JP2909856B2 - Joint of ceramic substrate and metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined body of a ceramic substrate and a metal, and is suitably used, for example, for joining metal fittings (input / output pins, seal rings, leads, etc.) on a package / multilayer substrate.

[0002]

2. Description of the Related Art Conventionally, an alumina substrate (α = 6.8 × 10 ⁻⁶ / ° C.) has been mainly used for an IC package. Metal fittings of Fe-Ni-Co) and 42 alloy (Fe-Ni) are made.

However, alumina has a relatively large dielectric constant, causing signal propagation delay, a large coefficient of thermal expansion, a great difference from a silicon semiconductor chip, and a high firing temperature.
There is a drawback that it cannot be fired simultaneously with a good conductor such as silver or copper. Therefore, in order to respond to high density and high speed, development of low thermal expansion materials and low dielectric constant materials that have characteristics such as low dielectric constant, thermal expansion coefficient close to silicon semiconductor chips, and low firing temperature as an alternative to alumina Is required. Materials satisfying these requirements include glass ceramics (α = 1.5 to 5.0 × 10 ⁻⁶ / ° C), aluminum nitride (α
= 4.4 × 10 ⁻⁶ / ° C.), and the use of substrates such as mullite (α = 3.8 × 10 ⁻⁶ / ° C.) are being studied (Japanese Patent Publication No. 3-37308,
JP-A-3-21046).

[0004]

However, the above low thermal expansion material has a thermal expansion coefficient of a silicon chip (α = 3.0 to 3.5).
× 10 ⁻⁶ / ° C), the alumina substrate (α = 6.8 × 10 ⁻⁶⁾ was used as described above when joining metal fittings.
/ ° C), when a brazing material (eutectic silver brazing) and a metal (Kovar, 42 alloy) used in metal fittings are used, the difference in thermal expansion coefficient between the substrate and the metal becomes large, and cracks and the like due to thermal stress are caused. There was a problem that a defect occurred and a good bonding state could not be obtained.

[0005] It is an object of the present invention to provide a joined body and a joining method with good airtightness between a low thermal expansion ceramic substrate and a metal.

[0006]

Means for solving the problem are as follows.
The coefficient of thermal expansion at 0 ° C. is 1.5 to 5.0 × 10 ⁻⁶ /
In a predetermined portion of the ceramics substrate is ° C., ceramics
Sputtered layer and plating layer were laminated in order from the substrate side
Forming a metal film of a multilayer structure, a metal which is also a thermal expansion coefficient in the metal film is 1.5~5.0 × ^{10 -6} / ℃, A
conjugate ceramics substrate and the metal, characterized in that joined by a brazing material consisting of g-Cu-In alloy, in.

Further, desired means, ceramic substrate, is AlN, SiC, mullite, _Si 3 _{N 4,} ceramics composed mainly of cordierite, the above conjugates comprising glass-ceramics or crystallized glass.
Also desirable is the above joint, wherein the metal is low thermal expansion Kovar. As the above low thermal expansion Kovar
Is particularly Ni 31% (% by weight, the same applies hereinafter), Co
14%, 31Ni-14Co with the balance being Fe
-Fe alloys are preferred. Another desirable means is the above-mentioned joined body, wherein the silver-based brazing material is an Ag—Cu—In alloy. As the Ag-Cu-In alloy, in particular, Ag
72% (% by weight, the same applies hereinafter), Cu 22%, In 1
A 5% Ag-Cu-In brazing material is preferred. Similarly, a desirable means is that the metal film is formed sequentially from the ceramic substrate side .
The above joined body has a multilayer structure in which a putter layer and a plating layer are laminated. As the metal film,
Ti sputtering film, Mo spa in order from the ceramic substrate side
Film, Cu sputtered film, Cu plating and Ni plating
Is preferably a multi-layer structure in which is laminated.

As shown in Table 1, low thermal expansion Kovar means that conventional Kovar (29 N
Ni-C having a lower coefficient of thermal expansion than i-16Co-Fe)
o-Fe alloy, for example, 31Ni-14Co-F
e alloy is available.

[0009]

[Table 1]

The silver brazing material having a solidus of 650 ° C. or less (eg, Ag
72% (% by weight, the same applies hereinafter), Cu 22%, In
15% Ag-Cu-In row : solidus 600-65
0 ° C.), the eutectic A which has been conventionally used
The temperature at which the brazing material begins to have a proof strength is about 100 ° C. lower than g-row (Ag72-Cu28: solidus 780 ° C., liquidus 780 ° C.). By using the metal thermal expansion coefficient at 30 to 400 ° C. is 1.5~5.0 × ^{10 -6} / ℃ opposite material of low thermal expansion ceramics substrate, the temperature of brazing material has a yield strength Se <br/> ceramic scan board and becomes less difference in thermal expansion between the substrate in the range, as a result, it becomes possible to alleviate the thermal stress, it just tens
It is not possible to reduce the thermal stress. So this application
According to the invention, thermal stress relaxation is applied to a predetermined portion of the ceramic substrate.
Form a multi-layered metal film with a function as a layer,
A row made of an Ag-Cu-In alloy is interposed through this metal film.
This problem was solved by joining with materials.

[0010] That is, in order from the ceramic substrate side, T
i-sputtered film, Mo-sputtered film, Cu-sputtered film, Cu
Since the brazing of the substrate and the metal fitting is performed via a metal film having a multilayer structure in which plating and Ni plating are laminated , the wettability of the brazing material, the adhesion strength, and the metal film are thermally stressed. The effect of acting as a relaxation layer is obtained. Since a brazing material made of an Ag-Cu-In alloy is used, there is no problem in a process after joining, for example, mounting of a silicon chip, a lid seal, and the like. Moreover, among the metal film, Ti sputtered film is to ensure adhesion strength between the ceramics substrate, Mo sputtered film adhesion strength deterioration of the metal film and the brazing material and the titanium film brazing material is diffused is reacted The Cu sputtered film improves the adhesion between the sputtered film and the copper plating, and the Cu plating relieves thermal stress.
It acts as a buffer material for, Ni plating except that improve the wettability of the brazing material, to prevent leaching of copper by brazing material.

[0011]

【Example】

Example 1 The coefficient of thermal expansion was 3.0 × 10 ⁻⁶ / ° C. (room temperature to
400 ° C.), a dielectric constant 5.1 (1 MH _Z, room temperature), the composition is ZnO: 4wt%, MgO: 13wt %, Al
₂ O ₃ : 23 wt%, SiO ₂ : 58 wt%, B
₂ O ₃ : 1 wt%, P ₂ O ₅ : 1 wt% crystallized glass, 20 × 20 × 1.0 mm square ceramic substrate, outer diameter □ 20 × inner diameter □ 18.5 × 0.03 mm metal seal ring and seal A test was performed using the same preform as that of the ring in the following procedure.

The Ti film 2000 # and the Mo film 300 are sputtered on the brazing portion of the ceramic substrate by sputtering.
0, a Cu film 5000 is sequentially formed, and Cu plating 1 is formed thereon.
After performing 0 μm and Ni plating of 0.5 μm, sintering of the plating was performed in a belt furnace (about 500 ° C., in N ₂ ) to obtain a bonding test substrate. Low melting point brazing material (Ag63-Cu22-In15: solidus 630 ° C, liquidus 685 ° C)
For comparison, a test was also conducted with a eutectic silver low (Ag72-Cu28: solidus 780 ° C., liquidus 780 ° C.). The metal was also tested as a comparative example with Kovar, a 42 alloy in addition to Kovar with low thermal expansion.

The quality of the joint is checked by inspection of appearance (presence or absence of cracks), airtightness test (He leak test 3 × 10 ⁻⁸⁾
STD, CC / SEC or less), environmental test (temperature cycle test 150 ° C 30 minutes → -65 ° C 30 minutes 100 cycles, thermal shock test 150 ° C 30 minutes → -65 ° C 30 minutes 100 cycles, pressure cooker・ Test 125 ℃ 1.7atm100
h) After the airtightness test, three tests were performed to make a judgment. Table 2 shows the results.

[0014]

[Table 2] As a result of the test, no crack occurred in the combination of the low melting point brazing material and the low thermal expansion Kovar, and both the airtightness and the airtightness after the environmental test were good. In other combinations, defects such as cracks and poor airtightness of the substrate occurred, and good bonding could not be obtained.

Embodiment 2 Using a ceramic substrate (five-layer laminate) made of crystallized glass having the same composition as the ceramic substrate of Embodiment 1, a low thermal expansion Kovar seal ring, and a ceramic or metal cap seal,
A 30 × 2.0 mm IC package was manufactured. Example 1
After an environmental test similar to that described above was performed, an airtightness test was performed, and the result was passed.

Example 3 A ceramic substrate (eight-layer laminate) made of crystallized glass having the same composition as that of the ceramic substrate of Example 1 was used.
A 132 grid pin grid array package of × 3.0 t was fabricated. After performing the same environmental test as in Example 1,
The result of the airtightness test was passed.

Example 4 In place of the crystallized glass of Example 1, an aluminum nitride sintered body, silicon carbide sintered body, mullite sintered body, silicon nitride sintered body or alumina sintered body having the properties shown in Table 3 Table 2 of Example 1 except that the body was made of a rectangular ceramic substrate. A bonding test substrate was manufactured under the same conditions as in Example 1, and the above three tests were performed.

As a result, cracks occurred only when a rectangular ceramic substrate made of an alumina sintered body was used, and the other parts were in a good joined state.

[0018]

As described above, by adopting the joined body of the present invention, it is possible to join metal fittings (input / output pins, seal rings, leads, etc.) to a low thermal expansion substrate such as glass / ceramic. It can be used for IC packages, multilayer boards, and the like.

[Table 3]

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ identification code FI H05K 1/03 610 H05K 1/03 610B (56) References JP-A-63-18648 (JP, A) JP-A-59-198741 (JP, A) JP-A-62-27518 (JP, A) JP-A-62-167833 (JP, A) JP-A-59-175521 (JP, A) JP-A-51-109479 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 37/02 B23K 1/19

Claims (5)

(57) [Claims] To 1. A 30 to 400 a predetermined portion of the ceramics substrate coefficient of thermal expansion ° C. is 1.5~5.0 × ^{10 -6} / ℃, sputtered layers in order from the ceramic substrate side
And a metal film having a multilayer structure in which a plating layer is laminated, and the metal film has a coefficient of thermal expansion of 1.5 to 5.0 ×
Conjugate ceramics substrate and the metal, characterized in that joined by 10 -6 ^/ ° C. metals solidus 650 ° C. or less of silver-based brazing material is. 2. The method according to claim 1, wherein the ceramic substrate is made of AlN, Si.
C, mullite, Si 3 _{N 4,} a ceramic composed mainly of cordierite, conjugate of claim 1, wherein comprising a glass ceramic or crystallized glass. 3. The joined body according to claim 1, wherein the metal is low thermal expansion Kovar. 4. The joined body according to claim 1, wherein the silver-based brazing material is an Ag—Cu—In alloy. Wherein said metal film, Ti-sputtered film from the ceramic substrate side in this order, Mo sputtered film, Cu sputtered film, to claims 1 to 4 Cu plating and Ni plating forms a multi-layer structure laminated The conjugate of the above.