3D Assembly Processes: A Look at Today and Tomorrow

Estimated reading time: 9 minutes

Figure 12: Molded interconnect device⁴.

3D Structural Electronics

3D plastic printing and 3D metal printing technologies exist now to print out plastic or metal parts based on CAD data, without any tooling involved.

Taking the 3D printing process one step further, researchers in Universities are looking to combine additive manufacturing and direct printing technologies to create 3D structural electronics.

Figure 13: 3D structural electronics⁵.

What will it take to go to 3D?

As we venture from 2D into 3D assembly, the infrastructure established for design and manufacturing of 2D assembly needs to be upgraded to handle 3D. There is currently no known CAD layout program that can handle a PCBA layout in 3D. Deposit of solder paste onto 3D surfaces need to be developed. Placing SMT components onto 3D surfaces, similar to current processes for 2D, requires development from the SMT machine supplier. The placement involves not only the machine itself, but the associated software to generate 3D placement programs similar to current processes for 2D. Automated inspection for 3D assembly needs to be developed. This includes visual and x-ray capabilities.

Summary

In the past, to achieve a 3D assembly at the PCBA level, we used connectors or various assembly methods to perform B2B or B2F connection. To reduce component count on the PCB, we can use buried capacitance or as it currently evolves to embedded passives or actives to spare valuable board space.

From the assembly level, we look at PoP and cavity assembly in finer detail. PoP allows stacking of two components that will occupy only space for one component on the PCBA. Cavity assembly allows a reduction of thickness by recessing components below the top layer of the PCB.

Looking toward the future, we look at molded interconnect device and 3D structural electronics. There are many challenges, both in design of 3D circuitry, and the manufacturing process required for 3D.

Reference

1. Courtesy: Harting har-flex PCB connectors

2. Courtesy: KSG

3. Courtesy: Cambridge PCB

4. Courtesy: LPKF, Harting AG

5. Courtesy: Keck Center, University of Texas at El Paso

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