Jeff,
I work with the fab shop early in the design cycle to understand their
manufacturing capability. If I am interested in amount of copper for power
integrity, I use their minimum plating thickness in the analysis.
For SI, I use the maximum drill size for the finished hole size.
For backplanes, I deal with compliant pin (press fit) connectors so finished
hole plating and tolerance is critical. On my Fab drawing drill chart I specify
both drill size and finished hole size as recommended by connector vendor.
Example:
Drill: 0.7mm +/-0.025mm
Finished: 0.6mm +/-0.05mm
Similarly for mounting holes or any other critical holes, I specify drill size,
plated or not plated, and finished hole size where applicable on the fab
drawing.
Regards,
Bert Simonovich
Signal/Power Integrity Practitioner | Backplane Specialist | Founder
LAMSIM Enterprises Inc.
Web Site: http://lamsimenterprises.com
Blog: http://blog.lamsimenterprises.com/
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Jeff Loyer
Sent: December-29-15 2:15 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] How to specify via hole sizes
One thing that has bothered me forever is the ambiguity in specifying via hole
sizes. To my mind, there are instances where I might want to carefully specify
either, or both of, the outer and inner diameters (O.D., I.D., respectively) of
the via “columnâ€. But, that seems difficult (if not
impossible) to do with current common drill specifications (what a “finished
hole size†is seems to depend on context, some folks enter the approximate
drill size here). Can folks tell me how they ensure they get the correct
diameters for the following cases:
1) Signal integrity: I care about the O.D. This is going to be
(approximately) the size of actual drill used.
2) Mounting holes: I care about the O.D. This is going to be
(approximately) the size of actual drill used.
3) Press Fit connectors: I care about the I.D. This is the actual
drill size minus plating thickness.
4) Power Integrity: I care about both, I want to know the total copper
connecting my layers.
What does your drill chart look like that ensures you get what you need?
I’ve used “drill size†with some tolerance plus a “finished hole
size†with its tolerance, but that seems ambiguous. At this point, I think
we need to specify a “hole diameter†with a corresponding tolerance, and a
plating thickness range. While I would prefer to specify both O.D. and I.D.,
each with its corresponding tolerance, I’m told that folks in the industry
won’t know what I’m talking about if we do it that way. What has worked
best for folks?
Also, if someone has a key contact within IPC that I should be talking to, I
welcome that information too (please send it to me only to limit unwanted
distribution of anyone’s e-mail).
Thanks,
*Jeff Loyer*
Signal and Power Integrity Product Manager, Altium
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.7294 / Virus Database: 4489/11273 - Release Date: 12/28/15
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
