KR20160024827A - Low temperature bonding method to be joined using multi coating layer - Google Patents

Abstract

The present invention relates to a low-temperature bonding method to bond members to be bonded using a multi-plated layer. The low-temperature bonding method using a multi-plated layer according to the present invention bonds members to be bonded using metal consisting of multi-plated layer which is formed by alternatingly plating at least two elements or alloy thereof as a bonding agent. According to the present invention, when performing low-temperature bonding using a multi-plated layer as a bonding agent, the bonding can be possible not only in vacuum status, inert gas, and reducing gas but also in the air using flux. Moreover, the costs of nano-bonding materials can be remarkably reduced since noble metals and base metals (for example, various metal elements such as copper, tin, zinc, nickel, etc.) can be used as a bonding agent by plating the base metals.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a low-temperature bonding method for a bonding material using a multi-

The present invention relates to a method of bonding a material to be bonded using a multilayer plating film, and more particularly, to a method of bonding a metal thin film of two or more kinds of nanometers in thickness in a process of reducing two or more kinds of metal salts contained in a plating solution through a pulse current And a method of joining at a low temperature by using it as a bonding medium (bonding material) after stacking.

Conventional bonding technology is to insert a brazing material (melting point of 450 ° C or higher for soldering, melting point of 450 ° C or lower for soldering) between the materials to be bonded such as brazing (brazing) or soldering (softening soldering) The bonding material is heated and bonded. At this time, the brazing material is in a bulk form and the composition is substantially the same throughout the brazing material and has a melting point according to the composition. In the diffusion bonding, the bonding material is brought into contact with each other without using a brazing filler metal, and the atoms of the surface to be bonded are mutually diffused and bonded by heating after heating or by using mechanical friction heat such as ultrasonic waves or friction.

On the other hand, a nano paste may be used for low-temperature bonding. This is due to the phenomenon that the melting point of the nano powder is lowered. Nanometer sized powders are unstable and easily aggregated with neighboring powders. It is known that the melting point of the nano powder is lower than the melting point of the original bulk material in the course of the addition of the powders. The melting point (T _M (d)) of the metal powder is lowered according to the particle diameter (d) as compared with the melting point (T _MB ) of the lump metal as in the following equation (Gibbs Thomson formula). Therefore, the lower the diameter d of the particles, the lower the melting point thereof.

A technology related to such nano multilayer manufacturing technology has been proposed in Patent Registration No. 0560296 and Published Patent Application No. 2013-0060544.

Hereinafter, a method of manufacturing a multilayered metal thin film disclosed in Patent Registration No. 0560296 and Laid-open Patent Application No. 2013-0060544 and a method and apparatus for forming a nano multi-layer coating layer will be briefly described.

1 is a view showing a method of manufacturing a multilayered metal thin film in Patent Registration No. 1085100 (hereinafter referred to as "Prior Art 1"). As shown in FIG. 1, a method for manufacturing a multilayered metal thin film according to the prior art 1 includes first forming a first titanium film on a semiconductor substrate 21 using an ionized physical vapor deposition (IPVD) (22) is deposited to a thickness of 50 Å to 500 Å. In this case, when the IPVD method is used, metal atoms separated by sputtering from a target are ionized to be grounded or accelerated toward a wafer to which an AC bias is applied, so that the linearity of the metal ions is utilized So that the diffusion preventing metal film is deposited with excellent step coverage.

A first titanium nitride layer 23 is deposited on the first titanium layer 22 to a thickness of 50 Å to 500 Å in the <002> direction of the first titanium layer 22. The first titanium nitride layer 23 is deposited using any one of physical vapor deposition (PVD), metal organic chemical vapor deposition (MOCVD), and IPVD. The first titanium nitride film 23 deposited thereon is excellent in the <111> orientation because of its excellent orientation and flatness. An aluminum film 24 is deposited on the first titanium nitride film 23 and then a second titanium film 25 and a second titanium nitride film 26 are deposited on the aluminum film 24. At this time, the aluminum film 24 is deposited using physical vapor deposition (PVD) or chemical vapor deposition (CVD).

FIG. 2 is a flowchart of a method of forming a nano multi-layer coating layer in Laid-Open Patent Application No. 2013-0060544 (hereinafter referred to as "Prior Art 2"). As shown in FIG. 2, the method for forming a nano multi-layer coating layer according to Prior Art 2 is a method for forming a coating layer using a sputtering mechanism and an arc ion plating mechanism, and a Mo coating layer is formed on a base material by using a Mo target of a sputtering mechanism and Ar gas (S100); A nitriding step (S200) of forming an atmosphere for forming a nitride thin film by using an Ar gas and an N2 gas of an arc ion plating mechanism; A second coating step (S300) of forming a Cr-Mo-N nanocomposite coating layer by simultaneously using an Mo target of a sputtering mechanism, an Ar gas, an Ar gas of an arc ion plating mechanism, an N 2 gas, and a Cr source; And a multi-coating step (S400) in which the nanocomposite coating layer of Cr-Mo-N and the Mo coating layer are repeatedly coated with a multilayer by revolving the base material about the rotation axis (S400).

However, the nano multilayer manufacturing technique using the nano multilayer coating layer forming method according to the prior art 1 and the nano multilayer coating layer forming method according to the prior art 2 can be performed by using a technique with a relatively high process cost such as evaporation, CVD, sputtering and ion plating ALD And a chemical wet method such as a sol-gel method in which the thickness is difficult to control.

KR 0560296 B1 KR 2013-0060544 A

It is an object of the present invention to provide a method of manufacturing a metal layer by electroplating or electroless plating in which metal layers of different kinds are alternately layered in a layer of a nanometer scale, Temperature bonding method using a multi-layered plated film having a lower oxidation rate than that of a nano powder because it is not directly in contact with the atmosphere because it is plated in a plating solution.

Another object of the present invention is to provide a method for bonding a material to be bonded using a multilayer plated film which can be bonded by using a flux in the air in addition to a vacuum state at the time of low temperature bonding of the material to be bonded.

It is still another object of the present invention to provide a multilayered nano-plated layer produced by a plating method using a difference in reduction potential of a metal salt and using pulses as a bonding agent, and the composition, thickness, And a low temperature bonding method using a multilayered plating film capable of bonding at a low temperature by controlling the temperature of the bonding material.

Another object of the present invention is to provide a solder paste which is difficult to be applied by applying to curved or vertical surfaces of the material to be bonded, and can be applied without being restricted to a curved surface or a vertical surface by using a nanometer-scale multilayer plating film, Temperature bonding method using a multi-layered plating film which can be handled independently of the material to be bonded and used as a low-temperature bonding material when the multi-layered plating film is peeled off and used as a foil type.

In order to achieve the above object, the present invention provides a method for bonding a material to be bonded using a multi-layered plated film, comprising the steps of: A low temperature bonding method using a multi-layered plating film for low temperature bonding.

The method for bonding a material to be bonded according to the present invention comprises the steps of: forming a multilayer plating film on a bonding surface of a first bonding material or a bonding surface of a first and second bonding materials; Contacting a plated surface of the multilayered plated film with a multilayered plated film formed on a bonding surface of the second bonding material or a bonding surface of the first and second bonding materials; Heating the first and second materials to be bonded at a low temperature; And an exothermic reaction occurs by mutual reaction of the multi-layered plating films and bonding at a low temperature.

In addition, in the present invention, the bonding at a low temperature is performed in a vacuum, an inert gas, or a reducing gas atmosphere, which is an atmosphere that does not cause oxidation of the bonding surface, and may be performed using a flux in the air.

The multi-layered plating film of the present invention may be formed of any one of Sn (tin), Cu (copper), Zn (zinc), Ni (nickel), Ti (titanium), V (vanadium) (Fe), Co (cobalt), Ga (gallium), Ge (germanium), As (arsenic), Al ), Te (tellurium), Hf (ruthenium), Rh (rhodium), Pd (palladium), Ag (silver), Cd Hafnium), Ta (tantalum), W (tungsten), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Au (gold), Tl (thallium) Bismuth), and a Po (polonium) element.

In addition, the multi-layered plating film of the present invention may have two or more different metal layers stacked thereon.

In addition, the form of the bonding medium in the present invention may be in the form of a plate, a sheet, a foil, a multi-layered plated film, a paste, a bulk or a double- A plating layer is formed on the entire surface of the base material, and the plating material is used as a bonding medium, or a metal ball or a metal-coated non-metallic ball.

Further, the material to be bonded in the present invention may include at least one of metal, ceramics and a polymer material.

The low-temperature bonding in the present invention may be conducted at a temperature not higher than the liquidus temperature of the average composition of the bonding material or the alloy constituting the bonding medium.

In addition, the multilayer plating film in the present invention may be formed in a thickness ranging from 1 nm to 1 mm or less for each layer alternately plated in a multilayer.

According to the present invention, a bonding material using a multilayered plating film as a bonding medium can be bonded in a vacuum in a vacuum state, an inert gas, a reducing gas atmosphere, or in the atmosphere using a flux. And various metals such as copper, tin, zinc, and nickel) can be plated and used as a bonding material, so that the cost of the nanocomposite material is much lower than that of the nano powder. Conventional nano powders are noble metal powders such as gold and silver which are easily oxidized because they are easy to oxidize because of their large contact area with oxygen in the atmosphere.

On the other hand, unlike the nano powder, the present invention has the effect of not oxidizing the noble metal because it is layered in the plating bath in the plating bath (the outermost layer does not form only a natural oxide film in the atmosphere).

In addition, unlike the conventional nano powder having a risk of explosion or fire due to rapid oxidation and heat generation of the nano powder, the multilayered plating film is easy to handle and has a safe effect.

In addition, the present invention can be easily mass produced by a plating method, unlike the conventional method in which multilayer lamination is performed by physical vapor deposition (PVD) or chemical vapor deposition (CVD) such as sputtering in vacuum It is effective.

Further, in the present invention, if a roll-shaped plating electrode is used, the multi-layered plated film can be peeled off and can be manufactured as independent independent foil-type bonding material, and the productivity of thin plate production is increased.

Further, the present invention has an effect that the thickness of the multilayered plating film can be arbitrarily adjusted by controlling the pulse and the plating time.

In addition, the present invention can significantly reduce the junction temperature compared to the conventional bonding method, thereby greatly reducing the energy price (for example, the Sn-3.5 wt% Ag used in the electronics industry has a melting point of about 221 캜, The bonding material is bonded at 250 DEG C. On the other hand, when a multilayer plating film in which Sn and Ag are alternately stacked is used, the bonded material to be bonded can be bonded at a temperature of about 160 DEG C or less).

In addition, in the present invention, the nanometer-scale powder has a melting point lower than that of one kind of metal, so that it is possible to alternately form layers of different kinds of metal layers at a nanometer scale level have.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus for producing an insulating film using a dual organosiloxane precursor compound according to Prior Art 1. FIG.
FIG. 2 is a schematic view of an apparatus for producing an insulating film using the double organosiloxane precursor compound according to the prior art 2. FIG.
3 is a block diagram showing a method of bonding a material to be bonded using a multilayer plating film according to the present invention.
4 is a schematic view showing a method of bonding a multilayer nano-plated surface of first and second materials to be bonded to a surface of another material to be bonded at a low temperature in a method of bonding a material to be bonded using a multilayer plating film according to the present invention.
5 is a schematic view showing an example of a low-temperature bonded specimen in the case where a multilayer plating film is alternately formed of Sn and Cu on the surfaces of the first and second materials to be bonded (copper) in the method of bonding the materials to be bonded using the multilayer plating film of the present invention to be.
6 is a photograph showing an example in which Sn-Cu is alternately nano-multilayered on the surface of the first and second bonding materials before bonding in the method of bonding a bonding material using a multilayer plating film of the present invention.
FIG. 7 is a graph showing the results of a DSC (differential scanning calorimetry) test of a Sn-Cu nano-multilayer plated film in the method of bonding a material to be bonded using a multilayered plating film of the present invention.
FIG. 8 is a photograph showing a state in which Sn and Ag multi-layered plated films are formed only on one test piece and then the test pieces are joined to each other at a low temperature (partially bonded) in the low temperature bonding method using a multilayer plating film according to the first embodiment of the present invention.
FIG. 9 is a photograph showing a state in which Sn and Ag multi-layered plating films are formed only on one test piece and then bonded to another test piece at 160.degree. C. in the low-temperature bonding method using the multilayer plating film according to the first embodiment of the present invention.
10 is a photograph showing a state in which a multilayered plated film is formed on the surfaces of both specimens of the first and second materials to be bonded in the method of bonding the material to be bonded using the multilayered plated film according to the second embodiment of the present invention to be.
11 is a photograph showing a state in which copper is bonded at 160 ° C in a method of bonding a material to be bonded using a multilayer plating film according to a second embodiment of the present invention.
12 is a photograph showing a state after the copper projection electrode is bonded at 160 ° C in a method of bonding a material to be bonded using a multilayer plating film according to a third embodiment of the present invention.
13 is a low temperature bonding state at 160 ° C between a Sn-3% Ag-0.5% Cu solder ball and a nano-multilayered copper substrate in a bonding method using a multilayer plating film according to a fourth embodiment of the present invention It is a photograph.
14 is a photograph showing a copper substrate on which a nano multilayered plated film of Sn and Cu is formed in the method of bonding a material to be bonded using a multilayered plating film according to a fourth embodiment of the present invention.
Fig. 15 is an enlarged photograph of Fig.
FIG. 16 is a graph showing the results of XRD measurement as it is plated before heat treatment of a multilayer plating film (thickness of each of Sn and Cu is 20 nm) in the method of bonding a material to be bonded using the multilayer plating film of the present invention.
17 is a graph showing XRD measurement results of a multilayer plated film (thicknesses of Sn and Cu each having a thickness of 20 nm) after heat treatment at 300 캜 in the method of bonding a material to be bonded using the multilayered plating film of the present invention.
FIG. 18 is a graph showing the results obtained by plating a nano multilayered surface (the thicknesses of Sn and Cu each having a thickness of 20 nm and the total thickness of a multilayer film: 3 .mu.m) only on one side of copper as a bonding material in the bonding method using the multilayered plating film of the present invention, And heated at 160 ° C on a hot plate using a flux.

The terms or words used in the present specification and claims are intended to mean that the inventive concept of the present invention is in accordance with the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain its invention in the best way Should be interpreted as a concept.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to fully inform the category.

FIG. 3 is a block diagram showing a method of bonding a material to be bonded using a multilayered plating film according to the present invention. FIG. 4 is a cross-sectional view showing a method of bonding a material to be bonded using a multilayered plating film according to the present invention. 5 is a schematic view showing a method of joining the plated surface to the surface of another bonding material at a low temperature. Fig. 5 shows a method of bonding the surface of the first and second bonding materials (copper) using a multi- And Cu are alternately formed on the surface of the first bonding material and the second bonding material before the bonding in the method for bonding a bonding material using the multilayered plating film of the present invention. Sn-Cu are alternately nano-multilayer plated, and FIG. 7 is a cross-sectional view showing a method of bonding a thin film of S The n-Cu nano-multilayer plated films were tested by DSC (Differential Scanning Calorimetry) as a graph.

According to these drawings, the bonding material low-temperature bonding method using the multilayered plating film of the present invention is a method of bonding a metal composed of a nano-type multilayer plating film 220, which is formed by alternately plating two or more kinds of elements or alloys thereof, The first and second bonded materials 200 and 210 opposed to each other are bonded together at a low temperature.

That is, in the method of bonding a material to be bonded using the multilayered plating film of the present invention, a multilayered plated film forming step (S100a) or a multilayered plated film forming step (S100b) is performed on the bonding surface of the first to- A pre-treatment step (S110a, S110b), a multi-layered plating film contacting step (S120b) formed on the bonding face of the second bonding material to the plating face of the multilayered plating film or a bonding face of the first and second bonding materials, (S130), and a low-temperature bonding step (S140).

The multi-layered plating film forming step (S100a) or the multi-layered plating film forming step (S100b) on the bonding surfaces of the first and second bonded materials on the bonding surfaces of the first materials to be bonded may include first and second bonding materials A multilayer plating film is formed on the bonding surface of the first bonding material 200 or the bonding surfaces of the first and second bonding materials 200 and 210. [

Here, the first and second materials 200 and 210 are solid bodies in the form of a metal, a ceramic, a polymer material, or the like.

Particularly, in the process of forming the multi-layered plating film (S100a) on the bonding surface of the first material to be bonded or the multi-layered plating film formation step (S100b) on the bonding surfaces of the first and second materials to be bonded, ) Sn-Cu multi-layered plated film and Sn-Ag plated multi-layered plated film were used as the bonding medium. The thicknesses of Sn and Cu of the multi-layered plated film formed by alternately forming the Sn-Cu used in the embodiment of the present invention are 20 nm, and the thicknesses of the Sn and Ag nano-plated layers are respectively 150 nm. The Cu substrate and the Sn-Cu nano-plated film used in the examples are merely illustrative and can be used as multi-layered plated films by using various various elements for bonding various metals and alloys such as iron-based and aluminum-based ones.

* Configurations for manufacturing nanometer-scale multi-layered plated films require plating solutions, metal salts, additives, electrodes, conductive substrates, power supplies with adjustable voltage and current waveforms, and waveform control programs.

In addition, the constitution for bonding using a multilayered plated film as a bonding medium includes a bonding material, a bonding material alternately plated with a nanometer-scale plated film, a foil with alternately stacked nanometer-level metal layers, a heating device for bonding, In some cases, it is necessary to use a vacuum heating device, a cleaning solution for cleaning the surface of the nano-plated layer, and a flux for removing oxides at the time of bonding.

The preprocessing steps S110a and S110b may be performed after the multi-layered plating film forming step S100a is performed on the bonding surface of the first material to be bonded or the multi-layered plating film forming step S100b is performed on the bonding surfaces of the first and second materials to be bonded It is a preprocessing process step.

In this case, the surface of the multilayered plating film 220 is washed with a diluted acid solution such as 5 vol% aqueous hydrochloric acid solution for about 1 minute in order to remove surface contaminants or oxides of the multilayered plating film 220, And rinses again. Where the aqueous acid solution removes the metal oxide, which further facilitates bonding. If the first and second bonded materials 200 and 210 are to be bonded together in the atmosphere, a flux acting at a low temperature may be used to remove the oxide layer on the surface of the multilayered plating film 220.

The step of contacting the bonding surface of the second bonding material to the plated surface of the multilayered plated film (S120a) or the step of contacting the multilayered plated film formed on the bonding surfaces of the first and second bonded materials may be performed on the plated surface of the multilayered plated film 220 Layered plating film 220 formed on the bonding surface of the second bonding material 210 or on the bonding surface of the second bonding material 210. [

At this time, the multilayer plating film 220 in the above step is formed by alternately plating each of the multilayered plating layers 220 to a thickness of 1 nm to 1 mm, and is formed of Sn (tin), Cu (copper), Zn (zinc) (Iron), Co (cobalt), Ga (gallium), Ge (germanium), As (arsenic), Al (Aluminum), Se (selenium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Tc (technetium), ruthenium, rhodium, palladium, (Tin), Re (rhenium), Os (osmium), Ir (iridium), Ta (tantalum) , Pt (platinum), Au (gold), Tl (thallium), Pb (lead), Bi (bismuth), and Po (polonium). Furthermore, the multi-layered plating film 220 may be formed by stacking two or more different metal layers as described above.

On the other hand, it is not necessary to necessarily use the plating on the surfaces of the first and second materials 200 and 210 for bonding, and a bonding medium composed of the multilayer plating film 220 having a thickness of nanometers is separated to form a first foil And the second material to be bonded (200, 210).

Here, the multi-layered plated film 220 refers to a structure in which two or more types of metal layers having a nanometer-scale thickness are stacked in a regular order in the form of a plate having a wide surface shape. When the interlayer material layer is formed, the characteristics are different from those of the alloy. Such a plating layer is in a state of unstable due to a large surface area in contact with dissimilar materials and a high surface energy. Because of this, diffusion can easily occur even with a little heating, and heat is generated in this process. In addition, metals tend to become amorphous (amorphous) in the nanometer-scale plating layer. Since the amorphous is unstable, the metal crystallizes and exothermates even if heated slightly from the outside. The multi-layered plated film 220 can form an alloy in the process of interdiffusion upon heating. The multilayered plating film 220 can be bonded even if the bonding process performed at a conventional high temperature is heated to a low temperature by an external heating apparatus. Due to such characteristics, the multilayered plating film 220 is soldered And brazing can be substituted by a brazing filler metal.

Further, the form of the bonding medium may be formed by forming a plating layer on both surfaces of the member to be bonded, a sheet, a foil, a multi-layer plated film, a paste, a bulk or a metal plate Metal ball or a metal-coated non-metallic ball, all of which are used as a bonding medium.

The first and second bonding material low temperature heating step S130 is a step of heating the first and second bonding materials 200 and 210 at a low temperature and heating the multilayer plating film 220 to the first and second bonding materials 200 , 210, and then brought into contact with each other. 13 shows an example of low-temperature bonding of a solder ball and a plate material on which a nano multilayer film is plated only by its own weight without a fixing device. It can be fixed using a simple fixing device (not shown in the figure) as needed, for example, when the accuracy of the bonding position is greatly required. This prevents the first and second bonding materials 200 and 210 from moving while bonding and allows the multilayer plating film 220 and the first and second bonding materials 200 and 210 to contact each other well.

Further, the first and second bonding materials are subjected to the low-temperature heating step (S130) in a vacuum atmosphere in order to suppress oxide film formation on the surface of the first and second bonding materials 200 and 210. The heating temperature was set to the temperature at which the exothermic reaction was terminated using DSC (differential scanning calorimetry). In the case of a material which does not generate a surface oxidation layer without using a vacuum furnace, or when a flux usable at a bonding temperature is used, bonding in the atmosphere is possible. At this time, the low temperature bonding of the material to be bonded can be carried out in a vacuum, an inert gas reducing gas atmosphere, or the like atmosphere which does not cause oxidation of the bonding surface, and is performed using a flux in the air.

At this time, when the multi-layered plated film 220 is used as a bonding medium, the nanometer-level plated layer is activated as the temperature increases, and the bonding occurs. The principle of activating the multi-layered plated film at low temperature, Is as follows.

First, the multi-layered plated film is liable to decrease the surface energy due to the increase of the surface area due to the decrease of the thickness, and is very unstable. Further, it is intended that the reaction proceeds in a direction in which the interlayer interface of the multilayered plated film exists and the interface energy decreases.

Secondly, as the interlayer spacing between the different materials becomes shorter due to the diffusion, the diffusion distance becomes shorter and the concentration gradient due to the diffusion becomes shorter, so that the diffusion is actively activated and the bonding of the first and second materials to be bonded is activated. It can be seen that the diffusion flux (Flux) is inversely proportional to the distance through the diffusion 1 rule of the following equation (Fick's).

J: Flux representing the number of atoms passing through the unit area per unit time

DB: diffusion coefficient of B atom

C: Concentration

x: spreading distance

dC / dx: concentration change rate in the x direction

Here diffusion refers to the phenomenon that a constituent particle moves from a high chemical potential to a low chemical potential due to a chemical potential difference. In most cases, the chemical potential is proportional to the concentration. That is, in most cases, diffusion occurs from a high concentration to a low concentration. When alternating layers of nanometer-thick plated layers are alternately laminated, the difference in concentration between the different metals is very large (almost 100: 0 between the pure metals), so diffusion by the difference in concentration is easy, Diffusion is active.

Third, the multi-layered plated film is unstable and an exothermic reaction occurs during heating. It is considered that the partial melting of the plating layer occurs due to the heat generated at this time and the bonding occurs.

In the examples, a nanometer-scale multilayer plating film of Sn and Cu each having a thickness of 20 nm was analyzed using DSC. 7, an exothermic reaction occurs within a range of 137 ° C to 183 ° C, and a calorie corresponding to a curve peak area is generated.

In the case of a multi-layered plated film, the thickness of each layer is several tens of nanometers, and the long distance (regular arrangement) of the atoms is present, and the arrangement distance of the atoms is short, resulting in an amorphous characteristic (see FIG. In FIG. 16, the intensity of the Sn-Cu nano-multilayer plated film having a thickness of 20 nm in each layer was measured at a low XRD peak before heat treatment and a back ground was observed. From this, it can be seen that the amorphous phase was contained in the multi-layered nano-plated layer before annealing, that is, Sn and Cu each having a thickness of 20 nm. On the other hand, FIG. 17 shows that Cu, Cu ₆ Sn ₅ , and Cu ₃ Sn peaks were clearly observed after XRD analysis after thermal dehydration at 300 ° C. Based on this, it can be seen that a crystalline plated film is formed. Therefore, it can be seen that the multilayered plated film changes from amorphous to crystalline by heating.

In the low-temperature bonding step S140, an exothermic reaction occurs due to the mutual reaction of the multilayered plating films 220 and is bonded at a low temperature. The first and second bonded materials 200 and 210 and the multi- A diffusion bonding layer 230 is formed on the contact region. That is, in the low-temperature bonding step (S140), the multi-layered plating films are diffused to the surfaces of the first and second bonding materials (200, 210) and bonded to each other. At this time, it is preferable that the low-temperature bonding step (S140) is performed at a temperature of 0.5% to 80% of the liquidus temperature of the average composition of the alloy constituting the first and second materials 200 and 210 or the bonding medium Do.

That is, copper, which is widely used in the electronic packaging industry, is used as the first and second bonding materials 200 and 210 during the low-temperature bonding step S140, and the shape of the first and second bonding materials 200 and 210 Are implemented in the form of a plate or a bump or pillar.

In order to confirm the low-temperature bonding property in the case where the multilayer plating film 220 is alternately formed of Sn and Cu on the surfaces of the first and second materials to be bonded (copper), a multilayer plating film of Sn and / Cu each had a thickness of 20 nm, and the total thickness of the multilayered plated films was 150 m, respectively, to form a nano-multilayered plated film.

Next, an experiment was conducted in which the multilayered plated film 220 was formed only on the surface of the first material to be bonded 200 and the low temperature bonding was observed without forming a multilayered plating film on the other second material to be bonded 210 4). In order to confirm that a metal other than the Sn-Cu plating layer can be used as the bonding material, the multilayer plating film 220 was plated with Sn and Ag to a total thickness of 4 μm on one copper plate as the first bonding material. At this time, the thickness of each of the alternately plated Sn and Ag plated layers was 150 nm. The Sn-Ag layer was contacted with the nano-plated copper material to be bonded and the unplated copper plate, and then heated and bonded in vacuum.

In the present invention, when the material to be bonded is flat, it can be bonded using the own weight of the material to be bonded, but sometimes it can be fixed with a jig for contact between the materials to be bonded. In the present invention, self-weight is used in the case of the ball joint, and a clip is used in the fixing jig in the case of joining the plate material.

In the embodiment, a vacuum furnace was used as a heating device for activating the nano layer for bonding. When the Sn-Cu multilayered film was heated using DSC (Differential Scanning Calorimetry) to confirm the temperature at which the nano layer was activated, The exothermic peak of the exothermic reaction was measured, and the temperature at which the section was terminated was determined to be about 160 ° C as the junction temperature. (See Fig. 7)

&Lt; Example 1 >

▷ After Sn and Ag nano-multilayer plating films are formed on only one specimen of the bonding material,

FIG. 8 is a graph showing the results of a low-temperature bonding method using a multilayer plating film according to the first embodiment of the present invention, in which Sn and Ag multi-layered plating films are formed only on one test piece, 9 shows a method of bonding a material to be bonded using a multilayered plating film according to the first embodiment of the present invention in which a Sn and Ag multi-layered plating film is formed only on one of the specimens, After forming, the other specimens are shown at 160 ° C (complete joint).

The present embodiment is a single cell type in which a multilayer plating film is formed on one specimen of the first member to be bonded and then the second member to be bonded is brought into contact with the first and second members to be bonded. And then bonded at 160 ° C using a vacuum furnace. The cross section of the bonded first bonded member was polished and the bonded portion was observed with an optical microscope (see FIG. 8). The presence or absence of bonding can be determined by the presence or absence of a diffusion layer around the bonding portion in Fig. In Figure 8, some unbonded portions are presented to show the unplated portion of the first bond material copper.

The Sn and Ag multi-layered plating films are formed only on one specimen of the first bonding target to be bonded and the specimen of the other second bonding target material can be bonded at a low temperature as shown in Fig. 8 without forming a multilayer plating film. That is, it is not necessary to perform plating on both sides of the first and second materials to be bonded, and it is possible to join even if only one specimen is plated.

&Lt; Example 2 >

▷ After forming a nano multilayered plating film on the surface of both specimens of the bonding material,

10 is a view showing a state in which a multilayered plated film is formed on the surfaces of both specimens of the first and second materials to be bonded in the method of bonding a material to be bonded using a multilayered plated film according to the second embodiment of the present invention (a Sn-Cu nano- 11 shows the state after the completion of the bonding at 160 ° C in the method of bonding the material to be bonded using the multilayered plating film according to the second embodiment of the present invention (the case where Sn and the Cu nano-multilayer plating film Used) is shown in the photograph.

10 is a dual-cell type embodiment in which a multilayered plated film is formed on both surfaces of both the first and second bonded materials, and the thicknesses of Cu and Sn are multilayer plated to 20 nm, respectively. This was bonded at 200 ° C using a vacuum furnace, and the cross-section of the joint can be seen in FIG.

11 is a specimen prepared under the same conditions as in Fig. 10, but the junction temperature is 160 캜. Among the alloys of Sn and Cu, the melting point is the lowest in Sn-0.7 wt% Cu, which is the process composition, and the melting point is about 227 ° C (this is called the process temperature eutectic temperature). Therefore, it can be seen that the junction temperature of 160 占 폚 using Sn and the Cu-plated multilayered film of this embodiment is significantly lower than the Sn and Cu process temperatures (eutectic temperature).

&Lt; Example 3 >

▷ Cu and Sn multilayer plating films were formed on Cu bump or pillar electrodes, and low temperature bonding

12 is a view showing a state after the completion of the bonding of the copper projection electrode at 160 DEG C in the method of bonding the bonding material using the multilayer plating film according to the third embodiment of the present invention (the Sn and Cu nano-multilayer plating films are plated only on the lower copper) This picture is shown.

Cu protruding electrode-Cu In order to join the protruding electrodes, a Cu-Sn nano-multilayer plating film having a total thickness of about 1 袖 m was formed by alternately forming Cu and Sn on the lower Cu projections by about 20 nm alternately. Then, the two Cu projection electrodes were brought into contact with each other, followed by bonding at 160 ° C using a vacuum furnace. After the bonding, it was confirmed through the cross-section observation that the bonding was completed well (see FIG. 12). Conventional bonding methods include thermosonic bonding using ultrasonic bonding, thermocompression bonding using heat and compressive force, coating of solder on a protruding electrode (solder capped pillar or bump), melting the solder to bond (reflow soldering) method was used. On the other hand, since various metal electrodes such as Ni and Au are used in addition to the Cu projecting electrodes, this embodiment is also useful for these joining.

It goes without saying that the present embodiment can be applied to bonding between bump electrodes in addition to bump or pillar bonding.

<Example 4>

▷ Bonding between solder balls and nano multilayered copper substrate

FIG. 13 shows a state (Sn (3)) in which the Sn-3% Ag-0.5% Cu solder balls and the nano-multi-layered copper substrate are bonded at 160 ° C. in a low temperature bonding method using a multilayer plating film according to a fourth embodiment of the present invention And a Cu nano-multilayer plating film) are shown in Fig. 14. In Fig. 14, a copper substrate having a nano-multilayered plating film of Sn and Cu in a bonding method using a multilayer plating film according to the fourth embodiment of the present invention, And FIG. 15 shows an enlarged photograph of FIG.

In order to bond between Sn-3% Ag-0.5% Cu solder balls and multi-layered copper substrates with nanometer scale, Cu and Sn were alternately multilayer plated on a copper substrate by 20 nm each (total thickness of multilayer film about 2 μm). The solder balls were placed on a plated copper substrate and bonded at 160 캜 using a vacuum furnace. As a result, as shown in FIG. 13, the cross section of the joint was examined by a scanning electron microscope (SEM), and it was confirmed that the joint was satisfactorily bonded. In general, the melting range of Sn-3% Ag-0.5% Cu solder is 217 to 219 ° C, and this solder ball is mostly bonded at about 240 to 260 ° C. Respectively.

FIG. 14 shows an example in which nano-plated films of Cu and Sn are alternately formed on the substrate, and the nano-multilayer plating is performed with a total thickness of about 2 μm.

Fig. 15 shows an enlarged portion of Fig. The reaction layer was observed between the copper substrate and the solder balls, indicating that complete intermetallic bonding occurred despite the low temperature bonding at 160 ° C.

&Lt; Example 5 >

▷ Nano multilayer plating only on one side of copper in air and bonding with copper substrate

Fig. 18 is a graph showing the results obtained by plating a nano multi-layered surface on one side of a copper material to be bonded (each of Sn and Cu having a thickness of 20 nm and a total thickness of a multilayer film: 3 m), using a soldering flux in a hot plate ) At 160 DEG C and bonded to the copper substrate. It can be confirmed that the bonding surfaces are well bonded without defects.

Therefore, the bonding method of the bonding material using the multilayer plating film according to the present invention has the following usefulness.

Conventional brazing and soldering techniques have been used for joining by heating above the melting point of the brazing material (bonding medium). For example, when a Sn-Ag based alloy is used for bonding copper by soldering, the Sn-Ag based alloy having the lowest melting point is Sn-3.5% Ag, which is a process composition, and has a melting point of 221 ° C. Lt; RTI ID = 0.0 &gt; 30 C &lt; / RTI &gt; As another example, when stainless steel is brazed to copper brazing material, the bonding temperature is 1083 ° C or higher, which is the melting point of copper, and the normal brazing bonding temperature is about 1115 ° C or higher.

On the other hand, the present invention uses alternating lamination of Sn and Ag nanometer-scale metal thin films as a bonding medium, and at 160 ° C or less (as the multilayer plating film is thinner, it can be bonded at a lower temperature) It is possible to join. These advantages are similar to those obtained by plating the metals other than Sn and Ag with a nano-type plating layer alternately. The reason for this is that when the nano-shaped plating layers are heated as described above, an exothermic reaction occurs in the diffusion process due to mutual concentration differences and is bonded.

Therefore, when the Sn-Ag system is used as the bonding medium, the conventional soldering method can bond at a bonding temperature of 250 ° C, and 160 ° C of the present invention at a low temperature of about 90 ° C by using the multilayer plating film of the present invention. The lowest temperature among the temperatures at which the Sn-Ag alloy system starts melting is the eutectic temperature (Sn-3.5% Ag) 221 ° C. When the multi-layered plating film is used, the bonding temperature 160 ° C is about 72 %to be. In addition, it is about 64% of the soldering joint temperature of 250 캜 of the conventional Sn-Ag alloy system. In the case of the Sn-Cu alloy system, the lowest melting temperature is 227 ° C. at the eutectic temperature (Sn-0.7% Cu). When the Sn-Cu multi-layered plating film is used, the bonding temperature 160 ° C. is about 70% of the melting point .

Therefore, the consumed energy due to the junction temperature of the present invention is only about 64% of the conventional junction temperature, which is very economical. When the multilayered plating film used in the present invention is thinner, bonding can be performed even at a lower temperature.

This can reduce the cost of consumed energy, prevent thermal damage to electronic components, reduce the strength of the soldered parts due to high temperature heating [strength degradation due to grain growth], inhibit deterioration and grow intermetallic compounds due to high temperature heating have.

This low-temperature bonding phenomenon can be obtained not only in the Sn-Ag system but also in most noble metal multi-layered plating films such as Sn-Cu, Cu-Zn, and Al-Ni.

Further, the present invention can be applied to a field where various joining such as conventional brazing, soldering, soft soldering, diffusion bonding, etc. is applied, and can be bonded by heating at a temperature lower than the conventional temperature. Specific examples of the application of the solder bumps include solder bumps, bump and bumpless solder balls, solder balls, solder bumps, solder bumps, Foil, solder wire, plated brazing material and related bonding materials, and microelectromechanical systems (MEMS). It can be applied to various kinds of heat exchangers such as radiators, condensers, oil coolers, and instantaneous water heaters which are applicable to brazing materials (thin plate, wire, ball, plating, etc.) for brazing, It can be applied to automotive, aerospace, machinery parts and other industrial parts, brazing, soldering and bonding of equipment.

In addition to Sn-Ag, Sn-Cu is alternately plated with a nanometer scale, and the present invention is similarly bonded at a temperature of 160 ° C or lower. Conventional techniques for bonding copper electrode pores in silicon wafers commonly used in the electronics industry are to bond the copper wires together by thermocompression bonding or to bond the solder to the copper protrusions at a temperature of 240 to 250 ° C. However, when using the present invention, a nano-plated layer alternately stacking Sn and Ag or a nano-plated layer alternately stacking Sn and Cu is bonded at a temperature of 160 ° C or lower. Of course, similar results can be obtained by using a nano multilayer plating film of a metal other than Sn and Ag, Sn and Cu layers.

Even when there is no projection electrode in the bumpless bonding, bonding can be performed at a low temperature if the multilayered plating film of the present invention is plated on the surface of the electrode to a thickness of nanometer. Currently, the size of the bumps used in the bonding of the semiconductor silicon chips is several tens of micrometers to several hundreds of micrometers. When the present invention is applied and bonded by bumpless bonding, the thickness of the multilayered plated film can be reduced So that the silicon chip can be stacked three-dimensionally or the thickness of the flip chip can be greatly reduced.

When applied to the thermocompression bonding method, in the electronic industry, various metal projections (electrodes) such as copper-copper, nickel-nickel, and gold-gold on the substrate are bonded at about 180 ° C. by thermocompression bonding. Using the present invention, bonding is possible at 160 ° C or less.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

200, 210: first and second bonded materials
220: multilayer plating film

Claims (9)

A method for bonding a material to be bonded using a multi-layered plating film for bonding a material to be bonded opposite to each other with a metal made of a multilayered plated film alternately plated and stacked with two or more kinds of elements or alloys thereof as a bonding medium.
The bonding method according to claim 1,
Forming a multilayer plating film on the bonding surface of the first bonding material or the bonding surfaces of the first and second bonding materials;
Contacting a plated surface of the multilayered plated film with a multilayered plated film formed on a bonding surface of the second bonding material or a bonding surface of the first and second bonding materials;
Heating the first and second materials to be bonded at a low temperature; And
Wherein the exothermic reaction occurs due to the mutual reaction of the multilayered plating films and is bonded at a low temperature.
3. The method according to claim 1 or 2,
Wherein the low temperature bonding of the material to be bonded is performed in a vacuum, an inert gas, or a reducing gas atmosphere which is an atmosphere that does not cause oxidation of the bonding surface, and is carried out using a flux in the air.
3. The method according to claim 1 or 2,
The multilayered plating film may be formed of at least one of Sn (tin), Cu (copper), Zn (zinc), Ni (nickel), Ti (titanium), V (vanadium), Cr (Cobalt), Ga (gallium), Ge (germanium), As (arsenic), Al (aluminum), Se (selenium), Zr (zirconium), Nb (niobium), Mo (molybdenum) , Tantalum), Hf (hafnium), Ta (tantalum), tantalum (tantalum), tantalum (Ta) ), W (tungsten), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Au (gold), Tl (thallium), Pb (lead), Bi (bismuth) ) &Lt; / RTI &gt; element, which is a metal layer containing at least one of the elements.
5. The method of claim 4,
Wherein the multilayer plating film is a multilayer plating film in which two or more different metal layers are stacked.
The method according to claim 1,
The form of the bonding medium may be a form of plating on a member to be bonded, a sheet, a foil, a multi-layered plated film, a paste, a bulk or a metal plate, A metal ball or a metal-coated non-metallic ball; and a low-temperature bonding method using the multilayered plating film.
3. The method according to claim 1 or 2,
Wherein the material to be bonded is a solid body to be bonded including at least one of a metal, a ceramic and a polymer material.
3. The method according to claim 1 or 2,
Wherein the low temperature bonding is performed at a temperature not higher than a liquidus temperature of an average composition of the bonding material or an alloy of the bonding medium.
3. The method according to claim 1 or 2,
Wherein the multilayered plated film is formed by alternately plating one multilayered film in a thickness ranging from 1 nm to 1 mm or less.

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