QFN 32 Package Manual Soldering

[khanna_gunjan]

qfn32

Hello All,

I am using a RF Chip with QFN 32 package. the problem is I have no idea how i can solder it properlz as the pins are all under the chip. I do have a Hot plate and the solder pump (but the noyyel is too BIg) but i don't have the stencil for this PCB, so when i applz the solder with this dispenser it is either too much or tooo less and the soldering is not proper.

As the PCB is still in the prototzpe stage i dont want to spend on getting it done from outside or buz a new hot air station.. which will be too expensive for me.

Please suggest the possible solution. Thanks in Advance.

Gunjan

 

[VVV]

qfn-32

You can try to build a temporary stencil, out of a sheet of metal, and just drill holes in it, where you need to deposit the solder paste. Start with smaller holes and if there is too little paste, make the holes larger. (It's not easy, but with a good drill press, careful measurements, and LOTS of patience, it can be done).

Use a butane torch to heat up the device for about 3sec. This is the best I can suggest. I tried the butane torch method on QFN-16. It worked in 80% of cases.

 

[khanna_gunjan]

qfn32 package

thanks, but the problem is i presently have no such tools available with me.. or you can say its a project i am doing at home for hobby; so any other ways to solder such critical part.

And one more thing why do i need to heat the part with the butane torch.. will a hot plate not work.

 

[VVV]

qfn 32

Sorry, I don't know of any other way.
By the way, the time was 30 sec, not 3 sec.
I cannot see how you would use a hot plate to heat up only the part you need. With the butane torch, you have relatively small nozzle that heats up a small read, just the device you need.
Building the temporary stencil requires some careful measuring, a good drill press and tiny drill bits (0.25mm or so). Pretty expensive stuff, although a watchmaker may be able to help you out.

 

[waleedpcb]

qfn-32 package

Dear:
You can use a traditional heater, not hot air M/C, i also had that QFN and i solder it using a traditional heater.

waleed

 

[rikie_rizza]

qfn32 footprint

Soldering QFN is not that hard but its not easy too.
Heres the easiest way:
1. Make sure you have the precise footprint on your PCB, clean and flat.
2. Put a tiny bit of solder on the QFN pads. Ensure that all pads and expose pad are evenly soldered. if you apply too much, suck it out. The height must be the same, if not the result wont be balance.
3. Put the soldered QFN on the PCB with, of course, the pads align with the footprint.
4. Use a tweezer to hold the device. use your solder iron to heat the device in either of 2 way:
a. Place the solder iron on top of the QFN device until the solder melts.
b. Heat up the footprint and make sure some solder melts so the device stick on the pcb.
5. Apply more solder at the finishing stage.

I know that you're confuse...just try!

 

[kayaoo]

Re: qfn32 footprint

4. Use a tweezer to hold the device. use your solder iron to heat the device in either of 2 way:
a. Place the solder iron on top of the QFN device until the solder melts.
b. Heat up the footprint and make sure some solder melts so the device stick on the pcb.

Would the chip be over heated?

 

[Rob B]

I recommend hot air for this task.

Here are some pictures of how I fitted a 3mm x 3mm, 0.4mm pitch, MAX9814 QFN14 to a PCB.

The brown tape is Kapton tape which is heat resistant, the first picture is my makeshift 'solder mask' - I tinned the pads. During reflow I put a little light pressure on top of the device. I placed a small blob of solder on the centre pad also.

Yes, it worked first time .