16 ms·
NASA's Through-Hole Workmanship Req (2002)
- heyflyguy 6y agoEvery now and again this pops up on a different forum. I wonder how much is actually hand soldered any more vs. pick and place machines with SMT.
- Pasorrijer 6y agoIn critical applications, much more than you'd imagine. Lots of defence and critical component suppliers still maintain a significant amount of hand work for low volume and critical areas. Don't have a source unfortunately other than personal experience working as an engineer.
- lmilcin 6y agoOver the years I have seen couple of closeups of various boards on youtube. As electronics is my hobby, I tend to pay attention to this. They all looked hand soldered to me. And the soldering job always looked very, very high quality.
- audiometry 6y agoI've been told that in areas where lots of prototyping isgoing on, there is lots of scope for manual rework. (a pcb design only 95% correct needs modifications to figure out the right design)
- phkahler 6y agoWe had a board where somehow the footprint of an 8 pin SOIC got flipped in the layout. One engineer was able to desolder it, flip it, and solder it on using wires so that it floated about 1-2 cm above the board upside down. I was impressed ;-)
- garaetjjte 6y agoSo-called "dead bug" method.
- HeyLaughingBoy 6y agoFor low volume, it can cost more to set up the P&P machine, deal with alignments, check first articles, etc. than just soldering a few (dozen) board by hand. And there are a lot of small companies in niche markets whose annual production of a PC board might be in the single digits. That and, people who hand solder stuff all day are fast.
- antoniuschan99 6y agoSome fab I checked out use manual pick and place if the quantity of boards is less than 100 since it probably takes more time to set up the automated stuff at such low volumes. I’ve see the videos on IG every now and then on their hand soldering skills. So fast!
- konschubert 6y agoI knew I was bad at soldering, I didn't know I was THAT bad. I need to take a course.
- cushychicken 6y agoKeep in mind: this stuff has to be as close to perfect as possible because lives depend on it. Unless you're sending your stuff to space, I suspect you can cut yourself a bit of slack here. :)
- konschubert 6y agoThe fact that my components keep failing says otherwise. ;)
- EarthIsHome 6y ago"The bigger the blob, the better the job."
- mordechai9000 6y agoSome of my work looks like I was trying to use solder as a conformal coating.
- NDizzle 6y agoYeah. Damn. I hope nobody at NASA looks at some of the repairs I've had to make on my riding mower. I blame the work angles of some of those jobs...
- alextheparrot 6y agoIf it makes you feel any better, I burned my hand pretty bad when mowing the lawn as a kid when my dad’s exhaust pipe repair fell off. No harm, no foul is what I mean to say, haha.
- NDizzle 6y ago
- jcims 6y agoWas curious what their treatment was going to be regarding tin whiskers. Not much there (of course this is point in time inspection so it kind of makes sense), but a quick google revealed quite a bit of study: https://nepp.nasa.gov/whisker/ https://nepp.nasa.gov/whisker/ I thought they were just one of those low probability items until a Sunday morning when I was running live audio for a church service. Singer was mid verse and BOOOOM! Huge booming sound over speakers startling everyone into nervous laughter. I opened the cable up afterwards and sure enough found these alien crystalline structures growing between the conductors. It had shorted and even the little bit of current in the microphone vaporized about a mm of material. Really really weird and I'm certain kept some folks up at night over the years.
- gte525u 6y agoNASA and aviation in general are later adopters of lead-free. It definitely wouldn't have been reflected in older standards.
- segfaultbuserr 6y agoAFAIK, lead-free soldering is never enforced in space applications. An exemption is granted because of its extremely high reliability requirements.
- mauvehaus 6y agoOn several levels. Avgas is still leaded.
- octoberfranklin 6y agoWow, that's disgusting.
- scrumper 6y agoIt's pretty limited. Avgas doesn't mean jet fuel, as used by commercial aviation, it means the stuff you pump into piston engine light aircraft. Plus, at the risk of being obvious, the exhaust is either emitted way up in the air or, if at ground level, out in the middle of nowhere at an airport.
- shireboy 6y agoAnybody have tips on how to get to this level of solder-fu?
- tsomctl 6y agoFlux, practice, flux, good tools, flux, good lighting, flux. Really, learning how to braze and weld steel helped me a lot. Heat control is extremely important. Heat flows, and you learn how to position your iron to get the heat where you need it. You can also tell how hot something is by how the puddle looks.
- inamberclad 6y agoHeat control. Cleanliness. High quality tools and solder.
- buescher 6y agoTemperature control is so inexpensive these days you should not bother with heat control. Unless by heat control you mean the right size tip for the job, in which case we agree.
- inamberclad 6y agoI meant in a more general sense, both temperature and heat flux.
- buescher 6y agoNot for you, but for those that might not get the point: the world of electronics assembly is really strange - it's like the whole past is present with us. It's 2021 and you can still buy a Weller soldering station with a knob for open-loop power (= heat) control for more than you'll pay for a cheapish station with closed-loop temperature control from any number of Chinese brands. (google "Hakko 936 clone"), Closed-loop temperature control is much superior to open-loop power control.
- DanBC 6y ago
- fallingfrog 6y agoThese are all good rules. Sometimes it can be really hard to tell when a solder is solid. You can get hairline cracks that aren’t visible to the naked eye but cause intermittent problems.
- js2 6y agoWire splicing: https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/407%20Splices.html https://workmanship.nasa.gov/lib/insp/2%20books/links/sectio...
- audiometry 6y agoThese high standards aren't unique to NASA. These few days I've been taking a micro-soldering course taught by Hakko. They are teaching standards IEC61191/JISC61191 (Japan Welding Society standard) and a lot of details are similar.
- buescher 6y agoThe NASA handbooks are good. I like the one for rework that shows neatly staked wires. There are a couple of subtleties you could miss on this one though: 1) On page three, that exposed end of the lead is a defect if you're NOT going to conformally coat the board. If you don't know what a conformal coating is, it's a defect. 2) On page eleven, flux residue. Sure, for NASA's applications. For most commercial applications, the IPC rule is "excessive flux residue". For prototypes, one-offs, and hobby projects, my rule of thumb is, if you can't measure the difference removing flux makes, leave it there. Incompletely cleaned flux can be more corrosive than undisturbed flux. Also, no-clean flux should be called "never clean" flux. Never clean it with ordinary methods because you will never get it clean.
- lmilcin 6y agoI dislike no-clean. I like my boards pristine with nice, shining leaded solder and no residues.
- buescher 6y agoThat's fine, I like them that way too! But as a hobbyist, you risk leaving corrosive salts on the board or worse, sloshing them into electromechanical parts like switches, pots, unsealed relays, sounders, etc. Getting to "pristine" is harder than a lot of people think. There's a vicious cycle in production where assemblers will use too much flux, get flagged in an IPC-610 evaluation, try to clean the boards, and then get flagged for high ionic contamination in the next evaluation. You can't see the salts you leave behind from incomplete cleaning. Beginners should not ever clean flux. Most hobbyists should never need to clean flux. Professionals should have data driving any decision to clean flux.
- lmilcin 6y agoFortunately, I rarely risk anything if the board fails. And if it does I always try to understand what caused the failure. I never considered flux compatibility between my solder rosin core and the flux paste and never considered measuring salt residues on the board. I almost exclusively use the same Kester sn64pb37 rosin core solder and MG Chemicals #8342 RA rosin flux paste. Both must be cleaned promptly. Now, I don't bother cleaning if I don't intend to use the board after I test it (like when I do prototyping) but anything else gets a thorough wash. I use various PCB cleaners, typically ethanol (not IPA!) based and then rinse boards in electronic water. I never saw any oxidation on any of the traces unless there was some external contamination.
- environment 6y agoHere is the link to the rest of those workmanship standards: https://workmanship.nasa.gov/lib/insp/2%20books/frameset.html https://workmanship.nasa.gov/lib/insp/2%20books/frameset.htm... There is also more if you search for NASA-STD-8739.3.pdf I want to share some of my thought on soldering: The best way to understand soldering is to think primarily in terms of surface tension or capillary action and intermetallic compounds. You set it up correctly and apply heat so that fluid dynamics can finish the job. The atoms get to where they are supposed to be. There is no technique or dexterity required with the soldering iron itself. I would also recommend that you think of solder wire as a 2in1. The flux core in the solder wire is helpful, but not the endgame. Use extra flux from a flux pen or flux bottle that is compatible with the flux core in the solder wire. For example: You can put a glob of solder on the tip of your soldering iron and just bring it in to the surface or joint. If you have pre-applied flux on a clean surface or joint, the liquid solder will wick off the soldering iron and onto the surface by itself. Perfect every time. (Surface tension, capillary action.) For manual hand soldering, the flux management is the only complicated part. What flux to use? Do you have to clean it? How to clean it? Saponifiers, or IPA good enough? Compatible with the flux in the solder wire? You must be sure to reach the activation temperature of all the flux on the board or it can corrode metals over time. "No Clean" fluxes are really hard to clean without special saponifiers, I would avoid these fluxes. Is the flux residue on the board still inert after it gets wet by accident or at high humidity? There are also problems with high frequency circuits and No Cleans. Water soluble fluxes require excellent process control. Even tiny defects in the PCB can cause failures if you use water soluble flux. Read the datasheets and recommendations from the flux manufacturer. Some fluxes are more easy going: For you Americans I would recommend Kester 186 Flux-Pen and Kester 285 Sn63Pb37 RMA Flux-Cored Wire. Do not use more flux than necessary, do not make a mess. Use eye protection for this flux from Kester! Soldering gets even more interesting with gold embrittlement (gold plating thickness and migration to the center of the IMC), tin whiskers, silver whiskers, etc. There is much more to all of this if you want really high reliability. I went deep down this rabbit hole once. Not a professional soldering guy. Just obsessive compulsive about high reliability design. This is enough text for a post on HN :)