The Occam Files - No. 4

Building Electronic Assemblies in Reverse

The present day electronics manufacturing industry operates on a well-established protocol, which has been decades in the making. Having a basic set of expectations about how things are done has been a key factor in creating a sense of unity and harmony within an industry which is now global in nearly every aspect from design to manufacture. Various standards bodies for electronics which were once largely national bodies (The IPC, ANSI, ASTM, the EIA and others) have become global in terms of the scope of their work and influence. This does not mean that all other national standards bodies have capitulated, Japan, Germany, Russia and other nations continue to promulgate standards for workmanship, performance and reliability. However there has been an ongoing effort to try and make sure that nations do not create standards which are exclusionary to international competitors, especially in a global marketplace. It is not an easy task.  The IEC (International Electrotechnical Commission), for instance, is one body which has long attempted to harmonize the process but because there are so many different vested interests in what the standards say and how they are distributed (yes, there is money to be made in publishing standards) the process can be painstakingly slow with standards lagging years behind the curve of technology.

One troubling result of this slow pace of reaching consensus on international standards is that there are new technologies being proposed and developed that do not have any real standards for designing or manufacturing even though they arguably hold greater promise for the future than current incumbent approaches. One such technology SAFE is technology  (those who have been following this series of articles will know that acronym SAFE stands for Solderless Assembly For Electronics)  which is fundamentally the end product of the Occam Process and the subject of this series.

So what makes the Occam Process so different? It is actually quite simple to explain but curiously it seems not so easy for designers and engineers to grasp. The foundational idea of Occam is to, as the title of this article clearly states, make electronics backwards, that is, reverse the manufacturing process...

To explain that in simplest terms, one must first appreciate that the electronics industry has been for many decades making printed circuit boards and then joining components of seemingly endless different types in terms of form, shape, size and lead termination shapes and pitches to the PCBs using solder. In contrast, the Occam Process proposes that the designer creates a “component board” and then build up the circuits upon them using the same basic processes as those used for making traditional PCBs. Note that the order of the processes is reversed and that the circuit building process follows the secure placement of components and their encapsulation by one of many different means. The total number of process, cleaning and inspection steps required for manufacturing such assemblies is significantly reduced. The high temperature and often damaging soldering process itself requires numerous steps and the preparation of both components and PCBs requires many steps as well, exclusive of their basic manufacturing.

Unfortunately, I cannot post images in the text so I am providing a link here to my book at the end of this paragraph where the reader can find a more detail of the process with graphics and images that help the reader understand. Solerless Assembly For Electronics

Soldering is a temperamental process as anyone who has ever engaged in the process can tell you. It also requires a challenging post solder cleaning process to remove flux from the tight spaces under components. There are myriad things that can, and often do go wrong with the solder process. It has become even more temperamental since the introduction of surface mount technology and high temperature lead-free soldering. In today’s environment “rework and repair” to address the shortcomings of the soldering process and been turned into virtual profit centers to deal with the inherent limitations of the soldering process.  

If the reader questions the many problems associated with the soldering process, they are invited to do an online search for “soldering defects”… actually don’t bother I just did so.  For “soldering defects” (in quotes as shown to make sure the subject search wording was exactly as written) there were 18,220 hits on Google, for “soldering problems” the number was 16,800, for “solder stencils” the number is 15,400, for “solder paste inspection”  the number was a whopping 83,000…. Any questions?

Soldering is not easy nor is it reliable. By far, the vast majority of electronic product failures can be traced to a solder joint. I have never found anyone with industry knowledge willing to take an opposing position on that simple statement of fact…

In fairness, I do not want to completely disparage solder technology. As I said in an earlier article, tin-lead solder (especially eutectic 63Sn/37Pb solder) has a long history of success because it is much easier to manage and control (there are only 3,190 hits for "eutectic solder 63/37"). On the other hand do a Google search of “lead-free solder alloy” and there are 78,600 hits. The world of lead-free solder is complex and very intimidating and there is a seemingly endless number of alloys being offered as solutions, each requiring its own special processing characterization.  

By building electronic assemblies in reverse (i.e. building a component board or assembly with the component terminations facing away from their carrier and then plating the circuits, microvias and all component termination interconnections in copper) the major point of failure in electronics, the solder joint, is eliminated. There are a host of intrinsic benefits in manufacturing as well including ability to design smaller assemblies requiring fewer circuit layers. Bypassing solder eliminates concerns about component and substrate thermal damage and opens the doors to a wider variety of prospective materials better in almost every metric from cost and performance to thermal management and dimensional stability.

No doubt there will be many questions and objections to the idea and among the first are always “What about this type of component” and “What about rework and repair” The simple answer to the first question is that the process does not have to be used for every type of current component type. It will take some time for component designers to see the potential and begin to think and design in new ways. They just need to grasp the potential. I am highly confident in the community’s collective creative genius and ability to think outside the box that constrains the industry’s progress to a better way.

The answer to the second question is actually contained in another question: “Why are we reworking and repairing electronic assemblies?” That answer is also contained in the foregoing discussion of the many well-known limitations of the soldering process.  

To end our dependence on rework and repair, we must first use the right processes and then execute those processes with care. Given all the time wasted on arguably useless steps in the solder process, there is plenty of time to “do the right things, right”

Obviously a good number of readers will be incredulous to the suggestions and assertions made here and will likely have many questions. I will try to anticipate and answer as many as I can as this series continues and will speak to the numerous benefits that await those who dare to think beyond the surface...

Next time – Component recommendations for the Occam Process