SMD Prototyping Without Soldering

Many electronic components are now so inexpensive that they are considered to be disposable. But just because it makes sense economically to throw away perfectly good parts does not necessarily mean that we should do so. This is a consideration that often comes up in design prototyping, where new versions of devices are rapidly produced to test new functions. The fact of the matter is that modern SMD components take a lot of time to desolder, so the effort that goes into salvaging a part may simply not be worth it.

Back in the days when through-hole components were typically used in electronics, one could prototype with a breadboard and easily reuse components by simply lifting them off of the board when they were finished. Without such a system for SMD components, many of them are likely to wind up as e-waste. Given that United Nations estimates show that over 60 million tons of e-waste are already being generated each year, this is a pretty big problem. E-waste, which contains a number of toxic chemicals, is certainly not something we want filling up our landfills.

Some creative researchers at the University of Maryland, College Park have come up with something like a breadboard for the modern age. Their system, called SolderlessPCB, makes it possible to attach SMD components to a PCB — as the name implies — without soldering. SolderlessPCB utilizes custom housings that securely attach components to a PCB using bolts. The process can be reversed, and the pristine components can be recovered, by simply loosening the bolts and removing the housing.

The approach involves fabricating a custom, 3D-printed housing that aligns with a PCB design. The housing contains a number of cavities, one for each component that is to be mated with the board. The components could range from simple two-terminal devices like resistors or capacitors to any number of integrated circuit packages and even non-standard components like battery holders. Each of these component styles presents unique challenges in making a good electrical connection, which the team dealt with in a variety of ways. Two-terminal components, for example, tend to have some degree of variance in their height. For these cases, flexible tabs were built into the cavities to ensure that sufficient pressure is applied to the device to overcome these differences in tolerance and make good contact with the PCB.

To streamline the process of designing the housings, a component library was created for Autodesk Fusion 360. A rough outline of the steps involved in using this library and creating both the housing and PCB is included on the team’s GitHub repository. When it comes time to print the housing, note that standard plastics or resins will not be sufficient due to the flexible tabs that it contains. The researchers found that a 3:2 mixture of a tough UV resin and a flexible UV resin fit the bill nicely, however.

A series of electrical and mechanical tests were conducted to assess the reliability of SolderlessPCB. It was found to maintain good electrical connections after being dropped several times, indicating that the system is well-suited for use in prototyping. There is some work that needs to be done to get going with SolderlessPCB, however, so it may not make sense when just a few design iterations will be needed. But where many versions will be tested, SolderlessPCB could save time and money, and also keep e-waste out of the landfill.