JP2536425B2 - Method and apparatus for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a lead-on-chip (hereinafter referred to as LOC) structure in which a semiconductor element is bonded to a lead frame by a film and the inner lead of the semiconductor element is electrically connected to the semiconductor element. In particular, it relates to an apparatus and method for bonding a semiconductor element to a lead frame.

[0002]

2. Description of the Related Art In a conventional LOC structure semiconductor device, a semiconductor element 2 is bonded to an inner lead 1a of a lead frame 1 with an insulating film 3 as shown in FIG.
The electrode portion of the semiconductor element 2 and the inner lead 1a are electrically connected by a metal wire 5, sealed with a resin 6, and then the outer lead 1b of the lead frame 1 is cut and bent. Here, as the insulating film 3 for adhering the semiconductor element 2 to the lead frame 1, a polyimide film whose both surfaces are coated with a thermoplastic adhesive 4 is used.

FIG. 4 is a view for explaining a method of adhering the semiconductor element 2 to the lead frame 1 using this polyimide film 3. As shown in FIG. 5 (a), the polyimide film 3 coated with thermoplastic adhesives 4 on both sides is temporarily fixed to the lead frame 1, while the semiconductor element 2 is positioned on the heater block 31 and vacuum suction is performed. Fix it. Then, as shown in FIG. 5B, the lead frame 1 is brought into contact with the semiconductor element 2, and the pressing body 32 is lowered from the upper side thereof. The polyimide film 3 and the semiconductor element 2 are adhered while being pressed and heated.

By the way, in this type of semiconductor device, when air bubbles are present in the thermoplastic adhesive 4 of the polyimide film 3 for adhering the semiconductor element 2 to the lead frame 1,
Wire bonding may be adversely affected. That is, when bubbles are present in the adhesive 4 near the wire bonding portion of the inner lead 1a, ultrasonic waves applied to the wire bonding portion through the semiconductor element 2 are absorbed by the bubbles and are transmitted to the wire bonding portion of the inner lead 1a. This is because ultrasonic bonding cannot be performed. Further, when the air bubbles reduce the adhesiveness between the semiconductor element 2 and the lead frame 1 to cause partial peeling, the adhesiveness of the resin 6 in this portion is reduced, and the outer lead 1b is completed after the semiconductor device is completed. This also causes the reliability of the semiconductor device to be deteriorated, such as cracking of the resin 6 due to external force during soldering.

[0005]

Conventionally, pressure is applied by the pressure body 32 and heating by the heater block 31 to perform adhesion. However, the pressure body 32 uniformly applies a surface to the polyimide film 3. Adhesive 4 to apply pressure
The bubbles generated inside are simply crushed and cannot escape to the side, and it is difficult to enhance the effect of removing the bubbles. Further, when the bonding is performed at a high temperature, since the adhesive 4 is softened, the bubbles are easily moved in the adhesive, and even when the pressure is applied, the bubbles are caught in the adhesive 4 and are difficult to remove. . Therefore, it is easier to remove air bubbles by performing the bonding at a low temperature, but in order to perform the bonding with the above-mentioned thermoplastic adhesive 4, it is not possible to lower the temperature below a predetermined temperature, and the air bubbles are effectively removed. Is difficult.

As a technique for adhering a film of this type, Japanese Patent Laid-Open No. 20987/1990 proposes a method using a roller, and it is considered that this technique is effective for removing bubbles. However, this technique is effective when a material having a large heat capacity does not exist on the roller side, but when a semiconductor element having a large heat capacity and a lead frame exist on both sides like LOC, this technology is applied as it is. It's difficult. That is, when the roller side is a film having a small heat capacity as in this publication, it can be bonded by heating the aluminum substrate side having a large heat capacity with a heater, but like the LOC described above, the lead frame is attached to the roller side. Alternatively, when any of the semiconductor elements is present, for example, the temperature of the lead frame located on the roller side is hard to rise, and effective bonding becomes impossible.

Even if the roller is used in the high temperature condition required for bonding, the bubbles are apt to be caught in the adhesive in the high temperature condition as described above. Therefore, the bubbles should be pushed out to the side to be removed. Is difficult An object of the present invention is to provide a method and apparatus for manufacturing a semiconductor device in which bubbles in the adhesive are effectively removed and the reliability of adhesion between the lead frame and the semiconductor element is improved.

[0008]

According to the manufacturing method of the present invention, a step of heating the adhesive at a low temperature and pressing the lead frame and the semiconductor element while rolling the roller, and the step of increasing the lead frame and the semiconductor element are performed. Heating at a temperature and pressurizing both at a flat pressure. In this case, it is preferable that the roller rolls from the bonding portion of the inner lead of the lead frame toward other portions. In the semiconductor device manufacturing apparatus of the present invention, the first stage heats the adhesive for bonding the lead frame and the semiconductor element at a low temperature and presses the lead frame and the semiconductor element while rolling the rollers. And a second stage that heats the lead frame and the semiconductor element at a high temperature and pressurizes them to bond them. For example, the first stage is provided with a semiconductor block and a heater block that is heated to a low temperature, and is arranged to face the heater block.
The semiconductor device includes a roller that rolls on the surface of the lead frame or the semiconductor element and presses the semiconductor element and the lead frame between the heater block and the heater block, and the second stage is heated to a high temperature and the semiconductor element is heated. And a pair of heater blocks for planarly pressing the lead frame.

[0009]

Next, the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of the manufacturing apparatus of the present invention. In the figure, the lead frame 1 is formed in a long belt shape in which a plurality of units are integrally formed in series, and is configured to be intermittently moved from left to right in the figure by a drive mechanism (not shown). To be done. Further, the first stage 10 and the second stage 20 are arranged along the lead frame 1 at an interval corresponding to the unit interval of the lead frame 1. A heater block 11 is arranged on the lower side of the first stage 10, and a semiconductor element 2 to be bonded is positioned on the heater block 11 as will be described later and is supported by vacuum suction with its surface facing upward. It Further, a roller 12 is arranged immediately above it and rotated by a drive mechanism (not shown). The heater block 11 and the roller 12 are configured to be moved in the vertical direction, and the lead frame 1 is pressed by the roller 12 and the heater block 11 in the vertical direction. The rotation speed and the rotation direction of the roller 12 can be arbitrarily controlled.

A heater block 21 is arranged on the lower side of the second stage 20, and a heater block 22 also serving as a pressing body is arranged on the upper side. These heater blocks 21 and 22 are also configured to be vertically movable.
In addition, the temperature of each heater block of the first stage 10 and the second stage 20 is configured to be specially controllable, and the temperature in the first stage 10 is set to the second stage 2.
It is set lower than the temperature at 0.

The manufacturing method of the present invention in this configuration will be described. First, as shown in FIG. 2A, a polyimide film 3 coated with thermoplastic adhesives 4 and 4 on both sides is temporarily fixed to the lower surface of the inner lead 1a of each unit of the lead frame 1. On the other hand, the semiconductor element 2 is supplied to the heater block 11 of the first stage 10 and supported at a predetermined position. Then, when the unit of the lead frame 1 is moved to a predetermined position and the polyimide film 3 temporarily fixed to the lead frame 1 reaches a position directly above the heater block 11, as shown in FIG. 11 is moved up. At the same time, the roller 12 is moved downward to press the semiconductor element 2 and the lead frame 1 from above and below. Then, the roller 12 is rotated while the semiconductor element is heated at a relatively low temperature by the heater block 11,
Roll over the lead frame 1 from left to right. As a result, the adhesive 4 is slightly softened to bond the semiconductor element 2 to the lead frame 1, and the bubbles existing in the adhesive 4 are pushed out to the side. After that, the heater block 11 moves down, and the roller 12 moves up and is retracted.

Then, as shown in FIG. 2C, the lead frame 1 is moved rightward by one unit, and the semiconductor element 4 is moved to the second position.
When positioned on the heater block 21 of the stage 20,
The heater blocks 21 and 22 are respectively moved up and down to pressurize the semiconductor element 2 and the lead frame 1 in a planar state, and simultaneously heat them at a high temperature. As a result, the adhesive 4 is also heated to a high temperature and sufficiently softened, and the lead frame 1
And the semiconductor element 2 are completely bonded.

Here, the temperature of the heater blotter 11 in the first stage 10 is the glass transition point of the adhesive 4 + about 40 ° C. or more, and the semiconductor element 2 and the film 3 can be temporarily fixed, and this temperature is relatively high. Since the adhesive 4 is not so softened because of the low temperature, therefore, even if the roller 12 rolls, it is possible to prevent the entrainment of bubbles as when the adhesive 4 is softened and push the bubbles to the side. Can be effectively removed. Moreover, since the temperature of the heater blocks 21 and 22 in the second stage 20 is equal to or higher than the glass transition point of the adhesive 4 + about 100 ° C., the adhesive 4 is sufficiently softened and a short time of 1 to 2 seconds is sufficient. It becomes possible to obtain adhesion. At this time, when pressing the flat surfaces by both the heater blocks 21 and 22, it is not necessary to perform parallel alignment so strictly, and the adjustment time can be shortened.

Therefore, according to this method, the roller 1 is held in the first stage 10 while the adhesive 4 is kept at a low temperature.
The bubbles existing in the adhesive 4 can be surely removed by rolling the roller 2. After that, by heating at a high temperature in the second stage 20, the semiconductor element 2 is bonded by the adhesive 4.
It is possible to quickly bond the semiconductor chips, and it is possible to realize highly reliable bonding of the semiconductor element. It should be noted that FIG.
As shown in the drawing corresponding to the step of (1), when the roller 12 is pressed and rolled, the roller 12 is directed toward both sides from the central portion of the semiconductor element 2, that is, at the tip of the inner lead 1a of the lead frame 1. By rolling the bonding portion from the bonding portion toward the outer lead 1b in two times in each direction, it is possible to more effectively remove the bubbles immediately below the bonding portion.

[0015]

As described above, according to the manufacturing method of the present invention, the adhesive is heated at a low temperature and the lead frame and the semiconductor element are pressed while rolling the roller, and then the lead frame and the semiconductor element are pressed. Since they are heated at a high temperature and both of them are flatly pressed, air bubbles existing in the adhesive can be reliably removed by rolling the roller while keeping the adhesive at a low temperature. Further, by subsequently heating at a high temperature, it becomes possible to quickly bond the semiconductor element with the adhesive, so that highly reliable bonding of the semiconductor element can be realized. Further, by rolling the roller from the bonding portion of the inner lead toward the other portion, it becomes possible to reliably remove the bubbles from the bonding portion. The manufacturing apparatus of the present invention has a first stage and a second stage. The first stage heats the adhesive at a low temperature, and presses the lead frame and the semiconductor element while rolling the rollers. Since the second stage is configured to heat the lead frame and the semiconductor element at a high temperature and pressurize them to adhere to each other, removal of bubbles by the method of the present invention and the lead frame and the semiconductor element are performed. Can be effectively adhered to. Therefore, stable bonding of the semiconductor element and the lead frame can be obtained, suitable wire bonding can be realized, and cracking of the resin mold can be avoided even during solder mounting of the semiconductor device.

[Brief description of drawings]

FIG. 1 is a front configuration diagram of an embodiment of a manufacturing apparatus of the present invention.

FIG. 2 is a front view showing the manufacturing method of the present invention in the order of steps.

FIG. 3 is a front view showing a part of the process of another embodiment of the present invention.

FIG. 4 is a sectional view of an example of an LOC to which the present invention is applied.

FIG. 5 is a front view showing a conventional manufacturing method in process order.

[Explanation of symbols]

 1 Lead Frame 2 Semiconductor Element 3 Polyimide 4 Adhesive 10 First Stage 11 Heater Block 12 Roller 21 Heater Block 22 Heater Block

Claims (4)

(57) [Claims] 1. A method of manufacturing a semiconductor device in which a semiconductor element is adhered to a lead frame with an adhesive that produces an adhesive force by heating, wherein the adhesive is heated at a low temperature,
And a step of heating the lead frame and the semiconductor element while rolling the roller, and a step of heating the lead frame and the semiconductor element at a high temperature and pressurizing them both on a plane. Method. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the roller is rolled from the bonding portion of the inner lead of the lead frame toward another portion. 3. An apparatus for manufacturing a semiconductor device in which a semiconductor element is bonded to a lead frame with an adhesive that produces an adhesive force by heating, wherein the adhesive is heated at a low temperature,
And a first stage for pressing the lead frame and the semiconductor element while rolling the roller, and a second stage for heating the lead frame and the semiconductor element at a high temperature and pressing and bonding them. And a semiconductor device manufacturing apparatus. 4. The first stage has a heater block on which a semiconductor element is mounted and is heated to a low temperature, and the heater block is arranged to face the heater block and rolls on the surface of the lead frame or the semiconductor element to roll the heater block. 4. A roller that presses the semiconductor element and the lead frame between the second stage and the second stage, and the second stage includes a pair of heater blocks that are heated to a high temperature to planarly press the semiconductor element and the lead frame. Semiconductor device manufacturing equipment.