Hi Phil,
I can't tell you if any of these are acceptable according to MIL standards,
but here are some sources for these components. Many of them are packaged
in molded or conformal coated packages rather than cans, so they are much
less prone to the catastrophes that traditional Alumin(i)um electrolytics
are. They have extremely long life at high temperatures (i.e. 20,000 hours
at 125 deg. C), stable ESR and capacitance with temperature and stable
capacitance with DC bias. If my applications could afford them, I'd use
them all over the place. Unfortunately in my commercial and medical work,
price usually takes precedence over elegance and long life.
Sanyo OS-CON
http://www.sanyo.com/industrial/components/oscon_home.html
Nichicon NA series
http://www.nichicon.co.jp/english/seihin/solid/pict_f.htm
Panasonic Specialty Polymer Al Capacitors
http://www.panasonic.com/industrial/components/specialty_polymer.htm
Mepco-Philips (now BC Components) Solid Al Capacitors
http://www.bccomponents.com/go/Products/index2.asp?Action=families&ExpandAct
ion=Expand&FamilyID=57&Indention=2
Regards,
Seth Goodman
Goodman Associates, LLC
tel 608.833.9933
fax 608.833.9966
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of DUTTON Phil
Sent: Thursday, April 04, 2002 6:32 PM
To: [log in to unmask]
Subject: Re: [TN] Aluminium Electrolytics
Thankyou Seth and Michael,
Certainly some good reasons not to use them in an airborne environment.
I've not heard of the Organic Polymer Aluminium electrolytics before.
Unfortunately, the mil std would still not allow their use.
We don't have a 2 cent coin anymore, only worth 1 US cent anyway. (our
lowest value coin is 5 cents)
regards,
Phil.
Phil Dutton C.I.D.
Senior CAD Technician
IPC Certified Interconnect Designer
Tenix Defence Pty Ltd
Electronic Systems Division
Second Avenue, Technology Park,
Mawson Lakes. SOUTH AUSTRALIA 5095
-----Original Message-----
From: Seth Goodman [mailto:[log in to unmask]]
Sent: Thursday, 4 April 2002 14:39
To: [log in to unmask]
Subject: Re: [TN] Aluminium Electrolytics
I also believe the ESR for standard aluminum electrolytics goes way up at
low temperatures. If there is substantial ripple current, as in a switching
power supply, the I squared R losses will cause the core to overheat,
spewing electrolyte and launching the can like a projectile. Quite
impressive the first time you see it (I highly recommend safety glasses).
Organic polymer Aluminum electrolytics are much better behaved at low and
high temperatures and have even lower ESR's so you often can use smaller
capacitors. In addition, they do not dry out, as all standard Aluminums
will (that's Aluminium for my Euro colleagues). They also happen to cost
three to ten times as much but they beat the heck out of tantalums for
equivalent price. My dos centavos, anyway.
This is OT, but what is the Euro equivalent of two cents? Is there a coin
for 1/100th of a Euro? If so do Europeans regard it with the same reverence
that we have for our pennies? For instance, many stores here have bowls on
the cash register where customers can leave their valuable pennies rather
than waste the effort of putting them into their pockets.
Regards,
Seth Goodman
Goodman Associates, LLC
tel 608.833.9933
fax 608.833.9966
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Wright, Michael D.
Sent: Wednesday, April 03, 2002 10:33 AM
To: [log in to unmask]
Subject: Re: [TN] Aluminium Electrolytics
Murata, at http://www.murata.com have a good article on this subject. Mainly
the reason is, that the aluminum electrolytic will loose 50% of the rated
capacitance a -40 degrees C. At -55C it is worse. This then also is true for
industrial applications. I just looked for the article that I am referring
to and couldn't find it, so I am attaching it.
Michael Wright
Sr. Engineer
ITT Cannon
952-974-5813
-----Original Message-----
From: DUTTON Phil [mailto:[log in to unmask]]
Sent: Tuesday, April 02, 2002 1:48 AM
To: [log in to unmask]
Subject: [TN] Aluminium Electrolytics
Hello Technetters,
Mil-STD-5400 para 4.3.8.2 says that aluminium electrolytic capacitors shall
not be used in airborne electronic equipment.
Can anyone please explain why this is so?
thanks,
Phil.
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