Science and Technology news... :: View topic - 0805 size high power resistors, 250mW ok on FR-4?

Joerg · Guest

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

John Larkin · Guest

On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

[quote]Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?
[/quote]
Sounds OK to me. We push regular 0805>s harder than that. Zero fails
so far.

We experimented with various resistors, 0603 through 1206, with a
thermal imager that has plenty of resolution to find the hot-spot temp
on all the parts.

Turns out that the actual part thetas are astronomical, and what cools
resistors is the copper pads and traces, more than the bodies
themselves. An 0603 soldered to big copper pours can dissipate as much
as a 1206 ditto; the hot spot temps are the same. That makes sense
physically, as theta is determined by the L/W ratio and the substrate
thickness, and all the resistors we checked were all 20 mil thick
alumina.

A better substrate, BeO or AlN, would help a bit, at great expense.

If there>s a ground plane close, that helps a lot.

The easiest thing to do is fire up the board and scope it with a Flir,
and see how hot stuff gets. You can borrow mine, or come here and use
it.

ftp://66.117.156.8/IR_0026.jpg

ftp://66.117.156.8/IR_0032.jpg

John

Joerg · Guest

John Larkin wrote:
[quote]On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Sounds OK to me. We push regular 0805>s harder than that. Zero fails
so far.

We experimented with various resistors, 0603 through 1206, with a
thermal imager that has plenty of resolution to find the hot-spot temp
on all the parts.

Turns out that the actual part thetas are astronomical, and what cools
resistors is the copper pads and traces, more than the bodies
themselves. An 0603 soldered to big copper pours can dissipate as much
as a 1206 ditto; the hot spot temps are the same. That makes sense
physically, as theta is determined by the L/W ratio and the substrate
thickness, and all the resistors we checked were all 20 mil thick
alumina.

A better substrate, BeO or AlN, would help a bit, at great expense.

If there>s a ground plane close, that helps a lot.

The easiest thing to do is fire up the board and scope it with a Flir,
and see how hot stuff gets. You can borrow mine, or come here and use
it.

ftp://66.117.156.8/IR_0026.jpg

ftp://66.117.156.8/IR_0032.jpg

[/quote]
Thanks, John. I think we are ok then up to 250mW. At least the resistors
are rated for that. I>ve got to visit you guys some day and look through
the FLIR. And maybe empty a pitcher at Zeitgeist.

Another peculiarity that surprised me was that the TO18 was stated at
83.3C/W to case by ST and the TO92 at the same by ON. Junction to
ambient was stated lower (!) for the TO92 even though it>s plastic.
Strange. I haven>t used TO packages in roughly two decades but now I
have to, for the proto run. I thought TO18 would have to be better but
it carries the collector and then some day it touches something ...
bzzzt ... POOF.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

HarryD · Guest

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:n1qe84pvvg5bfomsm6uvu2e8a42mf35ouk@4ax.com...
[quote]On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Sounds OK to me. We push regular 0805>s harder than that. Zero fails
so far.

We experimented with various resistors, 0603 through 1206, with a
thermal imager that has plenty of resolution to find the hot-spot temp
on all the parts.

Turns out that the actual part thetas are astronomical, and what cools
resistors is the copper pads and traces, more than the bodies
themselves. An 0603 soldered to big copper pours can dissipate as much
as a 1206 ditto; the hot spot temps are the same. That makes sense
physically, as theta is determined by the L/W ratio and the substrate
thickness, and all the resistors we checked were all 20 mil thick
alumina.

A better substrate, BeO or AlN, would help a bit, at great expense.

If there>s a ground plane close, that helps a lot.

The easiest thing to do is fire up the board and scope it with a Flir,
and see how hot stuff gets. You can borrow mine, or come here and use
it.

ftp://66.117.156.8/IR_0026.jpg

ftp://66.117.156.8/IR_0032.jpg

John

Thermal vias are your friend. Vias in pads are now standard procedure for[/quote]
most PCB houses. Put a thermal via in each pad and one under the center of
the part. Tie TVs to heat spreader on another plane.
JL, tell us more of your FLIR, type, cost and performance.
Cheers,
Harry

John Larkin · Guest

On Wed, 23 Jul 2008 18:40:04 GMT, "HarryD" <harryd@tdsystems.org>
wrote:

[quote]
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:n1qe84pvvg5bfomsm6uvu2e8a42mf35ouk@4ax.com...
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Sounds OK to me. We push regular 0805>s harder than that. Zero fails
so far.

We experimented with various resistors, 0603 through 1206, with a
thermal imager that has plenty of resolution to find the hot-spot temp
on all the parts.

Turns out that the actual part thetas are astronomical, and what cools
resistors is the copper pads and traces, more than the bodies
themselves. An 0603 soldered to big copper pours can dissipate as much
as a 1206 ditto; the hot spot temps are the same. That makes sense
physically, as theta is determined by the L/W ratio and the substrate
thickness, and all the resistors we checked were all 20 mil thick
alumina.

A better substrate, BeO or AlN, would help a bit, at great expense.

If there>s a ground plane close, that helps a lot.

The easiest thing to do is fire up the board and scope it with a Flir,
and see how hot stuff gets. You can borrow mine, or come here and use
it.

ftp://66.117.156.8/IR_0026.jpg

ftp://66.117.156.8/IR_0032.jpg

John

Thermal vias are your friend. Vias in pads are now standard procedure for
most PCB houses. Put a thermal via in each pad and one under the center of
the part. Tie TVs to heat spreader on another plane.
JL, tell us more of your FLIR, type, cost and performance.
Cheers,
Harry
[/quote]
It>s a model E45 with the wide-angle (germanium!) lens. You can
basically touch a part and still focus, so you can easily resolve the
hot spot temp on an 0603 or a SOT-23. It>s amazing... image a board
and learn all sorts of stuff.

The PC interface, sadly, is insane. It>s USB, but it>s a network
device, so you have to use their very klunky PC software. They should
have made it work like all the other cameras in the world.

Cost about $10K, and worth it. I think some new technologies are
coming on board, so prices will drop.

In that second pic I posted, we thought that the FPGA (under the blue
heat sink) was getting too hot as clock frequency increased, so we
were looking into clock gating and tedious stuff like that. A few
minutes with the Flir showed that the dacs (the white-hot blobs) are
in fact heating the FPGA.

John

John Larkin · Guest

On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

[quote]Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?
[/quote]

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

John

Joerg · Guest

John Larkin wrote:
[quote]On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

[/quote]
Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

John Larkin · Guest

On Fri, 25 Jul 2008 14:26:18 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

[quote]John Larkin wrote:
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.
[/quote]
My first ever job interview, I made the comment that I generally
preferred tubes (which I got free) to transistors, because transistors
were too easy to blow up. The prig said "that won>t do" and didn>t
hire me. Next interview, I said the same thing and that guy laughed
and did hire me. I designed about $100M of stuff for the second guy.

John

Joerg · Guest

John Larkin wrote:
[quote]On Fri, 25 Jul 2008 14:26:18 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

John Larkin wrote:
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.

My first ever job interview, I made the comment that I generally
preferred tubes (which I got free) to transistors, because transistors
were too easy to blow up. The prig said "that won>t do" and didn>t
hire me. Next interview, I said the same thing and that guy laughed
and did hire me. I designed about $100M of stuff for the second guy.

[/quote]
Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often tell
them "No, but a chip design wouldn>t make sense here, we can do that at
lower cost with off-the-shelf parts". Sometimes they walk away. The
companies of those who do are usually not heard of much anymore. Some of
them keep burning an enormous amount of cash until their VCs turn off
the spigot. The sad cases are where I could have really helped them with
$50-100K in cost, they decline, keep trying on their own, blow through
another few million bucks and then kablouie.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

John Larkin · Guest

On Fri, 25 Jul 2008 15:36:49 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

[quote]John Larkin wrote:
On Fri, 25 Jul 2008 14:26:18 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

John Larkin wrote:
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.

My first ever job interview, I made the comment that I generally
preferred tubes (which I got free) to transistors, because transistors
were too easy to blow up. The prig said "that won>t do" and didn>t
hire me. Next interview, I said the same thing and that guy laughed
and did hire me. I designed about $100M of stuff for the second guy.

Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often tell
them "No, but a chip design wouldn>t make sense here, we can do that at
lower cost with off-the-shelf parts". Sometimes they walk away. The
companies of those who do are usually not heard of much anymore. Some of
them keep burning an enormous amount of cash until their VCs turn off
the spigot. The sad cases are where I could have really helped them with
$50-100K in cost, they decline, keep trying on their own, blow through
another few million bucks and then kablouie.
[/quote]
I had that same experience with Metricon. I had a bog simple, cheap,
proven way to do what they needed. They had a complex mess, but said
it didn>t matter because "silicon is free." Remember Metricon?

John

Spehro Pefhany · Guest

On Thu, 24 Jul 2008 19:36:52 -0700, the renowned John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[quote]On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

John
[/quote]

Self-desoldering?

Best regards,
Spehro Pefhany
--
"it>s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

RRogers · Guest

On Jul 25, 6:36 pm, Joerg <notthisjoerg...@removethispacbell.net>
wrote:
[quote]John Larkin wrote:
On Fri, 25 Jul 2008 14:26:18 -0700, Joerg
notthisjoerg...@removethispacbell.net> wrote:

John Larkin wrote:
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoerg...@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?

Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.

My first ever job interview, I made the comment that I generally
preferred tubes (which I got free) to transistors, because transistors
were too easy to blow up. The prig said "that won>t do" and didn>t
hire me. Next interview, I said the same thing and that guy laughed
and did hire me. I designed about $100M of stuff for the second guy.

Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often tell
them "No, but a chip design wouldn>t make sense here, we can do that at
lower cost with off-the-shelf parts". Sometimes they walk away. The
companies of those who do are usually not heard of much anymore. Some of
them keep burning an enormous amount of cash until their VCs turn off
the spigot. The sad cases are where I could have really helped them with
$50-100K in cost, they decline, keep trying on their own, blow through
another few million bucks and then kablouie.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Believe it or not, even successful companies can have to much money.[/quote]
I worked at a place where their main product line was quite
successful. When it came to new development they never had to make
hard decisions, they could always throw money at a problem. As a
result a vast software and hardware infrastructure grew to resolve
various perceived (often self-inflicted) problems. Combine that with
ISO 2000 and such and you came to realize how Kafka came to his story;
and how bureaucracies form and survive.
The particular causes were many and in a lot of cases not due to overt
empire building; that made little difference when people who didn>t
understand what they were doing organized a project. Of course the
opposite also leads to insanity, penny pinching at a microscopic
level.

To paraphrase some Greeks, Yogi>s, and Buddhists
Balance is all, and to be cherished.

RayR

David Tweed · Guest

Joerg wrote:
[quote]Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often tell
them "No, but a chip design wouldn>t make sense here, we can do that at
lower cost with off-the-shelf parts". Sometimes they walk away. The
companies of those who do are usually not heard of much anymore. Some of
them keep burning an enormous amount of cash until their VCs turn off
the spigot. The sad cases are where I could have really helped them with
$50-100K in cost, they decline, keep trying on their own, blow through
another few million bucks and then kablouie.
[/quote]
I>m beginning to suspect that, in many cases, that (the last sentence)
is in fact the whole point of the operation. The high-level technical
people may or may not believe in the product/technology being developed,
but the executives are just in it for the boondoggle, living high on the
hog for as long as the investor money lasts, then moving on to a different
project.

Even the investors are not entirely unhappy with this situation --
they>re often looking for ways to take a loss without being too obvious
about it.

It>s just frustrating for the lower-level technical people who probably
don>t realize what>s going on and put a lot of good work into something
that just ends up in the dumpster. I once worked for a company where I
now firmly believe that this is what was (and may still be) going on.

-- Dave Tweed

Joerg · Guest

John Larkin wrote:
[quote]On Fri, 25 Jul 2008 15:36:49 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

John Larkin wrote:
On Fri, 25 Jul 2008 14:26:18 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

John Larkin wrote:
On Wed, 23 Jul 2008 09:59:26 -0700, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Hello All,

Got a circuit where in hindsight the client decided they need >10 times
the juice than initially spec>d. This was truly unforeseen for them and
we have to make it work at least for a proto series. Of course, now all
those 0805 resistors in the power path would exceed their usual 1/8W
spec. Found these at 1/3W:

http://www.susumu.co.jp/english/pdf/products-j01-07.pdf

I plan to run them around 200-250mW. Was expecting those to be really
tall to vent off some heat but they are surprisingly flat, only 0.4mm
high. Will this become a heat problem on FR-4 for stuff that can run
24/7? Any experience?
Can I interest you in 0402 at 10 watts? Or 0505 at 50 watts?

http://www.emct.com/microwavepassivecomponents-a43445.html

Ouch! That ought to do it for an impressive meltdown procedure on FR4.
Reminds me of a tube in a ceramic socket on phenolic. I was still a kid,
blissfully unaware of the limitations of some materials. Transistors
were very expensive in Germany so I built most stuff from salvaged
tubes, plucked out of radios and TV sets. Well, this thing worked for
months. Then one fine day there was fireworks, hissing and smoke. The
ceramic socket including tube had fallen through the charred hole that
had developed. Now I knew where that faint "amperage smell" was coming
from. Luckily the plate connector was up top and the tube fell in, but
didn>t tip over. Cuz I had "economized" on the power supply and ran
straight from 230V mains into a voltage doubler. The fuse was, ahem,
home made.
My first ever job interview, I made the comment that I generally
preferred tubes (which I got free) to transistors, because transistors
were too easy to blow up. The prig said "that won>t do" and didn>t
hire me. Next interview, I said the same thing and that guy laughed
and did hire me. I designed about $100M of stuff for the second guy.

Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often tell
them "No, but a chip design wouldn>t make sense here, we can do that at
lower cost with off-the-shelf parts". Sometimes they walk away. The
companies of those who do are usually not heard of much anymore. Some of
them keep burning an enormous amount of cash until their VCs turn off
the spigot. The sad cases are where I could have really helped them with
$50-100K in cost, they decline, keep trying on their own, blow through
another few million bucks and then kablouie.

I had that same experience with Metricon. I had a bog simple, cheap,
proven way to do what they needed. They had a complex mess, but said
it didn>t matter because "silicon is free." Remember Metricon?

[/quote]
These guys?
http://www.metricon.com/

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Joerg · Guest

David Tweed wrote:
[quote]Joerg wrote:
Similar things happen to consultants. Sometimes people present a task,
then ask whether I am versed in VHDL, Cadence and all that. I often
tell them "No, but a chip design wouldn>t make sense here, we can do
that at lower cost with off-the-shelf parts". Sometimes they walk
away. The companies of those who do are usually not heard of much
anymore. Some of them keep burning an enormous amount of cash until
their VCs turn off the spigot. The sad cases are where I could have
really helped them with $50-100K in cost, they decline, keep trying on
their own, blow through another few million bucks and then kablouie.

I>m beginning to suspect that, in many cases, that (the last sentence)
is in fact the whole point of the operation. The high-level technical
people may or may not believe in the product/technology being developed,
but the executives are just in it for the boondoggle, living high on the
hog for as long as the investor money lasts, then moving on to a different
project.

Even the investors are not entirely unhappy with this situation --
they>re often looking for ways to take a loss without being too obvious
about it.

It>s just frustrating for the lower-level technical people who probably
don>t realize what>s going on and put a lot of good work into something
that just ends up in the dumpster. I once worked for a company where I
now firmly believe that this is what was (and may still be) going on.

[/quote]
Luckily none of my clients, many of whom are VC-financed, is like that.
They all want to make it happen and I am sure most of them will. There
is always going to be risk, as in "venture" :-)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


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