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DPAK drop @Second reflow

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#64391

DPAK drop @Second reflow | 31 May, 2011

HI All,

Please kindly advice me, I have project that it has DPAK part (MPN:SUD25N15-52 E3 Plating:100% Sn matte)which locate on bottom side (1st reflow), Good wetting for 1st reflow..

but .. when I run Top side (2nd reflow).I found that this DPAK drop in reflow oven or insufficient solder (after passed reflow oven)too much.

I can't add glue for this part because it'll have void in ground terminal. My reflow profile is normal as spec.

Please advice me to solve this pronlem .. Thank you

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#64410

DPAK drop @Second reflow | 2 June, 2011

We don't expect properly soldered first-side DPAKs to fall from the board during second-side reflow.

The ratio of weight to solder surface area for a DPAK is 1.32 gm per in^2, which is well within the limit of 44 gm per in^2. [Search the fine SMTnet Archives for more on this calculation. Include zarrow in your search terms]

The initial ideas as explanation are: * There is not enough solder on the DPAK pads * Solder on the DPAK pads is not properly reflowed during first-side reflow * DPAK is being moved or dislodged after second-side reflow before the solder solidifies

If all else fails, you might be able to use chip bonder along the edge of the component after the first reflow to hold it in place

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#64489

DPAK drop @Second reflow | 15 June, 2011

check your reflow chain. it maybe vibrating causing DPAK to fall at second reflow.

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#64491

DPAK drop @Second reflow | 15 June, 2011

If you have the ability to control top and bottom zone temperatures verify that the difference in your peak area is 10 to 20 degrees. This will depend on the ovens capabilities.

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