JP5987190B2 - Mold for sealing semiconductor device and semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device sealing mold for resin-sealing a semiconductor element by transfer molding and a semiconductor device manufactured using the mold.

  As a conventional resin sealing method for semiconductor devices, a technique called transfer molding is employed. This is done by filling a mold with a thermosetting resin (epoxy resin, etc.) melted by heating and pressurizing via a runner and nozzle, and thermosetting the member to be sealed (substrate mounted with a semiconductor element, etc.). This is a method of sealing with a functional resin.

  In transfer molding, a thermosetting resin whose curing is accelerated by a chemical reaction at a high temperature is used. After the molten sealing resin material is filled in a mold, it is kept at a high temperature until the curing sufficiently proceeds. There is a problem that time is required and cycle time is long and productivity is low.

  In order to accelerate the curing of the thermosetting resin, the input heat amount may be increased, but the viscosity of the molten sealing resin material increases remarkably with the curing. For this reason, if the mold temperature is set high, the viscosity rapidly increases before the sealing resin material is filled into the mold, and the fluidity of the molten sealing resin material may be lost and unfilled. is there. A mechanism for adjusting the volume of the sealing resin material filled in the mold is referred to as a cull part, and is coupled to a plurality of mold product parts via a runner. The cull portion has a certain volume due to the resin volume adjustment mechanism, and the curing rate of the sealing resin material in the cull portion is slow.

  Further, since it is necessary to raise the temperature of the entire mold having a large heating volume to a high temperature of about 180 ° C. and to maintain the mold temperature at a high temperature, a large number and capacity of heat sources are required. Further, when the number of heat sources increases, it is necessary to secure a region for arranging the heat sources, and accordingly, the volume of the entire mold is increased. For the above reasons, there has been a problem that the manufacturing cost of the transfer molding die becomes expensive.

  In Patent Document 1, in a mold for sealing a semiconductor device in which a sealing member mounted with a semiconductor element is resin-molded by transfer molding in upper and lower molds, the upper mold includes a cull part and a product part. A first upper mold and a second upper mold stacked on top of the first upper mold, a heat insulating layer interposed between the first upper mold and the second upper mold, and between the cull portion and the heat insulating layer, The heating source is disposed on the axis of the plunger that is movably moved back and forth within the pot portion formed in the lower mold of the mold.

  By disposing a heating source on the advancing / retracting shaft of the plunger connected to the cull portion, heating is performed around the cull portion having a low curing speed, and curing of the resin sealing material can be promoted.

JP 2007-287925 A

  However, since the heat source and the heat insulating material are disposed only in the first upper mold, it is expected that the heating of the mold becomes local and a temperature gradient is generated between the upper mold and the lower mold. When variation occurs in the curing behavior of the sealing resin material due to the temperature gradient, the curing time becomes long, and local sink and warp occur. In addition, it is necessary to keep the upper and lower molds in the `` open '' state during mold cleaning work performed between moldings, placement of the sealing material and sealing resin material on the mold, It is conceivable that the heat just escapes from the lower mold having no heating source, the lower mold temperature is lowered, and the temperature difference between the upper and lower molds is further increased.

The mold for sealing a semiconductor device according to the present invention includes an upper mold composed of a second upper mold that covers the first upper mold and the first upper mold, and a second that covers the first lower mold and the first lower mold. A lower die constituted by a lower die, a pot portion provided in a second lower die for inserting a tablet of a sealing resin material, a plunger arranged to move forward and backward in the pot portion, and a semiconductor element for sealing resin Semiconductor device sealing provided with a product part to be transfer-molded with a material, a cull part arranged on the plunger shaft for adjusting the volume of a sealing resin material to be filled, and a gate part connecting the product part and the cull part A first heat source disposed in the first upper mold in the vicinity of the cull portion; a second heat source disposed in the first lower mold; and the upper mold and the lower mold. and an externally at least one protrusion into the product portion, said second upper and said second lower , The Ri Do material excellent heat insulating property than the first upper and the first lower die, wherein the protruding portion is towards the outer side of the product portion is made of a material excellent thermal insulating properties Is.

  2. The semiconductor device sealing according to claim 1, wherein a heat insulating layer is provided between the first upper mold and the second upper mold and between the first lower mold and the second lower mold. Mold.

Protruding part from the outside to the product part is provided in at least one of the upper mold and the lower mold,
3. The mold for sealing a semiconductor device according to claim 1, wherein the protruding portion is made of a material having better heat insulation on the outer side than on the product portion side.

  A semiconductor device manufactured using the mold for sealing a semiconductor device according to any one of claims 1 to 3.

  According to this invention, the upper mold composed of the first upper mold and the second upper mold covering the first upper mold, and the lower mold composed of the second lower mold covering the first lower mold and the first lower mold. Product part for transfer molding a semiconductor element with a sealing resin material, a pot part that is provided in the second lower mold and into which a tablet of sealing resin material is placed, a plunger that is disposed so as to be movable back and forth in the pot part And a mold for semiconductor device sealing that includes a cull part that adjusts the volume of the sealing resin material that is disposed on the axis of the plunger and a gate part that connects the product part and the cull part, A first heat source disposed in the first upper mold in the vicinity of the cull part and a second heat element disposed in the first lower mold so as to cover the product part in the horizontal direction or the vertical direction so as to cover the product part. The second upper mold and the second lower mold are more thermally insulating than the first upper mold and the first lower mold. Since semiconductor device sealed mold made of a material excellent, can warm a short time the entire mold, to suppress the escape of heat to the mold outside, it is possible to reduce the variation in the curing behavior in the mold.

It is a perspective view of the metal mold | die for semiconductor device sealing by Embodiment 1 of this invention. 1 is a cross-sectional view of a mold center part of a mold for sealing a semiconductor device according to a first embodiment of the present invention. It is sectional drawing of the protrusion apparatus arrangement | positioning part of the metal mold | die for semiconductor device sealing by Embodiment 1 of this invention. 1 is a cross-sectional view of a central portion of a semiconductor device of a mold for sealing a semiconductor device according to a first embodiment of the present invention. It is a figure which shows the flow of the heat | fever in the metal mold | die for semiconductor device sealing of Embodiment 1 of this invention. It is a figure which shows the structural example of the 2nd metal mold | die by Embodiment 1 of this invention.

Embodiment 1 FIG.
FIG. 1 is a perspective view of a mold for sealing a semiconductor device according to Embodiment 1 of the present invention. 2, FIG. 3, and FIG. 4 are cross-sectional views of the mold for sealing a semiconductor device according to the first embodiment of the present invention. More specifically, FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG. 4 is a cross-sectional view taken along the line CC of FIG. 1 and is a cross-sectional view of the central portion of the semiconductor device of the mold for sealing the semiconductor device. FIG. 1 shows the upper and lower molds 10 and 20 of a batch type having four product parts 35.

  The semiconductor device sealing mold includes an upper mold 10, a lower mold 20, a pot portion 30, a plunger 31, and a heat source 32 as main components. At the time of sealing the semiconductor device, a material to be sealed on which a semiconductor element is mounted is disposed between the upper mold 10 and the lower mold 20, and after the sealing resin material 34 is put into the pot portion 30, the upper mold When the mold 10 and the lower mold 20 are closed, a cull portion 36 that connects the pot portion 30 and the product portion 35 is formed, and the plunger 31 pushes the sealing resin material 34 in the pot portion 30 so that the product portion 35, that is, the semiconductor The material to be sealed, which is filled in the apparatus and disposed inside the product portion 35, is sealed.

  The upper mold 10 and the lower mold 20 of the semiconductor device sealing mold include a first upper mold 11 including a product part 35 and a cull part 36, a first part including a product part 35, a cull part 36, and a pot part 30. The lower mold 21, the first upper mold 11, and the first lower mold 21 are divided into a second upper mold 12 and a second lower mold 22 that are overlaid on the bottom surface portions, respectively.

  The first upper mold 11 and the first lower mold 21 are made of a material having excellent thermal conductivity in order to efficiently transmit the amount of heat input from the heat source 32. By using a material having excellent thermal conductivity, the cross-sectional area of the mold through which heat is conducted can be reduced, and as a result, the first upper mold 11 and the first lower mold 21 constituting the first mold are thinned. it can. The thickness of the first mold is preferably as thin as possible as long as deformation and damage due to resin pressure during molding do not occur. As the mold is thinned, mold miniaturization is achieved, leading to a reduction in mold manufacturing costs.

  Examples of materials having excellent thermal conductivity that constitute the first mold include steel materials, copper and aluminum, alloys thereof, carbon, carbon fiber-impregnated composite materials, other metal materials, SiC, AlN, BN, etc. This is the result of sealing the surface of the ceramic material.

  With this configuration, since the heating volume of the mold can be locally limited, the amount of heat input from the heat source 32 disposed in the first mold can be conducted to the entire mold, and the mold can be quickly heated.

  Moreover, it is preferable to comprise the 1st metal mold | die thinned from the low elastic modulus material compared with the steel material used for a general metal mold | die material. By manufacturing the mold with a material having a low elastic modulus, the ratio of the deformation amount of the first mold due to the resin pressure during molding increases, but the strain amount is reduced by reducing the thickness of the first mold. Therefore, the durability of the mold due to repeated strain can be secured.

  In order to heat the entire upper mold 10 and lower mold 20 to the molding temperature, the heat of the heat source 32 disposed immediately above the cull part 36, which is the central part of the first mold, is moved in the horizontal direction. The first mold is formed so as to cover the horizontal direction of the heat source 32, and when the mold is closed, the first molds (11, 21) of the upper mold 10 and the lower mold 20 are in contact with each other. Is formed so that the outer peripheral surface of the pot portion 30 is covered with the first mold of the upper die or the lower die, so that the sealing resin material put into the pot portion 30 is directly above the cull portion 36. It can heat with the heat source 32 arrange | positioned. Further, the upper die or the lower die on the side where the heat source 32 directly above the cull portion 36 of the first mold is not disposed is heated so as to cover the horizontal and vertical directions of the product portion away from the heat source 32 directly above the cull portion 36. A heat source is arranged so that heat is transmitted to the entire mold.

  The heat source 32 disposed in the first upper mold 11 and the first lower mold 21 may be either a heater by resistance heat generation, a temperature control vacuum pipe by water or oil, or induction heating by a coil, and a mechanism using both of them. It may be configured.

The second upper mold 12 and the second lower mold 22 that are superposed on the bottom surfaces of the first upper mold 11 and the first lower mold 21, each having a heat source 32 and made of a material having excellent heat conductivity, have high strength. Further, it is preferable to be made of a material having excellent heat insulation performance. For example, compounds composed of two or more of MgO, SiO ₂ and Al ₂ O ₃ , porous ceramic materials such as ZrO ₂ , plastic materials such as PEEK (polyether ether ketone) and PPS (polyphenylene sulfide resin), glass This is true for materials. With this configuration, it is possible to suppress the amount of heat input to the first mold from being released to the outside of the mold. Therefore, even when the mold is opened, fluctuations in the mold temperature are suppressed, and molding is repeated efficiently with low power consumption. You can do it.

  FIG. 5 is a diagram showing a heat flow in the semiconductor device sealing mold according to the first embodiment of the present invention. More specifically, it is a cross-sectional view taken along the line B-B in FIG. 1, a cross-sectional view of a protruding device arrangement portion of a semiconductor device sealing mold, and a view corresponding to FIG. 3. In order to explain the flow of FIG. The schematic diagram shows that heat is transferred from the heat source 32 indicated by the black circle in the direction indicated by the arrow.

  The second upper mold 12 and the second lower mold 22 may be processed by pulling out the volume of the first upper mold 11 and the first lower mold 21 from a block-shaped heat insulating material, or a plate-shaped heat insulating material. A plurality of stacked sheets may be fixed with bolts or the like. FIG. 6 is a diagram showing a configuration example of the second mold. A heat insulating material (heat insulating material B) obtained by pulling out a predetermined shape in the center between two plate-shaped heat insulating materials (heat insulating material A), that is, a shape slightly larger than the first upper mold 11 and the first lower mold 21. By interposing, a heat insulation layer of air having better heat insulation performance than the solid heat insulation material may be formed, and the heat insulation effect may be further enhanced. The two plate-like heat insulating materials (the heat insulating material A) and the heat insulating material (the heat insulating material B) can be fixed with bolts or the like.

  That is, it is made of a material having excellent heat conductivity, and is excellent in heat insulation formed so as to be in contact with the outer surfaces of the first upper mold 11 and the first lower mold 21 and to cover the surfaces other than the surface facing the upper mold or the lower mold. In the second upper mold 12 and the second lower mold 22 made of materials, a plate-shaped heat insulating material with the center pulled out in an arbitrary shape is sandwiched between two plate-shaped heat insulating materials, and the plate shapes having different shapes The second upper mold 12 and the second lower mold 22 can be formed by fixing a plurality of stacked heat insulating materials with bolts or the like.

  In this way, a heat insulating layer is provided between the first upper mold 11 and the second upper mold 12 and between the first lower mold 21 and the second lower mold 22. By forming a heat insulation layer of air having better heat insulation than a solid between the two plate-like heat insulation materials, heat escaped into the first upper mold 11 and the first lower mold 21 to the outside of the mold Therefore, even when the mold is opened, fluctuations in the mold temperature can be suppressed, and molding can be repeated efficiently with low power consumption.

  The shape of the gate portion 38 that fills the product portion 35 with the sealing resin material 34 is preferably small in cross-sectional area and large in surface area. When the cross-sectional area is constant, a trapezoidal shape is most desirable. The flow rate when the sealing resin material 34 passes through the gate portion 38 having a small cross-sectional area is increased. When the sealing resin material 34 flows along the mold surface, shear heat generation due to friction occurs at the contact surface. The amount of heat generated by shear heat generation increases as the flow rate of the sealing resin material 34 increases. Further, the larger the surface area, the larger the resin volume that contacts the high temperature portion of the sealing resin material 34 that passes through the gate portion 38. Due to the above effect, the amount of heat received by the sealing resin material 34 from the mold surface is increased and the curing reaction is promoted.

  When the semiconductor device is sealed, the air remaining in the mold is exhausted by the vacuum exhaust passage 39 in order to efficiently fill the entire mold with the sealing resin material 34 pushed into the mold by the plunger 31. To do. The vacuum exhaust passage 39 is preferably provided so as to communicate with the gate portion 38 of the product portion 35 that is finally filled with the sealing resin material 34 in the mold. By efficiently exhausting the residual air in the mold, the fluidity of the molten sealing resin material 34 is improved. As this effect, the filling time of the sealing resin material 34 can be shortened and molding defects such as unfilled and voids can be suppressed.

  Residual air in the mold is exhausted not only by the vacuum exhaust path 39 but also by the gas vent 40 provided in the product part 35 and the cull part 36. In order for the gas vent 40 to function efficiently, it is required that only the residual air in the mold flows into the gas vent 40 while suppressing the inflow of the molten sealing resin material 34 into the gas vent 40. For this reason, the shape of the gas vent 40 is preferably a trapezoidal shape having a small cross-sectional area and a large surface area. Since the gas vent 40 having a small cross-sectional area has a large pressure loss at the inlet, it is difficult for a high-viscosity fluid to enter. Even if the sealing resin material 34 flows into the gas vent 40, the inflowing resin is cured in the vicinity of the entrance by increasing the surface area, and further inflow of the resin is suppressed.

  Residual air in the mold is pushed out at the front end of the molten resin when the sealing resin material 34 is filled in the mold. However, the air that has flowed through the flow of the molten resin tends to remain in places where the cull portion 36 flows into the product portion 35 and where the flow direction of the sealing resin material 34 changes inside the product portion 35. . For this reason, it is preferable to provide the gas vent 40 at a location where the flow direction of the sealing resin material 34 changes, and it is preferable to provide it at the four corners of the product portion 35 and the cull portion 36. Further, a gas vent 40 may be provided on the opposite side of the gate portion 38 disposed in the product portion 35.

  The present mold is an ejecting apparatus for releasing the sealing resin material 34, which is filled after the product part 35 and the cull part 36 and is held for a predetermined time, from the upper mold 10 and the lower mold 20 (Projecting part). As the ejecting device, any method such as a pin, a sleeve, a plate, and a ring may be used, and an ejecting device using air pressure may be used as an auxiliary to these ejecting methods. In the present embodiment, a pin protrusion method using the ejector pins 41 will be described. The ejector pin 41 is preferably made of a material having excellent thermal conductivity, such as a conventionally used high-speed tool steel. In the ejector pin 41 that travels inside the mold when the semiconductor device is released, part or all of the surface of the ejector pin 41 disposed in the second mold is thermally conducted when the sealing resin material 34 is cured and held. Cover with a low-rate material.

With this configuration, the amount of heat that escapes to the outside of the mold via the ejector pins 41 can be suppressed, so that the mold temperature can always be maintained at a high temperature, and the molding can be performed efficiently and repeatedly. As a method of covering the ejector pin 41, a part made of a material having low thermal conductivity may be fixed to the outside of the metal material constituting the ejector pin 41 with a bolt, or a thin film is processed by thermal spraying or plating. The method is fine. Further, the ejector pins 41 may be disposed not only in the lower mold 20 and the upper mold 10 but only in one of them. Components arranged on the surface of the ejector pin 41 and a porous ceramic material such as a compound composed of two or more of MgO, SiO ₂ , Al ₂ O ₃ and ZrO _{2 which} are excellent in heat insulation performance as a thin film material, PEEK (polyether) Plastic materials such as ether ketone) and PPS (polyphenylene sulfide resin), glass materials, and resin materials such as fluororesin are preferable. The diameter of the ejector pin 41 should be as small as possible in terms of strength. A similar process may be performed on the core pin 37.

  A heat source disposed in the first upper mold 11 and the first lower mold 21 in the product section 35 and the cull section 36 formed in the first upper mold 11 and the first lower mold 21 made of a material having excellent thermal conductivity. The sealing resin material 34 melted by 32 is filled and cured after the sealing resin material 34 filled in the product part 35 and the cull part 36 formed in the first upper mold 11 and the first lower mold 21 is cured. For the purpose of taking out the semiconductor device made of the sealing resin material 34 from the mold, an ejector device (ejector pin 41) provided to penetrate at least one of the first upper mold 11 and the first lower mold 21 is used. ), When the molten sealing resin material 34 made of a material such as copper or aluminum having excellent thermal conductivity and filled in the product part 35 and the cull part 36 is cured and held, the first upper mold 11 and the first mold 11 1 Outside the lower mold 21 Some or all of the ejector (ejector pin 41) surface that location, are covered with material having small thermal conductivity such as ceramics. As described above, a protruding portion from the outside to the product portion is provided on at least one of the upper die 10 and the lower die 20, and the protruding portion is a material having better heat insulation on the outer side than on the product portion side. ing.

  In addition, by forming a protrusion device having a tip located on the surface of the product portion provided on at least one of the first upper mold 11 and the first lower mold 21 with a material having excellent thermal conductivity, The heat from the heat source arranged in the mold 11 and the first lower mold 21 can be efficiently spread to the sealing resin material 34, and a part of the surface is covered with a material having a low thermal conductivity, so that the protrusion is made. Since the amount of heat that escapes to the outside of the mold through the surface of the apparatus can be suppressed, the mold temperature can always be maintained at a high temperature, and the molding can be performed efficiently and repeatedly with low power consumption.

  In addition, when starting a mold due to changes in semiconductor device specifications, die wear, or damage, it is only necessary to produce the first mold made of a material with excellent thermal conductivity, which reduces the cost of mold production. Reduction can be achieved.

  As described above, in a semiconductor device sealing mold that seals a material to be sealed such as a substrate on which a semiconductor element is mounted by transfer molding in upper and lower molds, copper or aluminum having excellent thermal conductivity The first mold is moved so that the heat of the heat source arranged immediately above the cull part, which is the central part of the first mold having the product part and the cull part, moves in the horizontal direction. A flat surface is formed to cover the horizontal direction of the heat source, and heat can be transferred by contacting the upper and lower first molds when the mold is closed. When the upper mold or the first mold of the lower mold is covered, the sealing resin material put in the pot portion is heated by a heat source arranged just above the cull portion. In addition, in the upper mold or the lower mold on the side where the heat source directly above the cull part of the first mold is not disposed, a heat source for heating is disposed so as to cover the horizontal and vertical directions of the product part away from the heat source directly above the cull part, A heat source is arranged so that heat is transmitted to the entire mold. Further, the first mold having these heat sources is covered with a second mold made of a material having excellent heat insulating properties such as ceramics except for the surface facing the upper mold or the lower mold.

This makes it possible to raise the temperature of the entire mold with a limited heating volume in a short time, suppress the escape of heat from the mold surface to the outside of the mold, and keep the entire mold constantly at a high temperature, enabling efficient and repeated molding. Is possible. In addition, by disposing the heat source so that the heat is spread throughout the mold, it is possible to reduce the variation in the curing behavior in the mold, so it is expected to be effective in shortening the curing time and reducing sink marks and warpage due to curing shrinkage. it can. Furthermore, the mold manufacturing cost can be reduced by reducing the thickness and size of the mold.
That is, an upper mold constituted by a second upper mold covering the first upper mold and the first upper mold, and a lower mold constituted by a second lower mold covering the first lower mold and the first lower mold, A pot portion provided in the second lower mold for inserting a tablet of the sealing resin material; a plunger disposed so as to be movable back and forth in the pot portion; a product portion for transfer molding of the semiconductor element with the sealing resin material; A mold for sealing a semiconductor device including a cull part that adjusts the volume of a sealing resin material that is disposed on a shaft and a gate part that connects the product part and the cull part, in the vicinity of the cull part The first heat source disposed in the first upper mold and the second heat source disposed in the first lower mold away from the first heat source so as to cover the product portion in the horizontal direction or the vertical direction. The second upper mold and the second lower mold have better heat insulation than the first upper mold and the first lower mold. Since semiconductor device sealed mold made of fees can be heated at a short time the entire mold, to suppress the escape of heat to the mold outside, it is possible to reduce the variation in the curing behavior in the mold.

10 Upper mold, 11 First upper mold, 12 Second upper mold, 20 Lower mold, 21 First lower mold, 22 Second lower mold, 30 Pot part, 31 Plunger, 32 Heat source, 34 Sealing resin material, 35 Product part, 36 Cal part, 37 Core pin, 38 Gate part, 39 Vacuum exhaust path, 40 Gas vent, 41 Ejector pin.

Claims (2)

An upper mold composed of a first upper mold and a second upper mold covering the first upper mold;
A lower mold composed of a first lower mold and a second lower mold covering the first lower mold;
A pot portion that is provided in the second lower mold and into which a tablet of a sealing resin material is charged;
A plunger disposed so as to be movable back and forth in the pot portion;
A product part for transfer molding a semiconductor element with the sealing resin material;
A cull portion that is arranged on the axis of the plunger and adjusts the volume of the sealing resin material to be filled;
A mold for sealing a semiconductor device comprising a gate portion connecting the product portion and the cull portion,
A first heat source disposed in the first upper mold in the vicinity of the cull portion;
A second heat source disposed in the first lower mold;
Providing at least one of the upper mold and the lower mold with a projecting part from the outside to the product part,
Said second upper and said second lower die, Ri Do from the material excellent heat insulating property than the first upper and the first lower die,
The protruding part is made of a material having better heat insulation on the outer side than on the product part side, and is a mold for sealing a semiconductor device.   2. The semiconductor device sealing according to claim 1, wherein a heat insulating layer is provided between the first upper mold and the second upper mold and between the first lower mold and the second lower mold. Mold.

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