Chances of a successful desoldering (at home) - Page 1
Forum section: electronics / general

author: Illusionist
author_rank: Regular Contributor
timestamp: May 18, 2019, 09:19:16 pm
content: I have myself a NEO-M8T module to make a GPSDO, but I need a board to put it on. I thought of buying a Chinese GPS board and removing the module on that, to reuse the board. The pinouts are the same.The first attempt didn't go well for either the module (not bothered) or the PCB, which ended up with practically no pads left on it. That was with a Weller pencil iron, binocular microscope and ChipQuik. I guess either my kit or my skills just aren't up to removing it that way. I think my ChipQuik is leaded though, and the board wasn't.I'm thinking of trying another by simply heating the whole board on a hot plate and picking off the module. However, the first module was also stuck down to the PCB (which also probably played a hand in its destruction) so I'm not sure if heating it up is going to do the trick. Or if it's even a good idea anyway.Suggestions are most welcome!A picture of the board is attached.

author: Illusionist
author_rank: Regular Contributor
timestamp: May 18, 2019, 09:55:14 pm
content: It was definitely stuck down. I can't tell if it's a very thin layer of adhesive or thin double-sided tape. The residue on both module and PCB is sticky. Probably heating it up to 200C is going to soften it though.I have an Antex gas soldering iron that has a hot air tip. No temperature control, but it's worth a go. I'll try it the way you suggest with a preheat. Just as soon as I improvise or round up a hot plate... (thinking stainless frying pan on the gas stove).

author: NorthGuy
author_rank: Super Contributor
timestamp: May 18, 2019, 10:08:57 pm
content: This is not much of a board. You can make your own boards, for example on PCBWay.com

author: Illusionist
author_rank: Regular Contributor
timestamp: May 18, 2019, 10:45:28 pm
content: Yes, there is that option. I've never had a board made though, and it's been many years since I designed one (and only as an amateur). Since I'm getting back into electronics after a decade's hiatus I have a lot to relearn.I've already destroyed more than the PCB would have cost me. This last board has a fake module on it, so no loss if it doesn't go well and I'll install Eagle and start learning again.

author: Psi
author_rank: Super Contributor
timestamp: May 19, 2019, 02:04:36 am
content: Sometimes the flux residue underneath can seem like adhesive because it is sticky and can hold down the sub board harder than you expect when over a large surface area.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2019, 02:13:39 am
content: Forget Eagle, it has gone subscription-only. The hobbyist community has been jumping ship for KiCad which is completely free and open source. This looks like a very simple board.

author: OwO
author_rank: Super Contributor
timestamp: May 19, 2019, 07:38:25 am
content: Yes, I have designed everything from Zynq + DDR3 boards to RF power amplifiers with gEDA, and I'm sure kicad is more full featured. There is almost no need for commercial PCB software in this day and age.

author: Illusionist
author_rank: Regular Contributor
timestamp: May 19, 2019, 11:43:31 am
content: Quote from: Psi on May 19, 2019, 02:04:36 amYes, that could well be it instead of an adhesive. It makes more sense.As to EDA software... I came across KiCad last night and installed it. I'll have a go at designing the PCB. I used Altium and a few other big names years ago, and Orcad at university, but never enough to get locked into their methodologies.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2019, 05:42:53 pm
content: There are a bunch of tutorial videos out there, watch a few of those and it shouldn't take you too long to get the hang of it.

author: Spragnut
author_rank: Contributor
timestamp: May 19, 2019, 09:08:50 pm
content: I had real trouble getting a similar packaged module off a board. I'm pretty proficient at soldering but this just wasn't playing ball. I think because the thermal mass of it was quite high, I don't have a particularly great hot air rework station.Ended up using ChipQuik. Really low melting point solder. Was a doddle when using that.Sent from my SM-G975F using Tapatalk

author: Illusionist
author_rank: Regular Contributor
timestamp: May 20, 2019, 08:38:31 am
content: I thought chipquik would do the job but mine didn't. It seemed to turn the solder into a plasticine-like consistency that I could push around with the tip of the iron, but it still resisted melting.Afterwards I realised that my chipquik is really old and will be for leaded solder. I guess there's quite a difference.

author: tautech
author_rank: Super Contributor
timestamp: May 20, 2019, 09:14:28 am
content: When you think you're dealing with lead free muck and it's pretty easy to recognize it with a little experience, flood the joints with a leaded solder to dilute the lead free muck and suck it off with a sucker or braid and have another go with what should be a lower melting joint the second time around.Tricky ones sometimes need a rinse and repeat.BTW, if you're gunna use that Antex gas gun do some practice on an old PCB first.A paint stripper gun with a small tip will be easier to manage than a flame.