Dictionary of Engineering Terms
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Compliant Pin Description

Compliant pin technology is a press-fit, solder-free process used to interconnect pins and tabs to a PCB. The mechanical and electrical interfaces between the product and PCB are made by a spring-like compliant pin and a plated thru-hole [via].

Compliant Pin and PCB via connection through board layers
Double Sided Board with Compliant pins

A press-fit connection between a printed circuit board [PCB] drilled through hole and a connector pin is made by pressing an over-sized pin into the drilled thru-hole of the PCB. The cross section of the pin is greater than the diameter of the hole. This results in an overlapping of material at the pin and drilled through hole, which must be taken up by deformation of either the pin or the hole. A compliant pin will deform as it's being inserted into the via, a non-compliant will deform the via.

Advantages of Compliant pins over non-compliant pins:
1. Because the press-fit zone of the pin compresses, the plating of the drilled through hole is saved from possible destruction of the through connection to the circuit paths.
2. The compliant pin allows a bigger tolerance of through plated holes.
3. Reduction of insertion force.
4. Multiple pressing of contacts into the same hole is possible.
... Compliant pins require plated-through holes.

Refer to MIL-STD-2166, which has been cancelled with no replacement in 1999

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Also refer to the dictionary of PWB Terms
More Printed Wiring Board Information and specifications.

Circuit Board Design Hint; Connectors are produced in both 'normal' pin and compliant pin variants. So the pin holes need to be sized for the correct variation of the pin style. If the board is layed-out for normal sized pins the via will not accept a compliant pin. However; if the board is designed for compliant pin, a standard pin may still be inserted and then soldered. Also, a pin hole may be over-sized so that a compliant pin may be installed without deforming and soldered into the hole. Of course neither of these last two approaches are recommended, and are really fixes to allows parts on-hand to be used.

Circuit Board Layout Note; Because these compliant pin connectors need to be accurately installed with some force they may require a tool for installation. The tool forces one side of the connector into the board while a second accepts and aligns the pins on the reverse side of the board. Both sections of the tool are aligned with each other via tooling holes in the board. These additional tooling holes extend out beyond the connector body and need to be accounted for during circuit layout.

Circuit Board Re-Work Note; because the pins of the connector are over-sized and designed to deform when inserted into the PWB they may not be reused. Even if it were possible to remove a compliant pin connector with all its pins still attached to the body of the component, the pins are still badly deformed and will no longer act as a compliant pin. In most cases a compliant pin connector may be removed from the PWB with out damaging the pin vias. So another compliant pin connector may be re-installed, after the damaged connector is removed. However because the male compliant pin puts pressure on the via the pin may only be removed and reinserted a set number of times, perhaps 3 times.

MIL-STD-2166 defined three types of Compliant pins;
Type I: Compliant pins which are not individually removable from the plated-through hole or the connector when the connector is installed on the Printed Wiring Board [PWB].
Type II: Compliant pins which are individually removable from the plated-through hole. The pins may be used with or without a connector housing, but when used with a housing shall not depend on the housing for retention.
Type III: Compliant pins which are individually removable from the plated-through hole. The compliant pin shall be installed in a housing and shall be partially depend on the housing for retention in the plated-through hole.

PC motherboard

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