JP2002219740A - Apparatus and method for resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a void remains in a resin or a fault of an external appearance occurs in some cases when a space between leads is narrow, in an apparatus wherein a buffer sheet is brought into contact with one surface of a lead frame and held by upper and lower tools between and resin molding is conducted with parts of the leads made to project a little along the outer surface of an exterior resin. SOLUTION: In the apparatus for resin molding, the buffer sheet 13 is brought into contact with the non-mounting surface side of an electronic component main body 1 of the lead frame 2 and held by a pair of tools 9 and 14 between and the principal part on the lead frame 2 including the electronic component main body 1 is coated with the resin 8. The apparatus is equipped with a tool driving part 20 which controls clamping of the paired tools 9 and 14 in a stepped manner substantially and with a resin supply driving part 27 which increases gradually the injection pressure of the resin 8 in the initial clamping period and controls the injection pressure so that it be the maximum in the later clamping period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding apparatus and a resin molding method for coating a main portion of a lead frame including an electronic component body mounted on the lead frame with a resin, and more particularly to an electronic component suitable for surface mounting. A suitable resin molding apparatus and resin molding method are provided.

[0002]

2. Description of the Related Art Small and portable electronic circuit devices, such as video cameras, notebook personal computers, and mobile phones, are required to be reduced in size and weight, and electronic components used in these devices are also required to be reduced in size and weight. Has been requested. An example of such an electronic component is shown in FIGS. In the figure, 1 is an electronic component body such as a semiconductor pellet, 2
Is a lead frame in which an island 3 on which the electronic component body 1 is mounted and a plurality of, in the illustrated example, a set of four leads 4 are integrated, and the lead 4 connects one lead 4a to the island 3. One end of each of the other leads 4b, 4c and 4d is arranged near the island 3, and the intermediate portion and the outer end are connected and integrated by connecting strips 5 and 6. 7a, 7
b and 7c are wires for electrically connecting electrodes (not shown) on the electronic component body 1 to one ends of the leads 4b, 4c and 4d, and 8 is a main wire on the lead frame 2 including the electronic component body 1. The resin covered and covered with a part is shown. In this electronic component intermediate structure, the connecting strips 5 and 6 exposed from the resin 8 are cut and removed, and if necessary, the leads 4 are cut in the vicinity of the resin 8 so that each lead 4 is made independent to obtain an individual electronic component. Can be

In this electronic component, the leads 4 are exposed from the outer surface of the resin 8 and the exposed portions of the leads 4 are projected from the outer surface of the resin 8 as shown in FIG. Good surface mountability. Also, like the lead 4, the island 3 is exposed and protruded from the outer surface of the resin, so that the mountability is improved, and the heat generated by the electronic component body 1 during operation is improved.

FIG. 8 shows an example of an apparatus for coating the lead frame 2 with a resin. In the figure, reference numeral 9 denotes a lower die, which supports the lead frame 2 on the upper surface thereof and also accommodates the island 3 and a part of the lead 4; a gate for supplying fluidized resin to the cavity 10; The air vent 12 which discharges the air compressed by the resin supplied to the air supply is formed. The air vent 12 is formed in the connecting strip 5 located between the leads 4 of the lead frame 2. Reference numeral 13 denotes a buffer sheet that covers the lower die 9 on which the lead frame 2 is mounted, and reference numeral 14 denotes an upper die having a flat lower surface, which sandwiches the lead frame 2 together with the lower die 9 via the buffer sheet 13.

This device mounts an electronic component body 1 on a lower mold 9 and wire-bonds a lead frame 2.
After covering the top with the buffer sheet 13 and holding the lead frame 2 between the upper and lower molds 9 and 14, the buffer sheet 13 compressed between the upper and lower molds 9 and 14, the island 3 and the lead 4 portion is provided. Is a bulging cavity 10
Protrude into. When the resin 8 is supplied into the cavity 10 in this state, the buffer sheets 13 for the islands 3 and the leads 4 are provided.
The resin 8 does not adhere to the surface in contact with the resin, thereby preventing the occurrence of resin burrs. The main part of the lead frame 2 is coated with a resin in a state where the main part of the lead frame 2 is slightly depressed from the opening surface of the cavity 10 by the projecting portion of the buffer sheet 13. Therefore, the outer surfaces of the islands 3 and the leads 4 are exposed in a state of being relatively protruded from the outer surface of the resin 8, and the electronic component shown in FIG.

This type of electronic component is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-3
No. 4699 (prior art). This prior art lead frame has no island and one end of the lead is directly connected to the electronic component body, but the buffer sheet is placed not only on the upper mold side but also on the lower mold including the inside of the cavity. By doing so, the electronic component main body can be covered with the resin without causing resin burrs on the back surface of the electronic component main body exposed from the exterior resin and both surfaces of the leads.

[0007]

By the way, in the case of surface-mounted electronic components having an outer diameter of several mm, the width and spacing of the leads must be reduced. Also, even for relatively large electronic components having an outer diameter of more than 10 mm, if the number of leads is large, it is necessary to reduce the width of the leads and the arrangement interval of the leads. In order to reduce the width and interval of the leads, the thickness of the leads 4 must be reduced. In such a narrow lead frame in which the leads are close to each other, the area ratio of the lead portion to the lead area is large. Therefore, the amount of compression of the buffer sheet 13 in the lead area increases, and the amount of swelling between the leads also increases. On the other hand, the bulging buffer sheet 13 is pushed between the leads 4, but since the lead portion is relatively thin, the space between the leads 4 located in the cavity 10 is closed as shown in FIG.

When the buffer sheet 13 is inserted between the leads 4 as described above, the air vent 12 formed in the connecting strip 5 is formed.
Is substantially long, and the opening area thereof is narrowed, so that there is a problem that the air in the cavity 10 is obstructed. When the air vent 12 is closed and the air remaining in the cavity 10 is compressed in this manner, the supply of the resin to the cavity 10 becomes insufficient due to this pressure,
There is a problem in that air remains in the resin supplied into the cavity 10 to form air voids, and when the air voids are exposed on the outer surface of the resin 8, the appearance becomes poor. When the bulging amount of the buffer sheet 13 becomes excessive, the bulging lower end 13a of the buffer sheet 13 enters the cavity 10 from the lower surface of the lead 4 as shown in FIG. In addition, there is a problem that not only the groove is formed, but also the adhesion strength between the lead 4 and the resin 8 is reduced, the moisture resistance is reduced, and the appearance is poor.

[0009]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, and has an island in which an electronic component body is mounted on one surface, and an island disposed at one end near the island, on the electronic component body. A lead frame in which a plurality of leads electrically connected to electrodes are integrated with the surface of the island where the electronic component body is not mounted and the leads are flush with each other, and the electronic component body of the island is mounted. In a resin molding apparatus in which a buffer sheet is brought into contact with a non-surface side, sandwiched between a pair of dies, and covering a main part on a lead frame including an electronic component body with a resin, the pair of dies are substantially stepped. A mold driving unit that controls the mold clamping in a shape, and a resin supply drive that gradually increases the injection pressure of the resin during the initial mold clamping period and controls the injection pressure to maximize the injection pressure during the later mold clamping period To provide a resin molding apparatus characterized in that comprises and.

The present invention also relates to an island having an electronic component body mounted on one surface, and a plurality of leads arranged at one end near the island and electrically connected to electrodes on the electronic component body. A lead frame with the surface where the component main body is not mounted and the lead are made flush with each other, and a buffer sheet is brought into contact with the surface of the island where the electronic component main body is not mounted, and is sandwiched between a pair of molds. In a resin molding method for covering a main part on a lead frame including an electronic component body with a resin, the pair of molds is controlled to be substantially stepwise in mold clamping, and the injection pressure of the resin is set in an initial mold clamping period. And a resin molding method characterized in that the injection pressure is controlled so that the injection pressure is maximized in a later mold clamping period.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin molding apparatus and a resin molding method according to the present invention are to mold a resin by bringing a buffer sheet into close contact with a lead or the like. And a resin supply drive unit that controls the injection pressure so that the injection pressure of the resin is gradually increased in the initial mold clamping period and the injection pressure is maximized in the later mold clamping period, and the mold clamping pressure is shifted in time. Supply the fluidized resin into the cavity at a stage where the mold clamping pressure is low, and raise the mold clamping pressure and increase the resin injection pressure when the cavity is almost filled with resin. Thereby, the air remaining in the cavity can be reliably expelled, and the bulging portion of the buffer sheet can be prevented from being excessively pushed between the leads. In addition, the injection pressure can be controlled so that the resin supplied into the mold comes into contact with the buffer sheet located between the leads during the initial mold clamping period. Further, the mold clamping control and the injection pressure control are set according to the thickness of the lead, so that an optimum resin molding can be performed according to the model of the lead frame.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the figure, the same components as those in FIG. In this resin molding apparatus, the electronic component body 1 is mounted on a lower mold 9 in which a cavity 10, a gate portion 11, and an air vent 12 are formed, and the electronic component body 1 and the leads 4 are electrically connected via wires 7. The lead frame 2 is placed with the island 3 and a part of the lead 4 disposed in the cavity 10, the lead frame 2 is covered with a buffer sheet 13, the upper mold 14 is lowered, and the buffer sheet 13 is lowered. Is brought into close contact with the islands 3 and the leads 4, and a part of the buffer sheet 13 compressed between the islands 3 and the leads 4 and between the leads 4 is expanded so that the outside of the resin 8 supplied to the cavity 10 is increased. It is the same as the device in FIG. 8 in that the island 3 and the lead 4 are exposed from the surface without forming a thin resin flash.

In the figure, reference numeral 15 denotes a plurality of guide rods, 16 denotes a movable plate which is inserted into the guide rod 15 and moves up and down, and 17 denotes a fixed plate which is inserted through the guide rod 15 and fixed above the movable plate 16. 16 has a lower mold 9 on the upper surface of the fixed platen 1.
An upper die 14 is fixed to a lower surface of the upper die 8. Reference numeral 18 denotes a hydraulic cylinder that supports the movable platen 16 and moves up and down. Reference numeral 19 denotes a hydraulic cylinder drive unit that is connected to the hydraulic cylinder 18 by a hydraulic pipe 19a to drive the cylinder 18.
The mold drive unit 20 that controls the clamping of the pair of molds 9 and 14 in a substantially stepwise manner is constituted by the hydraulic cylinder drive unit 19 including the hydraulic pipe 8 and the hydraulic pipe 19a. As shown in FIG. 2, a pot 22 for accommodating the resin tablet 21 penetrates through the lower mold 9, and a plunger 23 that is inserted into the pot 22 from below and pressurizes and fluidizes the resin tablet 21 in the pot 22 is arranged. Then, the surface of the lower mold 9 is moved from the pot 22 to the gate portion 1.
A runner 24 for guiding the resin fluidized to 1 is formed. Reference numeral 25 denotes a plunger driving cylinder that is disposed below the lower mold 9 and drives the plunger 23. Reference numeral 26 denotes a plunger driving cylinder 25 that is connected to the plunger driving cylinder 25 by a hydraulic pipe 26a. 4 shows a plunger driving unit for controlling operation. Plunger drive cylinder 25, hydraulic pipe 26
The resin supply drive unit 27 is constituted by the plunger drive unit 26 including the “a”. Numerals 28 and 29 denote spools for feeding and winding the buffer sheet 13. The buffer sheet 13 fed from one of the spools 28 is disposed below the fixed platen 17 in the upper mold 1.
4 and is taken up by another spool 29. This apparatus is provided with a heating means for heating the dies 9 and 14, a loader and an unloader for supplying the lead frame 2 and the resin tablet 21 and taking out the lead frame 2 after resin molding, but is not shown.

By explaining the operation of the apparatus, the resin molding method according to the present invention will be described. First, the upper and lower molds 9 and 14 are opened, the electronic component body 1 is mounted on the cleaned lower mold 9, and the lead frame 2 on which wire bonding has been completed is supplied to the cavity 10 position. Almost at the same time, the resin tablet 21 is supplied into the pot 22 in which the plunger 23 is lowered, and is heated by radiant heat from the mold. In this state, when the mold driving unit 20 is operated and the movable plate 16 is raised by the hydraulic cylinder 18, the lower mold 9 approaches the upper mold 14 through the buffer sheet 13. 9 and 14 are brought into close contact with the buffer sheet 13 via the lead frame 2 to form a mold clamping state, and the buffer sheet 13 seals the opening of the cavity 10 via the lead frame 2. Operation start (time t0)
From this to the stage (time t1), the mold driving unit 20
As shown by the dotted line A in FIG. 2, the mold clamping pressure is an intermediate pressure between the maximum values PMmax, and is set to a pressure PM1 at which the buffer sheet 13 comes into close contact with the lead frame 2 and is slightly compressed. When the pressure PM1 is reached, the mold driving section 20 holds the pressure. On the other hand, from time t1, the resin supply driving unit 2
The operation of 7 is started, and the heated resin tablet 21 is softened by being pressed by the plunger 23, and the resin which has been fluidized by pressing is sent from the pot 22 into the cavity 10 through the runner 24 and the gate 11. The pressure (injection pressure) of the resin is maintained at a constant slope from time t1, as shown in FIG. In this state, an opening of the air vent 12 is secured between the leads 4 and 4 as shown in FIG. 4, and the air compressed by filling the resin into the cavity 10 is sequentially discharged from the air vent 12 to the outside of the mold. . Then, as time elapses and approaches time t2 at which the resin is filled into the cavity 10, the supply of the resin from the gate unit 11 reaches its limit. Next, the setting of the mold driving unit 20 is changed from the time t2, and the maximum value PMmax of the mold clamping pressure is changed as shown in FIG.
And the setting of the resin supply drive unit 27 is changed to set the resin injection pressure to a predetermined maximum value PRmax. In this apparatus, the supply of the resin to the cavity 10 is almost completed, and the mold driving unit 2
In order to set the mold clamping pressure of the mold by 0 to the maximum, the buffer sheet 13 is set at the maximum mold clamping pressure at the open end of the cavity 10 because the resin filled in the lead frame 2 or the cavity 10 is in close contact with the entire surface. However, the buffer sheet 13 is only compressed and cannot enter between the leads or between the island and the lead. As described above, since no voids remain in the resin and no undesired concave portions are formed on the surface of the exterior resin, it is possible to manufacture an electronic component having good appearance and moisture resistance.

In the resin molding apparatus and the resin molding method according to the present invention, the setting of the mold clamping pressure, the holding time thereof, and the injection pressure is appropriately set according to the thickness of the lead, so that the width of the lead and the arrangement interval of the lead are small. An electronic component having a good appearance without voids and a good moisture resistance can be manufactured even with a small electronic component.

[0016]

As described above, according to the present invention, there is provided an electronic component using a lead frame, wherein a part of the lead is projected from the outer surface of the exterior resin by using a buffer sheet. In addition, the generation of voids due to the buffer sheet can be prevented, and an electronic component having a good appearance and good moisture resistance can be realized without forming an undesired concave portion between the leads.

[Brief description of the drawings]

FIG. 1 is a side view of a resin molding apparatus according to the present invention.

FIG. 2 is a sectional side view of a main part of the resin molding apparatus shown in FIG. 1;

FIG. 3 is an operation explanatory diagram showing a time change of a mold clamping pressure and an injection pressure for explaining the operation of the apparatus in FIG. 1;

FIG. 4 is a sectional view of a main part of the apparatus of FIG. 1, illustrating a resin mold state of the apparatus of the present invention.

FIG. 5 is a partially transparent plan view showing an example of an electronic component intermediate structure.

6 is a side sectional view of the intermediate structure shown in FIG.

FIG. 7 is a bottom view of the intermediate structure shown in FIG. 5;

8 is a side sectional view of a main part of an apparatus for resin-molding the lead frame of the intermediate structure shown in FIG. 5;

9 is a front sectional view showing the problem of the resin molding device shown in FIG.

10 is a side sectional view showing another problem of the resin molding device shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electronic component main body 2 lead frame 3 island 4 lead 5 connecting strip 8 resin 9 lower mold 10 cavity 11 gate section 12 air vent 13 buffer sheet 14 upper mold 18 hydraulic cylinder 19 hydraulic cylinder drive section 20 mold drive section 21 resin tablet 22 Pot 23 Plunger 25 Cylinder 25 Plunger Driving Cylinder 26 Plunger Driving Unit 27 Resin Supply Driving Unit

Claims (4)

[Claims] An electronic component main body of an island includes an island having an electronic component main body mounted on one surface thereof, and a plurality of leads arranged at one end near the island and electrically connected to electrodes on the electronic component main body. A lead frame in which the unmounted surface and the lead are made flush with each other, the buffer sheet is brought into contact with the surface of the island where the electronic component body is not mounted, and is sandwiched between a pair of molds,
In a resin molding apparatus for covering a main part on a lead frame including an electronic component body with a resin, a mold driving unit that controls clamping of the pair of dies in a substantially stepwise manner, A resin molding apparatus, comprising: a resin supply drive section for gradually increasing the injection pressure and controlling the injection pressure so that the injection pressure is maximized during a later mold closing period. 2. The electronic component body of the island, comprising: an island having an electronic component body mounted on one surface; and a plurality of leads arranged at one end near the island and electrically connected to electrodes on the electronic component body. A lead frame in which the unmounted surface and the lead are made flush with each other, the buffer sheet is brought into contact with the surface of the island where the electronic component body is not mounted, and is sandwiched between a pair of molds,
In a resin molding method for coating a main part on a lead frame including an electronic component body with a resin, the pair of dies are controlled to be substantially stepwise in mold clamping control, and
A resin molding method characterized by gradually increasing the injection pressure of a resin during an initial mold clamping period and controlling the injection pressure so that the injection pressure becomes maximum during a later mold clamping period. 3. The resin according to claim 2, wherein the injection pressure is controlled so that the resin supplied into the mold comes into contact with the buffer sheet located between the leads during an initial mold clamping period. Molding method. 4. The resin molding method according to claim 2, wherein the mold clamping control and the injection pressure control are set according to the thickness of the lead.