Reflow test board - Page 1
Forum section: electronics / general

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: December 16, 2020, 01:45:36 am
content: Can anyone suggest a cheap/easy way to test a home-brew reflow oven?What I think I'm after is a board/kit I can run through the oven. I'd like to avoid laying out and manufacturing a custom board for right now (one thing at a time).I see some LED boards on Alibaba, but there are no specifics (part size, test points).I'm sure others have thought about this, and look forward to any recommendations.

author: phil from seattle
author_rank: Super Contributor
timestamp: December 16, 2020, 02:16:38 am
content: Well to get reflow working before you have a board, you either create a test board or find one that meets your needs. For a test board, it should be a pretty quick thing to do as you don't need to route it. Select footprints for the chips you will be using and place them.But frankly, I would design the next project board and use that as a test vehicle. As long as you don't burn the board, you can finish it off by hand. If you have any expensive chips in your design, leave them off until you get the process dialed in.

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: December 17, 2020, 12:25:13 am
content: Thanks for the response. I am looking for such a test board.Using a project board sounds reasonable, but I would prefer to start with a known good design. Having an untrusted board and an untrusted process sounds like trouble. I do not have any experience laying out PCB boards, but would like to learn. I stopped designing/building in the 1990s when things got too small. I'm motivated to try again using reflow.I've been looking through OSH Park for boards, but so far haven't seen anything I like. This is why I'm asking the community for suggestions.Desired features (my wish list):* Cheap. Under $10 for the board and $10 BOM. The idea is to allow for multiple test runs. There are a lot of things to experiment with.* Stand-alone and Testable. Even a blinking LED would be good, such as a 555-based circuit* Known BOM* Stencil availableThere are a lot of boards on OSH Park with no documentation (no BOM, no clue what they might do if functional). There are a lot of very expensive boards, which I feel are not suitable for learning. I found a 555 blinker board for $5, but it is through hole. No documentation, just a board.There are SMD solder practice kits, which sound promising. But none seem to have stencil availability. I am not interested in learning to hand solder parts.

author: phil from seattle
author_rank: Super Contributor
timestamp: December 17, 2020, 01:24:55 am
content: Yeah, the OSHPark shared projects are not curated. There isn't even a mechanism for feedback on a given project. A lost opportunity for Lian. I use them for sharing small projects that I would place squarely in the "convenience" category.But, TBH, a board big enough to be a good test for your oven is likely to be too expensive - generally my size limit for using OSHPark is 4 inches square.And, I think your standards for a test board are a bit high. It doesn't need to be a functional board as you can inspect solder joints with a little magnification and buzz them out with a continuity tester. I'd mix a bunch of different parts - soics, tssops, sots, 603s, 805s, maybe 402? Include a lot of test points to make buzzing the connections out.

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: December 18, 2020, 12:29:48 am
content: Good point on function. Between visual inspection and connectivity checks, that should be enough. I have a small concern with stencil thickness using different part sizes. I don't know the tolerance for solder thickness. Maybe I can find some middle ground.I had hoped to avoid laying out a board, but in this case it would be no problem. I don't have to worry about design rules or any such stuff. Just pads for soldering parts, and traces to larger test points to ring out.A single large board would be too expensive. But several small, cheap boards would work. Think one small board in the center, one in each corner.A thermocouple attached to a board in each position should give an accurate temperature profile at each spot.I'm overthinking this a bit, because I want to be able to trust the oven to perform. Also it is kind of a fun problem to consider.

author: Fred27
author_rank: Unknown
timestamp: December 18, 2020, 10:11:39 am
content: Surely you must have some spare PCBs from previous projects? It would be unusual to build a reflow oven before spinning up your first board.