DPAK resistor

J

John Larkin

Guest
http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Wednesday, July 24, 2019 at 11:18:55 AM UTC-4, John Larkin wrote:
http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.
Click to expand...
We use Caddock resistors. The fine print says it will do 2.5 watts
with 1" squared of 2 oz copper on pcb.

George H.
Several other people make similar dpak resistors. I'll get some others
and test them too.
We use Caddock resistors.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics
Click to expand...
 
John Larkin wrote...
http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element
to the tab. Caddock says 2.3 pF, which is probably one end.
Click to expand...

What's the capacitance end-to-end, with the tab floating?


--
Thanks,
- Win
 
On 24 Jul 2019 17:36:03 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element
to the tab. Caddock says 2.3 pF, which is probably one end.

What's the capacitance end-to-end, with the tab floating?
Click to expand...

It's a 50 ohm resistor, so it would be hard for me to measure that.

Since each end is about 2.3, the two in series must be at least half
that. I'll probably always ground the tab, since I need to heat sink
it to my ground plane.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.
Click to expand...

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.

Maybe I could measure the temperature of the tab with a thermistor and
shut down if it gets extreme. What would that be for a PC board? 120C
or so?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
John Larkin wrote...
The real issue is, how much power can I allow one
of these to dissipate on a PC board? 8 or even
10 watts would be useful right now, but that might
get scary.
Click to expand...

I struggled with 2.5 watts, saw 150C surface temps.
After adding a heatsink with dozens of nice prongs,
saw much lower temps on the prongs, but still 150C
at heatsink base = SMT component surfaces. Only way
to get rid of the heat is to add airflow with a fan.


--
Thanks,
- Win
 
mandag den 29. juli 2019 kl. 02.33.55 UTC+2 skrev John Larkin:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.

Maybe I could measure the temperature of the tab with a thermistor and
shut down if it gets extreme. What would that be for a PC board? 120C
or so?
Click to expand...

some info here, https://www.pcbcart.com/pcb-fab/high-tg-pcb.html
 
On 28 Jul 2019 18:38:34 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

The real issue is, how much power can I allow one
of these to dissipate on a PC board? 8 or even
10 watts would be useful right now, but that might
get scary.

I struggled with 2.5 watts, saw 150C surface temps.
Click to expand...

Was that a dpak?

After adding a heatsink with dozens of nice prongs,
saw much lower temps on the prongs, but still 150C
at heatsink base = SMT component surfaces. Only way
to get rid of the heat is to add airflow with a fan.
Click to expand...

I'm thinking that I might have a lot of vias to a big bottom-side
pour, than a gap-pad to the bottom of the aluminum box.

My resistor will get really hot if the user shorts my output (instead
of terminating in 50 ohms) so the thermistor shutdown idea looks neat.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
Click to expand...
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)

How about 2 or 3 in series or parallel?

George H.
Maybe I could measure the temperature of the tab with a thermistor and
shut down if it gets extreme. What would that be for a PC board? 120C
or so?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
Click to expand...
 
On Mon, 29 Jul 2019 07:00:01 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)
Click to expand...

PCB copper doesn't conduct heat very well. 1 oz is about 70 K/W per
square. If there is a hot part soldered to a square of layer 1 copper,
there is dimishing benefit from making the copper bigger; an infinite
sheet will have some asymptotic theta. What helps is to use a bigger
part to get a bigger footprint, or equivalently via to additional
layers to spread the heat quicker. Lots of vias.

How about 2 or 3 in series or parallel?
Click to expand...

That would help thermally, provided they are not clustered together.
But spreading them out has its own problems.

I have a rough idea about thetas.

https://www.dropbox.com/s/auaok1fsitpfi9h/T900_1117_1.JPG?raw=1

I could maybe get to 10 k/w, maybe a little less, with some
bottom-side cooling help. But how hot might I allow the resistor to
get? We reflow solder boards at over 200C, and they survive. Maybe
allow 150C under fault (user shorts my output) conditions?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Monday, July 29, 2019 at 11:22:39 AM UTC-4, John Larkin wrote:
On Mon, 29 Jul 2019 07:00:01 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)

PCB copper doesn't conduct heat very well. 1 oz is about 70 K/W per
square. If there is a hot part soldered to a square of layer 1 copper,
there is dimishing benefit from making the copper bigger; an infinite
sheet will have some asymptotic theta. What helps is to use a bigger
part to get a bigger footprint, or equivalently via to additional
layers to spread the heat quicker. Lots of vias.


How about 2 or 3 in series or parallel?

That would help thermally, provided they are not clustered together.
But spreading them out has its own problems.
Click to expand...
Even clustered you'll still get the benefit of less R-thermal from the
heater element to the outside of the package. (well same R_thermal, but
shared heat load.)
I have a rough idea about thetas.

https://www.dropbox.com/s/auaok1fsitpfi9h/T900_1117_1.JPG?raw=1

I could maybe get to 10 k/w, maybe a little less, with some
bottom-side cooling help. But how hot might I allow the resistor to
get? We reflow solder boards at over 200C, and they survive. Maybe
allow 150C under fault (user shorts my output) conditions?
Click to expand...
Hmm, testing some to-220 pac resistors, I melted the solder junction a few
times (built in thermal fuse :^). The resistors seemed to survive without
a change in R... at least a few times. Eventually I noticed that the
resistance had dropped and I replaced it.
My assumption is that R's are more durable than IC's (at least
temperature-wise)

George H.
--

John Larkin Highland Technology, Inc

lunatic fringe electronics
Click to expand...
 
mandag den 29. juli 2019 kl. 17.22.39 UTC+2 skrev John Larkin:
On Mon, 29 Jul 2019 07:00:01 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)

PCB copper doesn't conduct heat very well. 1 oz is about 70 K/W per
square. If there is a hot part soldered to a square of layer 1 copper,
there is dimishing benefit from making the copper bigger; an infinite
sheet will have some asymptotic theta. What helps is to use a bigger
part to get a bigger footprint, or equivalently via to additional
layers to spread the heat quicker. Lots of vias.


How about 2 or 3 in series or parallel?

That would help thermally, provided they are not clustered together.
But spreading them out has its own problems.

I have a rough idea about thetas.

https://www.dropbox.com/s/auaok1fsitpfi9h/T900_1117_1.JPG?raw=1

I could maybe get to 10 k/w, maybe a little less, with some
bottom-side cooling help. But how hot might I allow the resistor to
get? We reflow solder boards at over 200C, and they survive. Maybe
allow 150C under fault (user shorts my output) conditions?
Click to expand...

you can get pcbs made with copper inserts

https://www.aspocomp.com/sites/default/files/Product%20photos/Transistor_T_coin_2.jpg
 
tirsdag den 30. juli 2019 kl. 18.56.57 UTC+2 skrev John Larkin:
On Tue, 30 Jul 2019 09:41:36 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

mandag den 29. juli 2019 kl. 17.22.39 UTC+2 skrev John Larkin:
On Mon, 29 Jul 2019 07:00:01 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)

PCB copper doesn't conduct heat very well. 1 oz is about 70 K/W per
square. If there is a hot part soldered to a square of layer 1 copper,
there is dimishing benefit from making the copper bigger; an infinite
sheet will have some asymptotic theta. What helps is to use a bigger
part to get a bigger footprint, or equivalently via to additional
layers to spread the heat quicker. Lots of vias.


How about 2 or 3 in series or parallel?

That would help thermally, provided they are not clustered together.
But spreading them out has its own problems.

I have a rough idea about thetas.

https://www.dropbox.com/s/auaok1fsitpfi9h/T900_1117_1.JPG?raw=1

I could maybe get to 10 k/w, maybe a little less, with some
bottom-side cooling help. But how hot might I allow the resistor to
get? We reflow solder boards at over 200C, and they survive. Maybe
allow 150C under fault (user shorts my output) conditions?


you can get pcbs made with copper inserts

https://www.aspocomp.com/sites/default/files/Product%20photos/Transistor_T_coin_2.jpg



We could also hog a hole in the board, under the part, and bring up an
aluminum pillar from the bottom of the box. Both would be more
expensive than a bunch of vias. Vias are basically free.
Click to expand...

that's the point of the insert, like a vias it comes with the pcb

we recently used in an RF PA under the main transistor(s) I don't think
it cost that much more than a regular PCB
 
On Tue, 30 Jul 2019 09:41:36 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

mandag den 29. juli 2019 kl. 17.22.39 UTC+2 skrev John Larkin:
On Mon, 29 Jul 2019 07:00:01 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Sunday, July 28, 2019 at 8:33:55 PM UTC-4, John Larkin wrote:
On Wed, 24 Jul 2019 08:18:44 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

http://www.caddock.com/Online_catalog/Mrktg_Lit/MP725.pdf

This has a metal tab, like a DPAK transistor, but isolated.

I measure about 5 pF from both ends of the resistive element to the
tab. Caddock says 2.3 pF, which is probably one end. It seems awfully
fast.

https://www.dropbox.com/s/m6lj41uv1prgavy/MP725_TDR.JPG?raw=1

It's rated for 25 watts, but I wonder how much it's good for mounted
on a PCB. I can via the tab to the ground plane, and maybe to a patch
of copper on the bottom of the board. Something like 6 watts would do
for now, which is probably OK. It won't die from getting hot, so my
concern is heating other parts and scorching the board.

Several other people make similar dpak resistors. I'll get some others
and test them too.

Just got some samples of different style DPAK resistors.

https://www.dropbox.com/s/l1z8e64xawqgylf/Dpak_Resistors.JPG?raw=1

The Riedon part is rated for 25 watts, and the Ohmite for 45!!!

I'll test them for capacitances and TDR.

The real issue is, how much power can I allow one of these to
dissipate on a PC board? 8 or even 10 watts would be useful right now,
but that might get scary.
That sound like a lot... but you know more about those things than
most of us here. (An interesting question would be; How much does
each square inch of added PCB copper add to the cooling at the device.
Assuming copper is added at the periphery.)

PCB copper doesn't conduct heat very well. 1 oz is about 70 K/W per
square. If there is a hot part soldered to a square of layer 1 copper,
there is dimishing benefit from making the copper bigger; an infinite
sheet will have some asymptotic theta. What helps is to use a bigger
part to get a bigger footprint, or equivalently via to additional
layers to spread the heat quicker. Lots of vias.


How about 2 or 3 in series or parallel?

That would help thermally, provided they are not clustered together.
But spreading them out has its own problems.

I have a rough idea about thetas.

https://www.dropbox.com/s/auaok1fsitpfi9h/T900_1117_1.JPG?raw=1

I could maybe get to 10 k/w, maybe a little less, with some
bottom-side cooling help. But how hot might I allow the resistor to
get? We reflow solder boards at over 200C, and they survive. Maybe
allow 150C under fault (user shorts my output) conditions?


you can get pcbs made with copper inserts

https://www.aspocomp.com/sites/default/files/Product%20photos/Transistor_T_coin_2.jpg
Click to expand...

We could also hog a hole in the board, under the part, and bring up an
aluminum pillar from the bottom of the box. Both would be more
expensive than a bunch of vias. Vias are basically free.

I did that on my Pockels Cell driver, cut a big hole for the Cree fets
to access the water-cooled baseplate.

https://www.dropbox.com/s/r3z4fno9a6t8ddy/T850_Cree.jpg?raw=1


Machining is expensive.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
About PCBs, just some weeks ago we got quote for 2 layer thick aluminium PCB

To my amazement they came out cheaper than copper layered PCBs

Cheers

Klaus
 
On 7/30/19 2:00 PM, klaus.kragelund@gmail.com wrote:
About PCBs, just some weeks ago we got quote for 2 layer thick aluminium PCB

To my amazement they came out cheaper than copper layered PCBs

Cheers

Klaus
Click to expand...

From whom?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
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