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Background: I'm watching many SMD soldering tutorials these days, but I'm still not ready (too nervous!) to actually try it with my PCB and DAC TI PCM5122PW:

Question: Can I put the SMD chip on the PCB and hold them together with Scotch tape during a few hours, and power on my PCB, to test it everything is working ? Will the SMD chip's pins be in contact with the PCB pads, if just held with Scotch tape?

Note: I'm not asking about using adhesive tape to hold the SMD chip for soldering purposes, but really for having, during a few-hours, real contacts between PCB and SMD chip.

Basj
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  • I wouldn't trust that contact, but I think it would likely work to some degree. Definitely don't rely on it to tell if your circuit will work or not, though. – Hearth Apr 26 '17 at 00:54
  • Also, I have no idea if scotch tape is conductive or not. If it is, it might mess things up. – Hearth Apr 26 '17 at 00:56
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    The risk of ESD damage is very real. Don't do it. – Matt Young Apr 26 '17 at 00:58
  • Oh, good point. Didn't even think of that! – Hearth Apr 26 '17 at 01:04
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    Learning to solder will probably be less frustrating than dealing with sketchy connections. – Wesley Lee Apr 26 '17 at 01:16
  • Soldering this isn't hard. However, if you think you want to remove it, you need a hot air tool, or to risk taking a lot off with a larger heat gun, or damaging the board in an oven. Taking an IC off with solder braid is very tedious - if you have to do it, feed a fine steel wire under the pins to raise them. But do that even just once, and you'll be ordering a cheap hot air tool! – Chris Stratton Apr 26 '17 at 01:32
  • @ChrisStratton How much is a cheap hot air tool? – Basj Apr 26 '17 at 18:45
  • Looks like around $40-50 for a basic fan-in-handpiece temperature controlled station. You may see some lower prices but factor in shipping cost/time too. – Chris Stratton Apr 26 '17 at 18:52

2 Answers2

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3M "Z-Axis" tape would be a better choice. It is placed between the part and the board, and is conductive through the tape but insulative along the tape.

Ignacio Vazquez-Abrams
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  • Now that's really handy. Adhesive zebra strips, in tape form. Might have to get myself some of that! – Hearth Apr 26 '17 at 01:09
  • Oh really, [such kind of tape](https://www.adafruit.com/product/1656) would work for a small SMD chip like this DAC TI PCM5122PW? How would you estimate the chance of having all contacts working? It looks amazing! – Basj Apr 26 '17 at 01:12
  • @Basj: The datasheet recommends 0.4mm spacing minimum, and Sparkfun has a video of a SMD ATmega328P working using it floating around somewhere. – Ignacio Vazquez-Abrams Apr 26 '17 at 01:24
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Yes, technically you can, but it is not a good idea for many reasons, the main ones being that the contact is unreliable (which might lead you to believe that there is a problem with the components), if the board gets shifted while in use, the dramatic and repetitive changes in contact reliability could potentially damage the component, and if something shifts so that it is connecting the wrong pins, that could be bad for the circuit.

In short, yes you can, but it's not a great idea.

The Elemental of Destruction
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  • Thanks. Is there another solution, that allows me to test, before doing a permanent real SMD soldering (I'm not ready! Too scared about doing a bad soldering right now!) – Basj Apr 26 '17 at 01:03
  • More accurately, you can *try* but this is extremely unlikely to actually work with just tape over the top. Special Z-axis tape might do it, or something that could apply some force to compress the leads a bit, but not *tape*. – Chris Stratton Apr 26 '17 at 01:30