JP7675665B2 - Semiconductor device manufacturing apparatus and semiconductor device manufacturing method - Google Patents

Description

This disclosure relates to the manufacture of semiconductor devices.

The semiconductor device described in Patent Document 1 is configured to include a lead frame, a control semiconductor element (IC) and a power semiconductor element bonded to the lead frame by a bonding material, and an insulating resin that seals them. Such a semiconductor device is manufactured, for example, by using different bonding materials under the control semiconductor element and under the power semiconductor element, and bonding the control semiconductor element to the lead frame and then bonding the power semiconductor element to the lead frame.

JP 2011-29492 A

In conventional technology, when joining a control semiconductor element to a lead frame, the entire lead frame is heated, which creates the problem of oxidizing the entire lead frame, including the parts to which the control semiconductor element is not joined.

This disclosure has been made to solve the above problems, and aims to suppress oxidation of the entire lead frame when joining a control semiconductor element to the lead frame.

The semiconductor device manufacturing apparatus of the present disclosure includes a housing that stores multiple workpieces that are in-process semiconductor devices, and multiple heater plates arranged within the housing, each workpiece including a lead frame and a control semiconductor element mounted on a first region of the lead frame via a thermosetting resin, and each heater plate contacts only the first region of the lead frame in each workpiece stored in the housing.

According to the semiconductor device manufacturing apparatus of the present disclosure, each heater plate heats only the portion of the lead frame on which the control semiconductor element is mounted in each workpiece, and the control semiconductor element is bonded to the lead frame. At this time, the portion of the lead frame on which the control semiconductor element is not mounted is not heated, so oxidation is suppressed.

1 is a cross-sectional view of a semiconductor device according to a first embodiment; 2 is a flowchart showing a method for manufacturing the semiconductor device according to the first embodiment. 2 is a side view of a work before a thermosetting resin is applied in a manufacturing method of a semiconductor device according to a first embodiment; FIG. 4 is a side view showing a state in which a thermosetting resin is applied to a workpiece in the manufacturing method of a semiconductor device according to the first embodiment; FIG. 4 is a side view showing a state in which a control semiconductor element is joined to a workpiece by a thermosetting resin in the manufacturing method of a semiconductor device according to the first embodiment; FIG. FIG. 2 is a perspective view showing a housing that houses a plurality of workpieces.

<A. First embodiment>
<A-1. Configuration>
1 is a cross-sectional view of a semiconductor device 101 according to embodiment 1. The semiconductor device 101 includes a lead frame 1, a control semiconductor element (IC) 3, power semiconductor elements 5 and 6, metal wires 7, and a mold resin 8.

The lead frame 1 is conductive, for example copper. The lead frame 1 includes a number of leads 11 and 12.

The lead 11 has an element mounting portion 111, a wire wiring portion 112, and a terminal portion 113. A control semiconductor element 3 is bonded to the element mounting portion 111 of the lead 11 by a thermosetting resin 2. The element mounting portion 111 of the lead 11 is also referred to as the first region.

The lead 12 has an element mounting portion 121, a wire wiring portion 122, and a terminal portion 123. A plurality of power semiconductor elements 5, 6 are joined to the element mounting portion 121 of the lead 12 by solder 4.

Metal wires 7 are used to connect between the wire wiring portion 112 of the lead 11 and the control semiconductor element 3, between the control semiconductor element 3 and the power semiconductor element 6, between the power semiconductor elements 5 and 6, and between the power semiconductor element 5 and the wire wiring portion 122 of the lead 12. The metal wires 7 are, for example, Al wires.

The lead frame 1, the control semiconductor element 3, the power semiconductor elements 5 and 6, and the metal wires 7 are sealed with the molded resin 8, except for the terminals 113 and 123. The terminals 113 and 123 protrude from both sides of the molded resin 8 and are bent upward.

In FIG. 1, two power semiconductor elements 5 and 6 are mounted on the lead frame 1, but the number of power semiconductor elements mounted on the lead frame 1 may be one or three or more.

<A-2. Manufacturing method>
2 is a flowchart showing a method for manufacturing the semiconductor device 101 according to the first embodiment. The method for manufacturing the semiconductor device 101 will be described below with reference to FIG.

First, a thin sheet of a metal material such as copper is pressed into an appropriate shape to form the lead frame 1 (step S101). At this time, a step may be provided between the element mounting portion 111 and the wire wiring portion 112 in the lead 11, or a step may be provided between the element mounting portion 121 and the wire wiring portion 122 in the lead 12. The lead frame 1 may include multiple units of the same shape. If necessary, appropriate locations of the lead frame 1 may be silver-plated.

Figure 3 is a side view of the lead 11 of the lead frame 1 created in step S101. Figure 3 shows the lead 11 before the thermosetting resin 2 is applied.

Next, a thermosetting resin 2 is applied to the element mounting portion 111 of the lead 11, and the control semiconductor element 3 is mounted on the element mounting portion 111 via the thermosetting resin 2 (step S102).

Figures 4 and 5 show how the control semiconductor element 3 is mounted on the leads 11 using a typical resin die bonder. In Figure 4, the lead frame 1 including the leads 11 is transported to a resin dispensing area in room temperature air. Then, pressure is applied from a dispenser 21 to a syringe 22 containing the thermosetting resin 2, causing the thermosetting resin 2 to be applied onto the leads 11. The thermosetting resin 2 is, for example, a silver paste resin with a silver content of more than half.

Then, as shown in FIG. 5, the control semiconductor element 3 is mounted on the thermosetting resin 2. The control semiconductor element 3 is a chip that has been separated into individual pieces or a chip that has been diced on a wafer. The control semiconductor element 3 may be mounted on the leads 11 manually, or a general resin die bond may be used. At this point, the thermosetting resin 2 is uncured.

Next, the thermosetting resin 2 is thermally cured by the heating device 30 to bond the control semiconductor element 3 and the lead 11 (step S103).

Figure 6 is a perspective view of the heating device 30. The heating device 30 is configured with a housing 31 and a plurality of heater plates 32 provided within the housing 31.

The housing 31 is a rectangular parallelepiped with one open side, and its vertical dimension is greater than its horizontal dimension. The housing 31 is composed of a right side member 311, a left side member 312, an upper member 313, a lower member 314, and a rear member 315. There is no member on the front side of the housing 31 that faces the rear member 315. In other words, the front side of the housing 31 is an opening, and the work 10 can be inserted and removed from the housing 31 through this opening. Here, the work 10 is a work in progress of the semiconductor device 101, and is the lead frame 1 on which the control semiconductor element 3 is mounted.

The housing 31 can store multiple workpieces 10 in the vertical direction. In other words, the housing 31 has multiple workpiece storage sections that store multiple workpieces 10. The multiple workpieces 10 stored in each workpiece storage section are arranged vertically inside the housing 31. The vertical direction is the up-down direction on the paper surface of FIG. 6, and is the direction perpendicular to the upper surface member 313 and the lower surface member 314 of the housing 31.

Therefore, multiple heater plates 32 for heating each workpiece 10 are also arranged vertically within the housing 31. For example, five or more heater plates 32 are arranged within the housing 31. In the example of FIG. 6, six heater plates 32 are arranged within the housing 31.

Although not shown in FIG. 6, the right side member 311 and the left side member 312 of the housing 31 are provided with protrusions that protrude into the housing 31, and these protrusions form a work storage section. The work 10 is placed on these protrusions, and its position within the housing 31 is fixed. Protrusions for mounting the work 10 may be provided on the back member 315 in addition to the right side member 311 and the left side member 312 of the housing 31.

The heater plates 32 are arranged at positions corresponding to each work storage section in the housing 31. That is, each heater plate 32 is arranged at a position where it contacts each work 10 stored in the housing 31 from below.

In addition, each heater plate 32 does not contact the entirety of each workpiece 10, but only contacts the portion of each workpiece 10 on which the control semiconductor element 3 is mounted. Therefore, each heater plate 32 heats only the first region of each workpiece 10, i.e., the portion on which the control semiconductor element 3 is mounted.

The above describes the protrusions provided on the right side member 311 and the left side member 312 of the housing 31. However, the right side member 311 and the left side member 312 on which the heater plate 32 is provided may not have any protrusions, and the workpiece 10 may be mounted directly on the heater plate 32. In this case, the heater plate 32 may be fixed to the right side member 311 or the left side member 312 of the housing 31, and may further be fixed to the back member 315.

The melting point of the thermosetting resin 2 is assumed to be 140°C, so the heat resistance temperature of the housing 31 is set to 150°C or higher. The housing 31 is made of, for example, stainless copper.

A workpiece holder may be provided inside the housing 31 to press the workpiece 10 vertically against the heater plate 32. This allows the workpiece 10 stored inside the housing 31 to be reliably in contact with the heater plate 32. The workpiece holder may be configured to press the workpiece 10 by its own weight, or may be configured to press the workpiece 10 by the elastic force of a spring.

In FIG. 6, the multiple heater plates 32 are arranged parallel to each other within the housing 31. In addition, the multiple workpieces 10 stored within the housing 31 are parallel to each other and to the multiple heater plates 32.

In FIG. 6, the area of each heater plate 32 in a plan view is smaller than the area of the upper surface member 313 or the lower surface member 314 of the housing 31. Here, a plan view means a view from a direction perpendicular to the upper surface member 313 or the lower surface member 314.

The dimensions of the housing 31 in a plan view may be slightly larger than the dimensions of the workpiece 10 in a plan view. In other words, the dimensions of the upper surface member 313 or the lower surface member 314 of the housing 31 may be approximately 1 cm larger than the dimensions of the workpiece 10 in both the vertical and horizontal directions.

The area of the heater plate 32 in a plan view is 2/3 or less, and more preferably 1/2 or less, of the area of the housing 31 in a plan view.

In step S103 in FIG. 2, the lead frame 1 on which the thermosetting resin 2 and the control semiconductor element 3 are mounted, i.e., the workpiece 10, is placed on the heater plate 32 in the housing 31 shown in FIG. 6. The workpiece 10 may be placed manually or by using a device.

Then, the temperature of the heater plate 32 is maintained at around 140°C for two hours to directly heat only the first region of the lead frame 1. This is also called the first heating. If there is concern that the first heating may cause oxidation of the first region, deteriorating the quality of the wire bond, the resin may be heated in an oxygen-reduced atmosphere using nitrogen (N2) gas.

Next, solder 4 is applied to the element mounting portion 121 of the lead 12, and the power semiconductor elements 5, 6 are joined onto the element mounting portion 121 via the solder 4 (step S104). The power semiconductor elements 5, 6 are individualized chips or chips diced onto a wafer. The power semiconductor elements 5, 6 are joined by heating the workpiece 10. This heating is also called second heating to distinguish it from the first heating when joining the control semiconductor element 3. The temperature of the second heating is set to around 270°C, and soldering is performed in an oxygen-reduced environment with a cooling mechanism installed.

The joining of the power semiconductor elements 5, 6 with the solder 4 can be performed simultaneously with the hardening of the thermosetting resin 2 using a heater plate 32 and a cooling plate (not shown) inside the housing 31, or a general solder die bonder can be used.

Next, taking into consideration the step between the power semiconductor elements 5, 6 and the wire wiring portion 122 of the lead 12, the two are bonded with Al wires (step S105). The diameter and number of Al wires are determined by the current flowing through the power semiconductor elements 5, 6. During Al wire bonding, the oxide film on the Al wire is removed by ultrasonic waves. Al wire bonding may be performed manually or using a general wire bonder.

Next, taking into consideration the step between the control semiconductor element 3 and the wire wiring portion 112 of the lead 11, the two are bonded with Au wire (step S106). The number of Au wires is determined by the current flowing through the control semiconductor element 3. The diameter of the Au wire is about 40 μm. The Au wire may be bonded by ultrasonic thermocompression while heating the lead frame 1. The Au wire bonding may be performed manually or by using a device. Also, Cu wire or Ag wire may be used instead of Au wire.

Next, the control semiconductor element 3 and power semiconductor elements 5 and 6 mounted on the lead frame 1, as well as the wire bond wiring, are sealed with molded resin 8 by transfer molding (step S107). The molded resin 8 is a thermosetting resin. First, the molded resin 8 is heated to about 175°C, and then heated at 170°C for about 10 hours as an after-cure, and hardened. Here, the heating device 30 used in the first heating in step S103 or the second heating in step S104 may be used by changing the vertical height of the heater plate 32 in the housing 31.

After that, unnecessary parts of the lead frame 1 and burrs and the like of the mold resin 8 are cut off (step S108). The unnecessary parts of the lead frame 1 are changed depending on the shape of the lead frame 1. This step may be performed manually or by using a device.

Next, plating is performed on the terminals 113 and 123 of the lead frame 1 (step S109). This step may be performed manually or using a device.

Then, the terminal portions 113, 123 of the lead frame 1 are bent into an appropriate shape (step S110).

Finally, the module is tested (step S111), and the semiconductor device 101 shown in FIG. 1 is completed.

<A-3. Effects>
The heating device 30, which is a manufacturing device for a semiconductor device according to the first embodiment, includes a housing 31 that houses a plurality of workpieces 10 that are in-process products of a semiconductor device 101, and a plurality of heater plates 32 arranged in the housing 31. Each workpiece 10 includes a lead frame 1 and a control semiconductor element 3 mounted via a thermosetting resin 2 on an element mounting portion 111 of a lead 11 that is a first region of the lead frame 1. Each heater plate 32 contacts only the element mounting portion 111 of each workpiece 10 housed in the housing 31. Therefore, according to the heating device 30, when joining the control semiconductor element 3 to the lead frame 1, only the element mounting portion 111, which is the portion of the lead frame 1 on which the control semiconductor element 3 is mounted, is heated, and the other portions are not heated, so that oxidation of the other portions is suppressed.

In addition, in the first embodiment, the housing 31 may be a rectangular parallelepiped whose vertical dimension is larger than its horizontal dimension and whose one side is open, and which stores a plurality of workpieces 10 arranged vertically. In a plan view from the vertical direction, the area of each heater plate 32 may be 2/3 or less of the area of the housing 31. With this configuration, the heating device 30 can process a plurality of workpieces 10 collectively, and since only the element mounting portion 111 of each workpiece 10 is heated by each heater plate 32, oxidation of parts other than the element mounting portion 111 of the lead frame 1 is suppressed.

In addition, in the first embodiment, each heater plate 32 may be fixed to a side member that contacts the opening of the housing 31 or a back member that faces the opening. With this configuration, the workpiece 10 can be mounted on the heater plate 32, so there is no need to provide a protrusion on the side member of the housing 31 in order to mount the workpiece 10.

The manufacturing method of the semiconductor device according to the first embodiment involves preparing at least one work 10 including a lead frame 1 and a control semiconductor element 3 mounted via a thermosetting resin 2 on an element mounting portion 111, which is a first region of the lead frame 1, and heating only the element mounting portion 111 of the at least one work 10 as a first heating. Therefore, when the control semiconductor element 3 is bonded to the lead frame 1, oxidation of the portions of the lead frame 1 other than the element mounting portion 111 is suppressed.

The embodiments can be freely combined, modified, or omitted as appropriate.

1 Lead frame, 2 Thermosetting resin, 3 Control semiconductor element, 4 Solder, 5, 6 Power semiconductor element, 7 Metal wire, 8 Molding resin, 10 Work, 11, 12 Lead, 21 Dispenser, 22 Syringe, 30 Heating device, 31 Housing, 32 Heater plate, 101 Semiconductor device, 111, 121 Element mounting portion, 112, 122 Wire wiring portion, 113, 123 Terminal portion, 311 Right side member, 312 Left side member, 313 Top member, 314 Bottom member, 315 Back member.

Claims (10)

a housing for housing a plurality of workpieces which are in-process semiconductor devices;
a plurality of heater plates disposed within the housing;
Each of the workpieces is
A lead frame;
a control semiconductor element mounted on the first region of the lead frame via a thermosetting resin;
each of the heater plates contacts only the first region of the lead frame in each of the workpieces housed in the housing;
Manufacturing equipment for semiconductor devices. The housing is a rectangular parallelepiped having a larger vertical dimension than a horizontal dimension and one side open, and stores the plurality of workpieces arranged in the vertical direction;
When viewed in a plan view from the vertical direction, the area of each of the heater plates is ⅔ or less of the area of the housing.
2. The apparatus for manufacturing a semiconductor device according to claim 1. Each of the heater plates is fixed to a side member in contact with the opening of the housing or a back member facing the opening.
3. The apparatus for manufacturing a semiconductor device according to claim 2. The heat resistance temperature of the housing is 150° C. or higher.
The manufacturing apparatus for a semiconductor device according to any one of claims 1 to 3. Further comprising a workpiece holder for pressing each of the workpieces stored in the housing against each of the heater plates.
5. The manufacturing apparatus for a semiconductor device according to claim 1. preparing at least one workpiece including a lead frame and a control semiconductor element mounted on a first region of the lead frame via a thermosetting resin;
heating only the first region of the lead frame in the at least one workpiece as a first heating;
A method for manufacturing a semiconductor device. The first heating is performed by at least one heater plate disposed under the first region of the at least one workpiece.
The method for manufacturing a semiconductor device according to claim 6 . the at least one workpiece is a plurality of workpieces;
the at least one heater plate is a plurality of heater plates;
In the first heating, each of the workpieces is heated simultaneously by each of the heater plates.
The method for manufacturing a semiconductor device according to claim 7 . The first heating is performed by arranging the plurality of workpieces in one direction and storing them in a housing, and by using the plurality of heater plates arranged in the housing.
The method for manufacturing a semiconductor device according to claim 8 . After the first heating, at least one power semiconductor element is mounted on a second region of the lead frame that is different from the first region, via a bonding material different from the thermosetting resin, and the at least one workpiece on which the at least one power semiconductor element is mounted is heated as a second heating at a temperature higher than that of the first heating.
The method for manufacturing a semiconductor device according to any one of claims 6 to 9.

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