Programmable bed-of-nails test access jigs

A bed-of-nails assembly for use in a programmable bed-of-nails test access jig, and including

• a framework,
• a multiplicity of pins carried by the framework and positioned on a suitable grid, each pin being mounted for longitudinal movement between a first, in contact, position and a second, out of contact, position,
• pin displacement means associated with each pin, for urging the pin to move between the two positions, and
• displacement control means associated with each pin, for controlling the pin's movement when urged by the displacement means,
• wherein:
• each pin has its own, individual, displacement control means, functionally separate from the control means of any other pin;
• each individual pin displacement control means utilizes the electro rheological effect available from an electro rheological fluid to regulate pin movement;
• and
• the framework is a rigid frame in which the pins can be mounted for longitudinal sliding movement, and consists of a rectangular base plate supporting columns themselves carrying an apertured upper guideplate which locates the pins while allowing them to slide up and down.

A bed-of-nails assembly for use in a programmable bed-of-nails test access jig, and including

• a framework,
• a multiplicity of pins carried by the framework and positioned on a suitable grid, each pin being mounted for longitudinal movement between a first, in contact, position and a second, out of contact, position,
• pin displacement means associated with each pin, for urging the pin to move between the two positions, and
• displacement control means associated with each pin, for controlling the pin's movement when urged by the displacement means,
• wherein:
• each pin has its own, individual, displacement control means, functionally separate from the control means of any other pin;
• each individual pin displacement control means utilizes the electro rheological effect available from an electro rheological fluid to regulate pin movement;
• and
• the pin displacement means is in part combined with the displacement control means, to form a combination means which both moves, and controls the movement of, each pin against a restoring force provided by a spring connecting the pin to a spacially-fixed portion of a pin-supporting framework, and wherein the displacement means includes a platen that is moved to move the pins.

A bed-of-nails assembly for use in a programmable bed-of-nails test access jig, and including

• a framework,
• a multiplicity of pins carried by the framework and positioned on a suitable grid, each pin being mounted for longitudinal movement between a first, in contact, position and a second, out of contact, position,
• pin displacement means associated with each pin, for urging the pin to move between the two positions, and
• displacement control means associated with each pin, for controlling the pin's movement when urged by the displacement means,
• wherein:
• each pin has its own, individual, displacement control means, functionally separate from the control means of any other pin;
• each individual pin displacement control means utilizes the electro rheological effect available from an electro rheological fluid to regulate pin movement;
• and
• in order to retain the electro rheological fluid in place, the complete assembly is immersed in a tank of the electro rheological fluid such that control mechanisms are below the level of the fluid but the contact portions of the pins are above the level of the fluid.

A bed-of-nails assembly, comprising:

• a tank to contain an electro rheologial fluid;
• a conductive block having a plurality of bores therein, the bores being arranged in a grid pattern;
• means for mounting the block in the tank so that the fluid enters the bores;
• a plurality of pins, each extending into a respective bore and being slidable with respect to the block between first and second positions;
• and
• means for selectively immobilizing predetermined pins with respect to the block by establishing an electric field through the fluid in the respective bores.