How to solder this IC (I/SS) on the PCB?

dl324

Joined Mar 30, 2015
12,668
Rotated, cropped image:
clipimage.jpg

Assuming the lead pitch matches the board, I'd go with solder paste and a hot air tool.

If you don't have them, apply flux to a row of pins and drag a blob of solder across all of the pins with a soldering iron. If you end up with shorts, reflow the solder to clear them.
 
You can solder it with soldering iron, first solder upper left pin (usually pin1) and then lower right pin (diagonally). But you need:
1. soldering iron tip 0.4mm (chisel form)
2. flux pen to coat PCB pads
3. presolder first pins (upper left and lower right ones) to better contact with PCB pad
4. steady hand
 

BobaMosfet

Joined Jul 1, 2009
1,501
First, look carefully at the breakout-board and make sure you understand which pins you need to sit the IC on. After that, you can do this with:

  1. Candle-warming Hot plate
  2. Chip-Quick low-melt-point solder (syringe)
  3. Toothpick
  4. Solder Flux
  5. Hot Hair Dryer

Steps:

  1. Once you know what pins, use a toothpick and spread chipquick across the pins on the breakout-board. SPARINGLY. less is more. Just enough that it will bead and wick to a pin on the IC when it's hot enough.
  2. Dab a fair amount of solder flux _gently_ so as not to disturb the solder. It can be a small puddle where the IC will sit.
  3. Sit the chip on the appropriate pins, and press very slightly to seat it into the paste.
  4. Put it on the candle warmer, turn the candle warmer on and walk away. Leave it for an hour, so it heats everything up.
  5. Take a hair-dryer, hold it several feet away from the chip above (too much air pressure could blow the IC away, if too soon). Point directly straight down, so the air pressure is straight down, turn it on, let it get hot, and very slowly move it towards the hotplate until you see the solder bead up, wick around the pins, and then lift the hair dryer back straight up and turn it off.
  6. turn the hotplate off and walk away. let it sit until cool.
  7. check using a magnifying glass for any bridges, but if done properly, the chipquick and the flux will have worked together to pull towards the pads & pins, and you will have a nice, neat little soldering job.

This works. It's how I did it before getting into air-reflow/rework for single-ic to single break-out boards like you have.

Best of luck.
BM
 

dl324

Joined Mar 30, 2015
12,668
Last edited:

Yaakov

Joined Jan 27, 2019
2,341
Did he ever get to the point? His technique was terrible and his tip was too large.

A lot of videos are unnecessarily long because those so-called experts are just trying to monetize your time.
Drag soldering often uses a larger tip. You can find other examples of how-to videos explaining it. Maybe you prefer this one:

 

dl324

Joined Mar 30, 2015
12,668
I was skeptical about drag soldering but for high pin count packages it's way easier and works well.
I've seen the technique used many times, but I never had to resort to using it because I have paste and a hot air tool.

The second video was clearly by someone who knew what he was doing. The first guy seemed like he was making it up as he went. Another of the so-called experts who's quite clueless himself...
 

Yaakov

Joined Jan 27, 2019
2,341
I've seen the technique used many times, but I never had to resort to using it because I have paste and a hot air tool.

The second video was clearly by someone who knew what he was doing. The first guy seemed like he was making it up as he went. Another of the so-called experts who's quite clueless himself...
I probably should have vetted that video further, I only was watched the beginning and he had the right materials, and I counted on the Digilent imprimatur to vouch for it. Maybe they need to be more careful...
 

Yaakov

Joined Jan 27, 2019
2,341
That is not very fine pitch and you can do it with a soldering iron with a fine tip.
I prefer not to do drag soldering. If you bridge adjacent pins it can be difficult to remove the bridge.
The tacky flux prevents bridges very well. I wouldn't do it the first time on an irreplaceable part, though.
 

nsaspook

Joined Aug 27, 2009
8,156
I usually flux and drag solder the fine pitch pins of a plated board first to create a series of slightly raised solder bumps, then I use an hot air gun to solder the chip to the board as the board bumps melt and bond flat to the fluxed chip leads.

PXL_20210323_144923817.jpgPXL_20210323_144621260.jpg
 

Yaakov

Joined Jan 27, 2019
2,341
I usually flux and drag solder the fine pitch pins of a plated board first to create a series of slightly raised solder bumps, then I use an hot air gun to solder the chip to the board as the board bumps melt and bond flat to the fluxed chip leads.

View attachment 234882View attachment 234883
This is an excellent compromise for a neophyte with a high value one off part, even if an iron was used to individually solder the pins. I never though to do this, but it's clever.
 
Top