JPH04338513A - Sensing method for mold clamping force for mold clamping device - Google Patents

Abstract

PURPOSE:To monitor continuously molding clamping force set initially, improve yield of quality following the stabilization of mold clamping force and adjust the unevenness of a top force and a bottom force easily. CONSTITUTION:Four pieces of blocks 2 are mounted on the four corners of the mold end face of a top force 1. Four pieces of piezoelectric elements 4 are embedded in the corners of the upper end face of a bottom force 3 correspondingly to said blocks 2. Voltage indicators 5 are connected with said respective piezoelectric elements 4. At the time of mold clamping, the piezoelectric elements 4 are pressed by the blocks 2, and the distortion amount of the piezoelectric elements 4 generated by pressing is sensed as the potential difference and the conversion to the mold clamping force is carried out.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting mold clamping force in a mold clamping device used for resin encapsulation of semiconductor elements.

0002

2. Description of the Related Art A conventional detection method of this type will be explained with reference to FIG. Reference numeral 1 denotes an upper mold fixed to the main body of the apparatus, 3 a lower mold that moves up and down by a drive means (not shown), and 6 a tie bar that indirectly supports the upper mold 1 and the lower mold 3. A strain gauge 7 is bonded to the tie bar 6 along its longitudinal direction, and the amount of strain in the strain gauge 7 is detected by a voltmeter 5.

The operation will be explained below. The lower mold 3 is pushed up by a drive system (not shown) and brought into contact with the upper mold 1, thereby performing necessary mold clamping. At this time, the tie bars 6 elongate along the longitudinal direction as the mold is clamped, and the amount of elongation is detected by the strain gauge 7 and converted into voltage by the voltmeter 5, whereby a predetermined mold clamping force is obtained. Check that the

0004

[Problem to be Solved by the Invention] In the conventional detection method described above, the initial strain amount of the strain gauge under no load changes as the mold clamping is repeated several times. A difference arises between the initial mold clamping force (strain amount) and the initial strain amount, and a problem arises in that it is impossible to confirm whether a predetermined mold clamping force is obtained using the strain value obtained by the strain gauge. At the same time, there is an inconvenience that skill is required to adjust the contact between the upper mold and the lower mold. The present invention has been made in view of the above-mentioned conventional disadvantages, and its purpose is to enable continuous monitoring of the initially set mold clamping force and to improve quality yield by stabilizing the mold clamping force. It is an object of the present invention to provide a method for detecting mold clamping force in a mold clamping device, which enables the detection of mold clamping force in a mold clamping device.

[0005]

[Means for Solving the Problems] In order to achieve this object, a method for detecting mold clamping force in a mold clamping device according to the present invention fixes a plurality of blocks to the lower end surface of an upper mold, and A piezoelectric element is embedded in the upper end surface of the lower mold corresponding to the block, and the distortion of the piezoelectric element caused by the block pressing the piezoelectric element when clamping the upper mold and the lower mold is suppressed. The mold clamping force is detected by converting it into voltage.

[0006]

[Operation] In the present invention, the mold clamping force is detected by converting the strain of the piezoelectric element into voltage. Furthermore, by comparing the voltages of piezoelectric elements provided at multiple locations, it is possible to grasp the clamping state of the upper mold and the lower mold.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, four blocks 2 are attached to the four corners of the lower end surface of the upper mold 1. Four piezoelectric elements 4 are installed at the four corners of the upper end surface of the lower mold 3 corresponding to these blocks 2.
is buried. Each of these four piezoelectric elements 4 is connected to a voltmeter 5 for detecting distortion of these piezoelectric elements.

The operation will be explained below. In order to perform mold clamping, a drive source (not shown) pushes the lower mold 3 upward and presses it against the upper mold 1 to perform mold clamping. At this time, the block 2 of the upper mold 1 pushes the piezoelectric element 4 of the lower mold 3, the amount of distortion of the piezoelectric element 4 caused by this pushing amount is detected by the voltmeter 5, and the voltage is converted into mold clamping force. do. At this time, the voltage values of each voltmeter 5 are compared at the same time to determine the mold clamping state.

[0009]

[Effects of the Invention] As explained above, according to the present invention,
The mold clamping force is detected using a block attached to the upper mold and a piezoelectric element embedded in the lower mold, so that the amount of strain in the piezoelectric element can be converted into voltage and the clamping force can be converted to a voltage, so the piezoelectric element is always stable. The amount of strain can be obtained, and the mold clamping force can be continuously and accurately determined, so that a stable mold clamping force can be continuously obtained without change. Further, by understanding the voltages from the piezoelectric elements at a plurality of locations, there is an effect that adjustment of the mold contact between the upper mold and the lower mold is facilitated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a method for detecting mold clamping force in a mold clamping device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a method for detecting mold clamping force in a conventional mold clamping device.

[Explanation of symbols]

1 Upper mold 2 Block 3 Lower mold 4 Piezoelectric element 5 Voltmeter

Claims (1)

[Claims] 1. In a mold clamping device having an upper mold and a lower mold, a plurality of blocks are fixed to the lower end surface of the upper mold, and a plurality of blocks are fixed to the upper end surface of the lower mold corresponding to the blocks. A piezoelectric element is embedded, and when the upper mold and the lower mold are clamped, the block presses the piezoelectric element and the strain of the piezoelectric element is converted into voltage to detect mold clamping force. A method for detecting mold clamping force in a mold clamping device.