Lubricating IC sockets and female headers?
rwgast_logicdesign
Posts: 1,464
So the other day I was messing around with some boards I made a while ago. I needed to pull the propeller chip out of one of them, I usually socket all my IC's with pretty cheap 3M brand sockets.The particular board I pulled a Propeller chip out of has had all the chips seated in it with out removal for close to a year. I used an extractor tool for DIP ICs, the kind that look like big tweezers with hooked ends.
Anyways the chip seemed to be stuck in the socket pretty good, it was a lot tighter than normal. I tried slowly removing the chip by putting pressure on one side of it, then pulling up a little then putting pressure on the other side and pulling up a little, and so on (I guess walking it out may be a good description) until the chip was removed. Well the TX pin on the Propeller was stuck in the socket so tight when I removed the Propeller the TX pin stayed in the socket instead of staying attached to the chip. I easily fixed it by soldering some bare copper to what was left of the pin.
I was wondering how to prevent this from happening in the future. I saw a bottle of non conductive lubricant at Radio Shack but it seemed a bit expensive and the bottle was much bigger than I needed. So I was wondering if there were safe lubricants commonly found in the house, wd-40, electric razor oil, electrolytic spark plug grease? I am kind of worried that even if they do not conduct they may cause corrosion or something. Maybe there is a way to prevent this without grease?
Anyways the chip seemed to be stuck in the socket pretty good, it was a lot tighter than normal. I tried slowly removing the chip by putting pressure on one side of it, then pulling up a little then putting pressure on the other side and pulling up a little, and so on (I guess walking it out may be a good description) until the chip was removed. Well the TX pin on the Propeller was stuck in the socket so tight when I removed the Propeller the TX pin stayed in the socket instead of staying attached to the chip. I easily fixed it by soldering some bare copper to what was left of the pin.
I was wondering how to prevent this from happening in the future. I saw a bottle of non conductive lubricant at Radio Shack but it seemed a bit expensive and the bottle was much bigger than I needed. So I was wondering if there were safe lubricants commonly found in the house, wd-40, electric razor oil, electrolytic spark plug grease? I am kind of worried that even if they do not conduct they may cause corrosion or something. Maybe there is a way to prevent this without grease?
Comments
Machine pin sockets are great but I really haven't had too many issues with regular DIP sockets. I would guess that 3M should be ok but I normally use AMP or some other well known brand. Dual leaf sockets (that make connections on both sides of the pins) seem to make it easier to get the chips out. To remove the chips I usually use a very thin bladed screwdriver and also have a small pick set (straight and 90 degree) that can help start get the chip out. You can free each side then carefully pry them out. Personally I think the chip extractor tools aren't worth using and more often than not one end would slip off and you end up yanking out one side of the chip and bending a bunch of leads. I may still have one or to but never use them.
If the 3M sockets you have aren't working for you then try a different brand. The difference in cost will probably be about the same as you trying extra sprays, etc. I'll mention it again, I really, really dislike any kind of junk sprayed on a board (unless it is some no residue cleaner or flux remover) and would avoid working any any boards that someone sprayed lubricant on.
I can see perhaps tuner cleaner for old TV tuners but it doesn't belong on any of the circuit boards I make or repair.
No kidding, actually.
About 20 years ago I got together with a group of people and bought a fluid ounce of pro-gold and still have a lifetime supply of it left so I have to admit I don't follow the offerings of Caig labs that closely. I do know they sell their products directly and through at least Frys and some Radio Shacks. If I lost my bottle of pro-gold I would go to the website for Caig labs and go through their offerings of current products.
The stuff I have is an oil and after cleaning the connections leaves a very thin film of oil to prevent corrosion in the future!
Since I plug and unplug my Prop chip quite a bit, (I'm an experimenter), I don't want to damage it. I mean it is a bit expensive.
So I take a much cheaper machined pin socket and plug the Prop into it. Now I'm free to plug the reinforced Prop in with abandon.
Besides, if I wreck a pin on the socket it's easily replaced.
Duane J
EDIT: That's it!!!! I thought I was the only one that ever heard of it.
An IC puller is handy and will cost $1.20. http://www.futurlec.com/Tools-IC.shtml I bought a pin straightener too (scroll down that page) - very handy because all ICs have their pins bent out too far for sockets and the pin straigtener bends them to the correct position.
Which might also be part of your problem - if the pins are pushing outwards too much the chip is harder to get in and out.
Re machined vs cheap sockets, call me strange but I prefer the cheap ones as I think the chips are easier to remove.
Getting chips out - wedge a flat screwdriver under one end and rotate it. Then do the other end. Walk the chip out a little bit at each end at a time. Less likely to bend pins.
Lubrication? Many are covalent solutions... they don't conduct electricity. Others are ion solutions... they conduct electricity and corrode. If you really feel the need to lubricate... maybe a two step process is the wisest.
First, use a spray that lubricates the sockets to get the IC removed.
Second, use a spray cleaner that is neutral to remove all residue.
Frankly, I don't think any DIP ICs were ever intended to last more than 20 or so years. So the sockets and the chips themselves are not very rugged. I just replaced my air conditioner and the old one had a bad UNL2003 chip due to corrosion from the moisture... at least one pin completely rotted away in five years of use. And all the push buttons on it had failed much sooner... I just relied on the remote until I went in and replaced the UNL2003 and all those little buttons.. just to see if I could repairf this in a DIY.
When the new one arrived, the electronics were running perfect, but the cooling coils were rusted out and only the fan was working. It is a consumer product... it ain't supposed to last. That is why the Delorian stainless steel car was so unwelcome to big car makers. They love regions that salt their roads in the winter.. more sales. And with chips... we keep going to finer and finer pitch that obviously makes the corrosion issue more dire.
In sum, built-in defects all around.
If I do have to plug and unplug a chip numerous times I do what Duane suggested, plug the chip into a socket, and plug/unplug the socket.
These days we have a lot tin or even gold plugs. So I am not sure than an anti-oxidant is going to work as well. I just use a German spray product called Kontact for nearly everything. But if I am concerned with residue, I use a spray can of tuner cleaner as TV tuners require zero residue clean up. Anything left behind might affect the accuracy of their induction coils.
Fine pitch ICs do have special problems with solder bridges or dirty. I have a working monitor that has a very fine pitch IC that requires cleaning about every 6 months or so. I am at the point where I am fed up with cleaning. So the next step is to get a bottle of nail polish lacquer (clear or red or whatever) and protect the leads after the next cleaning.
Why use nail polish lacquer on electronics? Well, it is intended to be later removed with acetone. So if you make a mess or need a repair, you can easily get the residue out of the way. Acetone is generally a more harmless solvent than alcohol... though it does dissolve vinyl, but not too quickly.
The spelling may very well have been cramolin. It's been a long time since I've seen the spelling of the stuff. I don't remember it being intended to make chips easier to insert or remove. I mostly used it on pots and connectors for low level analog voltages. That was back when I worked in factories dealing with process controls. The heat, humidity, dust,etc did a number on connectors and pots. I still use the pro-gold I have on computer memory.
It has been a long time since I used it as well so your spelling has as much chance of being correct as mine. IIRC it was a red colored liquid in a red bottle about the same size as that used for eye drops.
The instruments I serviced had around 10 - 20 boards with around 30 - 40 socketed chips per board. The major part of doing a PM was spent on tightening the motherboard connector pins ( Y shaped 2 x 22 per board ) and removing and reinserting all the IC's on each board. By using Cramolin or Stabilant 22 on the IC pins they only had to be removed/reinserted once a year instead of every 6 months which was a big time saver.
Thankfully they eventually started to solder the chips directly to the boards. That was a big step up in reliability.
Yes, but sockets have other benefits in prototypes. Heat protection is way down the list.
They allow quick alternative testing, and also reassurance-swap, when you suspect you may have fritzed something, but are not sure.
On the Topic of lubrication, I once found Millmax have part codes for lubricated PLCC sockets - but stocks are hard to find.
So it is done, and even to a commercial order-code level.
FF
Wiremaster sounds like a great tool for wire wrapping. Back in the day when I did a lot of wire wrap I used Supercalc on CPM to create a net list from hand drawn schematics. Now you can probably print the net list from a schematic capture program to a file using a generic acii print driver and import that to a spreadsheet. Not as good, but somewhat helpful.
What I really miss was the wrap tool that slit the insulation as you wrapped it around the post, and let you go from post to post without cutting the wire. You could connect a dozen posts in a minute or two.
Yes having to rework a proto board is a pain in the butt, but I think the point is to try to avoid that by testing your circuit on a bread board then transferring it to the p2p board. When a small mistake has been made and needs to be fixed I would imagine it would take less time on a p2p board than it would ripping layers of wire out to get to the mistake, and then re wrapping all the wire you ripped out once the mistake has been fixed.
I can wire wrap connections directly to IC sockets (wire wrap type) and
directly to resistor like components.
After my connections are wrapped and confirmed correct, I usually lightly solder the wrapped connections.
If I make a mistake in my connections, I cut the wire wrapped wire and pull it out, then rewrap correctly.
Repairing mistakes is easier than point to point wiring corrections.
Sorry I don't have a photo of past wire wrapped projects.
@ RW, How many bread board modules would you need to proto out a 200+ mixed ssi, msi, and lsi on a breadboard. now that would be a testing nightmare come to life. wirewrap far more reliable than breadboard. also much quieter than the breadboard. Many of the development tools and simulators were north of 6-8 digits exclusive of the decimal point in the '80s and into the 90's. We are spoiled with the stuff out there now...... I still like wirewrap for testing ideas
No arguments here, although if I had my original strip and wrap wire wrapping tool I might be tempted to wire wrap some of the simpler "one of a kind" digital boards. Once any needed testing/rework of the board had been completed the connections could be soldered for reliability.
That is very close to the tool I was using. The only difference is that it would slit the insulation as it wrapped it around the post to get a better contact.
Here are my 10 commandments before installing the boards:
1 - Always route the wire so it comes to the pin from outside the chip/socket.
2 - Wrap two or three turns around each post.
3 - Connect 0.1uF bypass capacitors between chips in a row.
4 - Connect and power and ground.
5 - Solder bypass capacitor, power, and ground connections.
6 - Verify the power connections by applying power and measuring voltages before continuing.
7 - Make the connections specified in the net list.
8 - Verify connections with an ohm meter before continuing.
9 - Test the board for correct operation and make corrections as needed.
10 - Solder all the connections and retest before installing at customer site.