Location -
Overland
Data, Inc.,
4820
Overland Avenue, San Diego, CA 92123
Tel: (858)
571-5555
Time 6:00PM
Core group members attending:
Leslie Gomez, President
Bill Brooks, Web/Communications Officer
Bill Gebhardt, Treasurer
Attending Sohan Abraham from Denso, Roland Ancheta from Ericsson,
Rene Cabanban from Denso, Dave Catanzaro from Employment Strategies,
John Foster from Broadband Innovations, Rich Hagan from Perigrine
Semiconductor, Ron Haynie from Denso, Tony Ornelas from Denso, Donna
Perry from BTS, Julie Rachey, Sean Rundgren from Pacific Design, and
Keo Summit from Nokia.
Meeting Agenda-
6:00PM Baja Fresh Mexican dinner arranged by SDDC, Drinks and meeting
room provided by Overland Data.
6:30PM Meeting call to order - New business, announcements
6:45PM Ray Wheeler, of Cymer Data and UCSD Geometric Dimensions and
Tolerances for PCB Designs
8:30PM Meeting adjourned
Meeting Synopsis:
Bill Brooks gave an update on what is
happening at the IPC Designers Council after his trip to PCB WEST in
Santa Clara, California. He covered the Education Committee actions
and the College Committee agenda. Bill was elected to the Executive
Board of the IPC Designers Council, the CAD specific committee, the
Education Committee, and the Steering Committee. Bill is also going to
be an Adjunct Instructor for PCB Design at Palomar College in San
Marcos, Calif. He will be teaching the DT-210 PCB Design class using
Mentor Graphics Expedition software in the Fall Semester.
Ray opened
with a lively discussion on GD&T and the applications as related to
PCB Design. He covered the common pitfalls in establishing a datum,
the feature control box and use of the datum(s) in dimensioning a PCB.
Ray talked about the traditional approaches to dimensioning and showed
the most common mistakes a designer makes in dimensioning a part.
Specs referenced in his discussion were IPC-2615, IPC-2221 and ASME Y14.5M-1994. Issues were
hole tolerances, land locations, board edges
and features, and flatness, bow and twist. Terms discusses were, MMC
Maximum material condition, LMC least material condition, RFS
Regardless of Feature size, Virtual condition or the size plus the
tolerance envelope, bonus tolerances, How to build a functional gage
for inspection, and the feature control frame. Ray spoke of the datum
features that define the geometry of the PCB by the Primary or side
farthest from the operator, the Secondary or side nearest the operator
and Tertiary datum or a hole or perpendicular feature that locks the
PCB in all 3 planes. He talked about straightness, Flatness,
Circularity, Cylindricity, Profile tolerance, Coplanarity,
perpendicularity, angularity, parallelism, true position,
concentricity, symmetry and the Datum Reference Frame. He walked
through some mechanical examples of how to dimension mated parts.
There was a 22-page handout and Ray said he would be glad to answer
any questions and passed out his business card. Rays email is
Ray_Wheeler@cymer.com.
We want to thank
Overland Data for letting us use their fine facilities to hold our
meeting!
Thanks to all who attended for a great
meeting. Your involvement and support makes the San Diego Chapter a
valuable asset to the San Diego PCB Design community. We look forward
to seeing all of you at our next meeting!