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enter image description hereAt our company, we are manufacturing a PCBA with a thickness of 0.8mm. After applying solder paste at the pad position of the through hole, we attach the PTH component before transferring it to the reflow oven.

It seems that the position still lacks solder, we have to touch-up manually to fill this position.

Do you have a solution for this problem?


For sure, we've been using hand soldering after the SMT process, but that's also what I wanted to improve the process, I learned the paste-in-hole method. Does it work, please give me advice.

I am planning to change the sweeper angle from 45° to 60°.They say it will have more solder in the hole but will also be more dangerous for the stencil and PCB.

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  • \$\begingroup\$ We very rarely use the wave furnace to weld this position (because of low output and small number of solder points). \$\endgroup\$ Oct 18, 2022 at 5:58
  • \$\begingroup\$ I see it's just a fixed pin not a function pin, but according to the standard i still need to fill the bottom surface of it \$\endgroup\$ Oct 18, 2022 at 6:59
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    \$\begingroup\$ Those are huge holes that need to be filled. Even if you fill the entrire hole with solder paste it probably won't be enough solder to give you a solder joint that's to spec. No Idea how to solve that without reverting to wave soldering or hand soldering, sorry. Or a design change to a SMT connector \$\endgroup\$
    – kruemi
    Oct 18, 2022 at 7:09
  • \$\begingroup\$ What you are experiencing is not unusual. On PCBAs with big leaded parts or heavy copper, it is common practice to have to do a manual solder operation in areas. We plan for it in the production flow. \$\endgroup\$
    – SteveSh
    Oct 18, 2022 at 11:32
  • \$\begingroup\$ @JonathanChuUHAN - Hi, You wrote an "answer" but it wasn't the answer to your original question. It was additional information, so it has been added to your question as an edit (i.e. an update) instead. || Unless you are writing the full and final answer to your own question (i.e. unless you have solved the problem yourself and don't need further help) please don't use the box labeled "Your Answer" below. Instead, please edit the question to add new information & clarifications. Or write a comment if you are responding to one answer. Please see the tour and help center for more rules. Thanks. \$\endgroup\$
    – SamGibson
    Oct 19, 2022 at 7:52

2 Answers 2

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Sometimes some components are hand soldered at the factory after the SMT components go through reflow.

So solder the components manually.

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To deliver enough solder paste to solder a through-hole component requires some special handling with the stencil (such as overprinting) and with design. Check out design guides from PCBA houses.

I would most certainly use drilled slots for those particular leads rather than huge gaping through holes. They're not going to be all that strong even when hand soldered with a ton of solder.

For what you have, without changing the PCB design, probably manual touch-up is the way to go until you do another PCB turn.

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  • \$\begingroup\$ What's a drilled slot? \$\endgroup\$
    – DKNguyen
    Oct 19, 2022 at 3:56
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    \$\begingroup\$ @DKNguyen a slot created by drilling a series of overlapping holes next to each other. It just looks like a slot when plated. Usually a standard thing with no additional cost these days. \$\endgroup\$ Oct 19, 2022 at 7:19

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