Looking for 8 pin DFN socket or cheap solution

[lilimike]

Does anyone have a solution to program an 8 pin DFN chip?

Microchip has one for $160 but that's way over my budget.
I have found similar elsewhere for $100 but still over my budget.

Obviously if I am going to build a circuit with a DFN package it is to make the circuit as small as possible so I don't want to add the extra components and header for ICSP.

Mike

[Allister]

Well if $100 is over your budget for an exotic adapter, then my only suggestion would be drilling some holes in a slab of plastic and inserting pogo pins, layer up some alignment tabs to position the chip and with a little finger pressure you should get something to work. Or you could do the same with a generic DFN board just tin the pads, drop the chip on top and apply pressure while programming.

Certainly not an ideal solution but in low volume it should get you by.

[lilimike]

Allister,

I tried to design a small PCB with some small wires soldered on their sides matching the pads of the chip. Tinning 8 pads and expecting for them to be all the same thickness seams kind of hard to do. Nevertheless my plan did not work because it is a small small world but you gave me a good idea. I will design a PCB which will contain an ICSP header and insert pogo pins to line up with some exposed traces on my production PCB and I will simply press this programming PCB to program the chip on the production board.

That should work fine.

Thanks for the tip.

Mike

[Allister]

I will design a PCB which will contain an ICSP header and insert pogo pins to line up with some exposed traces on my production PCB and I will simply press this programming PCB to program the chip on the production board.

That is the way many shops test boards before placement into the housings, I know when I worked at a shop that was the way we ran test on the boards before placing them into the housings. You used to see a lot more test pads for this purpose on pc boards, seems now you mostly see in used for in house jtag interfaces.

And if you want to get real cheap rip apart some dollar store wrist watches for the spring loaded pins that hold the band to the watch body. A poor mans pogo pin. Yes it does work, 10 or 15 years ago pogo pins were much harder to source than they are now, so you had to get by with what you could find.

As for getting the pads even after tinning them a quick file across the top will level them off, but the pogo pins are still a better option, a common plastic cutting board makes a great plastic slab to drill and hold the pins into.