Electronic devices nowadays offer higher functionality in increasingly smaller sizes. They do this by using larger numbers of small size components with higher PCB densities. Surface Mount Technology or SMT offers very small components, and High-Density Interconnect or HDI technology provides the high density for PCBs.

Sun&Lynn metal core PCB factory makes PCBs with HDI technology for creating very thin trace width/spacing. We do this by using the modified Semi-Additive Process or ASAP. We also use microvias as these play a critical role in increasing the routing density of our HDI boards—use of microvias opens wider routing channels.

With mSAP we can create traces down to 3 mil (0.075 mm) width. Using microvias allows us to use wider routing channels, thereby adding more traces than we could in between regular adjacent through-hole vias.

Although we can drill via holes of diameter 6 mil (0.15 mm) with mechanical drill bits, the tooling cost increases significantly as the thin drill-bits snap very easily, and need frequent replacement. With laser drilling we have overcome this problem, while at the same time we can drill via holes with diameter lower than 6 mil.

Today, laser via technology is a popular method for drilling small via holes, also known as microvia holes. We use infrared and ultraviolet wavelength lasers for drilling in HDI PCBs. For drilling, we program the laser beam for fluence size and energy. Low-fluence beams can drill through organic material but leaves metals undamaged. To cut through metal and glass, we use high-fluence beams. While low-fluence beams require beams of 4-14 mil (0.1-0.35 mm) diameter, high-fluence beams require beams of about 1 mil (0.02 mm) diameter.