Socket to Me?

[toml_12953]

How do you feel about socketing chips on PC boards? Sockets do make chip replacement a snap and protect chips from the heat of soldering but some socket types suffer from "chip creep", especially if the board is in equipment that will be subject to a lot of vibration. Also, sockets raise the profile of the chip.

I usually solder most common chips in directly, only using sockets for very expensive and/or rare chips or chips that require programming such as EPROMS, FPGAs, CPLDs.

I'd like your opinion on the subject, however.

[BillBee]

I voted yes but here is my only grain of salt. The items I have socketed are usually analog guitar effect pedals. If I do an IC replacement I generally socket it out of habit so if needs be I can swap it out at a later time without touching the pcb.

-Bill

[DA74254]

You forgot one vote button "Depends on purpose".
I do tinker a bit with microchips and microcontrollers and so long as I'm a clumsy amateur, I prefer DIP's.
If I want to make something waterproof and epoxy in all components, I may use SMD's.

My 3,3V on this

[Garth Wilson]

(09-27-2021 11:15 AM)toml_12953 Wrote:  and protect chips from the heat of soldering

Soldering heat will not damage the chips. I've seen chips actually running (not just in storage) at over 350°C (662°F), as I was looking at the actual bare die (ie, the actual silicon chip inside the IC) with an infrared microscope. I don't know how much over 350°C, because I was not allowed to get calibration data beyond that. They would not have lasted long going that hot, but it did not suddenly destroy them. The die will definitely not get anywhere near that hot when you solder one pin at a time by hand. When ICs are soldered by machine, whether wave-soldered, IR, whatever, the whole thing gets well above the melting point of the solder all at once, ie, all pins and the body too. I've been responsible for millions of ICs in our company over the years, and have never seen one fail from soldering heat.

Whether or not I use sockets in personal projects depends on several factors.

[toml_12953]

(09-27-2021 07:43 PM)Garth Wilson Wrote:  

(09-27-2021 11:15 AM)toml_12953 Wrote:  and protect chips from the heat of soldering

Soldering heat will not damage the chips. I've seen chips actually running (not just in storage) at over 350°C (662°F), as I was looking at the actual bare die (ie, the actual silicon chip inside the IC) with an infrared microscope. I don't know how much over 350°C, because I was not allowed to get calibration data beyond that. They would not have lasted long going that hot, but it did not suddenly destroy them. The die will definitely not get anywhere near that hot when you solder one pin at a time by hand. When ICs are soldered by machine, whether wave-soldered, IR, whatever, the whole thing gets well above the melting point of the solder all at once, ie, all pins and the body too. I've been responsible for millions of ICs in our company over the years, and have never seen one fail from soldering heat.

Whether or not I use sockets in personal projects depends on several factors.

Hey, that's good to know! I won't worry about it then. Thanks for the reply.

[Jim Horn]

Back in the early personal computer days (late 1970s), having every chip on a board socketed was the mark of a superior product as the chips were known to fail. As such, many things like my Apple ][ Plus had all 110 or so chips in sockets. Great!

But then, over time, the dissimilar metals of the socket contacts against the IC pins could slowly corrode or otherwise end up with intermittent contact. My Apple eventually degraded to a mean time between failures of under an hour. Only opening it and firmly pressing down on all 110 chips to reseat them would restore it to health. For a little while.

I was planning on desoldering all few thousand socket pins from the board and soldering the chips in directly while replacing many of them with lower power CMOS ones for reliability. Instead the whole thing was given away to someone who needed it.

Connectors are nature's way of making sure reliability doesn't get too high - and IC sockets are connectors... Good for chips that will need swapping (EPROMs and such), not so much otherwise.

[teenix]

(09-27-2021 07:46 PM)toml_12953 Wrote:  

(09-27-2021 07:43 PM)Garth Wilson Wrote:  Soldering heat will not damage the chips. I've seen chips actually running (not just in storage) at over 350°C (662°F), as I was looking at the actual bare die (ie, the actual silicon chip inside the IC) with an infrared microscope. I don't know how much over 350°C, because I was not allowed to get calibration data beyond that. They would not have lasted long going that hot, but it did not suddenly destroy them. The die will definitely not get anywhere near that hot when you solder one pin at a time by hand. When ICs are soldered by machine, whether wave-soldered, IR, whatever, the whole thing gets well above the melting point of the solder all at once, ie, all pins and the body too. I've been responsible for millions of ICs in our company over the years, and have never seen one fail from soldering heat.

Whether or not I use sockets in personal projects depends on several factors.

Hey, that's good to know! I won't worry about it then. Thanks for the reply.

More likely to damage the circuit board with excess heat.

cheers

Tony

[jjohnson873]

(09-27-2021 11:21 PM)teenix Wrote:  

(09-27-2021 07:46 PM)toml_12953 Wrote:  Hey, that's good to know! I won't worry about it then. Thanks for the reply.

More likely to damage the circuit board with excess heat.

cheers

Tony

Agreed. Desoldering can delaminate the copper from the pc board if all the solder isn't removed and forcing the integrated circuit out of the pcb holes or the surface mount fingers. A good hot air desoldering station and/or a vacuum desoldering gun is recommended
~ Jim J. ~

[Craig Bladow]

I lean towards using sockets if a board has DIP ICs on it. Having the ICs in sockets makes it a little easier to diagnose problems as it possible to quickly swap in known good parts or swap the same part from a different spot on the board and see if the problem moves.

[teenix]

That's the trouble with modern surface mount electronics, you can't swap IC's in and out of sockets anymore. Very hard to prototype too at the hobby level.

cheers

Tony

[Garth Wilson]

(09-28-2021 12:29 AM)jjohnson873 Wrote:  Desoldering can delaminate the copper from the pc board if all the solder isn't removed and forcing the integrated circuit out of the pcb holes or the surface mount fingers.

If the holes are plated through, the pads are like the flanges of a rivet, so delamination should not be a problem. It is very difficult to remove an IC from thru-plated holes though. The times I've needed to do this were always on cheap ICs where it was well worth it to sacrifice the IC to spare the board, so I'd cut all the pins, right at the body, then pull them out one by one, then clean up the holes. When the IC cost us 14 cents and the bare 12-layer board with no parts on it cost as much as $60, the decision is easy. I've had to do that when we were still using thru-hole, and to get maximum density, resistors and diodes went under the ICs, and manual stuffing led to the occasional error.

Now of course we're using SMT, and sometimes parts on both sides, and boards much smaller and less complex; so if the occasional repair needs a new IC, the whole board gets replaced. So far I have not heard of any IC failures on these though, and there certainly aren't any parts under the ICs to replace.

The only time I put DIPs on both sides, it was a small board with one IC (an EPROM) on the back, with a socket. The socket would be soldered in first, then they cut the rails holding the two sides together so they wouldn't be in the way of soldering the rows of pins coming through from ICs on the front. Without the socket, you'd have to apply the solder to that second side to the top of the pins. That would work in this case but it was an EPROM anyway which might need to be removed for reprogramming at some point.

[teenix]

(09-28-2021 04:32 AM)Garth Wilson Wrote:  If the holes are plated through, the pads are like the flanges of a rivet, so delamination should not be a problem. It is very difficult to remove an IC from thru-plated holes though.

Sometimes, especially on older boards, the actual via can stick to the IC pin and can pull out of the PCB hole. This is fixable though, just by soldering the new pin on both sides of the board.

I have an electric de-solder pump and before use I usually re-solder the joints (especially if old) to build up some solder on them. This allows better heat transfer for the de-solder iron and also helps to draw the solder from the PCB hole during suction.

A lot of times, the ICs are originally soldered such that the pins are pressing against the side of the via. Even after sucking out the molten solder, some stays and solidifies between the pin and via wall which is why they are hard to remove, or damaging to the PCB if you exert too much pressure trying to remove the stuck pin.

I take note of this and once the solder has melted, I use the soldering iron tip to push the pin sideways to the opposite side of the hole and then suck the solder out. Usually the pin will spring back a little and remain in the center of the hole without solder contact.

cheers

Tony