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From: E on 9 Apr 2010 15:27
Just measured hfe from some BC337-40 at about 5 mA collector current.
Unfortunately nothing very interesting there

Results:
Sample size: 960 pcs
minimum hfe: 388
maximum hfe 513
(datasheet limits are 250 and 630)
avarage: 452
avarage deviation: 27
median: 463
mode: 477
Distribution is a bit strange looking with two spikes
Histogram here: http://koti.mbnet.fi/hsahko/hfe/

-ek


From: Joel Koltner on 9 Apr 2010 15:37
"E" <invalid(a)invalid.invalid> wrote in message
news:hpnv2c$5it$1(a)news.eternal-september.org...
> Distribution is a bit strange looking with two spikes

Maybe two different batches of parts?

From: E on 9 Apr 2010 15:58

"Joel Koltner" <zapwireDASHgroups(a)yahoo.com> kirjoitti
viestiss�:fmLvn.199280$rq1.66072(a)en-nntp-02.dc1.easynews.com...
> "E" <invalid(a)invalid.invalid> wrote in message
> news:hpnv2c$5it$1(a)news.eternal-september.org...
>> Distribution is a bit strange looking with two spikes
>
> Maybe two different batches of parts?
>

Possibly, alltought they were all from same bag.
Or maybe just from different wafers?
How many BC337 fit one wafer? Probably quite many...

-ek


From: John Devereux on 9 Apr 2010 16:25
"E" <invalid(a)invalid.invalid> writes:

> "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> kirjoitti
> viestissä:fmLvn.199280$rq1.66072(a)en-nntp-02.dc1.easynews.com...
>> "E" <invalid(a)invalid.invalid> wrote in message
>> news:hpnv2c$5it$1(a)news.eternal-september.org...
>>> Distribution is a bit strange looking with two spikes
>>
>> Maybe two different batches of parts?
>>
>
> Possibly, alltought they were all from same bag.
> Or maybe just from different wafers?
> How many BC337 fit one wafer? Probably quite many...
>
> -ek
>
>

Perhaps they take all the middle ones for a tighter-spec version?



--

John Devereux
From: Jim Thompson on 9 Apr 2010 16:37
On Fri, 09 Apr 2010 21:25:45 +0100, John Devereux
<john(a)devereux.me.uk> wrote:

>"E" <invalid(a)invalid.invalid> writes:
>
>> "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> kirjoitti
>> viestiss�:fmLvn.199280$rq1.66072(a)en-nntp-02.dc1.easynews.com...
>>> "E" <invalid(a)invalid.invalid> wrote in message
>>> news:hpnv2c$5it$1(a)news.eternal-september.org...
>>>> Distribution is a bit strange looking with two spikes
>>>
>>> Maybe two different batches of parts?
>>>
>>
>> Possibly, alltought they were all from same bag.
>> Or maybe just from different wafers?
>> How many BC337 fit one wafer? Probably quite many...
>>
>> -ek
>>
>>
>
>Perhaps they take all the middle ones for a tighter-spec version?

Roughly 80K _untested_ die (if wafer is 8"). The wafer is probably
auto-probed and binned into various device numbers.

Discrete device production is so automated... it's fascinating to
watch the automated handling equipment :-)

...Jim Thompson
--
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| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

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