Can High Density Interconnects Withstand Extreme Temperatures?

High Density Interconnects

High density interconnect, or HDI, is a printed circuit board design technology that helps manufacturers fit more components into smaller spaces without sacrificing performance. It’s a process that starts with a carefully conceived board layer stackup configuration, then enables designers to place components closer together and conduct routing into the inner layers of the board using microvias and/or blind or buried vias. This reduces spacing constraints between components, allows more intricate designs to be completed, and offers one of the shortest ways to bypass capacitors for high-frequency designs.

In the PCB industry, there’s a constant need to push the boundaries of what can be done in a small package. In order to do so, engineers need to create new technologies and methods to help shrink the size of a circuit board. The result is that PCBs are getting smaller and smaller, and as a consequence the amount of work that needs to be done on a given PCB has increased exponentially. To meet this demand, engineers need a way to reduce the size of the interconnections on a PCB without affecting performance. That’s where the need for high-density interconnect came about.

A high density interconnect PCB can be fabricated using several different methods, but most involve depositing a photoresist pattern on the top of a laminate and then etching away the resist to leave a conductor pattern. Then, vias can be drilled using either laser or mechanical means and then metallized to form a continuous conductive path across the PCB. The next step is to build up layers in multiple lamination cycles before processing the outer layers. This enables higher layer counts, lower weight and cost, and a more compact PCB.

Can High Density Interconnects Withstand Extreme Temperatures?

To ensure that the high-density interconnect PCBs you manufacture can withstand extreme temperatures, it’s important to perform extensive tests on them. This includes thermal cycling, microvia testing and CCA (conductor acoustic fatigue) testing. The results of these tests can reveal any issues with the high-density interconnect and identify any issues that may occur during assembly.

The most common problem is excessive copper delamination, which can cause a loss of conductivity and eventually lead to premature failure. To prevent this, manufacturers must use a copper paste with the right consistency and viscosity to minimize copper delamination and ensure a strong bond between the copper foil and the surface of the PCB.

Other potential issues with the high-density interconnect include improperly matched metals and soldering techniques. To avoid these issues, manufacturers must always use the appropriate materials for the job at hand and follow best practices for soldering, reflow and cleaning.

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