Ray,
I am looking at the section Tim specified and the very next page goes into
"foil web size" and clearance area (diameter) in the plane. Since we are
talking antipads I think this is the information you want.
This uses the Table 9-1 of IPC-2221 (which you now have)
Clearance area (diameter) = Max hole diameter + 2B
B= fabrication allowance per Table 9-1 of IPC-2221
If you need more I will see what I can do.
Dee Stover [log in to unmask]
Design Drafting Technician
National Optical Astronomy Observatory
950 N Cherry Ave
Tucson, AZ 85719
520-318-8489
FAX 520-318-8303
At 02:56 PM 9/23/1999 -0700, you wrote:
>Thanks, Tim. I have (what I think) to be the correct information from
>Paulo. Your reference to Table 9-1, Feature Location Tolerances, is not the
>same as the Standard Fabrication Allowance, which is what I was looking for.
>The Standard Fabrication Allowance is to be included in the formula for
>calculating the Minimum Land Size of pads and the clearance space around
>holes in the plane, not the Feature Location Tolerance.
>
>Ray
>
>----- Original Message -----
>From: <Tim Easterling> <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Thursday, September 23, 1999 2:02 PM
>Subject: Re: [DC] IPC Specs - Errors?
>
>
>> The information you are looking for is in IPC-2222
>> page 17 section 9.1.3 Clearance Area in Planes and
>> table 9-1 which provides feature location tolerances
>> for technology levels A,B,C.
>>
>>
>>
>>
>> Tim Easterling
>> Cadd Manager Commercial Engineering
>> SCI Systems Inc.
>> 8600 S. Memorial Parkway MS 200
>> Huntsville, Al. 35802
>> (256)882-4426 (ph)
>> (256)882-4700 x4426 (voicemail)
>> (256)882-4304 (fx)
>> ----------------------------------------------
>> Can you tell me on what page of IPC-2221/2222 the fabrication allowance
>> appears on? I do not have a copy, yet, but the people I have asked to
>check
>> say it is not in there. I have IPC-D-275, which has it in Table 5-10 on
>> page 64.
>>
>> ----- Original Message -----
>> From: Gary Ferrari <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Wednesday, September 22, 1999 6:43 PM
>> Subject: Re: [DC] IPC Specs - Errors?
>>
>>
>> > Ray,
>> >
>> > The IPC-2221/2222 makes quite a few improvements over the IPC-D-275,
>> > especially in the standard fabrication allowance. I would suggest that
>you
>> > obtain a copy and evaluate these differences against your experiences.
>Any
>> > comments would be welcomed.
>> >
>> > Additionally, IPC standards committees are not closed to the public.
>They
>> > welcme all comments and data submitted for review. I suggest if you have
>> data
>> > that supports your concerns, that you submit them to the committee for
>> > evaluation. The committee has scheduled a meeting at IPC Works in
>> Minneapolis
>> > on October 25th. I am sure they would like to meet with you and/or
>discuss
>> > your findings.
>> >
>> > Regards,
>> >
>> > Gary Ferrari
>> > Executive Director
>> > IPC Designers Council
>> > 80-350-9300
>> >
>>
>
>
|
