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Solderless Spring/Pin Connection

IP.com Disclosure Number: IPCOM000037968D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Palmieri, JA: AUTHOR [+3]

Abstract

Spring pins are commonly used in multi-layered printed circuit boards (PCBs) to establish electrical connection between a plated through hole (PTH) and the pin. The pin has a shoulder which acts as a spring to form a gas-tight joint between the PTH wall and the pin. A layer of tin lead in the PTH, pin, or both, is used as a lubricant because insertion forces and friction are high (upward of 30 lbs.). Nitinol (NiTi Naval Ordnance Laboratory), because of its "remembering" property, accomplishes the same task but eliminates the high insertion force in the manner described in the following.

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Solderless Spring/Pin Connection

Spring pins are commonly used in multi-layered printed circuit boards (PCBs) to establish electrical connection between a plated through hole (PTH) and the pin. The pin has a shoulder which acts as a spring to form a gas-tight joint between the PTH wall and the pin. A layer of tin lead in the PTH, pin, or both, is used as a lubricant because insertion forces and friction are high (upward of 30 lbs.). Nitinol (NiTi Naval Ordnance Laboratory), because of its "remembering" property, accomplishes the same task but eliminates the high insertion force in the manner described in the following.

The pin is formed as a spring in the shoulder portion (Fig. 1) and is then over-stretched (Fig. 2). This decreases the diameter of the pin and the pin is positioned in the PTH of the PCB. The pin is then heated (current, IR, oil bath) to its triggering temperature where it returns to its original shape, i.e., expands and forms a gas-tight joint. The sequence of events is shown in Figs. 1 through 3.

The pin can be removed in three different ways: 1) By pulling at both ends of the pin, the pin's diameter is decreased to allow the pin to be removed, 2) By clamping one end of the pin and twisting the other end, the pin coil is wound more tightly, thus, also reducing the spring's diameter to allow removal, and 3) By pulling on one end of the pin until it is withdrawn.

Disclosed anonymously.

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