IC sockets - Page 1
Forum section: electronics / beginners

author: tobia
author_rank: Contributor
timestamp: May 26, 2015, 07:33:07 pm
content: When is it a good idea and/or essential to use a DIP socket for a chip?Alternatively, when is it acceptable to just solder the chip on the board? I couldn't find any past thread on the topic.I'm sure I've heard/read more than once to use sockets for older CMOS chips. Is it because they are easily damaged by ESD and so it's important to easily replace them? Or does the soldering heat actually damage the chip?Of course a valid reason to put microcontrollers and memories on sockets is to be able to reprogram them.What about optocouplers, 555, and other TTL chips? Can I solder them without a socket?

author: retrolefty
author_rank: Super Contributor
timestamp: May 26, 2015, 07:36:21 pm
content: IC sockets are not a requirement for most any chip. They do make sense for chips that might need changing before a device's end of life estimate. Like custom ROM chips holding firmware that might need to undergo an 'update'. The use of a socket on the standard arduino 328p boards made a lot of sense in that a beginner could replace the chip for $5 rather then have to buy a new board after some destructive learning experience.

author: lapm
author_rank: Frequent Contributor
timestamp: May 26, 2015, 08:05:26 pm
content: My personal rule on my own projects is to use sockets if i think i may later recycle those ic's from prototype to something else. Yep, some chips are just so cheap that socket is actually more expensive then ordering more chips.

author: Thor-Arne
author_rank: Unknown
timestamp: May 26, 2015, 09:35:35 pm
content: Sockets is also useful when prototyping as the IC can be replaced with little effort when something lets out the magic smoke or just for testing with another type of IC.I use sockets for everything when prototyping on prefboards.

author: SL4P
author_rank: Super Contributor
timestamp: May 26, 2015, 09:59:24 pm
content: Line interface drivers and transceiver chips.When you blow them up (lightning, surges etc) - pop the old one out and replace.Pretty standard in a lot of higher spec gear.

author: dacman
author_rank: Frequent Contributor
timestamp: May 27, 2015, 01:27:59 am
content: Sockets can also help avoid heat damage (to the IC).

author: rs20
author_rank: Super Contributor
timestamp: May 27, 2015, 01:32:48 am
content: Quote from: dacman on May 27, 2015, 01:27:59 amHeat damage due to soldering? That's a bit much, you have to be having a really bad time soldering if IC temperature is getting even close to the damage threshold.

author: dacman
author_rank: Frequent Contributor
timestamp: May 27, 2015, 02:37:34 am
content: Quote from: rs20 on May 27, 2015, 01:32:48 amI admit that heat damage is a stretch, but there are ICs with a soldering tolerance of 300 degrees Celsius for 10 seconds, and I usually set my iron for about 345 degrees.

author: retrolefty
author_rank: Super Contributor
timestamp: May 27, 2015, 02:39:57 am
content: Quote from: dacman on May 27, 2015, 02:37:34 amJust solder one pin at a time with enough cool down time before moving to another pin. Shouldn't take more then 2-3 seconds to solder a single IC pin.

author: rs20
author_rank: Super Contributor
timestamp: May 27, 2015, 02:49:49 am
content: Quote from: retrolefty on May 27, 2015, 02:39:57 am+1, +the fact that that rating is probably conservative, +the fact that the rating is surely referring to all pins at once (wave soldering/reflow soldering etc) or, the limit is reset when you move onto the next pin. I mean, if you solder one pin at a time, the other 7 legs are acting as heatsinks. Bottom line: if you're damaging ICs while soldering, you're doing somethingdramaticallyweird. If youthinkyou're approaching the datasheet limits, you've either misunderstood the limits, or you're indeed doing somethingdramaticallyweird. The cure here is vaguely acceptable soldering practice, not a socket prophylaxis.

author: SL4P
author_rank: Super Contributor
timestamp: May 27, 2015, 02:56:07 am
content: An interesting side topic...Even nowadays, sockets included, I tend to solder corner anchor pins, then diagonally one at a time to reduce thermal stress, (or melting the cheap sockets!)Just habit from the old days!!

author: dacman
author_rank: Frequent Contributor
timestamp: May 27, 2015, 03:44:26 am
content: I just read the datasheet for a CD4076 (CMOS) and it stated a lead temperature during soldering of 265 degrees C max for 10 seconds 1/16" from the case.Sockets make one form of troubleshooting easier (they allow ICs to be easily swapped with a known good unit) but they can also develop contact problems, which is more common than a bad IC, in my experience, especially if gold plated sockets are not used, although even they are not immune to contact problems.The statement about heat was based on a unit that I maintain several dozen of. It has over 100 ICs in sockets. One particular IC may or may not be in a socket, and in some units, it degrades over time, but seemingly only if it's not in a socket. Once I noticed that the circuit worked best in units that the IC was in a socket, and was only giving trouble in units that the IC was soldered in, I concluded that soldering heat may be detrimental to the performance of the IC causing it to degrade over time. (I’ve replaced a lot of those ICs and added a gold-plated socket for each.)

author: SL4P
author_rank: Super Contributor
timestamp: May 27, 2015, 03:50:06 am
content: Quote from: dacman on May 27, 2015, 03:44:26 amGood point.Thermal cycling in a workplace can cause all sorts of problems with socketed parts.Expansion, condensation and other gremlins.

author: dom0
author_rank: Super Contributor
timestamp: May 27, 2015, 06:44:53 am
content: Quote from: SL4P on May 26, 2015, 09:59:24 pmI repaired a piece of DMX-gear once and the manufacturer was so nice to print a list of compatible transceivers (by three sources or so) directly on the silkscreen. Neat!

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: May 27, 2015, 06:54:12 am
content: When I repair a device, I usually put sockets if I need to replace an IC.This for at least two reasons :- Its a pain to desolder ICs.- If an IC failed once, it may well fail another time. It may even fail immediately if the reason for the failure comes from something else.- I may not have the exact replacement IC and need to try a possible (even temporary) replacement.- I have a large, inherited from a friend, old stock of sockets.

author: G7PSK
author_rank: Super Contributor
timestamp: May 27, 2015, 07:10:13 am
content: When I solder DIP type IC's I use a bulldog type paper clip on the them as a heat sink. Chips like 555 and other really cheap chips I always solder straight onto or into the board,even if it just a trial.

author: tobia
author_rank: Contributor
timestamp: May 27, 2015, 10:41:18 pm
content: Thank you for all the good pointers, really gave me a feeling for when and why to use sockets.