MLC conductor pattern off-set design to eliminate line to via cracking

• US 5,446,246 A
• Filed: 01/24/1994
• Issued: 08/29/1995
• Est. Priority Date: 07/29/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Desai, Kamalesh S., DiAngelo, Donald W.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Figlin, Cheryl R.
• Application Number:
  US08/186,227
• Time in Patent Office: 582 Days
• Field of Search: 174/51, 174/52.2, 174/52.3, 174/262, 174/263, 174/264, 174/265, 174/266
• US Class Current: 174/262
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 1/113 Via provided in pad; Pad over filled via
• CPC Class Codes: H05K 3/4053 by thick-film techniques

Abstract

A semiconductor ceramic packaging substrate has the usual vias of sintered electrically conductive metal extending through the substrate. There are the usual metal conductor lines comprising conductive elements on the surface of the substrate. Each via is connected to the conductive elements in a predetermined pattern through a conductive via cap on the surface of the ceramic package. The caps join each conductive element and each via. The cap has a width substantially larger than the diameter of the via at the point of contact of the via and the conductive element in contact with it. The caps are also substantially thicker and wider than the conductive elements.

Claims

1. A process to eliminate line to via cracking comprising the steps of,

(a) forming a solid via inside a substrate such that one end of said via is exposed and substantially shares the surface of said substrate,

(b) forming a via cap over said exposed via such that said exposed via is completely enveloped by said via cap and wherein said via cap is substantially larger in size than said via, and

(c) forming a line to electrically connect said via through said via cap.

2. The process of claim 1, wherein said substrate is a ceramic substrate.

3. The process of claim 1, wherein said substrate is a glass ceramic substrate.

4. The process of claim 1, wherein said via has a first diameter and said via cap has a second diameter at the point of contact with said via and wherein said second diameter is about 1.5 to about 2.0 times larger than said first diameter.

5. The process of claim 1, wherein said via cap has a width substantially larger than the diameter of said via at the point of contact between said via cap and said via.

6. The process of claim 1, wherein said via cap has a substantially round shape at one end which is over said via and a substantially square shape at the opposite end.

7. The process of claim 1, wherein said via has a diameter between about 75 microns to about 175 microns and said via cap has a diameter of between about 125 microns to about 225 microns.

8. The process of claim 7, wherein the width of said line is between about 75 microns to about 125 microns.

9. The process of claim 7, wherein said via cap has a thickness from about 25 microns to about 50 microns.

10. The process of claim 1, wherein steps (b) and (c) are performed simultaneously.

11. A structure to eliminate line to via cracking comprising, a solid via embedded in a substrate such that at least one end of said via is exposed and is substantially parallel to the surface of said substrate, a via cap which is substantially larger than said via completely envelopes said via, and an electrically conductive line provides electrical connection to said via through said via cap.

12. The structure of claim 11, wherein said substrate is a ceramic substrate.

13. The structure of claim 11, wherein said substrate is a glass ceramic substrate.

14. The structure of claim 11 wherein said via has a first diameter and said via cap has a second diameter at the point of contact with said via and wherein said second diameter is about 1.5 to about 2.0 times larger than said first diameter.

15. The structure of claim 11, wherein said via cap has a width substantially larger than the diameter of said via at the point of contact between said via cap and said via.

16. The structure of claim 11, wherein said via cap has a substantially round shape at one end which is over said via and a substantially square shape at the opposite end.

17. The structure of claim 11, wherein said via has a diameter between about 75 microns to about 175 microns and said via cap has a diameter of between about 125 microns to about 225 microns.

18. The structure of claim 17, wherein the width of said line is between about 75 microns to about 125 microns.

19. The structure of claim 17, wherein said via cap has a thickness from about 25 microns to about 50 microns.