Best Practices for Aligning and Soldering TH connectors - Page 1
Forum section: electronics / projects

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 05, 2014, 09:00:04 pm
content: Hello, I have a new design that uses a fairly inexpensive yet rugged connector that is the quick-connect tabs found on appliances and industrial controllers. On many PCBs I have seen them riveted or staked presumably prior to soldering, but this style cannot be used in such a manner.What is an example of a fixture design that might be used to hold them in alignment without tipping or twisting?http://www.keyelco.com/product.cfm/product_id/605

author: mjrandle
author_rank: Contributor
timestamp: December 05, 2014, 09:24:39 pm
content: You haven't mentioned volume or number of terminals. But I would machine slots (with some clearance) in a block of plastic to match depth / length of terminal then have a comb arrangement to pull the terminal against side of slot. 3D printing can be useful for this style of fixture because it can create features which are impractical or impossible to machine.Cheers,Mike

author: w2aew
author_rank: Super Contributor
timestamp: December 05, 2014, 09:38:29 pm
content: Quote from: envisionelec on December 05, 2014, 09:00:04 pmIf you don't need to do too many of them - then holding them in place with some kapton tape would work well. Is the base metal ferrous? Try holding them in place with a flat magnet. A little more robust, try cutting some slots in a blank piece of PCB material. 3D printed plastic would probably melt during soldering. For larger volumes, you could machine some good high-temperature plastic or composite material.

author: Yago
author_rank: Frequent Contributor
timestamp: December 05, 2014, 09:52:55 pm
content: Make a jig that holds the female of the connector in place. (wood is easy to work with for this)Slot on the males, solder and Bob's yer' aunties live-in-lover.

author: ajb
author_rank: Super Contributor
timestamp: December 05, 2014, 10:04:41 pm
content: Keystone has what they call 'Sturdi-mount' variations of many of their QC terminals--not sure if they have one for the exact one you're using, but they have little protrusions on the side that help prevent side-to-side bending and help align the terminal to the board. You may or may not find them helpful, from memory I don't think there's much cost difference.When I've done prototypes with similar terminals I sometimes find it easier to solder them from the top. That way you can easily see how the terminal's aligned as you're soldering (and adjust with a pair of tweezers if necessary) and with the way the thermal mass is distributed I find it easier to get a nice top and bottom fillet.

author: lewis
author_rank: Frequent Contributor
timestamp: December 05, 2014, 11:01:43 pm
content: We made 1000 of a product that used 12 of the vertical version of these terminals each. I made the holes in the PCB slightly too small so they would press-fit in the board without falling out or jiggling about when the board was turned over to solder. I made a crimp tool and employed someone to crimp in 12000 terminals by hand. Damn glad I wasn't doing it.Worked rather well, but I would never ever do it again! Next time I'll make a plastic jig that will keep the pins in straight, and put the board through a wave soldering process. It's a lot easier to rely on gravity to hold the parts in.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 06, 2014, 01:30:06 am
content: Uh, make sure the jig is something relatively refractory (phenolic, teflon, whatever that liquid crystal stuff they make molded connectors out of, etc.), needless to say, not something you're going to 3D print yourself. Those terminals are usually tin plated brass, so they are quite conductive. Expect the whole part to reach soldering temperature. Getting stuck to a half-melted jig would be...unproductive.Offhand, I don't know how they prefer to do those. Call up an assembler and ask?Tim

author: SL4P
author_rank: Super Contributor
timestamp: December 06, 2014, 11:17:41 am
content: Quote from: Yago on December 05, 2014, 09:52:55 pm+1 this is easy, fast and cheap.Use a female - with the plastic removed - as a guide mounted to the wood/whatever.any blue/yellow mounting goop will hold the jig in place while you turn over and solder.

author: kb0thn
author_rank: Contributor
timestamp: December 07, 2014, 02:03:01 am
content: I have used that style of connector on a few boards. We haven't built thousands, but we have built hundreds.Just hold it with your fingers and tack solder one leg. Then fully solder the other leg. Then go back and fully solder the first leg.If you are just doing a few, push on an insulated female terminal and then you can hold it with your fingers and not worry about getting burned.-Jim

author: pickle9000
author_rank: Super Contributor
timestamp: December 07, 2014, 04:05:21 am
content: - Best - Set the footprint pcb holes close enough together to get a friction fit.- Next best - Make a simple holder jig using the mating connectors mounted/soldered to a small strip of brass. For this to work you will probably need to loosen the pinch points a bit. The easiest way to make this type of jig is to hand solder a perfect set. Mount on the mating connectors then solder those to the brass strip. To use install the connectors in the holder and then on the pcb. You will find that they tend to stay in place, if not bow the brass slightly and they will.

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 08, 2014, 01:29:02 pm
content: Great! Thanks everyone for your excellent feedback.I think I will go with a machined PTFE jig that has spring metal to pinch the connector in place and a backstop to align it. The PCB is loaded and the jig is placed on top. It will be designed to self-align with the connector pitch and a single peg will align to the PCB, preventing twist.Yep, these will first be made by myself with the intent to be mass produced.