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 > > > >