If it is important to the design function state it down to the details
needed for performance. If you just need a 8 layer, 1/16 board, FR4
with 1 oz copper, this fits neatly into a Note 2 and allow the
fabricator to build the unit as economically and IAW there process
needs. You Note 1 for specification will cover you on how the package
should perform.
The disadvantage of getting to specific where it is not needed becomes
an issue from supplier to supplier. You talk to Joe Circuits and they
use a 3070 and 106 glass and Short Circuits uses just 2116 and 1080 -
this becomes a real issue when you become that specific.
On the other hand when your need a .015" H/2 6010LM bonded to a .030"
H/1 RT3206 with 3xRO4450 then this becomes a needed part of you
construction detail. In this case include all the specifics on
tolerances, etc.
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302
Voice - 802.257.4571 ext 21
Fax - 802.257.0011
<http://www.vtcircuits.com/>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Anslow, Phillip
Sent: Thursday, September 28, 2006 3:46 AM
To: [log in to unmask]
Subject: [TN] Build Structure Communication
Dear Fellow TechNetters,
Would you please share how you communicate your PCB build structures to
PCB fabricators, or, if you are a fabricator, how those which are
easiest to understand are presented to you.
For copper, is it best to quote (i) Nominal start weight or thickness,
(ii) minimum finished thickness to IPC-2221A tables before and/or after
plating if applicable?
For dielectric thickness, (i) specify value, (ii) give range (iii) leave
open?
Your advice and expertise is greatly appreciated.
Many thanks and regards,
Phil
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