JP2001210674A - Mounting method of bare chip ic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable mounting of each bare chip IC on both faces of a circuit board, without having to increase man-hour in a circuit board, in which two or more bare chip ICs are mounted on a wiring board in a flip-chip method. SOLUTION: A bare chip IC 1 is mounted on the front face of a wiring board 2 while a bare chip IC 1' is mounted on the rear face of the wiring board 2. In this case, the circuit board with each bare chip IC is pressurized by using a stage 6 previously warmed and a pressurizing press previously warmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to two or more bare chip ICs having the same bonding pad coordinates.
The present invention relates to a flip chip type bare chip mounting method in which a certain load is applied to a bare chip IC using the same as a connection medium and connected to a wiring board.

[0002]

2. Description of the Related Art Flip chip mounting is a bare chip IC.
Is directly connected to the wiring board, which is very advantageous for high-density mounting.

[0003] One of the flip-chip mounting methods in which the man-hour is relatively simple is to provide a projection such as a stat bump on a bonding pad of a bare chip, and to provide an ACF and a conductive material between the bare chip IC and the substrate. The bare chip I arranged via a connection medium such as paste and further arranged as described above
There is a method of connecting the bare chip IC and the wiring board by applying a certain weight to the bonding pad of C for a certain time.

However, in the case of the above method, when the bare chip IC is pressed, the bare chip IC and the substrate need to be uniformly pressed. Therefore, the mounting component is not mounted on the back surface of the substrate on which the bare chip IC is mounted, and is flattened. There is a need.

For this reason, when a plurality of bare chip ICs are mounted, the mounting surface of the bare chip IC is generally unified.

The MCM embodiment described in the May 1997 issue of Nikkei Microdevices is an example in which five bare chip ICs are mounted, but the mounting surfaces of the bare chip ICs are unified on the same surface.

[0007]

In a circuit board on which bare chip ICs are flip-chip mounted by the above-described flip chip mounting method, when the mounting density is to be further increased, the bare chip ICs are mounted in order to effectively use the mounting area of the wiring board. It is necessary to mount bare chip ICs on both the front and back surfaces of the wiring board to be formed.

However, bare chip ICs are provided on both sides of the wiring board.
In the bare chip IC mounting process when mounting a chip, it is necessary to uniformly apply pressure to the bonding pad of the bare chip IC, so a flip chip mounting process is required for each bare chip IC mounting surface, and the bare chip mounting process increases. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit board on which two or more bare chip ICs having the same bonding pad coordinates are mounted, without significantly increasing the number of steps for mounting the bare chip, in the mounting areas on both surfaces of the front and back surfaces of the circuit board. Since the IC can be mounted, there is an effect that two or more bare chip ICs can be mounted at high density without increasing the number of man-hours.

[0010]

According to the present invention, a bare chip IC having the same bonding pad coordinates is mounted on both the front and back surfaces of a wiring substrate, and the bonding pad position of the bare chip IC mounted on the front surface is provided. The bare chip IC is arranged so that the bonding pad position of the bare chip IC arranged on the back surface is opposed to the bonding pad position via the wiring board, and the pressure during flip chip bonding is arranged on the back surface with one press Bare chip I
In a state where the insulating substrate for mounting the bare chip IC is sandwiched between C and the bare chip IC arranged on the front surface, a flip chip is pressed between the bare chip IC arranged on the front surface and the bare chip IC arranged on the back surface. Since the mounting is performed, the bare chip IC can be uniformly pressed onto the circuit board without increasing the number of steps, and the bare chip IC can be mounted on both sides of the circuit board.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of flip chip mounting of the ACF system using the composite wiring board mounting method of the present invention will be described below with reference to FIGS.

In the ACF method, the connection between the bare chip IC and the wiring board is generally performed by applying pressure to the bare chip IC and the substrate while applying heat to the ACF.

FIG. 1 is a sectional view of a circuit board on which a bare chip IC according to the present invention is mounted and arranged.

FIG. 2 shows a method for connecting bare chip ICs arranged on the wiring board in FIG. FIG. 3 shows a completed circuit board obtained by connecting the bare chip ICs arranged on the wiring board in FIG. 1 in the manner shown in FIG.

In FIG. 1, ACF tapes 4 and 4 'as connection media are attached to a wiring substrate having a wiring pattern 3 formed on an insulating substrate 5 such as a glass epoxy substrate, a ceramic substrate or the like, and the same bonding pad coordinates are set. The bare chip ICs having the stat bumps 2 and 2 ′ provided on the bare chip ICs 1 and 1 ′ are arranged on the back side and the front side of the wiring board so as to face each other via the wiring board.

As described above, the bare chip IC having the same bonding pad coordinates on the front and back surfaces with respect to the wiring board, respectively.
Are arranged so as to face each other, the pressing force for connecting the wiring board and the bare chip IC is equal to the stat bump 2 provided on the bare chip IC 1 provided on the front surface and the stat bump 2 'provided on the bare chip IC 1' provided on the back surface. It is weighted between the wiring boards sandwiched between them.

In FIG. 2, the stage 6 is pre-heated for ACF connection so that the front surface of the bare chip IC placed on the wiring board in FIG. In FIG. 1, a pressurizing press device 7 with a heating device is arranged from the surface opposite to the back surface of the bare chip IC placed on the front surface or the back surface of the bare chip IC placed on the wiring substrate in FIG. , Bare chip I on the surface arranged on the wiring board in FIG.
By applying pressure with a certain load while heating from both sides of C1 and the bare chip IC 1 'arranged on the back surface, the bare chip IC arranged on the wiring substrate and the front surface and the bare chip IC arranged on the back surface can be flip-chip mounted.

FIG. 3 shows a circuit board completed by the method of the present invention by flip-chip mounting the bare chip IC arranged on the wiring board in FIG. 1 by the method of FIG.

In a circuit board on which two or more bare chip ICs having the same bonding pad coordinates are mounted by the above mounting method, the bare chip ICs can be flip-chip mounted on both sides of the wiring board without increasing the number of steps.

[0020]

As described above, according to the method of the present invention, in a circuit board on which two or more bare chip ICs having the same bonding pad coordinates are mounted, the same bonding pad coordinates can be used without greatly increasing the number of steps. Since the bare chip IC can be mounted on both sides of the circuit board, a high-density circuit board can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circuit board mounted on both front and back surfaces of a bare chip IC wiring board according to the present invention.

FIG. 2 is a cross-sectional view of a circuit board and a connection device arranged in the device for connecting FIG. 1;

FIG. 3 is a sectional view of a circuit board completed according to the present invention.

[Explanation of symbols]

1, 1 ': bare chip IC having the same bare chip pad coordinates, 2, 2': stat bump, 3, 3 ': wiring pattern, 4, 4': ACF, 5: insulating substrate, 6: mounting stage for flip chip , 7 ... Pressing press device for flip chip.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Morio Muramatsu 1410 Inada, Hitachinaka City, Ibaraki Pref. Digital Media Products Division, Hitachi, Ltd. F-term (reference) 5E336 AA04 AA14 BB02 BC31 CC31 CC58 EE05 EE07 5F044 KK10 LL07 LL09 PP15 PP19

Claims (1)

[Claims] 1. A wiring board comprising: a wiring pattern formed on an insulating substrate; two or more bare chip ICs having the same bonding pad coordinates; In a flip-chip mounting method in which a bare chip is mounted by pressing against a substrate, the mounting surfaces of the two or more bare chip ICs having the same bonding pad coordinates are arranged on the front and back surfaces of the wiring board and mounted on the front surface. The bare chip IC is arranged so that the bonding pad position of the bare chip IC and the bonding pad position of the bare chip IC arranged on the back face face each other via the wiring board, and the pressure during flip chip bonding is once. Between the bare chip IC placed on the back side and the bare chip IC placed on the front side by pressing In a state where the insulating substrate on which the bare chip IC is mounted is sandwiched therebetween, a flip chip mounting is performed by applying pressure between the bare chip IC arranged on the front surface and the bare chip IC arranged on the back surface. Implementation method.