PCB Cavities – Registration, Bonding Bleed Outs, Shallow Routing

Common Issues / Saturn Solutions

Board fabricators who have developed specific cavity niche absorb supplier’s entire overhead via the piece price. SEC remains a production PCB supplier with a strong focus on prototyping through production of advanced technologies. However, our facility is also constantly processing higher volumes of standard technology PCBs. As a result, our overhead is spread over a larger number of production panels and projects, allowing us to charge a fair and reasonable price to our customers that is often not indicative of the high level of technology in the products we produce.

Since cavity PCBs often require sequential lamination steps, registration often becomes difficult to predict / achieve. We have had years of experience in fabricating cavity boards and have models set up based on the number of laminations, size of cutouts, and types of materials. Further, we have created custom and proprietary tooling systems to hold material in place and insure the registration of the cutout layer to the prepreg surrounding it.

Because of our experience with multiple varieties of cavity boards, we have models set up to most accurately predict the flow of bonding material so that it can be machined out to optimal dimensions.

Most mechanical depth-controlled routers cannot hold Z-axis tolerance less than 5-10 mils. This prevents cavities from being less than 5 mils in height. To address this issue, we have purchased and installed an Excellon Cobra LVD CO2 / UV laser system. Using a combination of both lasers, we are able to machine out cover material to cavities less than 5 mils in height without damaging the layer to be exposed.