[SI-LIST] Re: Thermal properties of old pcbs
- From: "Lee " <leeritchey@xxxxxxxxxxxxx>
- To: <billh@xxxxxxxxxxxxx>, <ray.anderson@xxxxxxxxxx>, <dbrooks9@xxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 19 Dec 2014 11:56:43 -0800
As has already been pointed our FR-4 or FR-3 are UL classes that speak to
flame retardant characteristics of laminates. There are in excess of 30
materials that satisfy the FR-4 requirement, so using this as a call out for
materials to be used in a PCB amounts to no specification at all. For some
reason, our industry has decided that FR-4 is sufficient call out when
purchasing PCBs. That is relying on the fabricator to make the choices.
As can be seen from other discussions on the reflector, this is a very risky
way to do business.
-----Original Message-----
From: Bill Hargin (Nan Ya, USA)
Sent: Friday, December 19, 2014 11:05 AM
To: ray.anderson@xxxxxxxxxx ; dbrooks9@xxxxxxxxxxxxxxx ;
si-list@xxxxxxxxxxxxx
Cc: 'Ray Anderson'
Subject: [SI-LIST] Re: Thermal properties of old pcbs
Hi Doug:
Think "single-sided, consumer-electronics boards" for epoxy-paper (FR-3).
Paper (cheap) is used instead of E-glass for the reinforcement, and the
boards are "punchable," from a processing standpoint. FR-3 is covered in
IPC-4101/04, though there's no conductivity requirement.
From a thermal standpoint, I looked at one of our datasheets, and found
typical thermal conductivity in the 1-2 W/mK range. (E.g.,
http://www.npc.com.tw/Electronic_Materials_Div_e/images-1/201405/CEM-3-01HC.pdf
)
Bill Hargin
Director of North American Marketing
Nan Ya Copper-Clad Laminates
billh@xxxxxxxxxxxxx ▪ 425-301-4425 ▪ Skype: bill.hargin
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Ray Anderson
Sent: Friday, December 19, 2014 9:11 AM
To: dbrooks9@xxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Cc: Ray Anderson
Subject: [SI-LIST] Re: Thermal properties of old pcbs
Doug-
I think you'll find that 'FR4' is just a NEMA designation for flame
resistant 'epoxy glass'.
There was also G10 which glass -epoxy (G=general purpose) and G11 which was
temperature resistant.
'Epoxy paper' material was a cheap material with a NEMA designation FR3
(flame resistant epoxy paper) It had a max temp rating of 105C
Then there was the low of the low: XXXP (paper base phenolic) widely used
in cheap consumer devices like 6 transistor AM radio and such.
When it got old (within a few years) it really got brittle and tended crack
and break.
(Reference: ITT Reference Data for Radio Engineers 1968 edition page 5-32 )
-Ray
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Doug Brooks
Sent: Friday, December 19, 2014 8:34 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Thermal properties of old pcbs
I am reviewing an old article (1968) in which it refers to "copper
conductors an epoxy glass" and "copper conductors on epoxy paper."
Although I remember 1968 (that's a clue!!) I don't remember epoxy paper. I
am particularly interested in the thermal properties (thermal conductivity)
of these materials.
1. Am I safe in assuming "epoxy glass" is similar to todays FR4?
2. What would "epoxy paper" be like?
Thanks to all the old timers here!!
Doug
Check out our resources at http://www.ultracad.com
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