JPH08181239A - Circuit board for mounting flip-chip - Google Patents

Abstract

PURPOSE: To obtain a circuit board, in which there is no defective section in resin infection, by forming section, in which a resist pattern is not formed, extending over approximately the whole region of a semiconductor-element mounting area on the surface layer of the circuit board. CONSTITUTION: Conductor circuit patterns 2 and electrode sections 3 for connection with a semiconductor element are shaped onto the board surface of a circuit board 1 mainly comprising alumina, and these conductor circuit patterns 2 and electrode sections 3 for connection are connected electrically. A resist 4 is printed on the board surface of the circuit board 1 through screen printing, and cured in the thickness of approximately 20μm. A section not coated with the resist 4 is formed in approximately the whole region of a semiconductor- element mounting area 5 on the surface layer of the circuit board 1. Accordingly, a clearance between the semiconductor element and the circuit board is expanded, thus preparing the circuit board, in which there is no detective section in inter-layer sealing-resin injection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor mounting circuit board on which a semiconductor device is flip-chip mounted, and more particularly to a resist pattern provided on the board.

[0002]

2. Description of the Related Art In recent years, with the demand for miniaturization of electronic equipment, high-density mounting of circuit modules has been desired, and circuit boards are progressing from double-sided wiring to multi-layer wiring, and active elements are also downsized. Further, semiconductor devices have been actively developed from conventional plastic molded products to bare chips, and recently flip chip mounting has been attracting attention as a method of bare chip mounting of semiconductor devices.

A conventional circuit board for flip-chip mounting will be described below. FIG. 4 is a plan view of a conventional semiconductor mounting circuit board, and FIG. 5 is taken along line BB of FIG. 4 when a semiconductor element is flip-chip mounted on the conventional semiconductor mounting circuit board shown in FIG. FIG. FIG.
In the above, the conductor circuit pattern 2 and the connecting electrode portion 3 for connecting the semiconductor element are formed on the substrate surface of the circuit board 1, and the conductor circuit pattern 2 and the connecting electrode portion 3 are electrically connected to each other. There is. Further, a resist 4 is applied on the entire surface of the substrate excluding the area of the connecting electrode portion 3 so as to cover them. In addition, 5 has shown the semiconductor element mounting area.

At the time of flip-chip mounting, as shown in FIG. 5, solder bumps 8 preliminarily printed using a mask on the bump electrodes 7 of the semiconductor element 6 and the connecting electrode portions 3 on the circuit board 1 are connected. Then, the semiconductor element 6 is placed on the circuit board 1. After that, the solder bumps 8 are melted by a heat treatment such as reflow to connect them,
Further, the interlayer sealing resin 9 is injected into the gap between the semiconductor element 6 and the circuit board 1. In this state, the semiconductor chip 6 (usually, normally) is mounted, but if the interlayer sealing resin 9 is not sealed in a predetermined place, the semiconductor element 6 (usually,
Due to the difference in coefficient of thermal expansion between the LSI chip) and the circuit board 1, the semiconductor element 6 mounted on the flip chip may have a bad connection, and the reliability may be significantly deteriorated. In order to prevent this, it is general that the interlayer sealing resin 9 is tightly sealed to eliminate the difference in thermal expansion coefficient. As a method, the injection of the interlayer sealing resin 9 is inclined. It is performed on a hot plate by waiting until the interlayer sealing resin 9 oozes out around the semiconductor element 6, then lowering it from the hot plate and allowing it to stand to cure the interlayer sealing resin 9.

[0005]

However, in the above-described conventional configuration, when the flip-chip mounting is performed, the solder bump solder is melted, so that the solder bump diameter before connection is about 150 μm. The gap between the semiconductor element 6 and the circuit board 1 is as narrow as about 80 μm. Moreover,
Since the resist of about 20 μm is also applied to the lower part of the semiconductor element 6 on the surface layer of the circuit board 1, after all, the gap between the semiconductor element 6 and the circuit board 1 is only about 60 μm. . Therefore, when the semiconductor element 6 and the circuit board 1 are connected and then the interlayer sealing resin 9 is put into the gap, an injection failure such as air bubbles of the interlayer sealing resin 9 is entangled, and the reliability of the mounting body is reduced. There was a problem of remarkable deterioration.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a circuit board free from defective resin injection.

[0007]

In order to achieve the above object, the present invention provides a portion where a resist pattern is not formed over substantially the entire semiconductor element mounting area on the surface layer of the circuit board.

[0008]

According to the above structure, when the interlayer sealing resin is injected into the gap after connecting the semiconductor element and the circuit board, the gap between the semiconductor element and the circuit board is wide because there is no resist. In addition, the interlayer sealing resin for sealing becomes easy to enter, and since the gap is wide, the injection speed is increased and the workability is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of flip-chip mounting using the circuit board of the present invention will be described below with reference to the drawings. 1 is a plan view of a semiconductor mounting circuit board of the present invention, and FIG. 2 is a line AA of FIG. 1 when a semiconductor element is flip-chip mounted on the semiconductor mounting circuit board of the present invention. FIG. The same parts as those of the conventional semiconductor mounting circuit board are designated by the same reference numerals.

In FIGS. 1 and 2, an electrode portion 3 for connecting the conductor circuit pattern 2 and the semiconductor element 6 is formed on the substrate surface of the circuit board 1 containing alumina as a main component. The pattern 2 and the connecting electrode portion 3 are electrically connected. Also, a resist 4 is printed on the surface of the circuit board 1 by screen printing to reduce the film thickness.
Hardened to a thickness of about 20 μm. In the conventional substrate, only the connecting electrode portion 3 is exposed and the resist 4 is applied to all other portions, but in the present invention, as shown in FIG. 1, the semiconductor element mounting area on the surface layer of the circuit board 1 is mounted. The feature is that the resist 4 is not applied to substantially the entire area of 5.

A process of flip-chip mounting on the circuit board 1 configured as described above will be described. The solder bumps 8 printed in advance on the bump electrodes 7 of the semiconductor element 6 using a mask are aligned with the connection electrode portions 3 on the circuit board 1, and the semiconductor element 6 is mounted on the circuit board. Place. Then, when the solder bumps 8 and the connecting electrode portions 3 are brought into contact with each other and passed through a reflow furnace, the semiconductor elements 6 and the connecting electrode portions 3 are connected by melting the solder bumps 8. At this time, compared with the diameter of the solder bump before connection being about 150 μm, the solder of the solder bump 8 melts and spreads, so that the gap between the semiconductor element 6 and the circuit board 1 is about 80 μm. Next, in order to improve reliability, the interlayer sealing resin 9 is injected into the gap between the circuit board 1 and the semiconductor element 6 on a hot plate that is inclined. In this embodiment, since there is no resist 4 in the gap between the semiconductor element 6 and the surface of the circuit board 1, the film thickness is about 20 μm, which is wider than that of the conventional board. It is easy to perform, and a circuit board without resin injection defects can be produced. Moreover, since the interlayer sealing resin 9 is easily injected, the work efficiency is significantly improved. In this way, after waiting for the interlayer sealing resin 9 to seep around the semiconductor element 6, the interlayer sealing resin 9 is cured by lowering it from the hot plate and allowing it to stand.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals. In FIG. 3, 1
Is a circuit board, 2 is a conductor circuit pattern, 3 is an electrode portion for connecting to a semiconductor element, and 4 is a resist. The difference from the configuration of the first embodiment of FIG. 1 is that a resist dam 10 is formed on the inside of the chip of the connecting electrode portion 3 by a resist 4 having a width of about 200 μm. The resist dam 10 is not formed at the four corners adjacent to each other as shown in the figure. When flip-chip mounting is performed using this circuit board 1, the melted solder of the solder bumps 8 spreads over a certain area because the resist dam 10 is formed on the outer peripheral portion of the connecting electrode portion 3 on the chip inner side. In addition, since it is possible to prevent the semiconductor element 6 from sinking due to the spread of solder, it is possible to reduce the rate of narrowing the gap between the semiconductor element 6 and the circuit board 1. Moreover, since the resist dam 10 is not formed at the four corners adjacent to each other as described above, there is a gap here,
The interlayer sealing resin 9 can be injected from this gap portion, and since there is no resist 4 there, the interlayer sealing resin 9 is easily injected and the working efficiency is greatly improved.

[0013]

As described above, in the circuit board of the present invention, the gap between the semiconductor element and the circuit board is eliminated by providing the portion not coated with the resist on almost the entire area of the semiconductor element mounting area on the surface layer of the circuit board. It is possible to create a circuit board that does not spread and have a defective injection of the interlayer sealing resin. Moreover, since the gap between the semiconductor element and the circuit board is wide, the injection speed of the interlayer sealing resin is increased and the workability is improved.

[Brief description of drawings]

FIG. 1 is a plan view of a semiconductor mounting circuit board according to a first embodiment of the present invention.

FIG. 2A of FIG. 1 when a semiconductor element is flip-chip mounted on a semiconductor mounting circuit board according to an embodiment of the present invention.
FIG. 6 is a partial cross-sectional view taken along the line A.

FIG. 3 is a plan view of a semiconductor mounting circuit board according to a second embodiment of the present invention.

FIG. 4 is a plan view of a conventional semiconductor mounting circuit board.

5 is a partial cross-sectional view taken along line BB of FIG. 4 when a semiconductor element is flip-chip mounted on a conventional semiconductor mounting circuit board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Circuit board, 2 ... Conductor circuit pattern, 3 ... Connection electrode part, 4 ... Resist, 5 ... Semiconductor element mounting area, 6 ... Semiconductor element, 7 ... Bump electrode, 8 ... Solder bump, 9 ... Interlayer sealing Resin, 10 ... Resist dam.

Claims (1)

[Claims] 1. A flip-chip mounting circuit board for flip-chip mounting a semiconductor element in a semiconductor element mounting area on a surface layer of a circuit board on which a conductor circuit pattern is wired, wherein a resist pattern is formed over substantially the entire area of the semiconductor element mounting area. A circuit board for flip-chip mounting, characterized in that a portion not formed with is provided.