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Laser method for forming vias

Imported: 25 Feb '17 | Published: 06 Aug '02

Chun-Chi Lee, Jaw-Shiun Hsieh, Yao-Hsin Feng, Shyh-Ing Wu, Kuan-Neng Liao, Chin-Pei Tien

USPTO - Utility Patents

Abstract

A laser method for forming vias comprises: providing a heat sink; locally oxidizing a surface of the heat sink into a copper oxide film; bonding a substrate onto the heat sink at the copper oxide layer locations, wherein the substrate comprises at least a patterned trace layer and an insulating layer to which is bonded the heat sink, the insulating layer comprising a plurality of through holes that expose the portions of the copper oxide film; removing the copper oxide exposed through the through holes by laser beam; disposing a plurality of solder balls respectively in the through holes; and reflowing the solder balls to form a plurality of vias.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,

FIG. 1 is a flow chart illustrating a conventional process for forming vias;

FIG.

2 through FIG. 5 are cross-sectional views schematically illustrating various stages in a conventional process for forming vias;

FIG. 6 is a flow chart showing various steps of a laser method for forming vias according to a first embodiment of the present invention;

FIG.

7 through FIG. 10 are cross-sectional views schematically illustrating various stages in the laser method for forming vias in accordance with the method illustrated by the flow chart of FIG. 6, according to the first embodiment of the present invention;

FIG. 11 is a flow chart showing various steps of a laser method for forming vias according to a second embodiment of the present invention; and

FIG.

12 through FIG. 15 are cross-sectional views schematically illustrating various stages in the laser method for forming vias in accordance with the flow chart of FIG. 11, according to the second embodiment of the present invention.

Claims

1. A laser method for forming vias that can be used for a cavity down packaging, comprising:

2. The laser method of claim 1, wherein the material of the insulating layer is selected from a group that consists of glass epoxy resins, bismaleimide-triazine (BT), epoxy resins, and polyimide.

3. The laser method of claim 1, wherein the patterned trace layer is formed by photolithography process applied to a copper foil.

4. The laser method of claim 1, wherein the material of the solder balls is tin-lead alloy.

5. The laser method of claim 1, wherein the material of the heat sink is copper.

6. The laser method of claim 1, wherein the heat sink comprises a chip-mounting region and a substrate-mounting region located at the periphery of the chip-mounting region.

7. The laser method of claim 1, wherein the substrate is bonded onto the oxide layer of the heat sink via an adhesive layer.

8. The laser method of claim 1, wherein the laser that is used is a carbon dioxide laser.

9. The laser method of claim 1, wherein the laser that is used is a yttrium-aluminum-garnet (YAG) laser.

10. A laser method for forming vias, comprising:

11. The laser method of claim 10, wherein the material of the first insulating layer is selected from a group that consists of glass epoxy resins, bismaleimide-triazine (BT), epoxy resins, and polyimide.

12. The laser method of claim 10, wherein the material of the second insulating is selected from a group that consists of glass epoxy resins, bismaleimide-triazine (BT), epoxy resins, and polyimide.

13. The laser method of claim 10, wherein the first and second patterned trace layers are formed by photolithography process applied to a copper foil.

14. The laser method of claim 10, wherein the material of the solder balls is tin-lead alloy.

15. The laser method of claim 10, wherein the laminate is bonded to the substrate via an adhesive layer.

16. The laser method of claim 10, wherein the laser that is used is a carbon dioxide laser.

17. The laser method of claim 10, wherein the laser that is used is a yttrium-aluminum-garnet (YAG) laser.