Printed circuit board

• US 7,459,202 B2
• Filed: 07/03/2006
• Issued: 12/02/2008
• Est. Priority Date: 07/03/2006
• Status: Expired due to Fees

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Dunn, Gregory J., Magera, Jaroslaw A.
• Primary Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US11/428,454
• Publication Number:
  US 20080003414A1
• Time in Patent Office: 883 Days
• Field of Search: 174260-266, 174250-255, 361792-795, 428/209
• US Class Current: 428/209
• CPC Class Codes: H05K 1/116 Lands, clearance holes or other lay-out details concerning the surrounding of a via
• CPC Class Codes: H05K 2201/09063 Holes or slots in insulating substrate not used for electrical connections
• CPC Class Codes: H05K 2201/09918 Optically detected marks used for aligning tool relative to the PCB, e.g. for mounting of components
• CPC Class Codes: H05K 2203/1438 Treating holes after another process, e.g. coating holes after coating the substrate metal used as mask for etching vias H05K2203/0554
• CPC Class Codes: H05K 3/0008 for aligning or positioning of tools relative to the circuit board H05K3/4638, H05K3/4679 take precedence; for manufacturing assemblages of components H05K13/0015
• CPC Class Codes: H05K 3/0047 Drilling of holes
• CPC Class Codes: H05K 3/025 by transfer of thin metal foil formed on a temporary carrier, e.g. peel-apart copper
• CPC Class Codes: H05K 3/205 using a pattern electroplated or electroformed on a metallic carrier
• CPC Class Codes: H05K 3/427 initial plating of through-holes in metal-clad substrates
• CPC Class Codes: H05K 3/428 initial plating of through-holes in substrates having a metal pattern
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

A sequentially laminated printed circuit board having highly reliable vias can be fabricated by pattern plating flanges or via lands on a copper foil, laminating the foil to a prepreg so that the flanges are embedded into the surface of the prepreg, creating via holes in the laminate that are substantially concentric with the individual flanges, plating the via holes with copper, chemically or mechanically milling off a portion of the copper plating and optionally some of the copper foil to reduce the overall thickness of the laminate, and laminating a second and optionally a third prepreg to the laminate. The resulting printed circuit board has the flanges embedded in the surface of the laminate so that the inside wall of the flange is electrically and mechanically attached to the outside wall of the plated through hole barrel.

Claims

1. A printed circuit board, comprising:

a deformed thermoset dielectric medium, comprising a polymer, having a major surface;

one or more apertures formed in the deformed thermoset dielectric medium, each aperture having a layer of copper deposited on aperture walls thereof;

a copper flange embedded into the major surface of the deformed thermoset dielectric medium and substantially concentric to a central axis of the aperture, wherein interior vertical walls of the flange are attached to an outer portion of the layer of copper on the aperture wall,wherein the thickness of the copper flange is equal to or greater than two times the thickness of the layer of copper on the aperture walls; and

a copper foil situated on at least portions of the major surface of the deformed thermoset dielectric medium, with portions of the copper foil overlying the copper flange.

2. The printed circuit board as described in claim 1, wherein the deformed thermoset dielectric medium further comprises glass fiber reinforcement in the polymer.

3. The printed circuit board as described in claim 1, further comprising an additional layer of dielectric medium on a surface of the deformed thermoset dielectric medium opposite the major surface.

4. The printed circuit board as described in claim 3, wherein the aperture is filled with portions of the additional layer of dielectric medium.

5. The printed circuit board as described in claim 4, further comprising an additional copper plating situated on the filled portion of the aperture, and on the copper foil.

6. The printed circuit board as described in claim 1, wherein the copper foil situated on at least portions of the major surface of the deformed thermoset dielectric medium comprises circuit conductors.

7. The printed circuit board as described in claim 1, wherein the copper flanges are shaped as diamond, triangular, square, rectangular, pentagonal, hexagonal, octagonal, round, elliptical, or polygonal.

8. The printed circuit board as described in claim 1, wherein the thickness of the copper flange is greater than 1.0 mil and greater than the thickness of the layer of copper on the aperture walls.

9. A printed circuit board, comprising:

a glass-reinforced thermoset polymer substrate, having a major surface;

one or more apertures formed in the glass-reinforced thermoset polymer substrate, each aperture having a layer of copper deposited on aperture walls thereof, and filled with the polymer;

a copper flange embedded into the major surface of the glass-reinforced thermoset polymer substrate and substantially concentric to a central axis of the aperture, wherein interior vertical walls of the flange are attached to an outer portion of the layer of copper on the aperture wall, and wherein the thickness of the copper flange is greater than 1.0 mil and equal to of greater than 1.5 times the thickness of the layer of copper on the aperture wall; and

a copper foil situated on at least portions of the major surface of the glass-reinforced thermoset polymer substrate, with portions of the copper foil overlying the copper flange.

10. The printed circuit board as described in claim 9, wherein the copper foil situated on at least portions of the major surface of the glass-reinforced thermoset polymer substrate comprises circuit conductors.

11. The printed circuit board as described in claim 9, further comprising an additional layer of a glass-reinforced thermoset polymer substrate on a surface of the glass-reinforced thermoset polymer substrate opposite the major surface.

12. The printed circuit board as described in claim 9, wherein the shape of the copper flanges is selected from the group consisting of diamond, triangular, square, rectangular, pentagonal, hexagonal, octagonal, round, elliptical, and polygonal.

13. The printed circuit board as described in claim 9, further comprising an additional copper plating situated on the filled portion of the aperture, and on the copper foil.

14. A printed circuit board, comprising:

a first glass-reinforced thermoset polymer substrate having a plurality of plated-through-holes therein, at least some of the plated-through-holes having a copper collar situated around an upper periphery thereof and embedded in the surface of the substrate such that an interior wall of the collar is attached to an exterior wall of a barrel of the plated-through-hole, and such that the thickness of the copper collar is greater than 1.0 mil and equal to or greater than 1.5 times the the thickness of the barrel;

a copper foil attached to a non-embedded portion of the collar and to portions of the surface of the first glass-reinforced thermoset polymer substrate; and

a second glass-reinforced thermoset polymer substrate laminated to an opposing surface of the first glass-reinforced thermoset polymer substrate, portions of the second glass-reinforced thermoset polymer substrate filling the at least some of the plated-through-holes.

15. The printed circuit board as described in claim 14, wherein the copper foil comprises circuit conductors.

16. The printed circuit board as described in claim 14, wherein the shape of the copper flanges is selected from the group consisting of diamond, triangular, square, rectangular, pentagonal, hexagonal, octagonal, round, elliptical, and polygonal.

17. The printed circuit board as described in claim 14, further comprising an additional copper plating situated on the filled portion of the plated-through-hole, and on the copper foil.