WO2013171273A1

WO2013171273A1 - Electronic module, illuminating device and method for manufacturing such electronic module

Info

Publication number: WO2013171273A1
Application number: PCT/EP2013/060074
Authority: WO
Inventors: Xiaomian Chen; Jianghui YANG; Hao Li; Chuanpeng ZHONG
Original assignee: Osram Gmbh
Priority date: 2012-05-16
Filing date: 2013-05-15
Publication date: 2013-11-21
Also published as: CN103426993A

Abstract

The present invention relates to an electronic module (100), comprising electronic components (1), a substrate (2) and a heat sink (3), characterized in that the substrate (2) comprises a base (4) that is electrically insulative, and a first electric conducting layer (Al) and a second heat conducting layer (A2) that are arranged on two sides of the base (4), respectively, and the substrate (2) is in electrical connection with the electronic components (1) through the first electric conducting layer (Al) and is in fixed connection with the heat sink (3) through the second heat conducting layer (A2). In addition, the present invention further relates to an illuminating device comprising such electronic module and a method for manufacturing such electronic module.

Description

Electronic Module, illuminating Device and Method for

Manufacturing such Electronic Module

Technical Field

The present invention relates to an electronic module, an il^¬ luminating device comprising such electronic module and a method for manufacturing such electronic module. Background Art

Large-power components such as high-luminance LED light sources are widely used in current electronic devices, wherein these large-power components can be mounted on a metal-based circuit board (MCPCB) or a ceramic-based circuit board through a chip on board (COB) technology, and further the circuit board and a heat sink are fixed together to con^¬ stitute a complete electronic module. Thus, how to improve the heat dissipating effect of such electronic module becomes an important research direction. As to an electronic module having a circuit board that takes metal such as aluminum as a base, an insulating layer usually should be disposed between a circuit layer and the metal base, and the insulating layer has a thermal conductivity of only 1-4 W/K*m. Moreover, a thermal interface material usu- ally is also additionally arranged between the metal base and a heat sink connected therewith, which further increases thermal resistance inside the electronic module and directly affects the heat dissipating effect of the electronic module. As to an electronic module having a circuit board that takes ceramic as a base, due to restriction of properties of the ceramic, it has a thermal conductivity of only about 30 W/K*m, which is far less than the thermal conductivity of metal, as a result, such circuit board has a relatively big spread thermal resistance, which causes it hard for heat to be transferred from one side to the other side of the circuit board .

Summary of the Invention

Therefore, one object of the present invention lies in pro^¬ viding an electronic module that is easily manufactured, has a low cost and realizes good heat dissipating effect in a precondition of assuring normal operation of electronic components located therein.

The electronic module in accordance with the present inven^¬ tion comprises electronic components, a substrate and a heat sink, characterized in that the substrate comprises a base that is electrically insulative, and a first electric con^¬ ducting layer and a second heat conducting layer that are arranged on two sides of the base, respectively, and the sub^¬ strate is in electrical connection with the electronic compo- nents through the first electric conducting layer and is in thermal connection with the heat sink through the second heat conducting layer.

The concept of the present invention lies in reducing, as much as is possible, thermal resistance between the elec- tronic components and the heat sink so as to improve the heat dissipating effect of the electronic module. In order to re^¬ duce the thermal resistance between the electronic components and the heat sink and to assure insulating performance there^¬ between, the substrate in accordance with the present inven- tion is specially configured as a "sandwich-shaped" substrate formed by clamping the insulating layer with the first electric conducting layer on top and the second heat conducting layer at bottom. As a result, an electrical connection path can be provided through the first electric conducting layer in connection with the electronic components, at the same time, heat generated by the electronic components during op^¬ eration is conducted to the base, and further the heat in the base is transferred to the heat sink through a heat conduct^¬ ing path having a small thermal resistance by using the sec- ond heat conducting layer arranged to face the first electric conducting layer.

In accordance with one preferred solution of the present in^¬ vention, the first electric conducting layer is a metal layer. In addition, preferably, the second heat conducting layer is a metal layer. Since metals have good electrical conductivity and thermal conductivity, and property of easy connection, metal layers are provided on two sides of the base that is electrically insulative, respectively.

In accordance with one preferred solution of the present in- vention, the first electric conducting layer or the second heat conducting layer is the metal layer that is formed through one process selected from sputtering, evaporation, thick film printing and chemical deposition. The first electric conducting layer and/or the second heat conducting layer is arranged on two sides of the base in an appropriate man^¬ ner, that is to say, the two sides of the base opposite each other are metalized.

In accordance with one preferred solution of the present in^¬ vention, the first electric conducting layer or the second heat conducting layer has a thickness of 10-100μιη. Preferably, the base has a thickness of less than 1mm.

In accordance with one preferred solution of the present in^¬ vention, the first electric conducting layer is configured as a printed circuit layer. Accordingly, the electronic compo- nents can be in electrical connection with each other in virtue of the electrical conductivity of the first electric con^¬ ducting layer.

In accordance with one preferred solution of the present in^¬ vention, the substrate is fixed on the heat sink through the second heat conducting layer.

In accordance with one preferred solution of the present in^¬ vention, the heat sink has a metal contact surface configured to be in contact with the second heat conducting layer. Particularly, the second heat conducting layer and the metal contact surface are in soldered connection with each other. When the heat sink is configured to have the metal contact surface for contacting the second heat conducting layer, on one hand, thermal resistance between the heat sink and the substrate can be reduced, and on the other hand, the heat sink and the second heat conducting layer can be fixedly sol^¬ dered together through a soldering process so as to fix the heat sink and the substrate relatively.

In accordance with another preferred solution of the present invention, the base is made from an electric-insulating and heat-conducting material. The base disposed between the first electric conducting layer and the second heat conducting layer not only can electrically insulate the two metal layers but also can realize heat conduction between the two metal layers . Preferably, the base is made from a ceramic material. For in^¬ stance, an appropriate material such as AI₂O₃ or A1N can be chosen to manufacture the base of ceramic.

In accordance with another preferred solution of the present invention, the base is configured to be flake-shaped. In or^¬ der to further reduce the thermal resistance of the sub^¬ strate, a straight heat conducting path of heat between the first electric conducting layer and the metal contact surface of the heat sink can be reduced as much as is possible. Com- pared with bases with other shapes, the base configured to be flake-shaped has a relatively small thermal resistance in a vertical direction. In a preferred situation, the base has a thickness of less than 1mm.

In accordance with one preferred solution of the present in- vention, the heat sink is a vapor chamber. The vapor chamber is a vacuum chamber that has an inner wall with a fine struc^¬ ture and it is usually made from a metal such as copper. The vapor chamber has a design principle and an operation mode similar to that of heat pipe, but since the vapor chamber has the characteristic of quick heat dissipation, that is, it has a relatively small conduct thermal resistance in a vertical direction, e.g. less than 0.01K/W, and a relatively small spread thermal resistance in a horizontal direction, e.g. less than 0.02K/W, and then it is mainly used for dissipating heat of high-power components such as high-luminance LED chips. In different application environments, the shape of the vapor chamber can be flexibly changed to meet different structure requirements.

In addition, the present invention further relates to an il- luminating device, comprising the above electronic module, wherein the electronic components comprise LED chips as light sources. The illuminating device mounted with such electronic module, in a situation of using large-power LED chips as light sources, also can realize good heat dissipation to as^¬ sure normal operation of the illuminating device. Further, the present invention further relates to a method for manufacturing the above electronic module, characterized by comprising steps of: a) providing a substrate that comprises a base that is elec^¬ trically insulative, and a first electric conducting layer and a second heat conducting layer that are arranged on two sides of the base, respectively, b) providing electronic components and a heat sink, and c) electrically connecting the first electric conducting layer and the electronic components, and fixedly connecting the second heat conducting layer and the heat sink.

The difference of the method in accordance with the present invention from methods of manufacturing conventional elec^¬ tronic modules lies in that the first electric conducting layer and the second heat conducting layer are arranged on two sides of the base that is electrically insulative, re^¬ spectively, thus, the first electric conducting layer can be electrically connected with the electronic components by tak^¬ ing advantage of its electrical conductivity, and since there is also the second heat conducting layer facing the first electric conducting layer and in thermal connection with the heat sink, in virtue of the thermal conductivity of the sec^¬ ond heat conducting layer, the second heat conducting layer is in thermal connection with the electronic components through the first electric conducting layer and the base, and further the thermal connection between the electronic compo^¬ nents and the heat sink is realized.

In accordance with one preferred solution of the present in^¬ vention, the step a) further comprises steps of: al) providing a base that is electrically insulative; and a2) metalizing two surfaces of the base opposite each other to obtain the first electric conducting layer and the second heat conducting layer.

In accordance with one preferred solution of the present in- vention, in the step a2) metal coatings are formed on two sides of the base through a sputtering process, and the metal coating on one side thereof is processed through an addition process to form the first electric conducting layer, and the metal coating on the other side thereof is used as the second heat conducting layer.

Brief Description of the Drawings

The accompanying drawings constitute a part of the present Description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention and are used to de^¬ scribe the principles of the present invention together with the Description. In the accompanying drawings the same compo^¬ nents are represented by the same reference numbers. As shown in the drawings : Fig. 1 is a cross-sectional view of a first embodiment of an electronic module in accordance with the present invention; and Fig. 2 is a flow chart of manufacturing the electronic module in accordance with the present invention.

Detailed Description of the Embodiments

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, direc^¬ tional terminology, such as "top", "bottom", "upper",

"lower", is used in reference to the orientation of the fig- ures being described. Because components of embodiments of the present invention can be positioned in a number of dif^¬ ferent orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. It is to be understood that the features of the various exem^¬ plary embodiments described herein may be combined with each other, unless specifically noted otherwise.

Fig. 1 shows a first embodiment of an electronic module 100 in accordance with the present invention. The electronic mod- ule 100 comprises electronic components 1, a substrate 2 and a heat sink 3. In order to reduce thermal resistance from a plurality of electronic components 1 to the heat sink 3, the substrate 2 having a small thermal resistance, and especially small conduct thermal resistance and spread thermal resis- tance, is particularly configured. Such substrate 2 is based on the base 4 having electrically insulating property, and two surfaces of the base 4 opposite each other are provided with metallic first electric conducting layer Al and second heat conducting layer A2, respectively. Based on the electri- cal conductivity and the thermal conductivity of metal, in the present embodiment, the first electric conducting layer Al is mainly used as an electric conducting layer for electrically connecting the electronic components 1 with each, and the second heat conducting layer A2 is used as a heat conducting layer between the base 4 and the heat sink 3, as a result, heat generated by a plurality of electronic compo^¬ nents 1 in operation can be conducted, as much as is possi^¬ ble, through the substrate 2 to the heat sink 3.

In order to assure that the electronic components 1 are merely in electrical connection with the printed circuit, the base 4 that is electrically insulative in the present embodi^¬ ment is particularly configured as a ceramic base having thermal conductivity and insulating property. Such base 4 can comprise substances such as AI₂O₃ and AIN. The first electric conducting layer Al and the second heat conducting layer A2 can be formed, in a form of metal film, on two sides of the base 4, respectively, through processes such as sputtering, evaporation, thick film printing and chemical deposition, wherein the first electric conducting layer Al is configured as a printed circuit layer for electrical connection with the electronic components 1. In addition, in order to improve the heat dissipating effect of the electronic module 100 in ac^¬ cordance with the present invention, the heat sink 3 is par^¬ ticularly configured to have metal surfaces. The heat sink 3 in the present embodiment is preferably configured as a vapor chamber .

Functions of the first electric conducting layer Al lie in that, on one hand, the electronic components 1 can be in electrical connection with the first electric conducting layer Al and can be electrically connected with each other in virtue of the first electric conducting layer Al ; and on the other hand, the plurality of electronic components 1 also can transfer the heat generated during operation through the first electric conducting layer Al to the base 4 that is electrically insulative. Functions of the second heat con^¬ ducting layer A2 lie in that, on one aspect, heat from the electronic components 1 can be uniformly and highly- effectively transferred to the heat sink 3 through the second heat conducting layer A2 ; and on the other aspect, by means of the second heat conducting layer A2, the whole substrate 2 can be in fixed connection with a metal contact surface A3 of the heat sink 3.

In the first embodiment shown in Fig. 1, the plurality of electronic components 1 are electrically connected with each other through fly lines 6, and the second heat conducting layer A2 and the metal contact surface A3 are soldered to- gether through a soldering paste. In order to further reduce the thermal resistance of the electronic module 100, espe^¬ cially the thermal resistance of the substrate 2, a ceramic body configured as flake-shaped and having a thickness of less than 1mm is used as the base 4 in the present embodi- ment . The electronic components 1 can be LED chips, capaci^¬ tors, resistors or other electronic parts.

In one embodiment not shown, the vapor chamber can be re^¬ placed by other heat dissipating devices.

Fig. 2 is a flow chart of manufacturing the electronic module 100 in accordance with the present invention. How to manufac^¬ ture the substrate 2 of the electronic module 100 in accor- dance with the present invention is shown in the first three blocks, and in the fourth block, assembling the electronic components 1, the substrate 2 and the heat sink 3 into the electronic module is shown. Such manufacturing method is sim- pie and easy, and can yield large-scale production at a low cost .

In the first block, firstly a flake-shaped ceramic base 4 is provided. Such base 4 have characteristics of low thermal re^¬ sistance and high insulating performance. In the second block, an upper surface and a lower surface of the base 4 op^¬ posite each other are metalized through an appropriate proc^¬ ess such as sputtering, evaporation, thick film printing and chemical deposition. As a result, a "sandwich" structure can be formed. Subsequently, the metal coating on the upper sur- face of the base 4 is processed to form a normal printed cir^¬ cuit layer. The printed circuit layer can be manufactured through an addition process, and this process usually com^¬ prises the following steps: covering a optical resist on the metal coating, developing through an optical etching process to expose positions for the printed circuit board, and then filling a metal such as copper having an appropriate thickness into preset exposed positions through plating so as to form a complete circuit layout, and subsequently, conducting an etching process again, i.e. so-called "decoating", to re- move the optical resist and metal film covered thereby. Thus, the substrate 2 as shown in the third block can be obtained.

In the fourth block, the second heat conducting layer A2 used as a heat conducting layer and the heat sink 3 having the metal contact surface A3, particularly preferably configured as a vapor chamber, is fixedly thermally connected through a soldering paste 5. On the other side, a plurality of (possi^¬ bly one) electronic components 1 also can be fixed in a sol- dering manner on the first electric conducting layer Al used as electric conducting layer, and the plurality of electronic components 1 can be electrically connected with each other through fly lines 6. In addition, while a particular feature or aspect of an embodiment of the invention may have been disclosed with re^¬ spect to only one of several implementations, such feature or aspect may be combined with one or more other features or as^¬ pects of the other implementations for any given or particu- lar application. Furthermore, to the extent that the terms

"include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise" . The above is merely preferred embodiments of the present in^¬ vention but not to limit the present invention. For the per^¬ son skilled in the art, the present invention may have vari^¬ ous alterations and changes. Any alterations, equivalent sub^¬ stitutions, improvements, within the spirit and principle of the present invention, should be covered in the protection scope of the present invention.

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List of reference signs

1 electronic component

2 substrate

3 heat sink

4 base

5 soldering paste

6 fly line

Al first electric conducting layer

A2 second heat conducting layer A3 metal contact surface

100 electronic module

Claims

1. An electronic module (100), comprising electronic compo^¬ nents (1), a substrate (2) and a heat sink (3), characterized in that the substrate (2) comprises a base (4) that is elec^¬ trically insulative, and a first electric conducting layer (Al) and a second heat conducting layer (A2) that are arranged on two sides of the base (4), respectively, and the substrate (2) is in electrical connection with the electronic components (1) through the first electric conducting layer (Al) and is in thermal connection with the heat sink (3) through the second heat conducting layer (A2) .

2. The electronic module (100) according to Claim 1, char^¬ acterized in that the first electric conducting layer (Al) is a metal layer.

3. The electronic module (100) according to Claim 1, char^¬ acterized in that the second heat conducting layer (A2) is a metal layer.

4. The electronic module (100) according to Claim 2 or 3, characterized in that the first electric conducting layer

(Al) or the second heat conducting layer (A2) is the metal layer that is formed through one process selected from sput^¬ tering, evaporation, thick film printing and chemical deposition.

5. The electronic module (100) according to Claim 2 or 3, characterized in that the first electric conducting layer (Al) or the second heat conducting layer (A2) has a thickness of 10-100μπι.

6. The electronic module (100) according to Claim 2, char- acterized in that the first electric conducting layer (Al) is configured as a printed circuit layer.

7. The electronic module (100) according to Claim 2 or 3, characterized in that the substrate (2) is fixed on the heat sink (3) through the second heat conducting layer (A2) .

8. The electronic module (100) according to Claim 7, char^¬ acterized in that the heat sink (3) has a metal contact sur^¬ face (A3) in contact with the second heat conducting layer (A2) .

9. The electronic module (100) according to Claim 8, char^¬ acterized in that the second heat conducting layer (A2) and the metal contact surface (A3) are in soldered connection with each other.

10. The electronic module (100) according to Claim 1, char- acterized in that the base (4) is made from an electric- insulating and heat-conducting material.

11. The electronic module (100) according to Claim 10, char- acterized in that the base (4) is made from a ceramic mate- rial .

12. The electronic module (100) according to Claim 1, char- acterized in that the base (4) is configured to be flake- shaped .

13. The electronic module (100) according to Claim 12, char- acterized in that the base (4) has a thickness of less than lmm.

14. The electronic module (100) according to Claim 2 or 3, characterized in that the heat sink (3) is a vapor chamber.

15. An illuminating device, characterized by comprising the electronic module (100) according to any of Claims 1-14, wherein the electronic components (1) comprise LED chips as light sources.

16. A method for manufacturing the electronic module (100) according to any of Claims 1-14, characterized by comprising steps of: a) providing a substrate (2) that comprises a base (4) that is electrically insulative, and a first electric conducting layer (Al) and a second heat conducting layer (A2) that are arranged on two sides of the base (4), respectively, b) providing electronic components (1) and a heat sink (3), and c) electrically connecting the first electric conducting layer (Al) and the electronic components (1), and fixedly connecting the second heat conducting layer (A2) and the heat sink (3) .

17. The method according to Claim 16, characterized in that the step a) further comprises steps of: al) providing a base (4) that is electrically insulative; and a2) metalizing two surfaces of the base (4) opposite to each other to obtain the first electric conducting layer (Al) and the second heat conducting layer (A2) .

18. The method according to Claim 17, characterized in that in the step a2) metal coatings are formed on two sides of the base (4) through a sputtering process, and the metal coating on one side thereof is processed through an addition process to form the first electric conducting layer (Al), and the metal coating on the other side thereof is used as the second heat conducting layer (A2) .