JPH0722717A - Printed wiring board - Google Patents

Abstract

PURPOSE:To prevent sagging from being generated at the circumferential part of the opening of an insulation substrate when laminating a thin insulation substrate and a substrate for mounting. CONSTITUTION:In a bonding substrate 1 with a device hole 2 for mounting a bare chip and a printed wiring board P which is applied via a lower substrate 3 and an adhesive 4, the width of a conductor pattern 9 formed on the application surface of the bonding substrate 1 is enlarged and the circumference of the device hole 2 is buried by the conductor pattern 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board,
More specifically, the present invention relates to a bonded printed wiring board having a mounting recess for mounting an electronic component such as a bare chip.

[0002]

2. Description of the Related Art In this type of printed wiring board, a bonding substrate (insulating substrate) 31 having a device hole 30 and a lower substrate 32 have an adhesive 33 as shown in FIG.
It is configured to be bonded via. The upper surface of the lower substrate 32 and the device hole 30 form a bare chip mounting recess. In addition, the conductor pattern 3 is formed on both surfaces (the back surface is shown in FIG. 6) of the bonding substrate 31.
4, 35 are respectively formed, and both conductor patterns 3
4, 35 are electrically connected via a through hole 36.

Conventionally, in the above-mentioned printed wiring board, a relatively thick insulating base material having a thickness of 0.5 mm or more is used for the bonding substrate 31. However, in recent years, there has been a strong demand for a lighter, thinner, shorter and smaller printed circuit board and a higher density, so that attempts have been made to manufacture a printed circuit board having a thin bonding board 31.

[0004]

However, when the thickness is 0.
There are the following problems when a thin printed wiring board is manufactured using the bonding substrate 31 of 2 mm or less.

In the manufacturing process of the printed wiring board, the adhesive 33 is applied to the bonding surface of the bonding substrate 31 on which the conductor patterns 34 and 35 are formed, and the device hole 30 is formed by hollowing out the place where the bare chip is mounted. After that, the lower substrate 32 and the lower substrate 32 are attached by pressing.
Then, this laminating press is performed in a state where a stainless steel plate is brought into contact with the lower base material 32 side and the bonding substrate 31 is covered with a cushion material (illustrated by a chain double-dashed line in FIG. 5) 37. However, the thin bonding substrate 31
When the pad is pressed by the cushion material 37, as shown in FIG. 7, the portion where the conductor pattern 35 is not formed is dented and unevenness is generated on the whole. Then, in the peripheral portion of the device hole 30 where the conductor pattern is not formed on the bonding surface, sagging occurs toward the lower substrate 32 side. For this reason, the conductor pattern 3 existing in the portion
The bonding pad 38 of No. 5 is deformed and hangs down. When a bare chip is mounted in this state and wire bonding is performed with Au wires, the bonding pads 38 are deformed, so that the Au wires cannot be connected to the pads 38 and mounting defects frequently occur. There is a problem of doing.

The present invention has been made to solve the above problems, and an object thereof is to sag on the peripheral portion of the opening of the insulating substrate when the thin insulating substrate and the mounting substrate are bonded together. Another object of the present invention is to provide a printed wiring board that can prevent the occurrence of

[0007]

In order to solve the above-mentioned problems, in the invention according to claim 1, an insulating substrate having conductor patterns formed on both surfaces and an opening for mounting an electronic component, A printed wiring board in which a mounting substrate on which components are mounted is bonded via an adhesive, and at least the peripheral portion of the opening of the bonding surface of the insulating substrate,
A reinforcing pattern was formed.

According to the second aspect of the invention, an insulating substrate having conductor patterns formed on both sides and an opening for mounting an electronic component is formed, and a mounting substrate for mounting the electronic component is adhesive. In the printed wiring board bonded via the insulating substrate, the width of the conductor pattern formed on at least the peripheral edge of the opening of the bonding surface of the insulating substrate is widened to fill the peripheral edge of the opening with the conductor pattern.

[0009]

In the invention described in claim 1, since the reinforcing pattern is formed at least on the peripheral portion of the opening of the bonding surface of the insulating substrate, the thin insulating substrate and the mounting substrate are separated from each other. When laminating with a press, it is possible to prevent dripping from occurring in the peripheral portion of the opening. Therefore, the bonding pad formed on the peripheral portion is not deformed,
Wire bonding with electronic components such as bare chips is reliably performed.

Further, according to the second aspect of the invention, since the peripheral portion of the opening is filled by expanding the width of the conductor pattern formed on the bonding surface side, the peripheral portion at the time of bonding is similar to the above. No one will be struck. Further, the area where a pattern having a sagging prevention effect can be formed is increased as compared with the case where a reinforcing pattern independent of the conductor pattern is formed.

[0011]

EXAMPLE 1 Example 1 embodying the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a printed wiring board P includes a bonding substrate 1 as an insulating substrate having a device hole 2 as an opening, and a lower substrate as a mounting substrate for mounting an IC chip (bare chip) (not shown). 3 and 3 are pasted together via an adhesive 4. A bare chip mounting recess is formed by the upper surface of the lower substrate 3 and the device hole 2.

As shown in FIG. 2, a conductor pattern 5 is formed on the surface of the bonding substrate 1 opposite to the bonding surface. The conductor pattern 5 includes a plurality of bonding pads 6 arranged in four directions around the peripheral edge of the device hole 2.
And a wiring 7 connected to the bonding pad 6 and a through hole 8 connected to a part of the wiring 7.

As shown in FIG. 3, a part of the wiring 7 and the through hole 8 are formed on the bonding surface of the bonding substrate 1.
A plurality of conductor patterns 9 connected to each other are formed. The conductor pattern 9 has a gap G between adjacent conductor patterns 9 and a gap G between the open ends of the device holes 2.
Is constant (0.15 mm to 0.2 mm in this embodiment) so that the width of the conductor pattern 9 is widened. Therefore, the conductor pattern 9 fills most of the bonding surface of the bonding substrate 1 including the peripheral portion of the device hole 2. In addition to the role of the circuit, the conductor pattern 9 has a role of reinforcing the bonding substrate 1, that is, a role of preventing the deformation of the bonding substrate 1 when the bonding substrate 1 and the lower substrate 3 are bonded by a press.

The printed wiring board P constructed as described above
In the case of manufacturing, the adhesive 4 is applied to the bonding surface of the bonding substrate 1 on which the conductor patterns 5 and 9 and the through holes 8 are formed on both sides, and the device hole 2 is formed by hollowing out the place where the bare chip is mounted. To do. Next, the bonding substrate 1 and the lower substrate 3 are laminated and pressed. The press brings a stainless plate into contact with the surface facing the lower substrate 3,
The bonding substrate 1 is covered with a cushion material (illustrated by a chain double-dashed line in FIG. 1) 10 on the opposite side to the bonding surface. At this time, even if the bonding substrate 1 is pressed by the cushion material 10, since the conductor pattern 9 is formed on most of the bonding substrate 1, the pressing force acts almost uniformly on the entire surface of the bonding substrate 1 to form the uneven shape. There is no distortion. As a result, the sagging of the bonding substrate 1 at the peripheral portion of the device hole 2 is reliably prevented, and the bonding pad 6 is not deformed.

As described above, in the printed wiring board P of this embodiment, since the conductor pattern 9 is formed wide, distortion of the bonding substrate 1 at the time of bonding and occurrence of sagging of the peripheral portion of the device hole 2 occur. Can be prevented. Therefore, the bonding pad 6 existing in the peripheral portion of the device hole 2 is not deformed, and the bare chip mounted in the mounting recess and the bonding pad 6 are not deformed.
Wire bonding with can be reliably performed. As a result, it is possible to prevent defective mounting of the bare chip on the printed wiring board P.

Further, since the bonding board 1 is not distorted or sagging, the printed wiring board P can be kept smooth. Further, since only the conductor pattern 9 connected to the through hole 8 is formed on the bonding surface of the bonding substrate 1, it is only necessary to design the conductor pattern 9 in consideration of the position where the through hole 8 is formed. Well, the pattern can be designed freely and easily.

Further, in the case of this embodiment, since only the originally necessary pattern exists, it is not necessary to provide an extra plating lead when, for example, gold plating is required. [Second Embodiment] Next, a second embodiment will be described. This embodiment is different in that the conductor pattern 9 is not formed wide but a separate pattern is provided.

As shown in FIG. 4, a part of the wiring 7 and the through hole 8 are formed on the bonding surface of the bonding substrate 1.
A plurality of conductor patterns 11 connected to each other are formed. Further, in addition to the conductor pattern 11, a reinforcing pattern 12 is formed around the entire periphery of the device hole 2. The reinforcing pattern 12 is for reinforcing the bonding substrate 1 and does not serve as a circuit.

The bonding substrate 1 configured as described above is pressed against the cushion material 10 at the time of bonding, but since the peripheral portion of the device hole 2 is reinforced by the pattern 12, sagging occurs at that portion. There is no such thing.

The present invention is not limited to the above-mentioned embodiments, but may be modified as follows without departing from the gist of the present invention. (1) In the first embodiment, only the conductor pattern 9 adjacent to the opening end of the device hole 2 is wide and the gap G is large.
May be formed to be constant. Further, the conductor pattern 9 may be formed up to the opening end without providing the gap G.

(2) In the second embodiment, the pattern 12 is formed all around the peripheral edge of the device hole 2.
It does not have to be the entire circumference. Also, a plurality of patterns 12 may be formed.

(3) The wide conductor pattern 9 and the reinforcing pattern 12 may be formed in combination.

[0024]

As described above in detail, according to the present invention, when the thin insulating substrate and the mounting substrate are attached to each other, it is possible to prevent sagging from occurring in the peripheral portion of the opening of the insulating substrate. It has an excellent effect that

According to the second aspect of the present invention, the area where the pattern having the sagging prevention function can be formed is increased, and the distortion of the entire printed wiring board is further reduced.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view showing a printed wiring board of Example 1 of the present invention.

FIG. 2 is a schematic partial plan view showing the surface of the bonding substrate opposite to the bonding surface.

FIG. 3 is likewise a schematic partial plan view showing a bonding surface of a bonding substrate.

FIG. 4 is a schematic partial plan view showing a bonding surface of a bonding substrate of Example 2.

FIG. 5 is a partial schematic cross-sectional view showing a conventional printed wiring board.

FIG. 6 is likewise a schematic partial plan view showing a bonding surface of a bonding substrate.

FIG. 7 is also a partial schematic cross-sectional view showing a state where the bonding substrate is distorted by pressing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bonding substrate as an insulating substrate, 2 ... Device hole as an opening, 3 ... Lower substrate as a mounting substrate, 4 ... Adhesive agent, 5 ... Conductor pattern, 9 ... Conductor pattern, 12 ... Pattern, P ... Print Wiring board.

Claims (2)

[Claims] 1. A printed wiring board in which a conductive pattern is formed on both sides and an opening for mounting an electronic component is formed, and a mounting substrate on which an electronic component is mounted are bonded together with an adhesive. A printed wiring board, wherein a reinforcing pattern is formed on at least a peripheral portion of the opening of the bonding surface of the insulating substrate. 2. A printed wiring board in which a conductive pattern is formed on both sides and an opening for mounting an electronic component is formed, and a mounting substrate on which an electronic component is mounted are bonded together with an adhesive. The printed wiring board is characterized in that the width of a conductor pattern formed on at least the peripheral portion of the opening of the bonding surface of the insulating substrate is expanded and the peripheral edge of the opening is filled with the conductor pattern. .