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April 2008

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Subject:
From:
Jack Olson <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jack Olson <[log in to unmask]>
Date:
Tue, 29 Apr 2008 12:39:04 -0500
Content-Type:
text/plain
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text/plain (1 lines)
Phil,

I just found it.
Look in section 4.3.7.5 of IPC-2222

It is expanded to Table 4-10 of IPC-2222A working draft
and it is amazingly more complicated than my "10%" answer!!!!

(I don't know if Revision A is published yet. If it is, refer to THAT)


  *

Table 4-10 Printed Board Thickness Tolerance Levels *
 *

Board Thickness (mm) [in] *
*

Tolerances by Level *
 *

Level *
*

A *
*

B *
*

C *
 *

As applied Base to Base *

   ˜ 1.6 [0.062]

+ 15 %

+ 12 %

+ 10 %

> 1.6 to ˜ 2.3 [0.062 to 0.090]

+ 12 %

+ 10 %

+ 7 %

> 2.3 to ˜ 3.8 [0.090 to 0.149]

+ 10%

+ 7 %

+ 5 %

> 3.8 to ˜ 6.4 [0.149 to 0.251]

+ 10%

+ 7 %

+ 5 %
 *

As applied over Final Finishes and Coatings *

˜ 1.6 [0.062]

+ 20 %

+ 15 %

+ 12 %

> 1.6 to ˜ 2.3 [0.062 to 0.090]

+ 15 %

+ 12 %

+ 10 %

> 2.3 to ˜ 3.8 [0.090 to 0.149]

+ 12 %

+ 10 %

+ 6 %

> 3.8 to ˜ 6.4 [0.149 to 0.251]

+ 12 %

+ 10 %

+ 6 %

1.6 = 0.062

2.3 = 0.090

3.8 = 0.149

6.4 = 0.251


On 4/29/08, Jack Olson <[log in to unmask]> wrote:
>
> Phil,
>
> I can only give you a partial answer (because I can't find it in any IPC
> docs either!)
> The way you are specifying it is fine, except you must allow
> +/-10% tolerance
> (I know it is 10%, but I searched every relevant doc I have for "10%",
> can't find it)
>
> The reason it is most often measured to include the plated metal,
> is because in the past it most often mattered for edge connectors.
> The edge connector had to include the distance from the gold finish
> on one side to the gold finish on the other
>
> Jack
>
> p.s. Final thickness is never measured to include the mask.
> p.s.s. I can post your question over on the IPC Designer's Council if you
> want me to?
>
>
> >
> > Phil Nutting <[log in to unmask]>
> > Sent by: TechNet <[log in to unmask]>
> > 25.04.2008 21:52
> > Please respond to
> > TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> > Phil Nutting <[log in to unmask]>
> >
> >
> > To
> > [log in to unmask]
> > cc
> >
> > Subject
> > [TN] Specifying board thickness
> >
> >
> >
> >
> >
> >
> > Hi Technetters,
> >
> > We are reviewing how we specify finished circuit board thickness to make
> > sure we get what we think we specified.  Recent events have placed what
> > we
> > specify under scrutiny.  I've looked through IPC-2221, IPC-2222, IPC-
> > 4101B, IPC-6012B and IPC-7351A with no luck.
> >
> > Currently our documentation calls for 0.059" finished board thickness
> > without measuring the thickness of the copper.  Presumably when the
> > copper
> > is added we get to 0.062" finished thickness which is important when we
> > start stacking circuit boards on standoffs.
> >
> > How do others specify circuit board thickness?
> >
> > Is there an IPC spec I can quote chapter and verse?
> >
> > Thanks in advance.
> >
> > Phil Nutting
> > Design for Manufacturing Engineer
> > Kaiser Systems, Inc.
> > 126 Sohier Road
> > Beverly, MA 01915
> > voice: 978-922-9300 x1310
> > fax: 978-922-8374
> > e-mail: [log in to unmask]
> > www.kaisersystems.com
> >
> >

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