IPC-4101 allows you to specify laminate thickness in three ways.
Classes A,B,C are the unclad laminate thickness measured mechanically
(micrometer). Class D is measured via microsection. Classes K,L,M are
measured mechanically over the cladding. The differences between A,B,C
are for different thickness tolerances Class C is the tightest). The
same holds for K,L,M.
> ----------
> From: John Denton[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;John Denton
> Sent: Thursday, August 13, 1998 8:54 AM
> To: [log in to unmask]
> Subject: Re: [TN] PCB substrate thickness
>
> Ian Squires wrote:
> >
> > Help,
> > Looking at substrate thickness on PWB
> > if i specify 2oz copper 1.6 mm would the substrate be the same size,
> thicker or thinner than 1oz copper 1.6 mm.
> >
> > Many thanks for any speedy replies (one of those urgent ones where
> the boss man is standing over me).
> >
> > Regards
> > Ian Squires
> > Senior Production Engineer
> > -------------------------------------------------------
> >
> > Graseby Dynamics Ltd
> > A Smiths Industries Company
> > Park Avenue, Bushey, Watford, Herts, WD2 2BW
> > Web Site: www.gradyn.co.uk
> > Phone: 01923-228566 xt 295
> > Fax: 01923-221361
> > E-mail: [log in to unmask]
> >
> > Registered in England no. 480992
> > Registered office:
> > 765 Finchley Road, London, NW11 8DS
> > -------------------------------------------------------
> >
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>
> HELLO IAN,
>
> IF YOU ARE SPEAKING IN GENERAL TERMS ABOUT COMMONLY ORDERED
> MATERIAL, THAN MY EXPERIENCE HAS BEEN THAT THE WAY PEOPLE REFER TO
> MATERIAL DEPENDS ON IF IT IS A DOUBLE-SIDED BOARD OR CORE LAMINATE
> THAT
> WILL BE USED TO BUILD A MULTILAYER. (ALL EX. BELOW ARE IN INCHES).
>
> IF IT DOUBLE-SIDED: STANDARD .062 1/1 MATERIAL WOULD HAVE A LAMINATE
> THICKNESS OF .0592 WITH A .0014 COPPER THICKNESS ON THE TOP AND
> BOTTOM.
> IF YOU SPEC .062 2/2, STANDARD LAMINATE THICKNESS IS .0564 WITH .0028
> THICK COPPER ON TOP AND BOTTOM. OVERALL THICKNESS REMAINS AT .062.
>
> IF IT IS CORE MAT'L FOR MULTILAYER: LET'S SAY 2 .014 CORES ARE BEING
> USED ON A 6 LYR WITH A FINISHED OVERALL THICKNESS OF .062 AFTER
> LAMINATION. IF YOU REFER TO .014 1/1 THAN THE LAMINATE THICKNESS IS
> ..014 WITH AN OVERALL THICKNESS OVER COPPER OF .0168. IF YOU REFER TO
> ..014 2/2 THAN ONCE AGAIN LAMINATE THICKNESS IS .014 BUT OVERALL
> THICKNESS IS NOW .0196.
>
> OF COURSE WHEN YOU GO TO ORDER MATERIAL FROM A VENDOR, THEY DON'T
> NECESSARILY KNOW IF YOU ARE BUILDING A M/L OR NOT. THE GOOD NEWS IS
> THAT THERE IS A VERY CLEAR CONCISE WAY OF CALLING OUT WHAT THICKNESS
> OF
> LAMINATE YOU WANT AND WHAT COPPER WEIGHT YOU WOULD LIKE (AS WELL AS
> THICKNESS TOLERANCES, PITS AND DENTS CLASSIFICATION AND WARP & TWIST
> ALLOWANCES, IF CRITICAL) IN MIL SPEC 13949 (WHICH IPC IS CURRENTLY
> CHANGING (HAS ALREADY CHANGED?). PERHAPS SOMEONE THERE CAN BRING YOU
> UP
> TO SPEED ON THE NEW SPEC IF IT HAS NOT ALREADY BEEN COVERED IN THIS
> FORUM.
>
> JOHN DENTON
> OMNI PWB
>
> I'M SURE THE IPC PEOPLE CAN GIVE YOU THE NEW SPEC NUMBER AND
>
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> Please visit IPC's web site (http://www.ipc.org) "On-Line Services"
> section for additional information.
> For technical support contact Hugo Scaramuzza at [log in to unmask] or
> 847-509-9700 ext.312
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>
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To unsubscribe: SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
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