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Problems applying the right amount of Solder Paste
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Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Tue Feb 16, 2016 8:27 pm

As you can see from these photos, I'm having a hard time applying solder to pads for QFN parts with 0.5mm and below pad sizes. The stencil is 5mm thick, hence the pile.
If I were to placed a component on these pads and use my re-flow oven, I will surly get bridging.

And help would be greatly appreciated.

image1.jpg
image1.jpg (611.9 KiB) Viewed 778 times


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20160213_131150.jpg (472.27 KiB) Viewed 778 times

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Re: Problems applying the right amount of Solder Paste

by franklin97355 on Sun Feb 28, 2016 1:05 am

Not a lot you can change if you can't get the proper stencil.

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Sun Feb 28, 2016 12:31 pm

What is the proper stencil?

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Re: Problems applying the right amount of Solder Paste

by franklin97355 on Sun Feb 28, 2016 1:34 pm

One that has the proper thickness for the pitch of the pads on the PCB.

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Sun Feb 28, 2016 8:27 pm

This is the thickness suggested. There must be something else.

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Re: Problems applying the right amount of Solder Paste

by franklin97355 on Sun Feb 28, 2016 8:42 pm

Then you are not holding the stencil to the board tight or squeegeeing hard enough.

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Sun Feb 28, 2016 8:50 pm

Notice the surrounding pads, you'll see that this problem does not happen to the other pads. Have you ever used a stencil?

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Sun Feb 28, 2016 8:59 pm

To be fair, these pads are associated to DFN type parts. Thus, less than 1 mm on each pads dimensions and from the configuration of the pads, not possible to hand solder; since the pads are under the part's body.

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Re: Problems applying the right amount of Solder Paste

by franklin97355 on Sun Feb 28, 2016 9:07 pm

I'm out of ideas then.

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Re: Problems applying the right amount of Solder Paste

by juku on Fri Mar 18, 2016 7:03 am

SMD stencils are typically 0.1mm thick.

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Fri Mar 18, 2016 2:52 pm

Where do you get 0.1mm thick stencils?

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Re: Problems applying the right amount of Solder Paste

by adafruit_support_mike on Sun Mar 20, 2016 11:05 pm

There are several companies online that will make them for you, but they run about $30-$40 per stencil.

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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Mon Mar 21, 2016 3:52 pm

So far, only 3mil is available. Again, which company does less then 1mm?

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Re: Problems applying the right amount of Solder Paste

by juku on Mon Mar 21, 2016 8:44 pm


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Re: Problems applying the right amount of Solder Paste

by jamesbuchanan1220 on Tue Mar 22, 2016 2:21 pm

Thank you, I'll look into them.

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