Post by thread:My PIC is dead. 29.4.99 RIP

Sadly, my IND TEMP SMT 12c508 died this after noon, when I shot it with Freeze 75 thermal spray. This stuff claims to go down to -49degC, but the PIC was sitting in the sunshine when it got hit, so I expected it not to go lower than -40. I was very sad it DIED - I thought it might freeze until warmed up a bit, but now certified dead and in the WPB. Unfortunately I don't have a -40 thermometer. Should it have died, or just frozen up until warmed up or reset. ANyone any idea on PIC response outside certified range? Stuart Meier

Thermal shock could have killed it. Stuart Meier wrote: > > Sadly, my IND TEMP SMT 12c508 died this after noon, when I shot it with > Freeze 75 thermal spray. This stuff claims to go down to -49degC, but the > PIC was sitting in the sunshine when it got hit, so I expected it not to go > lower than -40. I was very sad it DIED - I thought it might freeze until > warmed up a bit, but now certified dead and in the WPB. > > Unfortunately I don't have a -40 thermometer. > > Should it have died, or just frozen up until warmed up or reset. ANyone any > idea on PIC response outside certified range? > > Stuart Meier

Yep, sounds like thermal shock.... your PIC in the sunshine was probably sitting around 120F or so then you hit the poor little guy with -40 degree freon, instantly shrinking the little wire interconnects, the die, everything. Chances are you snapped the little wires from the die to the pins. --- Kevin Fisk <spam_OUTkfiskTakeThisOuTWKPOWERLINK.COM> wrote: {Quote hidden}> Thermal shock could have killed it. > > Stuart Meier wrote: > > > > Sadly, my IND TEMP SMT 12c508 died this after > noon, when I shot it with > > Freeze 75 thermal spray. This stuff claims to go > down to -49degC, but the > > PIC was sitting in the sunshine when it got hit, > so I expected it not to go > > lower than -40. I was very sad it DIED - I thought > it might freeze until > > warmed up a bit, but now certified dead and in the > WPB. > > > > Unfortunately I don't have a -40 thermometer. > > > > Should it have died, or just frozen up until > warmed up or reset. ANyone any > > idea on PIC response outside certified range? > > > > Stuart Meier > _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

Stuart, I use extended rated pics there is E letter on it up to 125C in our dino we ran a test up to 140C it was still working fine sorry I didn't try cold test but this test tells me that microchip products are very reliable and you can trust them. I personally do. I like to know what temp range pic did you test.? Andre Stuart Meier wrote: {Quote hidden}> Sadly, my IND TEMP SMT 12c508 died this after noon, when I shot it with > Freeze 75 thermal spray. This stuff claims to go down to -49degC, but the > PIC was sitting in the sunshine when it got hit, so I expected it not to go > lower than -40. I was very sad it DIED - I thought it might freeze until > warmed up a bit, but now certified dead and in the WPB. > > Unfortunately I don't have a -40 thermometer. > > Should it have died, or just frozen up until warmed up or reset. ANyone any > idea on PIC response outside certified range? > > Stuart Meier

Stuart, What killed the PIC is not the temperature that you took it to, but the RATE OF CHANGE of temperature. Within a fraction of a second you took it from something substantially above 20 deg C to something below 40 deg C. With that large a RATE of change the innards of the PIC could well have been damaged by thermal shock. What you did was the equivalent of hitting the insides of the PIC with a sledge hammer. Always reduce the temperature SLOWLY. Don't just sneak up on the poor PIC and blast it with a super-cold spray. Apply the spray at first from a distance, and then slowly come closer so the chip has a chance to cool at a relatively slow rate. When attempting to actually RUN a frozen chip, be aware that the onlsought of current coursing through the chip can cause local heating that can ALSO cause a local thermal shock. You will have various temperature gradients present, and even if the chip works, it may appear flakey until the over-all chip temperature stabilizes. Fr. Tom McGahee ---------- {Quote hidden}> From: Stuart Meier <.....smeierKILLspam@spam@PAVILION.CO.UK> > To: PICLISTKILLspamMITVMA.MIT.EDU > Subject: My PIC is dead. 29.4.99 RIP > Date: Thursday, April 29, 1999 1:21 PM > > Sadly, my IND TEMP SMT 12c508 died this after noon, when I shot it with > Freeze 75 thermal spray. This stuff claims to go down to -49degC, but the > PIC was sitting in the sunshine when it got hit, so I expected it not to go > lower than -40. I was very sad it DIED - I thought it might freeze until > warmed up a bit, but now certified dead and in the WPB. > > Unfortunately I don't have a -40 thermometer. > > Should it have died, or just frozen up until warmed up or reset. ANyone any > idea on PIC response outside certified range? > > Stuart Meier

It could have been condensation shorting the pins as well as thermal shock. -----Original Message----- From: Stuart Meier [.....smeierKILLspam.....PAVILION.CO.UK] Sent: Thursday, April 29, 1999 10:21 AM To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU Subject: My PIC is dead. 29.4.99 RIP Sadly, my IND TEMP SMT 12c508 died this after noon, when I shot it with Freeze 75 thermal spray. This stuff claims to go down to -49degC, but the PIC was sitting in the sunshine when it got hit, so I expected it not to go lower than -40. I was very sad it DIED - I thought it might freeze until warmed up a bit, but now certified dead and in the WPB. Unfortunately I don't have a -40 thermometer. Should it have died, or just frozen up until warmed up or reset. ANyone any idea on PIC response outside certified range? Stuart Meier

Thanks for all the responses. I should have thought of thermal shock, and condensation. He seemed fine all covered in snow, death was during the warm up it appeared (either because of lag as the core of the PIC caught up with external temp, or the snow melting...) So next time I shoot him with Freon I will give him warning, and do it v----e----r----y s---l----o----w----l----y! Stuart Meier -----Original Message----- From: Thomas McGahee <tom_mcgaheespam_OUTSIGMAIS.COM> To: @spam@PICLISTKILLspamMITVMA.MIT.EDU <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> Date: 29 April 1999 19:25 Subject: Re: My PIC is dead. 29.4.99 RIP >Stuart, >What killed the PIC is not the temperature that you took it to, >but the RATE OF CHANGE of temperature. Within a fraction of a second

I'm sitting in my chair cracking up the way you guys refer to PICs as "beings." We should start a list..."You know you've been using PICs too long when..." <VBG> btw, when are the funeral services? Tim H. In a message dated 4/29/99 3:02:02 PM Pacific Daylight Time, RemoveMEsmeierTakeThisOuTPAVILION.CO.UK writes: {Quote hidden}> Thanks for all the responses. I should have thought of thermal shock, and > condensation. He seemed fine all covered in snow, death was during the warm > up it appeared (either because of lag as the core of the PIC caught up with > external temp, or the snow melting...) > > So next time I shoot him with Freon I will give him warning, and do it > v----e----r----y s---l----o----w----l----y! > > Stuart Meier >

In message <012501be928b$c2427fc0$1d084ad4@StuartMeier>, Stuart Meier <spamBeGonesmeierspamBeGonePAVILION.CO.UK> writes >Thanks for all the responses. I should have thought of thermal shock, and >condensation. He seemed fine all covered in snow, death was during the warm >up it appeared (either because of lag as the core of the PIC caught up with >external temp, or the snow melting...) I would suspect the chip must have been faulty to have died in this way, I've been squirting chips with freezer for years (while looking for thermal intermittent faults), and good chips don't have any problems with been turned into an iceberg :-). -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : TakeThisOuTnigelgEraseMEspam_OUTlpilsley.demon.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | | Chesterfield | Official site for Shin Ki and New Spirit | | England | Ju Jitsu | \--------------------------------------------------------------/

I agree, the chip might be defective. Where I used to work(we made DRAM's), packaged chips were subjected to much more severe thermal shock than what you had described. When we had failures, we normally traced it back to either fabrication or packaging problems. Regards, Bancherd(Mike) DeLong Nigel Goodwin wrote: {Quote hidden}> In message <012501be928b$c2427fc0$1d084ad4@StuartMeier>, Stuart Meier > <RemoveMEsmeierTakeThisOuTPAVILION.CO.UK> writes > >Thanks for all the responses. I should have thought of thermal shock, and > >condensation. He seemed fine all covered in snow, death was during the warm > >up it appeared (either because of lag as the core of the PIC caught up with > >external temp, or the snow melting...) > > I would suspect the chip must have been faulty to have died in this way, > I've been squirting chips with freezer for years (while looking for > thermal intermittent faults), and good chips don't have any problems > with been turned into an iceberg :-). > -- > > Nigel. > > /--------------------------------------------------------------\ > | Nigel Goodwin | Internet : nigelgEraseME.....lpilsley.demon.co.uk | > | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | > | Chesterfield | Official site for Shin Ki and New Spirit | > | England | Ju Jitsu | > \--------------------------------------------------------------/