be able to get RoHS compliant boards that are also 
suitable for the higher temperature processes for only a little more per 
board if the quantities are reasonable, say in the mid-hundreds.

73,

Lyle KK7P.


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