Introduction to the Design Challenge of Engineering Miniature Circuits

Posted on Monday, March 12, 2018
Introduction to the Design Challenge of Engineering Miniature Circuits

Though a device designer may be an expert in knowing the specific technology needed in a device, this expertise does not necessarily translate into knowing how to design and produce the necessary circuitry for the size, reliability, and mass production requirements that are critical to the new device’s success. Here are 3 quick tips to keep in mind when approaching the design of an ultra-small circuit.

1. Don’t assume that just because it works in the graduate lab it will work at volume

It’s common practice for device companies to collaborate with advanced medical science and engineering teams at Universities and Research Institutes to develop next-generation technologies and devices. But, a common pitfall of this practice is that there’s a presumption that the prototype manufacturing tools and equipment used in a University lab—that may have led to working models and small volumes of a circuit—are the same as those required to produce a circuit at high volume. (This is not limited to University research, by-the-way. Expert designers at major brands often make similar errors in their own labs). To avoid this pitfall, connect with a thin-film manufacturing partner early in the design phase and prevent design/development from going down a road that will later require redesign when approaching manufacturing at volume. 

2. Avoid Over-specification

As any engineering team can relate, it’s not a designer’s nature to leave anything on the table in regards to performance. “If it can be done, it should be done,” is the common underlying mantra. But when a particular performance parameter is overvalued, or there isn’t a precise understanding of a nominal range for a parameter, the result is numerous redesigns, potentially costly exotic materials, and manufacturing trials that will ultimately increase costs and time-to-market. Ensuring that features and their parameters are fully vetted by the team, and ultimately by your circuit manufacturing partner who’s been there before, is crucial.

Note: Exotic materials are typically substantially higher in cost, and there may be a limit to how, or if, they can be processed by a fab. Some metals are also unable to be processed in the presence of others, as certain metals and processing agents may interact chemically. For example, platinum can only be used on a gold circuit if it’s added to the metal stack during the optimal process step. This is a result of the platinum metal etchant also etching all other metal types. This is somewhat similar to a solder hierarchy used in PCB and PCBA manufacturing.

3. Avoid Under-Specification

The flip side of over-specification, of course, is not considering the various must-haves before transferring your prototype files to your thin film circuit manufacturing partner. This could be anything from bonding bumps, micro-circuit stiffeners, and extremely dense circuit patterns. All of which, need to be considered during the design stage to avoid unfortunate redesign and revalidation. 

To learn more, download our Tech Brief: "Design-for-Manufacturability (DFM) Tips for Miniature Biomedical Sensor Circuits"