JPH0418464B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to an improvement in a resin molding method for a semiconductor element mounted on a lead frame, and particularly relates to a method for molding a semiconductor element using a transfer mold. It is used in the field of molding technology industry where resin molding is performed.

(Prior Art) A basic configuration example of a transfer mold mold for a semiconductor device includes, for example, a fixed upper mold, a movable lower mold disposed opposite to the fixed upper mold, a resin material supply pot, and a mold inside the pot. A heater and a plunger for melting the resin material, a molding cavity portion disposed oppositely between the two molds, and a cull portion, a runner portion, and a gate portion that communicate the inside of the cavity with the pot. There are known devices in which a transfer route and the like are provided. When performing resin molding of semiconductor elements using such conventional molds,
The semiconductor element on the lead frame is set in a predetermined position in the cavity, and both molds are clamped.Next, a resin material is supplied into the pot and melted by heating and pressurizing it. The resin material is injected under pressure into the cavity through the transfer path,
In this way, the semiconductor element is resin molded.

By the way, the pots and
Air remains in the transfer path and the cavity, and if this residual air mixes into the molten resin material within the cavity, voids (bubbles) or Pinholes or missing parts are formed, which causes problems such as lowering the water resistance (humidity) and reliability of the semiconductor molded product and impairing its appearance. However, the conventional method of discharging the residual air utilizes the flow of molten resin material that is transferred under pressure to the cavity side, so it may cause the pressing force of the resin material by the plunger to be increased more than necessary, or the resin material may be damaged. There is a problem that the amount used must be more than the required amount, and when the molten resin material is transferred under pressure, residual air in the transfer path is drawn into the resin material and is injected into the cavity. There is a problem that it is not possible to reliably prevent this, and as a result, it reduces the overall durability of the mold, reduces the effective utilization rate of the resin material, and furthermore,
This method has drawbacks such as the inability to reliably mold high-quality semiconductor molded products.

(Problems to be Solved by the Invention) The present invention efficiently exhausts the air remaining in the transfer path of the molten resin material and the cavity in the transfer mold mold to the outside, so that the remaining air can be removed from the molten resin. The object of this invention is to eliminate the above-mentioned conventional problems caused by the incorporation of residual air by reliably preventing the incorporation of residual air into the material.

The present invention also aims to improve the effective utilization rate of the resin material used and the overall durability of the mold used.

(Means for Solving the Problems) The transfer resin molding method for a semiconductor element according to the present invention involves setting a lead frame on which a semiconductor element is mounted in the cavity portions of both types disposed facing each other. A mold clamping process is carried out for the transfer mold molds for mold matching, then a process is carried out to supply resin material into the mold pot, and then the resin material in the pot is heated and pressurized to melt it. The process of melting the resin material is carried out, and then the molten resin material in the pot is pressurized and injected into the molding cavity through the transfer path consisting of the cull part, runner part, and gate part of the mold. At the same time, this pressurized transfer process is simultaneously carried out through a vacuum process in the transfer route that suctions and removes residual air in the route from the runner section in the transfer route to the outside, and from an air vent communicating with the cavity to the cavity. A vacuuming process is performed inside the cavity to suck out the residual air inside the cavity to the outside, and then a closing process of the transfer path is performed to close the end of the transfer path to prevent the molten resin material from flowing out. Furthermore, after a required resin molding time has elapsed, a mold closing step is performed in which the transfer path is opened and both molds are opened to take out the semiconductor resin molded product to the outside.

(Function) Therefore, in the method of the present invention, the air remaining in the transfer route and the cavity is efficiently and reliably removed, so that the above-mentioned air is removed from the molten resin material transferred under pressure to the cavity side. This prevents residual air from getting mixed in.

In addition, since the closing process at the end of the transfer route prevents the molten resin material from flowing out, the molten resin material that is pressurized and injected into the cavity through the gate of the route is pressurized. The injection action is to be carried out under equal conditions.

(Example) Next, the method of the present invention will be explained based on example diagrams.

FIGS. 1 and 2 show the main parts of a transfer mold mold used when using the method of the present invention, and the mold includes a fixed upper mold 1 and A movable lower mold 2 provided, a supply pot 4 for resin material 3 provided on the upper mold 1 side, and the pot 4
A plunger 5 for pressurizing a resin material fitted into a molding cavity 6 disposed oppositely between the upper and lower molds 1 and 2...
6, a molten resin material consisting of a cull part ₇₁ , a runner part 72, and a gate part ₇₃ , which communicate the cavities 6...6 arranged on the parting line P and L surfaces of the lower die ₂ and the pot 4. , a transfer path 7, heaters and cavities 6 for heating the resin material in the pots 4, and an ejector mechanism (not shown) for the resin molded body molded in the transfer path 7.

Further, at the route end portion ₇₄ of the transfer route 7,
An intake (vacuum) path 8 connected to a vacuum source (not shown) side is opened for communication, and a path terminal portion 7 ₄ (runner section 7) is located closer to the pot 4 than the communication opening 8 ₁ of the intake path. is provided with a stopper mechanism 9 that communicates or closes the pot 4 side and the communication opening ₈₁ of the intake path, and the stopper mechanism includes a stopper ₉₁ made of molten resin material and a stopper mechanism 9 that connects the stopper It is comprised of a hydraulic (pneumatic) device 9 ₂ that moves forward and backward with respect to the path end portion 7 ₄ .

Furthermore, as shown in FIG. 2, an air vent (intake path) 10 connecting the cavity 6 and a vacuum source (not shown) is opened in the cavities 6...6, and the air vent 10 At a position closer to the vacuum source than the communication opening ₁₀₁ ,
A stopper mechanism 11 for communicating or closing the cavity 6 and the vacuum source side is provided, and the stopper mechanism 11 is made of a molten resin material.
₁ , and a hydraulic (pneumatic) device (not shown) that moves the stopper forward and backward relative to the air vent 10.

Note that the reference numeral 12 in the figure indicates a sealing member disposed at the parting lines P and L of both molds 1 and 2.

When performing resin molding of a semiconductor element using the above-mentioned mold, first, the cavities 6...6
A lead frame with a semiconductor element attached thereto is set at a predetermined position in the mold and the mold is clamped.Next, a resin material 3 is supplied into the pot 4, and then the material 3 is heated to a required temperature with a heater. At the same time, as shown in FIG. 3, the molten resin material 31 is pressurized and melted by the plunger 5, and then the plunger 5 is further lowered to transfer the molten resin material ₃₁ to the cavities 6...6 side under pressure. In addition, at the same time as the pressurized transfer of the material 3 ₁ ,
Activate the vacuum source to remove the transfer path 7 and cavity 6.
…The residual air in 6 is transferred to the intake path 8 and air vent 1.
0 to the outside to create a vacuum in the transfer path 7 and the cavities 6...6.

Next, the hydraulic (pneumatic) device 9 ₂ of the stopper mechanism is activated, and the stoppers 9 ₁ and 11 ₁ open the communication opening 8 between the intake passage 8 and the air vent 10 .
_{1.10 1} and the pot 4 side and the cavity 6 _side are closed off, and in this state, as shown in FIG. After the required time has elapsed, the stopper 9 ₁ .
11 ₁ is returned to its original position, the mold is opened, and the semiconductor resin molded product and the cold slag molded in the transfer path 7 are taken out between the molds 1 and 2 by the ejector mechanism.

Note that the above-described descent of the plunger 5 occurs when the molten resin material 3 ₁ is filled into the cull portion 7 ₁ (the third
In the state shown in the figure), the downward movement may be temporarily stopped to more reliably perform the above-described vacuuming process in the moving path 7 and the cavities 6...6. Further, it is preferable that the vacuum step is continued until the plunger 5 is completely lowered (FIG. 4).

In the above-described embodiment, since the transfer path 7 and the cavities 6...6 can be maintained in a vacuum state, it is possible to efficiently and reliably prevent residual air from entering the molten resin material. To reliably prevent the formation of voids, pinballs, or missing parts caused by the residual air on the inside or outside surface of the semiconductor resin molded body molded in the cavities 6...6. It is something that can be done.

Furthermore, in addition to the above-mentioned functions and effects, by preventing the molten resin material 3 ₁ from flowing out, the resin mold is improved by equalizing the pressurized injection conditions for the material 3 ₁ injected into the cavities 6...6 through the gate 7 ₃ . It is possible to achieve uniformity and high quality of the molded product, and
It is possible to reduce the amount of resin material used and improve the effective utilization rate, and furthermore, it is possible to maintain a constant pressure force of the plunger 5 on the resin material 3 (3 ₁ ), thereby improving the durability of the molding die. This has effects such as being able to achieve the desired results.

(Effects of the Invention) According to the method of the present invention, residual air in the mold is not mixed into the molten resin material transferred under pressure, so there are no voids or pinballs inside or on the outer surface of the semiconductor resin molded product. Or, no defects are formed, and therefore, the water resistance (moisture) and reliability of the semiconductor molded product can be significantly improved, and
This has the great effect of making it possible to mold semiconductor molded products with excellent appearance. In addition, by equalizing the pressurized injection conditions of the molten resin material into the cavity and by making the pressing force of the material constant, the quality of semiconductor molded products is improved and the effective utilization rate of the resin material is improved.
In addition, since the durability of the molding die can be improved, the above-mentioned problems of the conventional method can be reliably solved.

[Brief explanation of drawings]

The figures show an embodiment of the method of the present invention, in which Fig. 1 is a partially cutaway vertical sectional view showing the main parts of a transfer mold mold for a semiconductor element, and Fig. 2 is a partially cutaway plan view of the cavity part thereof. FIG. 3, and FIG. 4 are all explanatory diagrams of the operation of the method of the present invention. 1... Upper mold, 2... Lower mold, 3... Resin material, 3
₁ ... Molten resin material, 4... Pot, 5... Plunger, 6... Cavity, 7... Transfer route,
7 ₁ ...Cull part, 7 ₂ ...Runner part, 7 ₃ ...Gate part, 7 ₄ ...Route end part, 8...Intake route, 9
...Stopper mechanism, 10...Air vent, 11
...stopper mechanism.

Claims (1)

[Claims] 1. A lead frame with a semiconductor element attached to it is set in the cavities of both molds arranged facing each other, and a clamping process of the transfer mold mold is performed to match the two molds. Next, the lead frame is placed into the mold pot. Next, a resin material supplying step is carried out in which the resin material in the pot is heated and pressurized to melt it, and then the molten resin material in the pot is poured into the cull part of the mold.・A pressurized transfer step is carried out to inject the molten resin material into the molding cavity through a transfer path consisting of a runner section and a gate section, and at the same time, the molten resin material is injected into the molding cavity through a transfer path consisting of a runner section and a gate section. A vacuum step in the transfer path for sucking and discharging residual air to the outside and a vacuum step in the cavity for sucking and discharging the residual air in the cavity to the outside from an air vent communicated with the cavity are performed, and then the transfer A step of closing the transfer path is performed by closing the end of the path to prevent the molten resin material from flowing out.Furthermore, after the required resin molding time has elapsed, the transfer path is opened and both molds are opened. 1. A transfer resin molding method for a semiconductor element, characterized in that a mold opening step is performed to take out a semiconductor resin molded product to the outside.