Hybrid/MCM Design, Coming of Age
Tom Dlouhy, C.I.D.
CAD Design Software
San Jose, California 95110
ABSTRACT
In the early days, Hybrid/MCM layout was traditionally done with a rough design drawing done on paper or mylar and the circuitry transferred to rubylith, which was cut at a 10X, 20X or even 40X scale and then photo-reduced to a 1:1 scale. While this sufficed for simple designs of the day, future designs would only become more complex and more confined. The photo-reductions lacked the accuracy required for drastically reduced trace widths and designs that required closely controlled spread and shrink factors. This process was quite costly, resulting in initial designs and design changes having to be carefully checked and re-checked prior to getting photo-reductions processed. The checking and re-checking would also add to the cost of the process.
Real Hybrid/MCM layout software was quite a way down the road and the early, available EDA software was only geared toward PCB layout and that dealt with digital design at best. As a stopgap measure, many turned to using CAD software and translators to design at 1:1 and achieve direct result photo-plot image films.
While this eliminated the photo-reduction process of the circuitry images and its costs and inherent problems, it still did nothing to achieve what the PCB layout world was taking advantage of; this being schematic capture, LVS (layout vs. schematic), and DRC (design rule checking). Still the Hybrid/MCM industry trudged on with manual node checking usually involving at least 2 people simultaneously, one to read the schematic or node list and one to check the layout design. DRC was also done manually and this at times could involve an additional third person, so that another set of eyes was checking the design.
In order to dramatically improve reliability, yields, and substantially decrease costs and design-time-to-product for Hybrid/MCM technologies, a true Hybrid/MCM design process is required which integrates the design, optimization, verification, manufacturing, and assembly processes into a seamless system. This design and collaboration system provides data access by all related departments in order to optimize the design for maximum performance as well as highest yield and fastest time-to-product. Manufacturing, engineering, and assembly departments are able to input specific design and manufacturing parameters during the design and layout process. The layout is completed and assembly parameters are verified and optimized during the design process. The resultant design has already been optimized for manufacturing when it arrives in production, thereby eliminating many of the problems prone in the hybrid design and assembly process today.
This paper explains the desired features and benefits of an ideal Hybrid/MCM design system.
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