Help in soldering an SMD

I got the above boards from china. I had hoped that soldering the chip onto the board would be a breeze by these phone repairmen. However I am much wiser after 3 weeks.
So what do I do.
If I have to do it myself where can I find the reflow solder paste. By looking at videos on youtube I figured I use a syring to put a very small amount of paste on each pad just to TIN it. Similarly the ic leads should be tinned. Finally place the ic on the board and apply hot air.
Will it work.

Here is a better image of the imported components.

What exactly is the difficulty here? These are standard QFP packages and can easily be soldered by hand using suitable iron and soldering wire.

No difficulty Asad. Just hesitation. Want to learn to do it.
Anyway I got one piece done by a mobile repair shop. In the process found a source for solder paste. Brand name is Mechanic. Will buy it on my next visit to college road.
It is really cool to see the ic snuggle into position when the solder melts. I HAVE TO DO IT.


In SMT world, these ICs are very big (mota mota kaam).

These are very easy to solder, since pin to pin spacing is large. IMO, you even don’t need solder paste, solder wire can work here.

The key to success is flux, lots of flux (paste form). If bridging between the pins occur, it’s easy to remove using a copper braid. If braid is unavailable, you can strip a multi strand copper wire, dip in the flux and use as a braid to absorb excess solder and remove the bridges.

In case you need the actual reflow solder paste, I have that available.

Just for your information, I have a proper SMT pick and place line installed for professional work. In case you want your stuff soldered, you are welcome.

Jazak Allah Ijaz.

As I said earlier part of the hobby is to learn this new technique. The mobile techie did one piece with a normal soldering iron. I know now that I can do it that way.
But the other part about learning a new technique is unsatiated. So I want to do the rest for that reason.

For my guidance where can I buy the solder paste in Pindi. I need, say about 10 gms or so. Info on which brand name to buy is much appreciated.

I am not sure about the local source, but I import for my own use and mine is in jars of 500gms.

Can fill a syringe for you, no charges :slight_smile:

Oh, ok. :slight_smile:

Working with solder paste on such packages can be tedious and there is high chances of solder bridging (especially with 0.5mm or lower pin pitch). It would be an interesting learning experience. Good luck with your endeavor!

I found it difficult for the College Road shops to make a PCB for me. This is understandable because its a very small non-commercial order.

So I decided to do it myself. I ordered toner transfer paper from aliexpress (2.5US$) for 20 sheets and free shipping.

Now I have unsuccessfully tried toner transfer in the past. My take for this was that both temp and pressure using a common household iron, are dodgy. So I have been thinking what to do. Here is my answer.

These are the unit tyre puncture repair wallahs use. It has a heater to vulcanize the puncture patch on the tube. Planning to use it for applying even pressure. Temp. control is a trivial issue since it is electrically heated by an element of 750 and 450 watts.

Will keep you posted.