JPH09162525A - Process for applying sealing resin to bare chip in flip chip mounting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for applying a sealing resin to a bare chip in a flip chip mounting method which has an excellent moisture resistance, durability and shock resistance and a high reliability to perform a resin sealing quickly and surely without any necessity of holding obliquely a printed wiring board in the case of the working of applying the sealing resin to the bare chip. SOLUTION: In a process for applying a sealing resin to a bare chip in a flip chip mounting method, exhausting the air present in the space between a bare chip 21 and a printed wiring board 22 for mounting the chip 21 thereon by an air sucking device 26 attached to a small-diameter through hole 22a, simultaneously with this, a sealing resin 24 is made to flow into the space to complete its application work after confirming its filling into the space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing resin coating process which is excellent in moisture resistance, durability and impact resistance in a flip chip mounting (hereinafter referred to as FC mounting) method.

[0002]

2. Description of the Related Art A conventional F / C mounting method has been performed in the following process sequence. (1) After the bare chip 1 is mounted on the printed wiring board 2 by soldering, thermocompression bonding, etc., the printed wiring board 2 on which the bare chip 1 is mounted is hot plate (or electric furnace).
3. Heat to 60-100 ° C. (2) While the printed wiring board 2 is being heated, the printed wiring board 2 on which the bare chip 1 is mounted is tilted (see θ in FIG. 8).
Indicates the tilt angle). (3) A required amount of the sealing resin 4 is dropped by a dispenser 5 on the upper side of the bare chip 1 of the printed wiring board 2 on which the bare chip 1 is mounted in the heated state (see FIG. 9). (4) The sealing resin 4 dropped on the printed wiring board 2 is transmitted to the bottom surface of the bare chip 1 by gravity, that is,
The bottom surface of the bare chip 1 was rotated and filled with resin only by the fluidity of the sealing resin 4 (see FIG. 10).

[0003]

However, in the step of applying the sealing resin in the above-mentioned F / C mounting method, the sealing resin flows by gravity on the inclined surface and wraps around to the lower part of the bare chip, so that the coating operation is long. There is a problem that it takes time.

Further, when the gap between the bare chip and the printed wiring board is small, or when a sealing resin having poor fluidity is used, the sealing resin is completely sealed between the bare chip and the printed wiring board. There was a case where it did not go around, and there were problems in terms of moisture resistance, durability and impact resistance.

Further, it is impossible to confirm whether or not the sealing resin has wrapped around to the lower surface of the bare chip 1 and is filled with it, unless the bare chip is peeled off. It is necessary to tilt the wiring board 2,
There is a problem that it is difficult to apply the encapsulating resin in the F / C mounting on a large printed wiring board.

The present invention has been made to solve the above problems, and an object thereof is to eliminate the need for inclining a printed wiring board to perform a sealing resin coating operation and to exhaust air. Provided is a bare chip sealing resin applying step in a highly reliable F / C mounting method in which the lower space of the bare chip is quickly resin-sealed by means, and which is excellent in moisture resistance, durability, and impact resistance. Especially.

[0007]

In order to achieve the above object, the present invention provides a method for applying a sealing resin to a bare chip in an FC mounting method, in which a bare chip and a printed wiring board on which the bare chip is mounted are mounted. At the same time as the air is discharged by an air discharge means such as a vacuum device, a step of filling the sealing resin and completing the sealing resin application work of the bare chip is provided.

According to this, since the small-diameter through hole is provided at the center of the area of the printed wiring board facing the bare chip, the sealing resin is quickly filled from this through hole and the printed wiring board is inclined. There is no need. Also,
It can be confirmed in the small-diameter through-hole that the sealing resin is filled, and the air mixed in the filled sealing resin is also removed at the same time as the filling.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are process diagrams as a first embodiment of the present invention. Figure 1 shows bare chip 11
FIG. 4 is an external perspective view showing a plurality of bumps 11a of spherical electrodes arranged around the lower surface thereof. FIG. 2 shows a printed wiring board 1 for mounting the bare chip 11.
2 is an external perspective view of FIG. 2, in which an FC mounting pad 13 is provided, and a small diameter through hole 12a is provided in the center thereof.

Next, work steps of the F / C mounting method according to the present invention will be described. First, a large number of minute spherical electrode bumps 11a are arranged around the lower surface of the bare chip 11 (FIG. 1). These bumps 11a are connected to the F.
After aligning with the C mounting pad 13 (FIG. 2), they are connected and mounted by soldering, thermocompression bonding or the like (FIG. 3).

After the bare chips 11 are mounted on the printed wiring board 12 by F / C, the sealing resin 14 is dropped and supplied around the bare chips 11 of the printed wiring board 12 by a dispenser 15 or the like (FIG. 4). The dropping supply of the sealing resin by the dispenser 15 or the like is performed in a container (not shown) space capable of making the resin sealing region a vacuum state, and the sealing resin is supplied to the periphery of the bare chip 11. Meanwhile, the inside of the container is evacuated. As the inside of the container approaches the vacuum state, the sealing resin around the bare chip 11 decreases, and in order to complement the decrease, the vacuum state progresses,
A sealing resin is supplied around the bear chip 11.

By doing so, the bare chip 11
A sufficient amount of sealing resin can be supplied around the area. Then, when the sealing resin can be confirmed from the small-diameter through hole 12a of the printed wiring board 12 below the bare chip 11, the vacuum state is stopped, and the F / C mounted sealing resin around the bare chip 11 is mounted. The supply of 14 is terminated. FIG. 5 is an external perspective view of the main part showing this state.

FIG. 6 shows a second embodiment of the encapsulation resin coating step in the F / C mounting method according to the present invention, which shows an apparatus for sucking air between the bare chip 21 and the printed wiring board 22. It is the principal part side sectional view shown. In this embodiment, the rubber nozzle 26a of the air suction device 26 is connected to the small-diameter through hole 22a to suck air in the direction of the arrow so that the bare chip 21 is dropped and supplied to the outer periphery of the bare chip 21 by a dispenser or the like (not shown). The sealing resin 24 is sucked into and filled between the printed wiring board 22 and F.
-The method of supplying the sealing resin to C mounting is shown. Then, according to this embodiment, when the sealing resin is confirmed by the suction part rubber aerosol 26a of the air suction device 26, the driving of the air suction device 26 may be stopped, which allows the sealing resin to be highly efficient. The lower space of the bear tip 22 is filled,
The desired effect can be obtained.

Further, FIG. 7 is a side sectional view showing the third embodiment of the present invention, showing a construction in which the sealing resin 34 is directly supplied to the FC mounting portion by a dispenser 37 or the like. In this case, first, the bare chip 31 is FC mounted on the printed wiring board 32. The dispenser 37 is inserted into the small-sized through hole 32a provided in the printed wiring board 32 below the bare chip 31 mounted by F / C, and the sealing resin is supplied by compressed air to fill the area around the bare chip 31 with the sealing resin. After confirming this, the supply of the sealing resin is stopped. According to this process, the vacuum resin generator as in the first embodiment is not required, and the process of applying the sealing resin to the bare chip with high reliability can be obtained easily at low cost.

In all of the above-mentioned first to third embodiments, the holding angle of the printed wiring board is not specified, but the air is exhausted by the air exhausting means.
If it was kept at a general allowable angle, it was possible to secure a highly reliable encapsulation resin coating step having moisture resistance and other characteristics. However, although not shown, if the printed wiring board or the like is held horizontally in the first to third embodiments, it is expected that the bare chip sealing resin application step in the highly reliable F / C mounting method can be provided. It goes without saying that you can do it.

[0016]

As described above, according to the present invention,
The following effects are obtained. The sealing resin is forced to flow in and out by a small diameter through hole provided in the printed wiring board or by an air discharging means (vacuum device, air suction device and compressed air device) connected to the small diameter through hole. Therefore, the coating time of the sealing resin can be shortened, and it is not necessary to tilt the printed wiring board at the time of coating the sealing resin as in the conventional case. Not only can the sealing resin be densely filled, but also the air mixed in the sealing resin can be removed at the time of filling.

Further, it can be confirmed that the sealing resin is filled between the printed wiring board and the bare chip at the connection point between the small diameter through hole provided on the printed wiring board and the air discharge device.

Therefore, it is not necessary to incline the printed wiring board, the coating work of the sealing resin can be carried out quickly, and the bare chip in the highly reliable flip chip mounting method which is excellent in moisture resistance, durability and impact resistance. It is possible to provide a sealing resin applying step.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a bare chip according to a first embodiment of the present invention.

FIG. 2 is an external perspective view showing the printed wiring board according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a state in which a bare chip is mounted on the printed wiring board according to the first embodiment of the present invention.

FIG. 4 is a process diagram of applying a sealing resin to a bare chip according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing the end of the step of applying the sealing resin to the F / C-mounted bare chip of the first embodiment of the present invention.

FIG. 6 is a side sectional view of an essential part showing a second embodiment of the present invention.

FIG. 7 is a side sectional view of a main part showing a third embodiment of the present invention.

FIG. 8 is an external perspective view of a main part showing a conventional bare chip mounting step.

FIG. 9 is a perspective view of a main part appearance showing a conventional bare chip sealing resin application step.

FIG. 10 is a diagram showing the completion of application of a conventional bare chip sealing resin.

[Explanation of symbols]

 11,21,31 Bear chip 12,22,32 Printed wiring board 12a, 22a, 32a Small diameter through hole 13,23 FC mounting pad 14,24,34 Sealing resin 15,17,37 Dispenser 26 Air suction device

Claims (5)

[Claims] 1. A flip which is characterized in that, in a step of applying a sealing resin in a flip chip mounting method, a space between the flip chip mounting bare chip and a printed wiring board is evacuated by an air discharging means to perform resin sealing. Chip mounting bare resin chip coating process. 2. The step of applying a sealing resin to a flip chip mounting bare chip according to claim 1, wherein the air discharging means is a vacuum device provided in a working area for applying a sealing resin to the flip chip mounting bare chip. 3. The air suction device is an air suction device connected to a small-diameter through hole provided at a central portion of the printed wiring board facing the bottom surface of the bare chip of the printed wiring board.
Encapsulation resin application step for the flip chip mounting described. 4. The flip according to claim 1, wherein the air discharge means is a dispenser which is connected to a small-diameter through hole provided in a central portion of the printed wiring board facing the bottom surface of the bare chip and is driven by compressed air. Chip mounting bare resin chip coating process. 5. The step of applying a sealing resin to a flip chip mounting bare chip according to claim 1, wherein the printed wiring board is held horizontally.