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Storing and using surface mount components.

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camerart

Active Member
Hi,
I am just making my first SMD PCB, and have received lots of components, and storage books.

The books have pages of plastic sheets, with many slots on each page. Some of the resistors are in anti-static bags, which got me to wondering if they can be stored in the books.

I've read that SMD components, are more susceptible to damage due to static, also humidity. This got me to thinking that perhaps the books should be stored in sealed bags with silica gel.

Any thoughts?
Camerart.
 

ronsimpson

Well-Known Member
Most Helpful Member
SMD components, are more susceptible to damage due to static
Why? I don't think so. In the case of ICs they have the same silicon inside.

I have more than one plan for SMD storage.
I get parts on tape.
If I am making a set of ten boards some time I use "part drawers". Then label the drawers "R1", R2", Q1, Q2, .....


I have these cabinets on the walls "100", "110", "120"......
DigiKey.com has a box with 100 of each common value. So I get a box for R0402 and a box of R0603, etc.
Some parts are in reals of 5000. I put them on a book shelf. Large resistors, small resistors, large caps, small caps, diodes, transistors, etc.

It is really important to find the part, with out hours of searching.
 

Colin

Active Member
Either use a set of drawers or get a stiff card and tape each strip of say 10 or 20 by the end of the strip and put the value on the card.
The card corresponds to the project. Label it.
I never use R1 etc. I only use actual values and this is especially important with capacitors.
To get what you want, peel back the tape with tweezers and use tweezers to fit the components with the marking upwards. Only expose one value at a time.
Fitting SMD is much faster than through-hole.
 

BobW

Active Member
The biggest concern for SMD parts is that there is a limited time span over which they can reliably be used in a high production environment. As soon as you open the package, the leads start to oxidize, making them progressively more difficult to solder as time goes by.

This isn't always made clear when you by cheap components like resistors and capacitors. But, when you buy expensive IC's, they are usually hermetically sealed in high grade packaging, and accompanied with a warning that you should use them quickly after opening the package, or else risk soldering problems.
 

robertpeng

New Member
Capacitors Standard Storage Conditions: temperature 5 ℃ ~ 35 ℃, humidity 35 to 70%. Generally six months to 1 year shelf life.

Resistors standard storage conditions: temperature 15 ℃ ~ 35 ℃, humidity 25% to 75%, generally 2 years shelf life.

Robert Peng- SysPCB
 

camerart

Active Member
Hi R, C, and B,
I have a new part rack screwed to the wall, which I will use for the 'fatter' comonents. For smaller ones, I bought books like this: http://www.ebay.co.uk/itm/292119051304?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT for my start in SMD PCBs, these of course are open to the elements (almost)
I also bought components for a particular project from Farnell, and as mentioned came in anti static sealed bags. This was what initiated the question, why?
I read a little about using SMDs and B has reminded me about the soldering problem. I have many old through the hole components, that I've had for a long time, and have to clean the legs before soldering.
I think I'll store the books in sealable bags with silica gel. Perhaps this is overkill, as I'm not in a production environment.
Thanks, C.
 

camerart

Active Member
Capacitors Standard Storage Conditions: temperature 5 ℃ ~ 35 ℃, humidity 35 to 70%. Generally six months to 1 year shelf life.

Resistors standard storage conditions: temperature 15 ℃ ~ 35 ℃, humidity 25% to 75%, generally 2 years shelf life.

Robert Peng- SysPCB
Hi R,
Ok, thanks. What is is it that deteriorates?
C.
 
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