JPH0365034B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a wiring board and a method for manufacturing the same,
In particular, the present invention relates to a multilayer wiring board for hybrid ICs and a method for manufacturing the same.

(Conventional technology) In recent years, with the increasing demand for electronic devices to be smaller and lighter, more multifunctional, faster, and more reliable, IC chips, resistors, and capacitors are being mounted on multilayer wiring boards made of ceramics such as alumina. Hybrid ICs, which are equipped with a large number of chip components and are hermetically sealed with a metal cap, are being widely used.

Ceramic multilayer wiring boards used in this hybrid IC are usually manufactured using the green sheet method.
It is manufactured by a method such as a thick film method or a thick film/thin film hybrid method.

However, such ceramic multilayer wiring boards are made of ceramics with a relatively large dielectric constant (ε) (ε=8 to 10) or crystallized glass (ε=9 to 10).
20), the stray capacitance of the wiring cannot be kept low, which hinders the high-speed operation of the mounted elements.

In order to deal with such problems, copper-polyimide multilayer wiring boards have recently been developed as wiring boards for mounting high-speed devices. As shown in FIG. 4, this wiring board has a structure in which a thin film conductor pattern 2 with a thickness of approximately 1 μm to 10 μm and a polyimide layer 3 are laminated on a ceramic substrate 1, and is manufactured as follows. ing.

That is, after forming a thin film of two or three types of conductors with copper as the main conductor on the entire surface of the ceramic substrate 1 by vapor deposition or sputtering, unnecessary parts are etched by a method such as photolithography to form the thin film conductor pattern 2. It is manufactured by repeating the first step and the second step of spin-coating and drying the polyimide resin, and then forming a through hole 4 for electrically connecting the upper and lower conductor patterns 2 by photolithography. .

And copper produced by such a thin film method -
In polyimide multilayer wiring boards, the dielectric constant of the polyimide resin that constitutes the insulator layer is extremely low (ε=3 to
4) Moreover, since the conductor pattern 2 is made of copper, which has a lower electrical resistance than other metals,
It has the advantage that the mounted elements can be operated at high speed.

(Problems to be solved by the invention) However, in such a wiring board,
Since polyimide resin has hygroscopic properties,
When a hybrid IC is manufactured by mounting an IC chip or the like and hermetically sealing it with a metal cap or the like, moisture will enter the mounting area inside the metal cap from the direction of the thickness of the polyimide layer 3.

This moisture caused problems such as short circuits in multilayer wiring due to migration, corrosion of ICs and wires, and short circuits due to condensation during temperature cycle tests.

The present invention was made to solve these problems, and is intended for use in hybrid ICs that have improved moisture resistance, prevents moisture from entering hermetically sealed areas, and are highly reliable and capable of high-speed operation. The purpose of the present invention is to provide a multilayer wiring board and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) The wiring board of the present invention includes a ceramic substrate and a low dielectric constant insulating material disposed at the center of a predetermined surface of the ceramic substrate as an insulator layer. a multilayer wiring section having system conductor patterns in multiple layers; an input/output pad formed at a peripheral portion of a predetermined surface of the ceramic substrate at a distance from the multilayer wiring section; and the input/output pad and the multilayer wiring section. A conductive wiring pattern disposed between the pads and having one end electrically connected to the input/output pad and the other end electrically connected to the terminal of the multilayer wiring section, and the multilayer wiring covering at least a part of the conductive wiring pattern, respectively. an insulator layer made of a moisture-resistant material formed in an annular shape on a predetermined surface of the ceramic substrate so as to surround the section; an annular conductor layer formed on the insulator layer; and a conductive cap, the base of which is attached to the annular conductive layer so as to cover it.

The manufacturing method also includes a step of forming a conductive wiring pattern on a predetermined surface of a ceramic substrate, with one end facing the periphery and the other end facing the center, and a step of forming a conductive wiring pattern on a predetermined surface of the ceramic substrate, covering at least a part of the conductive wiring pattern. and a step of forming an annular insulating layer made of crystallized glass so as to surround a central portion of a predetermined surface of the ceramic substrate, and a step of forming an annular conductive layer on the insulating layer by a thick film method. , a multilayer wiring section having a polyimide resin insulating layer at the center of a predetermined surface of the ceramic substrate, and a multilayer Cu-based conductor pattern whose terminal is connected to the other end of the conductor wiring pattern; Upper layer Cu
forming an input/output pad electrically connected to at least one end of the conductor wiring pattern simultaneously with the system conductor pattern by a thin film method; It is characterized in that it consists of a step of attaching it to the layer.

(Function) In the wiring board and the manufacturing method thereof of the present invention, the conductive wiring pattern and the annular conductor layer for electrical connection with the internal wiring are formed by a thick film method, and the conductive wiring pattern and the annular conductor layer are formed inside the annular conductor layer. A multilayer wiring section is provided on a ceramic substrate using a thin film method using a low dielectric constant insulating material as an insulating layer and having Cu-based conductor patterns in multiple layers.

Therefore, by mounting elements such as IC chips on a multilayer wiring element, a hybrid IC capable of high-speed operation can be obtained.

Furthermore, by attaching a metal cap to the annular conductor layer, the multilayer wiring section is hermetically sealed and does not come into direct contact with the outside air. Moreover, the insulator layer outside the annular conductor layer is made of ceramic or Constructed of crystallized glass, moisture does not penetrate in the thickness direction, so short-circuit corrosion accidents do not occur, making it a highly reliable hybrid.
IC is obtained.

Furthermore, since Cu-based input/output pads are formed on the exposed portions of the conductive wiring pattern using a thin film method, input/output leads, etc. can be easily fixed onto these pads.

Further, in a wiring board in which an annular conductor layer serving as a seal ring pattern is printed and formed using a thick film conductor paste having particularly good solder wettability, it is easy to weld metal caps with solder.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 and FIG. 2 are a perspective view and an enlarged sectional view of essential parts, respectively, showing an embodiment of the wiring board of the present invention.

In these figures, reference numeral 5 indicates a substrate made of ceramic such as alumina, and on the periphery of the surface of the ceramic substrate 5, there are a plurality of relatively short conductor patterns 6 each extending toward the center of the substrate. They are each formed by the thick film method shown below.

That is, these short thick film conductor patterns 6
For example, CU paste, Ag-Pt paste, Au-
Pt paste. Su− such as Ag−Pd paste
A thick film conductor paste that has good wettability with Pb-based solder and slow diffusion rate with this solder is used for 5~
It is formed by screen printing to a thickness of 20 μm, followed by drying and baking.

Further, on the short thick film conductor pattern 6 formed in this way, a ring-shaped insulating layer 7 is printed with crystallized glass paste and has a width such that both ends thereof are exposed and only the central part is covered. It is formed by drying and firing. Further, on this ring-shaped insulating layer 7, a ring-shaped conductor pattern 8 having a similar shape and slightly narrower width is formed by printing, drying, and baking the above-mentioned thick film conductor paste. It is formed.

Furthermore, on the surface of the ceramic substrate 5 inside such a ring-shaped thick film conductor pattern 8, there is a thickness consisting of two or three types of conductors with copper as the main conductor.
A copper-polyimide multilayer wiring section 11 is provided in which a thin film conductor pattern 9 of about 1 .mu.m to 10 .mu.m and a polyimide layer 10 of approximately the same thickness are alternately laminated by a thin film method as described below.

In other words, this multilayer wiring section 11 is constructed by first disposing two or three types of conductors with copper as the main conductor, for example, on the ceramic substrate 5 inside the ring-shaped conductor pattern 8.
Cr/Cu, Ti/Cu, Cr/Cu/Cr, Ti/Cu/Cr,
After forming a thin film by vapor depositing or sputtering a conductor such as Cr/Cu/Au, Ti/Cu/Au, etc., the first layer thin film conductor pattern 9 is formed by etching unnecessary parts using photolithography. do. The first layer thin film conductor pattern 9 is formed so that its end 12 overlaps the entire inner end of the short thick film conductor pattern 6, and the short thick film conductor pattern 6 and the multilayer The conductor pattern of the wiring section 11 is configured to be electrically connected.

Thin film conductor pattern 9 formed in this way
A polyimide resin, which is an organic material, is spin-coated thereon and dried and cured to form a polyimide layer 10, and then etched by photolithography to form through holes 13 for electrically connecting between the conductor patterns 9. do.

These steps are repeated to alternately stack a predetermined number of thin film conductor patterns 9 and polyimide layers 10, and finally, the uppermost layer thin film conductor pattern 9 is formed as shown below.

That is, in the uppermost layer, two or three types of conductors with copper as the main conductor are deposited or sputtered on the entire surface of the substrate, and then this thin film conductor is etched to form an IC inside the ring-shaped thick film conductor pattern 8. active elements such as chips and resistors,
A plurality of die pads 14 for mounting passive elements such as capacitors, and a plurality of outer leads for electrically connecting the mounted active elements and the conductor pattern of the multilayer wiring section 11 via bonding wires. In addition to forming a bonding pad (OLB) 15, a short thick film conductor pattern 6 is formed.
A plurality of larger input/output conductor pads 16 are formed on the outer exposed portions of the pads.

Elements are usually mounted on the wiring board of the embodiment configured as described above in the following manner, thereby configuring a hybrid IC.

That is, as shown in FIG.
On the die pad 14 of No. 1, an IC chip 17, a resistor, etc. (not shown) are bonded with adhesive such as conductive epoxy 18, and between these IC chips 17 and OLB 15, Au wire or Electrical connection is made by a bonding wire 19 such as an Al wire. And a ring-shaped thick film conductor pattern 8
On top of the
A cap 20 made of a metal whose coefficient of thermal expansion is almost equal to that of ceramic is fixed with eutectic solder 21 such as Sn/Pb63/37 alloy, and the IC chip 1 is
The area in which the components 7 and the like are mounted is hermetically sealed with an inert gas 22 such as helium or nitrogen sealed therein.

Furthermore, input/output leads such as clip leads and input/output pins (not shown) are fixed onto the thin film input/output conductor pad 16 using eutectic solder or the like.

Therefore, in the hybrid IC constructed in this manner using the wiring board of the embodiment, the insulating layer of the multilayer wiring section 11 on which the IC chip 17 and the like are mounted has a dielectric constant lower than that of ceramic or crystallized glass. Since it is made of low-density polyimide resin, the stray capacitance of the wiring can be reduced, leading to faster operation.

Furthermore, the area in which the IC chip 17 and the like are mounted is hermetically sealed with a metal cap 20, and the insulating layer around the substrate exposed outside the metal cap 20 is made of moisture-resistant material. Since it is made of high-quality ceramic such as alumina and crystallized glass, moisture is completely prevented from entering the mounting area inside the metal cap 20, and migration, wire corrosion, dew condensation, etc. do not occur. Furthermore, a ring-shaped conductor pattern 8 that becomes a seal cylinder pattern is formed of a thick film of a conductor that has good wettability with solder, and a conductor that has good solderability is placed on the exposed part of the short thick-film conductor pattern 6. Since the thin film input/output conductor pad 16 is formed of two or three types of conductors with the main conductor as the main conductor, a hybrid IC with high fixing strength for the metal cap 20, input/output leads, etc. can be obtained.

[Effects of the Invention] As is clear from the above description, according to the wiring board and the method for manufacturing the same of the present invention, moisture does not infiltrate into the mounting area of the element which is hermetically sealed with a metal cap or the like. Therefore, short circuit corrosion accidents will not occur. Therefore, a hybrid IC with high reliability and capable of high-speed operation of the element can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 are a perspective view and an enlarged sectional view of the main parts of an embodiment of the wiring board of the present invention, respectively, and Fig. 3 is an enlarged view of the main parts of a hybrid IC constructed using the wiring board of the embodiment. 4 is a cross-sectional view of a conventional copper-polyimide multilayer wiring board. 5... Ceramic substrate, 6... Short thick film conductor pattern, 7... Ring-shaped insulator layer, 8... Ring-shaped thick film conductor pattern, 9... Thin film conductor pattern, 10... Polyimide layer, 11...Multilayer wiring part, 13...Through hole, 14...Die pad, 15...
...OLB, 17...IC chip, 20...metal cap, 21...solder.

Claims (1)

[Scope of Claims] 1. A ceramic substrate; a multilayer wiring section having a multilayered Cu-based conductor pattern with a low dielectric constant insulating material as an insulating layer disposed at the center of a predetermined surface of the ceramic substrate; an input/output pad formed on the periphery of a predetermined surface of the board at a distance from the multilayer wiring section; and an input/output pad disposed between the input/output pad and the multilayer wiring section, one end of which is an input/output pad, and the other end of which is an input/output pad. conductive wiring patterns each electrically connected to the terminals of the multilayer wiring section; and an annular pattern on a predetermined surface of the ceramic substrate so as to cover at least a portion of each of the conductive wiring patterns and to surround the multilayer wiring section. an insulator layer formed of a moisture-resistant material; an annular conductor layer formed on the insulator layer; and a base attached to the annular conductor layer so as to cover the multilayer wiring section. A wiring board comprising a conductive cap and the following. 2. The wiring board according to claim 1, wherein the ceramic substrate is a substrate made of alumina. 3 Cu-based conductor patterns include Cr/Cu, Ti/Cu,
The wiring board according to claim 1, which is Cr/Cu/Cr, Ti/Cu/Ti, Cr/Cu/Au, or Ti/Cu/Au. 4. Claim 1, wherein the end of the lowest layer of the Cu-based conductor pattern constituting the multilayer wiring section is superimposed on and electrically connected to the other end of the conductive wiring pattern. wiring board. 5. The wiring board according to claim 1, wherein the low dielectric constant insulating material is a polyimide resin. 6. The wiring board according to claim 1, wherein the moisture-resistant material is crystallized glass. 7. The wiring board according to claim 1, wherein the conductive cap is a metal cap. 8. The wiring board according to claim 1, wherein the annular conductive layer is a seal ring pattern for attaching a conductive cap. 9. Forming a conductive wiring pattern on a predetermined surface of the ceramic substrate with one end facing the periphery and the other end facing the center using a thick film method; forming an annular insulating layer made of crystallized glass so as to surround a central portion of a predetermined surface; forming an annular conductive layer on the insulating layer by a thick film method; A multilayer wiring section having a polyimide resin as an insulating layer in the center of a predetermined surface and a Cu-based conductor pattern in multiple layers whose terminals are connected to the other end of the conductor wiring pattern, and a Cu-based conductor pattern on the top layer of this multilayer wiring section. At the same time, forming an input/output pad electrically connected to at least one end of the conductor wiring pattern by a thin film method, and attaching a base of a conductive cap to the annular conductor layer so as to cover the multilayer wiring part. 1. A method for manufacturing a wiring board, comprising: a step of attaching the wiring board; 10 The process of forming the conductor wiring pattern and the annular conductor layer is performed by printing, drying, and baking a thick film conductor paste that has good solder wettability and a slow diffusion rate with solder. 9. The method for manufacturing a wiring board according to item 9. 11. The method of manufacturing a wiring board according to claim 9, wherein the step of forming the insulating layer is performed by printing, drying, and firing a thick film crystallized glass paste. 12 The process of forming a Cu-based conductor pattern is as follows:
Cr/Cu, Ti/Cu, Cr/Cu/Cr, Ti/Cu/Ti,
10. The method of manufacturing a wiring board according to claim 9, wherein a thin film of Cr/Cu/Au or Ti/Cu/Au is deposited or sputtered, and unnecessary portions are etched by photolithography. 13. The method of manufacturing a wiring board according to claim 9, wherein the step of forming the insulating layer of polyimide resin is performed by forming a thin film of polyimide resin by spin coating and etching by photolithography.