Circuit writer

Apparatus for producing electrically conductive traces on a circuit board comprising:

• extrusion means for extruding a material that is electrically conductive after curing, hereinafter called the electrically conductive material;
• said extrusion means comprising an extrusion housing in which extrudable polymer is contained, means for applying a force to said extrudable polymer from said housing and onto a circuit board, means for monitoring rate of extrusion information, and first control means for controlling the application of force in response to said rate of extrusion information supplied by said monitoring means;
• stage means for holding said extrusion means and said circuit board in relative proximity and for producing relative motion of said extrusion means and said circuit board;
• and
• second control means for controlling said extrusion means and said stage means to cause said electrically conductive material to be extruded onto a surface of said circuit board along preselected paths to produce said traces.

A method of producing electrically conductive traces on a circuit substrate support comprising the steps of:

• extruding a first polymerizable material onto a circuit substrate support along preselected paths to form traces;
• polymerizing said first polymerizable material, said first polymerizable material being conductive after polymerization;
• applying a second polymerizable material over said support at a plurality of points along said preselected paths overlying said first polymerizable material;
• and
• polymerizing said second polymerizable material, said second polymerizable material being electrically insulative after polymerization.

A method of forming a circuit of insulated conductive traces on a substrate, the method comprising the steps of:

• (a) calibrating a stage so that positions on a substrate correspond to positions pre-programmed into a trace routing engine, the trace routing engine containing a programmed representation of the circuit;
• (b) extruding a trace onto said substrate by a first extrusion means under programmed control of the trace routing engine, said trace consisting of a first material;
• (c) hardening said trace;
• (d) layering a second material onto said hardened trace, the second material encapsulating said hardened trace;
• (e) hardening said second material;
• (f) repeating steps (b) through (e) until a cricuit determined by the trace routing engine is complete;
• and
• (g) curing the first and second materials to form the circuit of insulated conductive traces.

An insulated conductive trace on a surface of a substrate, the insulated conductive trace comprising:

• a core consisting of an extruded conductive polymer thick film, the core having a width in the range of 3 to 20 mils and a resistivity in the range of 0.1 to 0.6 ohms per inch;
• a sheath consisting of an extruded insulative polymer thick film, the sheath encapsulating the core and binding the core to said surface of said substrate;
• and
• an interfacial layer between the core and the sheath, the interfacial layer consisting of an impermeable hydrophobic polymer.

A device for extruding an extrudable material comprising:

• a storage volume for storing a quantity of an extrudable material;
• a write tip with an opening to said storage volume, said write tip for ejecting and forming said extrudable material;
• a fill passage connecting to said storage volume for supplying said extrudable material to said storage volume;
• a valve passage with an opening into said fill passage;
• a valve piston in said said valve passage urged by a spring to tend to close said opening into said fill passage;
• a supply port opening into said valve passage such that said extrudable material under pressure introduced to said supply port moved said valve piston against said spring to open said valve passage to said fill passage allowing said extrudable material to flow from said supply port through said fill passage into said storage volume;
• and
• a pressure port into said storage volume for introducing a gas under pressure to cause said extrudable material to extrude from said write tip.

A method of forming an electrical connection between two otherwise electrically isolated mounting pads, said pads having been constructed on a circuit substrate support having an electrically conductive clad layer over an electrically non-conductive support material by removing trenches through said clad layer to form said pads, comprising the steps of:

• forming an insulative roadbed between mounting pads on a circuit substrate support by extruding insulative polymerizable thick film from an orifice, said roadbed overlying a conductive clad layer between said mounting pads;
• forming a conductive trace between said mounting pads by extruding polymerizable thick film between said mounting pads, said conductive trace touching each of said conductive pads and following and overlying said insulative roadbed, said conductive trace being narrower in breadth than said insulative roadbed;
• polymerizing said polymerizable thick films, said thick film for said conductive trace being electrically conductive after polymerization;
• and
• extruding an insulative cover of polymerizable thick film over said extruded conductive trace before said polymerization step, said insulative cover together with said insulative roadbed encapsulating said conductive trace.

A circuit board for holding electrical components comprising:

• a circuit substrate support having an electrically conductive clad surface layer over a non-conductive support material;
• a plurality of conductive mounting pads on said non-conductive support material, said mounting pads being constructed by forming trenches through said electrically conductive clad surface layer to form said mounting pads;
• a plurality of extruded electrical traces between said mounting pads, said electrical traces formed of polymerizable thick film material, which becomes conductive after polymerization, over insulative roadbeds of extruded insulative polymerizable thick film material between said mounting pads and
• wherein said electrical traces are encapsulated in extruded insulative material along said roadbeds.

A method of forming an electrical connection between two otherwise electrically isolated mounting pads, said mounting pads constructed on a circuit substrate support having an electrically conductive clad layer over an electrically non-conducting support material by forming trenches through said clad layer to form said pads, comprising the steps of:

• forming a connection trench through an electrically conductive layer between trenches forming isolated mounting pads;
• extruding a trace of polymerizable material from one of said electrically isolated mounting pads to the other of said isolated mounting pads, following the path of said connecting trench, said trace being of narrower width than the width of said connecting trench, such that said trace nowhere touches said clad layer except at said isolated mounting pads;
• and
• polymerizing said polymerizable material, said polymerizable material being electrically conductive after polymerization.

A method of forming an electrical connection between two otherwise electrically isolated mounting pads formed on a circuit substrate support comprising:

• forming an electrically conductive clad layer over an electrically non-conducting support material and a non-conductive layer over said electrically conductive clad layer,
• forming trenches through said clad layer and said non-conductive layer
• filling said trenches with insulative materials by extruding insulative polymerizable thick film from an orifice into said trenches;
• extruding a trace of a second polymerizable material, which becomes conductive after polymerizing, from one of said electrically isolated mounting pads to the other of said isolated mounting pads, said trace touching the conductive materials of each of said mounting pads and overlying said non-conductive layer between said mounting pads and said insulative material filling said trenches;
• and
• polymerizing said polymerizable materials.

A circuit board for holding electrical components comprising:

• a circuit substrate support having an electrically conductive clad layer over a non-conductive support material and a non-conductive layer over said electrically conductive clad layer;
• a plurality of conductive mounting pads on said non-conductive support material, said mounting pads being formed by forming trenches through said electrically conductive clad layer and said non-conductive layer and removing said non-conductive layer from said mounting pads, said trenches filled with an extruded insulative material;
• and
• a plurality of extruded electrically conductive traces between and connecting to said mounting pads, said electrically conductive traces being formed of a polymer thick film and positioned along paths overlying said insulative material filling said trenches and overlying said non-conductive layer wherein said conductive traces are covered with a coating of extruded electrically insulative material onto said conductive traces along said paths.

A method of electrically connecting a conductive pad on one side of a circuit board having an inner conductive layer with a conductive pad on the other side of said circuit board without said electrical connection contacting said inner conductive layer, comprising the steps of:

• drilling a first hole through a circuit board, said hole penetrating conductive pads on both sides of said board and penetrating an inner conductive layer;
• extruding insulative polymerizable thick film material into said first hole from an orifice;
• drilling a second hole through said insulative plug, said second hole leaving an annulus of insulative material within said first hole;
• extruding a second polymerizable thick film material, said material being conductive after polymerization, into said second hole from an orifice such that said second material overlaps said insulative material on each side of said circuit board making contact with each said conductive pad, said second material being electrically isolated from said inner conductive layer by said annulus of insulative material;
• and
• polymerizing said second polymerizable thick film material forming an electrical connection between said pads, said second material being electrically isolated from said inner conductive layer.

A circuit board for holding electrical components comprising;

• a circuit substrate support having an inner conductive layer and a conductive pad on each side;
• a connection between said pads on opposite sides of said circuit board, said connection comprising:
• an insulative plug formed in a first hole drilled through said circuit board, said first hole penetrating conductive pads on each side of said circuit board and penetrating said inner conductive layer;
• said insulative plug formed of extruded insulative polymerizable material from an orifice into said first hole;
• a second hole drilled through said insulative plug leaving an annulus of insulative material through said circuit board;
• and
• a conductive trace through said second hole, said conductive trace formed of extruded polymerizable material which is conductive after polymerization through said second hole, making contact with said pads on opposite faces of said circuit board, said conductive trace isolated from said inner conductive layer by said annulus of insulative material.

A method of electrically connecting a conductive pad on one side of a circuit board having an inner conductive layer with a conductive pad on the other side of said circuit board without said electrical connection contacting said inner conductive layer, comprising the steps of:

• forming a slot through a circuit board, said slot penetrating conductive pads on both faces of said circuit board and penetrating an inner conductive layer;
• extruding a roadbed of insulative polymerizable thick film material along a portion of said slot from an orifice, said roadbed crossing said inner conductive layer;
• extruding a first trace of polymerizable thick film material into said slot from an orifice, said polymerizable material being conductive after polymerization, said first trace of polymerizable material having a lesser width than said roadbed for insulative material and overlying said insulative roadbed such that said first trace does not touch said inner conductive layer, said first trace touching each of said conductive pads on opposite faces of said circuit board;
• and
• polymerizing said polymerizable materials.

A circuit board for holding electrical components comprising:

• a circuit substrate support having an inner conductive layer and a conductive pad on each side;
• and
• a connection between said pad on opposite sides of said circuit board, said connection comprising;
• a slot formed through said circuit board, said slot penetrating conductive pads on each side of said circuit board and penetrating said inner conductive layer;
• an insulative roadbed in said slot, said insulative roadbed formed of extruded insulative polymerizable material, said insulative roadbed crossing said inner conductive layer of said circuit board;
• and
• an extruded trace within said slot, said trace formed of extruded polymerizable material which is conductive after polymerization in said slot, said trace making contact with said pads on opposite sides of said circuit board, said trace being isolated from said inner conductive layer of said circuit board by said insulative roadbed.

A method of forming a mounting pad for registering and attaching leads of discrete devices on a circuit substrate support comprising the steps of:

• extruding a pad of insulative polymerizable material onto an circuit substrate support:
• polymerizing said polymerizable insulative material;
• forming openings into said polymerized insulative pad, said openings for registering and mounting leads of electrical components;
• extruding polymerizable material conductive after polymerization into said openings to form conductive mounting surfaces for said leads of said electrical components;
• and
• polymerizing said conductive polymerizable material.

A polymer thick film extrusion device comprising;

• an extrusion housing including a central passage in which extrudable polymer is contained;
• a fill passage in said housing for allowing the passage of extrudable polymer from a polymer storage reservoir to said central passage;
• means for forcing said extrudable polymer from said passage and onto a circuit board
• means for monitoring the rate at which said extrudable polymer is extruded;
• and
• control means for controlling the application of force applied via said force applying means responsive to said rate of extrusion information supplied by said monitoring means.

A circuit board for holding electrical components comprising:

• a circuit substrate support;
• a plurality of electrically conductive pads attached to said support to which components are to be electrically connected
• a plurality of electrically conductive traces adhered to said support and beginning and ending on top of said pads to form electrical pathways between said pads, said traces being formed by extrusion of a polymer thick film from an orifice, some of said plurality of traces crossing over a countable number of other traces;
• said circuit board wherein said traces are coated with an electrically insulating material and formed by extrusion of said insulating material along said pathways.