RJ45 Press Fit Connectors (Compliant Pin)

 

Xmultiple's Engineering Department


Compliant pin technology is a solder-free assembly process. The press fit pins are inserted to a ˇ§compliantˇ¨ section of the board that is slightly larger than the plated PCB hole. When the pin is inserted, the compliant section is compressed and this is what provides the connection between the PCB and the pin.


Plated-through-hole diameters for solderless press-fit connectors.

Solderless press-fit connectors for insertion into plated through holes has become a new method of attaching connectors.

Information regarding the specified size of plated through-holes for this process is listed below.

1. Connectors with compliant pins work with industry standard hole tolerances of ˇÓ.003ˇ¨. Xmultiple provides the drill hole size which is specified before plating in order to center the finished hole size within the ˇÓ.003ˇ¨ tolerance. As an example, to achieve a finished hole diameter of .040ˇÓ.003ˇ¨ the plating would reduce the hole diameter by .0035ˇ¨.

The drill hole size for press fit connectors is important to note before plating. A square, pent. or hex. press-fit design uses the thickness of the copper in the plated through-hole for the press-fit interference. The drill size should be slightly larger than the diameter of the points of the press-fit feature.

Tin-plating thickness in the holes is not critical to the press-fit operation. The copper material of the printed circuit board is soft enough to be displaced by the pins.

Xmultiple press fit connectors have barbs as their press-fit feature. These are designed for pressing into molded housings or drilled holes (not plated through) in circuit boards. Drilled holes can be specified with a ˇÓ.001ˇ¨ tolerance.

During the assembly process there are steps you should take. When pressing gold plated pins into gold plated boards or tin pins into tinned boards, there is ˇ§cold
weldingˇ¨ of the similar metals in contact. This gives rise to extremely high insertion forces that could damage the board or the connector. You must use a lubricant in the holes during the press fit insertion operation to dramatically reduce ˇ§cold weldingˇ¨. A contact lubricant such as OS-138 is recommended. After the insertion process the boards should be washed.

It should be noted that "cold welding" can occur even if lubricant is use so heat can be generated in the holes during the insertion process. When the insertion process is performed it would be at a slow rate to minimize heat which can damage a printed circuit board.

 

 

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