Method of making an interposer sub-assembly in a printed wiring board

A process for fabricating an electronic sub-assembly comprising the steps of:

• providing a printed circuit board having a first surface and a plurality of vias terminating as electrical contacts at said surface;
• providing a contact pad at the end of each via;
• providing an area array device having a surface facing the first surface of the board, said area array device having a plurality of conductive input and output contacts on said surface;
• and
• providing a plurality of connectors to electrically interconnect the contact pads on said printed circuit board and the conductive contacts on said area array device.

A method of making a printed wiring board sub-assembly comprising:

• providing a first surface on the printed wiring board surface;
• providing one or more vias extending from the surface into the board;
• providing an electrically conductive contact pad on the first surface of the printed wiring board connected to each via;
• providing a first interposer structure having a first surface facing the surface of the printed wiring board, and a second surface, said interposer including a pattern of holes corresponding to the vias in the printed wiring board, and electrical connectors in each hole in the pattern;
• and
• joining a first end of each connector in the interposer structure to a conductive pad on the first surface of the printed wiring board using solder or paste.

A method of maintaining a fixed minimum distance between a printed wiring board and an area array device comprising:

• providing a printed wiring board having a first surface including a plurality of vias extending from said surface into the board;
• providing a plurality of electrical contacts pads on said first surface connected to each of the vias, at least some of the contact pads being offset from the corresponding vias to which the contact pads are electrically connected;
• providing a first area array device having a surface including a plurality of electrical contacts, said two surfaces spaced a fixed minimum distance from one another, and
• providing a plurality of connectors for electrically coupling the contact pads on the surface of the printed circuit board to the electrical contacts on the surface of the first area array device.

An electronic sub-assembly comprising a printed wiring board having first and second generally planar surfaces and a plurality of vias terminating in electrical contact pads on the surfaces;

• a first area array device having a generally planar surface facing the first generally planar surface of the printed wiring board and having a plurality of electrical contacts thereon;
• a plurality of connectors for electrically coupling the electrical contacts on the first surface of the printed circuit board to the electrical contacts on the surface of the first area array device, the connectors being selected from the group consisting of wadded wire contacts, metal springs, filled conductive elastomers, solder balls and hard balls;
• a first interposer separating the first surface of the printed wiring board from the surface of the first area array device a fixed minimum distance of about 3 mm, the interposer containing a pattern of holes corresponding in location to the contacts on the first surface of the printed wiring board, said connectors that couple said printed circuit board to the second area array device being positioned in said holes;
• said sub-assembly further including a second area array device having a surface including a plurality of electrical contacts for electrically coupling the second surface of the printed circuit board to the second area array device;
• a second interposer separating the second surface of the printed wiring board from the surface of the second area array device, the interposer containing a pattern of holes corresponding in location to the contacts on the second surface of the printed wiring board;
• a plurality of connectors positioned in the pattern of holes in the second interposer for electrically coupling the electrical contacts on the second surface of the printed circuit board to the electrical contacts on the surface of the second area array device;
• at least some of the electrical contacts on one or both of the generally planar surfaces of the printed wiring board comprising contact pads that are offset from the corresponding vias in the printed wiring board to which the contact pads are electrically connected;
• and
• at least some of the connectors in the holes of said interposers having a first end soldered to said contact pads and a second end compressed against the electrical contacts on the generally planar surface of the corresponding area array device.

A process for fabricating an electronic sub-assembly comprising the steps of:

• providing a printed wiring board having a first and a second generally planar surface and a plurality of vias terminating as electrical contact pads at each said surfaces;
• providing a contact pad on the surface at the end of each via;
• spacing a first area array device having a generally planar surface facing the first surface of the board a fixed minimum distance of about 3 mm from the printed wiring board, said area array device having a plurality of conductive input and output contacts on said surface, at least some of which correspond to the contact pads on the first surface of the printed wiring board;
• providing a first interposer between the printed wiring board and the first area array device, said interposer structure having first and second generally planar surfaces and containing a pattern of holes corresponding in location to the contact pads at the ends of the vias on the first surface of the printed wiring board;
• providing a plurality of connectors to electrically interconnect the contact pads on said printed circuit board and the conductive contacts on said first area array device;
• incorporating each connector into one of the holes in the first interposer structure;
• providing a second area array device having a generally planar surface facing the second surface of the printed wiring board, said second area array device having a plurality of conductive input and output contacts, at least some of which correspond to the contact pads on the second surface of the printed wiring board;
• providing a second interposer between the second surface of the printed wiring board and the second area array device, said interposer having first and second surfaces and a pattern of holes corresponding in location to the contact pads at the ends of the plated holes on the second surface of the printed circuit board and the corresponding conductive input and output contacts on the second area array device;
• incorporating electrical connectors into the holes in said second interposer;
• soldering or pasting one end of at least some of the connectors of said interposers to said contact pads and using pressure contact to join the other second end against the electrical contacts on the generally planar surface of the corresponding area array device.