| Electronics > Projects, Designs, and Technical Stuff |
| SMD resistor socket (2512,1206,0805,0603) |
| (1/4) > >> |
| OM222O:
Hello I have designed a milliohm meter which works great. I wanted to have an easy way of measuring resistors without using probes, so I made these tracks directly on the front panel which go between the force and sense terminals: However after getting the PCBs, I found out that they are very fiddly and practically slower than just using the probes, as I have to put a lot pressure at the right angle to get a good connection which in hindsight is pretty obvious :-DD I searched a lot for a socket that can fit resistor packages, but I can't find anything. there exist modules for SOIC or TQFP packages, but nothing for the standard resistors. If I can't readily buy the sockets, is there a trick I can use on the PCB instead? I thought about having spring contacts that are really close together, but for the larger sizes it would again be really difficult to fit them, unless I have 3 sets of springs contacts which I don't have enough space for :-- |
| ataradov:
You will have much better results if you remove the solder mask from underneath the components. The solder mask is pretty thick and the component will just rock on it. Scrape it from the boards you have and see if there is a difference. |
| OM222O:
I will give that a shot, but I'd still like to have a better solution. thanks! |
| DaJMasta:
Will definitely do better, you could try to solder on sort of tiny bus bars so that the only contact point is on the pads not the chip, but to get a good representation of it you'd still need pressure from the top. Maybe some sort of clamp? A board like this on the bottom, no solder mask, a thin board or other bit that just has suitably sized cutouts for SMD parts in line with the pads arrangement (to keep the parts contained), then a second board that comes down on top, sandwiching the part. Spring load the thing in a jig and you could probably even use the two contacts on either board for four wire measurements of reasonable quality. You can't really use your hands for the pressure if you want it to be accurate into the 100s of k Ohm range, but it probably does the trick fine when in very low resistance ranges. I would be weary that finger gunk could eventually make the contacts on the board a bit gummed up which could effect measurements if you were holding the parts down each time. I think the usual approach for component measurement is precision machined contacts in a clamp from either side and then a low leakage dielectric holder piece, there are LCR and impedance measurement test fixtures that can give you a good idea of what the test equipment companies think work well. This approach with no solder mask is a cheap and simple alternative that's used in a lot of component testers for SMD parts. |
| OM222O:
very interesting idea about using a PCB as a jig with suitable cutouts! I will try to do that but obviously I need to change my layout for that. I had a look at the clamps, and they are seriously expensive! about 100$ while the board costs about 20$ ... so that's a no go :-DD What if I want to get some sort of plastic clamp manufactured with some copper inserts embedded in them? this is a product that I plan on selling so I can get custom parts made if they're not 5x the price of the product itself :-+ |
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