TWI487446B - A composite material having a composite structure - Google Patents

Description

Bonding material with composite structure

The present invention relates to a joining material, and more particularly to a joining material having a composite structure.

Semiconductors, electronic circuits, electronic machinery, etc. generally fuse various electronic components through solder to ensure their electrical conductivity and product reliability. However, the solder used in the past is mainly an alloy of tin and lead. Since lead is a toxic heavy metal, it not only causes environmental pollution, but also causes serious harm to the human body.

With the miniaturization of semiconductor devices and electronic components, the possibility of bonding applications using nanomaterials has gradually attracted attention. When the size of an object enters the nanometer scale, it has its small size effect, surface effect, etc. It has shown many unique properties, such as a decrease in melting point, improved reaction performance, etc., which has become a hot trend in research and development in recent years. Taking the current popular nano silver particles as an example, because of its low sintering temperature, low electrical resistance and low melting point, it can be applied to conductive applications or electronic component bonding by simple heat treatment. Therefore, when a nano silver particle is used as a bonding material for a semiconductor device or an electronic component or the like, sintering bonding can be performed without high heat damage to reduce damage to an element or a substrate.

However, although the bonding application using nano materials has many advantages, in order to uniformly and stably disperse the nano-sized powder, it is generally necessary to additionally add a dispersing aid to stabilize the nano-powder and avoid the naphthalene. The aggregation of the rice flour and the dispersing aid attached to the surface of the nanopowder tend to remain during the sintering process, which affects the strength of the joint. In addition, nanomaterials are not easy to mass-produce, and at the same time have the problem of excessive production costs, so they still cannot be widely used.

Based on the development and application of the above-mentioned bonding materials, how to effectively improve the bonding strength, and to make a bonding material instead of lead metal in a simple process and a low production cost is an important goal of research and improvement of the present invention.

Accordingly, it is an object of the present invention to provide a joining material having a composite structure having high development value and high joint strength.

Thus, the present invention has a composite structure of a bonding material which, after sintering, can be used to bond two objects, comprising a core, and a plurality of nanoparticles surrounding the core. The core is composed of a metallic material and has an average particle diameter of not more than 1000 nm; the nanoparticles are composed of a metallic material and may be the same as or different from the metallic material of the core.

Preferably, the foregoing bonding material having a composite structure in which the nano particles are uniformly dispersed on the surface of the core, and in order to have a sufficient surface for dispersing the nanoparticles, the particle diameter of the core is The particle diameter of the nanoparticles is 10 times or more.

Preferably, the foregoing bonding material having a composite structure, wherein the core has an average particle diameter of not more than 300 nm.

Preferably, the foregoing bonding material having a composite structure, wherein the nano particles have an average particle diameter of not more than 100 nm.

More preferably, the aforementioned bonding material having a composite structure in which the average particle diameter of the nanoparticles is not more than 20 nm.

Preferably, the foregoing bonding material having a composite structure, wherein the core constituent material is selected from the group consisting of gold, silver, copper, and aluminum.

More preferably, the aforementioned bonding material having a composite structure in which the constituent material of the core is selected from silver.

Preferably, the foregoing bonding material having a composite structure, wherein the constituent materials of the nano particles are selected from the group consisting of gold, silver, copper, and aluminum.

More preferably, the aforementioned bonding material having a composite structure in which the constituent materials of the nano particles are selected from silver.

Preferably, the foregoing bonding material having a composite structure, wherein the bonding material is sintered after being sintered at 150 ° C to 400 ° C, may be used to bond the copper metal, and the joint shear strength of the joint is greater than 20 MPa.

2‧‧‧Material materials with composite structure

21‧‧‧ core

22‧‧‧Nano particles

3‧‧‧Shut joint strength test equipment

31‧‧‧First joint sample

32‧‧‧Second joint sample

33‧‧‧ propeller

34‧‧‧ joints

Other features and advantages of the present invention will be apparent from the embodiments of the present invention. FIG. 1 is a schematic view showing a preferred embodiment of the present invention having a composite structure; FIG. 2 is a Distribution map showing the silver powder obtained by spray pyrolysis The average particle size distribution of the material; FIG. 3 is a transmission electron microscope diagram illustrating the actual state of the bonding material having the composite structure of the present invention; FIG. 4 is a schematic view showing the apparatus for performing the shear joint strength test; And Figure 5 is a histogram showing the test results of the shear joint strength test with different joint materials.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 1, a preferred embodiment of a bonding material 2 having a composite structure comprises a core 21 and a plurality of nanoparticles 22 surrounding the core. The bonding material 2 having a composite structure can be used after sintering. Engage the two objects.

The core 21 is composed of a metal material and has an average particle diameter of not more than 1000 nm. Preferably, the core 21 has an average particle diameter of not more than 300 nm.

The nanoparticles 22 are uniformly dispersed on the surface of the core 21 and are composed of a metal material. The average particle diameter of the nano particles 22 is not more than 100 nm, preferably, the average particle size of the nano particles 22. The diameter is no more than 20 nm. The particle diameter of the core 21 is 10 times or more the particle diameter of the nanoparticles 22 so that the nanoparticles 22 can be sufficiently coated and covered on the surface of the core 21. Further, it is to be noted that the nanoparticles 22 may be uniformly dispersed on the surface of the core 21 in the form of a single layer or a plurality of layers. Profit The core 21 is used to provide the surface in which the nanoparticles 22 are dispersed, so that no additional dispersing aid is required, and the strength of the joint is not affected by the residual of the dispersing aid during the subsequent sintering.

The core 21 and the constituent materials of the nano particles 22 may be selected from the group consisting of gold, silver, copper, and aluminum, and may be the same or different. Since silver is the metal with the highest conductivity, the price is cheaper than gold, and compared. In copper and aluminum, silver does not easily form an oxide on the surface at a high temperature. Therefore, in the preferred embodiment, the core 21 and the constituent materials of the nano particles 22 are selected from silver. Description.

In detail, the bonding material 2 having the composite structure of the present invention may be, for example, a chemical reduction method, a precipitation method, a Sol-gel method, or a spray pyrolysis method. Different production methods are prepared, wherein the spray pyrolysis method has the advantages of low cost and mass production because it is a rapid and continuous process, and does not require the use of an organic solvent, so the spray pyrolysis method is selected as the present invention. A method of preparing a bonding material 2 of a composite structure.

Specifically, the bonding material 2 having the composite structure of the present invention is prepared by a spray pyrolysis method by first dissolving a precursor solution containing silver ions in deionized water to form an aqueous solution, and then dispersing the aqueous solution into a fine mist by an ultrasonic fogger. The droplets are sent to a tubular heating furnace, and after passing through the tubular heating furnace, after solvent evaporation, solute supersaturation precipitation, pyrolysis and oxidation reaction, the particles can be collected by electrostatic dust collection technology. Powder material. Spray pyrolysis is controlled by the flow rate of the carrier gas Reasonable time, so the liquid phase can be removed in a short time to get a clean powder, and because deionized water is used as a solvent without polluting the environment, the spray pyrolysis method does not require special equipment and is expensive. The raw materials produce high purity clean powder.

Referring to FIG. 2, FIG. 2 is a graph showing the average particle size distribution of the silver powder material obtained by spray pyrolysis. The silver powder material is mainly divided into a particle size of about 20 nm and a particle diameter of 100 nm to 300 nm. In two groups, the powder having a particle diameter of about 20 nm is the nanoparticle 22 of the present invention, and the powder having a particle diameter of 100 nm to 300 nm is the core 21 of the present invention, and then, After the silver powder material is added to the solvent and mixed and stirred, the smaller particle diameters of the nano particles 22 are dispersed on the surface of the core 21, and the composite structure of the present invention as shown in FIG. 3 can be obtained. Bonding material 2. When the bonding application is actually performed, the silver powder materials may be firstly added to the solvent to be mixed and stirred, so that the nano particles 22 having a smaller particle diameter are dispersed on the surface of the core 21 to form a bonding material of the composite structure. The bonding material may be applied to the surface to be joined.

By utilizing the low melting point characteristics of the nanoparticles 22, the nanoparticles 22 can be melted at a lower sintering temperature, and the core 21, the nanoparticles 22, and The conjugates are fused together. Furthermore, since the particle size scale of the nanoparticles 22 is in the nanometer size, the contact area with the surface of the object to be joined can be increased, which contributes to an increase in bonding to improve the bonding strength.

In order to make the work of the joint material 2 having the composite structure of the present invention It is more clear that the bonding material of the present invention is bonded to the bonding material of the sub-micron and nano-sized dimensions, and the shear joint strength of the joint is compared, and the bonding material having the composite structure of the present invention is explained. 2 advantages in practical applications.

Referring to FIG. 4, FIG. 4 is a schematic diagram of an apparatus for performing a shear joint strength test. The shear joint strength testing apparatus 3 includes a first joint sample 31 and a second joint sample 32 disposed relative to the first joint sample 31. And a pusher 33 for pushing the first joint sample 31. In the shear strength test, the first and second joint samples 31 and 32 are all selected from copper metal.

When the test is performed, the bonding material to be tested is first contacted with the first and second bonding samples 31, 32 and interposed between the first and second bonding samples 31, 32, and the sintering temperature is controlled to 250 ° C, and the bonding is performed. The pressure is 10 MPa, and the bonding material to be tested is melted by heating and pressing for 30 minutes to form a joint portion 34, and then cooled to solidify the joint portion 34, that is, the first and second joint samples 31, 32 are completed. Engagement. Next, the pusher 33 pushes the pusher at the boundary of the first joined sample 31 until the joint portion 34 cannot withstand the pushing pressure, and the first and second joined samples 31, 32 are separated.

Referring to FIG. 5, FIG. 5 is a result of the shear joint strength test of the joint of the present invention and the joint material of the submicron and nanometer size, and the joint of the shear joint strength test. The joint strength of the joint material 2 of the structure is 29 MPa, while the sub-micron and nano The shear joint strength of the graded joint material is 16 MPa and 26 MPa, respectively, which are lower than the shear joint strength of the present invention, although the shear joint strength of the nano-sized joint material is bonded to the composite structure of the present invention. The material 2 is similar, but the bonding material of the nano-size is not easy to be produced on a large scale, and the production cost is high, and the production cost of the bonding material 2 having the composite structure of the present invention is about 30% higher.

Furthermore, since the surface of the nano-sized metal powder is mostly adhered with a layer of a dispersing aid, it tends to remain in the process of sintering to affect the strength of the joint, and the joint material 2 and the nanostructure of the present invention have a composite structure. Compared with the joint material of the grade size, the probability of generating voids between the grains after sintering is low, so that it is less likely to cause damage and affect the joint strength when pushed by an external force.

In summary, the present invention has a composite structure of the bonding material 2, and the nanoparticles 22 surround the surface of the core 21, and the nanoparticles 22 have a nanometer size and a low melting point. The characteristics of the contact area are improved, and the sintering temperature is lowered and the strength of the joint is improved. The invention can be widely applied to different industries and fields, and has high development value and wide application range in the market, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

2‧‧‧Material materials with composite structure

21‧‧‧ core

22‧‧‧Nano particles

Claims (10)

A bonding material having a composite structure, which can be used for joining two objects after sintering, comprising: a core composed of a metal material and having an average particle diameter of not more than 1000 nm; and a plurality of nano particles surrounding the core, made of metal The material is constructed and may be the same or different from the metal material of the core. The bonding material having a composite structure according to claim 1, wherein the nano particles are uniformly dispersed on a surface of the core, and in order to have a sufficient surface for dispersing the nanoparticles, the particle diameter of the core It is 10 times or more of these nano particles. The bonding material having a composite structure according to claim 1, wherein the core has an average particle diameter of not more than 300 nm. The bonding material having a composite structure according to claim 1, wherein the nano particles have an average particle diameter of not more than 100 nm. The bonding material having a composite structure according to claim 4, wherein the nano particles have an average particle diameter of not more than 20 nm. The bonding material having a composite structure according to claim 1, wherein the core constituent material is selected from the group consisting of gold, silver, copper, and aluminum. The bonding material having a composite structure according to claim 6, wherein the constituent material of the core is selected from silver. The bonding material having a composite structure according to claim 1, wherein the constituent materials of the nano particles are selected from the group consisting of gold, silver, copper, and aluminum. The bonding material having a composite structure according to claim 8, wherein the constituent material of the nano particles is selected from silver. The bonding material having a composite structure according to claim 1, wherein the bonding material is used to bond a copper metal after sintering at 150 ° C to 400 ° C, and the joint has a shear joint strength of more than 20 MPa.