GB2137422A - Printed circuit board - Google Patents

Printed circuit board Download PDF

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Publication number
GB2137422A
GB2137422A GB08308882A GB8308882A GB2137422A GB 2137422 A GB2137422 A GB 2137422A GB 08308882 A GB08308882 A GB 08308882A GB 8308882 A GB8308882 A GB 8308882A GB 2137422 A GB2137422 A GB 2137422A
Authority
GB
United Kingdom
Prior art keywords
printed circuit
cores
circuit board
metal
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08308882A
Other versions
GB8308882D0 (en
GB2137422B (en
Inventor
Geoffrey Charles Wilson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ferranti International PLC
Original Assignee
Ferranti PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ferranti PLC filed Critical Ferranti PLC
Priority to GB08308882A priority Critical patent/GB2137422B/en
Publication of GB8308882D0 publication Critical patent/GB8308882D0/en
Publication of GB2137422A publication Critical patent/GB2137422A/en
Application granted granted Critical
Publication of GB2137422B publication Critical patent/GB2137422B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4611—Manufacturing multilayer circuits by laminating two or more circuit boards
    • H05K3/4641—Manufacturing multilayer circuits by laminating two or more circuit boards having integrally laminated metal sheets or special power cores
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H05K1/0203—Cooling of mounted components
    • H05K1/0207—Cooling of mounted components using internal conductor planes parallel to the surface for thermal conduction, e.g. power planes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
    • H05K1/0203—Cooling of mounted components
    • H05K1/0204—Cooling of mounted components using means for thermal conduction connection in the thickness direction of the substrate
    • H05K1/0206—Cooling of mounted components using means for thermal conduction connection in the thickness direction of the substrate by printed thermal vias
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09209—Shape and layout details of conductors
    • H05K2201/095—Conductive through-holes or vias
    • H05K2201/09536—Buried plated through-holes, i.e. plated through-holes formed in a core before lamination
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
    • H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
    • H05K2201/10621—Components characterised by their electrical contacts
    • H05K2201/10727—Leadless chip carrier [LCC], e.g. chip-modules for cards
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H05K3/429—Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4611—Manufacturing multilayer circuits by laminating two or more circuit boards
    • H05K3/4623—Manufacturing multilayer circuits by laminating two or more circuit boards the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards

Abstract

A printed circuit board includes two metal cores 10 and 11 arranged parallel to one another and separated by one or more intermediate printed circuit layers 12. These layers are insulated from one another and from the metal cores. A separate printed circuit layer 14 is secured to the outer surface of at least one of the metal cores, and is arranged to carry circuit components. Plated-through holes 17 interconnect the various printed circuit layers. Heat-conducting members may be provided to interconnect the two metal cores, and either or both of the cores may be arranged to be attached to a cold sink. <IMAGE>

Description

SPECIFICATION Printed circuit boards This invention relates to printed circuit boards, and particularly to such boards having a metal core. A printed circuit board in its simplest form consists of an insulating substrate carrying on at least one surface a pattern of metallic conductors. If both sides of the board are used, then plated-through holes are used to interconnect parts of the pattern on opposite sides of the board. Multi-layer printed circuit boards consist of several layers of interconnecting conductors insulated from one another. In all cases, the necessary circuit components are carried on the external surfaces of the board, usually attached to the conduction pattern by soldered connections.
One of the problems associated with printed circuits is that of removing heat generated by the circuit components. When discrete components were used it was usually possible to remove heat by natural convection, or if necessary by blowing air over or between the boards. However, the advent of the integrated circuit increased the component packing density and hence the number of possible heat sources on a single board. It is known for a printed circuit board to have a metal conducting pattern attached to one surface which was arranged to be in physical and thermal contact with the integrated circuit packages to remove heat from the packages.
However, since the integrated circuit packages themselves could be formed from a plastics material, the heat had first to be conducted through the package.
Additionally, the presence of the metal pattern on one surface of the board meant that conductor patterns either had to be removed from that surface or well insulated.
A more recent development has been to form the printed circuit on a metal core, with single or multi-layer conductor patterns formed in the usual way on one or both surfaces of the core. Platedthrough holes between conductor patterns on opposite sides of the core pass through holes in the core.
The metal core usually extends beyond the printed circuits along at least one edge to enable the core to be attached to a heat sink.
The main problem associated with the use of such boards is that distortion of the board may occur, particularly, when soldering of components to the printed circuit board is carried out. Even if this distortion is only temporary it can cause damage to the printed conductors or to the insulating layer to which they are secured, or similarly affect the soldered joints. In some cases the metal core is a sandwich of different metals, and differential thermal expansion may cause similar problems.
It is an object of the invention to provide a printed circuit board in which the above problem is avoided.
According to the present invention there is provided a printed circuit board which includes first and second metal cores arranged parallel to one another, at least one intermediate printed circuit layer separating and insulated from said cores, and a separate printed circuit layer secured to and insulated from the outer surface of at least one of said cores and arranged to carry circuit components, interconnections between any of said printed circuit layers being by means of plated-through holes.
Also according to the invention the first and second metal cores may be thermally connected to one another by means of heat-conducting members secured to each core and passing through the or each intermediate printed circuit layer.
The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a sectional side view of a printed circuit board according to a first embodiment of the invention; and Figure 2 shows a sectional view of a board according to a second embodiment, to a larger scale.
Referring now to Figure 1, this shows a section through a multi-layer printed circuit board having two metal cores 10 and 11. The two cores are separated by a number of printed circuit layers 12, insulated from one another and from the metal cores 10 and 11 by means of an electrically-insulating 13 frequently of an epoxy or polyimide glass fibre material. The outer surface of each of the metal cores supports a printed circuit layer 14, insulated from the core by an insulating layer 15. This outer layer 14 is arranged to carry circuit components, such as chip carriers 16, which are soldered to the printed circuit layer.
The various printed circuit layers are interconnected by plated-through holes 17, if necessary passing, through and insulated from the metal cores.
As shown in Figure 1, certain of the components mounted on the outer printed circuit layer 14 may be arranged to be in good thermal contact with the adjacent metal core 10, so as to remove heat from the component. Such an arrangement forms the subject-matter of our copending application No.
8304280.
Either or both of the metal may be extended to allow for its attachment to a cold sink so as to remove heat generated by the circuit components. In addition, the two metal cores ensure the stability of the board under thermal stress, and overcome a problem arising from the use of a single metal core.
Only one of the metal cores may be provided with an outer printed circuit layer 14,though in such a case the core only provides mechanical stability and has little effect on heat transfer since no heatgenerating components are carried by or close to it.
Figure 2 shows how the core which does not have an outer printed circuit layer may also help to cool the assembly. In this case a number of metal members 20 are provided to interconnect the two metal cores. The metal members require to have good thermal conductivity and to make good thermal contact with each metal core, and the heatgenerating component. Preferably the metal members are attached to the core adjacent to the position of a heat-generating component, so as to conduct the heat away more efficiently. If one core does not support an outer printed circuit layer then the whole outer surface of the core may be attached to a cold sink.
The metal members may be attached to the cores in any convenient way, such as soldering or riveting, as long as good thermal contact is ensured.
Each of the metal cores 10 and 11 may be in the form of a sheet of copper, or may be a copper/ nickel-ironlcopper sandwich. Other metals may also be suitable, either alone or in combination.

Claims (4)

1. A printed circuit board which includes first and second metal cores arranged parallel to one another, at least one intermediate printed circuit layer separating and insulated from said cores, and a separate printed circuit layer secured to and insulated from the outer surface of at least one of said cores and arranged to carry circuit components, interconnections between any of said printed circuit layers being by means of plated-through holes.
2. A printed circuit board as claimed in Claim 1 in which the first and second metal cores are thermally connected to one another by means of heatconducting members secured to each core and passing through the or each intermediate printed circuit layer.
3. A printed circuit board as claimed in either Claim 1 or 2 in which the outer face of each core carries a component-carrying printed circuit layer.
4. A printed circuit board substantially as herein described with reference to the accompanying draw ings.
GB08308882A 1983-03-30 1983-03-30 Printed circuit board Expired GB2137422B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08308882A GB2137422B (en) 1983-03-30 1983-03-30 Printed circuit board

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08308882A GB2137422B (en) 1983-03-30 1983-03-30 Printed circuit board

Publications (3)

Publication Number Publication Date
GB8308882D0 GB8308882D0 (en) 1983-05-11
GB2137422A true GB2137422A (en) 1984-10-03
GB2137422B GB2137422B (en) 1986-10-29

Family

ID=10540523

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08308882A Expired GB2137422B (en) 1983-03-30 1983-03-30 Printed circuit board

Country Status (1)

Country Link
GB (1) GB2137422B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0207012A2 (en) * 1985-06-17 1986-12-30 MAS INDUSTRIALE S.p.A. Method to ensure the cooling of electronic components fixed on a multilayer for printed circuits and multilayer realized according to said method
EP0399161A2 (en) * 1989-04-17 1990-11-28 International Business Machines Corporation Multi-level circuit card structure
GB2247782A (en) * 1990-09-05 1992-03-11 Marconi Gec Ltd A circuit board assembly
EP0603623A2 (en) * 1992-12-23 1994-06-29 International Business Machines Corporation Joining of layers and multi-layer circuit boards
GB2296604A (en) * 1994-12-24 1996-07-03 Bosch Gmbh Robert Electric device
EP0741504A3 (en) * 1995-05-05 1996-11-13 Bosch Gmbh Robert
GB2317503A (en) * 1996-09-20 1998-03-25 Motorola Inc Heat transfer apparatus suitable for use in a circuit board assembly
EP1781072A3 (en) * 2005-10-26 2007-05-16 Pentair Water Pool and Spa, Inc. Led pool and spa light

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1197281A (en) * 1966-10-17 1970-07-01 Ass Elect Ind Improvements in Thin Film Circuits
GB1594834A (en) * 1978-05-08 1981-08-05 Plessey Co Ltd Method of bonding a heat sink to a printed circuit board

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1197281A (en) * 1966-10-17 1970-07-01 Ass Elect Ind Improvements in Thin Film Circuits
GB1594834A (en) * 1978-05-08 1981-08-05 Plessey Co Ltd Method of bonding a heat sink to a printed circuit board

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0207012A2 (en) * 1985-06-17 1986-12-30 MAS INDUSTRIALE S.p.A. Method to ensure the cooling of electronic components fixed on a multilayer for printed circuits and multilayer realized according to said method
EP0207012A3 (en) * 1985-06-17 1989-03-15 MAS INDUSTRIALE S.p.A. Method to ensure the cooling of electronic components fixed on a multilayer for printed circuits and multilayer realized according to said method
EP0399161A2 (en) * 1989-04-17 1990-11-28 International Business Machines Corporation Multi-level circuit card structure
EP0399161A3 (en) * 1989-04-17 1991-01-16 International Business Machines Corporation Multi-level circuit card structure
US5786986A (en) * 1989-04-17 1998-07-28 International Business Machines Corporation Multi-level circuit card structure
GB2247782A (en) * 1990-09-05 1992-03-11 Marconi Gec Ltd A circuit board assembly
EP0603623A3 (en) * 1992-12-23 1995-05-03 Ibm Joining of layers and multi-layer circuit boards.
EP0603623A2 (en) * 1992-12-23 1994-06-29 International Business Machines Corporation Joining of layers and multi-layer circuit boards
GB2296604A (en) * 1994-12-24 1996-07-03 Bosch Gmbh Robert Electric device
EP0741504A3 (en) * 1995-05-05 1996-11-13 Bosch Gmbh Robert
GB2317503A (en) * 1996-09-20 1998-03-25 Motorola Inc Heat transfer apparatus suitable for use in a circuit board assembly
US5831826A (en) * 1996-09-20 1998-11-03 Motorola, Inc. Heat transfer apparatus suitable for use in a circuit board assembly
EP1781072A3 (en) * 2005-10-26 2007-05-16 Pentair Water Pool and Spa, Inc. Led pool and spa light

Also Published As

Publication number Publication date
GB8308882D0 (en) 1983-05-11
GB2137422B (en) 1986-10-29

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940330