CN101140915A - Heat dissipation substrate for electronic components - Google Patents

Abstract

A heat dissipation substrate of an electronic component comprises a first metal layer, a second metal layer and a heat conducting polymer dielectric insulating material layer. The surface of the first metal layer carries the electronic components (e.g., Light Emitting Diode (LED) components). The heat-conducting polymer dielectric insulating material is laminated between the first metal layer and the second metal layer to form physical contact, and the interface between the first metal layer and the second metal layer comprises at least one micro-rough surface (the roughness Rz is more than 7.0). The micro rough surface comprises a plurality of nodular protrusions, the particle sizes of the nodular protrusions are mainly distributed between 0.1 and 100 micrometers, the heat conduction coefficient of the heat conduction high polymer dielectric insulating material layer is greater than 1W/m.K, the thickness of the heat conduction high polymer dielectric insulating material layer is less than 0.5mm, and the heat conduction high polymer dielectric insulating material layer comprises (1) fluorine-containing high polymer, the melting point of the fluorine-containing high polymer is higher than 150 ℃, and the volume percentage of the fluorine-containing high polymer is between 30 and 60 percent; and (2) heat-conducting filler which is dispersed in the fluorine-containing high molecular polymer and has the volume percentage of 40-70%.

Description

Heat dissipation substrate for electronic components

technical field

The invention relates to a heat dissipation substrate, in particular to a heat dissipation substrate used for heat dissipation of electronic components.

Background technique

In recent years, white light-emitting diodes (LEDs) are the most promising emerging products that attract global attention. It has the advantages of small size, low power consumption, long life and good response speed, etc., and can solve the problems that incandescent bulbs were difficult to overcome in the past. LEDs are used in display backlights, mini projectors, lighting and automotive light sources and other markets are gaining more and more attention.

At present, countries such as Europe, America and Japan are actively developing white light-emitting diodes as new light sources for lighting in this century based on the consensus of energy conservation and environmental protection. In addition, many of Tongjia's energy sources are currently imported, making its development in the lighting market extremely valuable. According to expert evaluation, if Japan replaces all incandescent lamps with white light-emitting diodes, it can save the power generation of 1 to 2 power plants every year, indirectly reduce fuel consumption by 1 billion liters, and emit 100 million liters of electricity during power generation. Carbon dioxide will also be reduced, thereby inhibiting the greenhouse effect. Based on this, advanced countries such as Europe, America and Japan have invested a lot of manpower to promote research and development. It is expected that in the next ten years, traditional lighting fixtures can be generally replaced.

However, for high-power LEDs for lighting, only about 15-20% of the power input to the LED is converted into light, and the remaining 80-85% is converted into heat. If the heat cannot be dissipated to the environment in a timely manner, the interface temperature of the LED element will be too high, which will affect its luminous intensity and service life. Therefore, the problem of thermal management of LED components has been paid more and more attention.

Whether it is a display backlight or general lighting, it is common to assemble a plurality of LED elements on a circuit substrate. In addition to playing the role of carrying the LED module, the circuit substrate also needs to provide the function of heat dissipation. The operating current of traditional LEDs is only about 20mA. Because the heat is not large, the heat dissipation problem is not serious. Therefore, it is only necessary to use a copper foil printed circuit board (PCB) for general electronics. However, with the widespread application of high-power LEDs, their operating current can reach more than 1A, and the conventional printed circuit board (heat dissipation coefficient of about 0.3W/m·K) using glass fiber FR4 surface with copper foil is not enough to meet the heat dissipation requirements.

Contents of the invention

The main purpose of the present invention is to provide a heat dissipation substrate, which has excellent heat dissipation characteristics, and has both high-voltage dielectric insulation characteristics, flexible mechanical structure characteristics, and a gap between the metal layer and the thermally conductive polymer dielectric insulating material layer. The excellent joint tensile strength can provide applications such as high-power components such as LEDs (such as foldable mobile phones).

In order to achieve the above purpose, the present invention discloses a heat dissipation substrate for electronic components, which includes a first metal layer, a second metal layer and a thermally conductive polymer dielectric insulating material layer. The surface of the first metal layer bears the electronic components (such as light emitting diode (LED) components). The thermally conductive polymer dielectric insulating material layer is stacked between the first metal layer and the second metal layer and forms physical contact, and the thermally conductive polymer dielectric insulating material layer is connected to the first and second metal layers The interface contains at least one micro-rough surface (roughness Rz greater than 7.0, according to JIS B 06011994). The micro-rough surface contains a plurality of nodule-like protrusions, and the particle size of the nodule-like protrusions is mainly distributed between 0.1 and 100 microns, and the thermal conductivity of the thermally conductive polymer dielectric insulating material layer is greater than 1W/m K, with a thickness of less than 0.5 mm, and containing: (1) a fluorine-containing high molecular polymer with a melting point higher than 150°C and a volume percentage between 30-60%; and (2) a thermally conductive filler dispersed in the Among the above-mentioned fluorine-containing high molecular polymers, and its volume percentage is between 40-70%.

Preferably, the fluorine-containing polymer can be selected from polyvinylidene fluoride (Poly Vinylidene Fluoride; PVDF) or polyethylene-tetrafluoroethylene (polyethylenetetrafluoroethylene; PETFE), and the melting point is preferably greater than 150 ° C, and More than 220°C is more preferable. The thermally conductive filler can be selected from ceramic thermally conductive materials such as nitrides and oxides.

The heat dissipation substrate of the present invention can also be cross-linked and cured by irradiating the heat-conducting polymer dielectric insulating material layer through 0-20 Mrad of radiation. In addition to having good heat conduction and insulation effects, if the first metal layer and the second The thicknesses of the two metal layers are made to be less than 0.1mm and 0.2mm respectively, and the thickness of the thermally conductive polymer dielectric insulating material layer is less than 0.5mm (0.3mm is better), which can be formed by bending a 1cm wide test substrate. In the flexural test of a 5mm diameter cylinder, there will be no cracks or cracks on the surface, so it can be used for folding product applications.

In addition, because fluorine-containing polymer materials generally have a relatively high melting point (for example, PVDF is about 165°C, PETFE is about 240°C) and has flame retardant properties, can withstand high temperatures, and is not easy to catch fire, so it has more safety application value.

Description of drawings

FIG. 1 illustrates a heat dissipation substrate according to an embodiment of the present invention.

Detailed ways

Referring to FIG. 1 , an LED element 10 is carried on a heat dissipation substrate 20 . The heat dissipation substrate 20 includes a first metal layer 21 , a second metal layer 22 and a thermally conductive polymer dielectric insulating material layer 23 stacked between the first metal layer 21 and the second metal layer 22 . The LED element 10 is disposed on the surface of the first metal layer 21, and the interface between the first and second metal layers 21 and 22 forms a physical contact with the thermally conductive polymer dielectric insulating material layer 23, and wherein At least one interface is a micro-rough surface, and the micro-rough surface includes a plurality of tumor-like protrusions, and the particle diameters of the nodule-like protrusions are mainly distributed between 0.1 and 100 microns, thereby increasing the tensile strength between them.

The manufacturing method of the above-mentioned heat dissipation substrate 20 is exemplified as follows: the feed temperature of the batch mixer (HAAKE-600P) is set at the material melting point (Tm) + 20°C, and the formula for the heat-conducting polymer dielectric insulating material layer 23 is added Premix (the raw materials are placed in a steel cup and stirred evenly with a measuring spoon). Initially, the rotational speed of the kneader was 40rpm, and after 3 minutes, the rotational speed was increased to 70rpm, and the kneading was continued for 15 minutes before feeding, and a heat-dissipating composite material with heat-dissipating properties was formed.

Put the above-mentioned heat dissipation composite material into a mold whose outer layer is a steel plate and the middle thickness is the required thickness (for example, 0.15mm) in a symmetrical manner up and down. Put a layer of Teflon release cloth on the upper and lower sides of the mold, and preheat it for 5 minutes. Then press for 15 minutes (operating pressure 150kg/cm ² , temperature is the same as the kneading temperature), and then form a heat dissipation sheet with a thickness of 0.15mm.

Place the first metal layer 21 and the second metal layer 22 above and below the heat dissipation sheet and press together again, preheat for 5 minutes, and then press for 5 minutes (operating pressure 150kg/cm ² , temperature is the same as that of kneading temperature), form the heat dissipation substrate 20 with the thermally conductive polymer dielectric insulating material layer 23 in the middle, and the first metal layer 21 and the second metal layer 22 bonded up and down.

Table 1 shows the experimental results of tensile force and withstand voltage tests with different roughnesses, wherein the thermally conductive polymer dielectric insulating material layer 23 uses polyvinylidene fluoride (Poly Vinylidene Fluoride; PVDF) (melting point about 165° C.) as the base material, And the thermal conductive filler aluminum oxide (Al ₂ O ₃ ) is dispersed in the PVDF, and the volume percentages of the two are 40% and 60% respectively. In this embodiment, the thickness of the thermally conductive polymer material layer 23 is less than 0.3 mm. The tensile test conforms to the Japanese JIS C6481 specification to test the peel strength between interfaces.

Table I

serial number metal foil Thickness of thermally conductive polymer layer (mm) Tensile force(N/cm) Thermal conductivity (W/m K) Withstand voltage test type Specification Roughness (Rz) 1 Copper foil 1oz 7.0-9.0 0.21 14.3 1.7 ＞5kV 2 Copper foil 2oz 9.5-11.5 0.24 16.8 1.6 ＞5kV 3 Copper foil 4oz 10.0-12.0 0.22 17.5 1.7 ＞5kV 4 Copper-nickel foil 1oz 9.5-11.5 0.23 16.9 1.7 ＞5kV 5 Copper-nickel foil 2oz 10.0-12.0 0.23 17.8 1.6 ＞5kV 6 Nickel foil 1oz 10.0-12.0 0.24 18.1 1.6 ＞5kV control group Copper foil 1oz 3.0-4.5 0.23 7.5 1.6 ＞5kV

It can be seen from Table 1 that the surface roughness (Rz) of the control group is between 3.0 and 4.5, which is smaller than that of the experimental group numbered 1-6, and its pulling force of 7.5N/cm is much smaller than that of the experimental group numbered 1-6 ( At least greater than 8.0N/cm). It is obvious that a larger surface roughness can increase the peeling strength between the thermally conductive polymer dielectric insulating material layer 23 and the first and second metal layers 21 and 22 . In addition, all experimental groups can pass the withstand voltage test of 5kV (or at least greater than 3kV), and their thermal conductivity is greater than 1.0W/m·K.

Table 2 is a test comparison table for different types of polymers.

Table II

serial number   High Molecular Polymer Thickness of thermally conductive polymer material layer (mm) Thermal conductivity (W/m K) Tensile force(N/cm) Flexibility (5mm) Tin pot test (260℃) Withstand voltage test 1 PVDF 0.22 1.6 14.5 PASS PASS ＞5kV 2 PETFE 0.24 1.7 16.8 PASS PASS ＞7kV Control group 1 HDPE 0.21 1.7 15.7 PASS FAIL ＜2kV Control group 2 EPOXY 0.20 1.6 22.1 FAIL PASS ＞3kV

The experimental groups No. 1 and No. 2 used PVDF and PETFE (Tefzel ^TM ) as the polymer base material respectively, and alumina (Al ₂ O ₃ ) was used as the thermally conductive filler, and the polymers of the control groups 1 and 2 were made of fluorine-free high Molecular polyethylene (HDPE) and epoxy resin (EPOXY). The volume percentages of polymers and thermally conductive fillers in the above-mentioned experimental group and control group are both 40% and 60%, and copper foils with a roughness Rz of 7.0-9.0 are used as the first and second metal layers.

The epoxy resin (EPOXY) control group includes liquid epoxy resin, Novolac resin, dicyandiamide, urea catalyst, and aluminum oxide (Al ₂ O ₃ ). Described liquid epoxy resin adopts the model DER331 product of Dow Chemical Company (Dow Chemical Company); Novolac resin adopts the model DEN438 product of Dow Chemical Company; Dicyandiamide adopts Dyhard 100S of Degussa Fine Chemicals Company; The urea The catalyst is Dyhard UR500 from Degussa Fine Chemicals; the aluminum oxide has a particle size between 5 and 45 microns, which is produced by Denki Kagaku Kogyo Kabushiki Kaisya.

The epoxy resin (EPOXY) can be prepared as follows: mix 50 parts of DER331 and 50 parts of DEN438 in a resin kettle at 80° C. until a homogeneous solution is formed. Next, 10 parts of Dyhard 100S and 3 parts of Dyhard UR300 were added to the resin pot and mixing was continued for 20 minutes at 80°C. Afterwards, 570 parts of Al ₂ O ₃ filler was added into the resin pot and the mixing was continued until the filler was completely dispersed in the resin to form a resin slurry. Vacuum remove the gas contained in the resin paste for 30 minutes, then place the resin paste on the surface of a copper foil, and place another copper foil on the surface of the resin paste to form a copper foil/resin paste/copper foil composite structure. The copper foil/resin pulp/copper foil composite structure was placed in a 3mm thick metal frame, and a rubber roller was used to planarize the surface of the copper foil. The composite structure (together with the metal frame) was placed in a 130°C oven for 1 hour to pre-cure. Afterwards, the composite structure together with the metal frame was placed in a vacuum hot press (vacuum degree of 10 torr, pressure of 50 kg/cm ² ), and further cured at a temperature of 150° C. for 1 hour. The composite structure was cooled to below 50° C. under a pressure of 50 kg/cm ² , and the composite structure was removed from the hot press.

The test substrate of described PVDF and PETFE experimental group and HDPE and EPOXY control group is through following test:

1. Flexibility: bend the 1cm wide test substrate into a 5mm diameter cylinder, and there should be no breaks or cracks on the surface.

2. Tin furnace test: place the test substrate in a tin furnace at 260°C for 5 minutes, and there should be no blisters or other abnormal appearance on the surface.

3. Tensile (peel strength) test: conducted in accordance with Japanese Industrial Standard JIS C6481.

4. Dielectric strength (dielectric breakdown voltage) test: that is, the withstand voltage test, which is carried out in accordance with the Japanese Industrial Standard JIS C2110.

It can be seen from Table 2 that the experimental group of fluorine-containing polymers PVDF and PETFE has good flexibility and high temperature resistance, and can also withstand high voltages above 5kV through the withstand voltage test. On the other hand, the control group 1 using HDPE as the polymer passed the flexibility test, but it failed the 260°C tin furnace high temperature test, and its withstand voltage was less than 2kV, which was significantly lower than that of the experimental groups 1 and 2. As for the control group 2 using EPOXY as the polymer, although it can pass the high-temperature tin oven test, it has high hardness and is not flexible.

In addition, the above-mentioned fluorine-containing materials of PVDF and PETFE are non-flammable and non-combustible (according to UL 94V-0), and compared with HDPE and EPOXY, they can provide safer applications.

The volume percentages of the fluorine-containing high molecular polymer and the thermally conductive filler can be adjusted to some extent while still maintaining the same characteristics. Preferably, the volume percentage of the fluorine-containing high molecular polymer is between 30-60%; and the volume percentage of the thermally conductive filler is between 40-70%, and especially the percentage is between 50-65%. good.

In addition to the above material selection, thermally conductive polymers can also be polytetrafluoroethylene (poly (tetrafluoroethylene); PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (tetrafluoroethylene-hexafluoro-propylene copolymer; FEP), ethylene- Tetrafluoroethylene copolymer (ethylene-tetrafluoroethylene copolymer; ETFE), perfluoroalkoxy modified tetrafluoroethylene (perfluoroalkoxymodified tetrafluoroethylenes; PFA), poly (chlorotri-fluorotetrafluoroethylene) (poly (chlorotri-fluorotetrafluoroethylene); PCTFE) , vinylidene fluoride-tetrafluoroethylene copolymer (vinylidene fluoride-tetrafluoroethylene copolymer); VF-2-TFE), polyvinylidene fluoride (poly(vinylidene fluoride)), tetrafluoroethylene-perfluorodioxane Pentene copolymer (tetrafluoroethylene-perfluorodioxole copolymers), vinylidenefluoride-hexafluoropropylene copolymer (vinylidenefluoride-hexafluoropropylene copolymer), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer (vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer), and tetrafluoroethylene-perfluoromethylvinyl ether (tetrafluoroethylene-perfluoromethylvinylether) plus cured domain monomer terpolymer (cure site monomer terpolymer), etc.

The thermally conductive filler can be selected from nitride or oxide. The nitride includes zirconium nitride (ZrN), boron nitride (BN), aluminum nitride (Aluminum nitride; AlN), and silicon nitride (Siliconnitride; SiN). The oxide includes aluminum oxide (Aluminum oxide; Al ₂ O ₃ ), magnesium oxide (Magnesium oxide; MgO), zinc oxide (Zinc oxide; ZnO), titanium dioxide (Titaninum dioxide; TiO ₂ ), and the like.

In addition, if it is applied to a high-power light-emitting element of an LED, the first metal layer 21 carrying the LED element 10 can be made of copper, so that the relevant circuits of the LED element can be made, and the second metal layer 22 at the bottom can be made of copper. , aluminum or its alloys.

The heat dissipation substrate of the present invention not only has the characteristics of high thermal conductivity, high voltage resistance, and high temperature resistance, but also has high tensile strength and flexibility, so it can be applied to heat dissipation of LED modules for current lighting, and can even be used for notebook computers , mobile phones and other folding heat dissipation applications.

The technical content and technical features of the present invention have been disclosed above, but those skilled in the art may still make various substitutions and modifications based on the teaching and disclosure of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to the contents disclosed in the embodiments, but should include various replacements and modifications that do not depart from the present invention, and should be covered by the appended claims.

Claims (18)

1. the heat radiation substrate of an electronic component comprises:

One the first metal layer, surface thereof carry described electronic component;

One second metal level; And

One heat-conducting polymer dielectric insulation material layer, be stacked between the described the first metal layer and second metal level and form physics and contact, the interface of described heat-conducting polymer dielectric insulation material layer and described first and second metal levels comprises at least one roughness Rz greater than 7.0 slightly rough surface, described slightly rough surface comprises a plurality of warty protrusions, and the particle diameter of described warty protrusion mainly is distributed between 0.1 to 100 micron, the conductive coefficient of described heat-conducting polymer dielectric insulation material layer is greater than 1W/mK, thickness is less than 0.5mm, and comprises:

(1) fluoro containing polymers polymer, its fusing point are higher than 150 ℃, and. percent by volume is between 30-60%; And

(2) heat filling intersperse among in the described fluoro containing polymers polymer, and its percent by volume is between 40-70%.

2. the heat radiation substrate of electronic component as claimed in claim 1, the thickness that it is characterized in that described the first metal layer is less than 0.1mm.

3. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described second metal layer thickness is less than 0.2mm.

4. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that the fusing point of described fluoro containing polymers polymer is higher than 220 ℃.

5. the heat radiation substrate of electronic component as claimed in claim 1, the percent by volume that it is characterized in that described heat filling is between 50-65%.

6. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that tension intensity between described heat-conducting polymer dielectric insulation material layer and described first and second electrode layer is greater than 8N/cm.

7. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that wide test substrate surface non-cracking or slight crack generation when song becomes the cylinder of 5mm diameter for 1cm.

8. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that placing 260 ℃ tin stove 5 minutes, the surface do not have bubble and outward appearance unusual.

9. the heat radiation substrate of electronic component as claimed in claim 1, but it is characterized in that proof voltage is greater than 3kV.

10. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described fluoro containing polymers polymer is selected from polyvinylidene fluoride or ethylene-tetrafluoroethylene copolymer.

11. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described fluoro containing polymers polymer is selected from polytetrafluoroethylene, tetrafluoraoethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, perfluor alcoxyl upgrading tetrafluoroethene, poly-(chlorine three-fluorine tetrafluoroethene), vinylidene fluoride-tetrafluoro ethylene polymer, polyvinylidene fluoride, tetrafluoroethene-perfluor dioxole copolymer, vinylidene difluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethene trimer, and tetrafluoroethene-perfluoro methyl vinyl ether adds the monomer trimer that solidifies the territory.

12. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described heat filling is selected from nitride or oxide.

13. the heat radiation substrate of electronic component as claimed in claim 12 is characterized in that described nitride is selected from zirconium nitride, boron nitride, aluminium nitride, silicon nitride.

14. the heat radiation substrate of electronic component as claimed in claim 12 is characterized in that described oxide is selected from aluminium oxide, magnesium oxide, zinc oxide, titanium dioxide.

15. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that the radiation exposure of process≤20Mrad solidifies described heat-conducting polymer dielectric insulation material layer interlinkage.

16. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described electronic component is a light-emitting diode (LED) element.

17. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described the first metal layer comprises copper.

18. the heat radiation substrate of electronic component as claimed in claim 1 is characterized in that described second metal level comprises aluminium.

Images