Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Chris Jackson

#11777

Paste-in-Hole | 22 April, 1999

I need to know if there are any special component pad designs that need to be considered when evaluating paste-in-hole? We have a few through hole connectors that are good candidates to place pre reflow. Does anyone have sugguestions. Thanks Chris

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John W

#11778

Re: Paste-in-Hole | 22 April, 1999

| I need to know if there are any special component pad designs that need to be considered when evaluating paste-in-hole? We have a few through hole connectors that are good candidates to place pre reflow. Does anyone have sugguestions. | Thanks | Chris | Chris, Generally the pad's only need to be slightly larger but I have found some connectors and headers that have small disk's on the thro' hole part of the component that sit's on the pad once pasted that improve the thro hole reflow of the paste. Try looking at the Samtech web site.

good luck

John

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Scott Davies

#11779

Re: Paste-in-Hole | 23 April, 1999

I need to know if there are any special component pad designs that need to be considered when evaluating paste-in-hole? We have a few through hole connectors that are good candidates to place pre reflow. Does anyone have sugguestions. Thanks Chris ----------------------------------------------------------------- Chris,

We've been doing thru-hole reflow assembly with connector blocks for a few months now. The product wasn't specifically designed with paste-in-hole in mind, i.e. the pad sizes are no different to those for a wave soldered block. The success of the process is dependent on getting enough paste on the board, by enlarging the stencil apertures, using a slightly thicker stencil (0.008" instead of 0.006") and experimenting with squeegee angle, print speed and pressure to get the best result.

So for most components, pad design is probably not too much of an issue. However, if the component has flat leads instead of cylindrical leads, we have found that the quality of the solder joints is not so reliable. I think this is probably because the surface tension of the paste during reflow pulls it to one side of the flat lead, leaving a void on the other side. We are currently trying to come up with some pad designs to overcome this problem.

Good Luck Scott

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