[sdiy] advice please -- aging chips and caps

Czech Martin Martin.Czech at micronas.com
Mon Aug 11 09:58:04 CEST 2003


Yes.

Except maybe very old chips from the dawn of CMOS integration,
where the Al recepy was not so good. Since at least 1980
mixtures of Al-Si-Cu
are used, also to make migration less probable.

Temperature has a very large influence.

An example process has the following data:

     T   80C 100C 125C
Jmax     2   1    0.5       mA/um

(the semiconductor guys think 2D, so that's why mA/um and not mA/um^2


It is not likely that the synth is running at Tj=125C all day long.
Yes , a mains switch for all the gear in your studio, and another set of switches
to power unly the used gear is a good thing to have.


m.c.

-----Original Message-----
From: James Patchell [mailto:patchell at cox.net]
Sent: Samstag, 9. August 2003 23:30
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] advice please -- aging chips and caps


Personally, I wouldn't worry about the IC's.  Especially, the 4000 
series.  By todays standards, the 4000 series is a very crude IC (large 
features).  I have no idea what process is used to make them now, or even 
then, but somehow I just don't seem to think of metal migration and 4000 
series in the same thought (I could be wrong).

         My understanding of metal migration is that you need a high 
current density flowing through the conductor (how high?? don't know) to 
make this happen.  Since the 4000 series is both crude and low current, I 
would put this at the bottom of things to worry about...

         I would be more inclined to worry about certain vendors parts (as 
was discussed a couple of months ago)...

         -Jim

At 10:33 AM 8/9/2003 -0800, Scott Gravenhorst wrote:
>I thought the same thing...
>
>Actually, the URL supplied is rather interesting.  I didn't know
>about "metal migration".
>
>Are recently manufactured ICs still subject to this?  If the old
>ones only last 15 years (expected life), then what of new ones?
>  I'd prefer that they outlast *me*.  This is pertinent for me
>because I have a 4000 series fetish.
>
>I'm all ears... er eyes...
>
>Tim Ressel <madhun2001 at yahoo.com> wrote:
> >John,
> >
> >I'd replace all the electrolytics.
> >
> >Replace the 4000's??? I've never heard of that. The
> >only thing I can think of is if the ICs were stressed
> >by ESD hits. I'd leave them until something fails.
> >
> >--tr
> >
> >
> >--- john mahoney <jmahoney at gate.net> wrote:
> >> Having read Scott Rider's article "Things to Know
> >> When Repairing Vintage
> >> Synthesizers"
> >> (http://www.oldcrows.net/~oldcrow/synth/tips.txt), I
> >> am now a
> >> little concerned about my Korg Mono/Poly, which has
> >> reached adulthood
> >> (assuming that synth years = human years).
> >> Basically, Scott says to replace
> >> all old 4000 series CMOS chips as well as certain
> >> types of caps.
> >>
> >> My questions for you folks:
> >> (1) Many of you have years of experience. Have you
> >> seen signs of CMOS
> >> senility or caps with Alzheimer's?
> >> (2) Should I replace the "at risk" components now,
> >> even though the synth is
> >> working perfectly? Or, wait and see, but *if*
> >> something goes bad then
> >> replace everything as he suggests. I'd like to add a
> >> few extra
> >> inputs/outputs/patchpoints to the Korg, so I have
> >> reason to do surgery.
> >> (See? This is a DIY question!)
> >> (3) Given the parts list below, do you see any parts
> >> that I should try to
> >> obtain now, just in case? For example, if the SSM
> >> chips are available,
> >> should I stock some? (I don't even know if the SSM
> >> chips are available
> >> anymore!)
> >> (4) Oh, yeah: What's the difference between the
> >> HD14000 series and the
> >> normal 4000 series, if any?
> >>
> >> ICs in the Mono/Poly (thanks to the excellent Zen
> >> Mono/Poly website):
> >>     SSM2044 4-pole voltage controlled filter
> >>     SSM2033 Voltage controlled oscillator (Qty: 4)
> >>     MM5837 Digital noise source
> >>     Intel 8049 8mhz CPU
> >>     HD14007UBP Dual complementary pair + inverter
> >>     HD14013BP Dual D flip-flop
> >>     HD14042BP Quad latch
> >>     HD14066BP Analog CMOS switch
> >>     HD14069UBP Hex inverter
> >>     HD14071 Quad "or" gate
> >>     HD14174BP Hex flip-flop
> >>     MC14504 Hex level shifter
> >>     NJM4556 Dual high-current op-amp
> >>     NJM4558DV Dual op-amp
> >>     M5230L Variable output voltage regulator
> >>     TL072 Dual J-FET operational amplifier
> >>
> >> Thanks to everyone for any and all insight you can
> >> offer.
> >> --
> >> john
> >>
> >
> >
> >__________________________________
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> >
>
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