BASE MATERIAL AND METHOD FOR THE MANUFACTURE OF PRINTED CIRCUITS

• US 3,625,758 A
• Filed: 02/21/1967
• Issued: 12/07/1971
• Est. Priority Date: 02/22/1966
• Status: Expired due to Term

• Current Assignee: Frederick W. Schneble Jr, Fritz Theodor Stahl, Hedwij Maria Steffen, John F. Mccormack
• Original Assignee: Frederick W. Schneble Jr, Fritz Theodor Stahl, Hedwij Maria Steffen, John F. Mccormack
• Inventors: Stahl, Fritz Theodor, Steffen, Hedwij Maria, Schneble, Frederick W. Jr., McCormack, John F.
• Primary Examiner(s): Leavitt, Alfred L.
• Assistant Examiner(s): Grimaldi, Alan
• Application Number:
  US04/617,502
• Time in Patent Office: 1,750 Days
• Field of Search: 29/625 317/11A 174/68.5 117/212,217,47R
• US Class Current: 428/206
• CPC Class Codes: C23C 18/208 with use of metal first
• CPC Class Codes: C23C 18/2086 with use of organic or inorganic compounds other than metals, first
• CPC Class Codes: C23C 18/24 using acid aqueous solutions
• CPC Class Codes: C23C 18/30 Activating or accelerating or sensitising with palladium or other noble metal
• CPC Class Codes: C23C 18/405 Formaldehyde
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/0212 Resin particles
• CPC Class Codes: H05K 2203/0773 Dissolving the filler without dissolving the matrix material; Dissolving the matrix material without dissolving the filler
• CPC Class Codes: H05K 3/387 for electroless plating H05K3/4661 takes precedence
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 428/24893 including particulate material
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/249978 Voids specified as micro

Abstract

This invention relates to metallizing insulating base materials and more particularly to rendering insulating materials sensitive to electroless metal deposition and then depositing electroless metal on the sensitized material, and to the resulting new and improved metallized articles, including printed circuit boards.

Claims

2. The article of claim 1 wherein said microporous surface is catalytic to the reception of electroless metal.

3. The article of claim 2 wherein an electroless metal deposit is adhered to the catalytic, microporous surface of the resinous layer.

4. A printed circuit board comprising an insulating core, an insulating resinous layer adhered to the core and heat cured thereon, said layer having uniformly distributed therein finely divided particles consisting essentially of a member selected from the group consisting of oxidizable and degradable natural and synthetic rubber and mixtures thereof, and the eXposed surface of such layer having an electroless metal adhered thereto in a desired conductor pattern, such exposed layer having first been rendered microporous by degrading the finely divided rubber particles adjacent the exposed surface of said resinous layer with an oxidizing agent, sensitized and then contacted with an electroless metal deposition solution to achieve the desired conductor pattern.

5. The printed circuit board according to claim 4 wherein the desired conductor pattern consists of an electroless metal deposit and a galvanic metal deposit.

6. The printed circuit board of claim 4 wherein the desired conductor pattern included plated through holes.

7. The method of manufacturing printed circuit boards which comprises establishing an insulating base material comprising an insulating core and an insulating resinous layer adhered to the core and heat cured thereon, said resinous layer comprising finely divided particles consisting essentially of a member selected from the group consisting of oxidizable and degradable natural and synthetic rubber and mixtures thereof, masking selected portions of the surface to leave exposed areas corresponding to a desired pattern of conductors, degrading the finely divided rubber particles adjacent the surface of the resinous surface with an oxidizing chemical to render the exposed areas microporous, sensitizing the resulting microporous surface to the reception of electroless metal, and then contacting the resulting surface with an electroless metal deposition solution to form a deposit of electroless metal of a desired thickness on the exposed areas to form the desired pattern of conductors.

8. The method of claim 7 wherein holes are provided in the base, and the walls surrounding the holes are provided with the insulating resinous layer in which the finely divided rubber particles adjacent the surface have been degraded with an oxidizing chemical to render it microporous, including the steps of sensitizing the microporous areas and contacting the base with an electroless metal deposition solution to form a desired conductor pattern with plated through holes.

9. In a process for metallizing an insulating base material which comprises contacting a sensitizing base material with an electroless metal deposition solution the improvement which comprises establishing an insulating base material comprising an insulating core and an insulating resinous layer adhered to the core and heat cured thereon, said resinous layer comprising finely divided particles consisting essentially of a member selected from the group consisting of oxidizable and degradable natural and synthetic rubber and mixtures thereof, degrading the finely divided rubber particles adjacent the surface of the resinous layer with an oxidizing agent to render it microporous, sensitizing the resulting microporous surface to the reception of electroless metal, and then contacting the sensitized microporous surface with an electroless metal deposition solution to adherently deposit electroless metal thereon.

10. The method of claim 9 wherein the oxidizing agent is a mixture of chromic acid and sulfuric acid.

11. The method of claim 10 wherein electroless metal deposition is continued until the deposit has a thickness of between about 0.5 and 5 microns.

12. The method of claim 9 wherein the sensitized microporous surface is contacted with an electroless metal deposition solution followed by a galvanic deposition of said metal.

13. The method of manufacturing printed circuit boards which comprises establishing an insulating base material comprising an insulating core and an insulating resinous layer adhered to the core and heat cured thereon, said resinous layer comprising finely divided particles consisting essentially of a member selected from the group consisting of oxidizable and degradable natural and synthetic rubber and mixtures thereof, degrading the finely divided rubber particles adjacent the surface of the resinous surface with an oxidizing chemical to render the exposed areas microporous, printing the insulating resinous layer following treatment with the oxidizing chemical with a mask which leaves free regions corresponding to the desired circuit pattern sensitizing the said free regions to the deposition of electroless metal, removing the mask and subjecting the resulting article to an electroless deposition solution to deposit metal on the sensitized areas.

14. The method of claim 13 wherein holes are provided in the base and the walls surrounding the holes are provided with the insulating resinous layer in which the finely divided rubber particles adjacent the surface have been degraded with an oxidizing chemical to render it microporous, including the steps of sensitizing the microporous areas and contacting the base with an electroless metal deposition solution to form a desired conductor pattern with plated through holes.