Craig L Wilson

US Patent:

6645549, Nov 11, 2003

Filed:

Oct 11, 2001

Appl. No.:

09/958647

Inventors:

Darryl J. McKenney - Londonderry NH
Arthur J. Demaso - Nashua NH
Kathy A. Gosselin - Atkinson NH
Craig S. Wilson - Brookline NH

Assignee:

Parlex Corporation - Methuen MA

International Classification:

C25D 360

US Classification:

427 98, 427435, 427409, 427410, 427386, 205 87, 205252, 205191, 205300

Abstract:

A process for providing bond enhancement and an etch resist for a printed circuit board is provided. A sheet comprising at least a layer of copper is immerses in a first immersion tin solution comprising a tin metal and a complexing agent in an acidic medium for a time sufficient to deposit a first heavy tin deposit on the sheet. The sheet is then immersed in a second immersion tin solution comprising stannous tin ions and stannic tin ions and a complexing agent in an acidic medium for a time sufficient to deposit a second thin tin deposit on the sheet. The second thin tin deposit has a thickness less than a thickness of the first heavy tin deposit. A rough surface texture providing mechanical adhesion sites results. The board is then treated with a coupling agent, such as silane, for enhanced bonding to a subsequent epoxy or other polymer prepreg. Additionally, the first heavy tin deposit may serve as an etch resist in subsequent fabrication of the provided circuit board.

US Patent:

60997451, Aug 8, 2000

Filed:

May 4, 1999

Appl. No.:

9/304916

Inventors:

Darryl McKenney - Londonderry NH
Arthur Demaso - Nashua NH
Craig Wilson - Brookline NH

Assignee:

Parlex Corporation - Methuen MA

International Classification:

H05K 100
H05K 306

US Classification:

216 13

Abstract:

In a rigid/flex circuit board and fabricating process, patterns of electrical traces are formed by etching conductive layers on outer surfaces of a flexible multi-layer circuit structure. A protective barrier material is deposited on the etched traces using an "electroless" process, such as immersion of the flexible circuit board in an aqueous solution containing ionic tin. The protective barrier material adheres to and encapsulates the copper traces. An outer circuit structure including a bondfilm of epoxy-impregnated fiberglass ("prepreg" bondfilm) and a copper foil layer is laminated onto the flexible circuit structure. The prepreg bondfilm has a window area removed by routing or an equivalent process prior to being laminated to the flexible structure. The window area defines a flex area of the rigid/flex circuit board that will be relatively flexible. The portion of the outer copper foil above the window area of the prepreg bondfilm is then removed using a chemical etchant to which the previously-applied protective barrier material is immune, such as an ammoniacal etching solution.