surface-mount resistor test socket

two thin pcbs each with two gold pads in the right footprint squezed around the resistor maybe glue some pieces of thin pcb on one of the pcbs as a guide on three sides of the resistor footprint ?

maybe a slit between the pads so it is more like fingers

made any sense?

-Lasse

The Farnell catalogue has a couple of pages of "spring contact pins" and "spring loaded contact probes and receptacles" both intended for test fixtures, where you drop a printed circuit board into the fixture and the sprung contacts make electrical contact with copper pads on the printed circuit board.

Presumably the force available is high enough to pierce any crud on the ends of the resistors.The thinnest receptacles might just be narrow enough to mounted close enough together to vertically probe an

0603 chip - to get a four-wire connection you'd either have to angle the probes in or clamp the resistor between two pairs of two-pin probes,

-- Bill Sloman, Nijmegen

We made a finger holder that has a Kelvin clip tips with the sockets on the back ends to connect to a DMM. We can pick up the piece and glance at the DMM and then place it on the board.

Works good for hand assembly boards.

Jamie

John Larkin wrote in news: snipped-for-privacy@4ax.com:

MIL-PRF-83446/10, which specifies chip inductors, has test fixture drawings on page 5 that I've adapted to do chip resistors and capacitors.

--
Bob Q.
PA is y I've altered my address.

There are some RF test fixtures around, from Coilcraft and others, but they may not be good for low-ohm precision resistors.

John

Why not use a pair of plastic tweezers with Kelvin connections on their ends?

--
JF

That's too complex for Larkin's small mind ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

Agilent 16044A looks like a good choice, but it's not particularly inexpensive.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

on

--
Perhaps, but be fair, instead of looking for retribution.

Would that work with 0805 and 0603 parts? Seems like that would be hard to handle. I was thinking it would be easier to pick up a part with tweezers, place it on a flat surface, and close in with the spring-loaded contact blocks.

There are lots of things like this around

where they press the part down onto planar contacts, looks like a PCB maybe. They are not explicitely 4-wire though, intended mostly for microwave measurements. We need something like a few milliohms of contact resistance to test, say, 49.9 ohm 0.05% resistors. Doesn't look speedy, either, not too well suited to receiving inspection.

John

Why do they do that? I wanted to see if prices were in the thousands or the hundreds and they want my life history to respond. Screw 'em.

on

Sure. As soon as Larkin stops with the "old" crap. (And publishes a schematic with component values ;-)

But, to be fair, we were doing the Kelvin tweezer bit at Dickson Electronics, 1970-73, on the hybrid line I ran. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I wonder how many web sites log the stats on how many people wind up at their registration page, and then go away.

I hear that many people are entering their country as Afghanistan, because it's first in the pulldown list.

That fixture does look expensive.

John

connections on

You're not old any more?

Have you stopped insulting my wife?

John

Most shops, and I assume yours included usually have means of doing small machining and fabing of special tools and jigs. Or at least you can get your hands on some one that does. Why don't you simply make an automation set up?

Not to long ago I did do such a thing using standard industrial PLC controls for an in-house testing unit as one of my consulting side jobs.

Of course the software maybe a little challenging which I wrote in Delphi to operate the visual camera so that I can move the chip caps around into place via a small X,Y axes arm with a miniature vacuums suction finger. All they had to do was dump a pile spread out on the table and it was seek out a piece, pick up and shuffle it into position for testing. It did this very fast.

I mean, you don't need to go all the way like that but you could instead use a conical spiral funnel that turns where it positions the pieces to move into a testing jig slot, from there the simple PLC program can operate a miniature pinch finger to clamp and apply a test.

If you're serious about doing things right for production then get serious about the tools you're going to use otherwise, don't be lazy and pick up the damn Kelvin tweezers and get to work! :)

Jamie

You should have access to the 'Control panel' for your website from the hosting company. It has a lot of useful information, including how long each visitor is on the site. It also tells you the operating system, and browser they use. You can see what countries they are in, and see how many 404 errors are generated from bad links or missing scripts which is important to check after any updates.

--
You can't have a sense of humor, if you have no sense.

I would start with gold plated contacts at the seating surface (maybe

0.001 higher) and use an insulating bar with spring loaded contacts that can be lowered accurately and easily.

If they were purchased from a reputable source and you didn't get what you ordered, why not ship the entire lot back and let them sort it out? I certainly wouldn't sign up to solve someone else's problem.

I was hoping to make a proper 4-wire measurement. Some of the resistors are 49.9 ohms, 0.05%.

John