Issue link: https://iconnect007.uberflip.com/i/1509257
48 DESIGN007 MAGAZINE I OCTOBER 2023 the dots. Again, the rules were all done with standard 60-mil-wide round and oblong pads, but I could push the envelope to 8-mil traces which was the narrowest ink pen for the XY plotter. e challenge was to etch the 8-mil traces without a break. But a touch-up pen on the photoresist fixed that. is was sufficient for prototype boards we were producing for university research projects. e clock speed was 10 MHz max, so signal integrity was not an issue and planes were not considered. In 1987, I was thrown in the deep end. e R&D company I was working for purchased IC and PCB design soware from Daisy (later acquired by Intergraph Electronics). Board- Master PCB was a complex UNIX package that had a steep learning curve so the focus was on learning the tool so that we could produce our new fiber broadband network. e prototype network took 18 months of colossal effort to produce and it proved the concept. However, it was not manufacturable in quantities. Our technology partners—Siemens and Alcatel in Europe, and US West and Bell Atlantic in the U.S.—provided us with their design rules so that all our equipment could be assembled in any modern production facility worldwide. I also obtained the IPC standards for PWB design and manufacture, and merged them into a complete set of design rules. ree years later, we were ready for mass production. e lesson here is that anyone can produce a prototype but it takes much, much more effort (at first) to produce a manufacturable product. However once set up, the constraints become part of the design process and take little extra effort to enforce. Where Does a Newbie Designer Start? IPC was founded in 1957, and has provided the worldwide electronics industry with stan- dards for the design and manufacture of printed circuit boards, compiled over the years with the support of both committee and industry members. IPC has more than 300 active mul- tilingual industry standards that cover nearly every stage of the electronics product develop- ment cycle. IPC-2221B is the foundation design stan- dard for all documents in the IPC-2220 series. e series is built around the IPC-2221, Generic Standard on Printed Board Design, the base document that covers all generic require- ments for printed board design, regardless of materials. From here, the designer chooses the appropriate sectional standard for a specific technology. All five sectional standards are included in the series: • IPC-2222B, Sectional Design Standard for Rigid Organic Printed Boards • IPC-2223E, Sectional Design Standard for Flexible Printed Boards • IPC-2224, Sectional Standard for Design of PWBs for PC Cards • IPC-2225, Sectional Design Standard for Organic Multichip Modules (MCM-L) and MCM-L Assemblies • IPC-2226, Sectional Design Standard for High-Density Interconnect (HDI) Printed Boards is series provides coverage on material and final finish selection, current-carrying capacity and minimum electrical clearances, test-specimen design, guidelines for V-groove scoring, dimensioning requirements, and con- ductor thickness requirements. Some of these standards are now published in Chinese and German. Figure 1: IPC standards.