JP5724266B2 - Thermosetting resin injection molding method - Google Patents

Description

  The present invention relates to a thermosetting resin injection molding method, and more particularly to a mold temperature control method during injection molding.

  In general, when a product is manufactured using a thermosetting resin, a molding die that is manufactured in advance corresponding to the shape of the product is heated while heating the thermosetting resin as a material to some extent. A product as a molded product is manufactured by injecting a thermosetting resin into a molding die and curing it.

  Patent Document 1 discloses a characteristic diagram showing the relationship between the heating time and viscosity of a thermosetting resin. When a thermosetting resin is heated, its viscosity decreases with time, and when the viscosity is minimum. However, it is disclosed that the conditions are optimum for injection, and when the optimum injection conditions are passed, the viscosity gradually increases and the viscosity increases.

  Patent Document 2 discloses a technique for mounting a lead frame on which a semiconductor chip is mounted in a transfer molding die and press molding with a thermosetting resin as a method for manufacturing a semiconductor device. It has been pointed out that if the viscosity of the resin is too low, air is entrained during filling and a defect occurs. Therefore, the semiconductor is devised so as to reduce the filling speed by forcibly cooling so that the mold temperature is lowered during filling, and performing temperature control such that the mold temperature is returned to the temperature before cooling after filling. A technique for resin-sealing a device is disclosed.

Japanese Patent Laid-Open No. 11-192646 (FIG. 2, paragraph numbers 57-61) Japanese Patent Laid-Open No. 03-129839 (FIG. 1, description of examples)

As disclosed in Patent Document 1, the viscosity of the thermosetting resin changes with time. However, Patent Document 1 assumes that the temperature of the mold itself is constant, and there is room for improvement in terms of further improving productivity by shortening the curing rate after resin filling. In addition, as disclosed in Patent Document 2, even when the mold is returned to its original state after cooling, there is a problem that the curing time becomes long and the productivity is poor.
The thermosetting resin has a characteristic that the change in the viscosity of the resin with time varies depending on the temperature. For example, as the temperature of the thermosetting resin increases, the rate of change in viscosity with respect to time increases and the curing time decreases. However, since the time for maintaining the low viscosity is shortened when the thermosetting resin is heated to a high temperature, an injection operation that must be completed during the low viscosity needs to be performed at high speed.

  However, if the speed of the injection operation is increased, problems such as a wire flow such as deformation or cutting of the bonding wire and a problem of bubbles being mixed inside the resin occur, and therefore the speed of the injection operation cannot be increased.

  The present invention has been made in view of the above-mentioned problems, and a main object thereof is to provide a thermosetting resin injection molding method with improved productivity.

  During injection control, the mold is controlled to a temperature at which the thermosetting resin maintains a low-viscosity state, and after the completion of the injection, the mold is controlled to a temperature that promotes resin curing. In the molding method, the injection completion time is obtained from the relationship between the temperature of the mold, the viscosity of the resin, and the time, and is characterized by the time when the resin starts to harden.

  While improving the molding state of resin sealing, the production time per molded product can be shortened.

The typical sectional view showing the composition of the metallic mold in the injection molding device concerning a 1st embodiment of the present invention is shown. The flowchart explaining the injection molding method concerning the 1st Embodiment of this invention is shown. The characteristic view for demonstrating the relationship between the mold temperature concerning the 1st Embodiment of this invention, the viscosity of thermosetting resin, and time is shown. The characteristic diagram for demonstrating the process of the thermosetting resin concerning the 1st Embodiment of this invention, and the relationship between time and a viscosity is shown.

  Next, a first embodiment of the present invention will be described in detail with reference to the drawings.

  Referring to FIG. 1, a molding apparatus based on an injection molding method according to a first embodiment of the present invention includes an upper mold 2 of a mold, a lower mold 7 of a mold, a plunger 8, a temperature control means 9, and an injection control. Means 10, shaft 11, and lower mold position control means 12 are provided. The upper die 2 and the lower die 7 are respectively provided with an upper cavity component 1 and a lower cavity component 4 having a package-shaped cavity 5. An integrated circuit (IC) chip mounting substrate 3 connected by bonding wires is disposed in the package-shaped cavity 5 of the lower mold 7.

  Each of these means operates as follows.

  The temperature control means 9 such as a heater heats the upper mold 2 and the lower mold 7 after the injection completion time 14 has elapsed, and further raises the mold temperature at the completion of the injection.

  It will be described with reference to the characteristic diagram shown in FIG. 3 that the relationship between the viscosity of the thermosetting resin according to the first embodiment of the present invention and the passage of time varies depending on the mold temperature. FIG. 3 shows how the viscosity of the thermoplastic resin changes with time when the mold temperatures are 170 ° C., 175 ° C., 180 ° C., and 185 ° C., respectively. When the mold temperature is constant at 170 ° C., the low viscosity period is stably long as indicated by the dotted line at 170 ° C., and the curing rate is slow. On the other hand, when the mold temperature is as high as 185 ° C., the low viscosity period is short, but the curing speed is fast. Thus, it can be seen that the viscosity of the thermoplastic resin can be controlled by controlling the mold temperature.

  In the present invention, the injection completion time 14 of the thermosetting resin is the time when the resin viscosity starts to rise after reaching the minimum viscosity in the relationship between the mold temperature, the resin viscosity and the elapsed time as shown in FIG. To do. Preferably, the time point at which the resin viscosity increases by 10% with respect to the minimum viscosity of the resin is set as the injection completion time 14. Therefore, the injection completion time 14, that is, the resin curing start time of the present invention is determined based on the relationship between the mold temperature, the viscosity of the thermosetting resin, and the elapsed time.

  The injection control means 10 is means for injecting the thermosetting resin by raising the position of the plunger 8 after the injection start time 13 has elapsed.

  The injection start time 13 is a time when the thermosetting resin reaches the minimum viscosity in the relationship between the mold temperature, the resin viscosity, and the time as shown in FIG. Therefore, the injection start time 13 is determined based on the relationship between the mold temperature, the viscosity of the thermosetting resin, and the time.

  The lower mold position control means 12 is a means for putting the thermosetting resin into the pod 6, then raising the position of the lower mold 7, aligning with the upper mold 2, and clamping the mold. At the same time, after the thermosetting resin in the package-shaped cavity 5 is completely cured, the lower mold 7 is lowered to open the mold.

  Next, the operation of the first exemplary embodiment of the present invention will be described in detail with reference to the flowchart of FIG.

  First, by controlling the mold temperatures of the upper mold 2 and the lower mold 7 by the temperature control means 9, for example, the temperatures of the upper mold 2 and the lower mold 7 are maintained at 175 ° C. to 180 ° C. (S1).

  Next, a thermosetting resin is put into the pod 6 of the lower mold 7 (S2).

  Next, the lower mold position is controlled by raising the position of the lower mold 7 by the lower mold position control means 12, and at the same time, the thermosetting resin is melted by preheating until 10 seconds (injection start time 13), for example, as shown in FIG. And lowering the viscosity (S3). As represented by the curve shown by the dotted line in FIG. 4, the period of low viscosity can be stably maintained.

  Next, after the injection start time 13 has elapsed, the position of the plunger 8 is raised by the injection control means 10 to inject a thermosetting resin (S4). When the thermosetting resin with reduced viscosity is injected, since the thermosetting resin is melted, the resin flows from the pod 6 and fills the package-shaped cavity 5 with the resin. The dotted line in FIG. 4 corresponds to the viscosity curve of 175 degrees in FIG. In a state where the thermosetting resin is stably low in viscosity, the thermosetting resin is caused to flow into the package-shaped cavity 5, so that the resin fluidity in the package-shaped cavity 5 is improved and the resin-sealed molding is performed. Generation | occurrence | production of the unfilled location of goods can be suppressed. Therefore, the molding state of resin sealing can be further improved.

  Next, after the time when the thermosetting resin in the package-shaped cavity 5 starts to cure, for example, 20 seconds (injection completion time 14) as shown in FIG. 4, the temperature control means 9 causes the upper mold 2 and the lower mold 7 to be cured. By rapidly heating the temperature to, for example, 185 ° C. to 190 ° C., as shown by the viscosity curve shown by the solid line in FIG. 4, curing of the thermosetting resin is promoted and the curing time is shortened (S5).

  That is, in this embodiment, the injection is completed in the low viscosity region of the 175 ° C. viscosity curve, the temperature of the mold is controlled to 185 ° C. after the injection is completed, the resin is accelerated, and the curing time is shortened. In other words, the viscosity curve shown in FIG. 4 becomes the 175 ° C. viscosity curve shown in FIG. 3 until the injection completion time 14, and becomes the 185 ° C. viscosity curve shown in FIG. 3 after the injection completion time 14. Thus, FIG. 4 and FIG. 3 have a relative relationship.

  Next, the lower mold position control means 12 lowers the position of the lower mold 7 to open the mold (S6).

  Finally, the molded product is taken out from the mold cavity (S7).

  As described above, according to the present invention, the temperature of the mold is controlled according to the viscosity characteristics of the thermosetting resin and the curing of the thermosetting resin is promoted, so that the production time per molded product can be shortened, Can be improved.

  In the first embodiment of the present invention, the mold temperature of both the upper mold 2 and the lower mold 7 is controlled by the temperature control means 9 based on the relationship between the mold temperature, the viscosity of the thermosetting resin, and the time. In this way, the injection can be started at the time when the viscosity curve of the thermosetting resin reaches the minimum viscosity, the flowability of the resin can be improved, and the molding time of the thermosetting resin can be shortened. Can be controlled. Therefore, not only the productivity is improved, but the molding state of the resin sealing can be further improved.

  In the first embodiment of the present invention, as the characteristics of the thermosetting resin, as the mold temperature becomes higher, the rate of change in viscosity of the thermosetting resin with respect to time increases, and the curing time of the thermosetting resin increases. In the case of having a characteristic of shortening, the case where the curing of the thermosetting resin can be promoted by heating the upper mold 2 and the lower mold 7 by the temperature control means 9 after the completion of the injection completion time 14 has been described.

  It is also possible to employ a thermosetting resin having a temperature characteristic opposite to that of the first embodiment. That is, as the second embodiment of the present invention, as the characteristics of the thermosetting resin, the lower the mold temperature, the larger the viscosity change rate of the thermosetting resin with respect to time. When the curing time is shortened, the curing of the thermosetting resin can be promoted by cooling the upper mold 2 and the lower mold 7 with the temperature control means 9 after the injection completion time 14 has elapsed.

  Specific examples of the thermosetting resin in the above-described embodiment include a model made by Kyocera Chemical Co., Ltd .: KE-G1250LKDS, and a model made by Sumitomo Bakelite Co., Ltd .: G600F Type B.

  The present invention can also be applied to applications such as a coating device for coating a thermosetting resin and a control means for coating the coating device at high speed.

DESCRIPTION OF SYMBOLS 1 Upper cavity structure part 2 Upper mold | type 3 IC chip mounting substrate 4 Lower cavity structure part 5 Package-shaped cavity 6 Pod 7 Lower mold 8 Plunger 9 Temperature control means 10 Injection control means 11 Shaft 12 Lower mold position control means 13 Injection start time 14 Injection completion time

Claims (3)

Using the viscosity curve obtained from the relationship between the temperature of the mold, the viscosity of the thermosetting resin, and the heating time of the thermosetting resin, the timing at which the thermosetting resin reaches the minimum viscosity is obtained, and the obtained timing injection starting from turned, the injection control of the thermosetting resin is a mold to a temperature to maintain the low viscosity state temperature control, after completion of injection time curing of the thermosetting resin to promote in the injection molding method of the thermosetting resin to a temperature control mold temperature, the injection completion time is determined based on the viscosity curve, wherein the thermosetting resin is a time to start hardening Thermosetting resin injection molding method. The characteristics of the thermosetting resin, as the temperature of the mold becomes high, the viscosity change rate of the thermosetting resin becomes large with respect to time, has a curing time is shortened characteristics of the thermosetting resin , after the completion of the injection time, the injection molding method of the thermosetting resin according to claim 1, characterized in that to accelerate the curing of the thermosetting resin by heating by the temperature control means to the mold . The thermosetting resin injection molding method according to claim 1 or 2, wherein an IC chip mounting substrate connected by a bonding wire is disposed in the mold.

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