LGA compression contact repair system
AssigneeUnisys Corporation
InventorThomas P. Currie
Life of this patent
Estimating the term…
Abstract
An improved rework method and rework wiring structure for repairing and reworking multilayer printed circuit boards utilizing land grid array (LGA) compression contact pads are described. The repair method includes the steps of locating a compression contact pad to be rewired, removing the identified pad, installing a repair wire through a via hole in a multilayer printed circuit board, and forming a replacement compression contact pad on the end of the repair wire and positioning it in place of the removed contact pad. Once thus installed, the method includes the step of connecting the other end of the repair wire to a corrected circuit interconnection point.
Claims14
In a multilayer printed circuit board having first and second surfaces;
- an array of compression contact pads arranged on said first surface to electrically contact associated contacts on at least one integrated circuit;
- a plurality of electrical wiring nets;
- a plurality of plated-through holes extending through said printed circuit board between first said and second surface, selected ones of said plurality of plated-through holes in electrical contact with associated ones of said plurality of wiring nets, and each of said plurality of plated-through holes electrically connected to an associated different one of said array of compression contact pads;
- the improvement comprising;
- a repair wire having a first end portion formed in the shape of a compression contact pad and positioned on and affixed to said first surface of said printed circuit board to replace a removed one of said array of compression contact pads, said repair wire further having an electrical insulated board transition portion extending through the one of said plated-through holes that is associated with said removed one of said array of compression contact pads, and said repair were further having a second end portion extending beyond said second surface to make connection to a selected circuit interconnection point to repair the function of the circuit.
A method of reworking a multilayer printed circuit board having a predetermined array of compression contact pads electrically connected to respectively associated via lands on plated-through barrels on a first surface of the printed circuit board, each of the barrels extending through the printed circuit board to a second surface and interconnecting to predetermined wiring nets within the printed circuit board, said method comprising the steps of:
- a. identifying one of the compression contact pads requiring a changed electrical connection;
- b. removing the identified compression contact pad from the first surface;
- c. selecting a repair wire;
- d. inserting a first end of select repair wire in the barrel opening associated with the identified and removed compression contact pad until a predetermined portion of the first end is exposed beyond the first surface;
- e. shaping the end of the predetermined portion in the shape of a compression contact pad;
- f. positioning the shaped end on the first surface in a position to replace the removed identified compression contact pad;
- and
- g. affixing the positioned shaped end to the first surface.
A method of reworking a circuit connection on a multilayer printed circuit board that mounts one or more integrated circuits and having a predetermined array of compression contact pads to interconnect each integrated circuit and electrically connected to respectively associated via lands on plated-through hole barrels on a first surface of the printed circuit board, each of the barrels extending through the printed circuit board to a second surface and interconnecting to predetermined wiring nets within the printed circuit board, said method comprising the steps of:
- a. exposing the array of compression contact pads requiring circuit alteration;
- b. identifying and locating the compression contact pad to be repaired;
- c. protecting the compression contact pads adjacent to the located compression contact pad;
- d. removing the identified compression contact pad and its associated via pad and interconnecting foil;
- e. selecting a repair wire and threading it through the barrel opening associated with the identified compression contact pad;
- f. forming a replacement compression contact pad on the exposed end of the repair wire;
- g. determining whether or not special coating material for the newly formed compression contact pad is required, and if required adding the special coating material;
- h. forming and bonding the newly formed compression contact pad to the first surface of the printed circuit board;
- i. routing and connecting the repair wire to the corrected circuit connection;
- j. determining whether or not a special insulator layer is required adjacent the second surface of the printed circuit board to protect the repair wire, and if required, forming the special insulator and putting it In place;
- and
- k. reassembling the integrated circuit and related components.
Dependencies are inferred from the claim text.