JP5124347B2 - Semiconductor mounting substrate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor mounting substrate on which a light emitting device such as an LED, a semiconductor device such as a CPU, and the like are mounted on a substrate, and a manufacturing method thereof.

  2. Description of the Related Art In recent years, countermeasures against heat generation have become a problem in light emitting devices using LED as a light source, which has been widely used in place of incandescent light bulbs as a countermeasure against global warming, and as a countermeasure against global warming.

Conventional semiconductor device cooling methods include attaching a heat sink (heat sink) to the back side of the semiconductor mounting substrate, molding the semiconductor device and the heat sink integrally, attaching the heat sink to the semiconductor device from the outside, A water-cooled cooling device is used in which a heat sink and a cooling fan are used in combination, or a refrigerant is circulated by a pump instead of a heat sink. Alternatively, a power module substrate in which a ceramic substrate on which the power module is mounted is screwed to a water-cooled heat sink and joined is also proposed (Patent Document 1).
JP 2001-35982 A

However, when the heat sink is directly attached to a semiconductor package or substrate, the heat dissipation characteristics cannot be secured sufficiently, the adhesive is deteriorated and peeling is likely to be promoted, and the electrical insulation from the wiring pattern is taken into consideration. There must be.
Further, if the heat sink is bonded to the entire surface of the resin substrate, the weight of the product increases, and the substrate is likely to warp due to the difference in linear expansion coefficient between the sealing resin and the metal, making it difficult to perform subsequent processing.

  In particular, in a light-emitting device using a high-intensity LED, deterioration of the semiconductor device is promoted by heat generation, and the illuminance is lowered and the product life tends to be shortened. Further, since the LED includes ultraviolet rays in the irradiation light, a decrease in the reflectivity of the reflector and deterioration due to white turbidity of the transparent resin cause a shortening of the lifetime, and the deterioration cycle due to the ultraviolet rays is promoted by heat generation. Furthermore, the manufacturing cost by replacing the deteriorated parts increases.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to use a semiconductor mounting substrate and existing equipment that can efficiently dissipate heat generated from the semiconductor device mounted on the substrate by a heat sink, and it is inexpensive and highly productive. An object of the present invention is to provide a method for manufacturing a semiconductor mounting substrate in which a substrate and a heat sink can be firmly assembled.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, a mounting board in which a through hole smaller than the mounting area of the semiconductor device is formed at a part where the semiconductor device is mounted, and a protrusion is fitted into the through hole on the opposite side of the mounting board from the semiconductor device mounting surface A heat sink having a flat plate portion larger than the mounting area of the semiconductor device , wherein the heat sink has a flat plate portion larger than a mounting area of the semiconductor device. characterized in that the sealed around exposed flat portion on the substrate surface opposite to the sealing resin said filling anyone portion or the sealing resin on the surface side of the chamfered portion are retaining held on the substrate integrally And
One or a plurality of heat sinks are provided, and the total area of the flat plate portion is formed to be equal to the area of the surrounding sealing resin.
The heat sink is connected to the heat radiating fins via heat radiating fins attached to the flat plate portion or heat pipes connected to the flat plate portion.

Further, as a method for manufacturing a semiconductor mounting substrate, a step of closing a center hole on one surface of a metal frame and sticking a heat resistant sheet, and a heat resistant sheet having a recess formed by closing the center hole of the metal frame A step of mounting a mounting substrate on which a through hole is formed at a mounting position on which a semiconductor device is mounted and a protrusion is fitted into the through hole and a heat sink is assembled, with the mounting surface facing down; and the metal frame The body and the sealing resin are carried into the mold, or the sealing resin is supplied onto the mounting substrate around the heat sink and then the metal frame is carried into the mold, and the mounting is performed by the mold. A step of clamping the substrate and the metal frame, and filling and curing a sealing resin in a gap around the heat sink while heating and pressing.
In addition, a dam portion protrudes from one clamping surface of the mold die, and when the mold die clamps the metal frame and the mounting substrate, the dam portion covered with the heat-resistant sheet contacts the side surface of the substrate. It is characterized by touching.

If the semiconductor mounting substrate according to the present invention is used, the flat heat sink is assembled by directly or indirectly contacting the semiconductor device by inserting a protrusion into the through hole on the surface of the mounting substrate opposite to the semiconductor device mounting surface. Therefore, the heat generated in the semiconductor device can be guided to the back side of the substrate and efficiently dissipated. In particular, in a light-emitting device using a high-intensity LED, the product life of a semiconductor device that easily deteriorates due to heat generation can be extended.
In addition, the heat sink is exposed to a flat plate and the outer periphery is sealed with a sealing resin, and is held integrally with the substrate. Since the coefficient of linear expansion of the material does not change much, it can be held integrally without being detached from the mounting substrate.
Further, a drooping portion or a chamfered portion is formed on the outer peripheral edge portion of the heat sink, and an anchor effect is generated by filling a sealing resin on the surface side of the drooping portion or the chamfered portion so that the heat sink is firmly attached to the substrate. Can be held.
The heat sink is provided singular or plural, the total area of the flat plate portion is formed to be equal properly and the area of the sealing resin surrounding the heat sink without being diffused into heat substrate generated in the semiconductor device Heat is collected and heat can be efficiently dissipated.
In addition, when the heat sink is connected to the heat radiating fin via a heat radiating fin or a heat pipe attached to the flat plate portion, the heat dissipation can be further enhanced. In addition, by dissipating heat to the outside by the heat pipe, heat dissipation can be improved with a free layout without increasing the thickness of the mounting substrate itself.

Also, clamp the mounting substrate with the heat sink assembled, and press the melted sealing resin into the gap around the heat sink and cure it while heating and pressurizing, or supply the sealing resin into the gap around the heat sink Since the mold mold is clamped from and the heat sink can be integrally assembled and held on the substrate by using either compression molding that fills and cures the sealing resin while heating and pressurizing the gap around the heat sink, A mounting board on which a heat sink is assembled using existing equipment can be mass-produced at low cost.
In addition, a mounting substrate on which a heat sink is assembled is placed on the heat-resistant sheet in which a heat-resistant sheet is attached to the center hole of the metal frame to form a recess, and the mounting substrate and the metal frame are mounted by a mold. Since the sealing resin filled around the heat sink is blocked by the metal frame and sealed, the resin pressure can be evenly distributed.
In addition, a dam portion protrudes from one clamp surface of the mold, and when the mold die clamps the metal frame and the mounting substrate, the dam portion covered with the heat-resistant sheet contacts the side surface of the substrate. Therefore, the sealing resin does not leak to the outside from the substrate surface, and the yield is improved by suppressing the resin usage fee.

Preferred embodiments of a semiconductor mounting substrate and a method for manufacturing the same according to the present invention will be described below in detail with reference to the accompanying drawings.
First, the structure of a semiconductor mounting substrate will be described using a light emitting substrate on which a light emitting element is mounted as an example. In FIG. 1, a mounting substrate 1 is a known glass epoxy resin substrate, a wiring pattern is formed on a mounting surface 1a of a semiconductor device 2, and a semiconductor device (for example, an LED package) 2 is mounted on the substrate terminal. The LED package is a light emitting element in which an upper portion of a light emitting diode, which is an example of the semiconductor chip 27, is covered with a lens cap 28. In a high brightness LED, a large current flows and a large amount of heat is generated. In addition to the LED package, the semiconductor device 2 includes a high-power semiconductor element having an integrated circuit such as a CPU or MPU and generating a large amount of heat.

  In FIG. 1, a through-hole 3 is formed in a portion where a semiconductor device 2 is mounted on a mounting substrate 1. A flat plate-like shape that dissipates the heat generated by projecting the protrusion 4 into the through hole 3 on the opposite side of the mounting surface 1a of the semiconductor device 2 of the mounting substrate 1 directly or indirectly with the semiconductor device 2. A heat sink 5 is assembled.

The right half of FIG. 1 shows an example in which the semiconductor chip 27 of the semiconductor device 2 is directly mounted on the protrusion 4 of the heat sink 5 and electrically connected to the circuit wiring of the mounting substrate 1 and then the package outer shape is sealed with resin. Indicates. In the figure, the semiconductor chip 27 is directly mounted on the protrusion 4, but an elastomer or the like may be inserted.
The left half of FIG. 1 shows an example in which the outer shape of the package is sealed with resin after indirectly contacting the semiconductor device 2 and the heat sink 5 via a silicon heat transfer sheet 6 (insulating sheet). Although the silicon heat transfer sheet 6 is inserted between the protrusion 4 and the semiconductor device 2 in FIG. The heat sink 5 exposes the flat plate portion 5a, and the outer periphery is sealed with a sealing resin (for example, epoxy resin) 7 and is held integrally with the mounting substrate 1.

  The heat sink 5 may be provided with a heat radiating fin 8 provided in contact with the flat plate portion 5 a and a cooling fan 9 for forcibly cooling the heat radiating fin 8. The radiating fin 8 and the mounting block 26 can be mounted by an existing mounting method such as screwing or abutting with a spring or the like. This is because the heat dissipation efficiency is improved by cooling the heat sink 5. Further, the mounting block 26 that is one end of the heat pipe 10 may be connected to the flat plate portion 5 a of the heat sink 5, and the other end may be connected to the radiation fin 8.

2A is a perspective view of the mounting substrate 1 on which the heat sink 5 is assembled, and FIG. 2B is an exploded view thereof. FIG. 2C shows a cross-sectional view of the outer peripheral edge 5 b of the heat sink 5.
In FIG. 2C, it is desirable that the outer peripheral edge portion 5b of the heat sink 5 is formed with a drooping portion 5c or a chamfered portion 5d. This is because the sealing resin 7 can be filled on the surface side of the drooping portion 5c or the chamfered portion 5d to prevent the falling portion 5c or the chamfered portion 5d.

The heat sink 5 is provided singular or plural, the total area of the flat portion 5a to the heat mounting substrate 1 entirely generated in the semiconductor device 2 is formed to be equal properly and the area around the sealing resin 7 Heat is collected by the heat sink 5 without being diffused and can be efficiently radiated. For example, the linear expansion coefficients of the substrate component, the mounting substrate 1, the heat sink 5, and the sealing resin 7 that were tested are: glass epoxy substrate; 14 to 15 ppm / ° C., heat sink (pure copper; C1020); 17 ppm / ° C., epoxy Resin; 8 to 16 ppm / ° C. The material of the heat sink 5 is not only a metal material having good thermal conductivity such as pure copper, copper alloy, aluminum, but also a resin material having high heat resistance such as engineering plastic in which carbon is mixed into PPS (polyphenylene sulfite). .

  Further, the number of the through holes 3 provided in the substrate 1 and the number of the protrusions 4 provided in the heat sink 5 may be one or a plurality. In this embodiment, the semiconductor device 2 is provided so as to come into contact with the semiconductor device 2 in consideration of the heat conduction efficiency and the substrate space.

Next, an example of a method for manufacturing a semiconductor mounting substrate will be described with reference to FIGS. 3 to 6 illustrate a method for manufacturing a semiconductor mounting substrate by compression molding, and FIG. 7 illustrates a method for manufacturing a semiconductor mounting substrate by transfer molding.
First, in FIG. 3A, the mold 12 can be configured by using, for example, a resin sealing press device and a mold as shown in FIG. 1 of Japanese Patent Laid-Open No. 2001-176902. For example, the upper die 15 is suspended from an upper die base (not shown) by a spring. In the above publication, the upper die 15 is suspended by a spring, but the spring may not be provided. The upper die 15 and the lower die 16 are provided with heaters (not shown). The upper mold clamping surface 15 a of the mold 12 is covered with a heat resistant sheet (for example, a release film, a UV curable film, etc.) 13.

  A heat resistant sheet 13 is attached to the lower surface of the metal frame 14 so as to close the center hole 14a. The central hole 14 a of the metal frame 14 is a through hole having an outer shape that can accommodate the mounting substrate 1. The mounting board 1 on which the heat sink 5 is assembled is placed with the mounting surface 1a facing down on the heat-resistant sheet 13 in which the central hole 14a of the metal frame 14 is closed with the heat-resistant sheet 13 and the recess 14b is formed. The The heat sink 5 is assembled by fitting the protrusions 4 into the through holes 3 from the surface (heat radiating surface) 1b opposite to the mounting surface 1a of the mounting substrate 1 (see FIGS. 4A and 4B).

  Next, the metal frame 14 on which the mounting substrate 1 is placed and the sealing resin 7 are carried into the lower mold clamping surface 16a of the mold 12 in which the mold is opened. For example, a sealing resin (liquid resin, granular resin, etc.) 7 is supplied to the substrate surface around the heat sink 5 assembled to the mounting substrate 1, and the mold 12 is closed to mount the mounting substrate 1 and the metal frame. 14 is clamped. At this time, the molten sealing resin 7 is filled in the gap around the heat sink 5 while being heated and pressurized and cured (curing). Since the sealing resin 7 does not leak outside the concave portion 14b of the metal frame 14, it can be sealed by applying a sufficient resin pressure. Furthermore, a known air vent may be provided on the metal frame 14.

4 (a) and 4 (b), the heat sink 5 may be mounted after the mounting substrate 1 is mounted on the long heat-resistant sheet 13 that covers the upper clamp surface 15a. good.
Further, before the metal frame 14 is carried into the mold 12, the sealing resin (liquid resin, granular resin, etc.) 7 is supplied to the substrate surface around the heat sink 5 assembled to the mounting substrate 1. The metal frame 14 may be carried into the mold 12. Moreover, the heat-resistant sheet 13 or the release film may be inserted also on the upper surface of the heat sink 5 to be resin-sealed.

  Alternatively, in FIG. 3B, a dam portion 17 protrudes from the upper mold clamping surface 15 a, and when the mold 12 is clamped, the dam portion 17 covers the side surface of the substrate with the heat resistant sheet 13. May be. The dam portion 17 enters the center hole 14 a between the outer peripheral surface of the substrate and the inner wall surface of the metal frame 14, contacts the lower mold clamping surface 16 a, and contacts the outer surface of the mounting substrate 1. . When the mold 12 is clamped, the melted sealing resin 7 is filled in the gap around the heat sink 5 (in the center hole 14a) and is damped by the dam portion 17 and cured by heating with the resin pressure applied (cure) ).

  FIG. 5 shows a molded product surrounded by the metal frame 14 after resin sealing. 5A is a plan view of a molded product surrounded by the metal frame 14, FIG. 5B is a side sectional view thereof, and FIG. 5C is a side sectional view of a mounting substrate portion. When the mold 12 is opened and the metal frame 14 is taken out, the molded product 18 including the mounting substrate 1 can be taken out. Further, the molded product 18 surrounded by the metal frame 14 can be easily separated by pressing. Further, since the heat-resistant sheet 13 has few contact surfaces with the sealing resin 7, it can be easily peeled off from the molded product 18.

  In FIG. 6, a plurality of heat sinks 5 provided may be connected by a connecting member 11 that easily conducts heat and sealed with resin. In this case, heat dissipation can be enhanced by using all of the heat sink 5 provided on the mounting substrate 1.

Next, a method for manufacturing a semiconductor mounting substrate using transfer molding will be described with reference to FIG. 7A is a plan view of the mold, FIG. 7B is a sectional view thereof, and FIG. 7C is a side sectional view of the molded product.
In FIG. 7B, a mold cull 21 and a mold runner gate 22 are formed in the upper mold 20 of the mold mold 19. The lower mold 23 is provided with a pot 24 and a plunger 25. The metal frame 14 on which the mounting substrate 1 to which the heat sink 5 is assembled is placed with the mounting surface facing downward is carried into the mold 19. The mounting substrate 1 is placed on the heat-resistant sheet 13 in which the central hole 14a of the metal frame 14 is closed and the heat-resistant sheet 13 is attached to form a recess 14b. The heat-resistant sheet 13 may be inserted so as to cover the clamp surface of the upper mold 20.

The pot 24 of the mold 19 is filled with a resin tablet (which may be a granular resin or a liquid resin).
Next, the mold 19 is closed to clamp the metal frame 14 and the work (heat sink 5 and mounting substrate 1). Then, the sealing resin 7 heated and melted by moving the plunger 25 upward is filled into the gap around the heat sink 5 through the mold cull 21 and the mold runner gate 22. The sealing resin 7 is dammed to the metal frame 14 and is cured by heating with the resin pressure applied (cure; see FIG. 7A).

  A dam portion 17 similar to that shown in FIG. 3B may project from the clamp surface of the upper mold 20. The dam portion 17 is preferably covered with a heat resistant sheet 13. When the mold 19 is clamped, the dam portion 17 enters the center hole 14a between the outer peripheral surface of the substrate and the inner wall surface of the metal frame 14 and comes into contact with the lower mold clamping surface 16a. Abut so as to surround. Thereby, the resin usage fee can be reduced.

  Finally, in FIG. 7C, if the mold 19 is opened and the metal frame 14 is taken out, the molded product 18 can be taken out. Further, the molded product 18 surrounded by the metal frame 14 can be easily separated by pressing. Further, since the heat-resistant sheet 13 has few contact surfaces with the sealing resin 7, it can be easily peeled off from the molded product 18.

  The heat-resistant sheet 13 covers a portion that comes into contact with the sealing resin. In this embodiment, the heat-resistant sheet 13 is sucked and stretched on the molding die clamping surface. When a release film is used as an example of the heat-resistant sheet 13, it has heat resistance that can withstand the heating temperature of the mold, and is easily peeled off from the upper mold surface, and has flexibility and extensibility. Materials such as PTFE, ETFE, PET, FEP, fluorine-impregnated glass cloth, polypropylene, and polyvinylidene chloride are preferably used. When using a UV curable sheet, the heat resistant sheet 13 is peeled off by irradiating with UV light.

A process of manufacturing the light emitting substrate shown in FIG. 1 after assembling the heat sink 5 to the mounting substrate 1 by compression molding or transfer molding as described above will be described.
When the light emitting substrate shown in the right half of FIG. 1 is manufactured, a semiconductor chip (light emitting diode) 27 is die-bonded to the protrusion 4 exposed to the substrate mounting surface 1a, and the semiconductor chip 27 and the substrate terminal portion are connected to, for example, a wire. Electrical connection by bonding. When the semiconductor chip 27 is resin-sealed by a known molding method and the lens cap 28 is attached, the light emitting substrate is assembled.

  1 is manufactured, the heat transfer sheet 6 is attached to the protrusion 4 exposed on the mounting surface 1a of the mounting substrate 1. After that, when the semiconductor device (light emitting diode) 2 is mounted on the substrate via the heat transfer sheet 6 and the lens cap 28 is attached, the light emitting substrate is assembled.

  As described above, various preferred embodiments of the present invention have been described. However, the molding method is not limited to the compression molding and transfer molding described above, and for example, injection molding may be used. Further, although the light emitting device on which the LED is mounted is illustrated, the light emitting device may be used for a mounting substrate of another high heat generation semiconductor device such as a CPU. In addition, the light-emitting device can be used in a wide range of applications such as a lighting device, a backlight, or a light source substrate for a vehicle in home appliances.

It is explanatory drawing of the light-emitting device using a semiconductor mounting board. FIG. 4 is a semiconductor mounting substrate, an exploded perspective view thereof, and a partial cross-sectional view of the heat sink mounted on the substrate. It is sectional explanatory drawing of the mold metal mold | die by a compression molding method. It is a perspective view which shows the manufacturing process of a semiconductor mounting board | substrate. It is the top view and side sectional view of the molded product surrounded by the metal frame, and the side sectional view of the molded product. It is a top view of the molded product which concerns on another example. It is a top view of a mold metallic mold by transfer molding, a sectional view, and a side sectional view of a molded product.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 1a Mounting surface 1b Heat radiation surface 2 Semiconductor device 3 Through-hole 4 Projection part 5 Heat sink 5a Flat plate part 5b Outer peripheral edge part 5c Dripping part 5d Chamfer part 6 Silicon heat transfer sheet 7 Sealing resin 8 Radiation fin 9 Cooling fan 10 Heat pipe DESCRIPTION OF SYMBOLS 11 Connection member 12,19 Mold die 13 Heat resistant sheet 14 Metal frame 14a Center hole 14b Recess 15,20 Upper mold 15a Upper clamp surface 16,23 Lower mold 16a Lower clamp surface 17 Dam part
18 Molded products
20 Mold Cull 21 Mold Runner Gate
24 pots
25 Plunger
26 Mounting Block 27 Semiconductor Chip 28 Lens Cap

Claims (5)

A mounting substrate in which a through hole smaller than the mounting area of the semiconductor device is formed in a portion where the semiconductor device is mounted;
A protrusion is fitted into the through-hole on the side opposite to the semiconductor device mounting surface of the mounting substrate, and is assembled so as to be able to contact the semiconductor device directly or indirectly, and a drooping portion or a chamfered portion is formed at the outer peripheral edge portion. And a heat sink having a flat plate portion larger than the mounting area of the semiconductor device ,
The heat sink is held retained the sealed around the sealing resin exposed flat portion on the substrate surface opposite to fill the sagging portion or the sealing resin on the surface side of the chamfered portion integrally with the substrate Semiconductor mounting board.   The semiconductor mounting substrate according to claim 1, wherein one or a plurality of the heat sinks are provided, and the total area of the flat plate portions is equal to the area of the surrounding sealing resin.   The semiconductor mounting substrate according to claim 1, wherein the heat sink is connected to the heat radiating fins through heat radiating fins attached to the flat plate portion or heat pipes connected to the flat plate portion. A step of closing the central hole on one surface of the metal frame and attaching a heat-resistant sheet;
A mounting in which a through hole is formed at a mounting position where a semiconductor device is mounted on a heat-resistant sheet in which a recess is formed by closing the central hole of the metal frame, and a heat sink is assembled by fitting a protrusion into the through hole Placing the substrate with the mounting surface facing down;
Carrying the metal frame and the sealing resin into a mold or supplying the sealing resin onto a mounting substrate around the heat sink and then carrying the metal frame into the mold;
Clamping the mounting substrate and the metal frame with the mold, and filling and curing the sealing resin in the gap around the heat sink while heating and pressing; and
A method for manufacturing a semiconductor mounting board including:   A dam part protrudes from one clamping surface of the mold, and when the mold mold clamps the metal frame and the mounting board, the dam part covered with the heat-resistant sheet contacts the side surface of the board. Item 5. A method for manufacturing a semiconductor mounting substrate according to Item 4.

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