Multilayer circuit board having at least one core substrate arranged therein

• US 6,222,740 B1
• Filed: 12/11/1998
• Issued: 04/24/2001
• Est. Priority Date: 12/19/1997
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Ulmer, Helmut, Messarosch, Gerhard, Bovensiepen, Kurt
• Primary Examiner(s): Sough, Hyung-Sub
• Assistant Examiner(s): Vigushin, John B.
• Application Number:
  US09/209,714
• Time in Patent Office: 865 Days
• Field of Search: 361/719-721, 361/748-751, 361/792-795, 428/209, 428/210, 428/212, 428/213, 428/217, 428/218, 428/220, 428/901, 174/255, 174/260, 174/256, 298/30, 298/46
• US Class Current: 361/795
• CPC Class Codes: H05K 1/0271 Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion
• CPC Class Codes: H05K 1/056 the metal substrate being covered by an organic insulating layer
• CPC Class Codes: H05K 2201/0323 Carbon
• CPC Class Codes: H05K 2201/068 wherein the coefficient of thermal expansion is important
• CPC Class Codes: H05K 2201/10416 Metallic blocks or heatsinks completely inserted in a PCB metallic supports H05K3/0061
• CPC Class Codes: H05K 2201/10727 Leadless chip carrier [LCC], e.g. chip-modules for cards
• CPC Class Codes: H05K 3/3442 having edge contacts, e.g. leadless chip capacitors, chip carriers
• CPC Class Codes: H05K 3/4641 having integrally laminated metal sheets or special power cores
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A multilayer circuit board includes multiple conductor path planes arranged one above another and separated by insulating material layers. The multilayer circuit board includes at least one electronic component (in particular an LCCC) placed on one of the two outer sides of the multilayer circuit board. The multilayer circuit board includes at least one core substrate arranged in the multilayer circuit board between the outer insulating material layers. The core substrate largely adapts the thermal expansion properties of the multilayer circuit board, at least in the coverage area of the electronic component, to the thermal expansion properties of the component. In order to achieve a reduction in the weight of the multilayer circuit board, an inner layer portion, equipped with a recess, is provided between the two outer insulating material layers. The lateral extent of the recess in the inner layer portion is confined approximately to the coverage area of the electronic component, and the core substrate is introduced into the recess. Advantageously, the inner layer portion can also receive multiple conductor path planes separated by insulating material layers, thus achieving a further reduction in the size of the circuit board.

Claims

1. A multilayer circuit board having a first outer side and a second outer side, comprising:

a plurality of insulating material layers including at least a first outer insulating material layer and a second outer insulating material layer;

a plurality of conductor path planes extending in a direction parallel to the plurality of insulating material layers and arranged one above another and being separated from each other by the plurality of insulating material layers;

at least one electronic component situated on one of the first outer side and the second outer side;

at least one core substrate arranged between the first outer insulating material layer and the second outer insulating material layer, the at least one core substrate adapting a plurality of thermal expansion properties of the multilayer circuit board, at least in a coverage area of the at least one electronic component, to a plurality of thermal expansion properties of the at least one electronic component; and

an inner layer portion having a recess, the inner layer portion being situated between the first outer insulating material layer and the second outer insulating material layer, and including printed circuit traces which extend in a direction parallel to the first outer insulating material layer and the second outer insulating material layer, the recess having a lateral extent confined substantially to the coverage area of the at least one electronic component, wherein the at least one core substrate is arranged within the recess.

2. The multilayer circuit board according to claim 1, wherein the at least one electronic component includes an LCCC component.

3. The multilayer circuit board according to claim 1, wherein the at least one core substrate is arranged in the recess in a tight-fitting manner.

4. The multilayer circuit board according to claim 1, wherein the inner layer portion is arranged according to a centered orientation between the first outer insulating material layer and the second outer insulating material layer.

5. The multilayer circuit board according to claim 1, wherein the at least one core substrate includes a molybdenum core.

6. The multilayer circuit board according to claim 1, wherein the at least one core substrate includes a carbon fiber core containing a plurality of unidirectional carbon fiber plies arranged one above another.

7. The multilayer circuit board according to claim 1, further comprising a metal coating applied at least onto each outer side of the at least one core substrate facing a corresponding one of the plurality of insulating material layers.

8. The multilayer circuit board according to claim 7, wherein the metal coating includes copper.

9. The multilayer circuit board according to claim 7, wherein the metal coating includes a black-oxidized copper coating.

10. A multilayer circuit board having a first outer side and a second outer side, comprising:

a plurality of insulating material layers including at least a first outer insulating material layer and a second outer insulating material layer;

a plurality of conductor path planes arranged one above another and being separated from each other by the plurality of insulating material layers;

at least one electronic component situated on one of the first outer side and the second outer side;

at least one core substrate arranged between the first outer insulating material layer and the second outer insulating material layer, the at least one core substrate adapting a plurality of thermal expansion properties of the multilayer circuit board, at least in a coverage area of the at least one electronic component, to a plurality of thermal expansion properties of the at least one electronic component; and

an inner layer portion having a recess, being situated between the first outer insulating material layer and the second outer insulating material layer, and including printed circuit traces, the recess having a lateral extent confined substantially to the coverage area of the at least one electronic component, wherein the at least one core substrate is arranged within the recess;

wherein the inner layer portion includes a second plurality of conductor path planes and a second plurality of insulating material layers for separating the second plurality of conductor path planes from each other.

11. A multilayer circuit board having a first outer side and a second outer side, comprising:

a plurality of insulating material layers including at least a first outer insulating material layer and a second outer insulating material layer;

a plurality of conductor path planes extending in a direction parallel to the plurality of insulating material layers and arranged one above another and being separated from each other by the plurality of insulating material layers;

at least one electronic component situated on one of the first outer side and the second outer side;

at least one core substrate arranged between the first outer insulating material layer and the second outer insulating material layer, the at least one core substrate adapting a plurality of thermal expansion properties of the multilayer circuit board, at least in a coverage area of the at least one electronic component, to a plurality of thermal expansion properties of the at least one electronic component; and

an inner layer portion having a recess, the inner layer portion being situated between the first outer insulating material layer and the second outer insulating material layer, and including printed circuit traces which extend in a direction parallel to the first outer insulating material layer and the second outer insulating material layer, the recess having a lateral extent confined substantially to the coverage area of the at least one electronic component, wherein the at least one core substrate is arranged within the recess;

wherein the at least one core substrate includes a carbon fiber core containing a plurality of unidirectional carbon fiber plies arranged one above another; and

wherein the carbon fiber core includes four unidirectional carbon fiber plies of identical thickness, wherein the four unidirectional carbon fiber plies include two center carbon fiber plies and two outer carbon fiber plies, and wherein the two center carbon fiber plies include carbon fibers that are parallel to each other and are displaced according to a 90-degree offset from carbon fibers of the two outer carbon fiber plies.