JP5699735B2 - Injection molding apparatus and injection molding method - Google Patents

Description

  The present invention relates to an injection molding apparatus and an injection molding method, and more particularly to an injection molding apparatus and an injection molding method for molding a semiconductor, a high-frequency device, and an electronic device with a thermosetting resin.

  The molding process for molding a semiconductor, a high-frequency device, an electronic device, etc. with a thermosetting resin includes placing a member to be molded in a cavity between heated upper and lower molds, and filling the cavity with a heat-melted thermosetting resin. Thereafter, the thermosetting resin is pressurized and cured. A technique for molding a member to be molded with a thermosetting resin is disclosed in, for example, Patent Documents 1-3.

  Here, Patent Document 3 discloses a molding apparatus that can reduce voids formed in a thermosetting resin. A cross-sectional view of the molding apparatus of Patent Document 3 is shown in FIG. FIG. 10 is a cross-sectional view of the molding process using the molding apparatus 900 of Patent Document 3 when viewed from above. In FIG. 10A, a mold 920 having a plurality of cavities 930 is disposed on the right side of a pot 910 for supplying resin, and a void resin intake portion 940 is disposed around the pot 910. Then, as shown in FIG. 10 (b), heat containing a relatively large bubble V2 that has a high possibility of remaining as a void on the cavity 930 side of the thermosetting resin containing the bubble V1 that disappears during pressing and curing. The cured resin is caused to flow into the void resin intake portion 940 side. As a result, the formation of voids in the thermosetting resin in the cavity 930 is suppressed. When the resin is pressurized and cured, the bubbles V1 disappear, and voids formed in the thermosetting resin in the cavity 930 can be reduced as shown in FIG.

Japanese Patent Application Laid-Open No. 7-100894 Japanese Patent Laid-Open No. 9-254181 Japanese Patent Laid-Open No. 8-156034

  Although the molding apparatus 900 of Patent Document 3 can suppress the formation of voids in the thermosetting resin in the cavity 930, a void resin taking-in portion 940 is separately arranged around the pot 910, It is necessary to control the inflow direction of the cured resin to the cavity 930 side and the void resin taking-in portion 940 side, and the apparatus becomes large.

  The present invention has been made in view of the above problems, and is capable of suppressing the thermosetting resin containing bubbles that are likely to remain as voids from being pressed and cured in the cavity. It is an object of the present invention to provide an injection molding apparatus and an injection molding method having a configuration.

  In order to achieve the above object, an injection molding apparatus according to the present invention includes an upper mold and a lower mold, an inflow port through which resin flows and a discharge port through which air is discharged, and a predetermined shape formed by the upper mold and the lower mold. Measuring the amount of air discharged per unit time from the cavity and the discharge port, and outputting the measured value as a measured value, allowing the resin to flow into the cavity from the inlet, and the measured value is predetermined And a resin inflow means for causing the resin to flow at a predetermined inflow speed that is higher than the inflow speed when the measured value is smaller than the predetermined value.

  In order to achieve the above object, an injection molding method according to the present invention includes an inflow port through which resin flows in and a discharge port through which air is discharged, and resin in a cavity having a predetermined shape formed by an upper mold and a lower mold. Fill. The injection molding method allows resin to flow into the cavity from the inflow port, measures the amount of air discharged from the discharge port per unit time and outputs it as a measured value, and the measured value becomes smaller than a predetermined value. When the measured value is smaller than the predetermined value, the resin is allowed to flow at a predetermined inflow rate that is greater than the inflow rate.

  The injection molding apparatus and the injection molding method according to the present invention detect the state in which the resin starts to flow into the discharge port by measuring the discharge amount of air discharged from the discharge port per unit time, and the inflow speed of the resin Increase. By increasing the inflow rate before the resin is completely filled, the bubbles in the resin can be compressed and extinguished. In order to suppress the formation of voids in the resin, the injection molding apparatus and the injection molding method only need to add a measuring means for measuring the amount of air discharged, and thus the injection molding apparatus having a simple configuration. It is possible to suppress the thermosetting resin containing bubbles that are likely to remain as voids from being pressurized and cured in the cavity.

It is an example of sectional drawing of the injection molding apparatus 10 which concerns on the 1st Embodiment of this invention. It is an example of sectional drawing of the injection molding apparatus 100 which concerns on the 2nd Embodiment of this invention. It is an example of the upper side figure of the cavity 130 periphery of the injection molding apparatus 100 which concerns on the 2nd Embodiment of this invention. It is an example of the front view of the air vent 132c of the injection molding apparatus 100 which concerns on the 2nd Embodiment of this invention. 5A is an example of a cross-sectional view of an injection molding apparatus 100 and an injection molded product 200 in the first step of the second embodiment of the present invention, and FIG. 5B is an example of an inflow state of a thermosetting resin 240 into a cavity 130. . (A) An example of sectional drawing of injection molding device 100 and injection molded product 200 in the 2nd process of a 2nd embodiment of the present invention, and (b) An example of inflow state of thermosetting resin 240 into cavity 130. . (A) Example of sectional drawing of injection molding apparatus 100 and injection molded product 200 in 3rd process of 2nd Embodiment of this invention, (b) It is an example of the inflow state of the thermosetting resin 240 in the cavity 130. . (A) An example of sectional drawing of injection molding device 100 and injection molded product 200 in the 4th process of a 2nd embodiment of the present invention, (b) An example of inflow state of thermosetting resin 240 into cavity 130. . It is an example of transition of the injection load of the injection molding apparatus 100 which concerns on the 3rd Embodiment of this invention, the flow rate, the position of the plunger 140, and the drive speed of the plunger 140. It is sectional drawing which looked at the molding process of the molding apparatus 900 of patent document 3 from upper direction.

(First embodiment)
A first embodiment will be described. An example of a cross-sectional view of an injection molding apparatus 10 according to this embodiment is shown in FIG. In FIG. 1, the injection molding apparatus 10 according to the present embodiment includes an upper mold 20, a lower mold 30, a cavity 40, a measuring unit 50, and a resin inflow unit 60.

  The upper mold 20 and the lower mold 30 are maintained in an open state or a mold clamping state by a mold clamping mechanism (not shown). The upper mold 20 and the lower mold 30 are each provided with a recess formed in a predetermined shape, and when the upper mold 20 and the lower mold 30 are maintained in a clamped state, the upper mold 20 and the lower mold 30 have a recess. A cavity 40 is formed. The cavity 40 includes an inlet 41 through which resin flows and an outlet 42 through which air in the cavity 40 is discharged. Here, the discharge port 42 is disposed at a position farthest from the inflow port 41 in the cavity 40. A member to be molded disposed in the cavity 40 is clamped by the upper mold 20 and the lower mold 30.

  The measuring means 50 measures the amount of air discharged from the discharge port 42 of the cavity 40 per unit time. And the measurement means 50 outputs a measurement result to the resin inflow means 60 as a measured value.

  The resin inflow means 60 causes the resin to flow into the cavity 40. In the present embodiment, the resin inflow means 60 causes the resin to flow into the cavity 40 at a constant inflow speed V1. Then, the resin inflow means 60 increases the inflow speed from V1 to a predetermined V2 larger than V1 when the measured value input from the measuring means 50 becomes smaller than the predetermined value. The resin inflow means 60 can also cause the resin to flow into the cavity 40 at a predetermined pressure. Even in this case, the resin inflow unit 60 causes the resin to flow into the cavity 40 at the predetermined inflow velocity V2 when the measurement value input from the measurement unit 50 becomes smaller than the predetermined value.

  Here, the resin inflow means 60 causes the resin to flow into the cavity 40 at the inflow speed V2 when the measured value input from the measuring means 50 becomes smaller than a predetermined value near zero. That is, the resin inflow means 60 sets the inflow speed of the resin to a high speed V2 when the resin starts to flow into the discharge port 42 immediately before the cavity 40 is completely filled with the resin. By filling the resin at a high speed before the resin is completely filled in the cavity 40, the bubbles in the resin can be compressed and eliminated.

  Here, when the inflow speed is switched to the high-speed V2 in a state where only about half of the resin is filled in the cavity 40, there is a high possibility that the member to be molded is pressed by the resin and damaged. On the other hand, when the inflow speed is switched to the high speed V2 after the resin is completely filled in the discharge port 42, the resin flowing out from the discharge port 42 is solidified to prevent the air from being pushed out. I can't do it.

  The resin inflow means 60 switches the inflow speed to 0 immediately after switching the resin inflow speed to the high-speed V2. And the injection molding apparatus 10 transfers to the pressurization process from the filling process, after the inflow speed of resin switches to 0.

  As described above, the injection molding apparatus 10 according to this embodiment includes the measuring unit 50 that measures the amount of air discharged from the discharge port 42 per unit time, and the resin starts to flow into the discharge port 42. The resin inflow means 60 sets the inflow speed to a high speed V2. In this case, the bubbles in the resin are compressed, and the bubbles can be eliminated. In order to suppress the formation of voids in the resin, the injection molding apparatus 10 only needs to add a measuring means 50 for measuring the amount of air discharged, and therefore easily suppress the generation of voids. Can do.

  When the inflow speed of the resin in the filling process is set to a constant inflow speed V1, the resin inflow means 60 calculates the accumulated value of the discharged air flow from the average value of the air flow and the elapsed time, and the accumulated By starting the comparison between the measured value and the predetermined value when the value reaches the predetermined value, it is possible to efficiently detect the state in which the resin has started to flow into the discharge port 42.

(Second Embodiment)
A second embodiment will be described. The injection molding apparatus according to the present embodiment molds a bare chip with a thermosetting resin. An example of a front cross-sectional view of the injection molding apparatus and the member to be molded according to the present embodiment is shown in FIG. In the present embodiment, the bare chip 210 electrically connected to the lead frame 220 using the wire 230 is molded with a thermosetting resin 240 not shown in FIG. Although FIG. 2 shows an example in which one bare chip 210 is mounted on the lead frame 220, the number and size of the bare chips 210, the lead frame 220, and the wires 230 are not particularly limited.

  In FIG. 2, the injection molding apparatus 100 includes an upper mold 110, a lower mold 120, a cavity 130, a plunger 140, a drive source 150, a drive control unit 160, and a flow sensor 170.

  The upper mold 110 and the lower mold 120 heat and pressurize the thermosetting resin 240. The cavity 130 is a recess formed in the upper mold 110 and the lower mold 120 in a desired shape. The cavity 130 is filled with the thermosetting resin 240 and solidified into a desired shape, whereby the injection molded product 200 is molded.

  The plunger 140 is disposed in the lower mold 120, and the thermosetting resin 240 is supplied to a space formed above the plunger 140. As the plunger 140 moves upward, the thermosetting resin 240 flows into the cavity 130.

  The drive source 150 drives the plunger 140 upward at a predetermined speed. In the present embodiment, when the drive source 150 drives the plunger 140 upward at a constant drive speed V1, the thermosetting resin 240 flows into the cavity 130 by a certain amount. Furthermore, when the drive source 150 receives a control signal from the drive control unit 160, the drive source 150 drives the plunger 140 upward at a predetermined drive speed V2.

  The drive control unit 160 outputs a control signal to the drive source 150 when a later-described flow rate input from the flow sensor 170 falls below a predetermined value.

  The flow sensor 170 measures the air flow rate per unit time discharged from the cavity 130. In FIG. 2, the flow sensor 170 according to the present embodiment is disposed in close contact with the side surface of the upper mold 110. Note that the flow sensor 170 can also be disposed inside a pipe connected to the upper mold 110 and the lower mold 120.

  The measurement of the air flow rate by the flow rate sensor 170 will be described. An example of a top view around the cavity 130 is shown in FIG. In the present embodiment, the cavity 130 is formed in a square shape, and the lead frame 220 is clamped so that the bare chip 210 is positioned substantially at the center of the cavity 130. A gate 131 that is an inlet of the thermosetting resin 240 is formed at one end of the cavity 130, and air vents 132a, 132b, and 132c for discharging air are formed at the remaining three ends. In FIG. 3, the air vent 132 c faces the gate 131, and the air vent 132 c is at a position farthest from the gate 131.

  An example of a front view of the air vent 132c is shown in FIG. FIG. 4 is a view of FIG. 3 viewed from the AA side. In FIG. 4, the air vent 132c is an opening having a square cross section. In this embodiment, the opening height of the air vent 132c is set to about 10 to 20 μm. In the present embodiment, the other two air vents 132a and 132b are also formed in the same shape as the air vent 132c.

  The flow sensor 170 is disposed in close contact with the side surface of the upper mold 110, and all the air discharged from the air vents 132 a, 132 b, 132 c flows into the flow sensor 170. As the thermosetting resin 240 flows into the cavity 130 from the gate 131, the flow rate sensor 170 detects the flow rate per unit time of air discharged from the cavity 130 through the air vents 132a, 132b, and 132c (hereinafter referred to as the flow rate sensor 170). And the flow rate is measured, and the measured flow rate is output to the drive controller 160.

  The drive control unit 160 outputs a control signal to the drive source 150 when the flow rate input from the flow sensor 170 falls below F0. In the present embodiment, F0 is set to an air vent disposed at a position farthest from the gate 131 that is the inlet of the thermosetting resin 240, that is, an air discharge amount discharged per unit time from a part of the air vent 132c. Yes.

  A procedure for molding the injection molded product 200 using the injection molding apparatus 100 according to the present embodiment will be described. FIG. 5A shows an example of a cross-sectional view of the injection molding apparatus 100 and the injection molded product 200 in the first step, and FIG. 5B shows an inflow state of the thermosetting resin 240 into the cavity 130. Similarly, examples of cross-sectional views of the injection molding apparatus 100 and the injection molded product 200 in the second and third steps are shown in FIGS. 6 to 8A, and the inflow state of the thermosetting resin 240 into the cavity 130 is shown in FIGS. This is shown in FIG.

  FIG. 9 shows the transition of the injection load, the flow rate, the position of the plunger 140, and the driving speed of the plunger 140 in the first to fourth steps. Here, the injection load is the magnitude of the load applied to the thermosetting resin 240 in the cavity 130 by a resin pressing mechanism (not shown). The flow rate is a flow rate per unit time of the total air discharged from the three air vents 132a, 132b, and 132c measured by the flow sensor 170.

  When the bare chip 210, the lead frame 220, and the wire 230 are molded with the thermosetting resin 240, first, the upper mold 110 and the lower mold 120 are kept open by a mold clamping mechanism (not shown), and the upper mold 110 and the lower mold 120 are moved. It heats to about 175-180 degreeC with the heating source which is not shown in figure. In this state, the lead frame 220 is disposed on the cavity 130 formed in the lower mold 120. Furthermore, when the thermosetting resin 240 is supplied into the space above the plunger 140, since the lower mold 120 is heated to about 175 to 180 ° C., the thermosetting resin 240 starts to melt immediately after the supply.

  In this state, the lower mold 120 is raised by the mold clamping mechanism, and the lead frame 220 is clamped by the upper mold 110 and the lower mold 120 as shown in FIG. 5A (first step). The mold clamping force varies depending on the material of the lead frame 220 to be clamped, but is, for example, about 100 to 350 MPa in the case of the metal lead frame 220.

  At this time, as shown in FIG. 5B, the thermosetting resin 240 does not flow into the cavity 130. Moreover, as shown in FIG. 9, the injection load, the flow rate, the position of the plunger 140, and the driving speed of the plunger 140 are all zero.

  When the mold clamping of the lead frame 220 is completed and the thermosetting resin 240 is melted to the lowest viscosity state (after about 8 to 10 seconds), the drive source 150 starts driving the plunger 140 (second step). When the driving source 150 drives the plunger 140 upward at a constant driving speed V1, the thermosetting resin 240 starts to flow from the gate 131 into the cavity 130 as shown in FIG.

  At this time, as shown in FIG. 6B, air is discharged from the air vents 132a, 132b, 132c. The air discharged from the air vents 132a, 132b, and 132c flows out to the flow sensor 170, and the flow sensor 170 measures the flow rate and outputs it to the drive control unit 160. That is, as shown in FIG. 9, the flow rate increases from 0 to F1. In FIG. 9, the position of the plunger 140 starts to gradually increase from 0, and the driving speed of the plunger 140 increases from 0 to V1. Note that the injection load remains zero.

  Here, when the driving speed of the thermosetting resin 240 is increased, there is a high risk that the wire 230 connecting the lead frame 220 and the bare chip 210 is deformed or disconnected due to the flow resistance of the thermosetting resin 240. Accordingly, the driving source 150 drives the plunger 140 so that the thermosetting resin 240 flows at a driving speed that does not damage the wire 230. In this embodiment, the driving speed of the plunger 140 at this time is about V1 = 2 to 3 mm / sec.

  Further, when the plunger 140 is driven upward at the driving speed V1, the thermosetting resin 240 flows into the air vents 132a and 132b near the gate 131. 7A and 7B, when the thermosetting resin 240 flows into the air vents 132a and 132b, the discharge of air from the air vents 132a and 132b is stopped. By stopping the air discharge from the air vents 132a and 132b, all the air is discharged from the air vent 132c. That is, the flow rate from the air vent 132c is tripled, and the flow rate measured by the flow sensor 170 remains unchanged at F1.

  That is, in FIG. 9, the value output from the flow sensor 170 is maintained at F1. On the other hand, the driving speed of the plunger 140 decreases from V2 to V1, and the increasing rate of the position of the plunger 140 becomes small (gradient becomes gentle). Note that the injection load remains zero.

  Further, when the plunger 140 is raised at the driving speed V1, the thermosetting resin 240 flows into the air vent 132c located farthest from the gate 131. 8A and 8B, the thermosetting resin 240 flows into the final air vent 132c, so that the outflow of air from the air vent 132c decreases rapidly. Then, when the output value from the flow sensor 170 reaches a preset F0, the drive control unit 160 outputs a control signal to the drive source 150 (third step). When the control signal is input, the driving source 150 increases the driving speed of the plunger 140 to a predetermined V2. Here, F0 can be set to, for example, a predetermined value in the vicinity of 0, or an 80% value of F1 when the flow velocity trajectory is known in advance.

  The control signal is output when the thermosetting resin 240 starts to flow into the air vent 132c located farthest immediately before the cavity 130 is completely filled with the thermosetting resin 240. At this time, by increasing the driving speed of the plunger 140 to a predetermined V2, the bubbles contained in the thermosetting resin 240 are compressed and disappear.

  Here, when the driving speed of the plunger 140 is increased before the output value from the flow sensor 170 becomes F0, that is, before the wire 230 is covered with the thermosetting resin 240, the wire flow is pressed by the thermosetting resin 240. Is likely to occur. On the other hand, when the driving speed is increased after the output value from the flow sensor 170 becomes 0, the thermosetting resin 240 is completely filled in the cavity 130 at a low speed in the filling process, and the bubbles cannot be compressed completely. Since pressure is applied in the state, there is a high possibility that voids are formed in the thermosetting resin 240.

  Returning to the description of the third step. The drive source 150 drives the plunger 140 at a predetermined drive speed V2 for about several milliseconds, and then changes the drive speed of the plunger 140 from V2 to 0. When the driving speed of the plunger 140 becomes zero, the injection molding apparatus 100 starts pressurization of the thermosetting resin 240 by controlling a resin pressurization mechanism (not shown). When the injection load reaches Pw1, the filling process is switched to the pressure holding process. In this embodiment, the resin pressurizing mechanism holds the thermosetting resin 240 at an injection load Pw1 = 10 to 15 MPa. The resin pressurizing mechanism maintains the injection load Pw1 = 10 to 15 MPa until the thermosetting resin 240 is cured (for example, between about 80 seconds to 120 seconds for the curing time).

  In FIG. 9, in the third step, the flow rate becomes 0 after passing from F1 to F0. Furthermore, after the driving speed of the plunger 140 is increased from V1 to V2, it is changed to zero. As a result, the position of the plunger 140 is rapidly raised and then held at the highest position Ps1. The injection load starts increasing from 0 toward Pw1 when the driving speed becomes zero.

  Then, after the thermosetting resin 240 is cured, the injection load is released, the mold clamping load is released, and the plunger 140 is lowered to the initial position (fourth step). That is, in FIG. 9, the injection load decreases from Pw1 toward 0. Further, by driving the plunger 140 downward, the plunger 140 is lowered from the position of Ps1 to the initial position. Thereafter, the lower mold 120 is lowered to take out the injection molded product 200 formed by molding the bare chip 210, the lead frame 220 and the wire 230 with the thermosetting resin 240, and return the plunger 140 to the 0 point.

  As described above, the injection molding apparatus 100 according to the present embodiment increases the driving speed of the plunger 140 to a predetermined V2 when the output value from the flow sensor 170 becomes F0. The injection molding apparatus 100 detects the state in which the thermosetting resin 240 starts to flow into the air vent 132c at the most distant position immediately before the thermosetting resin 240 is completely filled in the cavity 130, and drives the plunger 140. By increasing the speed to a predetermined V2, the bubbles contained in the thermosetting resin 240 can be compressed and extinguished. Therefore, the injection molding apparatus 100 according to the present embodiment can easily suppress the thermosetting resin 240 containing bubbles that are likely to remain as voids from being pressed and cured in the cavity 130.

  Further, the time required for the molding process can be shortened by changing the driving speed to the high-speed V2 when the cavity 130 is almost filled with the thermosetting resin 240 and the probability of occurrence of wire flow is low. In addition, in order to detect the flow rate with high accuracy, deaeration molding can be performed by adding a vacuum source.

DESCRIPTION OF SYMBOLS 10 Injection molding apparatus 20 Upper mold | type 30 Lower mold | type 40 Cavity 50 Measuring means 60 Resin inflow means 100 Injection molding apparatus 110 Upper mold | type 120 Lower mold | type 130 Cavity 140 Plunger 150 Drive source 160 Drive control part 170 Flow sensor 200 Injection molded product 210 Bare chip 220 Lead frame 230 Wire 240 Thermosetting resin

Claims (7)

With upper and lower molds,
A cavity having a predetermined shape formed by the upper mold and the lower mold, including an inflow port through which resin flows in and an exhaust port through which air is discharged;
Measuring means for measuring the amount of air discharged from the discharge port per unit time and outputting as a measurement value;
When resin flows into the cavity from the inflow port and the measured value becomes smaller than a predetermined value, the resin flows into the cavity at a predetermined flow rate greater than the flow rate when the measured value becomes smaller than the predetermined value. Resin inflow means for inflow at a speed;
An injection molding apparatus comprising: The injection molding apparatus according to claim 1, wherein the predetermined value is an air discharge amount discharged per unit time from a part of the discharge port. 3. The injection molding apparatus according to claim 1, wherein the resin inflow unit increases the inflow rate to the predetermined inflow rate, and then changes to 0. 4. A pressurizing unit that pressurizes the resin in the cavity with a predetermined stress;
The injection molding apparatus according to claim 3, wherein the pressurizing unit starts the pressurization when the inflow speed is changed to zero. A driving means for driving the resin inflow means;
The drive means drives the resin inflow means at a constant drive speed, and increases the drive speed to a predetermined drive speed when the measured value becomes smaller than a predetermined value. An injection molding apparatus according to claim 1. The cavity comprises a plurality of outlets;
The measuring means measures a total discharge amount per unit time of air discharged from all the plurality of discharge ports,
The injection molding according to any one of claims 2 to 5, wherein the predetermined value is an air discharge amount discharged per unit time from a part of the discharge port disposed at a position farthest from the inflow port. apparatus. An injection molding method for filling a cavity, which is a space having a predetermined shape formed by an upper mold and a lower mold, with an inlet through which resin flows in and an outlet through which air is discharged,
Let the resin flow into the cavity from the inlet,
Measure the amount of air discharged per unit time from the outlet and output it as a measured value.
An injection molding method in which when the measured value becomes smaller than a predetermined value, the resin is caused to flow at a predetermined inflow speed that is higher than an inflow speed when the measured value becomes smaller than the predetermined value.

Images