JP2023038748A - Heated bonding material stuck with bond essentially consisting of metal nanoparticle and second metal particle, and electric apparatus bonding method - Google Patents

Abstract

To provide a sheet-shaped bonding material having excellent bonding properties and handleability and providable at low cost in a sintered bonding material essentially consisting of metal fine particles.SOLUTION: A sheet-shaped heated bonding material is obtained by sticking a bond comprising metal nanoparticles coated with an organic matter essentially consisting of an alcohol having a carbon number of 18 or less or an alcohol derivative thereof or a carboxyl group-comprising compound or a mixture thereof, metal fine particles and a solvent to both the sides of a sheet-shaped metal support. This constitution can provide a sheet-shaped sintered bonding material having excellent bonding properties and handleability.SELECTED DRAWING: None

Description

The present invention provides a heating bonding material in which a bonding agent containing metal nanoparticles and second metal fine particles is attached to a metal support, a bonding method using the bonding material, and the manufacture of an electronic device using the bonding method. It is about the method.

2. Description of the Related Art In recent years, in the joining of electronic parts, the non-use of solder materials containing lead, which has a high environmental impact, has become widespread.
In addition, attempts have been made to change the material of chips from Si to SiC or GaN in order to improve the performance of semiconductors, particularly electronic components called power modules.
Therefore, a bonding material containing sintered metal fine particles using Ag or Cu metal nanoparticles is being studied instead of lead-free solder, which has a problem in heat resistance.

However, since the bonding material using fine metal particles made of Ag or Cu is used as a paste-like bonding material in which metal nanoparticles are mixed with a polymer dispersant or a solvent, it is difficult to apply it to the object to be bonded. In that case, the uniformity of coating thickness and loss of paste in the printing process have been problems.
In particular, the amount of loss that occurs during the printing process is not much different from that of solder materials of the same shape, but the materials used as raw materials are ultrafine Ag and Cu nanoparticles. Since particles are very expensive, even a small amount of loss leads to an increase in production cost, which is a big problem.

Therefore, in order to solve the above problems, Patent Document 1 discloses a technique related to a sheet-like sinter-bonding sheet that contains conductive metal fine particles and can be bonded in a sintering process.
In addition, in Patent Document 2, metal fine particles having an average primary particle size of 5 to 500 nm, in which both sides of a metal layer made of a metal bulk are coated with a polymer dispersant, are dispersed in a solvent, and the dispersion is formed into a film. A technique of a heat bonding material is disclosed.

However, in the technique disclosed in Patent Document 1, since the composition for sintering bonding containing a conductive metal contains a thermally decomposable polymer binder, the heat bonding material disclosed in Patent Document 2 However, since the metal fine particles are coated with a polymer dispersant, problems remain in bonding characteristics, particularly bonding strength.

International publication WO2019/092959 JP 2018-103189 A

The problem that the invention is trying to solve

To provide a sheet-like bonding material that is excellent in bonding characteristics and handleability and can be provided at a low cost in a sintering type bonding material containing metal fine particles such as metal nanoparticles as a main component.

In the present invention, a support made of a plate-like metal and both sides of the support are coated with an organic material containing an alcohol having 18 or less carbon atoms or a derivative of the alcohol, a compound containing a carboxyl group, or a mixture thereof as a main component. It is possible to provide a sheet-shaped sintered bonding material with excellent bonding characteristics and handling properties by forming a sheet-shaped thermal bonding material to which a bonding agent containing metal nanoparticles, metal fine particles, and a solvent is attached. bottom.

According to the present invention, it is possible to provide a sheet-shaped sintering type bonding material that is excellent in bonding characteristics and handling properties and is inexpensive. It can be expected to be widely applied to semiconductor parts, electronic devices using such parts, and joints that require high thermal conductivity properties, such as joints of heat sinks.

BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic diagram of the sheet-shaped baking type|mold bonding material which concerns on one Embodiment of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION A sheet-like sintered bonding material according to an embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a sheet-like sintered bonding material 1 (hereinafter referred to as a "sheet-like bonding material") according to one embodiment of the present invention includes metal nanoparticles and a second and a bonding agent 2 containing a solvent (hereinafter referred to as "bonding agent") is adhered.

The metal support 3 that can be used for the sheet-like bonding material 1 of the present invention may be flat and have a uniform thickness, and the shape is not limited as long as the bonding agent can be adhered to both surfaces. For example, even if there are holes in the support or irregularities on the surface of the support, there is no problem even if other processing is applied, and a mesh shape or the like can be exemplified.
Also, usable metals are not limited as long as the effect of the present invention is achieved, and Cu, Ag, Au, Pt, Pd, Ni, and alloys thereof can be exemplified. Cu is preferred.
The metal support may have the above composition, for example, Cu alone, an alloy of Cu and other metals, or Cu plated with Ni, Au, Ag, or the like, and may be incorporated into electronic parts, semiconductor parts, or the like. It does not matter if it is a metal that matches the application of the part or product that will be used.

On the other hand, with respect to the size of the metal support 3, considering the bonding characteristics such as thermal conductivity and electrical conductivity and the bonding reliability, there is no particular limitation on the thickness within the range in which the effects of the present invention can be obtained. It is preferably less than 50 μm, and more preferably 10 μm to less than 50 μm in consideration of workability and cost during production.
In the case where the metal support 3 has holes or is a mesh, the size and number of the holes are not limited within the scope of the effects of the present invention. There is also no limit to the size of the mesh openings in the mesh.

Regarding the bonding agent 2 that can be used in the sheet-like bonding material of the present invention, if the organic material that coats the metal nanoparticles is an alcohol or an alcohol derivative having 18 or less carbon atoms, or a carboxylic acid, or a mixture thereof, it is particularly There are no restrictions, and alcohols having 18 or less carbon atoms or alcohol derivatives thereof, compounds containing a carboxyl group, or mixtures thereof are preferred.
In addition, the metal that serves as the metal nucleus of the metal nanoparticles that can be used in the bonding agent 2 is not particularly limited as long as the effects of the present invention are exhibited, and silver and copper are preferred. Although there is no particular limitation as long as the effect of the present invention is achieved, metal nanoparticles having an average primary particle size of 100 nm or less are preferred in consideration of the temperature during sintering.

As for the second fine metal particles that can be used in the bonding agent 2, Ag and Cu can be exemplified as long as the effect of the present invention is achieved without any particular limitation on the type and size of the element.
For example, when the material is copper, the average particle size of the primary particles is preferably 0.1 to 10 μm, and if it is 0.1 μm or less, treatment such as coating with an organic substance is required to prevent oxidation and bonding of particles. Therefore, there is a possibility that prescription restrictions may occur in order to use it for the bonding agent 3 .
Moreover, in the case of silver, it is the same as the above-mentioned copper.

The solvent that can be used for the bonding agent 2 is not particularly limited as long as the effect of the present invention is achieved, but an organic solvent containing no nitrogen or sulfur in its composition is preferable, and alcohols are more preferable.
As alcohols, for example, alcohols having 4 to 10 carbon atoms such as pentanol, hexanol, heptanol, octanol, nonanol and decanol are suitable.
In addition to the above alcohols, terpene alcohols such as citronellol, isobornylcyclohexanol, and carveol are preferred.

Further, the compounding ratio of the metal nanoparticles, the second metal fine particles, and the solvent that can be used in the bonding agent 2 is such that the effect can be obtained when the sheet-like bonding material 1 of the present invention is processed. Although there is no particular limitation, when the bonding agent 2 is 100, the metal nanoparticles are 0 to 90 parts by mass, the second metal fine particles are 0 to 80 parts by mass, and the solvent is 1 to 30 parts by mass. are preferable ranges.
In addition to the metal nanoparticles, the second metal fine particles, and the solvent, the bonding agent 2 contains an activator such as an organic acid, an antioxidant, a viscosity modifier, and the like within the scope of the effects of the present invention. They may be mixed as appropriate.

The method for producing the sheet-like bonding material 1 of the present invention is not particularly limited as long as the bonding agent 2 is adhered to the metal support 3 and a uniform film thickness can be maintained.
For example, after applying the bonding agent 2 to a thickness of 30 to 50 μm on one side of a Cu foil with a thickness of about 30 μm, leave it on a hot plate at 100° C. for about 60 seconds to dry, and then the opposite side of the uncoated Cu foil. The same operation is performed in , and the bonding agent 2 is adhered to both surfaces of the metal support 3, whereby the sheet-like bonding material 1 can be produced.
At that time, the more flat the surface of the bonding agent 2 to be adhered to both surfaces of the metal support 1, the better the bonding characteristics during sintering. It is preferable to achieve a uniform coating thickness using a dedicated jig or device.
When the bonding agent 2 is attached to both surfaces of the metal support 1, the bonding agent 2 is added with an organic solvent such as alcohol, acetone, toluene, dimethyl ketone, methyl ethyl ketone, or cyclohexane, and then applied to the metal support 1. It does not matter if the quality is improved.

Furthermore, considering that the thickness of the sheet-like bonding material 1 of the present invention is reduced to 3/10 to 7/10 compared to the thickness before sintering due to evaporation of the solvent and sintering of metal particles contained during sintering. By designing and joining, it leads to performance improvement and deterioration prevention of electronic parts to be joined.

Next, the sheet-like bonding material of the present invention will be described based on examples, but the present invention is not limited to the examples.
(Preparation of sample)
1. Metal support A commercially available oxygen-free copper foil with a thickness of 20 μm is prepared, cut into a size of 10 × 10 mm,
A metal support was used.
2. Bonding agent Alconanosilver paste ANP-8 manufactured by Applied Nanoparticles Laboratory Co., Ltd. was used.
3. Manufacturing method On one side of the copper foil cut to the specified size, a thickness of 30 μm with an opening of 9 × 9 mm
Alconano silver paste ANP as a bonding agent using a stainless steel stencil
-8 was applied.
Next, place the copper foil coated with the alconano silver paste ANP-8 on a hot plate at 100° C. so that the uncoated surface is in contact with the heating surface, leave it for 60 seconds, and then cool it to room temperature.
After cooling, the alconano silver paste ANP- was applied to the uncoated copper foil surface using a stencil.
8 is applied, then dried in the same manner on a hot plate at 100 ° C., then cooled,
It was used as a sheet-like bonding material sample.

(Evaluation method for sheet-like bonding material sample)
Between a copper test piece A (size: thickness 2 mm, diameter 5 mm) and a copper test piece B (size: thickness 2 mm, diameter 5 mm), place the sheet-like bonding material sample prepared by the above method, Using a firing device (upper and lower pulse heat unit bonding device) manufactured by Avionics, firing was performed under the conditions of a firing temperature of 300 ° C., a holding time of 180 seconds, 30 MPa, and an air atmosphere. It was used as an evaluation sample.

(Evaluation method)
The bonding strength of the evaluation sample was measured using a Tensilon universal tester manufactured by A&D.
Table 1 shows the measurement results.
As a comparative example, a comparative sample was prepared and confirmed by bonding a similar copper test piece using Alconano silver paste ANP-8.
In addition, the manufacturing conditions of the comparative sample are as follows.
・ 50 μm coating thickness on copper test piece (applied to copper test piece using a stainless steel stencil)
Firing conditions Pre-drying: After applying Alconano silver paste ANP-8 to a copper test piece, leave it on a hot plate set at 130°C for about 90 seconds, then leave it to cool at room temperature for about 30 minutes.
Comparative sample: A copper test piece was placed on the ANP-8 nanosilver paste layer that had been pre-dried and cooled to room temperature, and fired under the same conditions as in the evaluation method for the sheet-like bonding material sample to obtain a comparative sample.

Table 1 shows the evaluation results.

From Table 1, it can be determined that Example 1 has a function as a bonding material for semiconductors because the bonding strengths of Examples and Comparative Examples show equivalent values.
Moreover, when observing the fracture surface of the evaluation sample, it was confirmed that both Example 1 and Comparative Example 1 fractured at the sintered layer.
Furthermore, in Example 1, when the adhesion state of the sintered layer of the copper test piece after the bonding strength measurement of the evaluation sample was confirmed, it was almost uniformly adhered to the entire surface of the test piece, and the adhesion state was compared with that of Comparative Example 1. Since the uniformity is high even when the material is used, it can be expected to improve the bonding quality compared to the paste-like sintering type bonding material for bonding when the area of the body to be bonded is large and the body to be bonded is large. Aptitude for large-area bonding can be expected.

1: Sheet-like bonding material of the present invention 2: Bonding agent 3: Metal support

Claims (4)

A bonding material obtained by attaching a bonding agent mainly composed of metal nanoparticles, second metal fine particles, or both to both surfaces of a support made of a plate-like metal,
The plate-shaped metal support has a thickness of less than 50 μm and is at least one metal element or alloy selected from Cu, Ag, Au, Pt, Pd, and Ni,
The metal nanoparticles attached to the indicator and the metal nanoparticles of the bonding agent mainly composed of the second metal fine particles are selected from Ag and Cu, or an alloy composed of both, or Each consists of both single metals,
The metal of the second metal fine particles is a single metal selected from Ag and Cu, or an alloy composed of both, or both of single metals,
The metal nanoparticles are coated with an organic substance and have an average particle size of 100 nm or less, and the metal fine particles have an average particle size of 10 μm or less;
The bonding agent contains at least one or more of metal nanoparticles and second metal fine particles, and a solvent, and the bonding agent is applied to both surfaces of the plate-like metal support to a thickness of 300 μm or less, or after being applied, A bonding material characterized by being in a dried state. 2. The bonding material according to claim 1, wherein the organic substance covering the metal nanoparticles is an alcohol having 18 or less carbon atoms or an alcohol derivative thereof, a compound containing a carboxyl group, or a mixture thereof. A bonding method comprising using the bonding material according to claim 1 and claim 2 and performing bonding using a heat treatment process. An electric device, an electronic device, a semiconductor component, and a heat dissipation component joined by the joining method according to claim 3.

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