Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Tom Reilly

#12436

IPC 4101 | 3 March, 1999

We have recently had problems with bare boards coming in too thick. I would like to know how to properly specify the minimum and maximum thickness using the 13949F and IPC 4101 specs. (We currently use "MATERIAL: GFN 0620 C1/C1 A2A per MIL - P - 13949F"). To ensure we receive boards that are .062 +/- .005 how should the specification read. (Others have suggested GFN 0590 C1/C1 A2A). We are currently changing our specification to IPC 4101. To accomplish the same result here are the specification we could use. Please give me some recommendations which yield a more reliable thickness (IPC-4101 K21 0620 C1/C1 KA) or (IPC-4101 L21 0590 C1/C1 AA).

History: GFN 0620 C1/C1 A2A spec is as follows: 0.0000 GFN = FR4 material with no color added. 0.0620 0602 = .062 thick base material without copper 0.0030 C1/C1 = 1oz. copper each side 0.0000 A2A = Quality issues not effecting thickness 0.0030 60/40 Tin Lead 0.0020 Solder masking (LPI) ---------- 0.0700 Total thickness Max.

IPC-4101 K21 0620 C1/C1 KA spec is as follows: 0.0000 K21 = FR4 material with no color added. 0.0620 0602 = .062 thick base material with copper 0.0000 C1/C1 = 1oz. copper 2 sides(included in base thickness) 0.0000 KA = Quality issues not effecting thickness 0.0030 60/40 Tin Lead 0.0020 Solder masking (LPI) ---------- 0.0670 Total thickness Max.

Thanks, Tom

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Earl Moon

#12437

Re: IPC 4101 | 3 March, 1999

| We have recently had problems with bare boards coming in too thick. I would like to know how to properly specify the minimum and maximum thickness using the 13949F and IPC 4101 specs. (We currently use "MATERIAL: GFN 0620 C1/C1 A2A per MIL - P - 13949F"). To ensure we receive boards that are .062 +/- .005 how should the specification read. (Others have suggested GFN 0590 C1/C1 A2A). | We are currently changing our specification to IPC 4101. To accomplish the same result here are the specification we could use. Please give me some recommendations which yield a more reliable thickness (IPC-4101 K21 0620 C1/C1 KA) or (IPC-4101 L21 0590 C1/C1 AA). | | History: | GFN 0620 C1/C1 A2A spec is as follows: | 0.0000 GFN = FR4 material with no color added. | 0.0620 0602 = .062 thick base material without copper | 0.0030 C1/C1 = 1oz. copper each side | 0.0000 A2A = Quality issues not effecting thickness | 0.0030 60/40 Tin Lead | 0.0020 Solder masking (LPI) | ---------- | 0.0700 Total thickness Max. | | IPC-4101 K21 0620 C1/C1 KA spec is as follows: | 0.0000 K21 = FR4 material with no color added. | 0.0620 0602 = .062 thick base material with copper | 0.0000 C1/C1 = 1oz. copper 2 sides(included in base thickness) | 0.0000 KA = Quality issues not effecting thickness | 0.0030 60/40 Tin Lead | 0.0020 Solder masking (LPI) | ---------- | 0.0670 Total thickness Max. | | | | Thanks, | Tom | 4101 and many of the other conversion standards and specifications often are difficult to manage. I do appreciate your interest but would ask why you are not specifying MLB constructions based on clearly indicating them on the master drawing to the extent dielectric thickness and, maybe, resin/glass stypes are clearly indicated with overall thicknesses and tolerances. This allows your carefully "qualified" board shop to make decisions concerning 4101/13949 issues. Of course I already know the answer to this one.

There are two other options. One is to contact IPC for clarification. The other is to do number one while contacting carefully qualified laminate suppliers confronting the same issues.

There is one other thing. I've never been able to design or fabricate an MLB with less than 10% dielectric or overal thickness tolerance. This would mean the + or - 5 mil tolerance would be out the window on a .062" thick board. Also, I would opt on the low side with regard to constructions and stay with semi-resin rich glass styles as 2113's and 2116's. If you must design MLB's with all 5 core materials, your options get more difficult as does your dimensional stability.

Earl Moon

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Luis Alberto Garc�a G.

#12438

Re: IPC 4101 | 12 March, 1999

Please I want to know where I can get IPC standards. If you can help me please, send me a message by e-mail.

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