Ejector Latch for Circuit Board

RTP Company joined forces with molder, Cal-Tron Corp. of Bishop, CA, to meet the material requirements for a face panel and an ejector (latch) used on a circuit board.

The applications are part of a digital loop carrier system made by Advanced Fibre Communications, Inc. (AFC) of Petaluma, CA. The circuit board forms the critical connection between phone companies and remote terminals in the field.

The face panel requires static protection due to critical wiring. In response, RTP Company research and development engineered a permanently antistatic RTP 2500 Series polycarbonate/ABS alloy. The material prevents the buildup of static charges from a normal working environment.

The specialty compound’s surface resistivity is 10¹⁰-10¹¹ ohms/sq and the static decay meets the requirement for the military specification B-81705c.

The circuit board calls for a precolored grey face panel. Because most antistatic materials would lose their inherent properties during coloring, parts are usually painted. RTP Company was able to eliminate the cost of this step by engineering a precolored grey material employing PermaStat® technology developed by RTP Company.

According to Karen Leathham, Cal-Tron operations manager, economics is a major advantage of the material. “RTP Company uniquely offers a precolored, antistatic material. This eliminates the need to paint the parts, reducing production costs,” Leatham notes. “This alone saves AFC a minimum of $250,000 a year.”

The material exhibits an un-notched impact at (1/8-in.) of 6.0 ft.lbs./in. and a flexural modulus of 0.51 x 10⁶ psi.

The ejectors are also precolored and require structural integrity. A glass-fiber reinforced RTP 1000 Series (PBT) compound provides a tough, resilient material appropriate for the wear and use of a latch.

The specialty compound exhibits a tensile strength of 7,500 psi and a flexural strength of 12,500 psi. It has a tensile modulus of 0.45 x 10⁶ psi and a flexural modulus of 0.43 x 10⁶ psi. In order to meet fire safety requirements set by most phone companies, the face panel and ejectors are both flame retardant.

Rick Girvin, purchasing manager at AFC notes, “Not only is the material excellent, the service level of RTP Company employees has been tremendous. RTP Company has taken an extra step in developing a material to meet our specific needs.”