JP2015207666A - Metal base board, manufacturing method thereof, metal base circuit board, and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal base board which has a metal layer of a particular thickness, and is superior in circuit workability, and which can be adapted for high current use over a long period of time.SOLUTION: A metal base board 100 of the present invention comprises: a metal substrate 101; an insulative resin layer 102 provided on the metal substrate 101; and a metal layer 103 provided on the insulative resin layer 102. In the metal base board 100, the insulative resin layer 102 is formed of an epoxy resin composition; the epoxy resin composition includes a phenoxy resin; and the metal layer 103 is composed of a piece of copper foil having a thickness in a range of 170-230 μm.

Description

  The present invention relates to a metal base substrate, a metal base substrate manufacturing method, a metal base circuit substrate, and an electronic device.

  In various applications, circuit boards on which electronic components such as semiconductor elements are mounted are used. Among them, since it is inexpensive and has excellent thermal stability, a metal base substrate provided with a metal layer formed of a metal foil on an insulating resin layer on a metal substrate is preferably used for applications requiring high current. It has been. For example, an inverter device or a power semiconductor device in which a semiconductor device such as an insulated gate bipolar transistor (IGBT) and a diode, a semiconductor device such as a diode, and an electronic component such as a resistor and a capacitor are mounted on a circuit-processed metal base substrate is known. Yes.

  When such a metal base substrate is used for an application requiring a high current, an attempt has been made to increase the thickness of the metal layer on which a circuit is formed in order to reduce the resistance to a conducting current. However, if the metal layer is made thicker than necessary, there is a problem that not only the thickness of the entire metal base substrate is increased, but also the circuit formability is lowered.

  Patent Document 1 discloses a metal base substrate in which a 0.21 mm copper foil is used as an outer layer circuit of the metal base substrate.

JP 2008-266378 A

  When a 0.21 mm copper foil as described in Patent Document 1 is used, sufficient circuit processability of the metal layer can be ensured. That is, the thickness of the copper foil is preferably used because it can be used for high current applications while ensuring the circuit processability of the copper foil.

Here, in a metal base substrate used for in-vehicle use, it is required to maintain such insulation for a long period of time.
As a result of studies by the present inventor, the metal base substrate described in the cited document 1 has a good insulating property at the start of use, but this insulating property gradually decreases when used for a long time. It has been found that there is room for improvement in this regard.
The reason for this is not clear, but when a relatively thick copper foil of 0.21 mm is used, the difference in behavior during use between the insulating resin layer and the metal foil appears remarkably, so both are easy to peel off. It is thought that it is becoming.

  In view of such circumstances, the present invention provides a metal base substrate that has a metal layer having a specific thickness that is excellent in circuit processability and can be used for a high current application over a long period of time.

According to the present invention,
A metal base substrate comprising a metal substrate, an insulating resin layer provided on the metal substrate, and a metal layer provided on the insulating resin layer,
The insulating resin layer is composed of an epoxy resin composition,
The epoxy resin composition includes a phenoxy resin,
A metal base substrate is provided in which the metal layer is a copper foil having a thickness in the range of 170 μm to 230 μm.

According to this invention, since the thickness of the metal layer is a copper foil in a specific range, sufficient circuit processability can be ensured. Moreover, since an insulating resin layer is comprised from the epoxy resin composition containing a phenoxy resin, it can be equipped with moderate softness | flexibility as an insulating resin layer. As a result, the adhesion between the insulating resin layer and the metal layer is improved, and a metal base substrate that can be used for a high current application over a long period of time can be provided.
By this effect, a metal base substrate that can provide a highly durable electronic device can be obtained.

Moreover, according to the present invention,
A method for producing a metal base substrate comprising a metal substrate, an insulating resin layer provided on the metal substrate, and a metal layer provided on the insulating resin layer,
Applying an epoxy resin composition to the metal layer and heating and drying to obtain a metal foil with resin;
Laminating the metal foil with resin on the metal substrate to obtain a laminate;
And heat and pressure curing the laminate,
The epoxy resin composition includes a phenoxy resin,
The metal layer is a copper foil having a thickness in the range of 170 μm or more and 230 μm or less.

Furthermore, according to the present invention,
There is provided a metal base circuit board obtained by circuit-processing the metal layer of the metal base board described above.

Furthermore, according to the present invention,
A metal base circuit board as described above;
An electronic component provided on the metal base circuit board;
An electronic device is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the metal base board | substrate which can respond to the high current use over a long period of time while having a metal layer of the specific thickness excellent in circuit workability is provided.

It is sectional drawing of the metal base substrate concerning one Embodiment of this invention. It is sectional drawing of the electronic device concerning one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and detailed description thereof is appropriately omitted so as not to overlap. Moreover, the figure is a schematic diagram and does not necessarily match the actual dimensional ratio. In addition, unless otherwise specified, “to” represents the following.

First, the metal base substrate 100 of this embodiment is demonstrated. FIG. 1 is a cross-sectional view of a metal base substrate according to an embodiment of the present invention.
The metal base substrate 100 includes a metal substrate 101, an insulating resin layer 102 provided on the metal substrate 101, and a metal layer 103 provided on the insulating resin layer 102.

<Metal substrate>
The metal substrate 101 has a role of radiating heat accumulated in the metal base substrate 100. The metal substrate 101 is not particularly limited as long as it is a heat-dissipating metal substrate. For example, the metal substrate 101 is an aluminum substrate.

The thickness of the metal substrate 101 can be appropriately set as long as the object of the present invention is not impaired.
The thickness of the metal substrate 101 is, for example, not less than 100 μm and not more than 5000 μm. When the thickness of the metal substrate 101 is not less than the above lower limit value, the heat dissipation can be further improved. Further, when the thickness of the metal substrate 101 is equal to or less than the above upper limit value, workability such as bending of the metal base substrate 100 can be improved.

<Metal layer>
The metal layer 103 is provided on an insulating resin layer 102, which will be described later, and is subjected to circuit processing.
The metal constituting the metal layer 103 is copper.

The thickness of the metal layer 103 is 170 μm or more, preferably 200 μm or more. By using the metal layer 103 having a thickness greater than or equal to this value, even when a circuit is processed and an electronic device for high current use is manufactured, it is possible to suppress a high voltage from being applied to the circuit.
In addition, the thickness of the metal layer 103 is 230 μm or less, preferably 220 μm or less. By using the metal layer 103 having a thickness less than or equal to this numerical value, the metal base substrate 100 as a whole can be thinned. Further, if the metal layer 103 having a thickness equal to or less than this value is used, sufficient circuit processability can be ensured.

  The metal layer 103 may use a copper foil that can be obtained in a plate shape, or may use a copper foil that can be obtained in a roll shape. However, in manufacturing the metal base substrate 100, it is preferable to use a metal material available in a roll shape for the metal layer 103 because manufacturing efficiency can be improved.

<Insulating resin layer>
The insulating resin layer 102 is a layer for bonding the metal layer 103 to the metal substrate 101. The thickness of the insulating resin layer 102 is appropriately set in accordance with the object of the invention, but is preferably 40 μm or more and 300 μm or less, and from the viewpoint of achieving both heat dissipation and insulation in the entire metal base substrate 100, it is 60 μm or more and 200 μm or less. More preferably.
By setting the thickness of the insulating resin layer 102 to be equal to or less than the above upper limit value, heat from the electronic component can be easily transmitted to the metal substrate 101.
Further, by setting the thickness of the insulating resin layer 102 to be equal to or greater than the above lower limit value, it is possible to sufficiently reduce the generation of thermal stress due to the difference in thermal expansion coefficient between the metal substrate 101 and the insulating resin layer 102 with the insulating resin layer 102. . Furthermore, the insulating property of the metal base substrate 100 is improved.

  The insulating resin layer 102 is formed by curing an epoxy resin composition containing an epoxy resin. Although this epoxy resin composition can be suitably selected according to the use to be used, it contains at least an epoxy resin (A) and a phenoxy resin (C), and, if necessary, an inorganic filler (B), An epoxy resin composition containing a curing agent (D) and a coupling agent (E) can be used.

Here, an example of the composition of the epoxy resin composition will be described.
The epoxy resin composition of the present embodiment includes at least an epoxy resin (A) and a phenoxy resin (C), and, if necessary, an inorganic filler (B), a curing agent (D), and a coupling agent (E ).

  Here, as an epoxy resin (A), a naphthalene type epoxy resin (A1) can be included, for example. By including this naphthalene type epoxy resin (A1), the glass transition temperature can be further increased, the generation of voids in the insulating resin layer 102 can be suppressed, the thermal conductivity can be further improved, and the dielectric breakdown voltage can be improved. it can. Here, the naphthalene type epoxy resin refers to one having a naphthalene ring skeleton and having two or more glycidyl groups. The content of the naphthalene type epoxy resin (A1) is preferably 20% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 60% by mass or less, with respect to 100% by mass of the epoxy resin (A). It is.

  As the naphthalene type epoxy resin (A1), for example, any one of the following formulas (5) to (7) can be used. In the formula (6), m and n represent the number of substituents on the naphthalene ring, and each independently represents an integer of 1 to 7. In formula (7), Me represents a methyl group, and l, m, and n are natural numbers of 1 or more. However, l, m, and n are preferably 10 or less.

  In addition, as a compound of Formula (6), it is preferable to use any 1 or more types of the following.

  Moreover, as a naphthalene type epoxy resin (A1), the naphthylene ether type epoxy resin represented by the following formula | equation (8) can also be used.

（上記式（８）において、ｎは１以上２０以下の整数であり、ｌは１以上２以下の整数であり、Ｒ_１はそれぞれ独立に水素原子、ベンジル基、アルキル基または下記式（９）で表される構造であり、Ｒ_２はそれぞれ独立に水素原子またはメチル基である。）

(In the above formula (8), n is an integer of 1 or more and 20 or less, l is an integer of 1 or more and 2 or less, and R ₁ is independently a hydrogen atom, a benzyl group, an alkyl group, or the following formula (9) And each R ₂ is independently a hydrogen atom or a methyl group.)

（上記式（９）において、Ａｒはそれぞれ独立にフェニレン基またはナフチレン基であり、Ｒ_２はそれぞれ独立に水素原子またはメチル基であり、ｍは１または２の整数である。）

(In the above formula (9), Ar is each independently a phenylene group or a naphthylene group, R ₂ is each independently a hydrogen atom or a methyl group, and m is an integer of 1 or 2.)

  Examples of the naphthylene ether type epoxy resin represented by the above formula (8) include those represented by the following formula (10).

（上記式（１０）において、ｎは１以上２０以下の整数であり、好ましくは１以上１０以下の整数であり、より好ましくは１以上３以下の整数である。Ｒはそれぞれ独立に水素原子または下記式（１１）で表される構造であり、好ましくは水素原子である。）

(In the above formula (10), n is an integer of 1 or more and 20 or less, preferably an integer of 1 or more and 10 or less, more preferably an integer of 1 or more and 3 or less. R is independently a hydrogen atom or (It is a structure represented by the following formula (11), preferably a hydrogen atom.)

（上記式（１１）において、ｍは１または２の整数である。）

(In the above formula (11), m is an integer of 1 or 2.)

  Examples of the naphthylene ether type epoxy resin represented by the above formula (10) include those represented by the following formulas (12) to (16).

  Moreover, as an epoxy resin (A), epoxy resins other than a naphthalene type epoxy resin (A1) can also be used. The types of epoxy resins that can be used include, for example, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol E type epoxy resins, bisphenol M type epoxy resins, bisphenol P type epoxy resins, and bisphenols. Bisphenol type epoxy resins such as Z type epoxy resins; Novolak type epoxy resins such as phenol novolak type epoxy resins, cresol novolak type epoxy resins, tetraphenol group ethane type novolak type epoxy resins; An epoxy resin such as an arylalkylene type epoxy resin such as a type epoxy resin.

  Although content of the epoxy resin (A) contained in an epoxy resin composition is suitably adjusted according to the objective, 1 mass% or more and 23 mass% with respect to 100 mass% of total solids of an epoxy resin composition. The following is preferable, and 2 mass% or more and 15 mass% or less are more preferable. When the content of the epoxy resin (A) is not less than the above lower limit value, the handleability is improved and the insulating resin layer 102 can be easily formed. When the content of the epoxy resin (A) is not more than the above upper limit value, the strength and flame retardancy of the insulating resin layer 102 are further improved, and the thermal conductivity of the insulating resin layer 102 is further improved.

In the epoxy resin composition of this embodiment, an inorganic filler (B) is used. For example, silicates such as talc, calcined clay, unfired clay, mica and glass; oxides such as titanium oxide, alumina, boehmite, silica and fused silica; carbonates such as calcium carbonate, magnesium carbonate and hydrotalcite; Hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite; zinc borate, barium metaborate, aluminum borate, calcium borate, boron An inorganic filler such as borate such as sodium oxide; nitride such as aluminum nitride, boron nitride, silicon nitride, and carbon nitride; titanate such as strontium titanate and barium titanate can be used.
Among these, boron nitride and alumina are preferably used because of their high thermal conductivity, and alumina is particularly preferable in consideration of production costs.

When alumina is used as the inorganic filler (B), it is a mixed system of three components (large particle size, medium particle size, small particle size) having different average particle sizes, the large particle size component is spherical, and the medium particle size component The small particle size component is preferably polyhedral.
More specifically, alumina belongs to the first particle size range in which the average particle size is 5.0 μm or more and 50 μm or less, preferably 5.0 μm or more and 25 μm or less, and the circularity is 0.80 or more and 1.0 or less. And preferably having a large particle size of alumina of 0.85 or more and 0.95 or less and a second particle size range in which the average particle size is 1.0 μm or more and less than 5.0 μm, and the circularity is 0.50 or more and 0 .90 or less, preferably 0.70 or more and 0.80 or less of the medium particle size alumina, the average particle size belongs to the third particle size range of 0.1 μm or more and less than 1.0 μm, and the circularity is 0.00. It is preferable to be a mixture of 50 to 0.90, preferably 0.70 to 0.80 small particle size alumina.
Here, the particle size can be measured by dispersing alumina in water for 1 minute using a laser diffraction / scattering particle size distribution analyzer SALD-7000.
The circularity can be measured by using a flow type particle image analyzer FPIA-3000 manufactured by Sysmex and employing the sample preparation method and the diffraction method described in Examples.

As a result, the medium particle size component is filled in the gap between the large particle size components, and the small particle size component is filled in the gap between the medium particle size components, so that the alumina filling property is improved and the contact area between the alumina particles is increased. Can be made larger. As a result, the thermal conductivity of the insulating resin layer 102 can be further improved. Furthermore, the solder heat resistance, flex resistance, and insulation of the insulating resin layer 102 can be further improved.
Further, by using such alumina, the adhesion between the insulating resin layer 102 and the metal substrate 101 can be further improved.
Due to these synergistic effects, the insulation reliability of the metal base substrate 100 can be further enhanced.

  The content of the inorganic filler (B) contained in the epoxy resin composition is, for example, 75% by mass to 95% by mass with respect to 100% by mass of the total solid content of the epoxy resin composition, and more preferably. It is 80 mass% or more and 90 mass% or less. By making the content of the inorganic filler (B) high as in the above numerical range, the contact area between the particles of the inorganic filler increases. More specifically, regarding the content of the inorganic filler (B), alumina can be used as the inorganic filler (B) and can be included in the epoxy resin composition within the above numerical range. As a result, the thermal conductivity of the insulating resin layer 102 can be improved, and the heat dissipation of the electronic device 11 (see FIG. 2) can be improved. Therefore, the heat of the electronic component can be sufficiently transferred to the outside. Thereby, the highly durable electronic device 11 can be obtained.

  Further, when alumina is used as the inorganic filler (B), the content of alumina belonging to the first particle size range is preferably 65% by mass or more and 85% by mass or less with respect to 100% by mass as a whole. The content of alumina belonging to the diameter range is preferably 10% by mass or more and 20% by mass or less, and the content of alumina belonging to the third particle size range is preferably 5% by mass or more and 18% by mass or less.

In the present embodiment, the epoxy resin composition includes a phenoxy resin (C). By including the phenoxy resin (C), the elastic modulus of the insulating resin layer 102 can be reduced, and in this case, the stress relaxation force of the metal base substrate 100 can be improved. As a result, even when a relatively thick copper foil is used, peeling between the metal layer 103 and the insulating resin layer 102 can be suppressed.
Furthermore, when the electronic device 11 is manufactured, defects such as cracks may occur at or near the solder joint where the electronic component and the metal base substrate 100 are joined, even under a rapid heating / cooling environment. Will be suppressed. Thus, the heat cycle characteristics of the metal base substrate 100 can be further improved.
In addition, since the bending resistance of the insulating resin layer 102 can be improved by including the phenoxy resin (C), the handling property of the insulating resin layer 102 due to high filling with the inorganic filler (B) is suppressed. Can do.
Moreover, when phenoxy resin (C) is included, the fluidity | liquidity at the time of a press reduces by viscosity increase and it can suppress that a void etc. generate | occur | produce. In addition, the adhesion between the insulating resin layer 102 and the metal substrate 101 can be improved. Due to these synergistic effects, the insulation reliability of the metal base substrate 100 can be further enhanced.

  Examples of the phenoxy resin (C) include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a naphthalene skeleton, a phenoxy resin having an anthracene skeleton, and a phenoxy resin having a biphenyl skeleton. A phenoxy resin having a structure having a plurality of these skeletons can also be used.

  Among these, it is preferable to use bisphenol A type or bisphenol F type phenoxy resin. A phenoxy resin having both a bisphenol A skeleton and a bisphenol F skeleton may be used.

The weight average molecular weight of the phenoxy resin (C) is not particularly limited, but is preferably 4.0 × 10 ⁴ or more and 8.0 × 10 ⁴ or less.
In addition, the weight average molecular weight of phenoxy resin (C) is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

The content of the phenoxy resin (C) is, for example, preferably 1% by mass to 15% by mass, more preferably 2% by mass to 10% by mass, with respect to 100% by mass of the total solid content of the epoxy resin composition. is there.
By doing in this way, what has moderate softness | flexibility as the insulating resin layer 102 can be obtained.

Examples of the curing agent (D) (curing catalyst) include organic metals such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), and trisacetylacetonate cobalt (III). Salt: Dicyandiamide, diethylenetriamine, triethylenetetramine, metaxylylenediamine, diaminodiphenylmethane, diaminodiethyldiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, isophoronediamine, norbornenediamine, triethylamine, tributylamine, diazabicyclo [2,2,2] Amine-based curing agents such as octane; 2-phenyl-imidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethyl-4 Imidazole-based curing agents such as ethylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole, 2-phenyl-4,5-dihydroxyimidazole; triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenyl Organophosphorus compounds such as borate, triphenylphosphine / triphenylborane, 1,2-bis- (diphenylphosphino) ethane; phenolic compounds such as phenol, bisphenol A, nonylphenol; acetic acid, benzoic acid, salicylic acid, paratoluenesulfonic acid Organic acids, etc., or a mixture thereof. As a hardening | curing agent (D), 1 type including these derivatives can also be used independently, and 2 or more types including these derivatives can also be used together.
Among these, an amine-based curing agent and an imidazole-based curing agent are preferable in that a cured product having excellent adhesiveness, reacting at a relatively low temperature, and excellent heat resistance can be obtained.

  Although content of a hardening | curing agent (D) is not specifically limited, For example, they are 0.05 mass% or more and 3.0 mass% or less with respect to 100 mass% of total solid content of an epoxy resin composition.

  Furthermore, the epoxy resin composition may include a coupling agent (E). The coupling agent (E) can improve the wettability of the interface between the epoxy resin (A) and the inorganic filler (B).

As the coupling agent (E), any of those usually used can be used. Specifically, an epoxy silane coupling agent, a cationic silane coupling agent, an aminosilane coupling agent, a titanate coupling agent, and a silicone oil type. It is preferable to use one or more coupling agents selected from coupling agents.
The amount of the coupling agent (E) added depends on the specific surface area of the inorganic filler (B) and is not particularly limited, but is 0.05 parts by mass or more and 3 parts by mass with respect to 100 parts by mass of the inorganic filler (B). The following is preferable, and 0.1 to 2 parts by mass is particularly preferable.

  The epoxy resin composition can contain an antioxidant, a leveling agent and the like as long as the effects of the present invention are not impaired.

Next, the physical properties of the epoxy resin composition will be described.
The epoxy resin composition of the present embodiment preferably has the following viscosity behavior. When the epoxy resin composition is heated from 60 ° C. to a molten state at a rate of temperature increase of 3 ° C./min and a frequency of 1 Hz using a dynamic viscoelasticity measuring device, the melt viscosity initially decreases and the minimum melt viscosity And the minimum melt viscosity is in the range of 1 × 10 ³ Pa · s to 1 × 10 ⁵ Pa · s.
When the minimum melt viscosity is not less than the above lower limit value, the epoxy resin (A) and the inorganic filler (B) are separated, and only the epoxy resin (A) can be prevented from flowing, and a more homogeneous insulating resin Layer 102 can be obtained.
Further, when the minimum melt viscosity is not more than the above upper limit value, the wettability of the epoxy resin composition to the metal substrate 101 can be improved, and the adhesion between the insulating resin layer 102 and the metal substrate 101 can be further improved.
These synergistic effects can further improve the heat dissipation and dielectric breakdown voltage of the metal base substrate 100. Furthermore, the heat cycle characteristics of the metal base substrate 100 can be further improved.

The epoxy resin composition of the present embodiment preferably has a temperature at which the minimum melt viscosity is reached in the range of 60 ° C. or higher and 100 ° C. or lower.
Moreover, the epoxy resin composition of the present embodiment preferably has a flow rate of 15% or more and less than 60%. The flow rate can be measured by the following procedure. First, 5-7 sheets of metal foil having a resin layer formed of the epoxy resin composition of the present embodiment are cut into a predetermined size (50 mm × 50 mm), and the weight is measured. Next, after pressing for 5 minutes between hot plates maintained at an internal temperature of 175 ° C. and cooling, the resin that has flowed out is carefully dropped and the weight is measured again. The flow rate can be obtained by the following formula (I).
Flow rate (%) = (weight before measurement−weight after measurement) / (weight before measurement−weight of metal foil) (I)
With such a viscosity behavior, when the epoxy resin composition is heated and cured to form the insulating resin layer 102, air can be prevented from entering the epoxy resin composition, and in the epoxy resin composition. The dissolved gas can be discharged to the outside sufficiently. As a result, generation of bubbles in the insulating resin layer 102 can be suppressed, and heat can be reliably transmitted from the insulating resin layer 102 to the metal substrate 101. Moreover, the insulation reliability of the metal base substrate 100 can be improved by suppressing the generation of bubbles. In addition, the adhesion between the insulating resin layer 102 and the metal substrate 101 can be improved.
These synergistic effects can further improve the heat dissipation of the metal base substrate 100, and as a result, the heat cycle characteristics of the metal base substrate 100 can be further improved.

  In order to realize an epoxy resin composition having such a viscosity behavior, for example, the type and amount of the epoxy resin (A) described above, the type and amount of the inorganic filler (B), and the type of phenoxy resin (C) The amount may be adjusted as appropriate. In this embodiment, since the phenoxy resin (C) having good fluidity is used, the above-described viscosity characteristics are easily obtained.

Next, physical properties of the insulating resin layer 102 will be described.
The insulating resin layer 102 has high thermal conductivity. Specifically, the thermal conductivity in the thickness direction of the insulating resin layer 102 measured by a laser flash method is preferably 2.0 W / (m · K) or more, and 3.0 W / (m · K). More preferably.
Thereby, the heat from the electronic component can be easily transmitted to the metal substrate 101 through the insulating resin layer 102.

In addition, the insulating resin layer 102 has increased rigidity and can reduce warping of the insulating resin layer 102. As a result, positional displacement of the electronic component with respect to the metal base substrate 100 can be suppressed, and the gap between the electronic component and the metal base substrate 100 can be suppressed. From the viewpoint of further improving the connection reliability, the glass transition temperature is preferably 100 ° C. or higher and 150 ° C. or lower, more preferably 110 ° C. or higher and 140 ° C. or lower. The glass transition temperature of the insulating resin layer 102 can be measured as follows based on JIS C 6481.
Using a dynamic viscoelasticity measuring device (DMA Instruments' DMA / 983) under a nitrogen atmosphere (200 ml / min), a tensile load was applied, and a frequency of 1 Hz and a temperature of −50 ° C. to 300 ° C. The range is measured at a temperature rising rate of 5 ° C./min, and the glass transition temperature Tg is obtained from the peak position of tan δ.

Further, the elastic modulus (storage elastic modulus) E ′ of 25 ° C. of the insulating resin layer 102 increases the rigidity and can reduce the warp of the insulating resin layer 102. As a result, it is possible to suppress the displacement of the electronic component with respect to the circuit board, From the viewpoint of further enhancing the connection reliability between the electronic component and the circuit board, it is preferably 30 GPa or more and 70 GPa or less.
In addition, the said storage elastic modulus is measured with the dynamic viscoelasticity measuring apparatus.
The storage elastic modulus E ′ is a storage elastic modulus of 25 ° C. when a tensile load is applied to the insulating resin layer 102 and measured at −50 ° C. to 300 ° C. at a frequency of 1 Hz and a heating rate of 5 to 10 ° C./min. Value.

Moreover, the dielectric breakdown voltage of the insulating resin layer 102 is preferably 50 kV / mm or more, and more preferably 54 kV / mm or more.
If the dielectric breakdown voltage is equal to or higher than the above value, sufficient insulation can be ensured even when the metal base substrate 100 is used for higher current applications.

<Production method of metal base substrate>
The metal base substrate 100 as described above can be manufactured, for example, as follows.
That is, the metal base substrate 100 of the present embodiment is obtained by first producing a carrier material with a resin layer, laminating the carrier material with a resin layer on the metal substrate 101, and curing the obtained laminate by heating and pressing. It is done.

First, a resin layer is formed on a carrier material to obtain a carrier material with a resin layer.
The carrier material is, for example, a resin film such as polyethylene terephthalate (PET); a metal foil such as a copper foil. The thickness of the carrier material is, for example, 10 to 500 μm.

  Next, the carrier material with a resin layer is laminated on the metal substrate 101 so that the surface on the resin layer side of the carrier material with the resin layer is in contact with the surface of the metal substrate 101. Thereafter, the resin layer is brought into a B stage state by pressurization and heat curing using a press or the like.

Next, the carrier material is removed from the resin layer in the B-stage state, and the metal layer 103 is formed on the surface of the exposed resin layer.
In addition, when using copper foil as a carrier material, this carrier material can be used as the metal layer 103 as it is. That is, in this case, a copper foil having a thickness of 170 μm or more and 230 μm or less is used as the carrier material, and a resin-coated metal foil that once falls within the above numerical range as the thickness of the copper foil is obtained. Then, the target laminated body is obtained by laminating the metal foil with resin on the metal substrate 101.
Note that another layer such as an adhesive layer may be interposed between the resin layer and the metal substrate 101 or between the resin layer and the metal layer 103.
Then, the metal base substrate 100 is obtained by post-curing the laminate.

Moreover, when using copper foil as a carrier material and making the said metal foil into the metal layer 103 as it is, the metal layer 103 can be made into the copper foil extruded from the roll.
By doing in this way, improvement in production efficiency can be aimed at.

<Metal base circuit board>
The obtained metal base substrate 100 can be processed by etching the metal layer 103 into a predetermined pattern, and a metal base circuit substrate can be obtained.
Further, a solder resist 10 (see FIG. 2) may be formed on the outermost layer, and the connection electrode portion may be exposed so that electronic parts can be mounted by exposure and development.

<Electronic device>
The electronic device 11 can be obtained by providing electronic components on the metal base circuit board of the present embodiment.
In the present embodiment, the electronic device 11 is a semiconductor device, such as a power semiconductor device, LED lighting, or an inverter device.
Here, the inverter device electrically generates AC power from DC power (has a reverse conversion function). A power semiconductor device is characterized by higher withstand voltage, higher current, higher speed and higher frequency than ordinary semiconductor elements, and is generally called a power device. , Power MOSFET, insulated gate bipolar transistor (IGBT), thyristor, gate turn-off thyristor (GTO), triac and the like.
Electronic components are semiconductor elements such as insulated gate bipolar transistors, diodes, and IC chips, and various heating elements such as resistors and capacitors. The metal base substrate 100 functions as a heat spreader.

Here, an example of the electronic device 11 will be described with reference to FIG.
In the electronic device 11 of this embodiment, the IC chip 2 is mounted on the metal layer 103a of the metal base circuit board via the adhesive layer 3. The IC chip 2 is electrically connected to the metal layer 103b through the bonding wire 7.
Further, the IC chip 2, the bonding wire 7, and the metal layers 103 a and 103 b are sealed with a sealing material 6.

  In the electronic device 11, the chip capacitor 8 and the chip resistor 9 are mounted on the metal layer 103. Conventionally known chip capacitors 8 and chip resistors 9 can be used.

  Further, the metal substrate 101 of the electronic device 11 is connected to the heat radiating fins 5 through the heat conductive grease 4. That is, the heat generated by the IC chip 2 is conducted to the heat radiating fins 5 through the adhesive layer 3, the metal layer 103 a, the insulating resin layer 102, the metal substrate 101, and the heat conductive grease 4 to remove heat. Can do.

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these. In the examples, unless otherwise specified, parts represent parts by mass. Each thickness is expressed by an average film pressure.

[Preparation of Epoxy Resin Composition A]
Phenoxy resin having bisphenol F skeleton and bisphenol A skeleton (Mitsubishi Chemical Co., Ltd., 4275, weight average molecular weight 6.0 × 10 ⁴ , ratio of bisphenol F skeleton to bisphenol A skeleton = 75: 25) 3.9 parts by mass, bisphenol F-type epoxy resin (DIC, 830S, epoxy equivalent 170) 3.0 parts by mass, naphthalene-type epoxy resin (DIC, HP-6000, epoxy equivalent 250: in chemical formula (10), each R is a hydrogen atom A mixture of a component where n = 1 and a component where n = 2), 3.0 parts by weight of dicyandiamide (manufactured by Degussa), γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone) Manufactured by KBM-403) 1.3 parts by mass, spherical alumina (average particle size 22 μm, circularity: 0.91, Nippon Steel & Sumitomo Metal) Terials, AX-25) 67.3 parts by mass, polyhedral alumina (average particle diameter 4 μm, circularity: 0.75, Nippon Light Metal Co., Ltd., LS-210) 13.2 parts by mass, polyhedral alumina (average A particle size of 0.7 μm, circularity: 0.71, 8.0 parts by weight of Nippon Light Metal Co., Ltd., LS-250) was dissolved and mixed in cyclohexanone, and stirred using a high-speed stirrer. A mass% varnish-like epoxy resin composition A was obtained.
The circularity of alumina was measured using a flow type particle image analyzer “FPIA-3000” manufactured by Sysmex. A measurement sample was prepared by adding an appropriate amount of a surfactant to 50 to 100 ml of distilled water, adding 10 to 20 mg of alumina particles thereto, and then dispersing the mixture with an ultrasonic disperser for 1 minute. For the circularity, the flow type particle image analyzer “FPIA-3000” analyzes the circumference of one particle projection image and the circumference of a circle corresponding to the area of the particle projection image, and obtains the circularity by the following equation: The average value per 20,000 is automatically calculated. Moreover, it measures on the same conditions also about the epoxy resin composition BE shown below.
Circularity = (perimeter of circle corresponding to area of particle projection image) / (perimeter of particle projection image)

[Preparation of Epoxy Resin Composition B]
Phenoxy resin having bisphenol F skeleton and bisphenol A skeleton (Mitsubishi Chemical Co., Ltd., 4275, weight average molecular weight 6.0 × 10 ⁴ , ratio of bisphenol F skeleton to bisphenol A skeleton = 75: 25) 3.9 parts by mass, bisphenol F-type epoxy resin (DIC, 830S, epoxy equivalent 170) 3.0 parts by mass, naphthalene-type epoxy resin (DIC, HP-6000, epoxy equivalent 250: in chemical formula (10), each R is a hydrogen atom A mixture of a component where n = 1 and a component where n = 2), 3.0 parts by weight of dicyandiamide (manufactured by Degussa), γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone) Manufactured by KBM-403) 1.3 parts by mass, spherical alumina (average particle size 16 μm, circularity: 0.93, Showa Denko) CB-P15) 67.3 parts by mass, polyhedral alumina (average particle size 4 μm, circularity: 0.75, Nippon Light Metal Co., Ltd., LS-210) 13.2 parts by mass, polyhedral alumina (average particle size 0) .7 μm, circularity: 0.71, Nippon Light Metal Co., Ltd., LS-250) 8.0 parts by mass was dissolved and mixed in cyclohexanone, and stirred using a high-speed stirrer. A varnish-like epoxy resin composition B was obtained.

[Preparation of Epoxy Resin Composition C]
Phenoxy resin having bisphenol F skeleton and bisphenol A skeleton (Mitsubishi Chemical Co., Ltd., 4275, weight average molecular weight 6.0 × 10 ⁴ , ratio of bisphenol F skeleton to bisphenol A skeleton = 75: 25) 8.8 parts by mass, bisphenol 6.6 parts by mass of an F-type epoxy resin (manufactured by DIC, 830S, epoxy equivalent 170), naphthalene-type epoxy resin (manufactured by DIC, HP-6000, epoxy equivalent 250): In chemical formula (10), each R is a hydrogen atom 6.6 parts by mass of a mixture of a component where n = 1 and a component where n = 2), 0.7 part by mass of dicyandiamide (Degussa), γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone) Manufactured by KBM-403) 1.3 parts by mass, spherical alumina (average particle size 22 μm, circularity: 0.91, Nippon Steel & Sumitomo Metal) Terials Inc., AX-25) 57.8 parts by mass, polyhedral alumina (average particle size 4 μm, circularity: 0.75, Nippon Light Metal Co., Ltd., LS-210) 11.4 parts by mass, polyhedral alumina (average 6.8 parts by mass of a particle size of 0.7 μm, circularity: 0.71, Nippon Light Metal Co., Ltd. (LS-250) was dissolved and mixed in cyclohexanone, and stirred using a high-speed agitator. A mass% varnish-like epoxy resin composition C was obtained.

[Preparation of Epoxy Resin Composition D]
Bisphenol F type epoxy resin (DIC, 830S, epoxy equivalent 170) 4.9 parts by mass, naphthalene type epoxy resin (DIC, HP-6000, epoxy equivalent 250: in chemical formula (10), R is all hydrogen 5.0 parts by mass of a mixture of a component with n = 1 and a component with n = 2), 0.5 part by mass of dicyandiamide (Degussa), γ-glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone) Company, KBM-403) 1.3 parts by mass, spherical alumina (average particle size 22 μm, circularity: 0.91, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., AX-25) 67.1 parts by mass, polyhedral alumina (average Particle diameter 4 μm, circularity: 0.75, Nippon Light Metal Co., Ltd., LS-210) 13.2 parts by mass, polyhedral alumina (average particle diameter 0.7 μm, circularity: 0.71 LS-250), 8.0 parts by mass, manufactured by Nippon Light Metal Co., Ltd., is dissolved and mixed in cyclohexanone and stirred using a high-speed stirrer to obtain 86% by mass of a varnish-like epoxy resin composition D based on the solid content. Obtained.

[Preparation of Epoxy Resin Composition E]
3.0 parts by mass of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, # 828, epoxy equivalents 184 to 194), 3.0 parts by mass of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, # 1004, epoxy equivalents 875 to 975) Parts, bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, # 1009, epoxy equivalent 2400-3300) 3.9 parts by mass, dicyandiamide (Degussa) 0.2 parts by mass, γ-glycidoxypropyltrimethoxysilane ( Shin-Etsu Silicone Co., Ltd., KBM-403) 1.3 parts by mass, spherical alumina (average particle size 22 μm, circularity: 0.91, manufactured by Nippon Steel & Sumikin Materials Co., Ltd., AX-25) 67.4 parts by mass, polyhedral alumina (Average particle diameter 4 μm, circularity: 0.75, Nippon Light Metal Co., Ltd., LS-210) 13.2 parts by mass, polyhedral alumina (average A child diameter 0.7 μm, circularity: 0.71, 8.0 parts by weight made by Nippon Light Metal Co., Ltd., LS-250) was dissolved and mixed in cyclohexanone, and stirred using a high-speed stirrer. A varnish-like epoxy resin composition E of mass% was obtained.

  About the epoxy resin composition AE obtained as mentioned above, it analyzed about the following characteristics. The results are as shown in Table 1.

(1) Viscosity characteristics Using a rheometer MCR301 manufactured by Anton Paar Japan, the temperature was increased from 60 ° C to 160 ° C at a rate of temperature increase of 3 ° C / min and a frequency of 1 Hz. From the obtained viscosity profile, the minimum melt viscosity and the temperature at which the minimum melt viscosity was reached were determined.

(2) Flow rate After the obtained metal foil with resin is cut to 50 mm x 50 mm, 5 sheets are laminated and sandwiched between hot plates maintained at an internal temperature of 175 ° C, and the pressure is 50 kg / cm ² for 5 minutes. It cooled after pressing. Thereafter, the resin that flowed out was cut off, and the flow rate was calculated according to the above-described calculation formula (I).

Example 1
[Production of metal base substrate]
As the metal foil, a 210 μm thick copper foil (JTC-210, manufactured by JX Nippon Mining & Metals Co., Ltd.) was used, and a varnished epoxy resin composition A was applied to the roughened surface of the copper foil with a comma coater. Heat-dried at 3 ° C. for 3 minutes and 150 ° C. for 3 minutes to obtain a resin-coated copper foil having a resin thickness of 80 μm.
The resin-coated copper foil and a 1 mm thick aluminum plate (Nippon Light Metal Co., Ltd., A5052P) are bonded together, and pressed with a vacuum press at a press pressure of 100 kg / cm ² at 80 ° C. for 30 minutes and 180 ° C. for 60 minutes. A metal base substrate (the thickness of the insulating resin layer 102: 80 μm) was obtained.

(Example 2)
A metal base substrate was obtained in the same manner as in Example 1 except that the epoxy resin composition A was changed to the epoxy resin composition B.

(Example 3)
A metal base substrate was obtained in the same manner as in Example 1 except that the epoxy resin composition A was changed to the epoxy resin composition C.

Example 4
The metal base substrate was the same as in Example 1 except that a copper foil with a thickness of 175 μm was used instead of a copper foil with a thickness of 210 μm (GTS-STD, manufactured by Furukawa Electric Co., Ltd.). Got.

(Comparative Example 1)
A metal base was used in the same manner as in Example 1 except that a copper foil having a thickness of 210 μm was not used when a copper foil with resin was used, and a copper plate having a thickness of 500 μm (manufactured by JX Nippon Mining & Metals, Tough Pitch C110) was used. A substrate was obtained.

(Comparative Example 2)
A metal base substrate was obtained in the same manner as in Example 1 except that the epoxy resin composition A was changed to the epoxy resin composition D.

(Comparative Example 3)
A metal base substrate was obtained in the same manner as in Example 1 except that the epoxy resin composition A was changed to the epoxy resin composition E.

  The following evaluation was performed about the metal base substrate obtained in Examples 1-4 and Comparative Examples 1-3. The evaluation results are as shown in Table 2.

(1) Circuit processability A dry film type etching resist is laminated on the metal layer surface of a metal base substrate 450 mm × 350 mm, exposed and developed, and then a predetermined metal layer by a subtractive method using a ferric chloride-based copper etchant. Was processed to prepare a predetermined circuit. As an evaluation of the circuit workability, the upper side width of the manufactured circuit is within a predetermined width ± 10% and the shape of the circuit cross section satisfies the upper side width / bottom side width = 0.7 to 1.0. Those not satisfying the above numerical range were evaluated as x.

(2) Dielectric breakdown voltage After the metal base substrate was cut to 100 mm × 100 mm with a grinder saw, the copper foil was removed by etching to prepare a sample. Using a withstand voltage tester (MODEL7473, manufactured by EXTECH Electronics), the electrode was brought into contact with the insulating resin layer and the aluminum plate, and an AC voltage was applied to both electrodes so that the voltage increased at a rate of 0.5 kV / sec. Applied. The voltage at which the insulating resin layer of the metal base substrate was broken was divided by the thickness (80 μm) of the insulating resin layer to obtain a dielectric breakdown voltage (kW / mm) per unit thickness (mm).

(3) Thermal conductivity The copper foil and the aluminum plate were peeled from the metal base circuit board to obtain an insulating resin layer. And the heat conductivity of the thickness direction of the insulating resin layer was measured. Specifically, from the thermal diffusion coefficient (α) measured by the laser flash method (half-time method), the specific heat (Cp) measured by the DSC method, and the density (ρ) measured according to JIS-K-6911. The thermal conductivity was calculated using the following formula. The unit of thermal conductivity is W / m · K.
Thermal conductivity [W / m · K] = α [mm ² / s] × Cp [J / kg · K] × ρ [g / cm ³ ]

(4) Tg (glass transition temperature)
Based on JIS C 6481, it measured as follows.
The copper foil and the aluminum plate were peeled from the metal base substrate to obtain an insulating resin layer. A tensile load was applied under a nitrogen atmosphere (200 ml / min) using a dynamic viscoelasticity measuring apparatus (DMA / 983 manufactured by TA Instruments Inc.), and a frequency of 1 Hz, −50 ° C. to 300 ° C. The glass transition temperature Tg was obtained from the peak position of tan δ.

(5) Storage elastic modulus (E ')
The copper foil and the aluminum plate were peeled from the metal base substrate to obtain an insulating resin layer. Then, the insulating resin layer was cut to obtain an 8 × 20 mm test piece. Using a dynamic viscoelasticity measuring device, measurement was performed in a temperature range of −50 ° C. to 300 ° C. with a tensile mode, a frequency of 1 Hz, and a temperature rising rate of 5 ° C./min. And the storage elastic modulus of 25 degreeC was obtained.

(6) Peel strength After cutting the metal base substrate to 100 mm x 25 mm with a grinder saw, a sample was prepared by leaving only 100 mm x 10 mm of copper foil at the center, and the peel between the copper foil and the insulating resin layer at 23 ° C The strength was measured. The peel strength measurement was performed according to JIS C 6481.

(7) Insulation during bending After cutting the metal base substrate to 100 mm x 25 mm with a grinder saw, a sample is prepared by leaving only 100 mm x 10 mm of copper foil in the center by etching, with the copper foil side facing outside or inside. The center was pressed against a round bar of R = 10 and bent 90 degrees. The insulation resistance was measured by applying a terminal of an insulation resistance meter to the aluminum end opposite to the end of the copper foil, that is, the back surface 100 mm away from the terminal on the copper foil side. At this time, the evaluation was evaluated as “O” when the insulation resistance value was 1 × 10 ⁹ Ω or more and “X” when the insulation resistance value was less than 1 × 10 ⁹ Ω.

(8) Heat cycle test An insulating sheet and a lead frame made of Cu were arranged on the metal base substrates obtained in Examples 1 to 4 and Comparative Examples 1 to 3. As the insulating sheet, Fuko TM sheet HF manufactured by Furukawa Electric was used. Thereafter, the die pad portion of the lead frame and the electronic component were joined via solder (material Sn-3.0Ag-0.5Cu).
As described above, three electronic devices were prepared and a heat cycle test was performed. The heat cycle test was performed 3000 times with one cycle of −40 ° C. for 5 minutes to + 125 ° C. for 5 minutes. After the heat cycle test, the crack rate of the solder portion was observed with a microscope.
A case in which even one of the three electronic devices has a crack rate of 100% is regarded as defective (x), and all three electronic devices have a crack rate of less than 100% as good (O). Judged.
Here, the crack rate of the solder portion refers to the crack progress rate of the solder portion of the component joint portion. The ratio is 100% when the crack progresses and the connection with the substrate is completely disconnected.

As shown in Table 2, the metal base substrates obtained in Examples 1 to 4 were sufficiently excellent in circuit workability and excellent in heat cycle properties. Therefore, it is expected that the metal base substrate having a desired copper foil thickness can be used for a long time.
Moreover, the metal base substrate obtained by Examples 1-4 is excellent in the insulation at the time of a bending. This not only indicates that it can be used as a bent metal base substrate, but also shows moderate flexibility as an insulating resin layer and supports high adhesion to the metal layer. .
On the other hand, the metal base substrate obtained in Comparative Example 1 was inferior in circuit workability as compared with the metal base substrates obtained in Examples 1 to 4. Therefore, it is suggested that the practicality as a metal base substrate is lacking. Compared with the metal base substrate obtained by Examples 1-4, the metal base substrate obtained by Comparative Examples 2 and 3 was inferior in heat cycle property and insulation at the time of bending. This is presumably because the epoxy resin composition used for the insulating resin layer does not contain a phenoxy resin. For this reason, these metal base substrates also have problems when they are used for a long period of high current.

2 IC chip 3 Adhesive layer 4 Thermal conduction grease 5 Radiation fin 6 Sealing material 7 Bonding wire 8 Chip capacitor 9 Chip resistor 10 Solder resist 11 Electronic device 100 Metal base substrate 101 Metal substrate 102 Insulating resin layer 103 Metal layer 103a Metal layer 103b Metal layer

Claims (12)

A metal base substrate comprising a metal substrate, an insulating resin layer provided on the metal substrate, and a metal layer provided on the insulating resin layer,
The insulating resin layer is composed of an epoxy resin composition,
The epoxy resin composition includes a phenoxy resin,
The metal layer is a metal base substrate, wherein the metal layer is a copper foil having a thickness in a range of 170 μm to 230 μm. The metal base substrate according to claim 1,
Content of the phenoxy resin contained in the said epoxy resin composition is a metal base board which is 1 to 15 mass% with respect to 100 mass% of total solids of the said epoxy resin composition. The metal base substrate according to claim 1 or 2,
The said epoxy resin composition is a metal base board | substrate containing a naphthalene type epoxy resin. The metal base substrate according to any one of claims 1 to 3,
The epoxy resin composition further includes alumina. The metal base substrate according to claim 4,
The metal base substrate whose content of the said alumina is 75 mass% or more and 95 mass% or less with respect to 100 mass% of total solids of the said epoxy resin composition. The metal base substrate according to any one of claims 1 to 5,
The metal base substrate, wherein the insulating resin layer has a thickness of 40 μm or more and 300 μm or less. The metal base substrate according to any one of claims 1 to 6,
The metal base substrate whose glass transition temperature of the said insulating resin layer is 100 degreeC or more and 150 degrees C or less. The metal base substrate according to any one of claims 1 to 7,
The metal base substrate whose storage elastic modulus in 25 degreeC of the said insulating resin layer is 30 GPa or more and 70 GPa or less. A metal base substrate comprising: a metal substrate; an insulating resin layer provided on the metal substrate; and a metal layer provided on the insulating resin layer,
Applying an epoxy resin composition to the metal layer and heating and drying to obtain a metal foil with resin;
Laminating the metal foil with resin on the metal substrate to obtain a laminate;
And heat and pressure curing the laminate,
The epoxy resin composition includes a phenoxy resin,
The metal layer is a method for producing a metal base substrate, wherein the metal layer is a copper foil having a thickness in a range of 170 μm to 230 μm. A method of manufacturing a metal base substrate according to claim 9,
The said metal layer is a manufacturing method of the metal base board | substrate which is the copper foil extruded from the roll.   A metal base circuit board obtained by processing a circuit of the metal layer of the metal base board according to claim 1. A metal-based circuit board according to claim 11;
Electronic components provided on the metal base circuit board;
An electronic device comprising:

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