![]() Also, overprinting strategies will be different for tin/lead and lead free solders as well as no-clean or aqueous pastes. Sometimes, you can get lucky and just make your aperture 10% larger than your annular ring of the hole, but depending on the pin to hole ratio, you may need to overprint. Not real common, but they are out there.ĥ) Determine proper aperture size for your stencil. Some reflow compatible parts will give different hole size recommendations as compared to their wave solder counterparts. I would bet he would be successful if he played with his profile settings while monitoring thermocouple attached to a pin on the left header connected to the ground plane.Ĥ) Ensure you are using the proper hole size. Essentially, the performance of the profile he used is too reliant on the board sitting on the plate. This can be seen at 14:20 where the left side of the board with the larger thermal mass (aka copper ground plane) did not reach proper TAL (Time Above Liquidus). The one the Clough42 used is perfectly capable as seen on the right hand side of the board, but his profile was incorrect for the thermal mass imbalance that exists with his board. A plain toaster oven will be a stretch if your design and the part being used do not allow for some tolerances during reflow. A few parameters related to intrusive reflow may need to be carefully controlled. Also, component mass is to be considered for double sided boards where the TH part will be on the first side ran.ģ) Know your oven’s capabilities and how to set your profile correctly. Reflow compatible parts will be deemed as such as well as max temperatures, plastic material, etc. Phil Zarrow of ITM Consulting released an article in the Journal of SMT in October 1999 that mentions a couple internal Motorola documents.Ģ) Read component datasheets. It is not a new process by any means yet dates to 1986 when Robert Clawson of Motorola ran experiments and then released an internal document entitled “Factors Affecting Reflow of Through Hole Mount Components” in 1987. Maybe “lessons learned from a first run experiment” is a better title with a less insulting connotation.ġ) Fun facts: The process is called several names: Intrusive Reflow, Intrusive Solder, Pin In Paste, Paste In Hole, Reflow of Through Hole (ROT), or the very old term “SCRS”, Single Center Reflow Soldering. However, I don’t think calling this video “Fail of the Week” is appropriate. Posted in hardware Tagged fail of the week, flux, header, reflow, smd, smt, soldering, through hole Post navigationĪs someone who routinely reflows TH components at a low-to-mid volume, high-mix contract manufacturer, I have some comments for others looking to take advantage of this process as there are some valuable benefits. And we highly recommend the electronic leadscrew playlist to anyone interested in the convergence of machine tools and electronics. Hats off to for trying to save his future customers a few steps on assembly, but it’s pretty clear there are no good shortcuts here. He blames poor heat conduction due to the lack of contact between the board and the reflow oven plate, and we agree perhaps an aluminum block milled to fit snugly between the header sockets would help. ![]() The female header socket and the power jack fared better, so he tried reflowing them, but it didn’t work out too well, at least for the headers. The Phoenix-style connectors discolored and changed dimensionally after a trip through the oven, and the plastic on the pin headers loosened its grip on the pins. ’ thought was to run the boards back through his reflow oven to add the connectors, so he tried a few experiments first on the non-reflow rated connectors. The PCBs were partially assembled by the board vendor, leaving off a couple of through-hole connectors and the power jack. We covered the proof-of-concept for the project he’s come a long way since then and is almost ready to start offering the ELS for sale. The boards are part of his electronic lead screw project, an accessory for lathes that makes threading operations easier and more flexible. ran into this problem recently, and he tried to solve it by reflowing through-hole connectors onto assembled SMT boards. It’s not without problems, though, particularly when you have no choice but to include through-hole components on your SMT boards. It means easier automated component placement and soldering, and it’s a big reason why electronics have gotten so cheap. There’s no question that surface-mount technology has been a game-changer for PCB design.
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