Copper clad epoxy printed circuit board suitable for microwave frequencies encountered in GPS receivers

• US 5,268,064 A
• Filed: 02/04/1992
• Issued: 12/07/1993
• Est. Priority Date: 02/04/1992
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Woo, Arthur N., Tom, Paul K.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/830,733
• Time in Patent Office: 672 Days
• Field of Search: 156/630, 156/634, 156/651, 156/656, 156/659.1, 156/661.1, 156/666, 156/902, 174/255, 174/256, 174/258, 174/259, 428/209, 428/901, 134/26, 134/28, 29/846
• US Class Current: 216/20
• CPC Class Codes: H05K 1/0242 Structural details of individual signal conductors, e.g. related to the skin effect
• CPC Class Codes: H05K 1/0326 containing O
• CPC Class Codes: H05K 2201/0715 provided by an outer layer of PCB
• CPC Class Codes: H05K 2203/0392 Pretreatment of metal, e.g. before finish plating, etching improvement of the adhesion between an insulating substrate and a metal by special treatment of the metal H05K3/382
• CPC Class Codes: H05K 3/384 by plating
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4652 Adding a circuit layer by laminating a metal foil or a preformed metal foil pattern H05K3/4647 takes precedence

Abstract

A method for making printed circuit boards comprises using double treated copper foils for all inside conductor layers of multilayer packages with substrates of alloys of epoxy and polyphenylene oxide (PPO) resin to counteract the skin-effect encountered at high frequencies. Direct bonds between inside surfaces are then used without using an oxide step that introduces red/brown or black oxides.

Claims

1. A method for fabricating a multilayer printed circuit board (PCB) package, the method comprising the steps of:

bonding double-treated copper foil to a substrate of an alloy of epoxy and polyphenylene oxide (PPO) resin to form a first laminate;

etching a circuit pattern in said double-treated copper foil; and

direct bonding under heat and pressure the double-treated copper foil side of said first laminate to a second laminate comprised of an alloy of epoxy and polyphenylene oxide (PPO) resin.

2. The method of claim 1 wherein:

the step of direct bonding comprises stripping developed dry film to create traces mimicking film patterns and then proceeding directly to drying said first laminate to remove excess moisture.

3. The method of claim 1, further comprising the step of:

precleaning said first laminate before the step of etching.

4. The method of claim 3, wherein the step of precleaning comprises the constituent steps of:

baking said first laminate in an air-circulating oven for approximately four hours at 325°

F.;

dipping said first laminate in a preplating cleaner;

rinsing said first laminate in water;

dipping the laminates in a microetch solution;

rinsing said first laminate in water;

dipping said first laminate in a copper conditioning bath;

rinsing said first laminate in water; and

drying said first laminate in an air dryer.