SMT Soldering by hand

Archive BatchPCB
1

Hi All,

Firstly, what a great service! The PCB’s turned out really nice :slight_smile:

My question is regarding hand soldering using the method below.

In step 7 it says NOT to use solder with the reflowed board.

I assume this is because the solder used in manufacturing the PCB remelts.

Does this apply to BATCHPCB boards? or will I need to use solder?

Thanks all,

Alec

  1. Apply a thin coat of paste flux to the SMT pads on the board. The flux will help your parts

  2. Place your part on the SMT pads. Carefully align the pins so they appear to be centered in the pads. Take special care that you have located pin 1 on your part, and you have aligned it with pin 1 of your PCB. Aligning the part requires a little patience, but it shouldn’t be too difficult.

  3. Clean the tip of your solder iron with a wet sponge. There should be a nice clean tip without ‘extra’ solder on it.

  4. You should now tack your part in place. Only do 1 pin here as you will be checking the alignment in a seperate step. Touch your solder iron to a corner pin of your SMT part and let it heat for a couple of seconds.

  5. Repeat for an opposing corner pin.

  6. Recheck your alignment of all the pins. They should all line up as close to centered on their pads as possible.A trick that I like to use is to hold the board up to a light source to backlight it. This allows you to see how the pins align to the pads. It is also a great way to check for short circuits and solder bridges.

  7. Now that all of the pads are aligned, you can heat each pin on the part. Remember, you are using the solder reflowed on the board to mount the part. Adding additional solder is a tricky propostion that usually results in a messy solder bridge!

  8. Each pin gets a second or two of heat. I usually drag my solder iron across the pins slowly which heats each pin in turn.

  9. I will often go back and reheat the part one additional time, just to be sure I did heat everything. This shouldn’t take you very long.

  10. Check to see if you created a solder bridge anywhere by closely inspecting your work. I often hold the board up to a lamp so the light shines through the board (backlighting it). It helps you to see solder bridges and that everything is aligned.

2

I think what they are saying is that the boards from the pcb house already have a thin layer of solder coated across the copper pads. All you have to do is heat up the pin, which melts that solder and attaches the component.

In my experience, sometimes the existing solder is enough, sometimes it’s not. If it’s a very fine pitched device, I generally don’t add any additional solder. If it’s something larger, like a 1206 capacitor or LED, then I generally add additional solder to create a better connection.

c.

3

whittenburg:
I think what they are saying is that the boards from the pcb house already have a thin layer of solder coated across the copper pads. All you have to do is heat up the pin, which melts that solder and attaches the component.

In my experience, sometimes the existing solder is enough, sometimes it’s not. If it’s a very fine pitched device, I generally don’t add any additional solder. If it’s something larger, like a 1206 capacitor or LED, then I generally add additional solder to create a better connection.

c.

Hi,

Thanks for that. Thats exactly the answer I was after :smiley:

I have some fine pitch devices which I don’t want to use extra solder on.

I assumed the large comps would need extra,

Thanks again!

4

Flux helps a lot.