JPH0558678B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a wiring board comprising a semiconductor device mounting section and a wiring electrode section for guiding circuits from the semiconductor device.

(Prior Art) Conventionally, as shown in FIG. 3a, wiring is made up of a semiconductor device mounting portion 12 on a substrate 11 and a wiring electrode portion 13 that leads a circuit from the semiconductor device mounted on the semiconductor device mounting portion 12. On the board 14,
Semiconductor device mounting portion 12 of wiring electrode portion 13
The electrode portion 13a near the wire requires fine wiring and also needs to be usable for wire bonding, etc., so the entire wiring electrode portion 13 is made of Au. The method for creating the Au wiring electrode section 13 is as follows:
Conventional methods such as a screen printing method, a combination of a screen printing method and an etching method, and an Au resinate method can be used.

(Problems to be Solved by the Invention) However, Au is expensive, and if the entire wiring electrode part 13 is made of Au, there are problems in that the wiring board becomes expensive, it is impossible to solder, and the conductor resistance becomes high. Ta.

In order to solve this problem, the Au wiring electrode section 13
It is also possible to replace it with other inexpensive wiring patterns such as Cu, but with these cheap metals,
In particular, there were problems in that it was not possible to form a necessary fine pattern on the electrode portion 13a, and it was not possible to carry out wire bonding or the like.

Therefore, it is conceivable to form the wiring pattern in the electrode part 13a part using Au, and to form the other parts with other metals such as Cu, but in this case, as shown in FIG. 3b, the Au electrode If the Cu thick film electrode part 13 is formed by, for example, a screen printing method after forming the part 13a, Au may be diffused into the Cu due to the Kirkendall effect during firing of the Cu thick film electrode part 13, causing a disconnection 15. It was a lot. Furthermore, after forming the Cu thick film electrode part 13 on the whole, it is also possible to form the electrode part 13a on a predetermined part by electroless Au plating via electroless Ni plating, but the protrusion of the plating may cause a fine pattern. In addition, there was a problem that the Cu thick film electrode portion 13 was eroded by the plating solution and the adhesive strength was reduced to about 1/2.

An object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing a wiring board that is low cost, can be soldered, has low conductor resistance, and can be easily wire bonded and die bonded. It is something to do.

(Means for Solving the Problems) The method for manufacturing a wiring board of the present invention includes a semiconductor device mounting portion and a circuit leading from the semiconductor device.
A method for manufacturing a wiring board in which an Au electrode part and a Cu thick film electrode part that leads a circuit from the Au electrode part through a connection part are provided on a substrate, including a step of forming the Au electrode part, and a screen printing method. The process consists of a step of forming a pattern and then firing it in an inert atmosphere to form a Cu thick film electrode part, and a process of firing the conductive paste in an inert atmosphere of 700°C or less to form a connection part. This is a characteristic feature.

(Function) In the above structure, after forming the Au electrode section in advance, the Cu thick film electrode section is formed, and then an inert conductive paste is used between these Au electrode sections and the Cu thick film electrode section. to form a connection. As the conductor paste, it is preferable to use a Cu thick film conductor paste that can be sintered at low temperatures or a Ni conductor paste that can be fired in an inert atmosphere, and the following effects can be obtained.

(1) Since the amount of Au used is reduced, wiring boards can be obtained at low cost.

(2) Since the Au electrode part and the Cu thick film electrode part are connected by a connecting part and firing is performed at a relatively low temperature, disconnections caused by diffusion of Au into Cu due to the Kirkendall effect can be effectively prevented. can be lost.

(3) Since the Au electrode part is formed, wire bonding and die bonding can be easily performed.

(4) Since the connecting portion can be fired in an inert atmosphere and at a low temperature, the Cu thick film electrode portion will not be oxidized.

(5) Soldering is possible because a Cu thick film electrode part is provided.

(6) Since the wiring pattern is formed with a thick Cu film,
Low conductor resistance.

(Example) FIGS. 1a and 1b are a diagram showing the structure of an example of a wiring board obtained by the manufacturing method of the present invention, and an enlarged diagram showing the connection part thereof, respectively. In FIG. 1a, a wiring board 1 of the present invention has a semiconductor device mounting portion 3 on which a semiconductor device such as an LSI is mounted on a substrate 2 made of alumina or the like, and a semiconductor device mounting portion 3 in the vicinity of the semiconductor device mounting portion 3 has a semiconductor device mounting portion 3 on which a semiconductor device such as an LSI is mounted. A plurality of Au electrode parts 4 that guide the circuit, and these Au electrode parts 4
It is configured by providing a Cu thick film electrode section 6 that leads the circuit from the electrode section 4 through the connection section 5.

As shown in the enlarged view of FIG. 1b, the connecting portion 5 is
If the tip of the Au electrode section 4 and the tip of the Cu thick film electrode section 6 are separated by, for example, about 200 μm in consideration of printing accuracy, the Kirkendall effect between Au and Cu can be completely eliminated, thereby preventing wire breakage. This is preferable because it can be effectively prevented. However, in the present invention, even if the tip of the Au electrode section 4 and the tip of the Cu thick film electrode section 6 overlap, disconnection can be prevented because the connection section 5 is provided.

FIG. 2 is a flowchart showing an example of the method for manufacturing a wiring board according to the present invention. First, a pattern is formed by a conventionally known screen printing method, a method combining screen printing and etching, a thin film etching method, etc., and then baked as necessary.
Form an Au electrode part on the substrate. Next, after pattern-printing the Cu thick film conductor paste by screen printing method, the paste is printed at 850° C. in an inert atmosphere such as a nitrogen atmosphere.
A Cu thick film electrode part is formed by firing at a temperature of ~950°C.

Next, a pattern of low-temperature sinterable Cu thick-film conductor paste is printed between the Au electrode part and the Cu thick-film electrode part by screen printing, and the paste is then heated at 550 to 700°C in an inert atmosphere such as a nitrogen atmosphere. The connection is formed by firing at a temperature.

In addition, according to another method, there is a layer between the Au electrode part and the Cu thick film electrode part that can be fired in an inert atmosphere.
After pattern-printing the Ni conductor paste by screen printing, it is fired at a temperature of 550 to 700°C in an inert atmosphere to form a connection part.

Finally, a protective layer is provided on the surface of the substrate, if necessary, to obtain the wiring board of the present invention.

The results of an evaluation test on the wiring board of the present invention manufactured by the method described above are shown in the fourth section.
Shown in Figures a and b. As can be seen from the results shown in FIGS. 4a and 4b, the wiring board obtained by the present invention was able to reduce the conductor resistance value to about half that of the conventional product without impairing wire bonding properties.

The present invention is not limited to the embodiments described above, and can be modified and changed in many ways. For example, although an example of the firing temperature was specifically shown in the above embodiment, it is clear that the firing temperature is not limited to this temperature.

(Effects of the Invention) As is clear from the above description, according to the method for manufacturing a wiring board of the present invention, after forming an Au electrode portion, a Cu thick film electrode portion is formed, and further, these Au electrode portions and a Cu thick film electrode portion are formed. A wiring board that is low cost, can be soldered, has low conductor resistance, and is easy to wire bond and die bond because the specified connection part with the membrane electrode part is formed by a specified firing process. can be obtained.

[Brief explanation of the drawing]

FIGS. 1a and 1b are diagrams showing the structure of an example of a wiring board obtained by the manufacturing method of the present invention and an enlarged view of the connection parts thereof, and FIG. 2 is an example of the manufacturing method of the wiring board of the present invention. FIGS. 3a and 3b are flowcharts showing the structure of an example of a wiring board obtained by the conventional manufacturing method and an enlarged view of its connection parts, and FIGS. FIG. 3 is a diagram showing comparison data between the obtained wiring board and a conventional product. DESCRIPTION OF SYMBOLS 1... Wiring board, 2... Substrate, 3... Semiconductor device mounting part, 4... Au electrode part, 5... Connection part,
6...Cu thick film electrode part.

Claims (1)

[Claims] 1. A method for manufacturing a wiring board in which a semiconductor device mounting part, an Au electrode part that leads a circuit from the semiconductor device, and a Cu thick film electrode part that leads a circuit from this Au electrode part via a connection part are provided on a substrate. In,
A process of forming an Au electrode part, a process of forming a pattern by screen printing method and baking it in an inert atmosphere to form a Cu thick film electrode part, and a process of baking the conductive paste in an inert atmosphere at 700℃ or less. 1. A method for manufacturing a wiring board, comprising the step of: forming a connection portion using a wafer.