Before I solder very small electronic parts on PCB board, I want to find some needle point sized injector to inject tiny glue fix the parts, then do the soldering. Some manufacturers used that, but I can not find what it is. Can anybody help?

  • \$\begingroup\$ You may think of trying solder paste. It is usually pretty tacky. learn.adafruit.com/smt-manufacturing/solder-paste-syringes \$\endgroup\$ – Steven Goldade Jun 5 '13 at 14:24
  • \$\begingroup\$ You could try a hypodermic needle, I did that many years ago but found as per David's answers it's not really worth the hassle. \$\endgroup\$ – PeterJ Jun 5 '13 at 14:27
  • \$\begingroup\$ thank you all. I used some tiny parts in my circuits, the parts are very tiny and difficult to align them when soldering. I noticed a web site Minicircuits.com has some made devices or call connectors, you can see there is a very tiny solid ball on the PCB, which hold the part. I believe that is a glue ball, but I don't know what the material is and how to inject the ball on to the PCB and part. \$\endgroup\$ – wanwanlulu Jun 5 '13 at 16:07

Honestly, it is more trouble than it's worth if you are hand soldering. I wouldn't bother. It is a lot of work to get the glue and part on properly, and if done improperly it will prevent you from soldering the part correctly.

On the other hand, if you are not using glue and are using a simple hot-air soldering station, then the surface tension of the solder will align the part perfectly for you.

Some manufacturers do use glue, but this is rare and getting more rare. Manufacturers avoid using glue unless they absolutely have to, and glue can't be used on many PCBs. And keep in mind that they are using glue with robots, not with hand soldering.

As for where to buy the glue, or what glue to buy, I really don't know. Nobody uses it by hand, so I don't know if they even make a needle point type injector for use by hand.

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    \$\begingroup\$ And if I remember correctly, the times I've had glued SMT parts was when they manuf. wanted to wave solder those parts at the same time as the PTH parts on the same side of the board. \$\endgroup\$ – placeholder Jun 5 '13 at 14:55
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    \$\begingroup\$ heraeus-contactmaterials.com/en/products/smtadh/… \$\endgroup\$ – JIm Dearden Jun 5 '13 at 16:50
  • \$\begingroup\$ @rawbrawb, also when you need to populate top and bottom SMT and the parts are too heavy to hold with solder surface tension. \$\endgroup\$ – Scott Seidman Jun 5 '13 at 23:29

I wouldn't recommend using glue to fix the components in place before soldering, it could just get messy, and the steady hand you need to apply the glue correctly could just as well be used to solder the component on!

A technique I normally use is to put a bit of solder on the pad first, then hold the component down with a pair of tweezers onto the pad. Then apply the soldering iron to the component - the solder will melt and make the connection to the component.

That's normally enough to hold the component in place and you can solder the rest of the component in. I've done 0805 resistors and capacitors using this method, and SOT-23 packages. Works like a charm

  • \$\begingroup\$ Gluing components to the board is frequently done during PCB assembly mass production. For instance, if you glue SMT components to the PCB, then they can be wave-solder. At the same time, it's not difficult to learn a glue-less technique for manual soldering. \$\endgroup\$ – Nick Alexeev Jun 5 '13 at 16:43
  • \$\begingroup\$ @NickAlexeev For mass production, I assume they don't apply the glue by hand though! That was my logic behind saying don't glue it - not that it's a bad thing to do, I know it's done all the time. It was that if you're glueing it by hand, then you'll need the same amount of care (if not less because of the solder-resist on the board) just to hand solder it \$\endgroup\$ – Matt Taylor Jun 6 '13 at 7:56

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