JPS6278838A - Resin sealing device for semiconductor element - Google Patents

Abstract

PURPOSE:To control the plunger speed arbitrarily with high precision while facilitating its maintenance by a method wherein the speed of motor-driven plunger is controlled by a a microcomputer correspondingly to the position of a movable platten etc. CONSTITUTION:When an upper metallic mold 5 mounted on an upper platten and a lower metallic mold 6 mounted on a movable platten 4 come into contact with each other at specified clamping pressure, they are mold clamped. After finishing mold clamping, a plunger 9 driving AC servomotor 10 starts turning to lift the plunger 9. Then a microcomputer 13 detects that the plunger 9 started lifting to control the moving speed of plunger 9 in three steps until resin feeding is finished. As soon as the resin feeding is finished, pressurizing time counting is started and simultaneously the motor speed is decelerated down to ultra low speed to keep the feeding pressure and as soon as the pressurizing time up is detected in said low speed, the motor 10 is released from the current-limit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin sealing device for semiconductor elements for resin sealing semiconductor elements on lead frames.

[Conventional technology]

In general, a resin sealing device for semiconductor devices includes an upper platen 1. As shown in FIG. A lower platen 2, a tie bar 3 provided between these two platens, and a movable platen 4 movably provided along the tie bar 3. The upper mold 5 is installed on the upper platen 1, the lower mold 6 is installed on the movable platen 4, and the movable platen 4 is driven by hydraulic pressure to separate the upper mold 5 and the lower mold 6. The molds are clamped, and the lead frame and semiconductor element placed between the two molds are sealed with resin.

The structure of a conventional plunger portion in such a device is shown in FIG. In the figure, 7 is a tablet insertion hole into which a sealing resin (tablet) 8 is inserted, and 9 is the insertion hole 7.
This plunger is slidably arranged as a cylinder, and is driven by a hydraulic plunger drive unit (not shown) to inject the resin 8 into the mold.

[Problem that the invention seeks to solve]

However, in such a conventional device, the plunger 9
Since the plunger 9 is driven by hydraulic pressure, it is not possible to adjust the speed etc. of the plunger 9. For example, when ejecting a semiconductor element that has been sealed with resin, depending on the moving speed of the plunger 9, the hardened resin (hereinafter referred to as There was a problem that cracks occurred in the (denoted as "Cull").

This will be explained in detail below using the schematic diagram of FIG. When the resin sealing is completed, the mold is opened and the movable platen 4 is lowered in the direction shown in the figure. When the movable platen 4 is lowered to a predetermined position, the eject pin 19 provided on the lower platen 2 comes into contact with the lead frame 20 in the mold, as shown in FIG. Simultaneously with this contact, the plunger 9 is raised to eject the cull, and the rising speed of the plunger 9 and the descending speed of the movable platen 4, that is, the ejecting speed of the cull and the lifting speed of the lead frame by the eject pin. If the values are different, the cull may be tilted and subjected to excessive force during ejection, and the cull may break.

Therefore, in order to prevent this cracking, it is considered that the rising speed of the plunger 9 should be set to the same speed as the descending speed of the movable platen 4, but as mentioned above, in the conventional hydraulic drive system, the driving hydraulic pressure of the plunger 9 is used to apply the force. It only controlled the pressure, not the speed.

The present invention has been made in view of these points, and an object of the present invention is to obtain a resin sealing device for a semiconductor element that can easily and precisely control the speed of the plunger.

[Means for solving problems]

The resin sealing device for semiconductor elements according to the present invention is provided with a plunger speed control means for driving the plunger for injecting and pressing resin with a motor and controlling the speed of the plunger, so that when ejecting, the moving speed of the plunger is controlled by the moving platen. The speed is set to be the same as the descending speed of .

[Effect]

In this invention, the plunger is driven by a plunger motor such as an AC servo motor, and the moving speed of the plunger is controlled by adjusting the frequency of pulses supplied to the motor. This makes the ejection speed of the cull the same as the speed of raising the lead frame by the eject pin, thereby preventing cracking of the cull.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Here, in the following explanation, a case of a single plunger will be explained as an example. FIG. 1 is a diagram showing a functional block diagram of a plunger driving section in a resin sealing device for a semiconductor element according to an embodiment of the present invention.

This embodiment is provided with a plunger motor 10 that provides a driving force for driving the plunger 9, and an eject start detection means 11 that detects the ejection start time based on the position of the moving platen 4.
The moving speed of the plunger 9, that is, the ejecting speed of the plunger 9 at the time of ejection is controlled by the plunger speed control means 12 which receives the detection signal of the moving platen 4, so that it becomes the same as the descending speed of the movable platen 4.

FIG. 2 shows an overall configuration diagram of a resin sealing device for semiconductor elements in which the plunger drive section described above is used. In this embodiment, the movable platen 4 is also driven by the platen driving motor 51, and is completely electric. That is, the movable platen 4 is moved by converting the rotation of the motor 51 into thrust by a driving force conversion mechanism (not shown). Further, the plunger is provided in the lower mold 6, and the movable platen 4
It is designed to be driven via a plunger motor lO and a gear 1-rain 52, etc., which are attached to the.

FIG. 3 shows an example of a specific configuration for realizing the functional blocks of the plunger drive section shown in FIG.
10 is an AC servo motor as a plunger motor, 1
7.18 are respectively moving platens 4. This is a potentiometer for detecting the position of the plunger 9. Also 13
is a microcomputer, which uses the output signals of the potentiometers 17 and 18 as input, exchanges signals with external devices 15 such as the moving platen drive motor 51, and controls the rotational speed of the AC servo motor 10. This is for controlling, limiting current (torque), etc. Reference numeral 14 denotes a servo amplifier that receives commands from the microcomputer 13 and controls the drive of the AC servo motor 10. The microcomputer 13 and potentiometer 17 cause the ejection start detection means 11 shown in FIG. Further, a plunger speed control means 12 is constituted by a microcomputer 13 and a servo amplifier 14.

Further, 16 is a plunger drive mechanism for converting the rotational force of the AC servo motor 10 into a thrust force for moving the plunger 9, and this is attached to the output shaft of the AC servo motor 10 as shown in FIG. Plunger drive shaft 16a and plunger 9 connected via gear train 52 etc.
It consists of a nut 16b fixed to, a ball screw 16c engaged with the nut 16b, and a pair of bevel gears 16d and 16e provided at one end of the plunger drive shaft 16a and ball screw 16c, respectively.

Next, the operation will be explained.

First, the operation before the plunger operates, that is, until the mold is clamped, will be explained. When the start switch is turned on,
The platen drive motor 51 starts rotating, and the rotation is converted into thrust via a drive force conversion mechanism (not shown), thereby causing the movable platen 4 to rise. Then, when the upper mold 5 and the lower mold 6 come into contact and a certain tightening pressure is reached, the motor 51 is servo-locked and the molds are clamped.

Resin sealing is performed in this mold-clamped state, and the operation of the plunger in this case will be explained with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing a plunger operation control program stored in the memory of the microcomputer 13, and FIG. 5 is a diagram showing its driving pattern.

First, when the mold clamping is completed, the AC servo motor 10 for driving the plunger 9 starts rotating, and this rotational force is transmitted to the ball screw 16C via the bevel gear pair 16d, 16e. As the ball screw 16c rotates, the nut 16b, that is, the plunger 9, which is engaged with the ball screw 16c rises. Then, the microcomputer 13 activates the plunger 9
It is detected in step 20 that the resin has started to rise, and then in steps 21 to 26, the speed of the motor 10 is controlled to control the moving speed of the plunger 9 in three stages until the resin injection is completed. That is, position p.

When it is detected that the resin injection pressure has risen to the position P1, the current to the motor 10 is limited (torque limited) in order to make the resin injection pressure a desired pressure. At the same time, the motor speed is reduced to v2 and resin is slowly injected.

The resin is injected in this way, and when it is detected by the output of the potentiometer 18 that the positional fluctuation of the plunger 9 has become less than the specified value, that is, the resin injection is completed (step 27), the pressure is increased from this point onwards. Time counting is started (step 28). At the same time,
In order to maintain the injection pressure, the motor speed is reduced to a very low speed (3), and when the pressurization time amplifier is detected in this state, the motor current limit is turned off (steps 29 to 31). Note that at the time of the motor speed v3, the plunger 9 is actually stopped.

Next, in steps 32 to 35, the plunger 9 is lowered by P2 at motor speed V4 and raised at V5, and the plunger 9 and the resin are separated. Further, in steps 36 to 41, the lead frame and the semiconductor element that have been sealed with resin are taken out, that is, ejected.

Here, the operation at the time of ejection will be explained in more detail. When the above peeling process is completed, a mold opening signal is output to the movable platen driving motor 51, which is an external device (step 36), and the movable platen 4 is lowered. When the movable platen 4 descends a predetermined distance, the lead frame comes into contact with the eject pin provided on the lower platen 2, as shown in FIG. 8 described above. The absolute position of the moving platen 4 at this time is stored in advance in the microcomputer 13,
The microcomputer 13 receives the detection output of the potentiometer 17, which is the position of the moving platen 4, and detects the point of contact between the lead frame and the eject, that is, the start of the ejecting process (step 37). And from this point on,
The plunger 9 starts to move upward, and at this time the motor speed is controlled to 6 so that the speed of the plunger 9 becomes the same as the downward speed of the movable platen 4. After the plunger 9 rises by P3 from the position at the start of ejection (step 39), it outputs a signal to the outloader, which is an external device (step 40), so that the semiconductor element, which has been completely sealed with resin, is removed to the outside. Served.

Next, the mold surface is cleaned in steps 41 to 48, and the plunger 9 is cleaned in steps 49 and 50.
returns to the origin of the main drive pattern. During this time, the plunger 9 is controlled to once rise by P4 at motor speed V7, then fall to position P5, and after completion of cleaning, further descend to the origin at motor speed 9.

In the device of this embodiment, the plunger 9 is driven and controlled by the AC servo motor 10 and the microcomputer 13, so there is no oil leakage, and a clean device that is easy to maintain and inspect can be realized. Furthermore, the speed of the plunger can be controlled easily and with high precision, which was impossible with conventional hydraulic drive systems. In particular, in this embodiment, the speed of the plunger 9 is controlled to make the ejection speed of the cull the same as the descending speed of the movable platen 9 during ejection, thereby preventing the cull from being tilted and cracking during ejection. can do.

In the above embodiment, the ejection is detected by the microcomputer that receives the output from the potentiometer 17, but in this case, a separate control system is provided, the control system detects the start point of ejection, and the detection output is The information may be input to a microcomputer, and the same effect as in the above embodiment can be achieved.

Furthermore, the position detectors for the movable platen and plunger are not limited to potentiometers as in the above embodiments, and of course, for example, absolute type encoders may be used.

〔Effect of the invention〕

As described above, according to the resin sealing device for semiconductor elements according to the present invention, 1. The plunger is driven by a motor, and
The speed of the plunger is controlled by a microcomputer according to the position of the movable platen, etc., making maintenance easier and allowing high-quality resin sealing by controlling the speed of the plunger arbitrarily and with very high precision. This is especially effective in preventing cracking of the cull during ejection.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of a plunger drive section of a resin sealing device for semiconductor devices according to an embodiment of the present invention, FIG. 2 is an overall configuration diagram of the device, and FIG. 3 is a function diagram of the functions shown in FIG. 1 above. FIG. 4 is a flowchart showing the operation of the plunger of the device, FIG. 5 is a diagram showing the driving mechanism of the plunger of the device, and FIG. FIG. 7 is an enlarged view showing the plunger portion of the conventional resin sealing device for semiconductor elements, and FIG. 8 is a diagram for explaining the operation at the time of ejection. 5... Upper mold, 6... Lower mold, 9... Plunger, 10... AC servo motor, 11... Eject start detection means, 12... Plunger speed control means, 1
3... Microcomputer, 14... Servo amplifier, 17.18... Potentiometer. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 2 Figure 3 Figure 1c; Figure 6 Figure 8 F

Claims (1)

[Claims] (1) It has an upper platen, a lower platen, and a movable platen movably provided between them, and inside both the upper mold and the lower mold installed on the upper platen and the movable platen, respectively. A resin sealing device for a semiconductor element that accommodates a lead frame and a semiconductor element and seals them with resin includes a plunger provided in the lower mold for injecting and pressing the resin, and a drive for driving the plunger. a plunger motor that applies force; and a plunger motor that detects the position of the movable platen when the movable platen is lowered after resin sealing is completed, and detects the start point of a process for ejecting the resin-sealed semiconductor element from the mold. A resin sealing apparatus for a semiconductor element, comprising: eject start detection means for detecting ejection start; and plunger speed control means for raising the plunger at the same speed as the lowering speed of the movable platen in response to the detection result.