CN1383358A - Packaging structure for electronic products - Google Patents

Abstract

The invention relates to a packaging structure for electronic products, which comprises a first circuit board, a second circuit board, a connecting element and a packaging structure, wherein the second circuit board has better heat transfer effect than the first circuit board and carries a part of electronic elements with large heating power, and the connecting element is used for electrically connecting the first circuit board and the second circuit board. The invention can improve the heat dissipation effect and the volume utilization.

Description

Packaging structure for electronic products

The invention relates to a packaging structure for electronic products.

Most of today's electronic components are welded on a printed circuit board (PCB) using Surface Mounting Technology (SMT). Taking DC to DC converter as an example, the main components configured on the circuit board are Electronic components include capacitors, resistors, inductors, transformers, diodes, metal-oxide-semiconductor field-effect transistors (MOSFETs), bare crystals, etc. When the DC-DC converter operates, these electronic components will generate heat of varying power, If the heat is not efficiently transferred to the outside world, excess heat can cause electronic components to fail, shut down the system, or even completely disable the entire system. For low-power electronic components, natural convection may be used to remove heat, while for high-power components, forced convection must be used to quickly remove heat. Regardless of whether it is natural convection or forced convection, the thermal resistance depends on the size of the heat dissipation area. Therefore, it is generally used as a heat dissipation mechanism to increase the heat dissipation area by attaching a heat sink. Conventional printed circuit boards are mainly composed of one or more layers of copper foil and a substrate made of organic substances such as epoxy and polyester. Because the thermal expansion coefficients of organic substances and copper foil are too different, and the points on the printed circuit board are not heated. Therefore, it often causes significant thermal stress, which degrades the function of electronic components. Taking the commonly used glass fiber epoxy resin substrate (FR-4 PCB) as an example, it still has the disadvantage of heat accumulation, and in actual use, the space and effect of adding a fan to dissipate heat are limited, and this kind of substrate is not easy to apply a heat sink The design of the heat sink needs to be special, so the cost is quite high. Moreover, after such a substrate is equipped with a heat sink, the heat dissipation effect is not satisfactory. Secondly, electronic components packaged in plastic molds (such as SO-08, SOT-23, chips, etc.) are not easy to dissipate heat further, so that the heat is excessively concentrated, resulting in a shortened product life.

In order to solve the above-mentioned shortcoming of thermal stress, a highly thermal conductive substrate has been developed. Commonly used high thermal conductive substrates include, for example, metal substrates and ceramic substrates. 1 is a schematic structural diagram of an existing metal substrate. The structure of the metal substrate 10 is sequentially composed of a base layer (base layer) 11, a dielectric layer (dielectric layer) 12 and a circuit layer (circuit layer) 13 from bottom to top, wherein the base layer The bottom layer 11 is usually aluminum, copper or other metals with a thickness of about 0.5 to 3.2 mm, and the circuit layer 13 is copper foil with a thickness of tens to hundreds of microns. The ceramic substrate uses aluminum oxide (Al ₂ O ₃ ) or beryllium oxide (BeO) as the base material, and its structure is in the prior art, so it will not be repeated here. Due to the good heat conduction effect of the high thermal conductivity substrate, it can overcome the above-mentioned shortcomings of thermal stress and heat concentration of the traditional printed circuit board. However, this kind of high thermal conductivity substrate also has the following disadvantages:

(1) The price of high thermal conductivity substrates is much higher than that of traditional printed circuit boards, for example, the price is about 10 times higher than that of glass fiber epoxy resin printed circuit board (FR-4 PCB) substrates;

(2) The heat conduction effect of the high thermal conductivity substrate is excellent, causing the heat of the electronic components with high heating power to be easily transferred to the electronic components with low heating power, thus affecting the function of the electronic components with low heating power.

The purpose of the present invention is to provide a packaging structure to improve the heat dissipation effect of electronic components.

Another object of the present invention is to provide a packaging structure to improve volume utilization and rational space allocation of electronic products.

Another object of the present invention is to provide a packaging structure to reduce the packaging cost of electronic products.

In order to achieve the above object, the packaging structure for an electronic product of the present invention includes: a first circuit board; a second circuit board, which has a better heat transfer effect than the first circuit board, and carries Some electronic components with high heating power; and a connection component, used to make the first circuit board and the second circuit board electrically connected.

The packaging structure for electronic products as described above, wherein the electronic product is a DC-DC converter (DC to DC converter).

As described in the packaging structure for electronic products, wherein the first circuit board is selected from one of copper clad substrates (Copper Clad Laminate, CCL), glass fiber epoxy resin substrates (FR-4 PCB) and thermoplastic substrates .

As described in the packaging structure for electronic products, wherein the second circuit board is a highly thermal conductive substrate.

As described above, the packaging structure for electronic products, wherein the high thermal conductivity substrate is a metal substrate or a ceramic substrate.

As described in the packaging structure for electronic products, wherein the electronic components with high heating power are selected from the group including transformers, MOSFETs, bare dies, diodes, windings and inductors.

As described in the package structure for electronic products, wherein the connecting element is a material with high thermal conductivity.

As described above, the packaging structure for electronic products, wherein the high thermal conductivity material is selected from one of the group consisting of copper, silver, and gold.

As described in the packaging structure for electronic products, wherein the second circuit board is located above the first circuit board.

As described in the packaging structure for electronic products, wherein the connecting element is a pillar for supporting the second circuit board.

As described in the packaging structure for electronic products, wherein the second circuit board is located on one side of the first circuit board.

As mentioned above, the packaging structure for electronic products, wherein the connecting element is in the shape of a line, a strip or a plate.

As described in the package structure for electronic products, wherein the second circuit board is further provided with a heat sink.

By adopting the above-mentioned technical scheme of the present invention, the packaging structure of the present invention has the following advantages: thermal stress is eliminated and heat dissipation is easy, and the heat rapidly transmitted from electronic components with large heating power will not affect electronic components with low power; the required high thermal conductivity The substrate area is much lower than that of the prior art, and the cost can be greatly reduced; since the relative positions of the first circuit board and the second circuit board can be configured according to the needs, it is more flexible for the volume utilization of the electrical equipment casing; its second The second circuit board can also be equipped with a radiator to improve the heat dissipation effect, thereby avoiding the shortcomings of the existing glass fiber epoxy resin substrate that is not easy to install and the heat dissipation effect is not good; due to its excellent heat dissipation performance, this is conducive to the development of high-power electronic products. and miniaturization.

In order to better understand the purpose, features and advantages of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 is a schematic diagram of a conventional metal substrate;

Fig. 2 (a) is the three-dimensional schematic view of the packaging structure of the first preferred embodiment of the present invention;

Fig. 2 (b) is the front view of the packaging structure of the first preferred embodiment of the present invention;

Fig. 3 (a) is the perspective view of the packaging structure of the second preferred embodiment of the present invention;

Fig. 3(b) is a front view of the packaging structure of the second preferred embodiment of the present invention.

2( a ) and ( b ) are respectively a perspective view and a front view of the packaging structure of the first preferred embodiment of the present invention. The packaging structure for electronic products of the present invention includes a first circuit board 20 , a second circuit board 30 and a connecting element 41 .

In order to prevent the heat emitted by some electronic components with large heating power from excessively affecting other electronic components, and to promote the flexibility of heat dissipation and space configuration and utilization, the main features of the present invention are: (1) The second circuit board 30 needs to be relatively large. The first circuit board 20 has a more ideal heat transfer effect. (2) Some electronic components with high heating power are arranged on the second circuit board 30 . Therefore, the first circuit board 20 can be selected from conventional printed circuit boards, such as copper clad substrates (Copper Clad Laminate, CCL), glass fiber epoxy resin substrates (FR-4 PCB) or thermoplastic substrates, and the second circuit board 30 It is a highly thermal conductive substrate, such as a commonly used metal substrate or ceramic substrate.

Taking the assembly of a DC-DC converter (DC to DC converter) as an example, the main electronic components required include capacitors, resistors, inductors, transformers, diodes, metal oxide semiconductor field effect transistors (MOSFETs), bare crystal (bare die), winding (winding), etc. In order to realize the purpose of the present invention, some electronic components 31 with large heating power can be configured on the second circuit board 30, and these electronic components 31 with large heating power include transformers, metal oxide semiconductor field effect transistors (MOSFET) , bare crystal, diode, inductor or winding, and the second circuit board 30 is mainly equipped with electronic components 21 with small heating power. Of course, according to circuit requirements, space configuration, cost and other factors, the first circuit board 20 can retain some electronic components (not shown) with high heating power, and the second circuit board 30 can also be equipped with some electronic components with small heating power (not shown). In this embodiment, the second circuit board 30 is located above the first circuit board 20, and then soldered to the contact pads 22, 32 of the first circuit board 20 and the second circuit board 20 with a copper column 41, so The pillars 41 of high thermal conductivity material are not only used for the electrical connection and thermal connection between the first circuit board 20 and the second circuit board 30 , but also have the effect of supporting the second circuit board 30 .

This kind of encapsulation structure can make the electronic components with large heating power conduct heat on the second circuit board 30 with excellent heat transfer effect. Since the back side of the second circuit board 30 is a flat plate, it is quite convenient to add a heat sink and the manufacturing cost is cheap. , and after attaching a heat sink (not shown) on the second circuit board 30, the heat on the second circuit board 30 can be quickly removed.

3( a ) and 3 ( b ) are respectively a three-dimensional schematic view and a front view of the packaging structure of the second preferred embodiment of the present invention. In this embodiment, except that the second circuit board 30 is located on one side of the first circuit board 20, the connecting element that makes the electrical connection between the first circuit board 20 and the second circuit board 30 is a strip 42 of high thermal conductivity material (It can also be linear or plate-shaped), and its working principle is the same as that of the first embodiment of the present invention.

To sum up, the main difference and progress between the packaging structure for electronic products of the present invention and the prior art lies in:

(1) The existing packaging structure that arranges electronic components on the same printed circuit board has the disadvantages of thermal stress and difficulty in heat dissipation; in addition, the existing packaging structure that arranges electronic components on the same high thermal conductivity substrate is not only expensive, but also large The heat rapidly dissipated from electronic components with heating power can easily affect the functions of low-power electronic components; and the packaging structure of the present invention can avoid the above-mentioned two kinds of shortcomings of the prior art.

(2) The packaging structure of the present invention for electronic products is to arrange the electronic components with large heating power on the high thermal conductivity substrate with excellent heat transfer effect, so the heat dissipation of the electronic components with large heating power is excellent, and the high thermal conductivity substrate The size of the substrate depends on the required electronic components with high heating power, so the required high thermal conductivity substrate area is much lower than that of the prior art, and the cost can be greatly reduced. Taking the DC-DC converter as an example, the packaging structure of the present invention can reduce the area of the high thermal conductivity substrate by about 20% compared with the packaging structure completely using the high thermal conductivity substrate. At the same time, the required area of the first circuit board 20 of the present invention is also smaller than that of the prior art which completely adopts the printed circuit board.

(3) The relative positions of the first circuit board 20 and the second circuit board 30 in the packaging structure of the electronic product of the present invention can be configured as required, so the utilization of the volume of the casing of the electrical equipment is more flexible.

(4) The second circuit board 30 of the packaging structure used for electronic products provided by the present invention can be further provided with a heat sink to improve the heat dissipation effect, and can avoid the problem that the conventional glass fiber epoxy resin substrate is not easy to install and the heat dissipation effect is not good. shortcoming.

(5) The packaging structure for electronic products provided by the present invention has good heat dissipation, which is very advantageous for the development of electronic products towards high power and miniaturization.

To sum up, the packaging structure for electronic products provided by the present invention has the advantages of good heat dissipation effect, good space utilization flexibility and low cost, and can avoid the disadvantages encountered in the prior art.

Claims (13)

1. A packaging structure for electronic products, characterized in that it comprises: a first circuit board; A second circuit board, which has a better heat transfer effect than the first circuit board, and carries some electronic components with high heating power; and A connecting element is used for electrically connecting the first circuit board and the second circuit board. 2. The packaging structure for electronic products according to claim 1, wherein the electronic product is a DC-DC converter. 3 . The package structure for electronic products according to claim 1 , wherein the first circuit board is selected from one of copper foil substrates, glass fiber epoxy resin substrates and thermoplastic substrates. 4 . 4 . The packaging structure for electronic products according to claim 1 , wherein the second circuit board is a substrate with high thermal conductivity. 5 . The packaging structure for electronic products according to claim 1 , wherein the high thermal conductivity substrate is a metal substrate or a ceramic substrate. 6. The packaging structure for electronic products as claimed in claim 1, wherein the electronic components with large heating power are selected from transformers, metal oxide semiconductor field effect transistors, bare crystals, diodes, windings and inductors ethnic group. 7. The packaging structure for electronic products as claimed in claim 1, wherein the connecting element is a material with high thermal conductivity. 8. The packaging structure for electronic products according to claim 7, wherein the high thermal conductivity material is selected from one of copper, silver and gold. 9. The packaging structure for electronic products as claimed in claim 1, wherein the second circuit board is located above the first circuit board. 10 . The packaging structure for electronic products according to claim 9 , wherein the connecting element is columnar and used to support the second circuit board. 11 . 11. The packaging structure for electronic products according to claim 1, wherein the second circuit board is located at one side of the first circuit board. 12 . The packaging structure for electronic products according to claim 11 , wherein the connecting element is in the shape of a line, a strip or a plate. 13 . 13. The packaging structure for electronic products according to claim 1, wherein a heat sink is further provided on the second circuit board.

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