Transfer molding apparatus and process

Claim 2

A transfer molding apparatus for sealing an electronic device in a resin by driving a plunger (5) downward in a pot (2) to inject the resin (11) into a mold (1), comprising: an electric motor (3) for driving the plunger; a motion converting mechanism (4) for converting the rotary motion of the output shaft of the electric motor into a linear motion; and displacement detector (10) for detecting the displacement of the plunger.

Claim 3

A transfer molding apparatus for sealing an electronic device in a resin (11) by driving a plunger downward in a pot (2) to inject the resin (11) into a mold (1), comprising: driving means (3, 4) consisting of an electric motor (3) for driving the plunger (5), and a motion converting mechanism (4) for converting the rotary motion of the output shaft of the electric motor into a linear motion; displacement detecting means (10) for detecting the displacement of the plunger; and control means (7,9:12) for controlling the pressure acting on the plunger so that a comparatively high pressure is applied to the plunger until the displacement of the plunger increases to a predetermined displacement, and a comparatively lower pressure is applied to the plunger after the displacement of the plunger has reached the predetermined displacement.

Claim 4

A transfer molding apparatus for sealing an electronic device in a resin (11) by driving a plunger downward in a pot (2) to inject the resin (11) into a mold (1), comprising: driving means (3, 4) consisting of an electric motor (3) for driving the plunger (5), and a motion converting mechanism (4) for converting the rotary motion of the output shaft of the electric motor into a linear motion; displacement detecting means (10) for detecting the displacement of the plunger; and control means (7,9:12) for controlling the pressure acting on the plunger so that a comparatively high pressure is applied to the plunger until the displacement of the plunger increases to a predetermined displacement, and a comparatively lower pressure is applied to the plunger after the displacement of the plunger has reached the predetermined displacement.

Claim 5

A transfer molding apparatus according to Claim 2, wherein a primary maximum current (i max1 ) and a secondary maximum current (imax2) are predetermined as upper limits of current to be supplied to the electric motor (3), the maximum current to be supplied to the electric motor is limited to the primary maximum current (i max1 ) until the displacement of the plunger (5) increases to the predetermined displacement, and the maximum current to be supplied to the electric motor (3) is limited to the secondary maximum current (i max2 ) after the displacement of the plunger (5) has increased to the predetermined displacement.

Claim 6

A transfer molding apparatus according to Claim 3, wherein the primary maximum current (i max ,), the secondary maximum current (i max2 ) and the predetermined displacement are set beforehand in a microcomputer (7) for controlling the movement of the plunger (5).

Claim 7

A transfer molding apparatus according to Claim 2, wherein the displacement of the plunger

Claim 8

(5) is detected on the basis of information provided by a pulse generator (10) associated with the electric motor.

Claim 9

(5) is detected on the basis of information provided by a pulse generator (10) associated with the electric motor.

Claim 10

A transfer molding apparatus according to Claim 2, wherein the motion converting mechanism comprises a ball screw jack.

Claim 11

A transfer molding apparatus for injecting a resin into a mold by driving a plunger downward in a pot, comprising: an electric plunger driving circuit comprising: an electric motor (3), counting means (10) for counting the number of rotation of the output shaft of the electric motor (3), and a control unit (12) which previously stores a primary maximum current and a secondary maximum current (i max2 ) smaller than the primary maximum current as upper limits of current to be supplied to the electric motor, and a predetermined number of rotation of the output shaft of the electric motor, starts controlling the operating speed of the electric motor (3) when a switch for actuating the electric motor (3) to drive the plunger (5) downward is closed, limits the maximum current to be supplied to the electric motor (3) to the primary maximum current, limits the maximum current to be supplied to the electric motor (3) to the secondary maximum current after the number of rotation of the output shaft of the motor (3) has increased to the predetermined number of rotation, and controls the torque of the electric motor (3) after the secondary maximum current has been selected as the maximum current to be supplied to the electric motor; and a speed reducing and motion converting mechanism (4) coupled with the electric motor, for transmitting the rotary motion of the output shaft of the electric motor (3) after reducing the input rotating speed and converting the input rotary motion into a linear output motion to the plunger (5) to drive the plunger (5) downward.

Claim 12

A transfer molding apparatus for injecting a resin into a mold by driving a plunger downward in a pot, comprising: an electric plunger driving circuit comprising: an electric motor (3), counting means (10) for counting the number of rotation of the output shaft of the electric motor (3), and a control unit (12) which previously stores a primary maximum current and a secondary maximum current (i max2 ) smaller than the primary maximum current as upper limits of current to be supplied to the electric motor, and a predetermined number of rotation of the output shaft of the electric motor, starts controlling the operating speed of the electric motor (3) when a switch for actuating the electric motor (3) to drive the plunger (5) downward is closed, limits the maximum current to be supplied to the electric motor (3) to the primary maximum current, limits the maximum current to be supplied to the electric motor (3) to the secondary maximum current after the number of rotation of the output shaft of the motor (3) has increased to the predetermined number of rotation, and controls the torque of the electric motor (3) after the secondary maximum current has been selected as the maximum current to be supplied to the electric motor; and a speed reducing and motion converting mechanism (4) coupled with the electric motor, for transmitting the rotary motion of the output shaft of the electric motor (3) after reducing the input rotating speed and converting the input rotary motion into a linear output motion to the plunger (5) to drive the plunger (5) downward.

Claim 13

A transfer molding process for sealing an electronic device in a resin by driving a plunger downward in a pot to inject the resin into a mold, characterized in that the rotary motion of the output shaft of the electric motor is transmitted to the plunger to drive the plunger downward after being converted into a linear motion, that the displacement of the plunger is detected continuously while the plunger is driven downward, and the pressure applied to the plunger for driving the plunger downward is changed upon the increase of the displacement of the plunger to a predetermined displacement.

Claim 14

A transfer molding process for sealing an electronic device in a resin by driving a plunger downward in a pot to inject the resin into a mold, characterized in that the rotary motion of the output shaft of the electric motor is transmitted to the plunger to drive the plunger downward after being converted into a linear motion, that the displacement of the plunger is detected continuously while the plunger is driven downward, and the pressure applied to the plunger for driving the plunger downward is changed upon the increase of the displacement of the plunger to a predetermined displacement.

Claim 15

A transfer molding process according to Claim 8, wherein a comparatively high pressure is applied to the plunger until the displacement of the plunger increases to the predetermined displacement, and a comparatively low pressure is applied to the plunger after the displacement of the plunger has increased to the predetermined displacement.

Claim 16

A transfer molding process according to Claim 8, wherein the maximum current defining the upper limit of current to be supplied to the electric motor is changed to change the pressure to be applied to the plunger.