JP4467207B2 - Resin sealing method and substrate clamping mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, when a chip-like component such as a semiconductor chip is resin-sealed to a wiring member (hereinafter referred to as a board) made of a lead frame, a printed board, or the like, the board is clamped with an appropriate pressure and resin-sealed. The present invention relates to a resin sealing method and a substrate clamping mechanism.
[0002]
[Prior art]
Conventionally, when a molten resin is injected into a cavity of a mold of a resin sealing device and a chip-like component accommodated in the cavity is resin-sealed, the following has been performed. First, a substrate on which chip-shaped components are mounted is placed on the lower mold side stage, and the upper mold and the lower mold are clamped. Next, molten resin is poured into a cavity provided in the upper mold and cured. Next, the mold is opened, and the package whose resin sealing is completed is taken out.
Here, if the molten resin leaks between the molds, a resin flash occurs. In order to prevent this, in the conventional clamping mechanism, a spring is provided between the lower mold body and the stage, and the substrate is clamped by the pressure of the spring.
[0003]
[Problems to be solved by the invention]
However, according to the above conventional resin sealing method, when the pressure (clamping pressure) at the time of clamping the substrate is smaller than the pressure (resin pressure) of the molten resin injected into the cavity, the molten resin leaks out. Resin flash is generated, and it is necessary to make the clamp pressure larger than the resin pressure in order to prevent this. The clamp pressure varies depending on the material and size of the substrate, the resin pressure, and the like, and is set to, for example, about 5 to 12 kg / mm ² .
Here, there are the following problems. The first problem is that when the clamping pressure is too large, cracks or deformations occur in the substrate. In particular, in recent years, there is a strong demand for thinning the package, and the substrate tends to be thinned, so that the necessity of maintaining a proper clamping pressure is increasing. The second problem is that it is necessary to use a spring having a large spring constant because the clamp pressure must be larger than the resin pressure. For this reason, when the substrate thickness varies, the clamp pressure is kept constant. It becomes difficult. Therefore, resin burrs and substrate cracks and deformations are likely to occur.
[0004]
The present invention has been made in order to solve the above-mentioned problems, and when resin-sealing, a resin that clamps the substrate with an appropriate pressure that does not cause cracks or deformation in the substrate and prevents resin flash An object is to provide a sealing method and a substrate clamping mechanism.
[0005]
[Means for Solving the Problems]
In order to solve the above technical problem, a resin sealing method according to the present invention is a resin sealing method in which a chip-shaped component is resin-sealed using a mold set provided with opposing cavities. Placing the substrate on which the chip-like component is mounted on a stage provided on one mold side of the mold set; clamping the mold by clamping the mold set; and A step of pushing the stage by applying a clamping pressure for clamping the substrate to an elastic member provided in contact with the stage through the stage, and a contact of a rigid member provided in one mold to the stage a step of supporting the tucked was stage is added together with the molten resin is injected into the cavity, the rigid member through the stage resin pressure due to injection of the molten resin Engineering If, curing the molten resin, the mold set is opened mold and a step of taking out a package which chip-like components are sealed with a resin, the stage has a tapered surface on the side facing the rigid member, The rigid member has a tapered surface facing the tapered surface of the stage, and in the step of supporting the stage, the rigid member is advanced to support the pressed stage by bringing the tapered surfaces into contact with each other. And
[0006]
According to this, when the mold is clamped, the clamping pressure for the substrate is applied to the elastic member via the stage, so that only the clamping pressure determined by the elastic member is applied to the substrate. Therefore, by using an appropriate elastic member, the substrate can always be clamped with an optimum clamping pressure. Further, since the resin pressure is applied to the rigid member when the molten resin is injected into the cavity, no gap is generated between the clamped substrate and the mold set. Therefore, it is possible to suppress the occurrence of resin flash due to leakage of the molten resin. Even when the thicknesses of the substrates are different, the stage can be supported by advancing a rigid member having a tapered surface and bringing the tapered surface into contact with the tapered surface of the stage. Therefore, even for substrates having different thicknesses, no gap is generated between the clamped substrate and the mold set, so that the occurrence of resin flash due to leakage of the molten resin can be suppressed.
[0007]
[0008]
[0009]
In order to solve the above technical problem, the substrate clamping mechanism according to the present invention is:
A substrate clamping mechanism for use in resin-sealing chip-shaped components on a substrate, wherein one of the mold sets provided opposite to each other and one of the mold sets The other mold provided opposite to the mold, the stage provided on one mold and on which the substrate is placed, and the surface of the stage on which the substrate is placed in one mold. An elastic member provided in contact with the opposite surface, and a rigid member provided so that the mold can be separated and contacted with the opposite surface of the stage in one mold. in a state where the mold and the other mold is clamping, the substrate stage is pushed by Rukoto applied to the elastic member via the clamping pressure stage to be clamped, and the rigid member to the stage those contact possible der is, the opposite side of the stage Consists tapered surface, the rigid member has a tapered surface facing the tapered surface of the stage, by tapered faces abut one another rigid member is advanced, wherein the tucked was stage is supported .
[0010]
According to this, when the mold is clamped, the clamping pressure on the substrate is applied to the elastic member via the stage, so that only the clamping pressure determined by the elastic member is applied to the substrate. Accordingly, by using an appropriate elastic member, the substrate is always clamped with an optimum clamping pressure. In addition, since the stage and the rigid member can come into contact with each other when the mold is clamped, the resin pressure by the resin sealing can be applied to the rigid member through the stage. As a result, no gap is generated between the clamped substrate and the mold set. Therefore, the occurrence of resin flash due to leakage of the molten resin is suppressed. Even if the thicknesses of the substrates are different, the rigid member having a tapered surface advances and the tapered surface comes into contact with the tapered surface of the stage, so that the stage is supported by the tapered member. Therefore, even for substrates having different thicknesses, no gap is generated between the clamped substrate and the mold set, so that occurrence of resin flash due to leakage of molten resin is suppressed.
[0011]
[0012]
[0013]
DETAILED DESCRIPTION OF THE INVENTION
A resin sealing method and a substrate clamping mechanism according to the present invention will be described with reference to FIGS. FIGS. 1A and 1B show the state when the upper mold is in contact with the substrate in the resin sealing method according to the present invention, and immediately before the movable taper member for advancing and retracting moves forward after the mold is clamped. It is a fragmentary sectional view showing each of these states.
[0014]
In FIG. 1, reference numeral 1 denotes a lower mold of the resin sealing device, and 2 denotes an upper mold provided facing the lower mold 1. Reference numeral 3 denotes a mold set including a lower mold 1 and an upper mold 2. The mold set 3 is preheated to about 180 ° C. by a heater (not shown). Reference numeral 4 denotes a recess provided in the lower mold 1. Reference numeral 5 denotes a rigid member provided so as to be movable in the horizontal direction (left-right direction in the drawing) in the concave portion 4, and is a movable taper member for advancement and retraction having an upper surface tapered. 6, the upper surface is a flat surface, and the lower surface is a tapered surface, and the lower surface is provided to face the upper surface of the movable taper member 5, that is, the tapered surfaces are provided to face each other. It is a taper member for a stage. Reference numeral 7 denotes a through hole provided so as to overlap the movable taper member 5 and the stage taper member 6 at the initial position of the movable taper member 5. Reference numeral 8 denotes a compression spring made of, for example, a coil spring, provided as an elastic member in the through hole 7. 9, the stage taper member 6 is fixed in a state where the upper surface of the stage taper member 6 is in contact with the lower surface thereof, and the substrate mounting table supported by the compression spring 8 at the initial position of the movable taper member 5. It is. Reference numeral 10 denotes a stage constituted by the stage taper member 6 and the substrate mounting table 9. Reference numeral 11 denotes a substrate placed on the stage 10, and 12 denotes a semiconductor chip mounted on the substrate 11.
[0015]
Here, the stage 10 is supported by the compression spring 8 as follows in a state where the mold surface of the upper mold 2 is in contact with the upper surface of the substrate 11. First, the stage 10 is supported so that the upper surface of the substrate 11 protrudes from the mold surface of the lower mold 1 when the mold surface of the upper mold 2 contacts the upper surface of the substrate 11. Secondly, as shown in FIG. 1B, the stage 10 is such that the lower surface of the stage 10 is separated from the upper surface of the movable taper member 5 when the mold set 3 is clamped, that is, a tapered surface. The two are supported so as to be separated from each other.
[0016]
Reference numeral 13 denotes a space provided in the upper mold 2, which is a cavity in which the semiconductor chip 12 is accommodated and molten resin is injected. Reference numeral 14 denotes a resin passage for the molten resin, which communicates with a cal (not shown) that is a supply source of the molten resin.
[0017]
Reference numeral 15 denotes a base in which the lower mold 1 is accommodated. Reference numeral 16 denotes an air cylinder attached to the side surface of the base 15, and 17 denotes a rod of the air cylinder 16. Reference numeral 18 denotes a space provided on the side wall of the base 15. Reference numeral 19 denotes a protruding plate provided in the space 18 and protruding by the rod 17. Reference numeral 20 denotes a compression spring provided in the space 18 for returning the protruding plate 19 to the initial position when the rod 17 is not protruding. Reference numeral 21 denotes an ejector bar which is formed integrally with the ejector plate 19 and whose tip is fixed to the movable taper member 5.
[0018]
1 will be described with reference to FIGS. 1 and 2. FIG. 2A and 2B are partial cross-sectional views showing a state where the rigid member supports the stage and a state where molten resin is injected into the cavity, respectively, in the resin sealing method according to the present invention.
[0019]
First, as shown in FIG. 1A, in a state where the rod 17 does not protrude, that is, in a state where the movable taper member 5 is in the initial position, the upper die 2 is brought into contact with the upper surface of the substrate 11. Lower. As described above, at this time, the stage 10 is supported by the compression spring 8 so that the upper surface of the substrate 11 protrudes from the mold surface of the lower mold 1.
[0020]
Next, as shown in FIG. 1B, the upper mold 2 is continuously lowered until the mold surfaces of the upper mold 2 and the lower mold 1 come into contact with each other. Thereby, the mold clamping by the mold set 3 is completed. As described above, at this time, the stage 10 is supported by the compression spring 8 such that the lower surface, that is, the tapered surface is separated from the tapered surface of the movable taper member 5, that is, the tapered surfaces are separated from each other. Has been.
[0021]
Next, as shown in FIG. 1B as well, the air cylinder 16 is operated, and the protrusion rod 21 is protruded by the rod 17. Then, as shown in FIG. 2A, the movable taper member 5 is advanced to the right side in the drawing until it abuts against the taper surface of the stage 10. Thereby, the taper surface of the movable taper member 5 and the taper surface of the stage 10 are brought into contact with each other. In this state, the clamping pressure by the mold set 3 is applied to the movable taper member 5 that is a rigid member via the stage 10, and the clamping pressure by the compression spring 8 is applied to the substrate 11. It will be. In the present invention, for example, the compression spring 8 can be selected so that the clamp pressure is about 1 to 3 kg / mm ² .
In addition, since the air cylinder 16 is used, even if the substrate 11 has a thickness variation, the variation can be absorbed by the pressure of the air that is the working fluid.
[0022]
Next, as shown in FIG. 2B, the molten resin 22 is pressurized and injected into the cavity 13 using a plunger (not shown). In this state, the resin pressure by the molten resin 22 is applied to the movable taper member 5 that is a rigid member through the substrate 11, the semiconductor chip 12, and the stage 10 in order.
[0023]
Next, after the molten resin 22 is cured to form a cured resin on the substrate 11, the mold set 3 is opened. In this state, the air cylinder 16 is operated to return the rod 17 to the initial position. As a result, the compression spring 20 pushes back the protruding plate 19, so that the protruding rod 21 and the movable taper member 5 are in the initial position with the rod 17 and the protruding plate 19 being separated as shown in FIG. Return. Therefore, when the mold set 3 is opened, the air cylinder 16 and the mold set 3 are thermally shut off.
[0024]
Next, the substrate 11 is protruded by ejector pins (not shown). As a result, the substrate 11 on which the cured resin is formed, that is, the package in which the resin sealing is completed is taken out.
[0025]
Here, the first feature of the present invention is that, as shown in FIG. 1B, the clamping pressure applied to the substrate 11 when the mold is clamped is determined only by the compression spring 8. Therefore, if the spring constant of the compression spring 8 is appropriately determined, the substrate 11 is always clamped with the maximum clamping pressure in a range where cracks, deformation, and the like do not occur. For example, the substrate 11 is sufficiently low compared to the conventional clamping pressure 5~12kg / mm ^2, is clamped by the clamping pressure 1 to 3 kg / mm ² approximately.
Further, as shown in FIG. 2A, the second feature is that the stage 10 is supported by the movable taper member 5 which is a rigid member after the mold clamping and before the molten resin 22 is injected into the cavity 13. It is to be done. Thereby, the resin pressure when the molten resin 22 is injected into the cavity 13 is applied to the movable taper member 5. Accordingly, no gap is generated between the upper mold 2 and the substrate 11 even when the resin pressure is applied, so that the occurrence of resin flash due to leakage of the molten resin 22 is suppressed.
The third feature is that, as shown in FIG. 1 (A), the air cylinder 16 is less likely to receive heat conduction from the mold set 3 when the mold set 3 is opened. . Therefore, the influence of heat that the air cylinder 16 receives from the mold set 3 is reduced.
[0026]
As described above, according to the present invention, by setting the spring constant of the compression spring 8 appropriately, setting is made so that the substrate 11 is clamped with an appropriate clamping pressure that does not cause cracks or deformation in the substrate 11. can do. Further, even if a resin pressure is applied when the molten resin 22 is injected, no gap is generated between the upper mold 2 and the substrate 11, so that the occurrence of resin flash due to the leakage of the molten resin 22 is suppressed. Moreover, since the influence of the heat which the air cylinder 16 receives from the metal mold | die set 3 is reduced, the malfunctioning of the air cylinder 16 can be prevented.
[0027]
As a modification of the present invention, a resin sealing method and a substrate clamping mechanism that are used by combining a spacer and a taper member and exchanging the spacer will be described with reference to FIG. FIGS. 3A and 3B are partial cross-sectional views respectively showing a state before and after replacement in a case where the spacer is replaced in order to cope with a substrate having a small thickness in the substrate clamping mechanism according to this modification. FIG.
[0028]
In FIGS. 3A and 3B, reference numerals 23 and 24 denote spacers made of a plate member of the same material having rigidity, and are respectively placed on the stage 10. The spacers 23 and 24 each have a predetermined plate thickness, and the plate thickness of the spacer 24 is set to be larger than the plate thickness of the spacer 23. Reference numeral 25 denotes a substrate having a standard for a substrate thickness smaller than that of the substrate 11 in FIGS.
[0029]
This modification is applied when there is a possibility that a resin flash may occur according to the resin sealing method of FIGS. First, as shown in FIG. 3A, a spacer 23 having a predetermined thickness is placed on the stage 10.
[0030]
Next, after placing the substrate 25 on the spacer 23, the mold set 3 is clamped. In this case, since the substrate thickness of the substrate 25 is small, the distance between the lower surface of the stage 10 and the upper surface of the movable taper member 5 is increased when the mold is clamped. Depending on the thickness of the substrate and the thickness of the spacer 23, the upper surface of the movable taper member 5 may not be brought into contact with the lower surface of the stage 10 only by moving the movable taper member 5 to the right. When resin sealing is performed in this state, the compression spring 8 is compressed by resin pressure. Therefore, there is a possibility that a resin flash may occur due to a gap between the upper mold 2 and the substrate 25.
[0031]
Next, as shown in FIG. 3B, after the mold is opened and the substrate 25 is taken out, a spacer 24 having a large substrate thickness is placed on the stage 10 instead of the spacer 23. Thereafter, in the same manner as described above, after the substrate 25 is placed on the spacer 24, the mold set 3 is clamped. In this case, if the thickness of the spacer 24 is appropriate, the stage 10 is sufficiently lowered when the mold is clamped. As a result, the distance between the lower surface of the stage 10 and the upper surface of the movable taper member 5 becomes smaller than in the case of FIG. 3A, so that the upper surface of the movable taper member 5 is moved to the stage by the movement of the movable taper member 5 to the right side. 10 can be brought into contact with the lower surface.
[0032]
Here, in practice, it is preferable to check in advance for substrates having various substrate thicknesses whether or not the upper surface of the movable taper member 5 can be brought into contact with the lower surface of the stage 10 by horizontal movement. . And when using the board | substrate which has a certain board | substrate thickness standard, what is necessary is just to select and use the spacer of the thickness corresponding to the board | substrate thickness.
[0033]
Since the thickness of the substrate 25 is large, the upper surface of the movable taper member 5 and the lower surface of the stage 10 may come into contact with each other before the mold set 3 is clamped. In this case, a spacer having a smaller thickness may be used in place of the spacer 23.
[0034]
As described above, according to this modification, when the mold set 3 is clamped, the range of the thickness difference of the substrate 25 that can bring the upper surface of the movable taper member 5 into contact with the lower surface of the stage 10 is reduced. Can be extended. Therefore, it is possible to set the substrate 25 to be clamped at an appropriate clamping pressure by exchanging spacers having different thicknesses for a plurality of types of substrates 25 having greatly different thickness standards. The occurrence of resin flash can be suppressed.
[0035]
In the above description, the movable taper member 5 and the stage taper member 6 are provided. Instead of this, a rotating cam or a surface cam, which is a rigid member, may be provided below the substrate mounting table 9, and an elastic member may be provided around the cam so as to keep the substrate mounting table 9 horizontal. Also with this configuration, the clamping pressure on the substrate can be made appropriate, and the occurrence of resin flash can be suppressed.
[0036]
Further, although the coil spring is used as the compression spring 8, the present invention is not limited to this, and a spring such as a leaf spring or a disc spring or a polymer material having elasticity may be used.
[0037]
Further, when the lower mold 1 and the upper mold 2 are combined, the present invention is applied. The present invention can be applied not only to such a combination but also to clamp substrates placed on molds facing each other in the horizontal direction.
[0038]
In addition to the air cylinder, for example, a hydraulic cylinder or the like may be used.
[0039]
Further, a sensor can be used in combination with a mechanism that can arbitrarily set the protruding amount, for example, a mechanism that combines a stepping motor, a servo motor, and the like with a ball screw. In this case, a sensor is provided on the lower surface of the stage 10 or the upper surface of the movable taper member 5. This sensor detects that the lower surface of the stage 10 and the upper surface of the movable taper member 5 are in contact with each other, or detects that the pressure between them has reached a predetermined pressure, and transmits a signal to the controller. To do. Then, the controller transmits a signal for stopping the protrusion of the movable taper member 5 to the servo motor or the like. Thereby, the movable taper member 5 can be advanced to an optimal position.
[0040]
Further, the case where a substrate, that is, a lead frame, a printed circuit board or the like is clamped has been described. The present invention is not limited to this and can be applied to other wiring members such as a flexible substrate and a ceramic substrate.
[0041]
Further, the present invention is not limited to the above-described embodiments, and can be arbitrarily changed and selected as necessary within a range not departing from the gist of the present invention. .
[0042]
【The invention's effect】
According to the present invention, even when the substrate has a variation in thickness, the elastic member is appropriately determined so that the substrate is clamped with an appropriate clamping pressure that does not cause cracks or deformation in the substrate. can do. Further, since the resin pressure of the molten resin is applied to the rigid member, it is possible to suppress the occurrence of resin flash due to the molten resin leaking between the other mold and the substrate.
Therefore, the present invention provides a resin sealing method and a substrate clamping mechanism for clamping a substrate with an appropriate pressure that does not cause cracks or deformation in the substrate when resin sealing is performed, and preventing resin flash. It has excellent practical effects.
[Brief description of the drawings]
FIGS. 1A and 1B show a state when an upper mold contacts a substrate and a movable taper member for advancing and retreating after the mold is clamped in a resin sealing method according to the present invention. It is a fragmentary sectional view showing a state just before carrying out, respectively.
FIGS. 2A and 2B are partial cross-sectional views showing a state where a rigid member supports a stage and a state where molten resin is injected into a cavity, respectively, in the resin sealing method according to the present invention. .
FIGS. 3A and 3B show a state before and after replacement in a case where a spacer is replaced to cope with a substrate having a small thickness in a modified example of the substrate clamping mechanism according to the present invention. It is a fragmentary sectional view showing each.
[Explanation of symbols]
1 Lower mold (one mold)
2 Upper mold (the other mold)
3 Mold set 4 Recess 5 Movable taper member (rigid member)
6 Tapered member for stage 7 Through hole 8 Compression spring (elastic member)
9 Substrate mounting table 10 Stage 11, 25 Substrate 12 Semiconductor chip (chip-shaped component)
13 Cavity 14 Resin passage 15 Base 16 Air cylinder 17 Rod 18 Space 19 Extrusion plate 20 Compression spring 21 Extrusion rod 22 Molten resin 23, 24 Spacer

Claims (2)

A resin sealing method in which a chip-shaped component is resin-sealed using a mold set provided opposite to each other with a cavity,
Placing the substrate on which the chip-like component is mounted on a stage provided on one mold side of the mold set;
Clamping the substrate by clamping the mold set, and pressing the stage by applying a clamping pressure for clamping the substrate to an elastic member provided in contact with the stage via the stage When,
Supporting the pushed-in stage by bringing a rigid member provided in the one mold into contact with the stage;
Injecting molten resin into the cavity, and applying a resin pressure when injecting the molten resin to the rigid member through the stage;
Curing the molten resin;
A step of opening the mold set and taking out the package in which the chip-shaped component is sealed with a resin ,
The stage has a tapered surface on the side facing the rigid member,
The rigid member has a tapered surface facing the tapered surface of the stage;
In the step of supporting the stage, the rigid member is advanced to bring the tapered surfaces into contact with each other, thereby supporting the pushed-in stage . A substrate clamping mechanism used when resin-sealing chip-like components on a substrate,
One of the mold sets provided opposite to each other;
The other mold provided opposite to the one mold in the mold set;
A stage provided on the one mold and on which a substrate is placed;
In the one mold, an elastic member provided in contact with a surface opposite to a surface on which the substrate is placed among surfaces of the stage;
A rigid member provided so that separation and contact with the opposite surface of the stage in the one mold is possible;
In a state in which the one mold and said other mold is mold clamping, the stage by Rukoto clamping pressure which the substrate is clamped is applied to the elastic member through the stage it is pushed, and , Ri can contact der said rigid member to said stage,
The opposite surface of the stage is a tapered surface,
The rigid member has a tapered surface facing the tapered surface of the stage;
The substrate clamping mechanism, wherein the rigid member is advanced and the tapered surfaces are brought into contact with each other to support the pushed-in stage .

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