Doing a lot of SMD boards these days, and with them getting smaller and smaller, I find my designs needing 6-pin ICSP connectors to program PIC chips being the largest component on the board, often increasing the overall width of the board just for this as I use standard 0.1" pitch pins.
I had a thought the other day (rather obvious) to use smaller connectors to program the PICs and make a cable to plug into the small connector and the PicKit. My question is, whats the smallest and cheapest 6-pin SMD connector I can get without the need for a special tool to make the cable up, or that is a cheap tool (less than £50)?
I’ve had a look around at a few but find it hard to find SMD connectors and pairing cable plugs etc… so wonder if anyone has already thought of this and uses really small SMD connectors for anything?
I simply use five pads with 0.1" spacing and solder five SIL header pins to them, so that they are flat on the board (no holes), with an adapter for the ICD 3. A smaller, arrangement is possible with 0.05" spacing connectors like those made by Mill-Max. The connector could be on an extended piece of the PCB that is broken or cut off.
Depends how small you want to make it. A few suggestions that I use:
2x4 sized 0.05" SMT header, with an IDC connector on the cable side. Very easy to make the cable, since it’s just a smaller IDC… (Same idea as the common 0.1" IDC connector, but smaller)
use a 6 pin JST style connector, I use 1mm spacing SR-series connectors in several of my designs now, and is probably the smallest I’d go without special tooling. You don’t really need a special tool to put the cable in the connector, but you do need to source the correct wire for the size you end up settling for. http://www.dpcav.com/data_sheets/jst_sr.pdf
Use a flat flex cable and flat flex connector. A 0.5mm Flat flex connector SMT’d onto the board is all you need to bring the programming signals out.
(Note, I like samtec as they give away free samples… The links are more for reference, you can find local suppliers for similar things if it’s more convenient.)
Cool thanks I’m just in contact with samtec now about my requirements, they seem very cool just what I was after, just hoping the sockets are cheap enough, else I’d probably just leave the socket off and make the copper strips directly on the PCB in the right pitch and order and press the cable onto it for programming.
I dont quite get the pins idea. Are they not just going to fit in normal 0.1" holes, which means its no different than the original problem of the header size taking up a lot of space on the board. I don’t even solder the headers on some times just press the pins on, but thats not the problem its the size of having 6 0.1" pads.
I’ve never used them - but it seems to me as if you wouldn’t need to have the pads for the pins to land on all in a row. (1) (2) (3) (4)
The traces could come off the uC a short distance and find a convenient place to make a landing pad for the probe in a area of the board that isn’t used.
I would expect the pad not to be much larger than than one side of a 0805 I would think.
Awesome a test clip that would be perfect. Now all I need to do is find a 20 pin SSOP clip as can only find DIP and SOIC so far. That would then save on connector costs and PCB space too!
What about making my own from single core wire and fibreglass? Would probably take a few tries but sure its possible. Would probably make a PCB with the pitch of the 20 pins and then drill small holes in where I solder single core wire. Align them with the PIC pins so its in place, then dip in fibreglass resin a few times. Once I have the “in-between” bits filled with resin I can build it up from there into a shape that can fit over the PIC and slot into place. What do you think?
It would probably be a PITA to make your own and you would be constantly fixing it from wear and tare.
I dont see any reason why such a thing wouldn’t exist all ready. There is a mod chip product for the Nintendo Wii called “wii clip” which is exactly what it sounds like. It went over a .5mm pitch TQFP.
