BJT's Moisture Sensitive Devices storage?

H

Hammy

Guest
I just bought some BJT's OnSemi's low Vcesat high gain NJT4031NT1G and
complementary NJT4030PT1G.

NJT4031NT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4031N.PDF

NJT4030PT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4030P-D.PDF

They came with an advisement "Caution this bag contains Moisture
Sensitive Devices" Level #3

Where level 3 is

"floor life out of bag"
168 hours <30 C/60% RH

Does this mean that these BJT's would only last 168 hours shelf life
when taken out of the bag? This doesn't make any sense what if you use
these in a circuit that only see's intermittent use will the BJT specs
deteriorate?

I have no immediate need for these I just got them to test them out
switching speed,vcesat and gain.

I usually store my smd components rewraped in antistatic bags and
labeled in coin envolopes. I dont revacum seal them though. Would this
method still work for components with Moisture warnings?
 
On Wed, 31 Dec 2008 16:47:04 -0500, Hammy <spamme@hotmail.com> wrote:

I just bought some BJT's OnSemi's low Vcesat high gain NJT4031NT1G and
complementary NJT4030PT1G.

NJT4031NT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4031N.PDF

NJT4030PT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4030P-D.PDF

They came with an advisement "Caution this bag contains Moisture
Sensitive Devices" Level #3

Where level 3 is

"floor life out of bag"
168 hours <30 C/60% RH

Does this mean that these BJT's would only last 168 hours shelf life
when taken out of the bag? This doesn't make any sense what if you use
these in a circuit that only see's intermittent use will the BJT specs
deteriorate?

I have no immediate need for these I just got them to test them out
switching speed,vcesat and gain.

I usually store my smd components rewraped in antistatic bags and
labeled in coin envolopes. I dont revacum seal them though. Would this
method still work for components with Moisture warnings?
Click to expand...
That limit is "time to reflow." If you do reflow them, you should bake
them at the recommended temperature profile to drive out moisture before
subjecting them to reflow temps. Good dope at:
http://www.intel.com/design/packtech/ch_08.pdf

--
Rich Webb Norfolk, VA
 
On Wed, 31 Dec 2008 16:47:04 -0500, Hammy <spamme@hotmail.com> wrote:

I just bought some BJT's OnSemi's low Vcesat high gain NJT4031NT1G and
complementary NJT4030PT1G.

NJT4031NT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4031N.PDF

NJT4030PT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4030P-D.PDF

They came with an advisement "Caution this bag contains Moisture
Sensitive Devices" Level #3

Where level 3 is

"floor life out of bag"
168 hours <30 C/60% RH

Does this mean that these BJT's would only last 168 hours shelf life
when taken out of the bag? This doesn't make any sense what if you use
these in a circuit that only see's intermittent use will the BJT specs
deteriorate?

I have no immediate need for these I just got them to test them out
switching speed,vcesat and gain.

I usually store my smd components rewraped in antistatic bags and
labeled in coin envolopes. I dont revacum seal them though. Would this
method still work for components with Moisture warnings?
Click to expand...
Theoretically, a surface-mount device can absorb moisture and crack
when reflow soldered, so they want them kepy dry until then. I've
never seen it happen.

They'll last about forever once on a board.

John
 
On Wed, 31 Dec 2008 15:29:40 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


Theoretically, a surface-mount device can absorb moisture and crack
when reflow soldered, so they want them kepy dry until then. I've
never seen it happen.

They'll last about forever once on a board.

John
Click to expand...
Thanks I didn't want to ruin them; I've also gotten some other
components with similar warnings. I guess since I solder by hand it's
not a problem.

Did you see the specs on these fig. 6 (NJT4031NT1G Data sheet) Vce sat
of less then 300mV for 3A of collector current with only 25mA base
drive. Perfect for direct drive off a uC or a cheap 3A push-pull Fet
driver. I know zetex makes good ones also but they are pretty pricey
these only cost 0.30 cents each cut tape. Why so cheap what am I
missing?
 
"Hammy"

Did you see the specs on these fig. 6 (NJT4031NT1G Data sheet) Vce sat
of less then 300mV for 3A of collector current with only 25mA base
drive. Perfect for direct drive off a uC or a cheap 3A push-pull Fet
driver. I know zetex makes good ones also but they are pretty pricey
these only cost 0.30 cents each cut tape. Why so cheap what am I
missing?
Click to expand...

** A couple of things - you have equated the "typical" performance data
curves with guaranteed minimis and ignored the heat dissipation problems of
such a small package.

A worst case (ie low Hfe) sample might well take several times your 25mA
figure for the same Vce at 3 amps PLUS the dissipation in any case will be
almost 1 watt.

Read carefully what the data has to say about this and note that even with a
1 sq inch of copper area acting as a heatsink, the temp rise above the local
ambient of the chip is 64 degrees C for each watt.



...... Phil
 
On Thu, 1 Jan 2009 13:15:58 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:


** A couple of things - you have equated the "typical" performance data
curves with guaranteed minimis and ignored the heat dissipation problems of
such a small package.

A worst case (ie low Hfe) sample might well take several times your 25mA
figure for the same Vce at 3 amps PLUS the dissipation in any case will be
almost 1 watt.

Read carefully what the data has to say about this and note that even with a
1 sq inch of copper area acting as a heatsink, the temp rise above the local
ambient of the chip is 64 degrees C for each watt.



..... Phil

Figures it was too good to be true.
Click to expand...

I did hook one up driving it off a 556 timer at 144kHz 58% duty and it
is reasonably fast at turn-on but the turn off leaves a bit to be
desired it takes about 1.4uS to turn-off!

For 1.2A collector pulses it was giving 0.08V collector emitter with
about 10mA at the base driven from the 556.
 
On 2009-01-01, Hammy <spamme@hotmail.com> wrote:

I did hook one up driving it off a 556 timer at 144kHz 58% duty and it
is reasonably fast at turn-on but the turn off leaves a bit to be
desired it takes about 1.4uS to turn-off!

For 1.2A collector pulses it was giving 0.08V collector emitter with
about 10mA at the base driven from the 556.
Click to expand...
bypass some of the base resistor with a capacitor.
that'll suck charge off the base causing faster turn-off.
 
On Wed, 31 Dec 2008 16:47:04 -0500, Hammy <spamme@hotmail.com> wrote:

I just bought some BJT's OnSemi's low Vcesat high gain NJT4031NT1G and
complementary NJT4030PT1G.

NJT4031NT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4031N.PDF

NJT4030PT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4030P-D.PDF

They came with an advisement "Caution this bag contains Moisture
Sensitive Devices" Level #3

Where level 3 is

"floor life out of bag"
168 hours <30 C/60% RH
Click to expand...
---
Was there a desiccant in the bag?

JF
 
On Thu, 01 Jan 2009 07:54:32 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Wed, 31 Dec 2008 16:47:04 -0500, Hammy <spamme@hotmail.com> wrote:

I just bought some BJT's OnSemi's low Vcesat high gain NJT4031NT1G and
complementary NJT4030PT1G.

NJT4031NT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4031N.PDF

NJT4030PT1G Data sheet

http://www.onsemi.com/pub/Collateral/NJT4030P-D.PDF

They came with an advisement "Caution this bag contains Moisture
Sensitive Devices" Level #3

Where level 3 is

"floor life out of bag"
168 hours <30 C/60% RH

---
Was there a desiccant in the bag?

JF
Yes there is.
Click to expand...

I just took one out and used my vacum sealer to reseal them,leaving
the desiccant in there.

I also got some NCP1203 Controllers they also came with a similiar
warning. But the FMMT618 and FMMT617 didnt come with the mousture
warning.

Is this a concern with all SMD or just some ?

I handsolder so I dont think I really have to worry about heating one
enough to crack it or should I ?
 
Jasen Betts wrote:
On 2009-01-01, Hammy <spamme@hotmail.com> wrote:


I did hook one up driving it off a 556 timer at 144kHz 58% duty and it
is reasonably fast at turn-on but the turn off leaves a bit to be
desired it takes about 1.4uS to turn-off!

For 1.2A collector pulses it was giving 0.08V collector emitter with
about 10mA at the base driven from the 556.


bypass some of the base resistor with a capacitor.
that'll suck charge off the base causing faster turn-off.

I find the Vce(Sat) figure given (0.08) hard to grasp for
Click to expand...
that component. Maybe some capacitance/Inductance in the transient
cycle causing that reading to be low. I bet when the BJ was turned off
there was a small arch Peak on the high side.

http://webpages.charter.net/jamie_5"
 
On 1 Jan 2009 13:35:36 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:


bypass some of the base resistor with a capacitor.
that'll suck charge off the base causing faster turn-off.
Click to expand...
Yes I've been doing some reading thats what I'll try next.A Baker
clamp defeats the purpose of a low Vcesat BJT but I've found a few
things to try.

If I can get good transtions to about 100kHz I'll be happy,thats the
typical maximum switching speed I usually wind up with.

They are reasonable priced so even if I have to spend another 5 or 10
cents on a driver cct it's worth it.Even at the worst case Vce
sat(0.3V) and hfe (100) for 3A.
 
On Thu, 01 Jan 2009 10:00:33 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


I find the Vce(Sat) figure given (0.08) hard to grasp for
that component.
Click to expand...
Your probably right I just read the measurment my scope spat out. I
get more accuarate readings when zooming in but 0.1V is probably more
likely given the max they spec 0.150V. I'll find out for sure when I
do it again.

Maybe some capacitance/Inductance in the transient
cycle causing that reading to be low. I bet when the BJ was turned off
there was a small arch Peak on the high side.

http://webpages.charter.net/jamie_5"
Click to expand...
 
On Thu, 01 Jan 2009 10:00:33 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


I find the Vce(Sat) figure given (0.08) hard to grasp for
that component. Maybe some capacitance/Inductance in the transient
cycle causing that reading to be low. I bet when the BJ was turned off
there was a small arch Peak on the high side.

http://webpages.charter.net/jamie_5"
Click to expand...
More accurate measurements;

Vbe = 0.92V

556 Vout = 8.9V (The timer is supplied with 12V.)

I have a 1.2k 1% metal film resistor between the timer and the base.
So the base is getting 6.67mA.

Zooming right up gives a Vcesat of 182mV. Still pretty respectable for
only 6.67mA of base current.

To answer your next question yes there is a one volt pp ripple on the
12V rail but I'm using a 470uF polymer cap right by the load the over
and undershoot are essentially brief spikes so the collector current
is 1.2A. The load is two 5R 5W resistors 5% so maybe worst case 1.1A.
 
Hammy wrote:

On Thu, 01 Jan 2009 10:00:33 -0500, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:



I find the Vce(Sat) figure given (0.08) hard to grasp for
that component. Maybe some capacitance/Inductance in the transient
cycle causing that reading to be low. I bet when the BJ was turned off
there was a small arch Peak on the high side.

http://webpages.charter.net/jamie_5"


More accurate measurements;

Vbe = 0.92V

556 Vout = 8.9V (The timer is supplied with 12V.)

I have a 1.2k 1% metal film resistor between the timer and the base.
So the base is getting 6.67mA.

Zooming right up gives a Vcesat of 182mV. Still pretty respectable for
only 6.67mA of base current.

To answer your next question yes there is a one volt pp ripple on the
12V rail but I'm using a 470uF polymer cap right by the load the over
and undershoot are essentially brief spikes so the collector current
is 1.2A. The load is two 5R 5W resistors 5% so maybe worst case 1.1A.
Click to expand...
That's more realistic :)

One thing you may want to take into consideration is, BTJ's tend to
loss their Beta/Hfe gain when operating in cold environments.

To test this, I've sprayed BTJs with component cooler and then take a
few readings. This could lead you into changing the bias resistor to a
slightly lower value to accommodate for this.

Happy New Year..

http://webpages.charter.net/jamie_5"
 
Hammy wrote:

"Phil Allison" <philallison@tpg.com.au> wrote:

** A couple of things - you have equated the "typical" performance data
curves with guaranteed minimis and ignored the heat dissipation problems of
such a small package.

A worst case (ie low Hfe) sample might well take several times your 25mA
figure for the same Vce at 3 amps PLUS the dissipation in any case will be
almost 1 watt.

Read carefully what the data has to say about this and note that even with a
1 sq inch of copper area acting as a heatsink, the temp rise above the local
ambient of the chip is 64 degrees C for each watt.

Figures it was too good to be true.
Click to expand...
Practical example. A Chinese company did a partial ODM designed product for us. I
refined it. They'd used some SOT 23 devices, MMBT3904 and complement IIRC as FET
gate drivers. We had two explode on test.

In went the 2N3904 and its complement.

Graham
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top