SDDC Minutes April 25, 2002

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. Ray’s 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!