Surface Mount Capacitors

[tt]

I was looking for replacements to recap an SE/30 motherboard, and noticed that Panasonic has announced new type (Conductive Polymer Hybrid Aluminum Electrolytic Capacitor) of electrolytic capacitors that are supposed to be longer-life and higher reliability due to a different design. They are not out on the market yet. There were some comments made in other threads about tantalum caps having the disadvantage of having catastrophic failures. Any thoughts out there?

http://industrial.panasonic.com/www-cgi/jvcr21pz.cgi?E+PZ+3+ABA0135+4++WW

Also, does anyone happen to have the physical dimensions in mm of the larger axial electrolytic capacitors?

[GnatGoSplat]

They are just a hybrid of conventional liquid electrolytics and polymer solid capacitors, so they're not exactly like a conventional "wet" capacitor and not exactly like a regular solid polymer capacitor. The reason it's hybrid is because solid polymer capacitors aren't available in higher voltage ranges. If you don't need really high voltages, a regular solid polymer would be better. I don't now how they compare to tantalum, but the solid polymer ones have been used in higher quality PC motherboards since around 2007.

[tt]

Seems like the hybrid and polymer type could be a direct replacement with the advantage of not leaking in the future and not having the catastrophic failure issue tantalum caps have.

[GnatGoSplat]

I agree, solid polymer capacitors are currently used in place of conventional electrolytics in almost all modern electronics where reliability and low ESR are important. The hybrid polymer will probably find its way in power supplies where higher voltage capacitors are required.

[tt]

This cap looks like a good replacement for the (10) 47uF caps on the SE/30 board: http://www.mouser.com/Search/ProductDet ... D470MCL1GS

I could not find a 1uF polymer cap anywhere, so I would use a tantalum cap.

[tt]

I recapped the logic board with the polymer caps and all went well. The board pretty much looks stock with the polymer cans.

Some notes about recapping:

If you see a recommendation to twist, pry or lift off caps, don't do it. Even though there was some evidence of corrosion on my board, the leads of the caps were still firmly attached.

I used the cutting method. Cut the cap with a side cutter near the bottom of the can, and either pull off the remains of the aluminum can or cut it again in between the leads. Then cut or gently pull off the rubber seal around the remaining leads and then try to crack off the plastic base by "folding" it in half along the axis of the two pins. I was then able to desolder each pin separately. No pads were lifted or over-stressed. I used some flux (in pen form) to help remove the more crusty stuff and also with soldering new components.

To solder on SMT aluminum cans, I pre-tinned the leads on the component and the pads on the board. Then I heated the protruding pad on the board to make the connection.

The job is somewhat difficult since the leads can be hard to remove due to oxidization and corrosion. It takes a bit of patience and having the right tools to do the job. If you don't have a lot of experience, it might be best to have someone help you out who has done it before.

[spiceyokooko]

I'm considering redoing the capacitors on my Mac IIci and Mac II boards which stubbornly refuse to boot regardless of what I do them.

I've looked at both boards and noted the locations and sizes of each of the capacitors that will need replacing.

What replacement for the 3 x 470uf and 1 x 200uf axial aluminium capacitors do you use? I presume the only option with these is to replace them with 'like for like', but what ESR and Ripple Current specifications do you select? I again assume the lowest ESR you can ideally get but are there optimums you shouldn't go above or below?

The 47uf and 10uf I assume are replaced with Surface Mounted polymer or tantalums? But again what ESR and Ripple Current specs do you look for? As I understand it (and I'm a newbie to electronic components) for motherboards the ideal is a low ESR and high Ripple Current, but what specification is considered low and high?

Cheers!

[tt]

The only metrics I considered were capacitance, voltage rating, and size (important especially for axials for this board in particular). Also reliability of the cap technology was a concern and would choose the higher reliability spec'd component even if it costs a bit more since I would rather not have to recap again. I haven't heard much brought-up about other electrical properties...

Here is what I ordered:

Axial, 470uF (higher temp rating): http://www.mouser.com/ProductDetail/Vis ... SsBw%3d%3d

Axial, 220uF: http://www.mouser.com/ProductDetail/Nic ... C7HYP2Y%3d

[trag]

I just wanted to mention that I have capacitors for the early Macs available:

http://68kmla.org/forums/viewtopic.php?f=4&t=16626

If you will have more fun sourcing them yourself, please do not let me discourage you, but if you don't want to hassle with finding replacements, it's pretty easy to order them from me.

[tt]

trag, it looks like you only stock tantalum surface mount caps. I started this thread to find alternatives to those (all components have pros/cons). Going this route is more expensive, but here are the parts (for SE/30) to order from Mouser if you are interested in the potential benefits discussed above:

(Qty 10) 47uF caps: http://www.mouser.com/Search/ProductDet ... D470MCL1GS
C6: http://www.mouser.com/Search/ProductDet ... 05K35TE5K0
C2: http://www.mouser.com/Search/ProductDet ... -118-35471
C11: http://www.mouser.com/Search/ProductDet ... VX1C221MAD

Note: I cannot find a polymer alternative for C6 at this time.