JP3172308B2 - Metal layer for solder connection, electronic component or circuit board having the same, and electronic circuit device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal layer for solder connection, an electronic component or a circuit board having the same, and an electronic circuit device using the same. The present invention relates to a metal layer for solder connection that facilitates replacement of electronic components while maintaining a good solder connection, an electronic component or a circuit board having the same, and an electronic circuit device using the same.

[0002]

2. Description of the Related Art In an electronic circuit device such as a large-sized electronic computer, a large number of electronic circuit components such as an LSI are mounted on a printed circuit board, a ceramic circuit board, or the like to form an electronic circuit. These typical mounting methods are as follows. First, these circuit boards (hereinafter abbreviated as boards)
Is formed with a metal layer pattern serving as a connection portion for solder connection. On the other hand, metal terminals for electrodes or metal layers for solder connection are formed on electronic circuit components. Thereafter, both are connected using solder.

After mounting electronic circuit components such as LSI on a substrate,
For example, there is a case where the electronic circuit is removed from the board to change the logic of the electronic circuit, replaced with a new part, and mounted again (this step is referred to as repair here). In removing the component, the component is removed by heating and re-melting the solder connection part of the electronic circuit component. At this time, a part of the metal layer constituting the connection portion of the board is removed from the board at the same time as the replacement of the parts. The reason for this is that the solder connection is mainly formed by alloying a part of the metal that forms the solder alloy and a part of the metal layer that forms the connection part of the board, and the solder connection is removed by heating and melting. In this case, part or all of the alloy is simultaneously removed. As an example of a commonly used connection system, when the solder is Sn / Pb solder and the metal layer is a Ni layer, the connection is established mainly by forming an Sn-Ni alloy. When the electronic component is removed, part of the alloy is removed at the same time. When a new component is remounted, a new metal layer at the same connection point is consumed for solder connection.

[0004] Repair is indispensable in order to improve the production yield of the electronic circuit device, but the metal layer is consumed by repeated repair and may eventually disappear. In this state, normal connection is not established, so that the reliability of the solder connection part is significantly reduced, or the solder connection itself becomes impossible. Conventionally, in order to prevent this from happening, it has been most common to form a sufficient metallization thickness by plating or the like in advance, which is expected to be consumed in the allowable number of repairs.

On the other hand, in recent years, in order to meet the demands for higher density and miniaturization of electronic parts, a cleaner method for forming a metal film on electronic parts, and higher reliability of connection parts of parts, a sputtering method is used instead of a plating method. There is an increasing demand for forming a solder connection metal layer of about 1 μm or less on a substrate by a physical vapor deposition method such as vapor deposition, ion plating or the like or a chemical vapor deposition method. In this case, increasing the metal film thickness by sputtering or vapor deposition for the purpose of realizing repair many times is as follows:
Since the residual stress of these films is extremely large compared to the residual stress of the film formed by the plating method, it is not appropriate because the residual stress of the formed metal film itself causes cracks, and many repairs are not appropriate. It was difficult. Also,
Generally, as metallization of electronic components, a metal having a low reaction rate to be alloyed with solder, a metal not alloyed with solder, or an alloy having these properties is used as a barrier layer (underlayer) by sputtering or vapor deposition. There is also used a method in which a metal film is formed on a substrate and a metal film which is easily alloyed with solder is formed thereon. However, in this metallized structure, the metal layer directly connected to the solder is a metal film formed on the barrier layer and easily alloyed with the solder, and therefore does not meet the demand for repairing many times.

[0006] Conventional techniques relating to metallization for solder connection include, for example, the 40th E.C.T.S.C. Proceeding, pp.460-469 and 408-411 (1990) [40th. ECTC Proceedings (199
0) PP460-469 "Reliabilityimprovements in solder b
ump processing for flip chip ", pp408-411" Produc
of MCP Chip Carrier ”], JP-A-2-231750, and the like. Among these examples, in the first example, Cu is used as a metal layer for solder connection, and TiW is used as an adhesion layer with a barrier layer and a passivation film.

[0007]

However, of the above-mentioned prior arts, a method of forming a metallized thickness corresponding to the expected number of repairs in advance by plating or the like is to increase the density and miniaturization of electronic parts. It cannot meet the requirement of forming a metal layer for solder connection with a thin film of about 1 micron or less in order to cope with a clean method of forming a metal film of an electronic component and to increase the reliability of a component connection part. In addition, it cannot cope with a large number of repairs exceeding the scheduled number.

Further, a method of applying a metal or an alloy which does not react with solder or a metal or an alloy which does not easily react with solder to a barrier layer and forming a metal thin film which easily alloys with solder is applied to the barrier layer. When it disappears, alloying of the metal of the barrier layer and the solder is unlikely to occur, so that a normal connection cannot be realized after all.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and a first object of the present invention is to provide an improved metal thin film layer for solder connection capable of maintaining good connection even after a large number of repairs. An electronic component or circuit board having the same, a second object is a manufacturing method thereof, a third object is an electronic circuit device in which electronic components are mounted and connected to the circuit board, and a fourth object is an electronic circuit device. Manufacturing method
To provide each.

[0010]

The above objects of the present invention are attained by the following means. First, the first
The object of the present invention is that the metal layer for solder connection is easily wetted with the metal constituting the solder, and the first metal easily alloyed or forms an intermetallic compound, and is not easily wetted and eluted with the solder. This is achieved by a solder connection metal layer composed of a metal layer in which a second metal is mixed as a constituent component, and an electronic component or a circuit board having the same.

The first metal constituting the solder connection metal layer is preferably made of, for example, at least one of Au, Cu, Ni, Ti, Sn and Pt. It is desirable to provide a concentration gradient so that the concentration becomes high.

Further, a preferred combination of the solder component and the metal layer for solder connection will be described in detail. (1) The solder is at least one of Sn-Pb alloy, Sn-Bi alloy, Sn-Pb-Bi alloy and Sn. When comprising, the first metal constituting the metal layer for solder connection is at least one of Au, Cu, Ni, Ti and Pt, and the second metal is at least one of W, Re and Ta. It is desirable to configure.

(2) In addition, the above-mentioned solder is formed of Sn-Ag alloy, Sn-Sb alloy, Sn-In alloy, Pb-In alloy, Pb-Sb alloy, Au-Sn alloy, Au-Ge alloy, Sn-Ag- Sb alloy, Sn-Pb-In alloy, S
n-Pb-Sb alloy, Sn-Pb-Ag alloy, Sn-B
i-In alloy, Pb-Ag-In alloy and Sn-Pb-
When composed of at least one Bi-In alloy,
The first metal constituting the metal layer is Au, Cu, Ni,
At least one of Sn and Ti, wherein the second genus is W,
Desirably, it is composed of at least one of Re and Ta.

(3) When the solder is made of a Pb-Bi alloy, the first metal forming the metal layer is at least one of Au, Ni and Ti, and the second metal is W. , Re, and Ta.

The first metal is Ni and the second metal is W
In the case of comprising, the metal layer for solder connection becomes a Ni-W alloy layer, and the preferable composition ratio of Ni and W is 20%.
at% ≦ Ni <100 at%, 0 <W ≦ 80 at%, and the number of repairs of the solder connection metal layer in this case is 3
Indicates more than one time. Also, more preferable 85 at% ≦ Ni <
When the composition ratio is 100 at% and 0 <W ≦ 15 at%, the number of repairs is 5 or more, more preferably 95 at% ≦
Ni <100 at% and 0 <W ≦ 5 at% for the composition 15
97at%, which indicates a number of repairs of more than 100 times
A composition of ≦ Ni ≦ 99 at%, 1 at% ≦ W ≦ 3 at% shows a repair resistance number of 24 times or more.

(4) Further, the above solder is made of Pb-A
In the case of using a g alloy, it is preferable that the first metal forming the metal layer is formed of at least one of Au, Sn, and Ti, and the second metal is formed of at least one of W, Re, and Ta. .

A second object of the present invention is to provide a solder having a step of selectively forming a solder connection metal layer constituting a connection terminal portion of an electronic component on a predetermined substrate such as an electronic component or a circuit board. In the method for manufacturing a metal layer for connection, the step of forming the metal layer for solder connection includes the steps of: forming a first metal that easily wets with a metal constituting the solder and easily alloys or forms an intermetallic compound; Not easily wet
This is achieved by a method of manufacturing a metal layer for solder connection, which comprises a step of forming a thin film layer by mixing a second metal that does not elute as a constituent component.

Preferably, in the step of forming the metal layer for solder connection, the concentration of the first metal in the metal layer for solder connection is adjusted so as to be high on the surface side of the metal layer for solder connection. This is to form a film with a gradient. The step of forming the thin film layer includes, for example, sputtering, vacuum evaporation, a physical vapor deposition method such as ion plating or a chemical vapor deposition method, and a film formation step including any one of a plating method. At the time of film formation, a mask in which a pattern of a connection portion is formed in advance is placed on or closely adhered to the substrate to selectively laminate the metal layer, or a thin film layer is formed on the substrate without using a mask. After the film is formed, it is preferable to form a predetermined etching mask on the thin film layer and selectively pattern it by lithography to form a connection portion.

The third object is to mount an electronic component such as an LSI on an electronic component or a circuit board which can achieve the first object, and to form a solder on a metal layer for solder connection via a solder. This is achieved by a connected electronic circuit device. The preferred combination of the composition of the solder to be used and the first and second metals constituting the metal layer to be the connection portion of the substrate is as described above.

The fourth object is to prepare an electronic component or a circuit board which can achieve the first object, and place another electronic component on the solder connection metal layer pattern formed on the electronic component or the circuit board. This is achieved by a method for manufacturing an electronic circuit device, comprising a step of positioning and a step of solder-connecting the metal layer and an electronic component by solder reflow. The preferred combination of the composition of the solder to be used and the first and second metals constituting the metal layer to be the connection portion of the substrate is as described above.

[0021]

The operation of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram schematically showing an example of a cross section of a metal thin film layer 20 constituting a solder connection portion formed on a substrate 6 of the present invention. Metal thin film layer 20 according to the present invention
Is formed by a physical vapor deposition method such as sputtering, vacuum deposition, or ion plating, a chemical vapor deposition method, or a plating method. In this manner, the metal constituting the solder component, the first metal 1 (indicated by a black circle in the figure), which easily wets and easily forms an alloy or an intermetallic compound, are formed on the substrate 6 by soldering. And a second metal 2 (indicated by a circle in the figure), which is not easily wetted and eluted, is formed as a main component.

FIG. 2 is a conceptual diagram schematically showing an example of a cross section near the metal thin film layer of the connection portion after the solder has been reflowed on the metal thin film layer 20. Where the solder is
It is composed of a component 3 (indicated by a triangle in the figure) and a component 4 (indicated by a black triangle in the figure).
Easily wets with the first metal 1 constituting the metal thin film layer 20 to form an alloy or an intermetallic compound. In the reflow step, a part of the first metal 1 constituting the metal thin film layer 20 elutes into the molten solder in order to form an intermetallic compound with the component 4 of the solder. At this time, the components 3 and 4 of the solder are replaced with the first metal 1 constituting the eluted metal thin film layer 20. As a result, a solder alloy is formed, and a solder connection is established.

Next, the behavior of the solder connection at the time of repair will be described. First, when the connection portion of the substrate 6 is heated, a part of the first metal 1 constituting the metal thin film layer 20 eluted in the solder and the solder is melted. When the electronic component is removed, a part of the melted portion is removed simultaneously with the component. The remaining portion of the molten alloy remains on the metal thin film layer 20 when the component is removed. Since the second metal 2 constituting the metal thin film layer 20 does not elute in the solder, it remains on the substrate 6 side when components are removed. FIG. 3 schematically illustrates this concept. Remounting of a new component is performed on the remaining metal thin film layer portion. FIG. 4 schematically illustrates this concept.

In subsequent repairs, this phenomenon is repeated. After a number of repairs, the first metal 1 forming the metal thin film layer 20 elutes, and the second metal 2 forming the metal thin film layer 20 is mixed with the replacement of the solder constituent elements. Connection is established. FIG. 5 schematically illustrates this concept.

The first metal 1 which easily wets with the metal constituting the solder and easily alloys or forms an intermetallic compound, and the first metal 1 which does not easily wet and elute with any component of the solder. In the case where the concentration of the first metal 1 in the metal thin film layer 20 including the second metal 2 as a constituent element is mixed in a concentration gradient that increases on the solder connection surface side, for the same reason as described above. , After many repairs,
Normal connection is established. In this case, since the first metal 1 that easily forms an intermetallic compound with solder is dense on the initial soldering surface constituted by the metal thin film layer 20, wettability is particularly good.

Next, as an example, Ni is added to the first metal 1.
The operation when W is applied to the second metal 2 and the Sn—Pb alloy is applied to the solder will be specifically described. Ni as the first metal 1 easily alloys with Sn of the solder component to form an intermetallic compound, and W as the second metal 2
Does not easily wet and elute with any of the solder components Sn and Pb. First, a circuit board 6 made of ceramic or the like
Mixed thin film layer 20 of Ni and W
Is formed by a physical vapor deposition method such as sputtering, vacuum deposition, or ion plating, a chemical vapor deposition method, or a plating method. In the solder reflow process for connecting the electronic components, Ni (first metal 1), which is one of the constituent elements of the Ni / W mixed thin film layer 20, is easily alloyed with Sn in the solder. Elute. This eluted Ni
Forms an intermetallic compound with Sn. Ni eluted at the same time
Is replaced with Sn or Pb. As a result,
A solder connection is established. W (second metal 2) is Sn, P
b does not readily wet and elute.

The behavior near the solder connection interface at the time of repair is as follows. First, at the time of heating the connection part, a part of the solder and the Ni-Sn intermetallic compound are melted. When the electronic component is removed, a part of the molten portion is removed simultaneously with the component. The remainder of the molten alloy is
It remains on the Ni / W metal thin film layer 20 side of the substrate. Remounting of a new component is performed on the remaining metal layer portion.
In subsequent repairs, this phenomenon is repeated. After many repairs, the solder connection is established by the mixture of W and Ni, which are eluted and replaced by Sn or Pb, and W.

Also, in the metal thin film layer 20 in which Ni and W are mixed so as to have a concentration gradient such that the Ni concentration increases on the soldering surface side, the repair is performed many times for the same reason as described above. Even afterwards, a normal connection is established. Also, in this case, the initial soldering side composed of the metal thin film layer 20 is dense with Ni, which easily forms an intermetallic compound with Sn in the solder, so that the wettability is improved.

As described above, Ni and W are typical examples of the metal thin film layer 20, and Sn-Pb is a typical example of the solder.
The operation has been described by taking the case of using an alloy as an example. In addition, Au, Cu, Pt, Sn, and Ti are used for the first metal 1.
The same applies to the case where Re and Ta are used as the second metal 2 and a metal other than Sn-Pb is used as the solder, and the description thereof is omitted.

[0030]

An embodiment of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 6 is a partially cutaway perspective view showing an example of an electronic circuit device of the present invention. A ceramic multi-layer wiring board 8 is used as a circuit board, and a connecting portion of the ceramic multi-layer wiring board 8 includes a first metal that easily wets with at least one metal of a solder component and easily forms an alloy or an intermetallic compound, and a solder component. A metal thin film layer for solder connection is formed by mixing a second metal which does not easily wet and elute with any of the above metals. The ceramic multilayer wiring board 8 has A
An LSI chip 7 having u-plated electrode terminal portions is mounted and connected by micro solder balls 14 composed of 3% by weight of Ag and the balance of Sn. That is, in this electronic circuit device, a plurality of LSI chips 7 are arranged on a multilayer wiring board 8 according to a predetermined arrangement pattern, and a heat conduction relay member 11 is placed on the LSI chips.
And the multilayer wiring board 8 is placed on the relay member 11 from above.
And a cap 10 for covering the cap 1
The cooling plate 9 is laminated on the upper surface of the cooling plate 9. The multilayer wiring board 8 is connected to the wiring board 13 via the connection pins 12 to form an electronic circuit.

Next, a method of manufacturing the electronic circuit device will be described. First, a method for forming a metal thin film layer for solder connection, which is a feature of the present invention, on a ceramic multilayer wiring board 8 will be described. First, a target capable of simultaneously sputtering a plurality of targets, for example, a binary simultaneous ion beam sputtering device, is used as a target with N.sub.99 of 99.999% purity.
An i plate (first metal 1) and a W plate (second metal 2) having a purity of 99.999% are attached to predetermined positions. Next, a ceramic multilayer substrate 8 on which a wiring pattern is formed in advance
Is covered with a stainless steel mask from which a predetermined pattern corresponding to the shape of the connection portion is removed, and is placed at a predetermined position in the sputtering apparatus. Next, Ni and W targets are simultaneously sputtered by Ar ion beam or the like, respectively, and a thin film (90% Ni in atomic percent, 10% W composition) in which Ni and W are uniformly mixed on a ceramic multilayer substrate, Laminate to a thickness of 1 micron. At this time, the ceramic multilayer substrate may be heated to about 100 to 300 ° C. Thus, a metal thin film layer for solder connection having a predetermined pattern shape was selectively formed on the substrate. Note that a connection portion can also be formed by forming a metal thin film layer without using a stainless steel mask and then performing selective etching by lithography using a predetermined mask.

Next, an LSI chip 7 in which a portion to be soldered is plated with Au in advance, a cooling plate 9 and a cap 1
0, the heat conduction relay member 11, the connection pins 12, and the wiring board 13 were prepared. Further, as the solder for assembling the device, a fine solder ball 14 having a composition of 3% by weight of Ag—97% by weight of Sn was used as the first solder, and a composition of 37% by weight of Sn—45% by weight of Pb—18% by weight of Bi was used as the second solder. Alloy 15 as the third solder
A solder alloy 16 having a composition of b 98 wt% -Sn 2 wt% and a silver solder (fourth solder alloy) 17 having a composition of 72 wt% Ag-28 wt% Cu were prepared.

Thereafter, first, the ceramic wiring board 8 is formed.
After heating to 800 ° C. with the above-mentioned silver solder (fourth solder alloy) 17 interposed between the back surface of the substrate and the connection pin 12, a cooling process (hereinafter, simply referred to as a heat treatment) is performed to cool the two. Connecting. Next, the ceramic multilayer wiring board 8
A small solder ball 14 made of a first solder alloy is interposed between the solder thin film layer portion of the present invention and the electrode terminal of the LSI chip 7 on the surface of
The two are connected by performing a heat treatment at 40 ° C.

On the other hand, between the cooling plate 9 and the cap 10,
The two are connected by performing a heat treatment at 340 ° C. with the third solder alloy 16 interposed therebetween. Further, after arranging the heat conducting relay member 11 on the LSI chip 7 connected to the ceramic multilayer wiring board 8, the periphery of the ceramic multilayer wiring board 8 and the cooling plate 9 and cap 10
The two are connected by performing a heat treatment at 200 ° C. with the above-mentioned second solder alloy 15 interposed between the peripheral portion on the side of the cap 10. An electronic circuit device having electronic components mounted and connected on the circuit board of the present invention was manufactured by the above method.

Next, whether the connection method using the metal thin film for solder connection according to this embodiment achieves a normal connection after many repairs, which is a technical problem of the present invention, will be specifically described below. Try to evaluate by method. In order to carry out a repair experiment, in the above-mentioned manufacturing process, the LSI chip 7 is heat-treated at 240 ° C. with the micro solder balls 14 made of the first solder alloy interposed in the ceramic multilayer wiring board 8 to thereby perform the heat treatment at 240 ° C. Create a connected sample.

For comparison, a sample for a repair experiment similar to that described above is prepared for a metal thin film for solder connection formed on a ceramic multilayer wiring board by a conventional method. As a conventional thin metal layer for solder connection,
After r was formed as a base layer (barrier layer) by sputtering to a thickness of 0.2 μm, Ni was formed by sputtering to a thickness of 1 μm to form a thin film layer having a two-layer structure. The Cr in the underlayer does not easily wet the solder or form an intermetallic compound when soldered.

The two samples are repeatedly repaired by the following method, and the solder connection strength of the LSI chip is measured at each repair count. First, a chip repair method will be described. The LSI chip mounted on the ceramic multilayer substrate is heated by using an infrared lamp so that the temperature of the solder connection becomes 240 ° C. to melt the solder connection. In this state, the LSI chip is removed from the substrate by lifting it up. Next, the Cu plate is placed on the substrate at a position corresponding to the removed LSI, and is lifted upward while being heated to 240 ° C. by an infrared lamp to remove a part of the solder remaining on the substrate, Flatten the solder connection. Next, a new LSI chip is connected to the ceramic multilayer wiring board by soldering in the same manner as the method of preparing the sample at first. From now on,
Repeat the repair in the same way.

The solder connection strength of the LSI chip corresponding to each repair count was measured by the following method. First, LS
A hexagonal metal nut is connected to the upper surface of I (non-solder connection surface) with an adhesive. Next, the nut was rotated on the same plane as the LSI chip, and the maximum force generated until all the solder connecting the LSI was broken was measured by a tester. FIG. 7 shows the test results. Than this,
In the connection using the metal thin film layer for solder connection (two-layer structure of Cr / Ni) according to the conventional method, the strength is remarkably reduced when the number of repairs is two or more, and it can be seen that normal connection is not performed. On the other hand, in the connection using the metal thin film layer for solder connection (two kinds of metals Ni and W are uniformly mixed) according to the present invention, the connection strength does not decrease up to five repairs and the number of repairs increases. I have. This confirmed the effectiveness of the present invention.

In this embodiment, Ni is used as the first metal which easily wets with at least one kind of metal of the solder component and easily forms an alloy or an intermetallic compound. Although an example in which W is applied as the second metal that does not easily wet and elute is shown, Au, Cu, Sn, Ti, and Pt are partially or entirely replaced with Ni, and Re is replaced with W. It is needless to say that an electronic circuit device can be produced by the same method when a part or all of Ta is applied and a metal other than Sn-Ag is applied to the solder alloy. The formation of the metal thin film layer for solder connection is not limited to binary simultaneous ion beam sputtering, and may be formed by sputtering a single target in which two types of metals are mixed.

<Embodiment 2> This embodiment is similar to the embodiment 1 described above.
The manufacturing process of the metal thin film layer 20 for solder connection of FIG. That is, in the first embodiment, a thin film layer in which the first metal and the second metal are uniformly mixed is used. However, in the present embodiment, the concentration gradient is increased so that the concentration of the first metal becomes higher on the connection surface side. Is provided. Except for the process of manufacturing the metal thin film layer, the electronic thin film layer was manufactured in exactly the same steps as in Example 1, and an electronic circuit device having the same configuration as that of FIG. 6 was realized. Therefore, here, the method of forming the metal thin film layer 20 for solder connection having a concentration gradient, which is a feature of the present invention, will be mainly described.

First, a target capable of simultaneously sputtering a plurality of targets, for example, a binary simultaneous ion beam sputtering device, is used as a target with N.sub.99 of 99.999% purity.
An i plate (first metal 1) and a W plate (second metal 2) having a purity of 99.999% are attached to predetermined positions. Next, the ceramic multilayer substrate 6 serving as a circuit board is covered with a stainless steel mask from which a predetermined connection pattern has been removed, and is placed at a predetermined position in the sputtering apparatus.

After that, first, a W target is sputtered with a strong intensity by an Ar ion beam or the like, so that W is laminated on the ceramic multilayer substrate 6. At the time when the W film thickness becomes about 0.2 μm, the sputtering intensity of the W target is weakened and removed, and at the same time, the sputtering of the Ni target is started. To occur. When the thickness of the mixed metal film reaches 0.8 μm, the sputtering of the W target is stopped, and only the Ni target is sputtered to reduce the Ni film thickness to 0.2.
Micron.

By the above steps, a mixed film of Ni and W having a thickness of 0.8 μm is formed on W having a thickness of about 0.2 μm (a concentration gradient is formed on the solder connection surface side so that the Ni concentration becomes large). And a 0.2 micron thick layer of N
A metal thin film layer made of i and having a total thickness of 1.2 microns is formed. At this time, the ceramic multilayer substrate 6 is
It may be heated to about ° C. The ceramic multilayer wiring board 8 on which the metal thin film layer for solder connection is formed in this manner is
Components 7 such as SIs are mounted and connected. These steps are the same as those in the first embodiment, and thus description thereof is omitted.

Next, it is determined whether or not the connection method using the metal thin film layer for solder connection according to this embodiment realizes a normal connection after repairing many times, which is a problem of the present invention. An evaluation test was specifically performed in the same manner as in Example 1. FIG. 8 shows the result. In FIG. 8, the metal thin film layer for solder connection used for connection according to the conventional method is formed by forming a 0.2-micron sputter film using Cr as an underlayer (barrier layer) and then forming a 1-micron Ni film.

That is, FIG. 8 shows the relationship between the maximum breaking load and the number of repairs in comparison with the conventional example. In the present embodiment, the connection strength does not decrease even when the number of repairs is 20 times. It can be seen that a normal connection is made. Further, in the case of this embodiment, the mixed film of Ni and W has a concentration gradient on the solder connection surface side so that the Ni concentration becomes large. The wettability is good, the number of repairs is increased, and extremely reliable solder connection is enabled.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments but can be further modified. For example, the metal thin film layer for solder connection of the present invention can be applied to the solder connection portion of the multilayer wiring board 8 and the cap 10 in the electronic circuit device having the configuration shown in FIG. Further, the components of the electronic circuit device are not limited to the example of FIG.

<Embodiment 3> In this embodiment, the configuration of the metal thin film for solder connection of Embodiment 1 and the composition of the solder are changed. W was used for the second metal constituting the metal thin film for solder connection, and the first metal was variously changed. Table 1 shows the composition of the metal thin film, the solder composition and the results of the repair experiment.
Shown in The method of manufacturing the metal thin film for solder connection is described in Example 1.
The composition ratio of the first metal and the second metal (W) was set to 80:20 in atomic percent, and the film thickness was set to 1 micron. For comparison, a conventional thin metal film for solder connection has a two-layer structure in which a 0.2-micron film is formed using Cr as a base (barrier layer), and a 1-micron film is formed on the first metal. Layers.

Table 1 shows that the first metal is A
u, Cu, Ni, Pt, Sn, Ti, W as the second metal, and Sn-Pb, Sn-Bi, Sn- as the solder composition
Pb-Bi, Sn, Sn-Ag, Au-Sn, Au-G
For the combination of e, Pb-Bi, and Pb-Ag, the maximum number of repairs at which the initial connection strength is maintained is shown.
In addition, the upper row in the table is a conventional metal thin film configuration serving as a comparative example,
The lower part shows the configuration of the metal thin film according to the present example.
In any case, the number of repairs is improved by the metal thin film configuration of the present embodiment, and good connection is obtained. However, in the case of using Ti as the first metal, the solderability is inferior to any other metal when using any of the solders.
In order to improve this, it was necessary to take measures such as using a strong flux or setting a higher heat treatment temperature.

[0049]

[Table 1]

<Embodiment 4> In this embodiment, the structure of the metal thin film for solder connection of Embodiment 1 and the composition of the solder are changed. Contrary to Example 3, the first metal was fixed to Ni, and the second metal was variously changed. Table 2 shows the configuration of the metal thin film for solder connection, the composition of the solder, and the results of the repair experiment. The method of manufacturing the metal thin film for solder connection was the same as in Example 1, the composition ratio of the first metal (Ni) and the second metal was 80:20 in atomic percent, and the film thickness was 1 micron. For comparison, a conventional thin metal film for solder connection was a thin film layer having a two-layer structure in which Cr was formed as a base layer (barrier layer) and 0.2 μm was formed thereon, and Ni was formed thereon in a thickness of 1 μm. .

Table 2 shows that the first metal is N
i, W, Re, Ta as the second metal, Sn-Pb, Sn-Bi, Sn-Pb-Bi, Sn, as the solder composition
The combination of Sn-Ag, Au-Sn, Au-Ge, and Pb-Bi indicates the maximum number of repairs at which the initial connection strength is maintained. The upper part of the table shows the structure of a conventional metal thin film as a comparative example, and the lower part shows the structure of the metal thin film according to the present example. In any case, the number of repairs is improved by the metal thin film configuration of the present embodiment, and good connection is obtained.

[0052]

[Table 2]

<Embodiment 5> The electronic circuit device of this embodiment also has the same external appearance as the cross-sectional perspective view of FIG. 6 shown in Embodiment 1, but the first metal constituting the solder connection metal layer. Is an example in which the composition ratio between Ni and Ni is W and the second metal is W, respectively. FIG. 9 is an enlarged sectional view of a portion A in FIG.
An LSI chip 7 having a metal film 33 for solder connection and an Au-plated metallized terminal portion 34 is formed on an electronic circuit board 8 having a thin film circuit formed by the method 1 by using a small solder ball having a composition of 3% by weight of Ag and the balance of Sn. 14 shows a connected state. FIG. 10 is a detailed cross-sectional view enlarging a portion B of FIG. 9 and shows a detailed structure of solder metallization. This metallization is performed on the electronic circuit board 8 on which the thin film circuit is formed by the polyimide insulating layer 30 and the wiring layer 31.
After forming a Ni—W alloy as a solder reaction layer and Au as a wetting ensuring layer on the third layer 33-3, soldering is performed using the solder. However, in this figure, the third layer of Au is shown to be present even after soldering, but this represents the initial state, and after the soldering, Au originally diffuses into the solder 14. And does not exist as metallization.

Next, a method of manufacturing the electronic circuit device will be described. (1) Manufacturing process of electronic circuit board 8: A thin film wiring circuit 8-1 is formed on an insulating substrate 8-2 such as a ceramic substrate by using a wiring layer 31 having a small electric resistance such as Al and Cu and a polyimide insulating layer 30. .

(2) Step of forming metallized layer: Solder metal film terminals 33 are formed on the thin film wiring circuit 8-1. An apparatus for forming the film was a multi-source simultaneous ion beam sputtering film forming apparatus. In this apparatus, an alloy film having a predetermined composition can be formed if necessary by attaching up to four different sputtering film forming targets. In this example, W, Ni, and Au were used as targets. All over the thin film wiring circuit,
W for the first layer 33-4, Ni-W alloy for the second layer 33-5,
Au is applied to the third layer 33-3 at a thickness of 0.1 μm,
Films are sequentially formed to have a thickness of 1.0 μm and 0.1 μm. At this time, the substrate 8 may be heated. After that, the created metallization was performed using Au in the third layer 33-3, and Au in the second layer 33-5.
The Ni—W alloy and the W of the first layer 33-4 are respectively etched by using hydrofluoric nitric acid to be patterned into an electrode 33 having a diameter of 0.3 mm.

(3) Mounting and assembling process: Next, as shown in FIG. 6, an LSI chip 7 having a solder connection portion plated with Au, a cooling plate 9, a cap 10, and a heat conducting relay member 11
And the connection pins 12 and the wiring board 13 are prepared. As the solder alloy, a first fine solder ball 14 having a composition of 3% by weight of Ag-97% by weight of Sn, a second solder alloy 15 having a composition of 37% by weight of Sn-45% by weight of Pb-18% by weight of Bi, and Pb98 Wt% -Sn2 wt%
And a fourth solder alloy 17 having a composition of 80% by weight of Au and 20% by weight of Sn.
Are prepared and prepared. First, the ceramic substrate 8 and the connection pins 12 are connected by performing a heat treatment at 320 ° C. with the fourth solder alloy 17 interposed therebetween. Next, a small solder ball 14 made of a first solder alloy is interposed between the metal thin film portion 33 for solder connection on the surface of the electronic circuit board 8 formed with the thin film and the electrode terminal of the LSI chip 7. The connection is made by performing a heat treatment at 240 ° C. Next, between the cooling plate 9 and the cap 10,
The connection is performed by performing a heat treatment at 340 ° C. with the third solder alloy 16 interposed. Further, after disposing the heat conducting relay member 11 on the LSI chip 7 connected to the electronic circuit board 8, the space between the periphery of the electronic circuit board 8 and the peripheral portion of the cooling plate 9 and the cap 10 connected earlier. Then, the two are connected by performing a heat treatment at 200 ° C. with the second solder alloy 15 interposed therebetween.

(4) Solder connection-repair characteristic evaluation test:
Next, it will be verified whether or not the connection method using the multilayer metal film 33 for solder connection according to this embodiment realizes a normal connection after repairing many times, which is a technical problem of the present invention.
In order to carry out a repair test, a sample of the metallization 33 having the features of the present invention was formed on the ceramic multilayer wiring board 8, the first layer 33-4 was made of W as a solder underlayer, and the second layer 33-5 was made. Ni-W alloy as a solder reaction layer, and Au as a wetting ensuring layer on the third layer 33-3 are sequentially formed so as to have a thickness of 0.1 μm, 1.0 μm, and 0.1 μm, respectively, and are patterned. After the electrodes are formed, a sample in which the LSI chip 7 is connected by performing a heat treatment at 240 ° C. with a fine solder ball 14 made of a first solder alloy interposed is produced.

For comparison, the ceramic wiring substrate 8
On the upper surface, the metal thin film layer 33 for solder connection is wet in the conventional manner, W is wetted on the first layer 33-4 as a solder underlayer, Ni is used as a solder reaction layer on the second layer 33-5, and the third layer 33-3 is wetted. Au was used as the securing layer, and each film thickness was 0.1 μm.
After sequentially forming a film to have a thickness of 0 μm and 0.1 μm and forming electrodes by patterning, the LSI chip 7 is subjected to a heat treatment at 240 ° C. with fine solder balls 14 made of a first solder alloy interposed. To make a connected sample.

The two samples are repeatedly repaired by the following method, and the solder connection strength of the LSI chip 7 is measured every number of repairs. First, a chip repair method will be described. The LSI chip 7 mounted on the ceramic multilayer substrate 8 is heated by using an infrared lamp so that the temperature of the solder connection becomes 240 ° C., and the solder connection part is melted. In this state, the LSI chip 7 is removed from the substrate 8 by lifting it up. Next, a Cu plate is placed on the substrate 8 at a position corresponding to the removed LSI 7, and is heated to 240 ° C. by an infrared lamp and is lifted upward, so that the first solder 1 remaining on the substrate is removed.
4 is removed, and the solder connection portion 33 of the substrate is flattened. Next, a new LSI chip 7 is connected to the ceramic multilayer wiring board 8 by soldering in the same manner as the method of preparing the sample at first. Thereafter, the repair is repeated in the same manner.

An LSI chip 7 corresponding to each repair count
Was measured by the following method. First, L
A hexagonal metal nut is connected to the upper surface (non-solder connection surface) of the SI chip 7 with an adhesive. Next, this nut is
The chip was rotated on the same surface as the SI chip 7, and the maximum force generated until all of the solder 14 connecting the LSI chip was broken was measured by a tester.

FIG. 11 shows the results of this test performed on a substrate sample 8 having a metallized layer 33 including an alloy layer 33-5 having a composition of Ni: W = 90: 10 at%. As a result, it can be seen that the connection is normal and the connection strength does not decrease until the number of repairs is five. In a state where the connection strength does not decrease, a normal connection is maintained even after the repair, and the metallization 33 withstands the repair up to that number of times. Therefore, this number is set as the maximum number of times that the connection is normally maintained. It is the number of times of repairing of metallization.

FIG. 12 shows this repair test performed on the alloy layer 33-.
5 is a characteristic diagram obtained for a sample in which the composition ratio (expressed in atomic (at)%) of Ni and W is changed. That is, in the figure, Ni: W = 20: 80, 30: 7
0, 50:50, 70:30, 80:20, 85: 1
5, 90:10, 92: 8, 95: 5, 97: 3, 9
Metallization 33 including an alloy layer 33-5 having a composition of 8: 2, 99: 1 at%, and metallization 33 of 100% Ni for comparison were performed, and the number of repairs of the metallization was shown.

From this figure, the number of times of repair is Ni: W = 2
0:80, 30:70, 50:50, 70:30, 8
0:20, 85:15, 90:10, 92: 8, 95:
5, 97: 3, 98: 2, and 99: 1 metallization including alloy layers having the composition of at.
4, 4, 5, 5, 8, 15, 24, 40, and 30 times, and two times with 100% Ni metallization for comparison.

FIG. 13 shows the results of a substrate sample 8 having a metallized layer 33 including an alloy layer 33-5 having a composition of Ni: W = 98: 2 at%. FIG. 13 shows the results together with the results obtained for the substrate sample having Here, as a conventional metallization, W is used as a solder underlayer (barrier layer), Ni is used as a solder reaction layer, and Au is used as a wetting securing layer.
Next, a film was formed to have a thickness of 0 μm and 0.1 μm. FIG. 13 shows that the number of possible repairs in the particularly preferred composition of Ni: W = 98: 2 at% is smaller than the number of possible repairs in the solder thin film layer according to the conventional method. In comparison, it can be seen that it has increased dramatically.

As can be seen from the above examination results, Ni-
The preferable composition ratio of Ni and W in the W alloy layer 33-5 is 2
0 at% ≦ Ni <100 at%, 0 <W ≦ 80 at%, and the solder connection metal film 33 exhibits a repair resistance of three or more times, and more preferably 85 at% ≦ Ni.
When the composition ratio is <100 at% and 0 <W ≦ 15 at%, the number of repairs is 5 or more, more preferably 95 at%.
≦ Ni <100 at%, 0 <W ≦ 5 at% for composition 1
It shows a resistance to repair of 5 or more times, and is particularly preferable at 97 at.
In the composition of% ≦ Ni ≦ 99 at%, 1 at% ≦ W ≦ 3 at%, the number of repairs of 24 or more times was shown. From these results, 20 at% ≦ Ni ≦ 99 at%, 1 at% ≦ W ≦ 8
Each of the metallized layers 33 including the Ni—W alloy layer 33-5 having a composition of 0 at% is formed by a conventional method.
The number of repairs is greater than that of metallization 33 containing i alone (100%), and 97 at% ≦ Ni ≦ 99 a is particularly preferable.
Ni-W having a composition of t%, 1 at% ≦ W ≦ 3 at%
The metallized layer 33 including the alloy layer 33-5 has remarkably improved the number of repairs.

The application of the metal thin film 33 for solder connection according to the present invention is not limited to the connection between the LSI chip 7 and the substrate 8 on which a thin film circuit is formed. For example, a similar effect can be obtained by applying the present embodiment to the connection portion between the electronic circuit board 8 and the cap 10 in FIG. That is, for example, this is effective when the cap 10 is temporarily removed to replace the LSI chip 7 mounted on the substrate 8 and then sealed again. Further, when the LSI chip itself is to be reused by repair, it can be applied as a metal film for solder connection on the LSI.

The Au layer as the outermost layer 33-3 in the metal thin film 33 for solder connection is made of N as the solder reaction layer 33-5.
This is for preventing oxidation of the i-W layer and ensuring solder wettability. If the step does not contaminate the surface, it can be omitted or replaced with another metal. Since the W layer of the lowermost layer 33-4 is a barrier layer for preventing the solder from diffusing to the substrate side and a layer for ensuring adhesion between the substrate and the metallization, another material that does not allow the solder to diffuse, such as Cr, is used. Alternatively, another material having good adhesion to the substrate, for example, Mo may be used, and it is also possible to laminate several metal layers.

The multilayer metal film 33 for solder connection of the present invention
It can be formed by plating, sputtering, vacuum deposition, ion plating, chemical vapor deposition, or the like, as well as ion beam sputtering. For example, a Ni-W
When an alloy layer is formed, a Ni—W alloy layer can be obtained by forming a film using a target having a predetermined composition in advance. In this embodiment, Sn3Ag is used as the first solder 14 for connecting the LSI chip 7 to the substrate. However, other solders, for example, Sn-Ag alloy, Sn, Sn-Pb alloy, Sn-Bi alloy having another composition are used. It is needless to say that similar results can be obtained by using an alloy, a Sn—Pb—Bi alloy, or the like.

<Embodiment 6> This embodiment is similar to the embodiment 1 described above.
Is a modification of the structure of the metal thin film layer 20 for solder connection and its manufacturing process. That is, in the first embodiment, a single thin film layer in which the first metal and the second metal are uniformly mixed is used. However, in the present embodiment, a two-layer structure is used. Although the first metal is more than the second metal, the degree of composition of the first metal is substantially the same as that of the second layer than that of the first layer. The structure is such that the concentration of the first metal is higher on the solder connection surface side than on the substrate side. Except for the process of manufacturing the metal thin film layer, the electronic thin film layer was manufactured in exactly the same steps as in Example 1, and an electronic circuit device having the same configuration as that of FIG. 6 was realized.

Therefore, here, the method of forming the solder connecting metal thin film layer 20 having a two-layer structure, which is a feature of the present invention, will be mainly described. First, a Ni plate (first metal) having a purity of 99.999% and a W plate (second metal) having a purity of 99.999% are used as targets in a device capable of simultaneously sputtering a plurality of targets, for example, a binary simultaneous ion beam sputtering device. Metal) in place. Next, the ceramic multilayer substrate 6 serving as a circuit board is covered with a stainless steel mask from which a predetermined connection pattern has been removed, and is placed at a predetermined position in the sputtering apparatus.

After that, first, a W target is sputtered with a strong intensity by an Ar ion beam or the like, and W is laminated on the ceramic multilayer substrate 6. At the time when the W film thickness becomes about 0.1 μm, the sputtering strength of the W target is reduced, and simultaneously, the sputtering of the Ni target is started.
A 0.2-micron first layer is formed so that Ni and W have a uniform composition of 80% Ni and 20% W in atomic percent. Thereafter, the strength of the W target is further reduced, and Ni
The strength of the target is further increased so that Ni and W have a uniform composition of 95% Ni and 5% W in atomic percent.
A second micron layer is deposited. Thereafter, the sputtering of the W target is stopped, and only the Ni target is subsequently sputtered to make the Ni film thickness 0.1 μm.

According to the above steps, the Ni film serving as the first layer having a thickness of 0.2 μm is formed on the W film having a thickness of about 0.1 μm.
Mixed film of W and W (80% Ni, 20% in atomic percent)
A film having a composition of W) and a mixed film of Ni and W (atomic percent of 9%) serving as a second layer having a thickness of 0.8 μm are formed thereon.
A film having a composition of 5% Ni and 5% W) is formed thereon, and a Ni film having a thickness of 0.1 μm is formed thereon, thereby forming a metal thin film layer 20 having a total thickness of 1.2 μm. At this time,
The ceramic multilayer substrate 6 may be heated to about 100 to 300 ° C. Thus, the metal thin film layer 20 for solder connection
The components 7 such as LSIs are mounted and connected to the ceramic multilayer wiring board 8 on which is formed. However, since these steps are the same as those in the first embodiment, the description is omitted.

Next, it is determined whether the connection method using the metal thin film layer for solder connection according to this embodiment realizes a normal connection after repairing many times, which is a subject of the present invention. An evaluation test was specifically performed in the same manner as in Example 1. The result is shown in FIG. That is, FIG. 14 shows the relationship between the maximum breaking load and the number of repairs in comparison with the conventional method. Here, the conventional metallization means that Cr is used as a solder underlayer (barrier layer), Ni is used as a solder reaction layer, and Au is used as a wetting securing layer. The films were formed in the following order so as to be microns. In the case of the present embodiment, the connection strength does not decrease even when the number of repairs is 20 and it can be seen that the connection is normal. Also,
In the case of this embodiment, since the mixed film of Ni and W has a layer with a high Ni concentration on the solder connection surface side, the wettability of the solder is better than in the case of the first embodiment. Since the number of repairs is increased and a layer having a low Ni concentration is provided on the substrate side, the connectivity with the W layer is improved, and extremely reliable solder connection is enabled. Further, it is easier to manufacture than the mixed film having the concentration gradient of the second embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments but can be further modified. That is, in the above-described embodiment, the metal thin film layer 20 for solder connection of the present invention is formed on the multilayer wiring board 8 for mounting and connecting electronic components such as LSIs, but may be provided on connection electrodes of electronic components depending on the application. It is. Further, for example, in the electronic circuit device having the configuration shown in FIG. 6, the present invention can be applied to a solder connection portion between the multilayer wiring board 8 and the cap 10. In short, the present invention is extremely effective when the solder connection at the same place is repeated, such as once removing the solder connection and reconnecting it. Further, the components of the electronic circuit device are not limited to the example of FIG. The formation of the metal thin film layer for solder connection is not limited to binary simultaneous ion beam sputtering, and may be formed by sputtering a single target in which two types of metals are mixed.

[0075]

As described in detail above, the intended object has been achieved by the present invention. In other words, it is possible to realize solder connection with high resistance to repair, and in order to improve the production yield of electronic circuit devices that are increasingly integrated and highly integrated in the future, especially for the improvement of the production yield of electronic computers, repair of electronic components such as LSIs is indispensable. The present invention can greatly contribute to this. Further, the present invention greatly contributes to the improvement of the reliability such as the strength of the solder connection portion after the repair.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a cross section of an example of a metal thin film for solder connection according to the present invention.

FIG. 2 is a conceptual diagram showing a cross section in a state where solder connection is performed on an example of a metal thin film for solder connection according to the present invention.

FIG. 3 is a conceptual diagram showing a cross-section of a state in which a component is removed after a solder connection is made to an example of a metal thin film for solder connection according to the present invention.

FIG. 4 is a conceptual diagram showing a cross-section of a state in which a single repair is performed after a solder connection is made to an example of a metal thin film for solder connection according to the present invention.

FIG. 5 is a conceptual diagram showing a cross section in a state where repair is performed a number of times after performing solder connection to an example of a metal thin film for solder connection according to the present invention.

FIG. 6 is a partial cross-sectional perspective view showing a configuration of an electronic circuit device according to one embodiment of the present invention.

FIG. 7 is a characteristic curve diagram comparing a connection strength measurement result of an LSI with a conventional example.

FIG. 8 is a characteristic curve diagram comparing the connection strength measurement result of the LSI with the conventional example.

FIG. 9 is an enlarged sectional view of a portion A in FIG. 6 according to another embodiment of the present invention.

FIG. 10 is an enlarged sectional view of a portion B in FIG. 9;

FIG. 11 is a characteristic curve diagram showing a relationship between a maximum breaking load and the number of repairs.

FIG. 12 is a characteristic diagram showing a relationship between the number of repairs and the composition ratio of the Ni—W alloy layer.

FIG. 13 is a characteristic curve diagram comparing the connection strength measurement result of the LSI with the conventional example.

FIG. 14 is a characteristic curve diagram in which the result of measuring the connection strength of an LSI is compared with a conventional example.

[Explanation of symbols]

1 ... first metal, 2 ... second metal, 3 ... one kind of solder component, 4 ... other kind of solder component, 6 ... ceramic substrate,
7 LSI chip, 8 ceramic multilayer wiring board, 9 cooling plate, 10 cap,
11: heat conduction relay member, 12: connection pin,
13: wiring board, 14: solder ball (first solder) 15: second solder alloy, 1
6: third solder alloy, 17: fourth solder alloy, 20, 33 ... metal thin film layer forming a connection part, 3
0: polyimide layer, 31: wiring layer, 3
3-3: Antioxidant layer (Au layer), 33-4: Underlayer (W
Layer), 33-5 ... Solder reaction layer (Ni-W alloy).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Yabushita 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd.Production Technology Laboratory (72) Inventor Naoya Isada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (72) Inventor Kazuhiko Horikoshi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture In-house Hitachi, Ltd. Production Technology Laboratory (56) References JP-A-3-48426 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/60

Claims (15)

(57) [Claims] Claims: 1. Wet with metal constituting solder easily, and
Primary gold that easily alloys or forms intermetallics
Metal and a second that does not easily wet and elute into the solder
And a metal layer mixed with
A metal layer for solder connection comprising: the first metal having a concentration gradient such that the concentration is high on the surface side of the layer.
Metal layer for solder connection. 2. It easily wets with the metal constituting the solder, and
Primary gold that easily alloys or forms intermetallics
Metal and a second that does not easily wet and elute into the solder
And a metal layer mixed with
A solder connection metal layer comprising Te, and constitutes the first metal Au, Cu, Ni, Ti, at least one of Sn and Pt, the second metal W, or at least one of Re and Ta Metal layer for solder connection. 3. The method according to claim 1, wherein the first metal is Au, Cu, Ni, T
i, at least one of Sn and Pt, the second metal is W,
2. The method according to claim 1, wherein said at least one of Re and Ta is used.
The metal layer for solder connection as described. 4. The Ni-W alloy layer according to claim 1, wherein said first metal is composed of Ni and said second metal is composed of W to form a Ni-W alloy layer.
The metal layer for solder connection according to any one of the above. 5. The composition ratio of Ni and W is 20 at% ≦
5. The metal layer for solder connection according to claim 4, wherein Ni <100 at% and 0 <W ≦ 80 at%. 6. A circuit board for mounting electronic components having a metal layer for solder connection, wherein the metal layer for solder connection is constituted by the metal layer for solder connection according to any one of claims 1 to 5. Circuit board for mounting electronic components. 7. The electronic component having a solder connection metal layer, the metal layer for the solder connection according to claim 1 to 5 Noise
An electronic component comprising the metal layer for solder connection according to any one of the above. 8. A method for manufacturing a metal layer for solder connection, comprising the step of selectively forming a metal layer for solder connection forming a connection terminal portion of an electronic component on a predetermined substrate. The forming step comprises a first metal that easily wets with the metal constituting the solder, and easily alloys or forms an intermetallic compound, and a second metal that does not easily wet and elute with the solder. A method for producing a metal layer for solder connection, which comprises a step of forming a thin film layer by mixing as a component. 9. In the step of forming the solder connection metal layer, the first metal in the solder connection metal layer is formed with a concentration gradient such that the first metal has a high concentration on the surface side of the layer. 9. The method for manufacturing a metal layer for solder connection according to claim 8, which is configured as described above. 10. An electronic circuit device comprising an electronic component soldered on a metal layer for solder connection of the electronic component mounting circuit board according to claim 6 via a solder. 11. The method according to claim 11, wherein the solder is a Sn—Pb alloy,
The first metal constituting the metal layer for solder connection is at least one of Au, Cu, Ni, Ti and Pt, and the second metal is composed of at least one of Bi alloy, Sn-Pb-Bi alloy and Sn. 11. The electronic circuit device according to claim 10, wherein the electronic circuit device is formed of at least one of W, Re, and Ta. 12. The method according to claim 11, wherein the solder is an Sn-Ag alloy, Sn-S
b alloy, Sn-In alloy, Pb-In alloy, Pb-Sb
Alloy, Au-Sn alloy, Au-Ge alloy, Sn-Ag-
Sb alloy, Sn-Pb-In alloy, Sn-Pb-Sb alloy, Sn-Pb-Ag alloy, Sn-Bi-In alloy, P
b-Ag-In alloy and at least one of Sn-Pb-Bi-In alloy, and the first metal constituting the metal layer for solder connection is at least one of Au, Cu, Ni, Ti and Sn, The second metal is W, Re and T
11. The electronic circuit device according to claim 10, comprising at least one of a. 13. The solder is made of a Pb-Bi alloy, the first metal constituting the solder connection metal layer is at least one of Au, Ni and Ti, and the second metal is W, Re and 11. The electronic circuit device according to claim 10, wherein the electronic circuit device is configured by at least one of Ta. 14. The solder is composed of a Pb-Ag alloy, the first metal constituting the metal layer for solder connection is at least one of Au, Sn and Ti, and the second metal is W, Re and 11. The electronic circuit device according to claim 10, wherein the electronic circuit device is configured by at least one of Ta. 15. A step of positioning an electrode terminal of an electronic component on a metal layer pattern for solder connection formed on a circuit board for mounting an electronic component according to claim 6, wherein said metal layer and said electrode terminal are connected by solder reflow. A method of manufacturing an electronic circuit device, comprising: a step of soldering.