I’ve been working in the electronics product design and fabrication industry for 18 years, and over that time I’ve seen a lot of technology evolve. The resounding issue that occurs to me every time I implement DfM or DfT techniques in a new design (I do about 130 a year) is the true lack of integration of manufacture with regard to the mechanical packaging of electronics products and overall function.
My colleagues grow weary of my incessant emoting concerning the need to move from planar PCB fabrication and subsequent tedious mechanical mounting of components, subsequent interconnection and packaging, and the disparate steps involved in final assembly of a product toward a fully intrinsic/monolithic approach – one based on techniques such as those used for rapid prototyping of mechanical parts, similar to fused deposition modeling (FDM), whereby a device is a true intrinsic unit basically grown from the various materials required for form and function.
For example, instead of purchasing individual components such as tantalum capacitors, one merely purchases the raw tantalum compounds, licenses the fabrication formula from, say, Kemet and integrates this into what I describe as a “liquid chain,” one in which all materials in their raw form are combined on a molecular level to grow the desired product. This includes all the semiconductors/conductors, other passives, displays, and so on, which are enveloped in the housing materials. As in FDM and stereolithography (SLA), this could be a layered process combined with other processes analogous to those now used in pure semiconductor fabrication.
I use tantalum capacitors as an example because, a few years ago, there was what many trade publications deemed “a shortage of tantalum capacitors” that was incorrectly attributed to a shortage of tantalum. I knew some people associated with the Kemet factory in North Carolina and called one up, mentioning what I had read. He unequivocally stated that his facility currently had plenty of tantalum material in storage bins, the issue being one where he was unable to get the computer-controlled machinery required to make the actual parts. I jokingly suggested that it might be possible that the manufacturer of this specialized equipment wasn’t able to allocate enough tantalum caps from their distributor/supplier, as they were a bit of a niche buyer. Long silence on the other end of the phone followed.
Another issue is that if you look at the amount of material waste in just packaging printed circuit board components for shipment and delivery to EMS facilities for use on automated pick-and-place machines, the advantage of a monolithic approach is very apparent. Just look at any TI datasheet; at least three pages are devoted to reel/tube orientation and packaging, materials that themselves have to be tooled and eventually are discarded (or hopefully recycled), enveloping more mass, process and time than the actual component fabrication itself.
A distinct advantage in striving toward monolithic methods is the apparent advantage in high-speed and RF/wireless design, where as a designer, I now can use a 3D space for interconnection of controlled impedance waveguides, instead of being limited to a simple 2D planar approach trying to fudge microstrip and stripline topologies into a working subsystem that will still be fraught with failure due to interconnect processes, thermal issues, and subsequent issues involved in using soldering processes that really haven’t changed since the early 1950s. And now with the problems created with the higher reflow temperatures required for processes needed to comply with RoHS initiatives, as outlined by Dr. Howard Johnson and others at NASA1, further refinement of current production methods is just simply putting a Band-aid on a broken leg.
With some modification, current EDA and parametric mechanical software tools could be tailored to provide post-processing for these fabrication techniques, but with considerable advantages over the current methodology that relies on distinct and discrete fabrication steps – chip/passive component fabrication, PCB fabrication, mechanical tooling and fabrication – resulting in a much tighter, more efficient production process with a significant decrease in environmental impact, less waste, and much higher yields.
Imagine your cellphone as being a single block of function, with a minimum of custom components, replacing all mechanical actuation with touchscreens (as is already being done), with no need to use all these secondary operations for sub-assemblies. This is what we need to strive for.
We’re heading toward another “tyranny of numbers,” similar to the one Jack Kilby faced when presented with silicon micro modules, a situation that led him to design the first monolithic IC chip.
1. Howard Johnson, “Rolling Back the Lead-Free Initiative,” High-Speed Digital Design Online Newsletter, vol. 10, no. 1, sigcon.com/Pubs/news/10_01.htm.