JPH011266A - semiconductor equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin-sealed semiconductor device, and particularly to a semiconductor device structure suitable for preventing resin cracking of the device during a reflow process.

[Conventional technology]

Regarding conventional semiconductor devices, Japanese Patent Application Laid-Open No. 57-17275
As described in Publication No. 6, in order to improve the adhesion between the semiconductor element and the element mounting frame and the bonding between the bonding wire and the external leads, precious metals are applied to the element mounting surface of the element mounting frame and the wire joints of the external leads. Coating (mainly gold (
, Au ) or silver (Ag)), but since the adhesion between the noble metal coating and the sealing resin is poor, the area where the coating is provided is used to improve the moisture resistance and reliability of the device. It was limited to the area around the mounting frame.

On the other hand, when a semiconductor device is soldered onto a printed circuit board or the like, the entire device is heated by infrared rays or fluorine-based inert liquid vapor in a reflow process.

At this time, the internal temperature of the device reaches a high temperature of 200°C or higher, and in resin-sealed semiconductor devices, moisture is present inside the device due to moisture absorption of the resin, and this moisture rapidly evaporates, resulting in several particles inside the device. Generates a vapor pressure of up to ten atmospheres. This vapor pressure generates stress inside the device, which causes cracks in the resin, whose strength drops significantly especially at product temperatures (>~150°C), and the cracks that occur inside the device penetrate to the surface of the device. It may pass. If such cracks occur, not only will L be damaged on the outside of the device, but moisture will easily infiltrate into the device, corroding the metal wiring on the semiconductor elements, and significantly reducing the moisture resistance reliability of the device. It will cause it to deteriorate. Prevent this kind of resin cracking.

For example, a structure described in Japanese Patent Application Laid-open No. 60-208846 has been proposed as a semiconductor device MLT structure that improves the reliability of the device. [Problems to be solved by the invention] In recent years, semiconductor devices During the flow process of soldering a semiconductor device to a substrate, the semiconductor device is exposed to infrared rays and fluorine-based inert liquid vapor, and the internal temperature of the device reaches a high temperature of 200° C. or more. Since the sealing resin has hygroscopic properties, the absorbed moisture within the device rapidly turns into water vapor at such high temperatures, generating an excessive vapor pressure of several tens of atmospheres inside the device. This vapor pressure generates stress inside the device, and cracks occur in the resin part, whose strength particularly decreases significantly at high temperatures.

In order to prevent such destruction of the device, it is necessary to quickly release the water vapor generated within the device.

In the above conventional technology, since the purpose is to increase the joint strength of the joints of each part of the device, the structure is such that it is difficult for water vapor generated inside the device to escape from the inside of the device, and if the device is exposed to high temperatures. No consideration has been given to preventing damage to the equipment.

On the other hand, in the semiconductor device structure example described above, the adhesiveness of the lead surface that supports the element mounting frame is reduced to facilitate the escape of generated steam. Methods for reducing the adhesiveness of the lead surface include rapidly cooling the device or oxidizing the surface. However, the method of rapidly cooling the device and peeling off the adhesive interface due to thermal stress generates large thermal stress in other parts of the device.
There is a risk that defects such as resin cracks may occur. Further, when the surface is oxidized, it is difficult to uniformly oxidize the entire surface, which causes unevenness on the surface. Since these irregularities serve as mechanical reinforcement for adhesion, they do not necessarily reduce the apparent contact force. As described above, the technology of the Congregation and Song Dynasty had a problem in that it was difficult to stably and uniformly reduce the adhesiveness of the lead surface that supported the element mounting frame.

The first object of the present invention is to prevent a semiconductor device from being destroyed at high temperatures and to improve the (g-axis properties) of the device.

The second object of the present invention is to stably and uniformly reduce the adhesiveness of the lead surface supporting the element mounting frame,
An object of the present invention is to provide a highly reliable semiconductor device by reliably releasing steam generated inside the device to the outside of the device.

[Means for solving problems]

The first object of the invention is to provide a lead apparatus f for supporting a semiconductor element mounting frame from a semiconductor element mounting frame to a semiconductor element mounting frame for applying a noble metal coating to a lead frame in a semiconductor device.
This can be achieved by providing it continuously up to the part that reaches the ff surface.

Further, the second object of the invention is achieved by providing in advance a coating having low adhesion to the sealing resin on the surface of the lead supporting the element mounting frame.

The present invention provides a semiconductor element, a tab on which the semiconductor element is mounted, a tab suspension lead formed integrally with the tab and supporting the tab, and a tab and tab suspension lead arranged separately from each other and the semiconductor element. A plurality of external leads electrically connected to the semiconductor element, a group of these leads, and a semiconductor element are sealed]
, and a resin. Application No. 1
In the semiconductor device, the entire surface of the tab and the tab suspension lead on the element mounting side and/or the entire surface of the opposite element mounting side is coated with a noble metal coating, and the surface of each external lead is coated with a noble metal coating. It is characterized by covering only the electrical connection side end with a precious metal coating.

Furthermore, the second invention of the present application is characterized in that the semiconductor device described above is characterized in that a noble metal-containing coating and/or a passivation-containing coating is formed on the entire front and back surfaces of the tab suspension lead. The plating film in this case is chromium (Cr).

Nickel (Ni), titanium (Ti), aluminum (A
Q), cobalt (Go), niobium (Nb), tantalum (
It is preferable to use a metal element such as Ta) or an alloy mainly composed of these elements, which forms a nonconductive film on the surface of the plating film. In particular, noble metals or alloys mainly composed of noble metals are preferred.

[Effect]

(Effects of the First Invention) Water vapor generated when a resin-sealed semiconductor device is exposed to high temperatures swells inside the semiconductor device and generates a pressure reaching several tens of atmospheres inside the semiconductor device. This causes cracks to occur in the resin, which has low strength. In conventional devices, a gold plating film was provided to ensure good bonding between the semiconductor element and the tab. However, because the adhesion of the gold plating film to the sealing resin is low, the area where the film is provided has been limited to the area around the tab (element mounting frame). For this reason, a tab suspension lead (a lead that supports the element mounting frame, but is not electrically connected to the element) and a seal 1):! Since the adhesive properties of the fat were good, there was no path for the water vapor generated inside to escape.

Therefore, when the first aspect of the present application adopts the configuration of the invention, water vapor generated inside the device at high temperature easily escapes to the outside of the device through this interface because the adhesiveness between the tab suspension lead and the sealing resin is low. Therefore, excessive vapor pressure is not generated within the device, and destruction of the device can be prevented. still,
At a low temperature near or below room temperature, the sealing resin contracts, so no gap is created at the adhesive interface between the tab suspension lead and the sealing resin. Therefore, under normal usage conditions,
Since it is possible to prevent moisture from entering from outside the device, even if the adhesiveness between the tab suspension lead and the resin is reduced, the moisture resistance reliability of the mounting part will not be impaired.

(Function of the second invention) In the same background as the first invention, if a coating that prevents or deteriorates the adhesion with the sealing resin is provided on the surface of the tab suspension lead in advance, the bonding with the resin of the tab is prevented. Peeling occurs at the interface between the tab hanging lead (coating) and the resin before the adhesive interface. Since the generated water vapor can escape to the outside of the device through this gap, excessive vapor pressure is not generated inside the device, and resin cracking can be prevented. Further, since there is no need to change the external shape of the semiconductor device at all, a conventional sealing mold can be used as is.

The coating material that deteriorates the adhesion between the resin and the lead frame material is a noble metal (gold (Au)) with an inert surface.
, 'E (Ag), Ruthenium (Ru).

Rhodium (Rh), Palladium (Pd), Osmium (
Os), iridium + platinum (Pi)), or metals that form a passive state on the surface (iron (Fe)).

Nickel (Ni), cobalt (Co), chromium (C, u
), titanium (Ti), niobium (Nb), tantalum (Ta
), aluminum (AQ)) or an alloy mainly composed of these may be used. As a method for attaching the film, a metal plating method or a thin film forming method (vapor deposition method, sputtering method, chemical vapor deposition method, etc.) may be used. If a film is to be provided, care must be taken to prevent the film from adhering by applying a protective film (mask) to areas other than the tab suspension leads in advance.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a resin-sealed semiconductor device according to an embodiment of the present invention. In this embodiment, a gold plating film is applied to the surfaces of the tab 4 and the tab suspension leads 3 provided at both ends thereof. FIG. 2 is a horizontal sectional view of the device taken along line A--A in FIG. The shaded area in the figure is the gold plating film 5 in Figure 1.
Indicates the area where the In addition, the tab hanging lead 3
A gold plating film 5 is provided on both the upper and lower surfaces. Since the gold plating film 5 has low adhesion to the sealing resin 1, peeling easily occurs at the adhesive interface. When a semiconductor device is exposed to high temperatures, water vapor generated inside the device tries to generate a large vapor pressure inside the device. Since the interface of the stopper resin 5 peels off when the pressure is small, water vapor can escape to the outside of the device through this interface.

On the other hand, near or below room temperature? ! ! The coefficient of linear expansion of the sealing resin is approximately 2 x 10-5/°C, and the coefficient of linear expansion of the iron-based lead frame is 5~].
10-6/℃, the resin shrinks and adheres to the lead frame while applying compressive force, which prevents moisture from entering from the outside. There's nothing to lose. Furthermore, code 2
is a semiconductor element, and 6 is an external lead.

In this example, since the water vapor generated inside the device at high temperatures can be easily released, the
! This has the effect of preventing damage to the RE and improving the reliability of the device.

For example, as shown in Figure 3, the water vapor generated when a resin-sealed semiconductor device is exposed to high temperatures swells inside the semiconductor device and generates a pressure of several tens of atmospheres inside. As shown, cracks 9 occur in the resin having low strength. In the conventional device, semiconductor cord 2 and tab l↓
A gold plating film 5 was provided to ensure good bonding, but because the adhesion between the gold plating film and the resin 1 was low, the area where the film was provided was limited to the area around the element mounting frame (tab) 4. . Therefore, since the adhesiveness between the leads (tab suspension leads) 3 supporting the element mounting frame and the sealing resin 1 was good, there was no path for the water vapor generated inside to escape. Therefore, as shown in FIG. 4 according to an embodiment of the present invention, a gold plating film 5 is continuously applied from the tab 4 to the area of the surface of the tab suspension lead 5 reaching the outside of the device. In this case, since the adhesion between the tab hanging lead 3 and the sealing resin 1 is low, the water vapor generated inside the device at high temperature easily escapes to the outside of the device through this interface, so there is no excess water vapor inside the device. This prevents the generation of excessive vapor pressure and prevents damage to the equipment. Note that at a low temperature near or below room temperature, the resin 1 contracts, so that no gap is created at the adhesive interface between the tab suspension lead 3 and the resin 1. Therefore, under normal usage conditions, it is possible to prevent moisture from entering from outside the device, so even if the adhesiveness between the tab suspension reed 3 and the resin 1 is reduced, the moisture resistance reliability of the device will not be impaired.

Next, a third embodiment of the present invention will be described using FIGS. 5 and 6. FIG. 5 is a horizontal sectional view of an example of the resin-to-IF type semiconductor device of the present invention. In this embodiment, tab suspension leads 3 are arranged at the four corners of the tab 4. Figure 6 is the 5th
Figure 3 shows a cross-sectional view of the device along line B-B in the figure; The semiconductor element 2 is bonded onto a silver plating film 7 provided on the tab 4 via a conductive paste 8. In FIG. 5, the area where the silver plating film 7 is provided is indicated by diagonal lines. In this embodiment, the silver plating film is provided on the wire joint portion of the external lead 6 for electrical connection with the semiconductor element 2, on the element mounting surface of the tab 4, and on both upper and lower surfaces of the tab suspension lead 3. Since silver is also a noble metal like gold, its surface is inactive and its adhesiveness with the sealing resin 1 is low. Therefore, even if the device is exposed to high temperatures, water vapor generated inside the device can be easily released through the adhesive interface between the silver plating film 7 on the tab suspension lead 3 and the sealing resin. Note that, as in the first embodiment, when this device is used near room temperature, the moisture resistance reliability of the device is not impaired.

In this embodiment, water vapor generated inside the device at high temperatures can easily escape to the outside of the device.

This has the effect of preventing destruction of the device due to steam pressure and improving the reliability of the device.

A fourth embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 is a plan view of a resin pair [E type semiconductor device] using the present invention, and FIG. 8 is a vertical cross-sectional view of the device taken along line A to FIG. The main components of this device are a semiconductor cable 2, an element mounting tab 4, a bonding wire 10,
External lead 6, sealing resin 1, tab suspension lead 3, coating 1
Has 1.

The main components of the coating 11 are Au, Ag, Ru, and Rh.

Noble metals such as Pd, Os, Ir, Pt, or Fe,
Ni, Co, Cr, Ti, Nb, 'I'a.

It is made of a passive state-forming metal such as AQ, and is attached by a plating method, a thin film forming method, or a thick film forming method such as a coating method. Since the surface of this film 11 is made of noble metal or passive, it has inert properties, so the sealing resin 1
The adhesive strength is extremely weak. For this reason, the bonded interface may peel off during device fabrication, or even if it is initially bonded, it may peel off with very weak force. Semiconductor device is at high temperature ()
200° C.), the moisture absorbed by the sealing resin 1 turns into water vapor and generates a large vapor pressure inside the device. However, since the interface between the coating 11 on the tab suspension lead 3 and the sealing resin 1 easily peels off, a path is formed for water vapor to escape from the inside of the device to the surface. Therefore, the water vapor generated inside the device escapes from the device through this path before generating a large pressure that would cause resin cracks.

According to this embodiment, the water vapor generated inside the semiconductor device when it is heated to a high temperature easily escapes to the outside of the device, so that large vapor pressure is not generated inside the device and resin cracking can be prevented. , and there is no need to change the external shape of the device.

The tab 2 has leads (tab suspension leads) that support an element mounting frame that fixes the tab 2 during resin sealing. (FIG. 8) This tab suspension lead 3 reaches from the end of the tab 4 to the surface of the semiconductor device. Therefore, adhesion with the sealing resin is prevented on the surface of the tab suspension lead 3 in advance. Alternatively, if a coating 11 that causes deterioration is provided, peeling will occur at the interface between the tab suspension lead 3 (coating 11) and the resin 1 before the adhesive interface between the tab 4 and the resin 1, and the generated water vapor will flow through this gap. Since the vapor can pass through the device and escape to the outside of the device, excessive vapor pressure is not generated inside the device, and resin cracking can be prevented. Further, since there is no need to change the external shape of the semiconductor device at all, a conventional sealing mold can be used as is.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a plan configuration diagram of a resin-sealed semiconductor device using an example of the present invention, and FIG. 10 is a diagram of FIG.
1 is a cross-sectional view of the device along FIG. The main components of this device are semiconductor elements 2. It consists of a tab 4, an external lead 6, and a sealing resin 1, and a tab suspension lead 3 is provided at a part of the corner of the tab 4.

Note that the bond-in wire in the first embodiment is omitted. In this embodiment, as shown in FIG. 10, the height of the tab 4 and the height of the tab suspension lead 3 are different.
A coating 11 is provided on the surface of the tab suspension lead. Note that this coating 11 does not necessarily need to cover the entire surface of the tab suspension lead 3, and may cover only the lower surface (the side of the tab 4 on which the element 2 is not mounted) or the upper surface. This also applies to the fifth embodiment. Further, the material and forming method of the coating 11 are the same as in the fifth embodiment. Furthermore, when there are a plurality of tab suspension leads 3 as in the present embodiment and the fifth embodiment, it is not necessarily necessary to provide the coating 11 on all the tab suspension leads, but it is necessary to provide the coating on at least one. Bye.

In the semiconductor device of this example, the device is at a high temperature (>20
Even when heated to 0℃), the water vapor generated inside the device
Since the vapor can easily escape to the outside of the device through the gap created at the interface between the coating 11 and the sealing resin 1, a large vapor pressure is not generated inside the device.

According to this embodiment, water vapor generated inside the device when the device is heated to a high temperature can be easily led out of the device without changing the external shape of the resin-type semiconductor device. This has the effect of preventing excessive vapor pressure from occurring within the device, thereby preventing resin cracking in the device.

Next, another embodiment of the present invention will be described with reference to FIGS. 11 and 12. FIG. 11 is a plan view of a resin-sealed semiconductor device using an example of the present invention, and FIG.
- FIG. 3 is a cross-sectional view of the device along line G; The main components of this device are a semiconductor element 2, a sealing resin 1, a tab 4 made of 42NiFe, an external lead 6, and a tab suspension lead 3.The tab suspension strip 3 is provided at the center of each of the four sides of the tab 4. It is.

Note that bonding wires are omitted. The coating 11 of the tab suspension lead 3 in FIG. 12 is coated with an organic molding agent. In the semiconductor device of this embodiment, the portion where the coating 7 is coated is sealed.
This is because the resin l does not adhere.

Even when the device is heated to a high temperature, water vapor generated inside the device escapes to the outside of the device through the gap between the interface between the coating 1 and the sealing resin 1.

By the way, ordinary sealing resin has a coefficient of thermal expansion of 10 to 3.
0 x 10-8/℃, 42 N j, F e
has a value of 3 to 5 x 10"-B/'C. Therefore, when the device is cooled from high temperature to room temperature, sealing resin 1 has a value of 3 to 5 x 10"-B/'C.
, the amount of shrinkage is larger than that of tab 4). In the case of 2′□,
A compressive force acts on the interface between the coating 11 and the resin 1-. Therefore, the coating 7 and the resin 5 are not bonded together but are tightened by compressive force, which prevents moisture from entering the device from outside at around room temperature. Therefore, by providing the coating 7, the moisture resistance of the device does not deteriorate.

According to this example, excessive vapor pressure is generated within the device when the device is heated to a high temperature without changing the external shape of the resin-sealed semiconductor device or deteriorating the moisture resistance of the device. This has the effect of preventing resin cracking in the device.

〔Effect of the invention〕

According to the first invention of the present application, even if a resin-type semiconductor device is exposed to high temperatures, excessive vapor pressure can be prevented from being generated inside the device, and the device can be prevented from being destroyed. This has the effect of improving the reliability of the device.

According to the second invention of the present application, water vapor generated inside the device when the device is heated to a high temperature can be easily taken out of the device without changing the external shape of the resin-sealed semiconductor device. This has the effect of being able to prevent excessive vapor pressure from being generated within the device, preventing resin cracks in the device, and improving the reliability of the device.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a semiconductor device according to a first embodiment of the present invention, FIG. 2 is a horizontal sectional view taken along line A-A in FIG. FIG. 4 is a vertical cross-sectional view of a semiconductor device according to a second embodiment of the present invention, and FIG. 5 is a horizontal cross-sectional view of a semiconductor device according to a third embodiment of the present invention.
6 is a longitudinal cross-sectional view taken along the line B-B in FIG. 5, FIG. 7 is a horizontal cross-sectional view of a semiconductor device according to a fourth embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along the line E-E in FIG. 9 is a horizontal sectional view of the semiconductor device according to the fifth embodiment of this embodiment, FIG. 10 is a vertical sectional view taken along line FF in FIG. 9, and FIG. The figure is a horizontal sectional view of a semiconductor device according to a sixth embodiment of the present invention.
FIG. 12 is a longitudinal sectional view taken along line GG in FIG. 11. DESCRIPTION OF SYMBOLS 1... Injection resin, 2... Semiconductor element, 3... Tab hanging lead, 4... Tab, 5... Gold plating film, 6...
- External lead, 7... Silver plating film, 8... Conductive paste, 9... Crack, 10... Bonding wire, 11... 1 vagueness. Fig. 1 J 2 Fig. Otsu 6-7 Thousand membranes'? -72 Schiff Figure 4) η F Figure d ---77- J-7) Evaluation sort Figure 3 IN) "Q 111?□L

Claims (1)

[Claims] 1. A semiconductor element, a tab on which the semiconductor element is mounted, a tab suspension lead that is integrally formed with the tab and supports the tab, and the tab and the tab suspension lead are arranged separately. In a semiconductor device comprising a plurality of external leads that are connected electrically to the semiconductor element, and a resin that seals the group of these leads and the semiconductor element, the tab and the tab suspension lead on the element mounting side. A semiconductor device characterized in that the entire surface and/or the entire surface on the side opposite to the element mounting side is covered with a noble metal coating, and with respect to the surface of each of the external leads, only the end portion on the side electrically connected to the element is covered with the noble metal coating. 2. A semiconductor element, a tab on which the semiconductor element is mounted, a tab suspension lead formed integrally with the tab and supporting the tab, and a tab and tab suspension lead arranged separately from each other and connected to the semiconductor element. In a semiconductor device comprising a plurality of electrically connected external leads and a resin for sealing these lead groups and a semiconductor element, a noble metal-containing coating and/or a passivation-containing coating is provided on the entire front and back surfaces of the tab suspension lead. A semiconductor device characterized by forming a formed metal film.