Temporary connections?

I bet once or twice in the past you wish that you could find a simple way to just hold a module with male headers like this Adafruit GPS module in the pin holes of a circuit board without soldering the pins so you can later take the module and put it elsewhere. Here I found a neat solution, wedging the module with some ESD foam. You get ESD foam pieces from buying ICs so they come for free and have some springy-ness. Then you put in between the module and the board and push in. The force from the foam will make the module form a wedge and there is enough strength to tlit the pins against the holes to make connection. Here are some photos:

The first photo shows the underside of my new phi-3 shield. The GPS module is supposed to be on the top side but unless I solder it to the shield, there is not enough space to make a wedge with the module while it is under the display. So I hang it below the shield board and stuck a piece of ESD foam between the module and the shield board. Here is a side view. You can’t see the foam, which is too dark but you do see the pins are all tilted and thus pushed hard enough to make electrical connection. I only recommend this on a temporary basis. Tomorrow the GPS module is going on another board, the SDI-12 + GPS USB adapter. I’ll solder this time.

Desoldering tricks

Sometimes you need to remove parts from a soldered board. How?

Here is my trick of the trade:

1) Buy some radioshack desoldering wick, suck out the solder from a part. If you can’t remove all solder, take your small screw driver, drive its tip of driver into the wick to make a small puncture hole. Then press the hole against a pin to be desoldered. This makes the wick surround the pin, maximizing area of contact, instead of staying above it or on its side. Then heat the wick around the hole and you will get most of the solder out. I’ve done this quite some times and each time it worked nicely. Next, if you feel you’ve removed all the solder from a pin but it won’t budge, just slightly rock/push it a bit with a flat-head screw driver so the last bit of solder is broken.

Desoldering wick/braid

Desoldering wick trick to remove solder from a pin

2) Some people also opt to destroy the plastic holding the pins together before they proceed to desolder each pin, divide and conquer.

3) You may also buy a radioshack desoldering iron to remove solder by larger amount. I found the desoldering iron very useful at times but as it ages somehow it is unable to remove solder cleanly as before.

Desoldering iron

4) You could also use solder sucker or desoldering tool but I never got hold of a good unit so I can’t say too much but a good one may work nicely.

Desoldering pump/tool

Desoldering bulb



5) If you have a higher-power (de)soldering iron like 30W or more, keep the part in your third hand, try to desolder and when solder melts, quickly use a pair of pliers to pull out the hot pin. This sometimes seals the pin hole so make sure you remove as much solder as you can with some method.

How I soldered header pins for arduino shields

While I was soldering header pins on my Phi-1 shield for arduino, I’ve developed this technique. You can use this technique on most things that have male header pins. You will need two bare PCBs, or you may photocopy your PCB, use double-sided tape to tape the photocopy on a card, poke holes where male headers go. Now use masking tape to hold together the two PCBs or the PCB and the paper copy, sandwiching the male headers in between. Just use some masking take to hold the four corners tightly together. Once you do this, soldering is pretty easy. The pins will be up right, not tilted, or rotated. You can also use an arduino board to hold the pins, then stack the bare PCB on top and tape them together. Since the arduino female headers will conduct heat away, this needs longer time than using two PCBs or PCB and card. I will then use a third hand/holder to hold the board while I solder. If you don’t have a third hand, you can lay the board on a flat surface but sometimes it will wobble when you solder on a corner.

The soldering iron I used for this project was a portable battery-powered dual-setting iron from Weller. I’m experimenting whether this is a good idea. A corded iron has potential for dissaster in a student lab (burns, melting electrical cords and getting zapped). The iron claims to be able to solder up to 150 points. As of now, with the original batteries, I managed to solder about 75 points. I’ve done 60 with a new set of batteries. I’ll solder some more to find out how many more points I can solder with the remaining battery power.

Here’s some pictures:

Male pin headers are sandwiched between two PCBs.

I taped the four corners with masking tape.

Use a 3rd hand to hold the board when you solder.

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