Previously I’ve bought some pin headers and soldered with them, but with my bad novice soldering skills, I’ve had trouble with the insulation material melting. On male pin headers in particular, this would be problematic because then the pins would sag over and ruin the usability when the pins would be sticking out at the wrong angle. On the other hand, I had some female sockets that I charred a number of times, but they didn’t end up so bad from my extra soldering ironing heating.
So, what can I do in the future when buying new pin headers to get more temperature-resistant ones? Avoid plain Polybutylene_terephthalate (PBT) headers. Glass-fibre reinforced ones, however, are more temperature resistant. Polyester headers are also more temperature resistant, and weird-sounding materials like liquid-crystal polymer (LCP) and polycyclohexylenedimethylene terephthalate (PCT) are pretty temperature resistant. The higher temperature ones can be placed in a reflow soldering oven, while plain PBT may be unsuitable for such treatment.
Please also see my hot temperatures article for reference.
20200311/https://en.wikipedia.org/wiki/Polybutylene_terephthalate
20200311/https://en.wikipedia.org/wiki/Polyethylene_terephthalate
20200311/https://en.wikipedia.org/wiki/Polyamide
20200311/https://en.wikipedia.org/wiki/Nylon_6
20200311/https://en.wikipedia.org/wiki/Nylon_66
20200311/https://en.wikipedia.org/wiki/Liquid-crystal_polymer
20200311/https://en.wikipedia.org/wiki/Polycyclohexylenedimethylene_terephthalate
UPDATE 2020-03-16: Although Nylon can withstand higher temperatures, it is not suitable for reflow soldering due to its high moisture absorption rate. This means its dimensional accuracy is highly dependent on the environmental moisture and temperature level.
20200316/DuckDuckGo nylon reflow soldering
20200316/https://sullinscorp.com/wp-content/uploads/2015/04/Nylon-6t-and-Reflow-Soldering.pdf
20200316/DuckDuckGo nylon moisture absorption rate
20200316/https://www.toray.jp/plastics/en/amilan/technical/tec_003.html
Likewise, according to this source, glass-filled polyester is also not suitable for reflow soldering. The stated plastics that work well with reflow soldering are “Liquid Crystal Polymers (LCP), Polyphenylene Sulfides (PPS) and Polycyclohexylene Terephthalates (PCT).”
20200316/DuckDuckGo glass filled polyester reflow soldering
20200316/http://suddendocs.samtec.com/processing/smthb/plastics.html
Noteworthy is that Nylon does not have as high a heat deflection temperature as polyethylene terephthalate.
20200316/https://en.wikipedia.org/wiki/Heat_deflection_temperature
20200316/DuckDuckGo nylon heat deflection temperature
20200316/https://www.creativemechanisms.com/blog/3d-printing-injection-molding-cnc-nylon-plastic-pa
Merely discussing temperature resistant plastics, I am somewhat missing the point of why you need temperature resistant plastics, the implications of those choices, and how people were able to get by without temperature resistant plastics. So, I will be more punctual in that explanation here.
Reflow soldering requires that you have your entire board subject to high temperatures. This means that every single component on your board must be capable of tolerating the temperature range of reflow soldering, typically 220 to 260 degrees Celsius. Your main point of concern is plastic since most plastics melt below the reflow soldering temperature. “Plastic” IC packages are in fact made of high-temperature epoxy and are therefore safe for reflow soldering.
This is why selection of pin headers on circuit boards can be problematic. Often times, the insulation material is some sort of fairly typical plastic, which can’t tolerate reflow soldering temperatures. Only specially formulated plastics can tolerate reflow soldering temperatures. Of course, this doesn’t come without a price.
So, how did people ever get these low temperature plastics onto boards in a commercial mass manufacturing process? They used wave soldering. Wave soldering, unfortunately, pretty much requires that you only use a single-sided circuit board since a wave of molten solder must pass over one surface of your circuit board in its entirety. But, its advantage over reflow soldering is that the board as a whole can be subject to lower temperatures so that your plastics will not melt.
Finally, for small prototyping or custom manufacturing runs, hand-soldering with a soldering iron is also a viable method to avoid subjecting plastics to temperatures above their melting point… provided that you are reasonably skilled with using a soldering iron.
What does DNP mean in a schematic? DNP = Do Not Place. It is used to indicate an empty footprint on a board where components can be placed ad-hoc by the end user after the standard assembly process.
20200311/DuckDuckGo resistor DNP
20200311/https://electronics.stackexchange.com/questions/255555/dnp-means-to-short-or-keep-circuit-line-open