[hpsdr] OZY reflow blows up the board

[Scott Cowling]

Hi Horst,

I have asked our CM for the temperature profile that he uses to reflow the 
boards. I will get this from him on Monday and forward it to the list.

He says that they heat the board up gradually through 7 "zones", ranging 
from 100C in zone 1 through 190C-210C for zones 6-7 (the reflow zones). The 
board stays in the reflow zones for 30 to 60 seconds and then proceeds 
through three cool-down zones to bring it back down in temperature slowly.

In order to char the material the way you have done, I would guess that you 
would need over 100C hotter than 220C.

What are you using for your reflow oven? How do you determine that the 
temperature is 220C?  Do you attach thermocouples to the board to determine 
the temperature profile?  How long do you leave the PCB at the elevated 
temperature?

We have built hundreds of boards at 210C or a bit higher, and have seen 
nothing like what has happened to your board.

73,
Scotty WA2DFI

At 22:01 2007-05-05 +0200, you wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Hi HPSDR DIYers
>look what happened to my OZY board during reflow.
>
>At about 195 degrees Celsius (383 F) the board started to pop and stink.
>Reflow temperature was 220 degrees Celsius (428 F).
>This is the result:
>Decoloration
>http://www.needles.de/HPSDR/decolor.jpg
>
>Delamination
>http://www.needles.de/HPSDR/delam.jpg
>
>Popcorn
>http://www.needles.de/HPSDR/pop.jpg
>
>Delamination side view
>http://www.needles.de/HPSDR/delam-side.jpg
>
>Here an example of a board treated exactly with the same temperature 
>profile about 10
>minutes after OZY:
>http://www.needles.de/HPSDR/compare.jpg
>
>Nothing happened here.
>
>Very disappointing. Anybody out there with a solution????????
>
>
>73
>Horst
>DL6KBF
>
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