As the medical device industry continues its quest for less invasive implantable devices engineers and manufacturers for contract medical electronics are responding with advanced production methods such as advanced electronic bare-die manufacturing. In addition, Chip-on-Board (COB), Flip-Chip (FC) and 3D Chip Scale Packages (3DCSP) are used more routinely in conjunction with flexible and flex-rigid printed circuit board (PCB) designs. These techniques make it possible to produce tiny devices such as neuro-stimulators, cochlear implants and “completely in the canal” hearing aids.

Aluminum and gold wires should have diameters of 17 to 30 µm. Those are the parameters for our technology. The FC method connects IC chips to external circuitry with solder bumps, which are deposited on the chip pads on the top side of a wafer. To mount the chip to a circuit board, the chip is flipped over so its top side faces down, its pads align with matching pads on an external circuit, and then the solder is flowed to complete the interconnect. 3D chip scale packaging refers to the vertical (z-axis) stacking of multiple dies within a package, or multiple packages, using specialized substrates and interconnects.

Engineers and manufacturing personnel involved in the design, development, and assembly of these types of devices require a detailed knowledge of electronic circuit design, along with an intimate knowledge of mechanical design and material science. Anticipating what happens to a circuit board that gets folded, or determining the metallization required on the PCB pads to ensure the reliable attachment of gold wires one-third the diameter of a human hair, are skills that cannot be learned in most college engineering programs.

While most engineering students graduate with a basic knowledge of PCB layout, performing a layout in more than one dimension is a skill that takes time to develop. That time extends further when learning the intricacies of designing a three-dimensional, flex-ridged board.

Professor Steven Saliterman at the University of Minnesota and others of like mind have recognized a need for additional education and training. In his book, BioMEMS and Medical Microdevices, Saliterman discusses techniques for bare-die manufacturing and circuit miniaturization. While nothing replaces hands-on experience and working under the watchful eye of someone experienced in circuit miniaturization techniques, professors such as Saliterman and books such as his can at least expose students to advanced electronic circuit designs.

The University of Kentucky also has an excellent program with equipment that mirrors real world contract manufacturing. Here the theoretical and hands-on activity develop students who can get up to speed and tackle designs of miniaturized electronic packages for medical devices.

For now, there aren't enough academic institutions mirroring the efforts of the University of Minnesota and the University of Kentucky. For that to change, manufacturers of medical devices, medical electronics, and academia must work together to develop programs that will prepare students to design and develop miniaturized implantable products that speed recovery and reduce cost of care.