Device, electrical device, and substrate

Abstract

The purpose of the present invention is to ensure sufficient interfacial strength in a welded portion even after a high-temperature process such as reflow bonding. The device has a base body, an electrode containing Ni and Cu, and a bonding portion on the electrode. The bonding portion includes, in order from the electrode side, a barrier layer, a bonding layer, and a solder layer. The barrier layer contains Mo as a main component; the bonding layer contains at least one of Ni, Ag, Au, and Cu.

Description

Technical Field

[0001] The present disclosure relates to a device, an electrical device, and a substrate. Background Art

[0002] A device equipped with electronic components is mounted on a mounting substrate of an electrical device by solder.

[0003] For example, the surface acoustic wave device described in Patent Document 1 includes a pad (electrode) provided on a piezoelectric substrate and a lower protrusion metal provided on the pad and used for facilitating bonding with solder.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication WO2015 / 022931 Summary of the Invention

[0007] A device according to an aspect of the present disclosure includes: a substrate having a first surface; an electrode located on the first surface of the substrate and containing Ni and Cu; a bonding portion located on the electrode; the bonding portion including a barrier layer, a bonding layer, and a solder layer in this order from the electrode side; the barrier layer containing Mo as a main component; the bonding layer containing at least one of Ni, Ag, Au, and Cu. Brief Description of the Drawings

[0008] Figure 1 It is a cross-sectional structure diagram of the device according to Embodiment 1 of the present disclosure.

[0009] Figure 2 It is a cross-sectional structure diagram of the electronic module according to Embodiment 1 of the present disclosure.

[0010] Figure 3 It is a micrograph of the bonding portion according to Embodiment 1 of the present disclosure.

[0011] Figure 4 It is Figure 3 an enlarged view of the region R in

[0012] Figure 5 It is a cross-sectional structure diagram of the surface acoustic wave device according to Embodiment 2 of the present disclosure.

[0013] Figure 6 It is a micrograph of the bonding portion of the electronic module in Examples and Comparative Examples.

[0014] Figure 7 It is a graph showing the results of evaluating the bonding strength for the comparative example.

[0015] Figure 8 It is a graph showing the results of evaluating the bonding strength for the comparative example.

[0016] Figure 9 This is a graph showing the results of evaluating the bonding strength for the comparative example.

[0017] Figure 10 This is a graph showing the results of evaluating the bonding strength for the example. Detailed implementation mode

[0018] In the case of repeatedly performing high-temperature processes such as reflow bonding, or in the case of using the device at a high temperature for a long time, various metal materials including the lower protrusion metal react with the metals contained in the solder. As a result, the mechanical properties of the solder sometimes deteriorate, and the interfacial strength of the welded part decreases.

[0019] According to one aspect of the present disclosure, sufficient interfacial strength can be ensured at the welded part even after high-temperature processes such as reflow bonding.

[0020] 〔Embodiment 1〕

[0021] Hereinafter, one embodiment of the present disclosure will be described in detail.

[0022] <Structure of the device and the electronic module>

[0023] Hereinafter, the structure of the device 200 as an exemplary device of the present disclosure will be described. The device of the present disclosure can be, for example, an electronic device including a substrate and electronic components such as electronic elements mounted on the substrate.

[0024] Figure 1 This is a cross-sectional structure diagram showing a part of the device 200 according to Embodiment 1 of the present disclosure. Figure 1 This is a cross-sectional structure diagram showing an enlarged part of one electrode 21 included in the device 200, and the electronic components and the like included in the device 200 are not shown.

[0025] The device 200 includes a substrate 110 and a solder layer 33. The substrate 110 includes a base body 11, an electrode 21, a barrier layer 31, and a bonding layer 32. The base body 11 has the electrode 21 on the first surface 11a. In the device 200, the barrier layer 31, the bonding layer 32, and the solder layer 33 are laminated in this order from the electrode 21 side. In the device 200, the barrier layer 31, the bonding layer 32, and the solder layer 33 are referred to as the bonding part 30. That is, the bonding part 30 is located on the electrode 21. The barrier layer 31, the bonding layer 32, and the solder layer 33 are elements constituting the bonding part 30, respectively.

[0026] Figure 2 This is a cross-sectional structure diagram showing a part of the electronic module 300 including the device 200. As Figure 2As shown, the device 200 can be used to form an electronic module 300 by being mounted on a mounting substrate (module substrate) 120. The electronic module 300 is an example of the electrical device of the present disclosure.

[0027] In the electronic module 300, the substrate 110 of the device 200 and the mounting substrate 120 are joined via a solder layer 33. The mounting substrate 120 includes a base body 12, electrodes 22, a barrier layer 31, and a bonding layer 32. The base body 12 has electrodes 22 on a first surface 12a. The barrier layer 31 is located on the electrodes 22, and the bonding layer 32 is located on the barrier layer 31. The barrier layer 31, the bonding layer 32, and the solder layer 33 included in the electronic module 300 are elements constituting a joint portion 30, respectively. In other words, the joint portion 30 is located on the electrodes 22.

[0028] (Substrate, base body)

[0029] The substrate 110 and the mounting substrate 120 are examples of the substrate 100 of the present disclosure. Hereinafter, for the common content of the substrate 110 and the mounting substrate 120, the substrate 110 and the mounting substrate 120 may be collectively referred to as the substrate 100 for description.

[0030] The substrate 110 is a substrate on which electronic components are mounted, and may include internal wirings located inside the substrate 110 and through conductors that connect the internal wirings vertically to each other.

[0031] The base body 11 included in the substrate 110 may be composed of a single layer or multiple layers. The base body 11 has a first surface 11a and a second surface 11b located on the opposite side of the first surface 11a. Electronic components such as electronic elements may be mounted on the first surface 11a or the second surface 11b.

[0032] The base body 11 may have insulation. In this case, the material of the base body 11 may be, for example, ceramics such as aluminum nitride sintered body, alumina sintered body (alumina ceramic), silicon nitride sintered body, mullite sintered body, or glass ceramic sintered body. Alternatively, the material of the base body 11 may include: epoxy resin, polyimide resin, acrylic resin, phenolic resin, and fluorine-based resin. As an example of the fluorine-based resin, it may be resin such as polyester resin and tetrafluoroethylene resin.

[0033] The mounting substrate 120 is a circuit board of an electronic module, and may have circuits inside and / or outside the mounting substrate.

[0034] (Electrode)

[0035] The electrodes 21 and 22 are examples of the electrode 20 of the present disclosure. For the common content of the electrodes 21 and 22, the electrodes 21 and 22 may be collectively referred to as the electrode 20 for description.

[0036] The electrode 21 provided on the substrate 110 electrically connects the device 200 and the circuit board. The electrode 21 is located on the first surface 11a of the base 11. The substrate 110 may have a plurality of electrodes 21 on the first surface 11a.

[0037] The substrate 110 may have a metallization layer different from the electrode 21 on the surface of the base 11. The metallization layer includes, for example, a metallization layer provided in the mounting area of the electronic component mounted in the base 11 and capable of electrically connecting to the electronic component.

[0038] When the base 11 is made of electrically insulating ceramic, the metallization layer contains, for example, any one of W (tungsten), Mo (molybdenum), Mn (manganese), Ag (silver), Ni, and Cu, or an alloy containing at least one of them. When the base 11 is made of resin, the metallization layer contains, for example, any one of Cu, Au (gold), Al (aluminum), Ni, Mo, and Ti (titanium), or an alloy containing at least one of them. The internal wiring and the through conductor also have the same structure as the alloy of the metallization layer.

[0039] The electrode 22 provided on the mounting substrate 120 electrically connects the mounting substrate 120 to an electronic device or the like. The electrode 22 is located on the first surface 12a of the base 12.

[0040] The electrode 20 may be made of an alloy containing Ni (nickel) and Cu (copper). The electrode 21 may contain other metals in addition to Ni and Cu.

[0041] (Barrier layer)

[0042] The barrier layer 31 is a layer containing Mo as the main component. The manufacturing process of the device 200 and the electronic module 300 includes a soldering process as a high-temperature process. In the absence of the barrier layer 31 and the bonding layer 32, for example, when performing flow soldering, the molten high-temperature solder is applied to the electrode 21. When performing reflow bonding, each device 200 or electronic module 300 with solder applied to the electrode portion is heated in a reflow furnace. In addition, due to the heat generation of the module during the use of the electronic module 300, etc., the solder joint is sometimes repeatedly or continuously exposed to a high-temperature state. In this case, the electrode metals such as Cu and Ni contained in the electrode 20 dissolve and react with the metals such as Sn (tin) and Cu contained in the solder, thereby forming a metal compound. Since the metal compound is hard and brittle, it easily becomes the starting point of cracks.

[0043] By positioning the barrier layer 31 between the electrode 20 and the solder layer 33, the likelihood of reaction between the electrode metal contained in the electrode 20 and the metal contained in the solder layer can be reduced. In other words, the diffusion of the electrode metal into the solder layer can be decreased. Thereby, the formation of metal compounds can be reduced. The thickness of the barrier layer 31 can be, for example, 0.1 μm or more. By having a thickness of 0.1 μm or more, the likelihood of reaction between the electrode metal and the metal of the solder layer can be significantly reduced.

[0044] (Bonding layer)

[0045] The bonding layer 32 is located between the solder layer 33 and the barrier layer 31 and is a layer containing at least one of Ni, Ag, Au, and Cu. Since the wettability of the solder is ensured by the presence of the bonding layer 32, the interfacial strength of the solder interface can be improved.

[0046] The bonding layer 32 may also contain Ni, Ni - Sn compounds, Cu, or Cu - Sn compounds as the main components. Since Ni and Cu have excellent wettability with respect to the solder, the interfacial strength can be further improved.

[0047] In the state of the substrate 100 before soldering, the thickness of the bonding layer 32 can be less than the thickness of the electrode 20. For example, the thickness of the bonding layer 32 can be 0.1 μm or more and 1 μm or less, or it can be 0.1 μm.

[0048] In a high - temperature state such as soldering, sometimes the metal contained in the bonding layer 32 reacts with the metal contained in the solder to form metal compounds. By making the thickness of the bonding layer 32 the above - mentioned thickness, the amount of metal dissolved from the bonding layer 32 during soldering etc. can be reduced, and thus the amount of formed metal compounds can be reduced. In addition, since the amount of metal dissolved from the sufficiently thin bonding layer 32 is small, it is not easy to form coarse particles of metal compounds and it is not easy to become brittle. That is, a joint portion 30 that ensures the wettability of the solder and has excellent interfacial strength can be achieved.

[0049] (Solder layer)

[0050] The solder layer 33 is a layer containing metals such as Sn, Ag, and Cu.

[0051] (Regarding the bonding layer in a device or an electronic module)

[0052] Figure 3 is Figure 2 A micrograph of the joint portion 30 in the electronic module 300 shown. Figure 4 is Figure 3 An enlarged view of the region R in. Figure 3 and Figure 4The micrograph shown is of the electronic module 300 that has been soldered in a reflow oven. In the device 200 and the electronic module 300, the solder layer 33 is melted by heating during soldering in the manufacturing process. At this time, at least a part of the metal in the bonding layer 32 reacts with the metal contained in the solder layer 33 to form one or more compounds. Figure 4 Region C in Figure 4 is a region containing a relatively large amount of this compound. The one or more compounds include, for example, Ni - Sn compounds and Cu - Sn compounds.

[0053] For example, when the bonding layer 32 before soldering is mainly composed of Ni, region C contains Ni 3 Sn 4 、Ni 3 Sn 2 、Ni 3 Sn、(Cu,Ni) 3 Sn 4 and (Cu,Ni) 6 Sn 5 and at least one or more of the compounds in

[0054] Based on the above, in the device 200 or the electronic module 300, the bonding layer 32 may contain Ni, Ni - Sn compounds, Cu, or Cu - Sn compounds as the main components.

[0055] As Figure 4 shown, the bonding layer 32 may be a prescribed layer between the upper surface of the barrier layer 31 and the surface that is substantially parallel to the upper surface of the barrier layer 31 and located at the top of region C. Or, it may also be a prescribed layer between the upper surface of the barrier layer 31 and the boundary on the solder layer side of region C. In this case, the bonding layer 32 may be a layer with irregularities, and a part of it may also have holes.

[0056] Based on the above, by the substrate 100 having the barrier layer 31 and the bonding layer 32, it is possible to ensure the wettability of the solder during soldering and reduce the amount of Sn - containing compounds formed near the interface between the solder layer 33 and the bonding layer 32. Thereby, the substrate 100 can provide a device or an electronic module that has sufficient interface strength at the soldered portion even after high - temperature processes such as reflow bonding.

[0057] In addition, since the device 200 and the electronic module 300 include the substrate 100 and the joint portion 30, it is possible to ensure sufficient interface strength at the soldered portion even after high - temperature processes such as reflow bonding.

[0058] 〔Embodiment 2〕

[0059] Other embodiments of the present disclosure will be described below. For ease of explanation, components having the same functions as those described in the above embodiments are denoted by the same reference numerals, and their descriptions will not be repeated.

[0060] In Embodiment 2, an example in which the device 200 is an elastic wave device will be described. Figure 5 It is a cross-sectional structure diagram of the elastic wave device 210 of Embodiment 2.

[0061] The elastic wave device 210 includes a substrate 130 and a solder layer 33. The substrate 130 includes a base body 13, an electrode layer 23, a barrier layer 31, and a bonding layer 32. The elastic wave device 210 can be mounted on a circuit board (mounting substrate) of a communication device.

[0062] The base body 13 includes a piezoelectric layer 13A and a support substrate 13B that supports the piezoelectric layer 13A. The piezoelectric layer 13A has a first surface 13a on the side opposite to the surface joined to the support substrate 13B. The electrode layer 23 is provided on the first surface 13a of the piezoelectric layer 13A. In the elastic wave device 210, the barrier layer 31, the bonding layer 32, and the solder layer 33 are laminated in this order from the electrode layer 23 side. In the elastic wave device 210, the barrier layer 31, the bonding layer 32, and the solder layer 33 are referred to as a bonding portion 30. That is, the bonding portion 30 is located on the electrode layer 23. The barrier layer 31, the bonding layer 32, and the solder layer 33 are elements constituting the bonding portion 30, respectively. The base body 13 is not limited to the above structure. For example, the base body 13 may not include the support substrate 13B. In this case, the piezoelectric layer 13A itself also functions as the support substrate 13B.

[0063] The base body 13 is an example of the base body 10 of the present disclosure, and the substrate 130 is an example of the substrate 100 of the present disclosure.

[0064] The electrode layer 23 includes an IDT (Interdigital Transducer) electrode 231 and a pad portion 232. The pad portion 232 includes a first pad 232A and a second pad 232B. The pad portion 232 in the present embodiment is an example of the electrode 20 of the present disclosure. The first pad 232A and the second pad 232B are laminated in this order from the base body 13 side. That is, the pad portion 232 may include multiple layers. The first pad 232A may have the same thickness as the IDT electrode 231. The pad portion 232 has a laminated structure, thereby enabling reduction of resistance.

[0065] The IDT electrode 231 is a comb-shaped electrode that generates elastic waves in the elastic wave device. The IDT electrode 231 includes a pair of electrodes to which an alternating voltage is applied. The IDT electrode 231 and the pad portion 232 are electrically connected.

[0066] The elastic wave device 210 is characterized by having fewer joint parts joined via the joint part 30 compared with other electronic devices. Therefore, ensuring the interfacial strength in the joint part 30 is more emphasized. The elastic wave device 210 has a substrate 130 and the joint part 30, so that sufficient interfacial strength can be ensured at the soldered part even after high-temperature processes such as reflow soldering.

[0067] In Embodiment 2, although the SAW (Surface Acoustic Wave) is described as the elastic wave device, it is not limited thereto. For example, it may also be a BAW (Bulk Acoustic Wave).

[0068] 〔Verification test〕

[0069] Hereinafter, a verification test for verifying the effects of the substrate, device, and electrical device of the present disclosure will be described.

[0070] (Verification test 1: Comparison based on micrographs)

[0071] Figure 6 is a micrograph of the joint part of the electronic module. Figure 6 The reference numeral 6001 in is a micrograph of the joint part 30 in the electronic module 300 of the embodiment of the present disclosure. Figure 6 The reference numeral 6002 in is a micrograph of the joint part of the electronic module as a comparative example. In the electronic module of the comparative example, the solder layer is located between the electrode on the electronic device side and the mounting substrate. That is, it does not have the barrier layer 31 and the joint layer 32 of the present disclosure. The heating conditions during soldering are the same in both the embodiment and the comparative example.

[0072] In Figure 6 In the comparative example shown by the reference numeral 6002 in, near the interface of the joint part, there is a region C, which is a coarse granular region and contains more compounds formed by the reaction of the metals contained in the electrode metal and the solder layer. In addition, since the electrode metal is more dissolved into the solder layer side, voids P are formed at the interface of the joint part.

[0073] On the other hand, in Figure 6 In the electronic module 300 of the present disclosure shown by the reference numeral 6001 in, the region C existing near the interface of the joint part 30 is only a small region. In addition, the voids P observed in the comparative example are not observed.

[0074] That is, it is confirmed that by having the barrier layer 31 and the bonding layer 32 of the present disclosure, even after high-temperature processes such as reflow bonding, the formation of brittle compounds in the solder portion can be significantly reduced. In addition, it is also confirmed that since the dissolution of the electrode metal into the solder layer side is reduced, the possibility of generating voids at the interface between the electrode and the joint portion can be reduced.

[0075] Based on the above, it is confirmed that the substrate, device, and electrical device of the present disclosure can ensure sufficient interfacial strength at the solder portion even after high-temperature processes.

[0076] (Confirmation Test 2: Bonding Strength Test)

[0077] Figures 7 to 10 It is a graph showing the results of evaluating the bonding strength in the case of changing the metal used for the barrier layer. The evaluation test of the bonding strength was carried out according to the solder ball shear standard of JEDEC JESD22 - B117.

[0078] In Comparative Example 1, it is configured to stack a Ni layer as an electrode on the substrate, stack a TaN (tantalum nitride) layer as a barrier layer, and place a solder ball thereon. Figure 7 It shows the results of the test carried out after performing 1 reflow process and the test carried out after performing 3 reflow processes on the structure of Comparative Example 1.

[0079] In Comparative Example 2, it is configured to stack a Ni layer as an electrode on the substrate, stack a TiN (titanium nitride) layer as a barrier layer, and place a solder ball thereon. Figure 8 It shows the results of Comparative Example 2.

[0080] In Comparative Example 3, it is configured to stack a Ni layer as an electrode on the substrate, stack a W (tungsten) layer as a barrier layer, and place a solder ball thereon. Figure 9 It shows the results of Comparative Example 3.

[0081] In the Example, it is configured to stack a Ni layer as an electrode on the substrate, stack a Mo (molybdenum) layer the same as the barrier layer 31 of the present disclosure as a barrier layer, and place a solder ball thereon. Figure 10 It shows the results of the Example.

[0082] In Comparative Example 1 and Comparative Example 2, in any case of 1 reflow process, 3 reflow processes, etc., it is a graph in which the load drops sharply at a small displacement. This indicates that peeling at the solder interface occurs at the displacement where the interfacial strength is weak and the load drops sharply.

[0083] In Comparative Example 3, in the case of one reflow process, within the test range of displacement, it is not a graph in which the load drops sharply. The gentle drop in load indicates that overall failure of the solder occurred rather than peeling. However, in the result of three reflow processes, it is still a graph in which the load drops sharply at small displacements. That is to say, this indicates that the interface strength becomes weak due to repeated reflow processes.

[0084] On the other hand, in the examples, in any case of one reflow process, three reflow processes, etc., within the test range of displacement, it is not a graph in which the load drops sharply. That is to say, it is confirmed that the interface strength is maintained within the test range of displacement.

[0085] Based on the above test results, it is confirmed that by using the Mo layer as the barrier layer 31, sufficient interface strength can be ensured at the welding part even after high-temperature processes such as reflow bonding.

[0086] (Summary)

[0087] (1) The device according to the first aspect of the present disclosure has: a substrate having a first surface; an electrode located on the first surface of the substrate, containing Ni and Cu; a bonding portion located on the electrode; the bonding portion sequentially includes a barrier layer, a bonding layer, and a solder layer from the electrode side; the barrier layer contains Mo as a main component; the bonding layer contains at least one of Ni, Ag, Au, and Cu.

[0088] (2) The device according to the second aspect of the present disclosure is based on the device according to the first aspect, and the thickness of the barrier layer is 0.1 μm or more.

[0089] (3) The device according to the third aspect of the present disclosure is based on the device according to the first or second aspect, and the bonding layer contains Ni, Ni - Sn compound, Cu, or Cu - Sn compound as a main component.

[0090] (4) The device according to the fourth aspect of the present disclosure is based on the device according to any one of the first to third aspects, the electrode is disposed on a piezoelectric layer and is connected to an IDT electrode.

[0091] (5) The electrical device according to the fifth aspect of the present disclosure includes the device according to any one of the first to fourth aspects of the present disclosure.

[0092] (6) The substrate according to the sixth aspect of the present disclosure has: a substrate having a first surface; an electrode located on the first surface of the substrate, containing Ni and Cu; a barrier layer located on the electrode; a bonding layer located on the barrier layer; the barrier layer contains Mo as a main component; the bonding layer contains at least one of Ni, Ag, Au, and Cu.

[0093] (7) On the basis of the substrate of the sixth aspect of the present disclosure, for the substrate of the seventh aspect of the present disclosure, the thickness of the bonding layer is less than the thickness of the electrode.

[0094] (8) For the substrate of the eighth aspect of the present disclosure, on the basis of the substrate of the sixth or seventh aspect of the present disclosure, the thickness of the bonding layer is 0.1 μm or more and 1 μm or less.

[0095] As described above, the invention of the present disclosure has been described based on the respective drawings and embodiments. However, the invention of the present disclosure is not limited to the above-described embodiments. That is, the invention of the present disclosure can be variously modified within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means separately disclosed in different embodiments are also included in the technical scope of the invention of the present disclosure. That is to say, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. In addition, it should be noted that these deformations or modifications are included in the scope of the present disclosure.

[0096] Symbol Explanation

[0097] 10, 11, 12, 13: Substrate

[0098] 20, 21, 22: Electrode

[0099] 30: Joint portion

[0100] 31: Barrier layer

[0101] 32: Bonding layer

[0102] 100, 110, 130: Substrate

[0103] 120: Mounting substrate

[0104] 200: Device

[0105] 210: Surface acoustic wave device (device)

[0106] 13A: Piezoelectric layer

[0107] 13B: Support substrate

[0108] 23: Electrode layer

[0109] 231: IDT electrode

[0110] 232: Pad portion (electrode)

[0111] 300: Electronic module (electrical device).

Claims

1. A device, comprising: a substrate having a first surface; an electrode located on the first surface of the substrate, comprising Ni and Cu; a bonding portion located on the electrode; the bonding portion sequentially comprising a barrier layer, a bonding layer, and a solder layer from the electrode side; the barrier layer comprising Mo as a main component; the bonding layer comprising at least one of Ni, Ag, Au, and Cu.

2. The device according to claim 1, wherein the thickness of the barrier layer is 0.1 μm or more.

3. The device according to claim 1 or 2, wherein the bonding layer comprises Ni, a Ni-Sn compound, Cu, or a Cu-Sn compound as a main component.

4. The device according to any one of claims 1 to 3, wherein the electrode is disposed on a piezoelectric layer and is connected to an IDT electrode.

5. An electrical device comprising the device according to any one of claims 1 to 4.

6. A substrate, comprising: a substrate having a first surface; an electrode located on the first surface of the substrate, comprising Ni and Cu; a barrier layer located on the electrode; a bonding layer located on the barrier layer; the barrier layer comprising Mo as a main component; the bonding layer comprising at least one of Ni, Ag, Au, and Cu.

7. The substrate according to claim 6, wherein the thickness of the bonding layer is less than the thickness of the electrode.

8. The substrate according to claim 6 or 7, wherein the thickness of the bonding layer is 0.1 μm or more and 1 μm or less.

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