What are Solderless Compression Mount Connectors?

Solderless Compression Mount Technology is a contact technology used to mount electromechanical components like connectors, switches test adapters for semiconductors etc. onto printed circuit boards (PCB). In this mounting technique, the electrical contact is established via compression of the two contact faces by screwing the component to the PCB, hence eliminating the need for a soldering process to mount the components onto the board.

Components mounted using the solderless compression mount process (usually connectors) have pre-compressed spring contacts that are pressed onto a gold plated contact pad on the PCB board. These connectors have flanges with holes for predefined screws that are bolted with a predefined screw force achieved using precise screwdrivers. There is also usually a metallic stiffener plate screwed from the other side of the PCB along with the connector to avoid stress and distortion on the PCB board.

Solderless Compression mount technology has several advantages over other interconnect techniques like the commonly used press-fit or screw-on. Solderless compression mount connectors provide significantly improved application performance compared to press-fit/screw-on technology in the areas of high-speed data transmission, flexibility during PCB design and reliability:

1. Signal integrity at High-Speed data transmission:

In press-fit mounting contacting of all signal layers is done using plated through holes. These through-hole contacts create interference and stub effects that affect fast signal edges or high-frequency signals.

In solderless compression mount technology, the different PCB signal layers are contacted using micro-vias which are small wells in a PCB board that are plated with conductive materials like copper on the inside and also have a conductive plate on the top. They eliminate the need for large through-holes and blind vias, thus resulting in considerably less interference and excellent impedance characteristics enabling high-speed data transmission.

2. Routing Flexibility

Routing of connectors on the board or backplane is easier with solderless compression mounting, which is also made possible due to micro-vias (blind vias and buried vias). These miniaturized contacts between the PCB layers require only minimum space compared to the large diameter of the press-fit drill holes. It also leaves more space on the board to create more routing tracks and even vertical routing tracks which is not possible at all where press-fit technology is used (as shown in Image).

Comparison of Routing Tracks with press-fit through-holes and solderless compression mount micro-vias

The better board routing capabilities also bring cost savings, with the number of PCB layers cut down by approximately one-third. This gives an estimated total cost reduction of up to 20% when using solderless PCB compression mount instead of press-fit technology.

3. Reliable Connection

Solderless Compression mounts also have advantages pertaining to the assembly of the board on which it is to used. It enables connectors to be easily screwed onto the carrier board or the backplane via an easy assembly process. This is also advantageous for repair or field service work in particular because connectors can just be unscrewed and replaced with a new one. Press-fit technology does not provide this advantage.

Due to the above-mentioned advantages of solderless compression mount technology compared to conventional press-fit technology, it is assumed that it will become the more widely accepted mounting process in the next few years, especially in the telecommunication market.