JP2016167543A - Bonding member and mounting method of electronic component using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding member having good self-alignment properties and bonding strength, and capable of suppressing such a problem that the bonding position of an electronic component is deviated after reflow, especially after the re-reflow, and to provide a mounting method of an electronic component using the same.SOLUTION: A bonding member is formed as a Cu-Ni alloy plating film 2, containing a Cu-Ni alloy as a principal component, on the surface of a base material 8 composed of Cu, and the like, provided on the surface of a wiring board for mounting a plurality of electronic components. The Cu-Ni alloy plating film 2 contains at least one kind of elements of P, B, Au, Pd, Ag, Pt. During a step of reflow soldering an electronic component to the base material 8 via the Cu-Ni alloy plating film 2, an intermetallic compound layer 4 of a layer intermetallic compound is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to, for example, a joining member used for joining an attachment electrode formed on a wiring board and an electronic component, and an electronic component mounting method using the same.

  Conventionally, in order to mount an electronic component, a plate-like wiring board made of resin or the like has been used. Such a wiring board is disclosed in Patent Document 1, for example. The wiring board described in Patent Literature 1 includes external connection pads for joining electronic components by soldering. This external connection pad is made of Cu or Cu alloy and has a surface plating layer on the surface thereof. This surface plating layer is formed of a combination of Ni and Au, a combination of Ni, Pd and Au, Sn, or a combination of Sn and Ag.

JP 2008-300507 A

  In order to join an electronic component to an external connection pad (that is, an attachment electrode) of a wiring board as described in Patent Document 1, reflow soldering is performed. Here, the melting point of the solder after joining the electronic components is not much different from that before joining. Therefore, when the wiring board is again passed through the reflow furnace in order to join the additional electronic component, there has been a problem that the bonded solder is melted again and the position of the electronic component is shifted. There is also a problem that good self-alignment properties cannot be obtained because the alloying speed between the mounting electrode and the solder is too high (that is, the diffusion rate of atoms is too high).

Therefore, the main object of the present invention is to provide a bonding member that has good self-alignment properties and bonding strength, and that can suppress the problem that the bonding position of an electronic component shifts even after reflowing, particularly after reflowing again. Is to provide.
Another object of the present invention is a method for mounting an electronic component that has good self-alignment properties and bonding strength, and that can suppress the problem of misalignment of the bonding position of the electronic component even after reflowing, particularly after reflowing again. Is to provide.

The joining member according to the present invention includes a plating film containing a Cu—Ni alloy as a main component, and the plating film contains at least one element of P, B, Au, Pd, Ag, and Pt. The total content of is 0.05 wt% or more and 1.0 wt% or less, and the Ni content is 3 wt% or more and 20 wt% or less.
Moreover, the joining member according to the present invention has at least one metal layer of Au, Pd, Ag, and Pt on the surface of the plating film, and the total thickness of the metal layers is 0.05 μm or more and 5 μm or less. It is preferable that it is a joining member.
The electronic component mounting method according to the present invention is an electronic component mounting method for mounting an electronic component on a substrate, the step of forming the above-described bonding member on the substrate, and a Sn-based surface on the bonding member. A step of forming a solder layer, and a reflow soldering step of mounting the electronic component on the substrate, melting the joining member and the Sn-based solder layer by reflow soldering, and mounting the electronic component on the substrate, In the reflow soldering process, the electronic component mounting method is characterized by heating at 240 ° C. or higher and 280 ° C. or lower for 180 seconds or longer.

The joining member according to the present invention contains at least one element of P, B, Au, Pd, Ag, and Pt, and the total content of these elements is 0.05 wt% or more and 1.0 wt% or less. In addition, when the Ni content is 3 wt% or more and 20 wt% or less, it has a good self-alignment property and bonding strength, and the bonding position of the electronic component is shifted after reflowing, particularly even after reflowing again. The problem can be suppressed.
Furthermore, the joining member according to the present invention has at least one metal layer of Au, Pd, Ag, and Pt on the surface of the plating film, and the total thickness of the metal layers is 0.05 μm or more and 5 μm or less. As a result, the self-alignment property and the bonding strength are further improved.
Furthermore, an electronic component mounting method according to the present invention is an electronic component mounting method for mounting an electronic component on a substrate, the step of forming the above-described bonding member on the substrate, and a Sn-based surface on the bonding member. A step of forming a solder layer, and a reflow soldering step of mounting the electronic component on the substrate, melting the joining member and the Sn-based solder layer by reflow soldering, and mounting the electronic component on the substrate, The reflow soldering step has an effect that a sufficient intermetallic compound layer can be formed by heating at 240 ° C. or higher and 280 ° C. or lower for 180 seconds or longer.

According to the present invention, it is possible to obtain a bonding member that has good self-alignment properties and bonding strength, and that can suppress the problem that the bonding position of the electronic component shifts even after reflowing, particularly after reflowing again. .
In addition, according to the present invention, the problem that the electronic component has a good self-alignment property and bonding strength, and the bonding position of the electronic component is shifted even after reflowing, particularly after reflowing again, can be suppressed. Can be implemented.

  The above-described object, other objects, features, and advantages of the present invention will become more apparent from the following description of embodiments for carrying out the invention with reference to the drawings.

(A) is a schematic diagram which shows the structure before reflow soldering of the member for joining which concerns on 1st Embodiment of this invention, (b) is based on 1st Embodiment of this invention It is a schematic diagram which shows the structure after reflow soldering of the member for joining. (A) is a schematic diagram which shows the structure before reflow soldering of the member for joining based on 2nd Embodiment of this invention, (b) is based on 2nd Embodiment of this invention. It is a schematic diagram which shows the structure after reflow soldering of the member for joining.

<About the first embodiment>
A joining member according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the structure of a joining member according to this embodiment. FIG. 1A shows a state before soldering, and FIG. 1B shows a state after soldering.

As shown in FIG. 1A, the bonding member according to this embodiment is made of a base material 8 made of Cu or the like provided on a surface of a wiring board (not shown) for mounting a plurality of electronic components. A Cu—Ni alloy plating film 2 mainly composed of a Cu—Ni alloy is formed on the surface. The Cu—Ni alloy plating film 2 contains at least one element of P, B, Au, Pd, Ag, and Pt. The total content of at least one element of P, B, Au, Pd, Ag, and Pt in the Cu—Ni alloy plating film 2 is 0.05 wt% or more and 1.0 wt% or less. Further, the Ni content in the Cu—Ni alloy plating film 2 is 3 wt% or more and 20 wt% or more. Furthermore, an Sn-based solder layer 6 is formed on the surface of the Cu—Ni alloy plating film 2 with an Sn-based solder material.
Then, as shown in FIG. 1B, during the process of reflow soldering the electronic component to the base material 8 via the Cu-Ni alloy plating film 2, the Cu-Ni alloy plating film 2 and the Sn-based solder layer An intermetallic compound layer 4, which is a layered intermetallic compound (IMC), is formed. That is, the intermetallic compound layer 4 of this embodiment is an alloy layer formed at the boundary between the Cu—Ni alloy plating film 2 and the Sn-based solder layer 6, and contains Cu, Ni, and Sn as main components, P , B, Au, Pd, Ag, Pt, at least one element.

<About the intermetallic compound layer 4>
As described above, the intermetallic compound layer 4 is an alloy layer mainly composed of Cu, Ni, and Sn. The intermetallic compound layer 4 having such a composition is formed thicker in a shorter time than a conventional intermetallic compound layer made of Cu and Sn. This mechanism is assumed to be as follows.

  The intermetallic compound layer 4 is formed at the boundary between the Cu—Ni alloy plating film 2 and the Sn-based solder layer 6 during the process of reflow soldering the electronic component to the substrate 8 via the Cu—Ni alloy plating film 2. Is done. That is, the alloying reaction (formation of the intermetallic compound layer 4) proceeds from the interface between the Cu—Ni alloy and the Sn-based metal disposed on the surface thereof.

Here, since the difference between the lattice constant of the Cu—Ni alloy which is the main component of the Cu—Ni alloy plating film 2 and the lattice constant of the intermetallic compound layer 4 formed using this Cu—Ni alloy as a base is large, Part of the intermetallic compound layer 4 is peeled off from the Cu—Ni alloy plating film 2. That is, a part of the surface of the Cu—Ni alloy plating film 2 is exposed. As a result, Cu or Ni of the Cu—Ni alloy plating film 2 and Sn of the Sn-based solder layer 6 come into contact with each other, and the formation of the intermetallic compound layer 4 containing Cu, Ni, and Sn as main components again proceeds.
By repeating the above process, the reaction between Cu and Ni of the Cu—Ni alloy plating film 2 and Sn of the Sn-based solder layer 6 proceeds at a high speed, and a thicker intermetallic compound layer 4 is obtained in a short time. It is done.

  The Cu—Ni alloy plating film 2 according to this embodiment includes at least one element selected from the group consisting of P, B, Au, Pd, Ag, and Pt, and thereby Sn based solder. The rate of alloying with the layer 6 is further reduced. As a result, an effect of improving the self-alignment property at the time of reflow can be obtained.

  Furthermore, the joining member according to the present invention also has an effect that the joining strength is improved. This effect is considered to be due to the fact that, as described above, the alloying speed is sufficiently slow, so that gas can be prevented from remaining as a void at the joint. Conventionally, an oxide film removing agent may be used when bonding. Gases are generated by the decomposition and volatilization of the organic components of the oxide film removing agent during reflow. At this time, if the alloying speed is low, the gas does not completely escape and remains as a void, resulting in poor bonding. However, since the joining member according to the present invention has a sufficiently low alloying speed as described above, it can be avoided that gas remains as a void at the joint.

  When the total content of at least one element among P, B, Au, Pd, Ag, and Pt in the Cu—Ni alloy plating film 2 is smaller than 0.05 wt%, the diffusion rate is sufficiently slowed. Therefore, self-alignment cannot be improved. Further, when the content rate is larger than 1.0 wt%, the high melting point intermetallic compound layer 4 is difficult to be formed, so that the solder that has already been joined is melted at the time of reflow, The position will shift.

  Further, when the Ni content of the Cu—Ni alloy plating film 2 is smaller than 3 wt% and larger than 20 wt%, the high melting point intermetallic compound layer 4 is difficult to be formed. Solder that has been joined is melted, and the position of the electronic component is shifted.

Next, a method for mounting an electronic component using the above joining member will be described.
When an electronic component is mounted on a substrate using the joining member according to the present invention, reflow soldering is performed.
This electronic component mounting method includes a step of forming a Cu—Ni alloy plating film 2 on the surface of a base material 8 by a Cu electrode, a step of forming a Sn-based solder layer 6 on the surface of a bonding member, and an electronic component. A reflow soldering step of mounting the electronic component on the substrate by mounting the electronic component on the substrate by melting the Cu—Ni alloy plating film 2 and the Sn-based solder layer 6 by reflow soldering.
In a reflow soldering process in which an electronic component is mounted on a substrate by reflow soldering, reflow soldering is performed with a profile that is heated at 240 ° C. or higher and 280 ° C. or lower for 180 seconds or longer. When the heating temperature includes a step larger than 280 ° C., the diffusion rate of atoms becomes extremely slow, and a sufficient intermetallic compound layer 4 is not formed. When the heating temperature is lower than 240 ° C., the solder may not be sufficiently melted, so that mounting may not be possible. Further, even when the heating time is shorter than 180 seconds, the sufficient intermetallic compound layer 4 is not formed.

  According to the electronic component mounting method of the present invention, in the reflow soldering step, heating is performed at 240 ° C. or higher and 280 ° C. or lower for 180 seconds or longer, and the Cu—Ni alloy plating film 2 and the Sn-based solder layer 6 according to the present invention are applied. Since the electronic component is mounted on the substrate by melting and reflow soldering, a sufficient intermetallic compound layer can be formed between the Cu—Ni alloy plating film 2 and the Sn-based solder layer 6. There is an effect.

<About the second embodiment>
Hereinafter, a joining member according to a second embodiment of the present invention will be described with reference to the drawings. In addition, since the structure and composition except the intermetallic compound layer 4 and the metal layer 10 are the same as that of the member for joining of 1st Embodiment, the same reference number is attached | subjected to the same part and description which becomes the same is given. Do not repeat.

FIG. 2 is a schematic view showing the structure of the joining member according to this embodiment. FIG. 2A shows a state before soldering, and FIG. 2B shows a state after soldering. As shown in FIG. 2A, the bonding member according to this embodiment includes a Cu—Ni alloy plating film 2 formed on the surface of the substrate 8 and a surface of the Cu—Ni alloy plating film 2. It consists of at least one metal layer 10 of Au, Pd, Ag, and Pt to be formed. The film thickness of the metal layer 10 is 0.05 μm or more and 5 μm or less. Further, an Sn-based solder layer 6 is formed on the surface of the metal layer 10 with an Sn-based solder material.
Then, as shown in FIG. 2B, during the process of reflow soldering the electronic component to the base material 8 via the Cu-Ni alloy plating film 2 and the metal layer 10, the Cu-Ni alloy plating film 2 and An intermetallic compound layer 4, which is a layered intermetallic compound (IMC), is formed between the Sn-based solder layer 6. That is, the intermetallic compound layer 4 of this embodiment contains Cu, Ni, and Sn as main components, and contains at least one element of P, B, Au, Pd, Ag, and Pt, and Au, Pd. , Ag, and Pt.

  By having the metal layer 10 as described above, the bonding member according to this embodiment has an effect that self-alignment properties and bonding strength are further improved as compared to the bonding member of the first embodiment. Play. This effect is because the wettability of the solder is improved and the strength of the formed intermetallic compound layer 4 itself is improved by containing at least one metal of Au, Pd, Ag, and Pt. it is conceivable that.

  The film thickness of at least one metal layer of Au, Pd, Ag, and Pt is preferably 0.05 μm or more and 5 μm or less. When the film thickness is smaller than 0.05 μm, the above effects cannot be obtained sufficiently. Further, when the film thickness is larger than 5 μm, the high melting point intermetallic compound layer 4 is difficult to be formed, so that the solder that has already been joined is melted at the time of reflow, and the position of the electronic component is shifted. End up.

<Experimental example>
Hereinafter, experimental examples conducted by the inventors to confirm the effects of the present invention will be described. In this experimental example, samples for each of Examples 1 to 22 and Comparative Examples 1 to 8 were prepared and evaluated.
As the base material of this example, a large number of Cu electrodes provided on the surface of a glass epoxy substrate (wiring substrate) were used. That is, each of these many Cu electrodes was used as the base material 8 in FIG. 1, and a plating layer was formed on the surface thereof. A Cu electrode having a rectangular shape with dimensions of 0.8 mm in the X direction and 1.5 mm in the Y direction was used. In addition, the pattern of many Cu electrodes is a pair of two Cu electrodes arranged with a spacing of 0.8 mm between each other, and the Cu electrode pairs are spaced at a distance of 1.9 mm in the X direction. 10 sets, 10 sets are arranged at intervals of 2.9 mm in the Y direction. Therefore, the Cu electrode pattern includes 100 Cu electrode pairs (that is, 200 Cu electrodes).

<About Examples 1 to 10>
As Examples 1 to 10, samples of electroless Cu—Ni—P alloy plating were manufactured by the following flow.
First, preparation for forming a plating layer on the surface of the above Cu electrode pattern was performed as follows.
First, degreasing was performed in order to remove dirt that would be an obstacle when forming a plating layer attached to the surface of the Cu electrode.
Next, after washing with water, a soft etching process was performed.
Next, after washing with water, a catalyst was applied, and further washing with water was performed.
As described above, preparations were made for forming a plating layer on the surface of the Cu electrode pattern.
Next, a Cu—Ni—P alloy having a thickness of 10 μm was plated on the surface of the Cu electrode pattern prepared as described above. The plating solution of this Cu—Ni—P alloy is 50 ml / l or more and 200 ml / l or less of OPC Copper AF-M (trade name) manufactured by Okuno Pharmaceutical Co., Ltd., and 50 ml of OPC copper AF-1F (trade name). / L to 200ml / l, OPC Copper AF-2F (trade name) 50ml / l to 200ml / l, and ATS Ad Copper C (trade name) 0ml / l to 30ml / l The temperature of the mixed plating solution used was set to 55 ° C., and the conditions were 100 minutes to 300 minutes.
In all of the samples of Examples 1 to 10, the Ni content is 3 wt% or more and 20 wt% or less, and the P content is 0.05 wt% or more and 1.0 wt% or less. The specific content of each of Examples 1 to 10 is as shown in Table 1 described later.
Next, after washing with water, Sn having a thickness of 10 μm was plated on the surface of the Cu—Ni—P alloy plated as described above.
Finally, drying was performed. Thus, samples of electroless Cu—Ni—P alloy plating of Examples 1 to 10 were obtained.

<About Examples 11-22>
As Examples 11 to 22, samples in which a metal layer was formed on the surface of electroless Cu—Ni—P alloy plating were manufactured by the following flow.
First, preparation for forming a plating layer on the surface of the Cu electrode pattern described above was performed. Since the flow of this preparation is the same as that of Examples 1-10 mentioned above, description is not repeated here.
Next, a Cu—Ni—P alloy having a thickness of 10 μm was plated on the surface of the Cu electrode pattern prepared as described above. The plating solution of this Cu—Ni—P alloy is 50 ml / l or more and 200 ml / l or less of OPC Copper AF-M (trade name) manufactured by Okuno Pharmaceutical Co., Ltd., and 50 ml of OPC copper AF-1F (trade name). / L to 200ml / l, OPC Copper AF-2F (trade name) 50ml / l to 200ml / l, and ATS Ad Copper C (trade name) 0ml / l to 30ml / l The temperature of the mixed plating solution used was set to 55 ° C., and the conditions were 100 minutes to 300 minutes. The plating solution of this Cu—Ni—P alloy is OPC Copper AF-MF (trade name) 150 ml / l, OPC Copper AF-1F (trade name) 100 ml / l, OPC Copper, manufactured by Okuno Pharmaceutical Co., Ltd. Use AF-2F (trade name) 40 ml / l and ATS ad-capper C (trade name) mixed at 0 ml / l to 30 ml / l, and the temperature of the mixed plating solution is 55 ° C. It was performed by dipping under conditions of 100 minutes or more and 300 minutes or less.
All of the samples of Examples 11 to 22 had a Ni content of 3 wt% to 20 wt% and a P content of 0.05 wt% to 1.0 wt%, as in Examples 1 to 10. is there. The specific content of each of Examples 11 to 22 is as shown in Table 1 described later.
Next, after washing with water, on the surface of the Cu—Ni—P alloy plated as described above, in Examples 11-14, a metal layer made of Au, in Examples 15-18, a metal layer made of Ag, Examples 19 to 22 were each plated with a metal layer made of Pd. The thickness of the metal layer is 0.05 μm or more and 5 μm or less. The specific film thickness of each of the metal layers of Examples 11 to 22 is as shown in Table 1 described later.
Next, after washing with water, Sn having a thickness of 10 μm was plated on the surface of the metal layer plated as described above.
Finally, drying was performed. The sample which formed the metal layer (Au metal layer, Ag metal layer, or Pd metal layer) on the surface of the electroless Cu-Ni-P alloy plating of Examples 11-22 by the above was obtained.

<About Comparative Examples 1-4>
As Comparative Examples 1 to 4, samples of electroless Cu—Ni—P alloy plating were produced by the same flow as in Examples 1 to 10 described above.
The Ni content of electroless Cu—Ni—P alloy plating as Comparative Example 1 is 2.9 wt%. That is, the Ni content of Comparative Example 1 is smaller than the lower limit of 3.0 wt% of the Ni content according to the present invention.
The Ni content in the electroless Cu—Ni—P alloy plating as Comparative Example 2 is 21.1 wt%. That is, the Ni content of Comparative Example 2 is greater than the upper limit of 20 wt% of the Ni content according to the present invention.
The P content in electroless Cu—Ni—P alloy plating as Comparative Example 3 is 0.04 wt%. That is, the P content of Comparative Example 3 is smaller than the lower limit of 0.05 wt% of the P content according to the present invention.
The P content of electroless Cu—Ni—P alloy plating as Comparative Example 4 is 1.15 wt%. That is, the P content of Comparative Example 4 is greater than the upper limit of 1.0 wt% of the P content according to the present invention.
The P content in Comparative Examples 1 and 2 and the Ni content in Comparative Examples 3 and 4 are as shown in Table 1 described later.

<Comparative Examples 5 and 6>
As Comparative Examples 5 and 6, a sample in which an Au metal layer was formed on the surface of electroless Cu—Ni—P alloy plating was manufactured by the same flow as in Examples 11 to 14 described above. In addition, the film thickness of each Au metal layer of Comparative Examples 5 and 6 is as follows.
The film thickness of the Au metal layer as Comparative Example 5 is 0.04 μm. That is, the film thickness of the Au metal layer of Comparative Example 5 is smaller than the lower limit of 0.05 μm of the film thickness of the metal layer according to the present invention.
The film thickness of the Au metal layer as Comparative Example 6 is 5.13 μm. That is, the film thickness of the Au metal layer of Comparative Example 6 is larger than the upper limit of 5 μm of the film thickness of the metal layer according to the present invention.
The Ni content and the P content of each of Comparative Examples 5 and 6 are as shown in Table 1 described later.

<About Comparative Example 7>
As Comparative Example 7, a sample of electrolytic Cu—Ni alloy plating was manufactured by the following flow.
First, degreasing was performed on the surface of the Cu electrode pattern described above.
Next, after washing with water, a Cu-Ni alloy with a thickness of 10 μm was plated on the surface of the Cu electrode pattern degreased as described above. This Cu-Ni alloy plating solution is a mixture of nickel sulfate hexahydrate 0.07 mol / L, copper sulfate pentahydrate 0.06 mol / L, sodium gluconate 0.15 mol / L, and an appropriate amount of coating conditioner. We used what we did. The pH of the plating solution is 4.5 and the temperature of the plating solution is 40 ° C. The electrolytic plating current was set to 150 A / m ² and performed under conditions of 110 minutes.
Next, after washing with water, Sn having a thickness of 10 μm was plated on the surface of the Cu—Ni alloy plated as described above.
Finally, drying was performed. Thus, a sample of electrolytic Cu—Ni alloy plating of Comparative Example 7 was obtained.

<About Comparative Example 8>
As Comparative Example 8, a sample in which an Au metal layer was formed on the surface of electroless Ni—P alloy plating was manufactured by the following flow.
First, degreasing was performed on the surface of the Cu electrode pattern described above.
Next, after washing with water, a catalyst was applied.
Next, after the catalyst was washed and washed with water, a Ni-P alloy with a film thickness of 3 μm was plated on the surface of the Cu electrode pattern provided with the catalyst as described above.
Next, after washing with water, Au having a thickness of 0.1 μm was plated on the surface of the Ni—P alloy plated as described above.
Next, after washing with water, Sn having a thickness of 10 μm was plated on the surface of Au plated as described above.
Finally, drying was performed. Thus, a sample in which an Au metal layer was formed on the surface of the electroless Ni—P alloy plating of Comparative Example 8 was obtained.

<About implementation>
The Sn oxide film removing agent (Tamura Seisakusho BF-31) was printed and applied to the mounting portions of the glass epoxy substrates of the samples of Examples 1 to 22 and Comparative Examples 1 to 8, and this Sn oxide film removing agent was applied. In the portion, 100 multilayer ceramic capacitors 2012 size as electronic parts were mounted per glass epoxy substrate using an automatic chip mounting apparatus. The electrode structure of the multilayer ceramic capacitor 2012 is Sn plating 3 μm, Ni plating 3 μm, and Cu thick film electrode in order from the outside to the inside. The glass epoxy substrate was placed on a hot plate at 250 ° C. for 5 minutes to perform reflow, and a multilayer ceramic capacitor was mounted on the glass epoxy substrate.

<About the evaluation method>
(1) Composition of Cu-Ni alloy plating containing P In order to confirm the composition (Cu, Ni, P) of Cu-Ni alloy plating containing P, EDX (energy dispersion) was performed on 10 Cu electrodes in the glass epoxy substrate. Type X-ray spectroscopy), and the average value was obtained as the film composition.

(2) Self-alignment property Self-alignment property was evaluated by setting the number of tests to 500 times. Specifically, after reflow, the multilayer ceramic capacitor is shifted by 0.2 mm or more in the X direction or Y direction of the glass epoxy substrate, or the L direction of the multilayer ceramic capacitor is inclined by 5 ° or more from the X direction of the glass epoxy substrate. The result was NG (defective).

(3) Quantification of low melting point metal component amount of intermetallic compound layer The low melting point metal component contained in the reaction product after reflow was quantified by DSC (differential scanning calorimetry). The measurement conditions are a measurement temperature: 30 ° C. or more and 300 ° C. or less, a heating rate: 5 ° C./min, and a reference: Al ₂ O ₃ in an N ₂ atmosphere. The residual low melting point metal component was quantified from the endothermic amount of the melting endothermic peak at the melting temperature of the low melting point metal component of the measured DSC chart. When the residual low melting point metal content is 0 to 3% by mass, it is larger than 3% by mass, ◯ when it is 30% by mass or less, and x when it is larger than 30% by mass. Possible).

(4) Bonding strength The bonding strength was evaluated by setting the number of tests to 500 times. Specifically, the glass epoxy substrate was dropped 5 times from 1 m above the ground in the vertical direction and the multilayer ceramic capacitor was peeled off to be NG.

  In Table 1, the result of evaluation of Examples 1-22 and Comparative Examples 1-8 is shown.

  As shown in Table 1, Examples 1-22 were able to confirm that any characteristic was favorable compared with Comparative Examples 1-8. In addition, the presence of the metal layer further improved the characteristics. Specifically, it is as follows.

(1) Evaluation about self-alignment About self-alignment evaluation, it was 0-15 times in Comparative Examples 1-8, while it was 0-15 times in NG in Examples 1-22.
In particular, in Comparative Example 3, the number of NG times was 358 times. As described above, this is because the total content of at least one element among P, B, Au, Pd, Ag, and Pt (third element in Table 1) in the Cu—Ni alloy plating film 2 is 0.05 wt. This is because the diffusion rate could not be sufficiently slowed and the self-alignment property could not be improved when it was smaller than%.
From the evaluation results described above, it was confirmed that the examples had superior self-alignment properties compared to the comparative examples.
Moreover, Examples 11-22 were NG 0-3 times, and it has also confirmed that it had a further favorable self-alignment property by the presence of a metal layer. In addition, although the comparative example 5 has Au metal layer, the frequency | count of NG was 20 times. This is because, as described above, since the thickness of the metal layer is smaller than 0.05 μm, the self-alignment effect by the metal layer cannot be sufficiently obtained.

(2) Evaluation for Quantification of Low Melting Point Metal Component Content of Intermetallic Compound Layer For evaluation of quantification of the low melting point metal component amount of the intermetallic compound layer, the residual low melting point metal content in all of Examples 1 to 22 is (0 to 3% by mass), in Comparative Examples 1 to 8, only Comparative Example 3 and Comparative Example 4 are 比較, Comparative Example 5 is ○ (greater than 3% by mass and 30% by mass or less), All of Comparative Examples 1, 2, 4, 6, and 8 were x (greater than 30% by mass, that is, there was a possibility of component deviation due to reflow).
In particular, Comparative Example 1, Comparative Example 2, Comparative Example 4 and Comparative Example 6 had a residual low melting point metal content of x, and there was a possibility of component misalignment during reflow. As described above, this is because the Ni content of the Cu—Ni alloy plating film 2 is smaller than 3 wt% (Comparative Example 1) and larger than 20 wt% (Comparative Example 2), and Cu—Ni alloy plating. When the total content of at least one element among P, B, Au, Pd, Ag, and Pt in the film 2 is larger than 1.0 wt% (Comparative Example 4), and the film thickness of the metal layer is from 5 μm. If it is too large (Comparative Example 6), it is difficult to form a high melting point intermetallic compound layer, and solder that has already been joined is melted during reflow.
From the above evaluation results, it was confirmed that the example had a low residual low melting point metal content compared to the comparative example, and even if reflow was performed again, the occurrence of component misalignment could be suppressed.

(3) Evaluation about joint strength About evaluation of joint strength, it was 0 to 185 times in comparative examples 1-8, while it was NG frequency 0-17 times in Examples 1-22. From this evaluation result, it was confirmed that the example had superior bonding strength as compared with the comparative example.
Moreover, Examples 11-22 were NG times 0-3 times, and it has also confirmed that it had the further outstanding joining strength by the presence of a metal layer. In addition, although the comparative example 5 has Au metal layer, the frequency | count of NG was 35 times. This is because, as described above, since the thickness of the metal layer is smaller than 0.05 μm, the effect of the bonding strength by the metal layer cannot be obtained sufficiently.

In all of Examples 1 to 22, all evaluation results were good, but in Comparative Examples 1 to 8, none of the evaluation results was good. That is, in Comparative Examples 1 to 8, even if one evaluation result was good, it was determined that the other evaluation results were not good.
For example, in Comparative Example 8, the number of NGs of self-alignment property and bonding strength was 0, but the residual low melting point metal content was larger than x (30 mass%. There was a possibility of deviation). In Comparative Example 3, the residual low melting point metal content was ◎ (0 to 3% by mass). On the other hand, the number of self-alignment NG was 358 and the bonding strength was NG. . Similarly, in Comparative Example 7, the residual low melting point metal content was ◎ (0 to 3% by mass), but on the other hand, the number of self-alignment NG times was 286 and the number of NG times of bonding strength was 185 times. It was.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is carried out within the range of the summary.

2 Cu-Ni alloy plating film 4 Intermetallic compound layer 6 Sn-based solder layer 8 Base material 10 Metal layer

Claims (3)

Including a plating film mainly composed of a Cu-Ni alloy,
The plating film is
Containing at least one element of P, B, Au, Pd, Ag, Pt,
The total content of the elements is 0.05 wt% or more and 1.0 wt% or less,
A joining member, wherein the Ni content is 3 wt% or more and 20 wt% or less. Having at least one metal layer of Au, Pd, Ag, and Pt on the surface of the plating film;
The joining member according to claim 1, wherein a total film thickness of the metal layers is 0.05 μm or more and 5 μm or less. An electronic component mounting method for mounting an electronic component on a substrate,
Forming the bonding member according to claim 1 or 2 on the substrate;
Forming a Sn-based solder layer on the surface of the joining member;
Reflow soldering step of mounting the electronic component on the substrate, melting the joining member and the Sn-based solder layer by reflow soldering, and mounting the electronic component on the substrate;
Including
The method of mounting an electronic component, wherein the reflow soldering step includes heating at 240 ° C. or higher and 280 ° C. or lower for 180 seconds or longer.