Failed Motorola 10261 ... transistor?

[eccerr0r]

I was looking through my junk pile and wanted to identify this TO-3 cased apparently transistor that's marked "M" and "10261".

From my googling around this may be a 2N3055 clone. I tested the B and E pins, and sure enough it seems like a normal B-E junction for a silicon NPN transistor.

However, I get no conductivity to the case at all (which is usually collector). While this probably means it's bad, this is a very strange failure mode as the collector is usually bonded to the flange on these devices and getting it to go open circuit is kind of tough (no die bonds to break.)

So, what is this device? (Trash, I think, but how could it fail in this way?)

This might end up getting the dremel treatment for curiosity...

[eccerr0r]

I was able to find another psu of the same type and used standard JEDEC numbering.

The 10261 is a 2n3055 and the 10262 was a 2n3773 in that photograph, so my hunch was correct that the 2n3055 was not a good sub for the 10262... And clearly the 10262 is NOT PNP!

The 2n3771 is also probably not a good fit due to low Vcemax. Hum.

Now, whether or not to buy (what? buy?) "new" (NOS?) transistors or not.

[stj]

Re: Failed Motorola 10261 ... transistor?

high current diode?
scr?

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

I think I ruled out a diode as usually one contact is the case.

SCR is possible, though explaining the E and B stamped into the flange needs explanation.

[budm]

Re: Failed Motorola 10261 ... transistor?

http://antiqueradios.com/forums/viewtopic.php?t=70011

Sounds like bad Transistor.

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

Yeah I'd have to agree at this point, though I'm not sure how this could have failed. It looks like I can pass a good 200-300mA just fine into the base-emitter (using my CCCV psu to test) but the collector remains open.

As the emitter and base have the weak die bonds, I'd suspect they to die first for an open. Then if a transistor is overheated, I'd imagine all the contacts to be shorted together. Weird, isn't it?

[jiroy]

Re: Failed Motorola 10261 ... transistor?

I Guess everything in the end has a life span . NTE equivalent is very good :

http://www.weisd.com/test/GenericPar...?editid1=10261

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

Fortunately it's a junk pile transistor, so I don't need to get a replacement for it.

I just find it very odd for it to fail this way. I thought transistors were grown from the substrate which forms the collector which is bonded to the flange (see the 2n3055 wikipedia page).

Unless the die isn't actually built this way and collector has a separate bonding pad...

[PeteS in CA]

Re: Failed Motorola 10261 ... transistor?

My guess is that "10261" is some major customer's in-house P/N. I think HP did that a lot. And it does sound like the C-B junction is blown open or the bond wires fused. Can-opener time!

[momaka]

Re: Failed Motorola 10261 ... transistor?

Well, since the B-E junction is still good, I suppose now you have a weak diode in a glorified TO-3 case.

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

or nothing, after my cutting blade slipped while trying to cut it open. I suppose I should have used metal fatigue to break the weld... oh well, nothing lost, well, maybe indeed a weak diode

BTW, yeah it used the apparently newer "little" small square die and bonding pad+whiskers instead of those beefy metal contacts in the wikipedia article. As I lost the actual die (it seemed to have gotten sheared off or something) I gained nothing. Oh well.

[goontron]

Re: Failed Motorola 10261 ... transistor?

http://antiqueradios.com/forums/viewtopic.php?t=70011

Sounds like bad Transistor.

Wooooa! Someone linking to ARF? Awesome!

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

After thinking about it a bit, maybe it didn't get sheared off and perhaps the die broke off from the setting, and that's why the collector went open... Hmm. Either case, the die is gone, not sure if it suffered grinding from the cutter or it fell out...

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

Just a stroke of ... luck? I found the remnants of the die.I don't think I have the pieces in the right place but that's the largest fragments I could find.

I wonder how tightly bonded the die is supposed to be with flange/substrate, though it does look like I had something to do with the fragmentation of the die.

[stj]

Re: Failed Motorola 10261 ... transistor?

earthquake - the fucking frackers broke your semiconductor!

[redwire]

Re: Failed Motorola 10261 ... transistor?

The die looks fine, not melted or burnt.
The die attach failed; I believe it can be epoxy or soldered for high-power parts.

Epoxy attach is on LED's and seems to be why they fail, they unglue off the substrate or a bond wire breaks.

eetimes Die bonding techniques and methods

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

Interesting, it looks like die bond/attach failures occur more often than I'd expect.

The bond wires look like 30AWG, though I wonder what material they are to be able to pass 15A (specifically the emitter wire)... It might be short enough it doesn't matter.

[PeteS in CA]

Re: Failed Motorola 10261 ... transistor?

I think the common bond wire material is aluminum. I wonder if the die-case connection was bad.

Back in ancient times when I opened "TO-3" cases (I think the modern case is TO-204), I used a hack saw very gently, barely breaking through the metal of the dome most of the way around.

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

Now what's the difference between TO-3 and TO-204, aluminum vs steel?

Pictured left to right:

2N3055 (aluminum TO-3?) (Silicon NPN)
2SC2930 (steel TO-204?) (Silicon NPN)
103-9 (steel TO-3?) (Germanium PNP)
2N1136A (aluminum flange, steel cap TO-204?) (Germanium PNP)
Guts of the 10261 (TO-3?) (Silicon NPN)

[budm]

Re: Failed Motorola 10261 ... transistor?

https://cdn.badcaps-static.com/pdfs/...3bfced6226.pdf
TO-204 is a newer case designation.

[eccerr0r]

Re: Failed Motorola 10261 ... transistor?

So they just labeled it TO-204 just "because," despite the fact they're identical?

looks like even the cap height has no bearing, and can be over a 0.1" higher and still be in tolerance...