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I am small scale manufacturing PCB's I designed for high power actuator and LED control. It is 6"x8", 2 ounce copper and large power and ground planes, with no thermal reliefs. It has a section at one edge that is all SMD components, a large copper through hole buss bar that spans the entire length, and several through hole MOSFETs, and several through hole connectors.

So I have make 10 boards so far, and will be making around 5 a week. I use a hot plate for the SMDs, and that works great.

For the TH components, I use a hot air reflow gun, and use a soldering iron. This is not ideal. I have to put a lot of heat on it, and I struggle with cold solder joints if I don't get enough heat on it.

So, I am content with my method for the SMDs, as with a solder stencil, I am able to solder them quickly and quite consistent. For the TH components, I need a new method. I have a few options I've considered:

  1. Use a IR preheater that goes under the board to heat the planes.

  2. Same as 1, but with a forced air convection heater.

  3. Get a larger spread nozzle for my hot air gun, and an articulating arm that can hold it to help heat more evenly.

Budget is whatever it takes, but I would like to stay under $1000 if possible. Let me know what you think, and if there are options I'm forgetting.

EDIT: I want to do this as correctly as can be done without large scale procedures, these are high power expensive boards, and don't want to take risks with how I heat it, like I feel like I may be doing now.

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  • \$\begingroup\$ Have you tried a higher-power soldering iron? Use it to pre-tin the area you'll need to solder, let cool, then you can make the final solder joint without applying as much total heat, since all you have to do is melt the outer solder layer. \$\endgroup\$ – WhatRoughBeast Aug 24 '18 at 13:07
  • \$\begingroup\$ For a future model, could it be designed with a daughter board for the SMD components, so that you could more freely use different assembly techniques for each board? Although I don't see wave soldering machines for sale on ebay. \$\endgroup\$ – Andrew Morton Aug 24 '18 at 13:20
  • \$\begingroup\$ @AndrewMorton I could have, but yeah I would still have to figure out what to do with the through hole components. \$\endgroup\$ – Kyle Hunter Aug 24 '18 at 13:55
  • \$\begingroup\$ @WhatRoughBeast would it be powerful enough? And that would be less thermal shock then what I'm doing? \$\endgroup\$ – Kyle Hunter Aug 24 '18 at 13:55
  • \$\begingroup\$ @KyleHunter - I have no idea. Try an iron with twice the power of the one you're currently using. \$\endgroup\$ – WhatRoughBeast Aug 24 '18 at 17:29
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So I decided to go with what @WhatRoughBeast suggested. I purchased a Hakko FX-801, with a few of their large heat capacity tips for around $1100 total. It has a power output of 300 watts.

I have assembled 5 boards with it, and it is truly incredible. It can heat up any component including my large heat sinks and buss-bar to soldering temperature within 5 seconds.

Highly recommend this iron to anyone in a similar situation

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