Printed circuit board capacitor structure and method

• US 6,215,649 B1
• Filed: 11/05/1998
• Issued: 04/10/2001
• Est. Priority Date: 11/05/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lauffer, John M., Appelt, Bernd K.
• Primary Examiner(s): Kincaid, Kristine
• Assistant Examiner(s): THOMAS, ERIC W
• Application Number:
  US09/186,583
• Time in Patent Office: 887 Days
• Field of Search: 361/301.1, 361/301.2, 361/301.4, 361/301.5, 361/311, 361/312, 361/306.3, 361/323, 361/324, 361/321, 361/321--32, 361/761, 361/762, 361/763
• US Class Current: 361/312
• CPC Class Codes: H05K 1/0366 reinforced, e.g. by fibres, fabrics H05K1/036 takes precedence
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0195 Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/09309 Core having two or more power planes; Capacitive laminate of two power planes
• CPC Class Codes: H05K 3/429 Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers
• CPC Class Codes: H05K 3/4641 having integrally laminated metal sheets or special power cores
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49144 by metal fusion
• CPC Class Codes: Y10T 29/5102 Binding or covering and cutting

Abstract

A capacitive element for a circuit board or chip carrier having improved capacitance and method of manufacturing the same is provided. The structure is formed from a pair of conductive sheets having a dielectric component laminated therebetween. The dielectric component is formed of two or more dielectric sheets at least one of which can be partially cured or softened followed by being fully cured or hardened. The lamination takes place by laminating a partially cured or softened sheet to at least one other sheet of dielectric material and one of the sheets of conductive material. The total thickness of the two sheets of the dielectric component does not exceed about 4 mils and preferably does not exceed about 3 mils; thus the single dielectric sheets does not exceed about 2 mils and preferably does not exceed about 1.5 mils in thickness. The use of two or more sheets of dielectric material makes it very unlikely that two or more defects in the sheets of dielectric material will align thus greatly reducing the probability of a defect causing a failure in test or field use.

Claims

1. A capacitive element, comprising:

at least two sheets of thermoplastic or thermosetting resinous dielectric material, each sheet containing at least one resin impregnated sheet of glass cloth and having a thickness of between about 1 mil and about 2 mils, said sheets of dielectric material being bonded together to form a dielectric component having a thickness of between about 2 mils and about 4 mils;

first and second sheets of conductive material;

said dielectric component being laminated between said first and second sheets of conductive material and being fully cured or hardened.

2. The capacitive element according to claim 1 wherein three sheets of dielectric material are bonded together to form the dielectric component.

3. The capacitive element according to claim 1 wherein the at least two sheets are formed from different materials.

4. The invention as defined in claim 1 wherein the sheets of cloth incorporate an epoxy resin which is fully cured.