Capacitance of Double-sided PC Board

  • Thread starter Watson A.Name - 'Watt Sun
  • Start date
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Watson A.Name - 'Watt Sun

Guest
I took a piece of double-sided phenolic PC board and put it on the cap
meter. For a sheet that is 10.5 in. by 12 in. or 126 sq. in., I get
2074 pf, or 16.46 pF per sq. in., or 2.55 pF per sq. cm.

I didn't have any double sided glass epoxy - I used that up making PC
boards decades ago - so I was wondering how that compares to the glass
epoxy PC boards. Has anyone ever measured a piece? What did you get?

I've seen RF tx projects where the supports for the components are
made from small squares of PCB, having probably less than 2 pF. I've
also seen RF low pass filters where the PCB is used for the capacitor
to ground (plane) of the pi filter. So does a PCB capacitor have a
reasonable Q? I've also seen projects where they recommend using
teflon PC boards for low loss at RFs, usually UHF or above.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
On Sat, 16 Aug 2003 04:28:06 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

I took a piece of double-sided phenolic PC board and put it on the cap
meter. For a sheet that is 10.5 in. by 12 in. or 126 sq. in., I get
2074 pf, or 16.46 pF per sq. in., or 2.55 pF per sq. cm.

I didn't have any double sided glass epoxy - I used that up making PC
boards decades ago - so I was wondering how that compares to the glass
epoxy PC boards. Has anyone ever measured a piece? What did you get?

I've seen RF tx projects where the supports for the components are
made from small squares of PCB, having probably less than 2 pF. I've
also seen RF low pass filters where the PCB is used for the capacitor
to ground (plane) of the pi filter. So does a PCB capacitor have a
reasonable Q? I've also seen projects where they recommend using
teflon PC boards for low loss at RFs, usually UHF or above.
Click to expand...
Here's a link that'll get you some spec's for FR-4

http://www.apcircuits.com/resources/information/fr4_laminate.html

I'll also post an older DOS .exe and its BASIC source code to abse so
you can determine the capacitance knowing the dimensions and dielectric
constant of the dielectric without having to do any work!^)

--
John Fields
 
In article <tsdsjvcn4pt52aj0kkb9uu3k61or2j0jlq@4ax.com>,
jfields@austininstruments.com mentioned...
On Sat, 16 Aug 2003 04:28:06 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

I took a piece of double-sided phenolic PC board and put it on the cap
meter. For a sheet that is 10.5 in. by 12 in. or 126 sq. in., I get
2074 pf, or 16.46 pF per sq. in., or 2.55 pF per sq. cm.

I didn't have any double sided glass epoxy - I used that up making PC
boards decades ago - so I was wondering how that compares to the glass
epoxy PC boards. Has anyone ever measured a piece? What did you get?

I've seen RF tx projects where the supports for the components are
made from small squares of PCB, having probably less than 2 pF. I've
also seen RF low pass filters where the PCB is used for the capacitor
to ground (plane) of the pi filter. So does a PCB capacitor have a
reasonable Q? I've also seen projects where they recommend using
teflon PC boards for low loss at RFs, usually UHF or above.

Here's a link that'll get you some spec's for FR-4

http://www.apcircuits.com/resources/information/fr4_laminate.html
Click to expand...
Thanks - I think - anti-measling test??? Hokay...

I'll also post an older DOS .exe and its BASIC source code to abse so
you can determine the capacitance knowing the dimensions and dielectric
constant of the dielectric without having to do any work!^)
Click to expand...
I'll see if it's there. Yep, got both .bas and .exe.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
On Sat, 16 Aug 2003 04:28:06 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

I took a piece of double-sided phenolic PC board and put it on the cap
meter. For a sheet that is 10.5 in. by 12 in. or 126 sq. in., I get
2074 pf, or 16.46 pF per sq. in., or 2.55 pF per sq. cm.

I didn't have any double sided glass epoxy - I used that up making PC
boards decades ago - so I was wondering how that compares to the glass
epoxy PC boards. Has anyone ever measured a piece? What did you get?

I've seen RF tx projects where the supports for the components are
made from small squares of PCB, having probably less than 2 pF. I've
also seen RF low pass filters where the PCB is used for the capacitor
to ground (plane) of the pi filter. So does a PCB capacitor have a
reasonable Q? I've also seen projects where they recommend using
teflon PC boards for low loss at RFs, usually UHF or above.
Click to expand...
FR-4 varies a bit, but I usually assume 15 pF per square inch (2.3
/sqcm) for standard 0.062 thick stuff. The capacitance TC is
remarkable, typically about +950 PPM/K.

John
 
On Sat, 16 Aug 2003 11:10:58 -0700, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

FR-4 varies a bit, but I usually assume 15 pF per square inch (2.3
/sqcm) for standard 0.062 thick stuff. The capacitance TC is
remarkable, typically about +950 PPM/K.
Click to expand...
That would be 2.4 sq cm.

Aren't most PCBs these day G10?

We use .032 and .022 designs all the time.
 
On Sat, 16 Aug 2003 12:33:04 -0700, DarkMatter
<DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 16 Aug 2003 11:10:58 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

FR-4 varies a bit, but I usually assume 15 pF per square inch (2.3
/sqcm) for standard 0.062 thick stuff. The capacitance TC is
remarkable, typically about +950 PPM/K.

That would be 2.4 sq cm.

Aren't most PCBs these day G10?

We use .032 and .022 designs all the time.
Click to expand...
---
That would be...

1" = 2.54cm

1 in˛ = 1 in * 1 in = 2.54cm * 2.54cm = 6.452cm˛

15pF 15pF 2.325pF
---- = ------- = -------
1 in˛ 6.452cm˛ 1cm˛


Most PCB's these days are FR-4, which is G10 with a fire retardant added
to it.


--
John Fields
 
On Sat, 16 Aug 2003 15:36:44 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 16 Aug 2003 12:33:04 -0700, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 16 Aug 2003 11:10:58 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

FR-4 varies a bit, but I usually assume 15 pF per square inch (2.3
/sqcm) for standard 0.062 thick stuff. The capacitance TC is
remarkable, typically about +950 PPM/K.

That would be 2.4 sq cm.

Aren't most PCBs these day G10?

We use .032 and .022 designs all the time.

---
That would be...

1" = 2.54cm

1 in˛ = 1 in * 1 in = 2.54cm * 2.54cm = 6.452cm˛

15pF 15pF 2.325pF
---- = ------- = -------
1 in˛ 6.452cm˛ 1cm˛


Most PCB's these days are FR-4, which is G10 with a fire retardant added
to it.
Click to expand...

Weird. This Dark blather guy follows me around like some crazed
Pekingese, biting at my ankles. You'd think that "varies a bit" and
"15" would be hints that high-precision metric conversion wasn't
called for, and even then you'd think he could get the math right, and
maybe even state the engr units properly. And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant. So he insists in taking exception to a lot of what
I post, and invariably turns out to be 100% wrong. Some people crave
public humiliation, I suppose.

John
 
On Sat, 16 Aug 2003 16:24:11 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

In article <bk9tjvsulbspm8v9dfgbpis3sdq58u78ar@4ax.com>,
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com mentioned...
On Sat, 16 Aug 2003 15:36:44 -0500, John Fields
jfields@austininstruments.com> wrote:

[snip]
Most PCB's these days are FR-4, which is G10 with a fire retardant added
to it.


Weird. This Dark blather guy follows me around like some crazed
Pekingese, biting at my ankles. You'd think that "varies a bit" and
"15" would be hints that high-precision metric conversion wasn't
called for, and even then you'd think he could get the math right, and
maybe even state the engr units properly. And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant. So he insists in taking exception to a lot of what
I post, and invariably turns out to be 100% wrong. Some people crave
public humiliation, I suppose.

John

Oh yeah, that er, whatever. I don't see any of his posts anymore
since I put in the DMkill filter. It does wonders. Only see 'em when
someone quotes his blather.
Click to expand...
Same here. Everyone, do us all a favor and **please** stop responding
to DarkBlather. Put him in your permanent kill file.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

For proper E-mail replies SWAP "-" and "_"

I love to cook with wine. Sometimes I even put it in the food.
 
In article <bk9tjvsulbspm8v9dfgbpis3sdq58u78ar@4ax.com>,
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com mentioned...
On Sat, 16 Aug 2003 15:36:44 -0500, John Fields
jfields@austininstruments.com> wrote:

On Sat, 16 Aug 2003 12:33:04 -0700, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Sat, 16 Aug 2003 11:10:58 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

FR-4 varies a bit, but I usually assume 15 pF per square inch (2.3
/sqcm) for standard 0.062 thick stuff. The capacitance TC is
remarkable, typically about +950 PPM/K.

That would be 2.4 sq cm.

Aren't most PCBs these day G10?

We use .032 and .022 designs all the time.

---
That would be...

1" = 2.54cm

1 in˛ = 1 in * 1 in = 2.54cm * 2.54cm = 6.452cm˛

15pF 15pF 2.325pF
---- = ------- = -------
1 in˛ 6.452cm˛ 1cm˛


Most PCB's these days are FR-4, which is G10 with a fire retardant added
to it.


Weird. This Dark blather guy follows me around like some crazed
Pekingese, biting at my ankles. You'd think that "varies a bit" and
"15" would be hints that high-precision metric conversion wasn't
called for, and even then you'd think he could get the math right, and
maybe even state the engr units properly. And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant. So he insists in taking exception to a lot of what
I post, and invariably turns out to be 100% wrong. Some people crave
public humiliation, I suppose.

John
Click to expand...
Oh yeah, that er, whatever. I don't see any of his posts anymore
since I put in the DMkill filter. It does wonders. Only see 'em when
someone quotes his blather.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
On Sat, 16 Aug 2003 15:02:47 -0700, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant.
Click to expand...

You're a retard. This blanket presumption proves it.

We still use G10 everyday without the UL treatment.

For the last 25 years.

You couldn't be any more retarded.
 
Now that you mention it, he is annoying.

Cheers

"Jim Thompson" <Jim-T@analog_innovations.com> wrote in message
news:e3ftjvsng20k5ctrpir5r2j5lk7o87v51j@4ax.com...
On Sat, 16 Aug 2003 16:24:11 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> wrote:

In article <bk9tjvsulbspm8v9dfgbpis3sdq58u78ar@4ax.com>,
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com mentioned...
On Sat, 16 Aug 2003 15:36:44 -0500, John Fields
jfields@austininstruments.com> wrote:

[snip]
Most PCB's these days are FR-4, which is G10 with a fire retardant added
to it.


Weird. This Dark blather guy follows me around like some crazed
Pekingese, biting at my ankles. You'd think that "varies a bit" and
"15" would be hints that high-precision metric conversion wasn't
called for, and even then you'd think he could get the math right, and
maybe even state the engr units properly. And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant. So he insists in taking exception to a lot of what
I post, and invariably turns out to be 100% wrong. Some people crave
public humiliation, I suppose.

John

Oh yeah, that er, whatever. I don't see any of his posts anymore
since I put in the DMkill filter. It does wonders. Only see 'em when
someone quotes his blather.

Same here. Everyone, do us all a favor and **please** stop responding
to DarkBlather. Put him in your permanent kill file.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

For proper E-mail replies SWAP "-" and "_"

I love to cook with wine. Sometimes I even put it in the food.
Click to expand...
 
On Sat, 16 Aug 2003 19:55:19 -0700, "John Fields" <jfields@texas.net>
wrote:

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:kuftjvkqla0s2ju6i7i1sgi1ck1gvhl0an@4ax.com...
On Sat, 16 Aug 2003 15:02:47 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant.


You're a retard. This blanket presumption proves it.

We still use G10 everyday without the UL treatment.

For the last 25 years.

You couldn't be any more retarded.

---
Sure he could. He could be like you, a mean spirited, ignorant little dick
with an axe to grind, but he isn't and he's contributed a lot more here than
you ever have, (or will...) so what the fuck's the matter with you anyway?
Do you need attention so badly that you're willing to try to destroy the
fragile peace that's existed here for a while now just so you'll be noticed?
If that's your game then you've already lost. Be advised that you've been
noticed. Now go away.
Click to expand...
Whatsa matta John, just recovering from your Friday night drunken
stupor?

Go back to sleep!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

For proper E-mail replies SWAP "-" and "_"

I love to cook with wine. Sometimes I even put it in the food.
 
"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:kuftjvkqla0s2ju6i7i1sgi1ck1gvhl0an@4ax.com...
On Sat, 16 Aug 2003 15:02:47 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant.


You're a retard. This blanket presumption proves it.

We still use G10 everyday without the UL treatment.

For the last 25 years.

You couldn't be any more retarded.
Click to expand...
---
Sure he could. He could be like you, a mean spirited, ignorant little dick
with an axe to grind, but he isn't and he's contributed a lot more here than
you ever have, (or will...) so what the fuck's the matter with you anyway?
Do you need attention so badly that you're willing to try to destroy the
fragile peace that's existed here for a while now just so you'll be noticed?
If that's your game then you've already lost. Be advised that you've been
noticed. Now go away.

--
John Fields
 
On Sat, 16 Aug 2003 16:43:15 -0700, DarkMatter
<DarkMatter@thebarattheendoftheuniverse.org> wrote:
We still use G10 everyday without the UL treatment.
Click to expand...
If you are still calling out G10 on PCB fab drawings, you are likely
actually getting FR-4; it meets all the performance specs of G10, but
just uses a flame-supressing additive in the epoxy. Most PCB houses
stock FR4, since they often have to make UL boards. Pure (non-bromine)
G10 is basicly obsolete in the PCB industry. It is still sometimes
used for very thin boards in consumer applications (specifically
watches) because it punches a bit better than FR-4.

John
 
On Sun, 17 Aug 2003 00:14:07 GMT, "Martin Riddle"
<martinriddle@hotmail.com> Gave us:

Now that you mention it, he is annoying.
Click to expand...

Everything in life must be a riddle to you, fuckhead.
Like how to refrain from being a TOP POSTING RETARD in usenet.
Bone up on usenet posting practices and protocols, and then MAYBE the
shit you spew might not stink so bad that it isn't worth reading.
 
On Sat, 16 Aug 2003 19:27:35 -0700, Jim Thompson
<Jim-T@analog_innovations.com> Gave us:

"DarkMatter" <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:kuftjvkqla0s2ju6i7i1sgi1ck1gvhl0an@4ax.com...
On Sat, 16 Aug 2003 15:02:47 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

And anybody who has bought a
PC board in the last 25 years or so would know that everything is now
UL flame-retardant.


You're a retard. This blanket presumption proves it.

We still use G10 everyday without the UL treatment.

For the last 25 years.

You couldn't be any more retarded.

---
Sure he could. He could be like you, a mean spirited, ignorant little dick
with an axe to grind, but he isn't and he's contributed a lot more here than
you ever have, (or will...) so what the fuck's the matter with you anyway?
Do you need attention so badly that you're willing to try to destroy the
fragile peace that's existed here for a while now just so you'll be noticed?
If that's your game then you've already lost. Be advised that you've been
noticed. Now go away.

Whatsa matta John, just recovering from your Friday night drunken
stupor?

Go back to sleep!
Click to expand...
A working class hero is something to be, but you are still fucking
peasants, as far as *I* can see. --John Lennon 1970
 
On Sat, 16 Aug 2003 21:27:28 -0700, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> Gave us:

On Sat, 16 Aug 2003 16:43:15 -0700, DarkMatter
DarkMatter@thebarattheendoftheuniverse.org> wrote:

We still use G10 everyday without the UL treatment.


If you are still calling out G10 on PCB fab drawings, you are likely
actually getting FR-4; it meets all the performance specs of G10, but
just uses a flame-supressing additive in the epoxy. Most PCB houses
stock FR4, since they often have to make UL boards. Pure (non-bromine)
G10 is basicly obsolete in the PCB industry. It is still sometimes
used for very thin boards in consumer applications (specifically
watches) because it punches a bit better than FR-4.

John

We use it, unmasked, for HV applications. All the time. I know the
Click to expand...
difference.
 
On Sat, 16 Aug 2003 19:55:19 -0700, "John Fields" <jfields@texas.net>
Gave us:

Sure he could. He could be like you, a mean spirited, ignorant little dick
with an axe to grind, but he isn't and he's contributed a lot more here than
you ever have, (or will...) so what the fuck's the matter with you anyway?
Do you need attention so badly that you're willing to try to destroy the
fragile peace that's existed here for a while now just so you'll be noticed?
If that's your game then you've already lost. Be advised that you've been
noticed. Now go away.
Click to expand...

I'm sorry, dipshit... Did his insults not warrant getting the same
thing back in his face? I think that they did.

Take a hike, asswipe.
 
On Sat, 16 Aug 2003 19:27:35 -0700, Jim Thompson
<Jim-T@analog_innovations.com> wrote:


Whatsa matta John, just recovering from your Friday night drunken
stupor?
---
Click to expand...
Friday, Saturday, Tuesday... Who keeps track any more?^)

BTW, that flasher looks like it had a little ethanol behind it, no?

--
John Fields
 
On Sat, 16 Aug 2003 22:00:31 -0700, DarkMatter
<DarkMatter@thebarattheendoftheuniverse.org> wrote:


A working class hero is something to be, but you are still fucking
peasants, as far as *I* can see. --John Lennon 1970
Click to expand...
---
He's a real Nowhere Man,
Sitting in his Nowhere Land,
Making all his nowhere plans
for nobody.

John Lennon and Paul McCartney, 1965


--
John Fields
 
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