JPH08307045A - Wiring board - Google Patents

Abstract

PURPOSE: To provide a wiring board which is applicable to the mounting of a semiconductor chip with a small spacing between electrodes. CONSTITUTION: An opening 11A, that is almost equal in size to or larger than the surface of a semiconductor chip to be opposed to the substrate 2 of a wiring board, is formed in the resist film 11 formed on the substrate 2 in a position where the semiconductor chip is mounted. This constitution makes it possible to surely bond the electrodes on the semiconductor chip to respective electrodes correspondingly formed on the substrate 2 through bumps, regardless of bump height and the height of the resist film 11. Thus a wiring board applicable to the mounting of a semiconductor chip with a small spacing between electrodes may be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board, and is suitable for application to, for example, a wiring board for flip chip (F / C) mounting.

[0002]

2. Description of the Related Art Conventionally, as one mounting method for mounting an IC chip on a wiring board, bumps are formed on respective electrodes (pads) of the IC chip and the IC chip is mounted on the wiring board by a face-down method. There is a so-called flip-chip mounting method in which each pad of the IC chip and the corresponding electrode (land) of the wiring substrate are joined by melting each bump after positioning and mounting.

The wiring board used for such flip chip mounting is usually constructed as shown in FIG. 3, and corresponds to the pad position of the IC chip to be mounted on one surface of the substrate 2 made of glass epoxy material or the like. Thus, a plurality of lands 3 are provided. Also, on one surface of the substrate 2,
A resist film 4 made of an insulating material is applied so as to avoid the periphery of each land 3 of the substrate 2 for the purpose of limiting the soldering area and ensuring insulation, and thus the frame shape of the resist film 4 thus formed. As shown in FIG. 4, the pads (not shown) of the IC chip 5 to be mounted and the wiring board 1 are passed through the openings 4A of the wiring board 1.
The corresponding land 3 can be bonded via the bump 6.

[0004]

By the way, in recent years, the spacing between the pads of the IC chip 5 has become narrower due to the high density mounting of electronic components on a wiring board. In this case, when the IC chip 5 having a narrow pad interval is mounted on the wiring board 1 by the flip chip mounting method, the wiring board 1
In order to prevent shorts from being generated between the respective lands 3 (and between the respective pads of the IC chip 5), the size of the bumps 6 for joining the respective pads of the IC chip 5 and the corresponding lands 3 of the wiring board 1 is conventionally set. Need to be smaller than.

Therefore, generally, in the IC chip 5 having a narrow pad interval, the height of the bump 6 formed on each pad tends to be inevitably lowered. However, in the conventional wiring board 1 for flip chip mounting, the thickness of the resist film 4 is about 20 [μm], so that if the height of the bump 6 of the IC chip 5 is made lower, the thickness of the resist film 4 becomes smaller. The bumps 6 may exceed the height of the bumps 6, and as a result, the bumps 6 formed on the pads of the IC chip 5 with the lower surface of the IC chip 5 in contact with the upper surface of the resist film 4.
Cannot contact the corresponding land 3 of the wiring board 1 and the IC chip 6 cannot be mounted on the wiring board 1 (that is, I
There is a possibility that each pad of the C-chip 5 cannot be reliably and accurately joined to the corresponding land 3 of the wiring board 1 via the bump 6.

The present invention has been made in consideration of the above points, and an object thereof is to propose a wiring board that can be mounted on an IC chip having a narrow electrode interval.

[0007]

In order to solve such a problem, in the present invention, the semiconductor chip is formed on a resist film deposited on the substrate in correspondence with the mounting position of the semiconductor chip mounted on the wiring substrate. An opening portion that is substantially equal to or larger than the surface facing the substrate is provided.

[0008]

By providing an opening in the resist film which is substantially equal to or larger than the surface of the semiconductor chip facing the substrate, the semiconductor chip is fitted into the opening of the resist film on the substrate. Can be mounted and implemented. Therefore, regardless of the height of the bumps for joining the electrodes of the semiconductor chip and the corresponding electrodes of the wiring board and the height of the resist film, the electrodes of the semiconductor chip and the wirings corresponding to these electrodes are provided. The electrodes of the substrate can be reliably bonded to the electrodes provided on the substrate via the bumps.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

1 and 2 in which parts corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, 10 denotes a wiring board for flip-chip mounting according to the embodiment as a whole, and an insulating material is provided on the board 2. The resist film 11 is formed. In this case, the resist film 11 is provided with an opening 11A at a mounting position of the IC chip 5 and having substantially the same size as the surface of the IC chip 5 facing the substrate 2, and thus the IC chip 5 to be mounted is mounted. The opening 11 of the resist film 11
It is designed so that it can be completely fitted into A.

In the above structure, the wiring board 10 can be mounted by mounting the IC chip 5 to be mounted so as to be fitted into the opening 11A of the resist film 11 provided at the mounting position. Therefore, the bumps 6 formed on the respective pads of the IC chip 5 can be reliably brought into contact with and bonded to the corresponding land 3 regardless of the height thereof or the thickness of the resist film 11.
Even the IC chip 5 having a small pad interval can be mounted surely and accurately.

In practice, for example, when a gold stud bump is used as the bump 6, the pad pitch of the IC chip 5 is 150.
When the thickness is less than [μm], when the IC chip 5 is mounted in the conventional wiring board 1 (FIG. 3), the resist film 4 (thickness of about 20 [μm]) below the IC chip 5 allows the IC chip 5 to be removed.
It has been confirmed by an experiment that it is difficult to surely mount (that is, it is difficult to bring the bumps 5 formed on each pad of the IC chip 5 into contact with the corresponding lands 3 of the wiring board 1 to join them). In the wiring board 10 of the example, such an IC chip 5 can be mounted surely and accurately.

According to the above structure, an opening having a size substantially equal to the surface of the IC chip 5 facing the substrate 2 is formed at the mounting position of the IC chip 5 on the resist film 11 deposited on the substrate 2. By forming the portion 11A, the IC chip 5 having a small pad interval can be surely mounted, and thus a wiring board that can be mounted to the IC chip having a narrow electrode interval can be realized.

In the above-described embodiment, the size of the resist film 11 deposited on the substrate 2 is substantially the same as the surface of the IC chip 5 facing the substrate 2 at the mounting position of the IC chip 5. However, the present invention is not limited to this, and the point is that an opening larger than the surface of the semiconductor chip facing the substrate can be completely fitted into the semiconductor chip to be mounted. If a portion is provided, the size of the opening 11A of the resist film 11 may be other than substantially the same size as the surface of the IC chip 5 facing the substrate 2.

[0015]

As described above, according to the present invention, with respect to the resist film deposited on the substrate of the wiring substrate, the mounting position of the semiconductor chip is almost the same as the surface of the semiconductor chip facing the substrate or By providing an opening larger than the facing surface, each electrode of the semiconductor chip and each electrode provided on the substrate corresponding to each of these electrodes are provided with bump heights and resist film heights. Regardless of this, it is possible to surely bond the bumps via the bumps, and thus it is possible to realize a wiring board which can be mounted on an IC chip having a narrow pitch between electrodes.

[Brief description of drawings]

FIG. 1 is a top view showing a configuration of a wiring board for flip-chip mounting according to an embodiment.

FIG. 2 is a cross-sectional view showing how an IC chip is mounted on the wiring board shown in FIG.

FIG. 3 is a top view showing a configuration of a conventional wiring board for flip-chip mounting.

FIG. 4 is a cross-sectional view showing how an IC chip is mounted on the wiring board shown in FIG.

[Explanation of symbols]

2 ... Board, 3 ... Land, 5 ... IC chip, 6 ...
Bump, 10 ... Wiring board, 11 ... Resist film, 11
A: Opening.

Claims (2)

[Claims] 1. A substrate having a land formed on one surface corresponding to electrode positions of a semiconductor chip to be mounted, and a resist film made of an insulating material deposited on the one surface of the substrate, In a wiring board for mounting the semiconductor chip by bonding the electrodes of the semiconductor chip to the corresponding lands of the substrate via bumps, the semiconductor is mounted at the mounting position of the semiconductor chip with respect to the resist film. A wiring board having an opening substantially equal to or larger than the surface of the chip facing the substrate. 2. The bump is a gold-stud bump, and the semiconductor chip has a pitch of the electrode of 150 [μm].
The wiring board according to claim 1, wherein: