Wiring substrate, electronic device package, and electronic device

Abstract

In a wiring substrate having an insulating substrate and a metallization layer on the surface of the insulating substrate, the bonding strength between the insulating substrate and the metallization layer is improved compared with the conventional ones. The wiring substrate (3) comprises: an insulating substrate (31) comprising aluminum oxide; and a metallization layer (32) having a metal phase comprising a metal material and a first glass phase comprising a glass component, and the metallization layer is located on the insulating substrate (31), at least one of the insulating substrate (31) and the metallization layer (32) further comprises mullite, the metal phase (M) of the metallization layer (32) is connected to form a three-dimensional mesh, and the first glass phase (G) enters between the metal phases (M).

Description

Technical Field

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

[0002] Conventionally, there is known a wiring substrate including an insulating substrate made of an insulating material such as alumina and a metallization layer provided on the surface of the insulating substrate and made of a metal material such as molybdenum.

[0003] In addition, in the wiring substrate, in order to improve the bonding strength between the insulating substrate and the metallization layer, the first surface portion of the insulating substrate that is in contact with the metallization layer and the second surface portion of the metallization layer that is in contact with the insulating substrate are set to contain at least one of a manganese silicate phase and a magnesium silicate phase (for example, refer to patent document 1).

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2018 / 155053 Summary of the invention

[0007] -Methods for solving problems-

[0008] The wiring substrate of the present disclosure comprises:

[0009] an insulating substrate comprising alumina; and

[0010] The metallization layer has a metal phase including a metal material and a first glass phase including a glass component, and the metallization layer is located on the insulating substrate.

[0011] Furthermore, in the wiring substrate of the present disclosure, at least one of the insulating substrate and the metallization layer further includes mullite.

[0012] In addition, in the metallization layer, the metal phases are connected to form a three-dimensional mesh, and the first glass phase enters between the metal phases. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an exploded perspective view of an electronic device according to an embodiment of the present disclosure.

[0014] Figure 2 yes Figure 1 A three-dimensional diagram of input and output terminals of an electronic device.

[0015] Figure 3 yes Figure 2 An enlarged view of a cross section of a wiring substrate having input and output terminals.

[0016] Figure 4 yes Figure 1 A list of manufacturing conditions of test samples and results of peeling tests involved in examples of embodiments of the present invention. DETAILED DESCRIPTION

[0017] In recent years, there has been a demand for further improvement in the performance of wiring substrates. Specifically, there has been a demand for improving the bonding strength between the insulating substrate and the metallization layer while maintaining the mechanical strength and dielectric constant of the insulating substrate at the same level as the wiring substrate described in Patent Document 1.

[0018] The wiring board, electronic device package, and electronic device according to the present embodiment utilize the structure of the metallization layer 32 to improve the bonding strength between the insulating substrate and the metallization layer compared to the prior art.

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0020] However, the technical scope of the present disclosure is not limited to the following embodiments and the contents illustrated in the drawings.

[0021] 〔Electronic devices〕

[0022] First, a schematic configuration of the electronic device 100 according to the present embodiment will be described. Figure 1 is an exploded perspective view of the electronic device 100. Figure 2 It is a perspective view of input and output terminals included in the electronic device 100 .

[0023] like Figure 1 As shown, the electronic device 100 according to the present embodiment includes an electronic device package (hereinafter referred to as a package 100a) and an electronic component 100b.

[0024] The package 100 a includes a case 10 and input / output terminals 20 .

[0025] The housing 10 includes a main body 1 and a cover 2 .

[0026] The main body 1 is made of a metal material and has a box shape having a recessed portion 11 .

[0027] Examples of the metal material include copper, copper alloys, iron / nickel alloys, iron / nickel / cobalt alloys, and stainless steel.

[0028] The main body 1 according to the present embodiment includes a bottom portion 1 a and a frame portion 1 b .

[0029] The bottom portion 1 a is made of metal and has a rectangular plate shape in plan view.

[0030] The frame 1b is made of metal and has a rectangular frame shape that is substantially equal to the outline of the bottom 1a when viewed from above. The lower surface of the frame 1b is joined to the peripheral edge of the upper surface of the bottom 1a. Thus, the area surrounded by the upper surface of the bottom 1a and the inner surface of the frame 1b becomes the recess 11.

[0031] In addition, the main body 1 may be configured such that the bottom portion 1a and the frame portion 1b are integrated (not separated into individual components).

[0032] A fitting portion 12 is provided on one side wall portion of the main body 1 .

[0033] The fitting portion 12 before the input / output terminal 20 is fitted is an opening that passes through the main body 1 (frame portion 1 b ). That is, the fitting portion 12 corresponds to an opening that passes through the recess 11 and the outside.

[0034] Furthermore, a hole 13 is provided in a side wall portion of the main body 1 that is opposed to one side wall portion.

[0035] An optical connecting member (not shown) is provided in the hole 13 . The optical connecting member functions as an optical waveguide for optically connecting the electronic component 100 b and an optical device (not shown) disposed outside the housing 10 .

[0036] The cover 2 is made of the same metal material as the main body 1 and is in the shape of a rectangular plate having a substantially equal shape to the bottom 1a when viewed from above. The lower peripheral edge of the cover 2 is bonded to the upper surface of the frame 1b. As a result, the recess 11 of the main body 1 is closed, thereby hermetically sealing the electronic component 100b described later.

[0037] The input / output terminal 20 is fitted into the fitting portion 12 of the case 10 , and is brazed to the case 10 by a brazing material 30 (for example, AgCu).

[0038] like Figure 2 As shown, the input / output terminal 20 according to the present embodiment includes a plurality of wiring substrates 3 , another wiring substrate 4 , and a plating layer 5 .

[0039] More specifically, the input / output terminal 20 according to the present embodiment includes two wiring substrates 3 ( 3 a , 3 b ), one wiring substrate 3 a is located at the uppermost portion of the input / output terminal 20 , and the other wiring substrate 3 b is located at the lowermost portion of the input / output terminal 20 .

[0040] In addition, if Figure 1 , 2 As shown, the upper surface of the wiring substrate 3 a constituting the uppermost portion and the lower surface of the wiring substrate 3 b constituting the lowermost portion respectively form metallization layers 32 .

[0041] The wiring substrate 3 will be described in detail later.

[0042] The other wiring substrate 4 constitutes the middle portion of the input / output terminal 20. That is, in the input / output terminal 20, the other wiring substrate 4 is located between the wiring substrate 3a constituting the uppermost portion and the wiring substrate 3b constituting the lowermost portion.

[0043] The other wiring substrate 4 has a pair of first end portions 4 a and a second end portion 4 b in a direction connecting the outside of the housing 10 and the recessed portion 11 .

[0044] When the input / output terminal 20 is fitted in the housing 10, the first end 4a extends outward from the outer side of the housing 10, and the second end 4b extends toward the recess 11 from the inner side of the housing 10. That is, the first end 4a is located outside the housing 10, and the second end 4b is located inside the housing 10.

[0045] In addition, the upper surface portion of the other wiring substrate 4 serves as wiring 41 .

[0046] The wiring 41 extends from the first end 4a to the second end 4b . Thus, the end of the wiring 41 on the first end 4a side is located inside the recess 11 of the housing 10 , and the end of the wiring 41 on the second end 4b side is located outside the housing 10 .

[0047] Furthermore, a plurality of wirings 41 may be provided.

[0048] The plating layer 5 according to the present embodiment is provided on the upper surface of the wiring board 3 a and the lower surface of the wiring board 3 b .

[0049] As described above, the upper surface of the wiring substrate 3a and the lower surface of the wiring substrate 3b are respectively formed into the metallization layer 32. Therefore, the plating layer 5 covers the surface of the metallization layer 32.

[0050] Then, the brazing material 30 is sandwiched between the plating layer 5 and the housing 10 .

[0051] As the metal of the plating layer 5, Ni is mentioned, for example.

[0052] like Figure 1 As shown, the electronic component 100 b is housed in the recess 11 of the housing 10 .

[0053] The electronic component 100 b and the end portion of the wiring 41 on the second end portion 4 b side are electrically connected via a conductive connection member (for example, a bonding wire or the like) not shown.

[0054] Furthermore, by connecting another electronic component (not shown) to the end portion of the wiring 41 on the first end portion 4 a side, the electronic component 100 b is electrically connected to the other electronic component.

[0055] 〔Wiring substrate〕

[0056] Next, a specific structure of the wiring board 3 provided with the above-mentioned input / output terminal 20 will be described. Figure 3 , 4 It is an enlarged view of the cross section of the wiring substrate 3 .

[0057] like Figure 3 As shown, the wiring substrate 3 includes an insulating substrate 31 and a metallization layer 32 .

[0058] The insulating substrate 31 according to the present embodiment is a plate-like shape having a rectangular shape in plan view.

[0059] In addition, the insulating substrate 31 according to the present embodiment includes alumina (aluminum oxide) and mullite. Specifically, the insulating substrate 31 according to the present embodiment includes an alumina sintered body and a mullite sintered body.

[0060] Mullite has a smaller relative dielectric constant than alumina. Therefore, the insulating substrate 31 according to the present embodiment can reduce the transmission loss of a signal when a high-frequency signal is transmitted through the metallization layer 32 .

[0061] In addition, when the metallization layer 32 (metal paste in the manufacturing stage) contains mullite, the insulating substrate 31 does not need to contain mullite.

[0062] In addition, compared with alumina, mullite has a lower mechanical strength. Therefore, generally speaking, there is a tendency that the strength of the insulating substrate decreases in accordance with the amount of mullite added. However, in the insulating substrate 31 involved in this embodiment, the crystals of alumina are miniaturized, that is, the insulating substrate 31 is densified. Therefore, the insulating substrate 31 involved in this embodiment can maintain the same degree of strength as the case where mullite is not included.

[0063] The insulating substrate 31 according to the present embodiment may also have a ratio of mullite in the range of 30 to 80 volume % relative to the entire insulating substrate 31. In this case, the dielectric constant of the insulating substrate 31 is lower than that of alumina (8 or less), and the bending strength of the insulating substrate 31 is equal to or greater than that of alumina (400 MPa or more).

[0064] Insulating substrate 31 may also be a structure formed by stacking a plurality of insulating layers. In this case, at least the insulating layer in contact with metallization layer 32 among the plurality of insulating layers may contain alumina and mullite. In addition, other insulating layers may not contain mullite, for example.

[0065] The metallization layer 32 covers the surface of the insulating substrate 31 .

[0066] Furthermore, the metallization layer 32 contains a metal material.

[0067] The melting point of the metal material used in this embodiment is higher than the temperature (1100° C. or higher) required for firing the insulating substrate 31 .

[0068] Specifically, as the metal material, at least one of manganese, molybdenum, and tungsten can be cited.

[0069] Furthermore, the metal material may be a single substance of each of the above-mentioned metals, or at least one of them may be a compound. Examples of the compound include oxides or silicates of other metals.

[0070] Furthermore, when a plurality of metals are used as the metal material, an alloy may be used.

[0071] Furthermore, the metallization layer 32 may contain filler powder including at least one inorganic material such as alumina particles and mullite particles in addition to the metal material.

[0072] In particular, when a material containing both alumina particles and mullite particles is used, preferable electrical characteristics (dielectric constant) and bending strength can be exhibited.

[0073] In addition, when the insulating substrate 31 includes mullite, the metallization layer 32 may not include mullite.

[0074] Furthermore, the metallization layer 32 contains at least a glass component derived from mullite.

[0075] Furthermore, the metallic material of the metallization layer 32 forms a metallic phase M.

[0076] Furthermore, the metallized layer 32 has a mesh structure based on the mutual intrusion of the metal phase M and the first glass phase G1 including a glass component.

[0077] The “mutually intrusive network structure” refers to a structure in which the metal phases M are connected to form a three-dimensional network and the first glass phase G1 enters between the metal phases M.

[0078] That is, the phases G1 and M exist in a state of being intertwined with each other. Therefore, when observing a certain cross section of the metallization layer 32, for example, Figure 3 As shown, the metal phase M appears to be divided into a plurality of parts in the first glass phase G1. In addition, when observing other cross sections of the metallization layer 32, the metal phase M appears to be integrated, while the first glass phase G1 appears to be divided into a plurality of parts in the metal phase M.

[0079] The metal phase M is not dispersed in the first glass phase G1 , and is not dissolved in the first glass phase G1 .

[0080] In addition, the first glass phase G1 is not dispersed in the metal phase M, and is not dissolved in the metal phase M either.

[0081] In addition, the mutual intrusion mesh structure involved in this embodiment exists throughout the entire metallization layer 32. In other words, Figure 3 As shown in the figure, the metal phase M and the first glass phase G1 intertwined with each other can be observed throughout the entire area in the direction along the boundary surface between the insulating substrate 31 and the metallized layer 32 (the entire area in the surface direction). Furthermore, the metal phase M and the first glass phase G1 intertwined with each other can also be observed throughout the entire area in the direction perpendicular to the boundary surface between the insulating substrate 31 and the metallized layer 32 (the entire area in the thickness direction) (not shown). That is, in a cross section when the surface layer of the metallized layer 32 on the side away from the insulating substrate 31 is cut parallel to the boundary surface between the insulating substrate 31 and the metallized layer 32, the metal phase M and the first glass phase G1 intertwined with each other can be observed. In addition, in a cross section when the boundary portion of the metallized layer 32 on the side close to the insulating substrate 31 is cut parallel to the boundary surface, the metal phase M and the first glass phase G1 intertwined with each other can also be observed.

[0082] In addition, the ratio of the metal phase in each boundary portion may be within a range of 60 to 70%, and may further be approximately 50%.

[0083] The metallized layer 32 has such a mutual intrusion network structure, and thus it becomes difficult to cut off the bond between the metal phase M and the first glass phase G1 . Therefore, the metallized layer 32 is difficult to be peeled off from the insulating substrate 31 .

[0084] Furthermore, at least one of the interface between the metal phase M and the first glass phase G1 in the metallization layer 32 and the interface between the metal phase M and the second glass phase G2 of the insulating substrate according to the present embodiment may have irregularities.

[0085] Although described in detail later, the unevenness is caused by the spread of the grain size distribution of mullite included in the insulating substrate 31 .

[0086] Due to the projections and recesses, an anchor effect is generated between at least one of the metal phase M and the first glass phase G1 and between the metal phase M and the second glass phase G2 , so that the metallization layer 32 becomes more difficult to be peeled off from the insulating substrate 31 .

[0087] The above-mentioned plating layer 5 is provided on the surface of the metallization layer 32. In other words, the wiring board 3b constituting the lowermost portion of the input / output terminal 20 has a structure in which the metallization layer 32 is provided on the lower surface of the insulating substrate 31.

[0088] The other wiring substrate 4 may be composed of the insulating substrate 31 and the metallization layer 32 in the shape of wiring. In this case, the metallization layer 32 constitutes wiring 41 that electrically connects the electronic component 100b to another electric circuit different from the electronic device 100.

[0089] At this time, the plating layer 5 may be provided on the surface of the metallization layer 32 constituting the wiring 41 .

[0090] [Method for manufacturing wiring substrate]

[0091] Next, a method for manufacturing the above-mentioned wiring substrate 3 will be described.

[0092] The method for manufacturing the wiring board 3 according to the present embodiment includes a preparation step, a sheet preparation step, a first firing step, a paste preparation step, a coating step, and a second firing step.

[0093] In the initial preparation step, in order to stabilize the sinterability of the insulating substrate 31, mullite synthesized with alumina is mixed and uniformly dispersed.

[0094] In order to stabilize the sinterability and achieve the stability of shrinkage, alumina and mullite are finely pulverized into a powder state while adjusting the pulverized particle size.

[0095] Alumina was pulverized to an average particle size of about 1.5 μm.

[0096] Mullite is less hard than alumina and is easily crushed. Therefore, even if the particle sizes of alumina and mullite as the starting materials are the same, the progress of alumina crushing and mullite crushing will be different. As a result, even if the average particle size of mullite particles is in the range of 1.5 to 2.0 μm, there will be a large amount of fine powder (average particle size <1.0 μm) with a particle size smaller than that of alumina particles. As a result, the particle size distribution of mullite particles is wider than that of alumina particles.

[0097] In the paste preparation step described later, when a filler including mullite particles is added to the metal paste, the mullite may not be pulverized in this step, and mullite may not be included in the ceramic green sheet in the next step.

[0098] After the alumina and mullite are pulverized, the process proceeds to a sheet forming step in which a slurry is prepared by kneading alumina powder and mullite powder with an organic binder and an organic solvent.

[0099] Furthermore, during the kneading, at least one additive selected from silicon oxide (silicon dioxide), manganese oxide, molybdenum oxide, and magnesium oxide may be added to the slurry.

[0100] Then, the slurry is formed into a sheet by a doctor blade method or the like to produce a ceramic green sheet.

[0101] After the ceramic green sheets are produced, the process proceeds to the first firing step. In this step, the insulating substrate 31 is produced by firing the ceramic green sheets.

[0102] The calcination temperature can be set within a range of 1300 to 1600°C.

[0103] In the first firing step, by firing a stacked body formed by stacking a plurality of ceramic green sheets, it is possible to produce an insulating substrate 31 formed by stacking a plurality of insulating layers.

[0104] In this manner, the ceramic green sheet becomes the insulating substrate 31 .

[0105] As described above, compared with alumina, mullite has a lower mechanical strength. Therefore, the strength of the insulating substrate 31 generally decreases in accordance with the amount of mullite added. However, in this embodiment, as alumina particles, microparticles with an average particle size of about 1.5 μm are used. Therefore, the crystals of alumina formed during sintering also become fine crystals. Therefore, the insulating substrate 31 is densified and can maintain the same degree of strength as the case where mullite is not included.

[0106] In addition, when forming the ceramic green sheet, at least one additive selected from manganese, magnesium and silicon dioxide may be added to the slurry. In this way, the additive slows down the crystallization of alumina and mullite. As a result, the insulating substrate 31 is densified and the mechanical strength is improved.

[0107] After the insulating substrate 31 is manufactured, the process proceeds to the paste manufacturing step. In this step, a metal paste is manufactured by kneading raw material powders, such as molybdenum powder and manganese powder as main raw materials, and appropriate organic solvents and binders. The materials are kneaded, for example, by milling.

[0108] In the present embodiment, filler powder including at least one of alumina particles and mullite particles is added to the metal paste during kneading.

[0109] Furthermore, the same material as the additive added to the ceramic green sheet (at least one of silicon oxide (silicon dioxide), manganese oxide, molybdenum oxide, and magnesium oxide) may be added to the metal paste.

[0110] In addition, when mullite particles are added to the insulating substrate 31 , filler powder including mullite particles may not be added to the metal paste in this step.

[0111] The paste preparation step does not need to be performed after the above-mentioned firing step, and may be performed at any timing until the firing step is completed.

[0112] After the insulating substrate 31 is manufactured, the process proceeds to the coating process. In this process, the metal paste produced in the paste manufacturing process is coated on the surface (either side in the thickness direction) of the insulating substrate 31. At this time, the metal paste is applied by a method such as screen printing to a thickness that will become the metallized layer 32 after firing.

[0113] After the metal paste is applied to the insulating substrate 31, the process proceeds to the second firing step. In this step, the insulating substrate 31 on which the metal paste has been applied is fired.

[0114] The calcination temperature can be set within a range of approximately 1100 to 1400°C.

[0115] During the firing period, at least one of the mullite in the metallization layer and the mullite in the insulating substrate 31 is decomposed, so that at least one of the first glass phase G1 and the second glass phase G2 (hereinafter, marked as the first and second glass phases G1 and G2) is dissolved. Moreover, the first and second glass phases G1 and G2 cover the surface of the aluminum oxide particles that exist as cores in the metal paste. In addition, the dissolved first and second glass phases G1 and G2 also cover the surface of a portion of the mullite particles that are not dissolved and remain. As a result, the magnetic components (alumina, mullite, and the first glass phase) in the metal paste are combined and connected to form a mutually intrusive mesh structure in which the first and second glass phases G1 and G2 are entangled with the metal phase M.

[0116] Furthermore, when the filler powder added to the metal paste includes only alumina particles, a mutual intrusion network structure is similarly formed.

[0117] In this way, the metal paste becomes metallization layer 32 , and wiring board 3 according to the present embodiment is manufactured.

[0118] In addition, when the filler powder added to the metal paste includes only mullite particles, a portion of the mullite particles in the metal paste remain without being dissolved. Therefore, the dissolved first glass phase G1 covers the surface of a portion of the mullite particles (remaining without being dissolved) that exist as cores in the metal paste. As a result, a mutual intrusion mesh structure that is relatively close to the case where alumina particles are added is formed in the metallization layer 32.

[0119] In addition, when no filler is added to the metal paste (in this case, mullite must be added to the insulating substrate 31), the mullite in the insulating substrate 31 dissolves and enters the gaps between the metal particles in the metal paste, thereby filling the gaps. Thus, a certain degree of mutual intrusion mesh structure is formed.

[0120] In addition, a part of the mullite particles in the insulating substrate 31 or the mullite particles in the metal paste is decomposed to generate the first and second glass phases G1 and G2. As described above, the particle size distribution of the mullite particles is relatively wide. That is, in the insulating substrate 31, large particles of mullite and small particles are mixed. Such large and small mullite particles mixed together become cores, and the cores cover the dissolved first and second glass phases G1 and G2, thereby forming concavo-convex on the surface of the first and second glass phases G1 and G2.

[0121] In addition, at this time, the first and second glass phases G1 and G2 and the gaps between the first and second glass phases G1 and G2 are filled with the metal phase M. As a result, projections and depressions are formed at least at one of the interfaces between the metal phase M and the first glass phase G1 of the metallization layer 32 and the interface between the metal phase M and the second glass phase G2 of the insulating substrate 31. Such projections and depressions improve the bonding strength between the insulating substrate 31 and the metallization layer 32.

[0122] Furthermore, if aluminum oxide particles are added to the metal paste, even when mullite particles are not added to the metal paste (only the second glass phase G2 is dissolved from the insulating substrate 31), the aluminum oxide particles in the metal paste will become nuclei to form a mutually intrusive mesh structure. Therefore, the bonding strength between the insulating substrate 31 and the metallized layer 32 can be improved.

[0123] Furthermore, if filler powder is added to the metal paste, the filler powder remains in a solid state during firing, and the viscosity of the first glass phase G1 in the metal paste can be maintained above a given value. Therefore, the first glass phase G1 becomes difficult to flow. As a result, the first glass phase G1 and the metal phase M are more complexly entangled.

[0124] In particular, when aluminum oxide particles are added as filler powder, it becomes easy to plate the metallization layer 32 later.

[0125] Furthermore, the dew point of the firing atmosphere in the second firing step may be lowered.

[0126] Mullite decomposes in a reducing atmosphere. That is, the lower the dew point of mullite, the stronger its reducing property is, which can promote decomposition. Therefore, if the mullite is fired in a firing atmosphere with a low dew point, more glass components are dissolved from the mullite during sintering, which can further improve the bonding strength between the insulating substrate 31 and the metallized layer 32.

[0127] The method for manufacturing wiring board 3 according to the present embodiment includes a first firing step for producing insulating board 31 and a second firing step for forming metallization layer 32. However, firing for producing the insulating board and firing for forming the metallization layer may be performed simultaneously.

[0128] [Wiring board bonding strength]

[0129] Next, the bonding strength of the wiring substrate 3 will be described. Figure 4 This is a table showing the manufacturing conditions of the test samples and the results of the peeling test.

[0130] Prior to the description, test samples (Examples 1 to 10) including various types of wiring substrates 3 were produced using the method for manufacturing the wiring substrate 3 according to the present disclosure.

[0131] Specifically, first, metal pastes having different compositions (the presence or absence of molybdenum powder alone or molybdenum powder and manganese powder, and filler powder (additive), and the proportion (volume %) of the filler powder) were prepared.

[0132] Then, different metal pastes are applied to the surfaces of the plurality of insulating substrates 31 manufactured through the above-mentioned preparation step to the first firing step.

[0133] The sintering temperature of each insulating substrate 31 and the metal paste was set to 1350°C.

[0134] Then, Ni plating was performed on the surface of the metallization layer 32 of each wiring board 3 produced.

[0135] Next, a brazing material was placed on the surface of the plated layer, and a metal fitting was further placed on the surface of the brazing material to perform brazing.

[0136] The brazing temperature was set at 850°C.

[0137] Next, each sample was subjected to a peeling test.

[0138] Specifically, the metal fittings of each sample were pulled and peeled off, and the surface of the wiring board 3 after the metal fittings were peeled off was observed. Then, the observation results were evaluated based on the following evaluation criteria.

[0139] (Evaluation Criteria)

[0140] △...There is a metallization layer remaining on part of the surface

[0141] ○...There is a lot of metallization layer remaining on the surface

[0142] ◎...surface residual metallization layerMore

[0143] In addition, the samples evaluated as ◎ or ○ have greater bonding strength as products. In addition, the samples evaluated as △ also have bonding strength that can be used as products.

[0144] Furthermore, the remaining rate (%), which is the ratio of the area of ​​the remaining metallization layer 32 to the entire surface area of ​​the wiring substrate 3 after the metal fittings are peeled off, was calculated.

[0145] As a result of the test, the samples of Examples 1 and 6 in which no filler powder (alumina particles or mullite particles) was added to the metal paste were evaluated as △. On the other hand, the samples of Examples 2, 3, 5, 7 to 10 in which filler powder was added to the metal paste were evaluated as ○ or ◎.

[0146] The remaining rates of the metallization layer 32 in the samples of Examples 1 and 6 were 15 and 28%, respectively. In contrast, the remaining rates of the metallization layer 32 in the samples of Examples 2, 3, 5, 7 to 10 were 25, 35, 39, 32, 42, 43, and 57%, respectively.

[0147] That is, from the experimental results, it is found that the sample in which the filler powder is added to the metal paste tends to improve the bonding strength between the insulating substrate 31 and the metallization layer 32 .

[0148] In addition, the samples of Examples 2, 4, 7, and 9, which had relatively small amounts of filler powder added to the metal paste, were evaluated as ○, △, ○, and ○, respectively. In contrast, the samples of Examples 3, 5, 8, and 10, which had relatively large amounts of filler powder added to the metal paste, were evaluated as ◎, ○, ◎, and ◎, respectively.

[0149] The remaining rates of the metallization layer 32 in the samples of Examples 2, 4, 7, and 9 were 25, 23, 32, and 43%, respectively. In contrast, the remaining rates of the metallization layer 32 in the samples of Examples 3, 5, 8, and 10 were 35, 39, 42, and 57%, respectively.

[0150] That is, from the experimental results, it is found that there is a tendency that the bonding strength between the insulating substrate 31 and the metallization layer 32 increases as the amount of filler powder added to the metal paste increases.

[0151] The samples of Examples 4 and 5 using mullite particles as filler powder were evaluated as △ and ○, respectively. On the other hand, the samples of Examples 2 and 3 using the same amount of alumina as filler powder were evaluated as ○ and ◎, respectively.

[0152] Furthermore, the residual rates of the metallization layer 32 in the samples of Examples 4 and 5 were 23 and 39%, respectively, whereas the residual rates of the metallization layer 32 in the samples of Examples 2 and 3 were 25 and 35%, respectively.

[0153] That is, the experimental results show that, when the amount of filler powder added is the same, the use of alumina particles tends to increase the bonding strength between the insulating substrate 31 and the metallization layer 32 compared to the use of mullite particles.

[0154] As a result, it is presumed that the number of crystal nuclei decreased because mullite was decomposed and flowed into glass during firing.

[0155] The samples of Examples 4 and 5 including both molybdenum powder and manganese powder as metal powder were evaluated as △ and ○, respectively. On the other hand, the samples of Examples 9 and 10 including only molybdenum powder as metal powder were evaluated as ○ and ◎, respectively.

[0156] Furthermore, the residual rates of the metallization layer 32 in the samples of Examples 4 and 5 were 23 and 39%, respectively, whereas the residual rates of the metallization layer 32 in the samples of Examples 9 and 10 were 43 and 57%, respectively.

[0157] That is, from the experimental results, it is found that there is a tendency that the bonding strength between the insulating substrate 31 and the metallization layer 32 is improved in the sample in which the metal paste does not contain the manganese powder.

[0158] This is presumably because part of manganese was dissolved during firing to form manganese silicate crystals and flow.

[0159] In the wiring substrate 3 according to the present embodiment described above, the metal phase M and the first glass phase G1 form a mesh structure in which the metal phase M and the first glass phase G1 penetrate each other in the metallization layer 32. Therefore, the metal phase M and the first glass phase G1 become difficult to separate in the metallization layer 32. As a result, the bonding strength between the insulating substrate 31 and the metallization layer 32 of the wiring substrate 3 according to the present embodiment is improved compared with the conventional ones.

[0160] In addition, if the electronic device 100 is used continuously, the housing 10 and the input / output terminals 20 will be heated. The housing 10 of the electronic device 100 is metal, while the input / output terminals 20 are mostly ceramic. Therefore, the method of thermal expansion of the housing 10 when the electronic device 100 is heated and the method of thermal expansion of the input / output terminals are different. Therefore, the housing 10 and the input / output terminals 20 will be subjected to stress accompanying the difference in thermal expansion. In addition, for this difference in thermal expansion, the wiring substrate with mullite added will be more significant than the wiring substrate formed only by alumina. That is, the wiring substrate involved in the present embodiment with mullite added is also subjected to greater stress than the wiring substrate formed only by alumina. However, the input / output terminals 20 of the package 100a involved in the present embodiment are soldered to the housing 10 via the metallization layer 32 with high bonding strength as described above. Therefore, in the electronic device 100, even if a large stress is applied to the housing 10 and the input / output terminal 20, the joint between the housing 10 and the input / output terminal 20 is not easily damaged. As a result, the electronic device 100 can easily maintain the reliability of the electrical connection between the electronic component 100b and other electronic components connected to the outside for a long time.

[0161] -Industrial Applicability-

[0162] The present disclosure can be utilized in a wiring substrate, an electronic device package, and an electronic device.

[0163] -Explanation of symbols-

[0164] 100 Electronic devices

[0165] 100a Package for electronic devices

[0166] 10 Housing

[0167] 1 Main body

[0168] 1a Bottom

[0169] 1b Frame

[0170] 11 recess

[0171] 12 Chimeric part

[0172] 13 holes

[0173] 2 Cover

[0174] 20 Input and output terminals

[0175] 3 (3a, 3b) Wiring board

[0176] 31 Insulation substrate

[0177] 32 Metallization layer

[0178] G1 First glass phase

[0179] G2 Second glass phase

[0180] M Metal phase

[0181] 4 Other wiring substrates

[0182] 4a First end

[0183] 4b Second end

[0184] 41 Wiring

[0185] 5 Plating

[0186] 30 Brazing materials

[0187] 100b Electronic components.

Claims

1. A wiring substrate comprising: an insulating substrate comprising alumina; and a metallization layer having a metal phase including a metal material and a first glass phase including a glass component, and the metallization layer is located on the insulating substrate, At least one of the insulating substrate and the metallization layer further comprises mullite, In the metallization layer, the metal phases are connected to form a three-dimensional mesh, the first glass phase enters between the metal phases without being dispersed in the metal phases, and the first glass phase and the metal phase are entangled with each other.

2. The wiring substrate according to claim 1, wherein: The metallization layer includes aluminum oxide.

3. The wiring substrate according to claim 1, wherein The insulating substrate has a second glass phase including a glass component, At least one of a first interface between the metal phase and the first glass phase and a second interface between the metal phase and the second glass phase includes projections and depressions.

4. The wiring substrate according to any one of claims 1 to 3, wherein: The dielectric constant of the insulating substrate is lower than that of alumina, and the bending strength of the insulating substrate is equal to or higher than that of alumina.

5. The wiring substrate according to any one of claims 1 to 3, wherein: The insulating substrate has a plurality of laminated insulating layers. At least one of the plurality of insulating layers that is in contact with the metallization layer contains mullite and aluminum oxide.

6. The wiring substrate according to claim 5, wherein: The plurality of wirings are located on the upper surface of at least the second insulating layer or lower from the top among the plurality of insulating layers.

7. The wiring substrate according to any one of claims 1 to 3, wherein: The insulating substrate includes mullite, and a particle size of at least a portion of the mullite included in the insulating substrate is smaller than an average particle size of alumina included in the insulating substrate.

8. The wiring substrate according to any one of claims 1 to 3, wherein: The insulating substrate includes mullite, and an average particle size of aluminum oxide included in the insulating substrate is equal to or smaller than an average particle size of the mullite included in the insulating substrate.

9. The wiring substrate according to any one of claims 1 to 3, wherein: The insulating substrate includes mullite, and the ratio of the mullite included in the insulating substrate is 30 to 80 volume %.

10. A package for an electronic device, comprising: The wiring substrate according to any one of claims 1 to 9; and The housing is made of metal and has a recess and an opening that passes through the recess and the outside. The wiring substrate is fitted into the opening.

11. An electronic device comprising: The electronic device package according to claim 10; and The electronic component is housed in the recessed portion of the electronic device package.

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