JP7141864B2 - Electronic component mounting substrate and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic component mounting board and a manufacturing method thereof, and in particular, an electronic component such as a semiconductor chip is mounted on one surface of a metal plate of a metal-ceramic bonding board in which a metal plate made of aluminum or an aluminum alloy is bonded to a ceramic substrate. The present invention relates to an attached electronic component mounting board and a manufacturing method thereof.

Conventionally, power modules have been used to control large currents in electric vehicles, trains, machine tools, and the like. In a conventional power module, a metal-ceramic insulating substrate is fixed to one side of a metal plate or composite material called a base plate, and a semiconductor chip is fixed on the metal plate of this metal-ceramic insulating substrate by soldering. It is

In recent years, a silver paste containing fine silver particles is used as a bonding material, the bonding material is interposed between the objects to be bonded, and the objects to be bonded are heated for a predetermined time while applying pressure to sinter the silver in the bonding material. It has been proposed to join objects (such as silver-plated copper materials) to each other by using such a joining material instead of solder. Attempts have been made to fix electronic components such as semiconductor chips on metal plates of ceramic insulating substrates.

It has also been proposed to form a nickel or nickel alloy plating film on one surface of a metal plate made of aluminum or an aluminum alloy, and to bond an electronic component thereon with a silver bonding layer (for example, Patent Document 2). reference).

JP 2011-80147 (paragraph numbers 0014-0020, 0085) JP 2014-130989 (paragraph number 0007-0011)

However, as in Patent Document 1, an electronic component is bonded to a silver-plated copper material with a bonding material, and as in Patent Document 2, an electronic component is bonded to a metal plate plated with nickel or a nickel alloy with a silver bonding layer. When a power semiconductor is used as an electronic component and a power cycle test is performed in which the power semiconductor is turned on and off several tens of thousands of times, the power semiconductor may separate from the metal plate.

Therefore, in view of such conventional problems, the present invention provides an electronic component mounting substrate in which electronic components are mounted on a metal plate made of aluminum or an aluminum alloy, even if a power cycle test is performed, the electronic components are removed from the metal plate. An object of the present invention is to provide an electronic component mounting substrate and a method for manufacturing the same, which can prevent peeling.

As a result of intensive research to solve the above problems, the present inventors have found that, in a method for manufacturing an electronic component mounting substrate in which an electronic component is mounted on one surface of a metal plate made of aluminum or an aluminum alloy, one side of the metal plate A nickel film, a palladium film, and a silver film are formed in this order on the surface of the silver film, and after applying silver paste on the silver film and placing electronic components on it, the silver in the silver paste is sintered to form a silver film. By forming a bonding layer and bonding the electronic component to one surface of the metal plate with this silver bonding layer, it is possible to prevent the electronic component from peeling off from the metal plate even when a power cycle test is performed. The inventors have found that it is possible to provide a component mounting board and a manufacturing method thereof, and have completed the present invention.

That is, a method for manufacturing an electronic component mounting substrate according to the present invention is a method for manufacturing an electronic component mounting substrate in which an electronic component is mounted on one surface of a metal plate made of aluminum or an aluminum alloy, in which, on one surface of the metal plate, A nickel film, a palladium film, and a silver film are formed in this order, and after applying silver paste on the silver film and placing electronic components on it, the silver in the silver paste is sintered to form a silver bonding layer. The silver bonding layer is used to bond the electronic component to one surface of the metal plate.

In this method of manufacturing an electronic component mounting board, the nickel film preferably has a thickness of 0.5 to 10 μm, the palladium film preferably has a thickness of 0.05 to 3 μm, and the silver film has a thickness of 0.05 to 3 μm. It is preferably between 0.05 and 5 μm. Moreover, it is preferable that the surface to be joined to one surface of the metal plate of the electronic component is coated with at least one metal selected from the group consisting of gold, silver, copper and palladium, or an alloy thereof. Also, it is preferable to bond one surface of the ceramic substrate to the other surface of the metal plate.

Further, the electronic component mounting substrate according to the present invention is an electronic component mounting substrate in which an electronic component is mounted on one surface of a metal plate made of aluminum or an aluminum alloy, wherein one surface of the metal plate is coated with a nickel film and a palladium film. A silver film is formed in this order, and an electronic component is bonded to the silver film by a silver bonding layer.

In this electronic component mounting board, the nickel film preferably has a thickness of 0.5 to 10 μm, the palladium film preferably has a thickness of 0.05 to 3 μm, and the silver film has a thickness of 0.05. It is preferably ˜5 μm. Moreover, it is preferable that the surface to be joined to one surface of the metal plate of the electronic component is coated with at least one metal selected from the group consisting of gold, silver, copper and palladium, or an alloy thereof. Also, it is preferable that one surface of the ceramic substrate is bonded to the other surface of the metal plate.

According to the present invention, in an electronic component mounting board in which electronic components are mounted on a metal plate made of aluminum or an aluminum alloy, it is possible to prevent the electronic components from peeling off from the metal plate even when a power cycle test is performed. An electronic component mounting board and a manufacturing method thereof can be provided.

1 is a sectional view of an embodiment of an electronic component mounting substrate according to the present invention; FIG. FIG. 2 is a perspective view of the electronic component mounting substrate of FIG. 1;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an electronic component mounting board and a method for manufacturing the same according to the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, in the embodiment of the electronic component mounting board according to the present invention, a nickel film 12 is formed on one main surface of a metal plate (electronic component mounting metal plate) 10 having a substantially rectangular planar shape. A palladium film 14 and a silver film 16 are formed in this order, and an electronic component 20 is bonded to the surface of the silver film 16 by a silver bonding layer 18 (including a sintered body of silver). Further, one main surface of a ceramic substrate 22 having a substantially rectangular planar shape is bonded to the other main surface of the metal plate 10, and a heat radiation metal having a substantially rectangular planar shape is attached to the other main surface of the ceramic substrate 22. A plate (metal base plate) 24 may be joined.

The electronic component mounting metal plate 10 and the heat radiation metal plate 24 are made of aluminum or an aluminum alloy, and from the viewpoint of conductivity and heat dissipation, preferably 99.5% by mass or more, more preferably 99.9% by mass of aluminum It preferably contains

The ceramic substrate 22 is preferably a ceramic substrate that exhibits excellent insulation even when a power semiconductor is mounted as an electronic component and a large current and high voltage are applied. Aluminum nitride (AlN), alumina (Al ₂ O ₃ ) and silicon nitride (SiN) as main components.

A nickel film 12 made of nickel or a nickel alloy is formed on one main surface of the electronic component mounting metal plate 10 (at least the portion thereof where the electronic component 20 is bonded by the silver bonding layer 18). The thickness of this nickel coating 12 is preferably 0.5 to 10 μm. If the nickel film 12 is too thin, the adhesion with the palladium film 14 will be reduced, and if it is too thick, the conductivity will be reduced and the manufacturing cost will increase. The nickel film 12 is preferably a nickel plating film or a nickel alloy plating film (containing 85% by mass or more of nickel), and can be formed by electroplating or electroless plating. In the case of a nickel alloy plating film, it may be a Ni—P alloy plating film or a Ni—B alloy plating film. In the case of a Ni—P alloy plating film, the P concentration is preferably 6 to 11 mass %, more preferably 6 to 8 mass %, in order to obtain good adhesion with the palladium film 14 . This P concentration can be adjusted with a plating solution.

A palladium film 14 made of palladium or a palladium alloy is formed on the surface of the nickel film 12 . By providing the palladium film 14 between the nickel film 12 and the silver film 16, the adhesion between the nickel film 12 and the silver film 16 can be improved. The thickness of the palladium film 14 is preferably 0.05-3 μm. If the palladium film 14 is too thin, the adhesion to the nickel film 12 and the silver film 16 will be lowered, and if it is too thick, the amount of expensive palladium used will increase, increasing the manufacturing cost. The palladium film 14 is preferably a palladium plating film or a palladium alloy plating film (containing 95% by mass or more of palladium), and can be formed by electroplating or electroless plating.

A silver film 16 made of silver or a silver alloy is formed on the surface of the palladium film 14 . This silver film 16 can improve adhesion with the silver bonding layer 18 . The thickness of the silver film 16 is preferably 0.05-5 μm. If the silver film 16 is too thin, the adhesion with the silver bonding layer 18 will be reduced, and if it is too thick, the manufacturing cost will increase. The silver film 16 is preferably a silver plating film or a silver alloy plating film (containing 95% by mass or more of silver), and can be formed by electroplating or electroless plating.

In addition, the surface to be bonded to one main surface of the metal plate 10 of the electronic component 20 is made of at least one metal selected from the group consisting of gold, silver, copper and palladium, or an alloy thereof, and the silver bonding layer 18 It is preferably coated with a metal that can be bonded to and is preferably plated (by electroplating or electroless plating) with at least one metal selected from the group consisting of gold, silver and palladium or an alloy thereof .

In the embodiment of the method for manufacturing an electronic component mounting board according to the present invention, in the method for manufacturing an electronic component mounting board in which an electronic component 20 is mounted on one main surface of a metal plate 10 made of aluminum or an aluminum alloy, the metal plate 10 A nickel film 12, a palladium film 14, and a silver film 16 are formed in this order on one main surface of (at least a portion of which silver paste is applied), a silver paste is applied on the silver film 16, and an electron is applied thereon. After placing the component 20 , the silver in the silver paste is sintered to form the silver bonding layer 18 , and the electronic component 20 is bonded to one surface of the metal plate 10 by this silver bonding layer 18 .

The sintering of silver in the silver paste is preferably carried out by heating to 200 to 500.degree. C., more preferably by heating to 220 to 400.degree. The heating time during this sintering is preferably 1 to 10 minutes. Moreover, this sintering can be performed by heating without pressure, but may be performed by heating while pressing the electronic component 20 against the metal plate 10 . The pressure applied during this sintering may be 10 MPa or less, preferably 2 to 10 MPa, more preferably 3 to 8 MPa.

Further, one main surface of a ceramic substrate 22 having a substantially rectangular planar shape is bonded to the other main surface of the metal plate 10, and a heat radiation metal having a substantially rectangular planar shape is attached to the other main surface of the ceramic substrate 22. A plate (metal base plate) 24 may be joined. In this case, after bonding between the metal plate 10 and the ceramic substrate 22 and between the ceramic substrate 22 and the metal base plate 24, on one main surface of the metal plate 10 (the surface to which the electronic component 20 is bonded), A nickel film 12, a palladium film 14, and a silver film 16 are formed in this order, a silver paste is applied on the silver film 16, an electronic component 20 is arranged, and then the silver in the silver paste is sintered to form a silver bonding layer. 18 is formed, and the electronic component 20 is bonded to one main surface of the metal plate 10 by this silver bonding layer 18 . In addition, in the bonding between the metal plate 10 and the ceramic substrate 22 and between the ceramic substrate 22 and the metal base plate 24, after placing the ceramic substrate 22 in a mold (not shown), both main surfaces of the ceramic substrate 22 are brought into contact with each other. The metal plate 10 and the metal base plate 24 are formed on the respective main surfaces of the ceramic substrate 22 by pouring molten aluminum or aluminum alloy in such a manner as to cool and solidify the molten aluminum or aluminum alloy so as to be directly bonded. preferable.

In addition, as the silver paste, a paste containing fine silver particles that can be sintered at a temperature of 500 ° C. or less can be used, and the average primary particle diameter coated with an organic compound having 8 or less carbon atoms (preferably 6 to 8) It is preferable to use a bonding material (for example, PA-HT-1503M-C manufactured by DOWA Electronics Co., Ltd.) in which fine silver particles of 1 to 200 nm are dispersed in a dispersion medium (preferably a polar solvent). A bonding material (for example, PA- _HT- 1001L) may be used.

Examples of an electronic component mounting board and a method of manufacturing the same according to the present invention will be described below in detail.

A ceramic substrate made of AlN (aluminum nitride) having a size of 45 mm × 25 mm × 0.6 mm is placed in the mold, and molten aluminum of 99.9% by mass is poured so as to contact both main surfaces of the ceramic substrate. After heating, the molten metal is cooled and solidified to form a metal plate (for mounting electronic parts) of 45 mm x 23 mm x 0.4 mm and a metal plate of 45 mm x 23 mm x 0.4 mm on each main surface of the ceramic substrate. A metal base plate (for heat radiation) was formed and directly bonded to the main surface of each ceramic substrate to produce a metal-ceramic bonded substrate.

Next, as pretreatment for plating, degreasing, chemical polishing and pickling are performed, and after double zincate treatment (twice zinc substitution), the metal-ceramic bonded substrate is coated with an electroless Ni-P plating solution (Uemura Kogyo Co., Ltd.). Nimden NPR-4 (manufactured by the company) was used to form an electroless Ni-P alloy plating film (with a P concentration of 7% by mass and the balance being Ni-free) on the surface of a metal plate (for mounting electronic components) with a thickness of 4 μm. Electrolytic Ni—P plating film) was formed.

Next, the metal-ceramic bonding substrate on which the Ni—P plating film was formed was treated with an autocatalytic reduction type electroless palladium plating solution as a metal plating solution having autocatalytic properties for electroless Ni—P alloy plating. A 0.1 μm-thick palladium plating film was formed on the Ni—P alloy plating film by immersion in (Altalea TDP-30-MW manufactured by Uyemura & Co., Ltd.).

Next, the metal-ceramic bonding substrate on which the palladium plating film is formed is immersed in an electroless silver plating solution (Argento RSD-4, manufactured by Uyemura & Co., Ltd.), thereby forming a 0.05 mm thick layer on the palladium plating film. A silver plating film of 1 μm was formed.

Next, a silver paste (NBE Tech, Nano Tach manufactured by LLC) is applied by screen printing to the electronic component mounting portion of the surface of the silver plating film on the metal plate (for mounting electronic components), and the electronic component is applied thereon. As a power semiconductor silicon chip (Si-IGBT chip manufactured by Fairchild, model number PCFG75N60SMW) whose bottom surface (back surface) is silver-plated (length 7.19 mm × width 6.74 mm × thickness 0.07 mm) is arranged. Then, the silver in the silver paste is sintered by heating at 250° C. for 10 minutes in the air without pressurization to form a silver bonding layer. A silicon chip was bonded to the plate. The thickness of the silver bonding layer after this bonding was about 30 μm.

A test power supply is connected to the electrodes of the silicon chip on the electronic component mounting substrate thus produced, and the additional current is set to 3 A and the additional voltage is set to 11 V, and the current is applied for 50 seconds and then not applied for 40 seconds. (Since the silicon chip is heated by turning on the current, the temperature of the silicon chip rises to about 175° C. after 50 seconds, and after 40 seconds by turning off the current, the silicon chip A power cycle test was conducted in which 20,000 cycles (.DELTA.T=130.degree. C.) in which the temperature of the chip drops to about 45.degree. Since there is a linear relationship between the gate-emitter voltage _Vge of the power semiconductor silicon chip and the temperature of the silicon chip, the linear relationship is obtained in advance, and the gate-emitter voltage V The temperature of the silicon chip was converted from _ge . The temperature rise (increase in transient thermal resistance) of the silicon chip after this power cycle test was less than 105% of the initial set value (175° C.), and no electrical abnormality occurred in the silicon chip.

In addition, when observing the joint between the metal plate (for mounting electronic components) and the silicon chip on the manufactured electronic component mounting substrate with an ultrasonic flaw detector (SAT) (FS100II manufactured by Hitachi Kenki Finetech Co., Ltd.), No defects such as voids were observed in the silver bonding layer, and no peeling of the silicon chip was observed.

Further, as a comparative example, instead of the electroless Ni-P plating solution of Example 1, an electroless Ni-P plating solution (Nimden SX manufactured by Uyemura & Co., Ltd.) was used to form an electroless Ni-P alloy plating film. Instead of forming a palladium plating film (electroless Ni-P plating film with a phosphorus concentration of 10% by mass and the balance being nickel) and immersing it in the autocatalytic reduction type electroless palladium plating solution of Example 1 , and a palladium activation treatment solution (Axemalta MPD-22 manufactured by Uyemura & Co., Ltd.), except that the activation treatment was performed in the same manner as in Example 1, to produce an electronic component mounting substrate. A power cycle test similar to that of Example 1 was performed on this electronic component mounting board. After 9,000 cycles, noise was generated in the voltage _Vge between the gate and the emitter, and the temperature of the silicon chip increased (transient heat). increase in resistance) exceeded 105% of the initially set value (175° C.), it was determined that an electrical abnormality had occurred in the silicon chip. In addition, when observing the joint between the metal plate (for mounting electronic components) and the silicon chip on the manufactured electronic component mounting board with the same ultrasonic flaw detector (SAT) as in the example, part of the silver plating film was observed. Detachment from the nickel plating film was confirmed, and when the silicon chip was touched, the silicon chip fell off easily.

REFERENCE SIGNS LIST 10 metal plate for mounting electronic component 12 nickel film 14 palladium film 16 silver film 18 silver bonding layer 20 electronic component 22 ceramic substrate 24 metal plate for heat dissipation (metal base plate)

Claims (10)

A method for manufacturing an electronic component-mounted substrate in which electronic components are mounted on one surface of a metal plate made of aluminum or an aluminum alloy and one surface of a ceramic substrate is bonded to the other surface, wherein the ceramic substrate is bonded to the other surface. A nickel film, a palladium film, and a silver film are formed in this order on one surface of the metal plate to which one surface is bonded . What is claimed is: 1. A method of manufacturing an electronic component mounting substrate, comprising the steps of: sintering silver in a silver paste to form a silver bonding layer; and bonding an electronic component to one surface of a metal plate by means of the silver bonding layer. 2. The method for manufacturing an electronic component mounting board according to claim 1, wherein the nickel film has a thickness of 0.5 to 10 μm. 3. The method for manufacturing an electronic component mounting board according to claim 1, wherein the palladium film has a thickness of 0.05 to 3 μm. 4. The method for manufacturing an electronic component mounting board according to claim 1, wherein the silver film has a thickness of 0.05 to 5 μm. The surface of the electronic component to be bonded to one surface of the metal plate is coated with at least one metal selected from the group consisting of gold, silver, copper and palladium or an alloy thereof, 5. The method for manufacturing an electronic component mounting board according to claim 1. An electronic component mounting board in which electronic components are mounted on one surface of a metal plate made of aluminum or an aluminum alloy and one surface of a ceramic substrate is bonded to the other surface, and one surface of the ceramic substrate is attached to the other surface. A nickel film, a palladium film, and a silver film are formed in this order on one surface of a metal plate to which is bonded, and an electronic component is bonded to the silver film by a silver bonding layer. mounting board. 7. The electronic component mounting board according to claim 6 , wherein said nickel film has a thickness of 0.5 to 10 μm. 8. The electronic component mounting substrate according to claim 6 , wherein said palladium film has a thickness of 0.05 to 3 μm. 9. The electronic component mounting board according to claim 6 , wherein said silver film has a thickness of 0.05 to 5 μm. The surface of the electronic component to be bonded to one surface of the metal plate is coated with at least one metal selected from the group consisting of gold, silver, copper and palladium or an alloy thereof, The electronic component mounting board according to any one of claims 6 to 9 .

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