JPH03184396A - Structure for preventing swelling of polyimide layer on multi-layer wiring board - Google Patents

Abstract

PURPOSE:To prevent a polyimide layer from being swollen by forming a second conductor pattern on the polyimide layer, connected to a first conductor pattern through the side walls of through holes, and providing opening parts in the through holes for exposing part of the first conductor pattern. CONSTITUTION:An insulating substrate 22 including therein through holes 23 at predetermined portions thereof is formed, and conductor paste is printed and baked by printing means to form a first conductor pattern 25 and a third conductor pattern 30. Then, a photosensitive polyimide solution is deposited by spin-coating and the like and the polyimide solution is pre-baked to form polyimide films 33, 34. Further, transparent holes 27, 31 are provided and the polyimide films 33, 34 are cured to form polyimide layers 26, 32. Thereafter, conductor thin films 35, 36 are deposited on the surface and back of the board and unnecessary portions of the conductor thin films 35, 36 are removed to form a second conductor pattern 2a having therein an opening 37 and a fourth conductor pattern 33 having therein an opening 38.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to prevent the polyimide layer from swelling during the manufacturing process in a multilayer wiring board that is used in highly integrated hybrid ICs and uses polyimide as an interlayer insulating layer. an insulating substrate having a via hole in which a conductor is embedded; a first conductive pattern formed on the insulating substrate at the same time as the conductor; A polyimide layer having a through hole directly above the conductor and directly connected to each of the first conductor patterns, formed on the polyimide layer and connected to the first conductor pattern through the side surface of the through hole. The second conductor pattern has an opening in the through hole that exposes a part of the first conductor pattern, or a via in which a conductor is buried in the through hole. An insulating substrate having a hole, at least a first conductor pattern on the surface of the insulating substrate, and a first polyimide layer having a through hole communicating with a desired portion of the first conductor pattern.

A second conductor pattern communicating with the first conductor pattern through the through hole of the first polyimide layer, a second polyimide layer exposing a required portion of the second conductor pattern, and At least a third conductive pattern is provided on the back surface of the substrate, a third polyimide layer having a through hole communicating with a required portion of the third conductive pattern, and a third conductor formed through the through hole of the third polyimide layer. A fourth conductive pattern communicating with the pattern is provided, and the fourth conductive pattern formed after forming the third polyimide layer has a through hole in a location not facing the third conductive pattern. It is characterized by being formed from a conductive thin film.

[Industrial application field]

The present invention relates to a multilayer wiring board used for highly integrated hybrid ICs and the like, and in particular to a structure for preventing swelling of a polyimide layer formed as an insulating layer between the eyebrows.

[Conventional technology]

FIG. 6 is a sectional view of a main part of a multilayer wiring board according to the prior art.

In FIG. 6, a multilayer wiring board 1 has a first conductor pattern 5. A polyimide layer 6 having through holes 7 through which the first conductor pattern 5 is exposed at required portions. A second conductor pattern 8 connected to the first conductor pattern 5 is formed within the through hole 7, and the insulating substrate 2
A third conductor pattern 9. A polyimide layer 11 having through holes 10 through which third conductive patterns 9 are exposed at required portions. A fourth conductive pattern 12 connected to the third conductive pattern 9 is formed within the through hole 10.

In such a multilayer wiring board 1, when the conductor pattern 5.9 is printed, the conductor 4 and the conductor pattern 5.9
is simultaneously formed using a conductor paste (e.g. Ag Pd paste), but when the conductor pattern 5.9 is formed from a conductor thin film, a conductor paste (e.g. Cu paste) is used.
The conductor 4 to be used is prepared by filling the through holes 4 of the clean sheet with conductor paste and firing at the same time as the substrate 1.

The polyimide layers 6 and 11, which are generally two-layered and have a thickness of about 20 μm, are fired at a temperature of about 300'C or more.

In the process of manufacturing such a multilayer wiring board 1, in order to form the polyimide layer 13 as shown by the dashed line in FIG. As shown in FIG. 1, a conductor film 14 before forming a conductor pattern is used.

[Problem to be solved by the invention]

FIG. 7 is an explanatory diagram of a bulge in a polyimide layer in a conventional multilayer wiring board.

FIG. 7(A) shows a case where the conductor patterns 5 and 9 are formed by printing, and when the conductor patterns 5 and 9 formed on the front and back surfaces of the substrate 2 are printed, the conductor 4 is filled in the through hole 3. A cavity 15 as shown in the figure is likely to be formed, and when the residue of cleaning prior to the formation of the polyimide layer 6 is taken into the cavity 15, the residue is gasified during the firing of the polyimide layer 6 and becomes a part of the polyimide layer 6. There was a drawback that a bulge 16 was easily formed.

FIG. 7 (II+) shows a case where the conductor patterns 5 and 9 are formed of thin films, and prior to forming the conductor pattern 12, the conductor film 16 on which the conductor pattern 12 is formed and the conductor pattern 8 are electrically connected (via holes). ) check is used, gas and water vapor generated from the polyimide layer 11 during firing of the polyimide layer 13 cause the polyimide 111 to
There was a drawback that a bulge 17 was easily formed.

The purpose of the invention is to prevent bulges 16 and 17 from forming.

[Means to solve the problem]

According to FIG. 1 showing an embodiment of the present invention, the first means of the present invention includes an insulating substrate 22 having a via hole in which a conductor 24 is embedded in a through hole 23, and a conductor 24 formed on the insulating substrate 22 at the same time. a polyimide layer 26 covering the first conductor pattern 25 and having through holes 27 directly above the conductor 24 and directly communicating with each of the first conductor patterns 25; The second conductor pattern 29 formed on the through hole 26 and connected to the first conductor pattern 25 through the side surface of the through hole 27 includes:
A multilayer wiring board 2 characterized in that an opening for exposing a part of a first conductor pattern 25 is provided in a through hole 27.
It is 1.

According to FIG. 2 showing an embodiment of the second means of the present invention, an insulating substrate 42 has a via hole in which a conductor 44 is embedded in a through hole 43, and at least a first Conductor pattern 45. A first polyimide layer 4 having through holes 47 communicating with required parts of the first conductor pattern 45
6. A second conductor pattern 48 . communicates with the first conductor pattern 45 through a hole 47 in the first polyimide layer 46 . Second
A second polyimide layer 49 is provided to expose the required portions of the conductor pattern 50 .On the back surface of the insulating substrate 42 , at least a third conductor pattern 50 . Third conductor pattern 5
A third polyimide layer 51. At the through hole 52 of the third polyimide layer 51, the third
A fourth conductive pattern 53 communicating with the conductive pattern 50 of
is provided, and the fourth conductor pattern 53 formed after the third polyimide layer 51 is connected to the third conductor pattern 50.
A conductive thin film 54 having a through hole 55 in a location not facing the conductor thin film 54.
A multilayer wiring board 41 characterized in that it is formed from
It is.

[Effect]

According to the first means, even if a cavity is formed in the via-hole conductor of the insulating substrate and cleaning liquid residue is left behind in the cavity, gas and water vapor such as the residue are removed from the polyimide layer that directly communicates with the conductor. Since the polyimide layer is removed from the through hole and the opening provided in the second conductor pattern, no bulge is formed in the polyimide layer.

Further, according to the second means, gas and water vapor generated from the second polyimide layer during firing of the third polyimide layer are removed through the through holes provided in the conductive thin film, and
This prevents bulges from forming in the polyimide layer.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multilayer wiring board having a polyimide layer bulge prevention structure according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the main parts of a multilayer wiring board according to the first embodiment of the present invention, FIG. 2 is a sectional view showing the main parts of the multilayer wiring board according to the second embodiment of the invention, and FIG. The figure is a main process diagram of the multilayer wiring board shown in Fig. 1, Fig. 4 is a main process diagram of the multilayer wiring board shown in Fig. 2, and Fig. 5 is a plan view of the fifth conductive thin film shown in Fig. 4. be.

In FIG. 1, the multilayer wiring board 21 has a conductor 2 in the through hole 23.
An insulating substrate with a via hole formed by burying 4 (
A printed first conductor pattern 25. A polyimide layer 26 having through holes 27 directly above each conductor 24 and communicating directly with the first conductor pattern 25 . A second conductor pattern 29 made of a thin film is formed so as to pass through the side surface of the through hole 27 and be connected to the first conductor pattern 25 at a required portion.

The conductor 24, which is formed by filling the through hole 23 with conductor paste, is formed by printing and burning in the same process as the first conductor pattern 25.

The two second conductor patterns have an opening that passes through the side surface of the through hole 27 and is connected to the first conductor pattern 25, exposing a part of the first conductor pattern 25 inside the through hole 27. 3
7 is formed.

A third conductive pattern 30 is printed on the back surface of the insulating substrate 22. Through hole 3 that communicates directly with at least each conductor 24
1. Polyimide layer 32. Through holes 31 in required parts
The fourth conductor pattern 30 is connected to the third conductor pattern 30 through the side surface of the conductor pattern 30.
A conductor pattern 33 is formed.

The fourth conductor pattern 33 has an opening 3 that passes through the side surface of the through hole 31 and is connected to the third conductor pattern 30, exposing a part of the third conductor pattern 30 inside the through hole 31.
8 is formed.

In the multilayer wiring board 21 configured in this way, even if a cavity 15 as shown in FIG. 7 is formed in the conductor 24,
Gas and water vapor generated from the cavity 15 are passed through the through holes 27.
31 or through openings 37.38,
The polyimide layer 26.32 has a bulge 1 as shown in FIG.
I can no longer do 6.

Hereinafter, the main manufacturing steps of the multilayer wiring board 21 will be explained using FIG. 3.

In FIG. 3(A), an insulating substrate 22 having through holes 23 in predetermined portions is prepared.

In FIG. 3 (II+), a conductor paste is printed and fired by a printing means to form a conductor 24. first conductor pattern 25,
A third conductor pattern 30 is formed.

In FIG. 3(C), a photosensitive polyimide liquid is applied using a spin cord or the like, and the polyimide liquid is prebaked at, for example, 130'C for 30 minutes to form a polyimide film 3.
3.34 is formed.

Next, as shown in FIG. 3(d), through holes 27 and 31 are formed and then cured to form polyimide layers 26 and 32.

Thereafter, conductive thin films 35 and 36 are deposited on the front and back surfaces as shown in FIG. A second conductor pattern 29 having an opening 38 and a fourth conductor pattern 33 having an opening 38 are formed.

The table on the next page compares the failure rate investigated for the multilayer wiring board 21 with the failure rate according to the prior art. However, in the samples according to the present invention and the prior art, Ag Pd paste was used as the printing conductor paste, and the polyimide layer was prebaked at 130 degrees for 30 minutes and then at 300 degrees for 30 minutes.

After curing at 400 degrees for 30 minutes, the conductive pattern forming thin film deposited on the polyimide layer is made of two layers: chrome and copper.
In addition to the layered structure, the through hole 27 formed in the polyimide layer of the multilayer wiring board 21 has a diameter of 0.2 mm+.

In the above table, after polyimide curing and thermal shock test, the test was conducted on good products from the previous process, and the thermal shock test
A temperature cycle of 1000 degrees to 125 degrees was performed.

And, for the sample configured according to the present invention, -55
I added 1000 temperature cycles from ℃ to 125℃,
The defective rate thereafter was also 0%.

In FIG. 2, the multilayer wiring board 41 has a conductor 4 in the through hole 43.
An insulating substrate with a via hole formed by burying 4 (
A first conductor pattern 45 made of a thin film is formed on the surface of the ceramic substrate 42. A first polyimide layer 46 having a through hole 47 exposing a predetermined portion of the first conductor pattern 45.
A second conductor pattern 48 made of a thin film is connected to the first conductor pattern 45 within the through hole 47 . A second polyimide layer 49 is formed to expose a predetermined portion of the second conductive pattern 48.

The conductor 44 is a through hole 43 made in the insulating substrate 42 before firing.
is filled with a conductive paste and fired together with the insulating substrate 42.

A third conductive pattern 50 made of a thin film is formed on the back surface of the insulating substrate 42. A third solid iron layer 51 having a through hole 52 exposing a predetermined portion of the third conductor pattern 50.
A fourth conductor pattern connected to the third conductor pattern 50 within the through hole 52
A conductor pattern 53 is formed.

As shown in FIG. 5, a large number of through holes 55 with a diameter of about 200 μm, for example, are formed in the conductor thin film 54 (thin film indicated by broken lines in the figure) before the fourth conductor pattern 53 is formed. The third conductor pattern 50 is provided without impairing the formation of the third conductor pattern 50 and at a location not facing the third conductor pattern 50.

The fourth conductive pattern 53 is formed by forming the polyimide layer 49 and removing unnecessary parts of the conductive thin film 54 after completing a continuity test between the conductive thin film 54 and each second conductive pattern 48. Become.

In the multilayer wiring board 41 configured in this manner, even if gas and water vapor are generated from the polyimide layer 51 to which the conductive thin film 54 is applied during firing of the polyimide N49, they are removed through the through holes 55, and the polyimide layer 51 A bulge 17 as shown in FIG. 7 will no longer be formed.

Hereinafter, the main manufacturing steps of the multilayer wiring board 41 will be explained using FIG. 4.

In FIG. 4(a), an insulating substrate 41 with a conductor 44 co-fired in a through hole 43 is manufactured.

In FIG. 4 (El), after a conductive thin film 56 is deposited on the front and back surfaces of the insulating substrate 41, unnecessary parts of the conductive thin film 56 are removed as shown in FIG. 4 (c), and the conductive patterns 45 and 56 are
0 is formed.

In FIG. 4 (=), the polyimide layer 4 after firing is completed.
6 and 51 are formed.

In FIG. 40), a thin conductive film 57 is deposited over the polyimide layers 46 and 51, respectively.

Next, as shown in FIG. 4(f), an unnecessary portion of the conductive thin film 57 deposited on the polyimide layer 46 is removed to form a conductive pattern 48, and an unnecessary portion of the conductive thin film 57 deposited on the polyimide layer 51 is removed. is removed to form a conductive thin film 54 with a large number of through holes 55.

Next, as shown in FIG. 4(g), a fired polyimide layer 49 is formed, and each conductor pattern 48 and conductor film 54 are formed.
After completing the continuity test with the conductive film 54, unnecessary portions of the conductive thin film 54 are removed to form a conductive pattern 53, as shown in FIG. 4(H).

〔Effect of the invention〕

As explained above, according to the first means of the present invention as explained using FIG. 1 and FIG. Gases, such as the residue, and water vapor are removed from the through holes in the polyimide layer that communicate directly with the conductor and the openings in the second conductor layer, so that the polyimide layer is prevented from swelling.

Furthermore, as explained using FIGS. 2 and 4, according to the second means of the present invention, gas and water vapor generated from the second polyimide layer during firing of the third polyimide layer are transferred to the conductive thin film. It is removed through the provided through hole, and no bulge is formed in the second voluminous layer.

As a result, the manufacturing yield and reliability of a multilayer wiring board using a polyimide layer as an insulating layer between the eyebrows has been improved.

[Brief explanation of drawings]

1 shows the main parts of a multilayer wiring board according to the first embodiment of the present invention, FIG. 2 shows the main parts of the multilayer wiring board according to the second embodiment of the invention, and FIG. 3 shows the multilayer wiring board shown in FIG. 1. Fig. 4 is a main process diagram of the multilayer wiring board shown in Fig. 2, Fig. 5 is a plan view of the fifth conductive thin film shown in Fig. 4, and Fig. 6 is a diagram of the conventional wiring board. Main parts of a multilayer wiring board, FIG. 7 is an explanatory diagram of the bulge of a polyimide layer in a conventional multilayer wiring board. In the figure, 21.41 is a multilayer wiring board, 22.42 is an insulating substrate, 23 and 43 are through holes of via holes, 24.44 is a conductor of via holes, 25.45 is a first conductor pattern, and 26 is a polyimide layer; 27 is a through hole in the polyimide layer; 29.48 is a second conductor pattern; 37.38 is an opening; 46 is a first polyimide layer; 47 is a through hole in the first polyimide layer; 2 polyimide layer, 50 is the third conductor pattern, 51 is the third polyimide layer, 52 is the through hole of the third polyimide layer, 53 is the fourth conductor pattern, 54 is the conductor thin film, 55 is the conductor thin film A drilled through hole is shown. Figure 1 shows the master's process of sewing and removing the needles. Figure 3 (-5r).
Figure 4

Claims (2)

[Claims] (1) An insulating substrate (22) having a via hole in which a conductor (24) is embedded in a through hole (23), and a first insulating substrate (22) having a via hole in which a conductor (24) is embedded in the through hole (23); a conductor pattern (25), and a through hole (27) that covers the first conductor pattern (25) and directly communicates with each of the first conductor patterns (25) at least directly above the conductor (24). Polyimide layer (
26), a second conductor pattern (29) formed on the polyimide layer (26) and connected to the first conductor pattern (25) through the side surface of the through hole (27); Prevention of swelling of a polyimide layer in a multilayer wiring board, characterized in that openings (37, 38) are provided in the through hole (27) to expose a part of the first conductor pattern (25). structure. (2) an insulating substrate (42) having a via hole in which a conductor (44) is embedded in the through hole (43);
) at least a first conductor pattern (45),
a first polyimide layer (46) having a through hole (47) communicating with a required portion of the first conductor pattern (45);
A second conductor pattern (4) communicates with the first conductor pattern (45) through a through hole (47) in the polyimide layer (46).
8) A second polyimide layer (49) is provided that exposes a necessary portion of the second conductor pattern (48), and at least a third conductor pattern (50) is provided on the back surface of the insulating substrate (42). , a third polyimide layer (51) having a through hole (52) communicating with a required portion of the third conductor pattern (50).
), a fourth conductor pattern (53) is provided which communicates with the third conductor pattern (50) through the through hole (52) of the third polyimide layer (51); 51) The fourth conductor pattern (53) formed after the formation is similar to the third conductor pattern (53).
A polyimide layer bulge prevention structure in a multilayer wiring board, characterized in that it is formed from a conductive thin film (54) with a through hole (55) formed at a location not facing the polyimide layer (50).