[hpsdr] OZY reflow blows up the board

[H. Gruchow]

Hi all,
thanks very much for your input regarding the reflow failure of OZY.

One thing is for sure: I can trust my reflow oven. OZY was the 32nd board which I treated 
in the furnace. Mostly I use it for de-soldering boards in order to get the parts. But 
also soldering never failed so far.

The temperature profile I used for OZY was:

1. Preheat: 1°C/s from room temp to 110 °C. Usually takes about 2 min.
2. Soak: 90s from 110°C to 150°C
3. Dwell: from 150°C to 180°C
4. Reflow: from 180°C to 220°C time 60s
5. Cooling in the oven with door open from 220°C down to 45°C before removing the board 
from the oven.
The max temp my oven can reach is about 270°C because above that it is switched of by a 
security thermo switch.
This all is controlled by a thermocouple and microcontroller.

I do not know what happened here. I have blisters all over the OZY board. My guess is 
moisture. But that does not explain the heavy de-coloration of the silk screen print into 
almost brownish color.

One thing is for sure: the other boards will be hand-soldered. I will not take another 
risk of loosing a board.
John, W9DDD, is there a spare OZY which I could order?

73
Horst
DL6KBF


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