This is a 7 zone Convection oven. We have adjustable cooling fans at the 
end to control cooling. Effectively this gives an 8th zone.

Leif Erik Laerum
Quality Assurance Manager
Texas Memory Systems
[log in to unmask]
Tel: (713) 266-3200 x468
www.texmemsys.com



Joyce Koo wrote:
> What is your reflow oven? Convection with x zone? 
> --------------------------
> Sent using BlackBerry
>
>
> ----- Original Message -----
> From: TechNet <[log in to unmask]>
> To: [log in to unmask] <[log in to unmask]>
> Sent: Tue Sep 08 08:45:13 2009
> Subject: [TN] Non Wetting Problem
>
> Technetters,
>
> We have a problem with non wetting on a very specific component. Only 
> this part exhibits the problem. These are double stacked FLASH TSOP 
> components that are stacked from the vendor.
>
> http://stevezeva.homestead.com/files/test6.jpg shows the same pin as in 
> test7 but enlarged.
>
> http://stevezeva.homestead.com/files/test7.jpg shows the most extreme 
> case with no heal fillet.
>
> http://stevezeva.homestead.com/files/test8.jpg hows another example with 
> a heal and toe fillet, but there is a crease on both sides of the pin
>
> The process is lead free. Our peak is about 245 for these components. We 
> hold peak for 20-30 sec. TAL is about 70.  I can not run much hotter 
> since there are large (676 pin) BGAs that reach 260. We have been all 
> over the spectrum with respect to profile. My revision log shows I have 
> done about 25 different ones. We have tried long soak, medium soak and 
> short hot ramp to spike. We have also experimented with different solder 
> types. The winner so far is a Water Soluble SAC305. The best results 
> (least defects) do come with a shorter RTS profile. The FLASH vendor 
> recommends we peak and hold at 255 -260 for ~30 sec. I am not able to do 
> that since then the 672 pin BGAs (3 of them) reach well above the 
> recommended temp of 250. With the current profile they are already at 
> 260. As you have already guessed, there is a 10 - 15 degree delta on 
> this board that is very heavily populated with these TSOPs. This board 
> has in other words a large mass. This condition does result in loose 
> pins. It is not the same pins every time either, so it does not appear 
> to be related to the ground planes. This is a 14 layer .062 board.
>
> The questions:
> 1. Any obvious remedies to eliminate the problem?
> 2  Anyone with similar experience?
> 3. How do you like my pictures?. I am trying out a new tool. This pics 
> are at 45X.
>
>
>   

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