JP2679224B2 - Method for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To prevent air bubbles from being confined in sealing resin, and increase reliability by a method wherein, after die bonding adhesive agent is arranged so as to occupy an area larger than an IC on a wiring substrate, and the outer periphery of the IC is buried in the die bonding agent to be bonded and fixed, the IC is sealed by printing system with sealing resin. CONSTITUTION:By printing system, die bonding adhesive agent is supplied to a part of a wiring substrate 12, so as to occupy an area larger than a semiconductor integrated circuit 14, and the periphery thereof is buried in the die bonding adhesive agent 13 to be fixed. Then the semiconductor integrated circuit 14 on the wiring substrate 12 is sealed by printing system with sealing resin 17. For example, by printing system, the die bonding adhesive agent 13 like insulative epoxy resin is supplied to a part of the wiring substrate 12 on which conductor wiring 11 is arranged; the IC 14 is arranged at the almost central part and mounted by applying a specified load. After the aluminum pad of the IC 14 and conductor wiring 11 are connected by conductor wires 16 such as gold and aluminum, the following are sealed by printing system with the sealing resin 17; the conductor wiring 11, the die bonding adhesive agent 13, the IC 14, and a part of the conductor wires 16.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called COB (Chip On Board) method for directly mounting a semiconductor integrated circuit (hereinafter referred to as an IC) on a wiring board.

Conventional technology A COB method that directly mounts a bare chip aiming at high density and cost reduction, instead of the surface mounting method that mounts a conventional semiconductor package on a wiring board (eg epoxy board, ceramic board, glass board, etc.) Has entered the stage of mass production. This manufacturing process is as shown in FIG.
For example, an epoxy-based die bond adhesive 3 is supplied to a predetermined position of the wiring board 2 on which the conductor wiring 1 is applied by a dispenser, a transfer method or the like (Fig. 2a), and the IC 4 is mounted in accordance with the die bond adhesive 3 described above. Place and bond and fix (second
Figure b). Then, the pad (not shown) of the IC4 and the conductor wiring 1 are connected by a conductor wire 5 of gold, aluminum or the like (Fig. 2c), and further, the IC4 and the conductor wire 5 are potted, printed, etc. Is used to seal with an epoxy-based sealing resin 6 (FIG. 2d). Conductor wiring 1 for high-density mounting
Since it is wired up to the vicinity of the IC4, it does not come into contact with the conductor wiring 1, so the amount of the die bond adhesive 3 supplied is small, and even if the IC4 is adhered and fixed, the die bond adhesive 3 is entirely on the end surface of the IC4. There is nothing to see. That is, a cavity is formed in a part of the back surface of the IC4. When the sealing resin 6 is supplied by the potting and printing method, which is the normal pressure filling that complies with the COB method on the large-sized substrate with the cavity on the back surface of the IC4, the sealing resin 6 is supplied at the normal pressure. Therefore, the air bubbles 7 remain without being filled in the cavity formed in a part of the back surface of the IC4.
Further, since the thickness of the above IC4 is usually as thick as about 400 μm, when the sealing resin 6 is rapidly supplied from above the IC4 under normal pressure, the sealing resin 6 is not completely supplied in the vicinity of the IC4. Similarly, the bubbles 7 remain.

Problems to be Solved by the Invention In the case of a general IC package, even if there is a cavity without a die bond adhesive on the back surface of the IC mounted and fixed on the lead frame, the sealing method is several tens kg / cm ² Since it is a transfer molding method in which the sealing resin is filled with the pressure of, the cavity is filled with the sealing resin, and even if the thickness of the IC is large, the filling pressure is also high, so that air bubbles do not remain in the sealing resin. rare. However, as described above, if the filling of the sealing resin 6 is a method of normal pressure such as potting and printing, the probability that the bubbles 7 remain in the sealing resin 6 is high.
A state of the reliability test of the IC 4 with the air bubbles 7 remaining in the sealing resin 6, for example, the presser cooker test in which the wiring board 2 is left at 121 ° C. and 2 atmospheric pressure will be described with reference to FIG. . The bubbles 7 in the encapsulation resin 6 also have a pressure of 2 atm, and when the wiring board 2 is exposed to the atmosphere, the bubbles 7 containing the gas at 2 atms expand rapidly and the IC 4 is extremely raised to the above-mentioned encapsulation. A state occurs in which the stop resin 6 is destroyed and the conductor wire 5 is broken. In order to solve such a problem, the supply area of the die bond adhesive 3 is expanded to
In the dispenser method, a multi-nozzle with a thin tip is used as a method for preventing the formation of cavities on the back surface of the nozzle. However, in the multi-nozzle, it was very difficult to control the amount of each nozzle and the reproducibility of the supply amount was a problem. . On the other hand, in the transfer method, the amount of the adhesive pulled up by the transfer jig varies widely and the thickness also varies greatly.
Further, in the supply of the sealing resin, the probability of incorporating air bubbles was low if the supply speed was extremely reduced in both the potting method and the printing method, but the mass productivity was poor.

Means for solving the problems And technical means of the present invention for solving the above problems,
Provide a die bond adhesive on the wiring board so that it has a larger area than the IC, embed the outer periphery of the IC in this die bond adhesive and fix it, and then seal the IC with a sealing resin by a printing method. It is a thing.

Action By covering the outer periphery of the IC with the die-bonding adhesive in this way, a steep step on the end face of the IC is mitigated, and when the sealing resin is applied onto the IC by printing, air bubbles may be trapped. Since it does not exist, it is possible to increase the manufacturing yield and improve the reliability.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a manufacturing process flow of a COB method according to an embodiment of the present invention. Wiring board 12 with conductor wiring 11
Die bond adhesive of insulating epoxy resin
13 is supplied by a printing method (Fig. 1a). In this case, the printing area of the die bond adhesive 13 is larger than the area of the IC 14 to be placed. For example, if the IC 14 is 5 × 5 mm, the printing area is 5.5 × 5.5 mm. This is because a part of the four end faces of the IC 14 is covered with the die bond adhesive 13. By the way, in the printing method of this embodiment, a 200-mesh stainless screen plate was used, and the thickness of the die bond adhesive 13 was 35 μm. Further, in the printing method, since it is relatively easy to control the printing area and the thickness of the die bond adhesive 13, it is possible to print up to the vicinity of the conductor wiring 11. Next, 5x5x0 on the center of the die bond adhesive 13.
Place the IC14 of 4 mmt and mount it with a predetermined load (Fig. 1b). This load causes the die bond adhesive 13
Partially bulges and covers a part of the outer peripheral portion 15 of the IC 14. Since the printed shape of the die bond adhesive 13 is similar to the IC 14 and is large, the outer peripheral surfaces 15 on the four sides of the IC 14 are covered with the die bond adhesive 13 almost evenly. Therefore, the steep step on the outer peripheral surface 15 of the IC 14 is relaxed by forming a taper with the die bond adhesive 13. By the way, the protrusion of the die bond adhesive 13 on the outer peripheral surface 15 was about 0.2 mm from the bottom of the IC 14. Further, since the die bond adhesive 13 is printed with a uniform thickness, no cavity is formed between the wiring board 12 and the back surface of the IC 14. Subsequently, the aluminum pad (not shown) of the IC 14 and the conductor wiring 11 are connected by a conductor wire 16 of gold, aluminum or the like (FIG. 1c). Finally, the conductor wiring 11, the die bond adhesive 13, the IC 14, and part of the conductor wire 16 are sealed with a sealing resin 17 (FIG. 1d). In this case, the method of supplying the sealing resin 17 uses a printing screen 18 having a predetermined pattern, a printing plate 18 made of metal or the like, and the sealing resin 17 is applied by printing with a squeegee made of urethane, for example. When printed, the thickness of the sealing resin 17 can be arbitrarily set by the distance A between the printing plate 18 and the wiring board 11, the thickness of the printing plate 18, and the like. By the way, in this embodiment, the printing plate 18 has a thickness of 0.
When a metal mask of 2 mm was used and the interval A was set to 0.5 mm, the thickness of the sealing resin 17 was 0.6 mm. In this embodiment, an insulating epoxy resin is used for the die bond adhesive 13, but any adhesive may be used as long as it is electrically conductive and printing is possible by a printing method. Further, the printing area of the die bond adhesive 13 is set to the IC14
Although it is larger, if the IC 14 is mounted and the outer peripheral surface 15 is evenly covered, the die bond adhesive 13
The printed area may be smaller than the IC14 by increasing the thickness of the IC14.

EFFECT OF THE INVENTION By supplying the die bond adhesive by the printing method of the present invention, no space is created between the wiring board and the IC, and the IC
Part of the outer peripheral surface of the IC is covered with a die-bonding adhesive to a uniform height, and the steps of the IC are alleviated if the steps of the IC are alleviated by encapsulating with an encapsulating resin in the same printing method. Air bubbles are not generated in the sealing resin, and the reliability of the semiconductor device can be improved. Further, since the printing method is used as the sealing method, it is possible to improve mass productivity.

[Brief description of the drawings]

1 (a) to 1 (d) are sectional views showing a manufacturing flow of the present invention, FIGS. 2 (a) to 2 (d) are sectional views showing a conventional manufacturing flow, and FIG. 3 is a conventional reliability test. It is sectional drawing which shows the destruction state of IC of a construction method. 13 ... die bond adhesive, 14 ... IC, 15 ... end face, 17 ...
… Encapsulating resin, 18 …… Printing plate.

Claims (1)

(57) [Claims] 1. A step of supplying a die bond adhesive to a part of a wiring board so as to have a larger area than a semiconductor integrated circuit by a printing method, and embedding an outer peripheral portion of the semiconductor integrated circuit on the die bond adhesive. A method of manufacturing a semiconductor device, comprising a step of fixing and a step of sealing the semiconductor integrated circuit on a wiring board with a sealing resin by a printing method.