JPH011268A - ceramic circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A.6 Object of the Invention Industrial Application Field The present invention relates to a ceramic multilayer wiring board used in the electronic industry such as consumer products and computers.

BACKGROUND ART Conventionally, wiring boards using ceramics as an insulator have been used as circuit boards for electronic devices. A typical example is a conductor-co-fired ceramic wiring board that uses W or No as a wiring conductor and is fired in a reducing atmosphere to prevent the conductor from oxidizing. However, since this board uses metal or MO for the conductor, the conduction resistance is 1.
It is high at 0 to 20m ohm/mouth, and requires post-processing of N1 plating and Au plating to enable mounting of semiconductor elements such as LSI and soldering of parts.

? [In order to solve these problems, conductive materials with low conduction resistance such as Ag, Au, and Cu are used.These are hereinafter referred to as low melting point metals.]The temperature below the melting point of these materials is A low-temperature fired ceramic wiring board has been developed in which a conductor is simultaneously fired using a ceramic material which can be fired at (800 to 1100'C) as an insulator.
In the case of a conventional alumina ceramics board, the input/output terminal (■10 terminal) is a conductor band of No or -.
After that, Kovar or 4.2 alloy pins or leads were brazed using Ag-Cu brazing material. However, in the case of low-temperature fired substrates, since low melting point metals such as Heg, Au, and C:U are mainly used as conductors, these metals have inferior heat resistance than - and MO, so they are It was not possible to obtain strength due to dissolution. Therefore, in the case of low-temperature firing, pins and leads for I10 terminals are generally connected with solder.
After soldering, only processes that can be performed at low temperatures can be performed. For example, if wire bonding of Si chips is performed using thermosonics, the substrate temperature will rise to over 200°C. When solder is used in this way, subsequent working methods are limited in terms of temperature, which greatly reduces practicality. As a countermeasure to this problem, JP-A-Sho Go-1787
No. 61 discloses a method in which a pad having a metal film belonging to group 8 of the periodic table is placed on a titanium thin film and a pin is brazed thereon. In this method, the content of Au in the brazing material is 8
Since it uses a large amount of Au-9n brazing material (0%), it is hard and brittle, has lower strength than Ag-Cu brazing material, and is expensive.

Another known method is to form a thin film on the surface of an alumina substrate and perform 1-1 brazing using Ag-Cu solder, but the alumina substrate used when co-firing Mo and W conductors generally has a rough surface. It was difficult to form a thin film.

Problems to be Solved by the Invention The present invention is characterized by low temperature sintering with Ag, Au, and Cu-based conductors.
, (A to the metal pads connected to these conductors on the plate)
It is an object of the present invention to provide a ceramic circuit board in which pins and leads at the I10 end and r-river are connected using a g-Cu type brazing material.

Means for Solving the Problems in the Structure of the Invention The present invention is based on a method for solving the problem of the structure of the invention. This is a ceramic circuit board characterized by a structure in which pins or leads for I10 terminals are bonded by a brazing material containing Cu.The low temperature fired board contains a large amount of glass component in its raw materials, so it has a good surface roughness. Advantages suitable for thin film formation.

4A, 5AJA, 8. of the periodic table as a metal layer. It is characterized by being made of IB metal and a combination of metals. Furthermore, PbO in ceramic plate material N1 is 1.
The brazing material is characterized by being processed in a neutral or 5-light atmosphere at a temperature of 600°C or higher.
The problem with the brazing I-1 method disclosed in Japanese Patent Application Laid-Open No. 178761 is that it uses a weak and expensive Au-5n material as the brazing filler metal. In the present invention, a strong and inexpensive Ag-Cu based brazing material is used as the brazing material. Ag-
Since a Cu-based brazing material is used, the brazing material processing temperature is higher than approximately 400° C. for an Au-3n-based brazing material. Ag
- Since the eutectic temperature of Gu is 779°C, the processing temperature of the brazing filler metal is higher than this. Although the treatment temperature can be lowered by adding the 3.4th component such as Zn, Bi, etc., the second treatment temperature is required to be 800° C. or higher. At this processing temperature, it is necessary to perform the brazing material treatment in a neutral or reducing atmosphere so that the Cu in the Ag--Cu solder does not oxidize. During this brazing filler metal treatment, if the ceramic substrate contains a PbO component, the neutral or Q-element atmosphere reduces the PbO and deteriorates the insulation properties of the substrate. Therefore, the PbO component of the ceramic substrate material should be less than 1z, preferably less than L5. In other words, the substrate to be used is (ultimately pb
Any material may be used as long as it does not contain o and can be fired at 800 to 1100° C. and has good surface roughness. Typical examples include borosilicate glass and several other oxides (such as Mg
O.

SrO, CaO, BaO, AI OK O, Na O,
Those made from a mixture of glass powder containing ZnO, Li2O, Zr2023'2 2, Tl02) and ceramic powder such as alumina, quartz, chromium oxide, mullite, cordierite, cordierite type, α
Some are made from crystallized glass powder that produces subodumene crystals. For example, Japanese Patent Application No. 59-110973, Japanese Patent Application No. 83725 filed by the present inventors,
Patent application No. Sho EiO-237458, Patent application No. Sho 6O-282E
No. i88 is an example of such materials, and these materials suitably contain 1% or less of PbO as an impurity. These substrates have a surface roughness Ra of 0.05 to 0.4 m and are suitable for this use. On the other hand, in the case of an alumina substrate used for recirculating firing of ordinary W and Mo conductors, Ra is 0.4 to 1. Op
-m, which may require polishing in some cases.

At the processing temperature of Ag-Cu brazing filler metal, the Ag, Au, and Cu conductors used in low-temperature fired substrates will dissolve into the brazing filler metal during the brazing process, resulting in a decrease in adhesive strength and damage to bottles and leads. The required adhesive strength cannot be obtained. In the present invention, the metal pad to be brazed is formed into a thin film made of a heat-resistant metal so that it can withstand Ag-C:U brazing processing, and it is also made of a thin film made of a heat-resistant metal, which has excellent adhesion to ceramics, or a thin film made of a heat-resistant metal. Combining metals with excellent wettability. The metals used for these thin films include 4A, 5A, and fliA on the periodic table.
, 8. Select from group IB.

Sputtering, deposition, and plating are used to form the thin film, but a thick film may be used for the outermost layer depending on the case.

FIG. 1 is an example of a conceptual diagram showing the present invention, in which an Ag-based conductor 15 is built into a ceramic substrate l, and a Si chip 7 and an Au conductor are mounted on the top surface.
Equipped with electrode 6. The bottom surface shows a specific example of the present invention in which 16 Ag-based conductors 15 in the built-in and through-holes and the cover pin 5 as the I10 terminal are connected by a Ti-No-Cu thin film 3 and an Ag-Cu solder 4. .

Example 1 A ceramic green sheet made of Cab-At O-5iO2-B203 glass powder and alumina powder
After printing a wiring pattern using g conductor paste, multiple sheets were laminated and bonded by thermocompression. Conductor connections between layers were made using conductor paste filled in through holes punched in the green sheet. After firing at 900°C, thin films were formed in the order shown in Figures 2-5. As shown in FIG. 2, a metal mask 8 is fixed on a fired substrate made of an Ag conductor 2 as a built-in conductor of a ceramic 7x 1 and set in a sputtering apparatus.

Next, after evacuation to 2 x 10-6 torr, Ar gas was introduced, and then Ti was continuously heated.9. Moto, Cu
In order of II, 0.1 body m, 1.0 w country, 2.
IIF seedlings were grown from the thin film of the same country (Figure 3). In this case 7
The first layer 9 is N to obtain adhesion with the ceramic 1.

Layer 10 is an extension of 71 layer 9 to Cu-Ag wax! This is to improve the wettability of the Cu layer 11 with the Ag--Cu brazing layer 13 in order to prevent fogging. After this, remove the mask (Figure 4)
, A is placed on a 15mmφ metal pad on a ceramic substrate.
850°C in nitrogen/hydrogen atmosphere using g-Cu wax
After processing for 10 minutes, a 0.35 mmφ bottle 12 was connected (FIG. 5). The bottle broke when the adhesive strength of the bottle was 5 kg or more. Further, the strength did not change even after 100 heat cycles at 150°C@R, r4-40°C.

Similar results were obtained when a 4.270-inch bottle was used. However, if the amount of brazing filler metal was too large, the strength would decrease, which was not preferable. Further, the connection between the Ag conductor 2 and the thin film in the through-hole portion 16 shown in FIG. 5 was good, and no problems occurred even after the heat cycle. Similar results were obtained when the Ti layer 9 was made of Or, and when the No layer 10 was made of W, Nb, or Ta. Also, the part of the Cu layer 11 is N
i.

Similar results were obtained using Ag or Pd.

Example 2 A laminate obtained in the same manner as in Example 1 using Ag-Pd conductor paste (13) on a ceramic green sheet made of CaO-MgO-At203-5iO, -8203-based glass powder and alumina powder. It was fired at 950'O (Figure 6). After this, 0.1 g each of Ti9, Mo1O, and Cu1l was applied to the surface of the side where the pin is connected in this order.
A thin film with a thickness of 1.0 gm, 2.0 gra was formed by sputtering, and then a mask of resist 14 was formed on the side of the thin film using photolithography. Although the subsequent steps are not shown, the Cu film is
The Mo film was converted to KOH-3[Fe
The thin film was removed by etching with (CM)e]5 aqueous solution to obtain a band of 1.5 amφ. A 0.35 mm diameter Kovar pin was brazed onto the remaining pad using an Ag-Cu solder in a nitrogen reducing atmosphere at 850°C. The adhesion strength of the pin was generally 5 kg or more, and the pin broke. 150'
Similar results were obtained after 100 heat cycles at 40° C. for R and T. Similar results were also obtained when using a 4.270-inch pin. Similar results were obtained when the Ti layer 9 was made of Cr and when the No layer 10 was made of W, Nb, or Ta. Also, the Gulf's 1st Kuhi is Ag,
The same thing happened when Pd or Ni was used.

Example 3 Si080%, B,0312% remaining 7)ly f
3 +) 50% glass powder with an average particle size of 2 gm consisting of metals and oxides of alkaline earth metals and 1 liter
A ceramic insulator multilayer wiring board with a built-in Ag-Pd conductor was created in the same manner as in Example 2 using a mixed powder for ceramic insulators consisting of 30% alumina powder of 54 m uniform grain size and 20x chromium oxide powder. did. At this time, the firing was performed in an oxidizing atmosphere under the conditions of maintaining 950' CIHr. Further, in the same manner as in Example 1, a 1tν film pad of 1,5111 IIlφ consisting of each layer of Ti, Mo, and Cu was formed, and a pin of 0.35 mmφ was soldered using Ag-Cu solder. The pin was attached (1, the strength was 5 kg or more), and the pin was cut with (2). Further, the strength did not change even after 100 cycles of heat cycles of 150°C hand R and T5-4o°C. Also 4.
Similar results were obtained when using 270 i pins. However, if the amount of brazing filler metal was too large, the strength would decrease, which was not desirable. Also, the Ag of the through hole shown in Figure 2
- The connection between the Pd conductor and the thin film was good, and no problems occurred even after the heat cycle described in 1-. Similar results were obtained when the T1 part was set to Or, and when the No part was set to Nb or Ta. Similar results were obtained even when the Cu portion was replaced with Ni, Ag, or Pd.

C. Effects of the invention It is now possible to braze I10 bottles and leads to plates using Ag-Cu based brazing materials, which could not be used in the past. Obtaining pins and leads at low cost has become IIf fk.Also, the surface roughness of the low temperature fired substrate used for this purpose is I1
The 8-striped structure has the advantage of forming a thin film for soldering pins and leads.

[Brief explanation of the drawing]

FIG. 1 shows an example of a schematic diagram incorporating the invention. 2 to 6 show partially enlarged views of an example of the manufacturing method of the present invention. Figure 2: Metal mask preliminary determination Figure 3: Metal thin film formation Figure 4: Metal mask removed Figure 5: Ag-C:U pin bonding Figure 6: Thin 1
19F- resist formation l Ceramin Kusno, (Plate 2 Ag conductor 3 Ti-No
-Cu thin 1i! 24 Ag-C: u wax 5 Cover pin 13 Au electrode 7 Si chip 8 Metal mask 9 Ti film 10 No IIQ II C
U film 12 pins + 3 Ag-Pd conductor 14
Resist film 15 Ag-based conductor 16 Through hole 17
Au-3iJ% crystal special 1;1 Applicant: Narumi Seito Co., Ltd. Figure 1 Figure 2 Figure 4 Figure 5

Claims (4)

[Claims] (1) A pin or lead for an I/0 terminal is placed on a metal layer formed by a thin film method on a substrate that is fired at 800 to 1100°C and has circuit wiring made of a low-melting point metal conductor inside, using wax containing Cu. A ceramic circuit board characterized by having a structure bonded by materials. (2) Metal layer is 4A, 5A, 6A, 8, 1B of the periodic table
The ceramic circuit board according to claim 1, characterized in that the ceramic circuit board is made of a group metal and a combination thereof. (3) The ceramic circuit board according to claim 1, wherein the content of lead oxide in the ceramic material is 1% by weight or less. (4) The ceramic circuit board according to claim 1, wherein the brazing treatment is performed in a neutral or reducing atmosphere of 600° C. or higher.