JPH0713984B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a power semiconductor device having a composite element in which a control element and a power element are combined.

<Prior Art> Conventionally, a power semiconductor device having a composite element in which a semiconductor control element including an integrated circuit (hereinafter referred to as an IC) and a semiconductor power element are combined has a control element 2 on a substrate 1 as shown in FIG.
And power device (heat spreader 3, power chip 4)
And a composite element that is a combination of the above and a transfer element, powder coating, casting method or potting method, and these are used to provide a high thermal conductivity insulation seal containing a heat conductive medium (filler) 6 such as silica and alumina. By injecting a stopper material (epoxy resin) 5, the material is insulated and sealed.

In the figure, 7 is a bonding wire such as an aluminum wire, 8 is a semiconductor passive element, and 9 is a lead terminal. <Problems to be solved by the invention> However, a control element including such an IC and a power element There are transfer mold, powder coating, casting method, and potting method as the insulation sealing method of the power semiconductor device having the composite element in which the power element heat dissipation is the main focus. , High thermal conductivity epoxy resin is used.

Here, in the transfer mold and powder coating, the gelation time is very short, and therefore, after the resin is cured, the heat conduction medium is evenly distributed throughout the resin as shown in FIG. 3, and the heat conductivity becomes uniform. . In this case, the allowable junction temperature between the control element including the IC and the power element is lower in the control element, and the operating temperature range of the semiconductor device, which is a composite element, is restricted on the control element side.

Further, when the material is sealed with a material having uniform heat conduction, the allowable junction temperature of the power element becomes equal to the allowable junction temperature of the control element, and the operating temperature range of the semiconductor device is narrowed.

As a means corresponding to the above, when a composite element combining a control element and a power element is integrally sealed with an insulating sealing material by a casting method or a potting method, the insulating sealing material is provided around the power element. There is also a proposal of a method of forming a high heat conduction part and a low heat conduction part around the control element.

However, also in this method, the insulating encapsulant contains a heat conductive medium such as silica and alumina, and an epoxy resin having a long gelation time is used or an epoxy resin containing no heat conductive medium is used in combination. It is necessary and the number of processes increases.

Therefore, in view of the above problems, the present invention is a method for manufacturing a semiconductor device, which can effectively perform heat separation between a power element (high heat conduction section) and a control element (low heat conduction section) in one step, and can be used in a wide temperature range. For the purpose of providing.

<Means for Solving the Problems> The means for solving the problems according to the present invention is as shown in FIGS.
In the method for manufacturing a semiconductor device, which mounts a composite element in which the control element 12 and the power elements 13 and 14 are combined on the above, and integrally seals these with the insulating encapsulant 15 containing the heat conductive medium 16, By continuously stirring the insulating encapsulant 15 at a high temperature as a pretreatment before the casting operation of the encapsulant 15, and keeping the insulating encapsulant 15 at a high temperature even during the casting operation to reduce its viscosity. The sedimentation velocity of the heat transfer medium 16 is increased, and the power elements 13,1
A high heat conductive portion 17 is formed around the periphery of the control element 4 and a low heat conductive portion 18 is formed around the control element 12 to separate the high heat conductive portion 17 and the low heat conductive portion 18 into two layers.

<Operation> In the above means for solving problems, the insulating sealing material 15 is continuously stirred at a high temperature as a pretreatment before the casting operation of the insulating sealing material 15,
Even during the casting operation, the insulating sealing material 15 is kept at a high temperature and its viscosity is lowered to increase the sedimentation speed of the heat conduction medium 16, so that the high heat for sealing the power elements 13 and 14 in one step is used. Conducting part 17 and low heat conducting part 18 for sealing the control element 12
The heat separation with can be effectively performed.

Further, this makes it possible to provide a thermal odor in the same package, and the heat generated by the electronic elements 13 and 14 is controlled by the control element 1.
2 is difficult to transmit, and the setting of the operating temperature range of the semiconductor device can be used within the allowable junction temperature range on the electronic element 13, 14 side, so that a semiconductor device having a wide operating temperature range can be provided.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to FIG.
FIG. 1 is a cross-sectional view of a semiconductor device insulation-sealed by the potting method showing an embodiment of the present invention.

As shown in the figure, the semiconductor device of the present embodiment has a composite element in which a control element 12 including an IC and a power element (heat spreader 13, power chip 14) are combined on a substrate 11,
The composite element is integrally sealed by an potting method with an insulating sealing material 15 containing a heat conductive medium (filler) 16,
A high heat conduction part 17 in which a heat conduction medium 16 is aggregated around the power elements 13 and 14, and a low heat conduction part 18 in which the heat conduction medium 16 is hardly distributed are formed around the control element 12.

The control element 12 is mounted on one side of the substrate 11,
At both ends of the control element 12, a semiconductor passive element 20 (for example,
Capacitors, resistors, etc.) are placed so as to face each other.

The power elements 13 and 14 are mounted on the other side of the substrate 11. The power chip 14 is mounted on the heat spreader 13 and is connected to the substrate 11 from the upper surface thereof by a bonding wire 21 such as an aluminum wire.

A lead terminal 22 is attached to one side of the substrate 11, and a part of the lead terminal 22 projects from the insulating encapsulant 15.

The insulating sealing material 15 is a thermosetting type two-component mixed epoxy resin containing ultrafine silica and alumina in order to prevent the heat conducting medium 16 from settling. The control element 12 and the power elements 13 and 14 are formed in a box shape (package) so as to be integrated.

Next, a method of manufacturing the semiconductor device will be described.

First, since the heat generation amount of the power elements 13 and 14 is high,
14 is mounted on the substrate 11 at a position away from the lead terminals 22, and the heat generation amount of the control element 12 is lower than that of the power elements 13 and 14,
The control element 12 is mounted on the lead terminal 22 side. Then, the lead terminal 22 is placed on the upper side, and the insulating sealing material 15 containing the heat conductive medium 16 is used to perform the insulating sealing by the potting method.

The insulating sealing material 15 used at this time is a two-liquid mixed thermosetting type epoxy resin in which the main agent and the curing agent are separately provided, and the heat conduction medium 16 is contained in each of the main agent and the curing agent. Then, the main agent and the curing agent are separately separated from each other at a temperature (for example, 80
Left for 1 hour. Next, the main agent and the curing agent are transferred to separate stirring stainless steel containers kept at 60 ° C. and continuously stirred. While continuing this agitation, on the other hand, the amount necessary for the injection filling of one semiconductor device is taken out, the main agent and the curing agent are mixed, and the mixture is injected into the box (case) 23. At this time, the box 23 is also heated and kept at 40 to 60 ° C. After injection,
The epoxy resin is heated and cured at a predetermined curing temperature.

By doing so, the heat transfer medium 16 can be settled under the epoxy layer within a predetermined time condition for the epoxy resin, and the high heat transfer part 17 can be provided around the power elements 13 and 14.
In addition, it is possible to form two layers of the low thermal conductive portion 18 around the control element 12 in one step.

Here, sedimentation of the heat transfer medium 16 will be described.

Liquid epoxy resin is a non-Newtonian fluid, but it is considered that Stokes' law for Newtonian fluid can be applied when the viscosity is lowered at high temperature. That is, the sedimentation velocity is directly proportional to the square of the particle radius of the heat transfer medium 16, proportional to the density difference between the particles and the liquid, and inversely proportional to the viscosity of the liquid.

Therefore, if the temperature of the resin is raised to lower the viscosity, the sedimentation of the heat transfer medium 16 increases.

Further, the epoxy resin contains ultrafine silica in order to prevent sedimentation of the heat transfer medium 16. This ultrafine silica has many Si-OH groups and forms hydrogen bonds with silanol groups to form a three-dimensional network structure, which is a heat transfer medium.
Prevents sedimentation of 16. Therefore, by continuously stirring the insulating sealing material 15 at a high temperature, the three-dimensional mesh structure is divided and the heat transfer medium 16 is easily settled.

As described above, in the same package in which the components are integrated, the insulating sealing material 15 is continuously stirred at a high temperature as a pretreatment before the casting operation of the insulating sealing material 15, and in the middle of the casting operation. Since the insulating sealing material 15 is kept at a high temperature and its viscosity is lowered to increase the sedimentation speed of the heat conducting medium 16, the high heat conducting portion 17 that seals the power elements 13 and 14 in one step.
And the low heat conductive portion 18 that seals the control element 12 can be effectively thermally separated.

Further, this makes it possible to provide a thermal odor in the same package, and the heat generated by the electronic elements 13 and 14 is controlled by the control element 1.
2 is difficult to transmit, and the setting of the operating temperature range of the semiconductor device can be used within the allowable junction temperature range on the side of the power elements 13 and 14, so that a semiconductor device having a wide operating temperature range can be provided.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, since the density distribution of the heat conductive medium can be changed by adjusting the initial heating rate of the epoxy resin and the heat retention temperature at the time of mixing, it is possible to create the optimum insulating seal for the allowable temperature of the built-in semiconductor element. it can.

Although the potting method has been described in the above embodiment, the casting method can also obtain the same effect as shown in FIG.

<Effects of the Invention> As is apparent from the above description, according to the present invention, the insulating sealing material is continuously stirred at a high temperature as a pretreatment before the casting operation of the insulating sealing material, and even during the casting operation. By keeping the insulating encapsulant at a high temperature and decreasing its viscosity, the sedimentation speed of the heat-conducting medium is increased. The heat separation from the conductive portion can be effectively performed.

Further, this makes it possible to have a thermal gradient in the same package, and it becomes difficult for the heat generated by the electronic element to be transmitted to the control element, and the setting of the operating temperature range for the semiconductor device is set to the allowable junction temperature on the power element side. Since it can be used within the range, it is possible to provide a semiconductor device having a wide operating temperature range.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device which is insulation-sealed by a potting method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a semiconductor device which is insulation-sealed by a casting method according to another embodiment of the present invention. FIG. 3 is a sectional view of a semiconductor device, and FIG. 3 is a sectional view of a conventional semiconductor device. 11: Substrate, 12: Control element, 13, 14: Power element, 15: Insulation sealing material, 16: Thermal conductive medium (filler), 17: High thermal conductive part, 18:
Low heat conduction part.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 23/31 25/04 25/16 A 25/18

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: mounting a composite element, which is a combination of a control element and a power element, on a substrate; and integrally sealing these elements with an insulating encapsulant containing a heat transfer medium. As a pretreatment before casting the sealing material, the insulating sealing material is continuously stirred at a high temperature, and the insulating sealing material is kept at a high temperature even during the casting operation to reduce the viscosity of the insulating material and thereby achieve a heat transfer medium. The high settling velocity of the power element is increased to form a high heat conductive part around the power element and a low heat conductive part around the control element to separate the high heat conductive part and the low heat conductive part into two layers. Manufacturing method of semiconductor device.