Werner and Genny,
My past experience with laminate suppliers is that they produce only a certain number of laminate formulations. The supplier then compares the properties of the laminate with the different slash sheets. If the laminate meets the requirements of a slash sheet it is added to the supplier's product document. Therefore, it is up to the designer to review the laminate slash sheets and know what properties are call out versus what properties are required for a particular job.
For instance, if the design drawing calls for a laminate with a Tg of 180 +/- 10 C rather than just a /1 call out and several specification slash sheets (/1, /2, & /3) call for a Tg with a minimum value of 180C (/1), 200C (/2) and 220C (/3) respectively, then the PWB manufacturer must chose to fabricate the PWB with a laminate that only lists the /1 slash sheet. But if the designer only puts /1 on the drawing as the material to use then the PWB manufacturer could use laminate the meets the slash sheet requirements of /1, /2, and /3. Thus, unkowingly compromising the design if the Tg truly needed to be in the 180C range.
If a suppliers product documentation lists /1, /2 and /3 then the laminate manufacturer may have decided that it is more cost effective to manufacture one line of product with a Tg of 220C that meets the slash sheet requirements for all 3 slash sheets (/1, /2 and /3).
Again, if the design requires a laminate with specific properties and the slash sheet specified only gives general properties then the designer needs to specify the exact requirements on the drawing or a source control spec.
Hope this helps,
Tom
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Friday, October 02, 2009 1:13 PM
To: [log in to unmask]
Subject: Re: [TN] IPC-4101B slash sheets
Hi Genny,
How does your PCB fabricator know what to build for you, if you do not specify? What assembly processes do they experience? What is the purpose of your assemblies? What environments do they see?
"I have seen some material datasheets for the raw laminate that mention meeting multiple slash sheets, which I don't understand"-neither do I, and i have never seen this.
Werner
-----Original Message-----
From: Genny Gibbard <[log in to unmask]>
To: [log in to unmask]
Sent: Fri, Oct 2, 2009 1:47 pm
Subject: Re: [TN] IPC-4101B slash sheets
OK, but if you have never ever tied your laminate requirements to the
4101 (A, B, or C) in the first place, or forced your PCB fabricators to follow a specific slash, I am not sure what the importance of it is, or how to use it. There seem to be an awful lot of different slash sheets.
I have seen some material datasheets for the raw laminate that mention meeting multiple slash sheets, which I don't understand, either. How can it meet so many different ones?
We have usually mentioned much more generic specs.
Maybe all my questions would be answered if I actually bought the IPC doc and read it, but I need to justify to my company to spend money on it, first.
Genny
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: October 2, 2009 11:12 AM
To: [log in to unmask]
Subject: Re: [TN] IPC-4101B slash sheets
Hi Genny,
IPC-4101B is now obsolete with the
publication of IPC-4101C.? This
document provides the broad specifications for the various base materials available for PCBs; the various slash sheets are the specific specifications for a large variety of groups of base materials developed for different purposes.
While 4101 goes a long way to describe the minimum requirements for each slash sheet group, the document and the slash sheets are not comprehensive enough for material specification per se.
Thus, on the drawings for PCBs of the customers, more specific requirements need to be made than are available on the slash sheets.
This has become particularly important for PCBs subject to Pb-free solder assembly and the much higher soldering temperatures required.
For this reason, I have developed a white Paper giving my clients detailed recommendations for the specification of PCBs to survive Pb-free assembly.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
-----Original Message-----
From: Genny Gibbard <[log in to unmask]>
To: [log in to unmask]
Sent: Fri, Oct 2, 2009 1:00 pm
Subject: [TN] IPC-4101B slash sheets
I have never seen a copy of the IPC-4101B.
I keep hearing talk of the slash sheets. I am not sure I understand what this spec is for or how to use it, and whether I should try to get a copy in our facility.
Can someone give=2
0me a quick overview about this standard?
Genny
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