JPS63227028A - Manufacture of resin-sealed electronic component - Google Patents

Abstract

PURPOSE:To shorten molding time by forming a component in first step of pouring molding resin under high pressure to fill a metal mold, second step of switching to low pressure immediately before resin pressure is abruptly increased in the mold, and third step of returning to the high pressure after the resin is poured in the mold. CONSTITUTION:The primary pressure of an external application pressure curve A is reduced to a secondary pressure curve D immediately before the internal pressure of an internal resin to pressure curve B is gradually increased with molding time for resin fill up at time C, i.e., slightly before the time C. Further, when a resin material is poured in a metal mold, it is raised to a tertiary pressure curve E. The molding time can be shortened by switching the pouring pressure between high pressure pouring and low pressure pouring to obtain a resin-sealed electronic component which does not undergo deformation and damage at an electric element and wirings.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a resin-sealed electronic component for use in electrical equipment, electronic equipment, etc., in which the periphery of an electric element is encapsulated with a synthetic resin.

BACKGROUND OF THE INVENTION Conventionally, injection molding machines and transfer molding machines have been used for resin-sealed electronic parts because they are small-sized parts.

Problems to be Solved by the Invention In the prior art, the molded product (41) at the end of the runner
J-type electronic parts are injected at a higher speed and pressure than the molded parts in the center of the runner, causing problems such as deformation and distortion of electrical elements and frequent deformation and disconnection of wire connections.

For this reason, low-pressure molding is performed by using synthetic resins with low viscosity or by lowering the injection pressure during molding, but these methods do not allow the use of high-performance synthetic resins, and the molding time is long ( However, there were disadvantages such as the occurrence of voids.

Furthermore, if we look at the problems of the prior art in detail, Figure 2 is a relationship diagram showing the relationship between the injection of resin material into the molding die in transfer molding, the molding time until it hardens, and the injection pressure. Contrary to the fact that the internal pressure in the mold gradually increases as shown in the internal resin pressure curve B in the same figure, the injection pressure in the applied pressure curve A remains constant until the resin material is completely absorbed in the gate seal and molded product. Until curing, the pressure in the curve A is maintained at a high pressure even after point C in the figure, which is the point at which the cavity of the molding die is filled with the required resin material. Therefore, deformation and distortion of delicate and minute electronic elements, deformation of wiring parts, and disconnection are unavoidable.
Furthermore, since a large amount of inorganic filler is mixed into the synthetic resin material for sealing in order to improve heat resistance and dimensional stability, the above-mentioned tendency for deformation and damage is further increased.

Means for solving the problem of assembly point The present invention provides a first step of injecting the resin at high pressure in the process of filling the molding mold with the resin when molding a resin-sealed electronic component. A resin-sealed electronic component comprising a second step in which the pressure of the injected resin is switched to low pressure immediately before the filling is completed, and a third step in which the resin is injected into the mold, and then the pressure is immediately returned to the high pressure after the mold is filled and molded. This is a manufacturing method.

According to the present invention, during the process in which the electrical element is easily deformed by the injected resin in the mold, that is, in the process until the mold is filled, the pressure of the injected resin is kept low to deform the electrical element to be sealed inside. By surrounding the mold with a resin with low injection pressure, and then increasing the injection resin pressure when the inside of the mold is completely filled with the resin to be injected, deformation and damage to the internal electric elements can be eliminated, and the molding and curing process can be improved. Then, the resin to be injected is also kept at high pressure,
The generation of voids is suppressed.

Example Next, the present invention will be described in detail by way of examples.

Regarding the molding resin injected into the specified mold,
To explain the relationship between molding time and injection pressure in the same mold using Figure 2, the internal pressure of internal resin pressure curve B gradually increases with molding time, relative to the primary pressure of the externally applied pressure curve. The pressure is then lowered to the second pressure curve just before C in the same figure, that is, slightly before C. By doing so, the process proceeds at a relatively low pressure after C, where pressure is applied to the electric element, and deformation and damage to the electric element can be prevented. Furthermore, reducing the injection pressure to a low pressure as a secondary pressure just before the cavity in the mold is filled with the resin material prevents deformation and damage to electrical elements, deformation and disconnection of wire connections. At the same time, it also has the advantage of significantly shortening the molding time.

Further, when the molding die is filled with the resin material, the pressure is increased to the third pressure curve E.

By doing so, the air remaining inside the cavity is expelled to the outside of the cavity, and furthermore, the voids contained in the resin material are shortened, reduced in size, or eliminated.

To give an example and describe the effects of the example, when an electric element is encapsulated with a thermosetting epoxy resin molding material by transfer molding, a 144-cavity mold is used, the mold temperature is 180°C, and the injection pressure is 100 kg/c-, and just before the resin material fills into the mold cavity, increase the injection pressure to 20 kg/c-.
kg/cri, and after filling the cavity with the resin material, the injection pressure was changed to 70k (/c-), resulting in a resin seal with no deformation or distortion of the electrical element, no disconnection, and no voids. 144 stop-type electronic components were obtained.

As a reference, using the same material and mold, the injection pressure was 70 kg/° from the beginning using the conventional method. When molded as d, 4 defective products with damaged electrical elements and 24 defective products with deformed wiring parts occurred. From this point of view, the effectiveness of this embodiment is significantly large.

Effects of the Invention As described above, according to the present invention, the molding time can be shortened by switching the injection pressure between high-pressure injection and low-pressure injection, and resin-sealed electronics can be manufactured without deformation or damage to electric elements or connection parts. parts can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between molding time and injection pressure in transfer molding according to an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between molding time and injection pressure in transfer molding according to a conventional method. A: External applied pressure curve, B: Internal resin pressure curve, C: When the cavity is filled with the required resin material, D: ...Second pressure curve, E...Third pressure curve. Name of agent Patent attorney Toshio Nakao 1 person Figure 1 K sentence 1 mil rod edge (Sentano Figure 2 Molding Time opening (seconds)

Claims (1)

[Claims] In the process of filling the mold with molding resin when molding resin-sealed electronic components, a first step of injecting it at high pressure;
A resin-sealed mold characterized in that molding is performed through a second step of switching to a low pressure immediately before the resin pressure increases rapidly in the mold, and a third step of returning to the high pressure after filling the mold with the resin. Method of manufacturing electronic components.