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IC Sockets...why? Easy question...

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Electric Rain

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I have a question that should be easy enough to answer. What is the point of IC sockets? I mean… are they for breadboards only? Perf boards? When I see pictures of circuits with ICs, I notice sometimes they have sockets, and sometimes they don’t… So why, when, and where are these sockets supposed to be used? Thanks.

Rain
 

samcheetah

New Member
CMOS chips are very sensitive to ESD (elctro static discharge) so if u use a soldering iron whose bit is not grounded the chip might get damaged. and some people who are not confident in their soldering skills (like me) use sockets for ICs. the reason is that if u dont have enough experience with soldering u might heat a pin of the chip too much which might change the characteristis of the chip. so first solder a socket, when it cool downs insert the chip. and for instance sometimes chips get damaged. in that case all u will have to do is to pop the chip out of the socket. if u had soldered the chip on the board u would have to desolder the joint which is a messy thing to do.

so basically its for the safety of the chips
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It used to be common practice for most commercial products to use I/C sockets - however, in the race to provide more for less money (resulting in the throw-away rubbish we get today!) they were dropped almost completely years ago.

If you are making something, you may as well use sockets, I socket everything I can - as a service engineer, I also fit sockets if I have to replace a chip - a socket is cheap compared with your time and effort replacing a chip (plus there's always the chance of damaging the PCB).

It's not a question of soldering confidence (I've been soldering approaching 40 years, and I would match my soldering ability against anyone!) - it's a question of convenience.
 

samcheetah

New Member
It's not a question of soldering confidence (I've been soldering approaching 40 years, and I would match my soldering ability against anyone!) - it's a question of convenience
when i said the thing about soldering confidence i was talking about myself (see the post i made). anyway i also said it is for convenience and safety of the chip.
 

bmcculla

New Member
One Time Programmable devices tend be socketed. This lets you make a firmware update by replacig the memory device. Flash and EEPROM combined with in system reprogramable parts has done away with this use for the most part.

Socketing any component interfacing with high power components is a good idea (for testing at least). I've acidentally popped a couple parts by touching the wrong wires together.

Brent
 

Electric Rain

New Member
Huh, thanks guys! That helps me out a lot, and it's very interesting too. I think I'll start using IC sockets. They sound quite handy. :)
 

Electric Rain

New Member
So... you can just pop in and pop out ICs if you use sockets? How firm do they hold?
 

samcheetah

New Member
yes electric rain u r right. u can pop out ICs from sockets whenever u want.

have u ever seen BIOS chips on old motherboards. they used to come in sockets.

they hold tightly because whenever i wanted to pop out a BIOS chip i sticked a screwdriver between the socket and the chip and used it as a lever (altho i dont think this is the right way).

sockets are like (but not identical) to breadboards. so the chip is quite firmly held to the socket.
 

Exo

Active Member
Electric Rain said:
So... you can just pop in and pop out ICs if you use sockets? How firm do they hold?
They normally hold quite firmly. The only thing you have to think about is when using sockets on components that get hot there might be 'chip creep'. By expanding when get hotter, and shrinking again when cooling down some chips tend to creep out of their sockets over the years (happened to chips on Pc motherboards before they started using smd for everything)

Again, this is only for power parts wich get hot or are next to some other part wich gets hot
 

Dean Huster

Well-Known Member
Socketed semiconductors

Here's a long story to illustrate a point about sockets:

When Tektronix began to produce solid state oscilloscopes, they socketed ALL of their transistors. When ICs were developed and used in the scopes, they socketed ALL of the ICs and transistors. In fact, in the "new" 400-series portables (e.g., 465, 475, 485), they even socketed the four tunnel diodes in the trigger circuits. The number of sockets exploded with the advent of logic analysis. All of the logic analyzers with their S-TTL and ECL logic were fully socketed. Needless to say, service was easy on all of these instruments. All we techs had to do was pluck out a transistor and throw it on the curve tracer to check it and put it back if it was good.

But sometime you'd get a problem where you'd pluck out a transistor, it checked good, you'd put it back in the instrument and the instrument would start working correctly. Intermittent transistor? Intermittent socket? Cold solder joint? So, you'd replace transistor AND socket to make sure. At Tektronix, we strove to fix the problem right the first time so that there were no callbacks and good customer satisfaction.

Enter the Japanese. They were threatening the low-end scope market. The Japanese had a marvelous track record. They would introduce products on the low end of the price range and capture that market and then begin working their way up the product line until they had cornered the marked share on it all, whether the cheap stuff or the expensive stuff. Don't believe that? Just check out what happened to the U.S. market for cameras, stereos, TVs, calculators, radios, tape recorders, video recorders, automobiles, etc.

Several manufacturers (Tek, Hewlett-Packard, et. al.) got together to decide if they could counter this oscilloscope threat. With the exception of Tektronix, none of them had the desire to commit corporate resources to a fight that they could very possibly loose. Alone, Tek went ahead with their project to counter the Asian invasion. Their goal was to produce an oscilloscope that was inexpensive to manufacture, yet was still high-performance and reliable. They had earlier replaced the Telequipment (a wholly-owned U.K. subsidiary of Tek) line with the notorious T900 series that resembled Hoover vacuum cleaners. This new thrust was in a different direction and the 2200-series of oscillosopes was the result.

To save money, the entire scope was made on one large circuit board. This board was then scored and snapped to form two other boards. One corner was folded up at a 90° angle to become the front panel board and another corner was removed to become the attenuator/preamplifier board. Knobs were reworked to be one-piece knobs with no setscrews or brass inserts. All sockets were eliminated as were nearly all connectors. A new high-efficiency power supply was used. The result was a very light-weight, low-cost, high-performance, reliable scope.

The first thing the Japanese had to do was lower the cost on all their scopes to below their manufacturing cost in order to sell them under the Tek price. Then they had to do a major redesign. The result? Tek succeeded in countering the threat. You don't see Asian scopes that can compete with the Tektronix product line. There are a lot of Chinese and Korean scopes out there, but in comparison, they're junk.

Now to the moral of the story. Tek, through all of its years of research, discovered that fully 80% of the problems they were having with their products was due to intermittent or open sockets and connectors. The high-end 7000-series and 400-series portables were socketed and were plagued with intermittents. The lower-end 5000-series and TM500-series instruments had few, if any sockets and had few problems of that type. By eliminating sockets and connectors, the entire Tek product line improved tremendously in reliability and the company saved a lot of money by not using sockets, saving another manfacturing step and eliminating a lot of parts.

The only parts that Tek ended up socketing were ROMs and EPROMs that might need periodic updates and expensive (at the time) microprocessors.

Do I socket ICs? When making PCBs, absolutely not. "B" series CMOS are much more forgiving that the older "A" series, so don't need sockets. Now, I DO use sockets if I build a circuit on perf board with point-to-point wiring, simply because replacing a defective IC (they are sometimes bad right out of the sleeve) would other wise be a very destructive process with that method of prototyping. And if you're using wire-wrap, you don't have any choice but to use sockets.

Dean
 
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