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Hon Choi

#11613

Pin-to-paste | 30 April, 1999

Hi all,

We're starting up tests for pin-to-paste and, well, things could be better. We're testing different pastes and we're testing different apertures rules and, well, we're still testing. It's coming close and we're getting pretty good joint now, but we've got to slow down our chipshooter so that our paste doesn't go flying out every which way. Has anyone been through this phase before? Is there a solution for this or are we the only ones with this problem?

Thank you, Hon

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Scott Davies

#11614

Re: Pin-to-paste | 30 April, 1999

Hi all, We're starting up tests for pin-to-paste and, well, things could be better. We're testing different pastes and we're testing different apertures rules and, well, we're still testing. It's coming close and we're getting pretty good joint now, but we've got to slow down our chipshooter so that our paste doesn't go flying out every which way. Has anyone been through this phase before? Is there a solution for this or are we the only ones with this problem? Thank you, Hon -----------------------------------------------------------------

Hon,

What thickness stencil are you using? If you've got paste flying around the board, it sounds like there's too much paste on there. Pin-to-paste (Intrusive Reflow, Pin-in-hole Reflow, and any other names you can think up for it) is all about striking the right balance between getting good thru-hole joints without compromising the quality of the surface mount stuff. We've gone for a marginal increase in stencil thickness (0.008" instead of 0.006"), increased aperture sizes for the through hole items, reduced apertures for the SMT pads. We're also trying a different squeegee angle (45� instead of 60�) to push more paste down into the holes for the thru-hole components.

Bob Willis has done some excellent stuff on Intrusive Reflow. I'm sure he'll be posting a reply to your question too.

Good Luck, keep us informed about how you get on with solving this problem.

Scott

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Bob Willis

#11615

Re: Pin-to-paste | 1 May, 1999

| Hi all, | | We're starting up tests for pin-to-paste and, well, things could be better. We're testing different pastes and we're testing different apertures rules and, well, we're still testing. It's coming close and we're getting pretty good joint now, but we've got to slow down our chipshooter so that our paste doesn't go flying out every which way. Has anyone been through this phase before? Is there a solution for this or are we the only ones with this problem? | | Thank you, | Hon | | ----------------------------------------------------------------- | | Hon, | | What thickness stencil are you using? If you've got paste flying around the board, it sounds like there's too much paste on there. Pin-to-paste (Intrusive Reflow, Pin-in-hole Reflow, and any other names you can think up for it) is all about striking the right balance between getting good thru-hole joints without compromising the quality of the surface mount stuff. We've gone for a marginal increase in stencil thickness (0.008" instead of 0.006"), increased aperture sizes for the through hole items, reduced apertures for the SMT pads. We're also trying a different squeegee angle (45� instead of 60�) to push more paste down into the holes for the thru-hole components. | | Bob Willis has done some excellent stuff on Intrusive Reflow. I'm sure he'll be posting a reply to your question too. | | Good Luck, keep us informed about how you get on with solving this problem. | | Scott | Many thanks Scott, thanks for the name check. I agree I have not seen this as a problem I would love to see some digital photos of the problem if you care to mail them to me.

If you get a 0.006" stencil and some half decent hole fill during printing I do not see it flying all over the place !!

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Hon Choi

#11616

Re: Pin-to-paste | 7 May, 1999

| | Hi all, | | | | We're starting up tests for pin-to-paste and, well, things could be better. We're testing different pastes and we're testing different apertures rules and, well, we're still testing. It's coming close and we're getting pretty good joint now, but we've got to slow down our chipshooter so that our paste doesn't go flying out every which way. Has anyone been through this phase before? Is there a solution for this or are we the only ones with this problem? | | | | Thank you, | | Hon | | | | ----------------------------------------------------------------- | | | | Hon, | | | | What thickness stencil are you using? If you've got paste flying around the board, it sounds like there's too much paste on there. Pin-to-paste (Intrusive Reflow, Pin-in-hole Reflow, and any other names you can think up for it) is all about striking the right balance between getting good thru-hole joints without compromising the quality of the surface mount stuff. We've gone for a marginal increase in stencil thickness (0.008" instead of 0.006"), increased aperture sizes for the through hole items, reduced apertures for the SMT pads. We're also trying a different squeegee angle (45?instead of 60? to push more paste down into the holes for the thru-hole components. | | | | Bob Willis has done some excellent stuff on Intrusive Reflow. I'm sure he'll be posting a reply to your question too. | | | | Good Luck, keep us informed about how you get on with solving this problem. | | | | Scott | | | Many thanks Scott, thanks for the name check. I agree I have not seen this as a problem I would love to see some digital photos of the problem if you care to mail them to me. | | If you get a 0.006" stencil and some half decent hole fill during printing I do not see it flying all over the place !! | We didn't schedule any tests this week so I don't have any photos for you right now, Bob. However, once we pick up testing again, I'll be sure to send them over for you to take a look at. I'm beginning to think our apertures are too large because our stencil is still only 0.006" thick. I think we'll follow Scott's idea and play with the combination of stencil thickness and aperture sizes. BTW, is 0.008" the norm for this process.

All the best, Hon

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