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programming QFP/TQFP microcontrollers

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jimkess

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Hi,

How does one program QFP/TQFP microcontrollers? I mean, does one solder the QFP MCU onto PCB and use ICSP to program them? Are there zif socket available for such package microcontrollers? Any tutorials links would be helpful.
 

You just connect an ICSP programmer by cable to the board and that's all.
There is no need to have ZIF soquets on board.
 
mounting QFP/TQFP microcontroller onto PCB seems scary but want to try, any special tools i need to be aware of?
 

QFP/TQFP...?

A reflow station, solder paste, hopefully a very steady (and quick) hand to put the paste on the board before it dries too much, a quality soldering iron with a very narrow tip to fix the inevitable solder bridges caused by adding solder paste by hand (I doubt you're going to want to create a solder stencil for a one off board.

Don't touch any of the leads of the QFP/TQFP they are quite fragile and if they get bent from the plane of the mounting surface you will likely get even more solder bridges.
 
Do you already have a design or are you just starting out and wanting the experiment?
If you have the design then you will need to check that the ICSP pins are not connected in such a way that the programmer's signals are interfered with. Check the documentation for whatever programmer/MCU you are using.
If you just want to experiment, then I know that you can get QFP prototyping boards (Schmartboard has some for example - probably many others) where you can solder the MCU to the board and then connect to the larger-spaced pins on the edge of the board. Some boards (again I've used the Schmartboard in the past) have pre-soldered and fairly deep channels for the MCU pins which makes the soldering easier.
Susan
 
thanks for the tips,

i am trying to learn in general working with QFP mcu and smd

i have already ordered what i think is called QFP prototyping board, a board where each QFP mcu pins are spread out to bigger and spacier pinouts.

but for home made made pcb i think the problems will come from 1) heat amount(temperature) applied which could damage the mcu and 2) the spacing between the mcu pins
 

Hi,

There are a lot of tutorials and videos on soldering SMD for hobbyists.

You may use a kitchen hot plate, or an kitchen oven...or other heat source.

If you are worried about heat... many device datasheets contain soldering temperature charts.
Every datasheet should at least contain informations about max temperature.
And the manufacturers give additional soldering informatiins on their web pages.

We (professionals) need to read them, too.

Klaus
 
They can be hand soldered with a fine tip iron, small gauge solder, flux, and a decent magnifying glass. I can do 0.050" pitch reliably.

1) Apply flux to pads.
2) Place part and align the pads in 1 corner. You want to center the pads on both the X and Y axis.
3) Touch a single corner pad to tack-solder the leg. Hold with one hand and tack solder with the other. The boards I get have enough solder tinning to not require a third hand for additional solder. Add a tiny bit of solder prior if your board needs it.
4) Go to the diagonal corner and do the same thing. Only tack 1 pin.
5) Inspect all the remaining pins to make sure they are centered on the pad. Adjust the 2 corners as required.
6) Once everything looks good, tack a few more pins to hold everything in place.
7) Start soldering the pins. Use tip to heat the leg and apply solder to the pad. It doesn't take a lot of heat or solder to get it to flow.

Since I'm right handed, I always start from the left-most pad on a side. Since the iron is angled on the right side of the pad, it helps to not already have solder on the next pad to the right (at least for me). If you happen to bridge a pin or two, apply some flux and use fine gauge solder wick. If you have a bridge up on the legs, don't press the the wick against the legs. If you press against the legs, they could bend and/or lift off the pad. Press it down onto the pads and it should wick down. This will also help keep the legs in place.

If you are laying a new board out, throw a few SOIC packages in to practice with. The same method applies but the pins and spacing is larger so you can get the technique down.
 

YouTube is full of videos showing how to solder SMT packages, including some difficult ones.

These videos can provide much more information than we can provide with a simple forum reply.

Then, depending on your skill and the tools available to you, you may choose the techniques which are best suited to your project.

One thing I should emphasize: practice first on a sample board the first time you attempt a new technique.
 

spudboy488 said:
They can be hand soldered with a fine tip iron, small gauge solder, flux, and a decent magnifying glass. I can do 0.050" pitch reliably.
Click to expand...

I applaud those of you with the skill to do this kind of work. My hand is not steady enough to do anything even close to this kind of work let alone the really fine pitch stuff.:thumbsup::clap:
 

Hi,

I do it like in this video. It really works, it is no fake.
But you need good equippment, good quality PCBs, solder, flux and ICs and you need to select the correct temperture.
https://www.youtube.com/watch?v=6PB0u8irn-4

And one needs some experience. Many ICs and many month of hand soldring.

Klaus
 
Klaus - I solder QFP devices by hand but I'll be trying the technique in the video you liked to. Thanks.
Jimkess - I would suggest that you get a few 'test' chips so that you can try soldering them yourself. It takes a bit of practice to get it right so you want to (hopefully) be over the initial steep part of the learning curve before you try on your actual device. Also practice cleaning up the solder bridges that will inevitably form.
Susan
 

spudboy488 said:
They can be hand soldered with a fine tip iron, small gauge solder, flux, and a decent magnifying glass. I can do 0.050" pitch reliably.

1) Apply flux to pads.
2) Place part and align the pads in 1 corner. You want to center the pads on both the X and Y axis.
3) Touch a single corner pad to tack-solder the leg. Hold with one hand and tack solder with the other. The boards I get have enough solder tinning to not require a third hand for additional solder. Add a tiny bit of solder prior if your board needs it.
4) Go to the diagonal corner and do the same thing. Only tack 1 pin.
5) Inspect all the remaining pins to make sure they are centered on the pad. Adjust the 2 corners as required.
6) Once everything looks good, tack a few more pins to hold everything in place.
7) Start soldering the pins. Use tip to heat the leg and apply solder to the pad. It doesn't take a lot of heat or solder to get it to flow.

Since I'm right handed, I always start from the left-most pad on a side. Since the iron is angled on the right side of the pad, it helps to not already have solder on the next pad to the right (at least for me). If you happen to bridge a pin or two, apply some flux and use fine gauge solder wick. If you have a bridge up on the legs, don't press the the wick against the legs. If you press against the legs, they could bend and/or lift off the pad. Press it down onto the pads and it should wick down. This will also help keep the legs in place.

If you are laying a new board out, throw a few SOIC packages in to practice with. The same method applies but the pins and spacing is larger so you can get the technique down.
Click to expand...
i liked the idea of tagging two pins to hold them at first. i think i saw this trick in one of youtube video but many months ago when i was curious about this.

- - - Updated - - -

yeah, for sure i need some practicing chips. i even don't know what chips i should use. i only ordered the QFP chip that i needed. BTW, what are the typical sizes of chip capacitors and resistors? I know that they are called by some size names. I have to order some SMD chips(resistors, cap, digital components) to practice.
 

Hi,

resitor sizes.
0805 should be no problem for hand iron solder. (one pad with solder, then align the chip and heat this pad - without new solder, then solder the other pad)
but usually I use 0603. More difficult to hand solder, but I do this only for prototypes.

With a hot plate, stencil and solder paste ... 0603 should be no problem. With correct pad dimension they align themselfs...

Klaus
 
I am 61 years old, with a tired eyesight, so I only do 0805.
If you are young, you should have no problem with 0603.
 

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