JP3672209B2 - Molding mold by movable cavity method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold for molding using a movable cavity method used when molding a semiconductor package or the like.
[0002]
[Prior art]
Conventionally, a general semiconductor package is manufactured by bonding a semiconductor element, such as a semiconductor integrated circuit (IC) chip, to a lead frame and resin molding. Members such as lead frames, substrates, and tapes (hereinafter referred to as “workpieces”) to be molded have variations in thickness. Therefore, when a plurality of workpieces are set and pressed simultaneously on the mold, a difference in the pressing state naturally occurs depending on the plate thickness of each workpiece. And since it is obstructed by a thick workpiece, an unnecessary gap is apt to be generated between the cavity block and the workpiece in the thin workpiece. Therefore, resin burrs are easily generated, and a good molded state cannot be secured.
[0003]
Therefore, in order to deal with variations in the plate thickness of the workpiece, the present applicant previously presented a molding die 1 by a movable cavity method as shown in Japanese Patent Application No. 51-6905 as shown in FIGS. The mold 1 is a mold for molding a package on a lead frame. The upper and lower chase blocks 2 and 3 are disposed on the mold base, the upper chase block 2 is provided with the upper center block 4 at the lower center portion, and the upper cavity blocks 5 (5a and 5b) on the left and right sides thereof. The lower center block 6 is disposed at the upper center portion corresponding to the lower chase block 3, and the lower cavity blocks 7 (7a, 7b) are disposed on the left and right sides thereof. Further, a pressing force application mechanism 8 {8a (8a1, 8a2, 8a3), 8b} is provided for the upper cavity block 5 by applying a pressing force to them.
[0004]
Each of these pressing force application mechanisms 8 is provided with, for example, three pin holes in the upper chase block 2 so as to correspond to predetermined positions of the upper cavity blocks 5, and faces the upper cavity block 5 of each pin hole. The diameter of the portion is increased to form a spring chamber 11, and six disc springs 12 are stacked in the spring chamber 11, and the upper cavity block 5 passes through the upper chase block 2 and the disc spring 12. The pin 13 is provided so as to be fixed to the head. Therefore, the upper chase block 2 is provided with the gaps 14 (14a, 14b) to support the upper cavity blocks 5 so as to be movable up and down, and the laminated bodies of the disc springs 12 can hold the gaps 14 respectively.
[0005]
When the lead frame 15a is thick and the lead frame 15b is thin, for example, depending on the plate thickness of the lead frame 15 (15a, 15b) set in the molding die, each disc spring is applied to the thick lead frame 15a. The amount of contraction of 12 and the amount of movement of the upper cavity block 5a increase, and the interval 14a closes. On the other hand, for the thin lead frame 15b, the amount of contraction of each disc spring 12 and the amount of the upper cavity block 5b The amount of movement decreases and the interval 14b opens. Accordingly, each lead frame 15 is pressed against the upper cavity block 5 in accordance with the thickness of the lead frame 15, so that unnecessary gaps are not generated, and resin burrs are not generated. Reference numeral 16 denotes a cavity of the upper cavity block 5, and reference numeral 17 denotes a corresponding cavity of the lower cavity block 7, which corresponds to a package forming location.
[0006]
[Problems to be solved by the invention]
However, when the upper chase block 2 is provided with a spring chamber 11 for accommodating a spring such as a disc spring 12 corresponding to each upper cavity block 5 provided therein, and each pressing force applying mechanism 8 is formed, each cavity block is formed. 5 and 7 are provided with ejector pins (not shown) for projecting the molded product, respectively, and therefore the size and position of the spring such as the disc spring 12 are restricted by the ejector pins. Moreover, if the springs such as the disc springs 12 are made small, it is difficult to produce the necessary pressing force even if they are used in large numbers.
[0007]
A BGA type semiconductor package or the like usually uses a plastic substrate having a multi-layer structure, but unlike a metal plate such as a lead frame, such a plastic substrate varies in thickness depending on the location. Therefore, even if a pressing force application mechanism is provided at a plurality of locations of one cavity block, the pressing force mainly acts on the thick portion of the substrate and does not work much on the thin portion. And it is easy to make a resin burr | flash on the parting surface of the package formed in the thin part vicinity of a plastic substrate. Therefore, the pressing force is increased to prevent the generation of resin burrs, but if it is too strong, the substrate will be destroyed. Moreover, in order to adjust the pressing force of the disc spring laminated body, it is necessary to remove all the disc springs and interpose a washer or a spacer between the disc springs. For this reason, the burden of pressure adjustment is large.
[0008]
The present invention has been made paying attention to such conventional problems, and it is easy to select a pressing position to be applied to the cavity block, to adjust the size of the pressing force, and to obtain a large pressing force. It is an object of the present invention to provide a mold for molding using a movable cavity system in which resin burrs are hardly generated.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the mold according to the movable cavity method according to the present invention, a chase block having a cavity block is installed on the mold base, and a pressing force is applied by applying a pressing force to the cavity block. Provide a mechanism. Then, by dividing the cavity block corresponding to one of the work described above a plurality, for each divided block having the cavity, there by adding pressing force respectively installed a pressing force applying mechanism for moving, each As a pressing force application mechanism, a pressing force source that applies a pressing force to the rear end of the pillar by inserting a pillar that transmits the pressing force into a corresponding hole provided in the chase block, bringing the tip of the pillar into contact with the corresponding divided block Is provided on the mold base.
[0010]
In addition, a chase block having a cavity block is installed on the mold base, and a pressing force application mechanism is provided to move the cavity block by applying a pressing force. The chase block includes only the cavity block , and the cavity block corresponding to the one workpiece is integrally formed including a runner and a cull respectively connected to the plurality of cavities, and has the cavity of the cavity block. Each part is provided with a pressing force application mechanism that moves it by applying a pressing force to each part. As each pressing force application mechanism, a pillar that transmits the pressing force is inserted into a corresponding hole provided in the chase block. One end of the pillar is brought into contact with the corresponding portion , and a pressing force source for applying a pressing force to the other end of the pillar is provided in the mold base.
In addition, it is preferable to divide each portion having the cavity of the cavity block and to install a pressing force application mechanism for moving each of the divided blocks by applying a pressing force thereto.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view of a main part viewed from the front side of a mold using a movable cavity system to which the present invention is applied. The mold 18 is a mold that molds and fixes a package on a lead frame, and is composed of molds 19 and 20 that are arranged on the upper and lower sides. The upper die 19 is provided with a chase block 22 at the lower center portion of the die base 21, a center block 23 is disposed at the lower center portion of the chase block 22, and cavity blocks 24 ( 24a, 24b) are arranged and provided respectively. Usually, two cavity blocks are provided in one chase block.
[0012]
A chase block 26 is installed at the upper center of the mold base 25 of the lower mold 20, a center block 27 is arranged at the upper center of the chase block 26, and cavity blocks 28 (28a, 28b) on the left and right sides thereof. And arrange each. Then, the upper and lower cavity blocks 24a and 28a are paired, and the upper and lower cavity blocks 24b and 28b are paired to form a package forming cavity 29 (29a and 29b), respectively. Reference numeral 30 denotes an ejector plate that projects an ejector pin (not shown) upward.
[0013]
The upper mold 19 is further provided with a pressing force application mechanism 31 (31a, 31b) that applies a pressing force to each upper cavity block 24 to move it. For each cavity block 24, one or more pressing force application mechanisms 31, for example, three sets are installed. At that time, three through-holes that face the upper surface of each upper cavity block 24 are distributed and provided in the upper chase block 22, and pillars 32 (32 a and 32 b) are inserted into the respective holes to stand upright. . These pillars 32 are push-down columnar members, and their tips ride on and contact the upper surface of the upper cavity block 24. In addition, 33 is an ejector plate which protrudes an ejector pin (not shown) toward the downward direction.
[0014]
In addition, in order to receive the rear ends of the pillars 32, square plate-like pillar receivers 34 (34a, 34b) that are placed on the pillars 32 are installed at the center of the upper mold base 21, respectively. Then, in order to transmit the pressing force to each pillar receiver 34, one or more, for example, two pressing force transmitting members 35 that ride on each pillar receiver 34 are installed. Further, as a pressing force source for applying a pressing force to each pressing force transmitting member 35 {35a (35a1, 35a2), 35b (35b1, 35b2)}, a compression coil spring 36 {36a ( 36a1, 36a2), 36b (36b1, 36b2)}, respectively.
[0015]
At this time, the upper end portion of each compression coil spring 36 is received by a disk-shaped member 38 with a screw 37, and the lower end portion is brought into contact with the disk-shaped head portion 39 of the pressing force transmitting member 35. Then, by rotating the screw 37, the disk-shaped member 38 can be moved up and down to become a spring force adjusting member. The foot portion 40 of the pressing force transmission member 35 is formed in a columnar shape.
[0016]
In this way, the pillars 32 are inserted one by one through the six holes provided in the upper chase block 22, and the tips of the pillars 32 are respectively brought into contact with the corresponding upper cavity blocks 24, Each pillar receiver 34 that receives the rear end of each of the pillars 32 is provided at the center of the upper die base 21 and two pressing force transmission members 35 that transmit the pressing force to each of the pillar receivers 34 are provided. When one end of each of them is brought into contact with each other and six compression coil springs 36 for applying a pressing force to each of the pressing force transmitting members 35 are provided at the upper central portion of the upper mold base 21, respectively, a molding die is formed. Six sets of pressing force application mechanisms 31 can be arranged on the 18. Each cavity block 24, each pillar receiver 34, each pressing force transmission member 35, etc. must naturally be movable in the vertical direction, so that a small moving interval is formed in the vicinity thereof. deep.
[0017]
In addition, when each pressing force application mechanism 31 is configured in this way, it is only necessary to stand up by inserting each pillar 32 in the upper chase block 22, so that the upper chase block 22 is inserted downward. The position of each pillar 32 is not easily restricted by each ejector pin that protrudes. Therefore, it is possible to select a pressing position to be applied to each upper cavity block 24, and it is easy to distribute and apply the pressing force evenly to each upper surface thereof. Further, each pillar 32 can be replaced with a plurality of pillars having a reduced diameter.
[0018]
In addition, since the other pillar receivers 34, the pressing force transmission member 35, the compression coil spring 36 serving as the pressing force source, and the like are installed on the upper mold base 21, a large compression coil spring 36 is adopted, or the compression coil spring 36 The number can be increased. Therefore, the degree of freedom of the pressing force application mechanism 31 is increased, the amount of pressing force applied to each pillar 32 can be easily adjusted, and a large pressing force can be easily obtained. In addition, a hydraulic cylinder or the like may be used as a pressing force source, and in this case, the piston rod serves as a pressing force transmission member.
[0019]
When the lead frame 41 (41 a, 41 b) is set in such a molding die 18, the spring force from the compression coil spring 36 passes through the pressing force transmission member 35, the pillar receiver 34, and the pillar 32 to each upper cavity block 24. Applied as a pressing force. Therefore, even if the thickness of each lead frame 41 varies, the upper cavity block 24 is pressed well according to the thickness of the lead frame 41, so that unnecessary gaps are not formed and resin burrs are generated. Absent. Therefore, the labor of the resin deburring operation for the product is not required, and the deterioration of the mold accuracy due to the resin burr adhering to the mold 18 and the cleaning effort can be reduced.
[0020]
However, although the above-described molding die 18 can cope with a workpiece having a variation in the thickness of each plate, even a single plate such as a plastic substrate having a multilayer structure can vary in thickness depending on the location. Is difficult to respond. Therefore, when manufacturing a BGA type semiconductor package, as shown in FIG. 2, the upper cavity block 44 corresponding to one plastic substrate 43 of the molding die 42 is divided into each package forming cavity 45. . One or more sets of pressing force application mechanisms 47 (47a... 47d) similar to the pressing force application mechanism 31 are installed for each divided block 46 (46a... 46d) having the cavity 45. Reference numeral 48 denotes an upper chase block, 49 denotes an ejector plate, 50 denotes an upper mold base, 51 denotes a pillar, 52 denotes a pillar receiver, 53 denotes a pressing force transmission member, and 54 denotes a compression coil spring serving as a pressing force source. By the way, if a laminated body of disc springs is installed in the upper chase block, the upper cavity block is restricted by the space of the disc spring and is difficult to divide.
[0021]
When the upper cavity block 44 is divided in this way, even when the plastic substrate 43 is set, the thickness of the substrate 43 varies, and even if the plate thickness varies depending on the location, it is arranged according to the thickness of each location. Each of the divided blocks 46 is pressed well. Therefore, an unnecessary gap is not generated between the plastic substrate 43 and the upper cavity block 44 at any package forming location, and no resin burr is generated. When molding a BGA type semiconductor package, the lower cavity block is not provided with a cavity for molding the package, and the upper surface is flattened.
[0022]
In the mold 18 described above, the upper center block 23 does not move, and only the upper cavity blocks 24 on both sides move. Therefore, the lower center block 27 is provided with pot rows for respectively containing tablets (molding materials), the runners are extended in both directions from the cull provided on the upper center block 23 in opposition to the pots, and the upper cavity on each side. When connected to the corresponding cavity 29 of the block 24, each runner crosses the bonding surface between the upper center block 23 and the upper cavity block 24, so that the resin leakage occurs on the bonding surface with the upper center block 23 due to the movement of the upper cavity block 24. Occurred.
[0023]
Therefore, the upper chase block is not provided with the upper center block, but only two upper cavity blocks are provided. At this time, as shown in FIG. 3, runners 56 (56a,... 56j) are alternately projected in opposite directions from the respective culls 55 (55a,... 55j) in the order of the cull rows. Each of the contained cavities 57 (57a,... 57e) and the runner 56 and the cull 55 connected to each of the cavities 57 are integrally included to form one upper cavity block 58, and the other cavity row Each of the contained cavities 59 (59a,... 59e) and the runner 56 and the cal 55 connected to each of the cavities 59 are integrally included to form the other upper cavity block 60.
[0024]
Then, the vicinity of each cull 55 is formed in a rectangular protrusion 61 (61a,... 61j), and when these protrusions 61 are alternately fitted, the upper cavity blocks 58 and 60 are joined to each other, It can be slidable in the direction and can be mounted on the upper chase block. Note that the corners of the upper cavity block 58 adjacent to the protrusions 61a and the corners of the upper cavity block 60 adjacent to the protrusions 61j are respectively formed in similar protrusions 62 and 63 for fitting.
[0025]
If the upper center block is eliminated in this way, the runners 56 do not cross the joint surface. Therefore, even if the upper cavity blocks 58 and 60 are moved, the resin leakage from the runners 56 naturally occurs. Disappear. Also, the lower chase block is provided with the same lower cavity block corresponding to each of the upper cavity blocks 58 and 60, and the lower center block is eliminated. When both upper cavity blocks 58 and 60 are used for a workpiece such as a plastic substrate whose thickness varies depending on the location, a two-dot chain line that divides each upper cavity block 58 and 60 into parts having cavities 57 and 59. Divide and use at the position.
[0026]
In the above embodiment, as a pressing force application mechanism, a pillar that transmits the pressing force is inserted into a hole provided in the upper chase block, the tip of the pillar is brought into contact with the upper cavity block, and the rear end of the pillar is The upper mold base is provided with a receiving pillar receiver, the tip of the pressing force transmission member that transmits the pressing force is brought into contact with the pillar receiver, and a pressing force source that applies the pressing force to the pressing force transmission member is provided on the upper mold base. However, the pressing force application mechanism may be configured without using the pillar receiver and the pressing force transmission member, and the pressing force may be directly applied to the rear end of the pillar from the pressing force source.
[0027]
Further, in the above embodiment, when the division block is formed, the division line is the boundary line of the division block having the adjacent cavities, but the division lines 65 are provided around the cavities 64 as shown in FIG. Each divided block 66 having the cavity 64 may be formed. In addition, 67 is an upper chase block, 68 is an upper cavity block, 69 is an upper center block, 70 is a runner, and 71 is a cull.
In the above embodiment, the pressing force application mechanism is installed on the upper mold, but a similar pressing force application mechanism may be installed on the lower mold.
[0028]
【The invention's effect】
According to the present invention described above, in the first aspect of the present invention, it is only necessary to insert the pillar of the pressing force application mechanism into the chase block, and the position of the pillar is not easily limited by the ejector pin inserted through the chase block. Therefore, it is possible to select a pressing position to be applied to the cavity block, and it is easy to distribute and apply the pressing force evenly. It is also easy to change the number of pillars. Moreover, since the pressing force source constituting the pressing force application mechanism is installed on the mold base, the degree of freedom of the pressing force application mechanism is increased. Therefore, it is easy to adjust the magnitude of the pressing force and to obtain a large pressing force. And according to the plate | board thickness of each place in one workpiece | work, it can each press well with the division | segmentation block which has the cavity arrange | positioned there. Therefore, even if the thickness of one workpiece varies, an unnecessary gap does not occur at the time of molding and no resin burr is generated.
[0029]
According to the second aspect of the present invention, it is only necessary to insert the pillar of the pressing force application mechanism into the chase block, and the position of the pillar is not easily limited by the ejector pin inserted into the chase block. Therefore, it is possible to select a pressing position to be applied to the cavity block, and it is easy to distribute and apply the pressing force evenly. It is also easy to change the number of pillars. Moreover, since the pressing force source constituting the pressing force application mechanism is installed on the mold base, the degree of freedom of the pressing force application mechanism is increased. Therefore, it is easy to adjust the magnitude of the pressing force and to obtain a large pressing force. The chase block includes only the cavity block , and the cavity block is integrally formed including the runner and the cull connected to each of the plurality of cavities. No resin leakage from the resin, and no resin burrs are generated.
According to a third aspect of the present invention, the divided block having the cavities disposed therein is further divided according to the plate thickness of each place in one work by dividing each portion having the cavities of the cavity block. Each can be pressed well. Therefore, even if the thickness of one workpiece varies, an unnecessary gap does not occur at the time of molding and no resin burr is generated.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part seen from the front side of a mold using a movable cavity method to which the present invention is applied.
FIG. 2 is a longitudinal sectional view of the main part of the upper mold as seen from the side surface showing a modification of the mold for molding by the movable cavity method.
FIG. 3 is a bottom view of both upper cavity blocks in a joined state showing a modification of an upper cavity block provided in a mold for molding using the movable cavity method.
FIG. 4 is a bottom view of the vicinity of one upper cavity block showing another modification of the upper cavity block provided in the mold for molding by the movable cavity method.
FIG. 5 is a longitudinal sectional view of a main part viewed from the front side of a mold for molding by a conventional movable cavity method.
FIG. 6 is a longitudinal sectional view of a main part viewed from a side surface of a mold for molding using the movable cavity method.
[Explanation of symbols]
18, 42 ... Molding mold 19, 20 ... Upper and lower mold 21, 50 ... Upper mold base 22, 48, 67 ... Upper chase block 23, 69 ... Upper center block 24, 44, 58, 60, 68 ... Upper cavity block 25 ... Lower mold base 26 ... Lower chase block 27 ... Lower center block 28 ... Lower cavity block 29, 45, 57, 59, 64 ... Cavity 30 ... Lower ejector plates 31, 47 ... Pressing force application mechanism 32 51 ... Pillar 33, 49 ... Upper ejector plate 34, 52 ... Pillar receiver 35, 53 ... Pressing force transmitting member 36, 54 ... Compression coil spring 38 ... Spring force adjusting member 41 ... Lead frame 43 ... Plastic substrate 46, 66 ... Divided blocks 55, 71 ... Cal 56, 70 ... Runners 61, 62, 6 ... protrusion

Claims (3)

In the mold for molding using the movable cavity method in which a chase block having a cavity block is installed on a mold base and a pressing force applying mechanism is provided to move the cavity block by applying a pressing force, the above-mentioned one workpiece dividing the corresponding cavity block into a plurality, for each divided block having the cavity, there by adding pressing force respectively installed a pressing force applying mechanism to be movable, as a respective pressing force applying mechanism, chase block A pillar for transmitting a pressing force is inserted into a corresponding hole provided in the die, one end of the pillar is brought into contact with the corresponding divided block, and a pressing force source for applying a pressing force to the other end of the pillar is provided in the mold base. Molding mold by the movable cavity method. In a mold using a movable cavity method in which a chase block with a cavity block is installed on the mold base and a pressing force application mechanism is provided to move the cavity block by applying a pressing force to the cavity block. The cavity block corresponding to the one workpiece is integrally formed including a runner and a cull connected to each of the plurality of cavities, and each portion having the cavity of the cavity block is pushed into the cavity block. A pressing force application mechanism that moves by applying pressure is installed. As each pressing force application mechanism, a pillar that transmits the pressing force is inserted into a corresponding hole provided in the chase block, and one end of the pillar is inserted into the corresponding part . A pressing force source that applies pressure to the other end of the pillar is installed on the mold base. Molding die by the movable cavity method characterized by Rukoto. 3. The movable cavity system according to claim 2, wherein each portion having the cavity of the cavity block is divided, and a pressing force application mechanism is provided for each of the divided blocks so as to be moved by applying a pressing force thereto. Molding mold.

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