Hello folks

It`s the first time that I post into this forum. I`m a electronic newbie.

I found a lot of logic IC`s (74hex) and z80 cpu`s in the garbage. The components were wet from the rain. My questions:

Does water destroy ICs ?
Is it possible to test IC`s with a multimeter or a simple circuit like transistors or diodes, to make sure that they work?

Greetings Charon

 

most ICs would probably be fine if left to dry naturally. I wonder, though, why they were being thrown out in the first place...?

 

you would be surprized at what people throw out..
around here ..lately i've been seeing a lot of monitors ..ppl are buying LCD

 

I've worked for a couple of BIG companies, and the stuff they throw out would just make you cry. They order the wrong stuff, or too much of it, don't want to deal with it, so in the dumpster it goes.

Pure water shouldn't damage the stuff, as long as you let it air dry. In fact, if the water was perfectly pure (impossible) it wouldn't even hurt the stuff if it was energized, because perfectly pure water does not conduct.

j.

 

The IC won't be damaged by water.
The pins may start to rust though.

 

lol thats funny ...and sad..

 

Thanks for the feedback. It was helpful.

 

Electronic equipment, whether vacuum tube, solid-state (transistorized) or integrated circuit, used to be literally washed all the time to clean it up. Nary a problem if it is dried correctly -- low temp and a couple of days. Air drying your find is no problem.

However, I understand that the plastic (epoxy) IC packages cannot tolerate long term submergence of ICs in water or long term high humidity, while the ceramic MILSPEC packages can.

Dean

__________________
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

 

For years we used a dishwasher for finished circuit boards. No heat drying or soap, just water. It was the most efficient way to clean up water soluable fluxes and general dirt after hand soldering. The only thing we ever had to watch for was things like relays that water could get into and damage. To deal with that, we just used what are called "washable" parts... seriously... they have either a small sticker covering a vent hole, or in the case of DIP switches, peelable strip of rubbery adhesive that was removed after washing.

You are correct also about long term damage Dean, I have experienced this in automotive applications where the conformal coating has failed or was poorly applied ( most of the coatings now have a UV dye to make checking easier.) Mineral salts and metal oxides can migrate into the package and eventually destroy it. It takes along time to happen though.

 

I routinely wash pc boards to remove the dirt and "process residue" from them. I use water and scrub them with an old toothbrush using a small amount of dishwashing detergent. I rinse using water, then blow off the excess water using compressed air. I then thoroughly dry them using heatlamps before applying power. I'm very careful about the relays, transformers, open pots, etc. which could possibly suffer damage from getting wet. I've had no problems whatsoever using this method of cleaning. Of course, it only works if the contaminants are water soluble ...
JB

__________________
Nothing is impossible for the man who doesn't have to do it himself - Weiler's Law

 

Make sure they are really dry before soldering though. The water can crack the chip if its heated quickly.

 

contaminants in the water will dry up on the PCBs. so clean them with clean water, dry, and then power up

 

Years ago I had problem obtaining digital ICs so used to salvage
them from all kind of PCBs I could get my hands on (mostly obtained
from military scrap yard). Sometimes they ware covered in mud or
sand. Sometimes they were exposed to elements for long time
(more than one winter).

All I did was hose them down, desolder then throw all chips that
didn't have signs of damage into hot tub with some detergent to
remove remains of grease or whatever they ware in contact with.
Washed and dried and no problems... (well don't use boiling water,
just nice and warm to help remove contaminants).

Used or not, milspec chips are the best. Nowdays I use mostly
new stuff (when price is right). I don't like to buy stuff from surplus
stores because it's very often nothing but junk. Even if it's packaged
nicely it's the scrap that didn't make it to the market (wonder why...).

Bottom line is try and see for yourself. If something doesn't work,
it's not because of wash and dry process - it was dead before.