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Parts Blowing off in Reflow Oven

Ryan

#35234

Parts Blowing off in Reflow Oven | 29 June, 2005

We have a new Heller 1809 EXL reflow oven and when we run MELF�s or Aluminum Electrolytic Capacitors through the oven they are being blown off the pads. I have verified that the placement is good before reflow. I verified that they are pushed down into the paste. I also verified that the reflow profile was correct. I ran boards through the oven with the hood open 2 inches so I could watch the boards travel through but whenever I do this all the parts stay on the pads. There are no height clearance issues. We have run the same boards with the same parts for years on an older oven with no problems. Has anyone else had this problem? Any solutions?

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GS

#35236

Parts Blowing off in Reflow Oven | 29 June, 2005

Start from this: - check the air flow speed, if too much it can help to get components moved/blowed away. - Other cause (not so often)it could be moisture in PCB, so when degassing, may be trough vias, the pressure could blow away components.

Regards GS

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#35243

Parts Blowing off in Reflow Oven | 29 June, 2005

investigate the part ,maybe mositure could get into the part!

vendor,datacode

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bobpan

#35246

Parts Blowing off in Reflow Oven | 30 June, 2005

Can you run the board on the other side of the oven??? Can you turn on the oven and set the heat real low and feel the air blowing down over the heaters???? You may be able to tell something is going on that way. Also make sure vibration isnt causing the problem....i have seen that before.

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slthomas

#35248

Parts Blowing off in Reflow Oven | 30 June, 2005

Is this happending consistently with every board?

I guess if it is (so is easily reproduced), I'd run boards in with the lid down, then open it when the tunnel is full and see which boards still have all the parts in place. At least then you'll know where it's happening.

Does this oven have control over blower speed in all zones?

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#35250

Parts Blowing off in Reflow Oven | 30 June, 2005

Ryan, I have never seen an oven "blow" parts off the pads. Whenever I have seen parts come off the pads in the oven, it was because the mesh conveyor or edge chain was jumping a sprocket tooth.

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dougs

#35252

Parts Blowing off in Reflow Oven | 30 June, 2005

i've seen ovens blow the parts off of boards, but only the older style air amplifier types, not seen a fan driven oven do this. is the oven in question air amp or fan???

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#35253

Parts Blowing off in Reflow Oven | 30 June, 2005

Its been my experience that a "dot" of glue on the center of the part is needed for "barrel" type components.

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K

#35254

Parts Blowing off in Reflow Oven | 30 June, 2005

I'm not familiar with this particular oven, but have seen this problem once before. As it turned out there was a flexible curtain near the end of the reflow tunnel on the oven. Some very fine strands had frayed from the curtain and were catching on the components as the solder was still molten.

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John

#35256

Parts Blowing off in Reflow Oven | 30 June, 2005

I had the same incident before, and like GS pointed out, the degassing from the via under the component was responsible. The via was covered with solder mask, but it burst open during the reflow.

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KEN

#35257

Parts Blowing off in Reflow Oven | 30 June, 2005

1. Migrate to horse-shoe pad design. 2. Verify your furnace is level. 3. Verify your chains are not jerking around. 4. Speed control for fans / gas amplifiers are correct or normal? 5. (this happended to me once) Make sure you don't have any furnace control T/C wires "drooping" down and touching the boards.

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#35269

Parts Blowing off in Reflow Oven | 1 July, 2005

I had similar issue with our new 1809 Heller Oven recently. It was blowing off some of the lighter parts. I tried kitchen exhaust fan mesh screen (you can pick this up at your local hardware store). Once I knew it was air flow issue, I played with blower speed control. This oven has 3 speeds option to control blowers.

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smt_pro

#35270

Parts Blowing off in Reflow Oven | 1 July, 2005

We had this happen in a Heller 1808 oven when we placed Tant-A caps in glue (bottom side / no paste). We had our oven retrofitted to control the zone blower speeds. No more problem.

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#35496

Parts Blowing off in Reflow Oven | 14 July, 2005

I too experience it too component being blown out of the pad also using heller 1800. In my case I also did check entry and exit of reflow so far no obtruction. Also checked profile setting also ok. Mine is a 0603 Chip capacitor... but problem is only encountered on specific location... many components are mounted using same part no. I also checked if there may be other components near the cap. causing it to be blown away ... but it seems near by components do not show openings formed by moisture exhaust...?? Until now it also is a puzzle to me..

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