Semiconductor device in a resin sealed package with a radiating plate and manufacturing method thereof

The lower end of a resin wall is bonded to a radiating plate, and a lead is fixed so as to extend through the resin wall. After a semiconductor chip is bonded thereto, a resin lid is put to seal the semiconductor chip. Recessed parts for burying the lower end of the resin wall are formed on the side parts of the radiating plate, and protruding parts are further provided within the recessed parts. The lead has holes formed on the package outer part and the resin wall inner part. The loading surface of the semiconductor chip is finished with silver plating, and the package exterior and the lead are plated with gold. The shape fitted to the resin wall is imparted to the resin lid, and the resin lid is further formed into a vertically plane symmetric shape.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates to a semiconductor device and a manufacturing method thereof and, particularly, to a semiconductor device having a semiconductor chip bonded to a radiating plate and sealed with resin [resin-sealed package equipped with radiating plate (plastic package)] and a manufacturing method thereof.

2. Description of the Related Art

In a transistor for large power, generally, a radiating plate made of copper or the like is used in order to enhance the heat radiating property because the transistor generates a large heating value. A semiconductor device having a semiconductor chip bonded to such a radiating plate and sealed with resin, or a resin-sealed package equipped with radiating plate (plastic package) has a structure, for example, as shown inFIG. 1.FIG. 1is a partially cutaway perspective view of a conventional resin-sealed package equipped with radiating plate.

A semiconductor device10shown inFIG. 1is a resin-sealed package equipped with a radiating plate2, which comprises a semiconductor chip1, the radiating plate2, a lead3and a sealing resin5. The radiating plate2is formed of a metal plate such as copper and its alloy, which is plated with silver or the like. The lead3is solely formed by a lead frame. The sealing resin5is a thermosetting resin such as epoxy resin or the like. The semiconductor chip1is a transistor for large power.

The semiconductor device10is generally manufactured as follows. The semiconductor chip1is put on and bonded to the radiating plate2, and the electrode (not shown) of the semiconductor chip1provided on its bonding surface side is electrically connected to the radiating plate2. Electrodes6provided on the upper surface of the semiconductor chip1are connected to the inner lead part3aof the lead3through bonding wires7. Thereafter, these are put in a metal mold, the area provided with the semiconductor chip1of the radiating plate2and the periphery thereof are housed in the cavity of the metal mold, and the sealing resin5is filled therein and molded.

The semiconductor device10thus has a structure in which the sealing resin5is filled in the package, and the semiconductor chip1, the bonding wires7and the inner lead part3aare closely fitted to the sealing resin5and covered with the sealing resin5. The outer lead part3bof the lead3is protruded out of the package to form an external terminal.

The radiating plate2often comprises screw holes4for fixing the semiconductor device10to an aluminum chassis in the mounting of the semiconductor device.

A conventional ceramic package is described in reference toFIG. 2.FIG. 2is a partially cutaway perspective view of a conventional ceramic package equipped with radiating plate.

A semiconductor device11shown inFIG. 2has a ceramic package equipped with a radiating plate2, which comprises a semiconductor chip1, the radiating plate2, a lead3, a ceramic frame8, and a ceramic cap9.

The ceramic frame8is brazed, as shown inFIG. 2, to the center of one main surface of the radiating plate2. Two leads3are brazed to the upper surface of the ceramic frame8opposing to each other. The leads3are brazed to the ceramic frame8so that one-side ends (inner lead parts3a) of the leads3and the other ends (outer lead parts3b) thereof are protruded to the inside and outside of the ceramic frame8, respectively. The semiconductor chip1is put on and bonded to the area surrounded by the ceramic frame8of the radiating plate2, and the electrode (not shown) of the semiconductor chip1provided on its bonding surface side is electrically connected to the radiating plate2. Electrodes6on the upper surface of the semiconductor chip1are connected to the inner lead parts3aof the leads3through bonding wires7. The ceramic cap9is fixed to the upper end of the ceramic frame8to airtightly seal the semiconductor chip1, the bonding wires7and the inner leads3a. Namely, the semiconductor chip1, the bonding wires7and the inner leads3aare airtightly sealed in the hollow structure formed by the radiating plate2, the ceramic frame8, and the ceramic cap9.

The conventional resin-sealed package equipped with radiating plate, however, had the following problems.

The resin-sealed package equipped with radiating plate is used for a semiconductor element with large heating value such as power MOSFET used in an analog amplifier or the like. The temperature of the chip surface is often raised by the heat generated in the high output operation of the semiconductor element to deteriorate or peel the sealing resin closely fitted to the chip surface, which causes the problem that the reliability of the semiconductor device is deteriorated by its characteristic change.

Since the semiconductor chip surface and the bonding wires are covered with the sealing resin, a parasitic capacity based on the sealing resin as dielectric layer is generated. The interference of the parasitic capacity often causes the deterioration of characteristics, for example, in a high frequency band of 1 GHz or more. Accordingly, the problem of deterioration of high frequency characteristics arises in the use for microwave.

The use of the ceramic package is free from such problems, but cannot enjoy the characteristic advantage of the resin-sealed package as described below.

Conventionally, a metal package, a ceramic package and the like have been used for the transistor for large power from the viewpoint of reliability, but it is desired to realize a package sufficiently reliable to the transistor for large power by use of a resin-sealed package (plastic package) made of inexpensive and highly productive molding resin.

The ceramic package can certainly realize high reliability and high performance, compared with the resin-sealed package. However, the ceramic package requires a high manufacturing cost including materials, compared with the resin-sealed package.

The adjustable or selectable range of thermal expansion coefficient in ceramic materials is narrow, compared with resin materials. Therefore, the materials of other members (metal, semiconductor and the like) constituting the semiconductor device which can be used is restricted in a narrow range, or the improvement in reliability by the matching of thermal expansion coefficient is difficult to attain.

Expensive materials such as tungsten copper, molybdenum copper and the like tend to correspond to the materials matched in thermal expansion coefficient to the ceramic materials, and the selectable range of materials is too narrow to select an inexpensive material. The material cost runs up also in this point.

At the present time when the resin-sealed package is becoming the mainstream wedging, makers having ceramic package techniques and facilities therefor are few and specialized, compared with markers having resin mold techniques and facilities therefor. Accordingly, if the resin-sealed package can be substituted with respect to the semiconductor device in which the ceramic package was conventionally adapted, a large-scaled reduction in cost can be expected.

It is desired to extend the application of the resin-sealed package to the use for the transistor for large power or the like, which was the weak point of the resin-sealed package, to inexpensively provide a semiconductor device such as transistor for large power to which high reliability by use of inexpensive and highly productive resin mold package techniques is required.

SUMMARY OF THE INVENTION

The present invention has an object to provide a semiconductor device improved in the reliability and performance of a resin sealed package equipped with radiating plate and a manufacturing method thereof. Further, the present invention has another object to apply the resin-sealed package to a transistor for large power to inexpensively provide it.

More specifically, the present invention has the following objects:

to improve the reliability in high output operation;

to improve the characteristic in high frequency operation;

to improve the adhesion of a resin member to a radiating plate;

to improve the adhesion of the resin member to a lead;

to improve the airtightness and moisture resistance, particularly, to prevent the penetration of moisture, flux, molten solder, corrosive gas or the like from the interface of the lead and the resin member;

to moderate the stress propagated from an outer lead to a resin package body in the cutting of a lead frame or in the mounting of the semiconductor device to keep the bonding force between the lead and the resin member;

to reduce the cost required for external plating while keeping the external corrosion resistance of the semiconductor device by the plating;

to facilitate the assembling in packaging and improve the assembling precision; and

to reduce the warping of the resin member by temperature change.

The semiconductor device according to the first aspect of the present invention comprises a radiating plate; a semiconductor chip bonded onto the radiating plate; a resin wall bonded at the lower end to the radiating plate to surround the circumference of the semiconductor chip; a conductive member extended through the resin wall and retained by the resin wall to electrically conduct the semiconductor chip to the outside; and a resin lid bonded to the upper end of the resin wall. The semiconductor chip is sealed in the space blocked by the radiating plate, the resin wall and the resin lid.

According to the semiconductor device of the first aspect of the invention, the semiconductor chip can be sealed in the hollow structure in no contact with the resin member (in the state isolated therefrom). Therefore, even if the temperature of the chip surface is raised by the heating in high output operation of the semiconductor element, the characteristic of the semiconductor device can be kept without deteriorating the resin member, and the reliability in high output operation can be advantageously improved.

Even when a bonding wire is used for the connection of the semiconductor chip to the conductive member (lead), the bonding wire can be sealed in the hollow structure in no contact with the resin member (in the state isolated therefrom). Therefore, the high frequency characteristic can be advantageously improved without generating the parasitic capacity based on the resin as dielectric layer.

A semiconductor device according to the second aspect of the present invention comprises: a conductive member formed by a lead frame; a radiating plate formed of a metal plate different from the lead frame; a semiconductor chip bonded onto the radiating plate; a resin wall bonded at the lower end to the radiating plate, which retains the conductive member and surrounds the circumference of the semiconductor chip; and a resin lid bonded to the upper end of the resin wall. The semiconductor chip is sealed in the space blocked by the radiating plate, the resin wall and the resin lid. And the conductive member electrically conducts the semiconductor chip to the outside.

According to the semiconductor device of the second aspect of the invention, since the radiating plate is formed of the metal plate different from the lead frame, the radiating plate can be formed by use of a metal plate different in thickness from the metal sheet constituting the lead frame. Thus, the radiating plate can be formed of a metal plate thicker than the metal sheet constituting the lead frame to advantageously enhance the heat radiating property.

Since a plurality of semiconductor devices are assembled on the same lead frame, the carrying in the manufacturing process is advantageously facilitated.

A semiconductor device according to the third aspect of the present invention is characterized by fitting, in a semiconductor device according to the first or second invention, the resin wall to protruding parts or recessed parts provided on the radiating plate.

According to the semiconductor device of the third aspect of the invention, since the resin wall is fitted to the protruding parts or recessed parts provided on the radiating plate, the adhesive area of the radiating plate to the resin can be extended to advantageously improve not only the adhesion of the radiating plate to the resin wall but also the airtightness of the package.

The structure having the combination of protruding parts with recessed parts is also effective. For example, a semiconductor device according to the fourth invention of the application is effective.

The semiconductor device according to the fourth aspect of the present invention is characterized by providing, in a semiconductor device according to the first or second invention, recessed parts on the opposed side parts of the radiating plate, protruding and providing protruding parts on the inner surfaces of the recessed parts, and burying the lower end part of the resin wall in the recessed parts.

A semiconductor device according to the fifth aspect of the present invention is characterized by providing, in a semiconductor device according to the first or second invention, holes in the outside positions of the resin wall on the conductive member.

According to the semiconductor device of the fifth aspect of the invention, since the holes are provided in the outside positions of the resin wall on the conductive member, the rigidity of the conductive member in the positions having such holes is reduced, so that the stress propagated from the outer lead to the resin package body in the cutting of the lead frame or in the mounting of the semiconductor device can be moderated. Consequently, the bonding force of the conductive member to the resin member can be advantageously kept.

A flux or molten solder often penetrates to the bonding interface of the resin and the conductive member and further into the package through the bonding interface. According to the semiconductor device of the fifth aspect of the invention, the flow of the flux or molten solder running over the conductive member outside the package to the package outer surface (the resin wall outer surface) can be entirely or partially stopped by the holes provided in the outside positions of the resin wall on the conductive member. Namely, it can be advantageously reduced that the flux or molten solder flowing on the conductive member outside the package reaches the bonding part of the conductive member to the resin wall, compared with the case having no hole. Consequently, the penetration of the flux or molten solder to the bonding interface of the resin and the conductive member and further into the package through the bonding interface can be advantageously reduced.

A semiconductor device according to the sixth aspect of the present invention is characterized by providing, in a semiconductor device according to the first or second aspect of the invention, first holes in the outside positions of the resin wall on the conductive member, and providing second holes or cutouts in the region extending through the resin wall of the conductive member.

According to the semiconductor device of the sixth aspect of the invention, the same advantage as the fifth invention can be provided by the first holes. Further, since the resin constituting the resin wall is partially filled in the second holes or cutouts provided on the conductive member and hardened therein, the dropping-out of the conductive member can be prevented by the anchor effect to advantageously improve the adhesive strength and bonding strength of the resin wall to the conductive member.

According to the semiconductor device of the sixth aspect of the invention, further, since the bonding interface of the resin and the conductive member can reduced, compared with the case having no second hole or cutout, to narrow or extend the penetrating route of the moisture, flux, molten solder, corrosive gas or the like into the package from the outside, the penetration of the moisture, flux, molten solder, corrosive gas or the like to the bonding interface of the resin and the conductive member and further into the package through the bonding interface can be advantageously reduced.

A semiconductor device according to the seventh aspect of the present invention is characterized by arranging, in the semiconductor device of the sixth invention, the first holes so as to overlap the space area of the second holes or cutouts when the conductive member is seen down in the resin wall direction from the outside of the resin wall.

According to the semiconductor device of the seventh aspect of the invention, the penetrating route of the flux or molten solder into the package from the outside can be more narrowed or extended. The flow of the fluid of the flux or molten solder flowing on the conductive member outside the package to the package outer surface (resin wall outer surface) can be stopped by the first holes, and even if the flux or molten solder partially flows to the space area of the first holes and reaches the package outer surface (resin wall outer surface), the penetration of the flux or molten solder to the bonding interface of the resin and the conductive member and further into the package through the bonding interface can be advantageously prevented by the second holes or cutouts.

A semiconductor device according to the eighth aspect of the present invention is characterized by providing, in a semiconductor device according to the first or second invention, a stepped part to be fitted to the inner periphery of the resin wall on the resin lid.

The semiconductor device of the eighth aspect of the invention has the advantage that the resin lid can be easily and precisely put on the resin wall.

A semiconductor device according to the ninth aspect of the present invention is characterized by forming, in the semiconductor device of the eighth invention, the resin lid so as to have a vertically plane symmetric shape.

According to the semiconductor device of the ninth aspect of the invention, the stepped part plane symmetric to the stepped part to be fitted to the inner periphery of the resin wall provided on the lower surface of the resin lid (package inside surface) is provided on the upper surface (package outside surface) of the resin lid. Therefore, the section vertical to the plane direction of the resin lid has an equal shape, so that the warping of the resin lid by temperature change can be advantageously reduced.

A semiconductor device according to the tenth aspect of the present invention is characterized by finishing, in a semiconductor device according to the first or second invention, the surface of the radiating plate surrounded by the resin wall by silver plating, and surface-finishing the other surface of the radiating plate except the part for bonding the resin wall and the inner lead part and outer lead part of the conductive member by gold plating.

According to the semiconductor device of the tenth aspect of the invention, the base metal and base plating are protected from moisture or the like by the gold plating applied to the exterior, and the external corrosion resistance of the semiconductor device can be advantageously improved. Since the surface of the radiating plate surrounded by the resin wall is finished not by gold plating but by silver plating, the cost required for the plating can be advantageously reduced. Further, since the inner lead part and outer lead part of the conductive member are surface-finished by gold plating, the migration resistance can be advantageously improved. As the whole, the reliability can be improved while reducing the cost.

A manufacturing method of semiconductor device according to the eleventh aspect of the present invention comprises the steps of: forming a conductive member by a lead frame; arranging the lead frame and a radiating plate in a metal mold having a cavity corresponding to a resin wall; clamping the region of the radiating plate, the region forming the inside of the resin wall, by an upper die and a lower die of the metal mold; and molding a resin in the mold to form the resin wall.

According to the manufacturing method of semiconductor device according to the eleventh aspect of the present invention, since the region forming the inside of the resin wall of the radiating plate is clamped by the upper die and lower die of the metal mold, the radiating plate can be advantageously flattened by the clamping force. When the end part of the radiating plate is protruded to the region forming the outside of the resin wall, such an end part is also clamped by the upper die and lower die of the metal mold. Since the radiating plate can be retained within the metal mold even if the end part of the radiating plate is not protruded to the region forming the outside of the resin wall in the manufacturing method of semiconductor device of the eleventh invention, a behavior such as the floating of the radiating plate or the like within the metal mold can be suppressed, and the radiating plate can be advantageously flattened by the clamping force.

A manufacturing method of semiconductor device according to the twelfth aspect of the present invention comprises the steps of: forming a conductive member by a lead frame; forming a radiating plate by a metal plate different from the lead frame; arranging the lead frame and the metal plate within a metal mold having a cavity corresponding to the resin wall; molding a resin in the mold to form the resin wall and then opening the mold; and plating the radiating plate and the conductive member.

A manufacturing method of semiconductor device according to the thirteenth aspect of the present invention further comprises the steps of: as the plating step in the manufacturing method of semiconductor device of the twelfth aspect of the invention, electroplating the radiating plate with silver; electroplating the conductive member with gold; and electroplating the region forming the outside of the rein wall of the radiating plate with gold.

According to the manufacturing method of semiconductor device of the twelfth aspect of the invention or the thirteenth aspect of the invention, the semiconductor device according to the tenth aspect of the invention can be effectively manufactured. Since the radiating plate is formed of a metal plate different from the lead frame used, the lead and the radiating plate can be constituted in the electrically isolated state, and the lead frame and the radiating plate can be independently electroplated without particularly using any mask in the plating process.

In the invention, the hollow package is formed by the radiating plate, the resin wall, and the resin lid, and the shapes of the radiating plate, the lead and the resin lid, the plating method and the like are designed as described above, whereby the assembling in packaging is facilitated, and the assembling precision is improved. The resin sealed package is applied to a transistor for large power or the like, whereby it can be inexpensively proposed.

THE DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The semiconductor device according to preferred embodiments of the present invention and the manufacturing method thereof are described in more detail in reference to the accompanying drawings. The following merely shows an example of the invention and never limits the invention.

First Embodiment

The structure of the semiconductor device12according to the first embodiment of the invention is described in reference toFIGS. 3-8.FIG. 3is a partially cutaway perspective view of the semiconductor device12according to the first embodiment of the invention.

As shown inFIG. 3, the semiconductor device12of the embodiment is a resin-sealed package equipped with radiating plate, which comprises a semiconductor chip1, a radiating plate20, a lead30, a resin wall40and a resin lid50. The resin wall40and the resin lid50are formed of a thermosetting resin such as epoxy resin or the like. In the embodiment, the semiconductor chip1is a transistor for large power.

The radiating plate20consists of a copper plate plated with nickel, silver and gold. The part for bonding the resin wall40of the radiating plate20is not plated, and the resin is directly adhered to the copper plate. The surface of the package exterior part (the outside of the resin wall40) of the radiating plate20is surface-finished by coating nickel plating and silver plating on the base copper plate in this order and plating the outermost surface with gold. The surface of the package interior part (the inside of the resin wall40) of the radiating plate20is surface-finished by plating the base copper plate with nickel and plating the nickel plating with silver (outermost surface). The radiating plate20has screw holes4bored in both the end parts corresponding to the package outside. The screw holes4are for fixing the semiconductor device12to a base material such as aluminum chassis by screws in the mounting of the semiconductor device12.

FIG. 4shows a perspective view of the radiating plate20. The radiating plate20has an end part21, a central part22, an end part23and protruding parts24. The center part22basically has a sheet-like rectangular shape. In the drawing, the lateral direction is taken as length, the vertical direction is taken as width, and the depth direction is taken as thickness. The end parts21and23are integrally and continuously formed on both longitudinal ends of the center part22. The end parts21and23are larger in width than the center part22and protruded to both lateral sides from the side surfaces22aof the center part22to form stepped surfaces21aand23a. A recessed part is formed on each of the mutually opposed side parts of the radiating plate20by the opposed stepped surface21aand stepped surface23aand the side surface22aof the center part22. Three protruding parts24each, six in total, are protruded and provided on the side surfaces22aforming the inner surfaces of the recessed parts. The protruding parts24are protruded in the width direction, but the tips thereof are housed in the recessed part without protruding over the cross-directional (vertical to the width direction) end surfaces of the end parts21and23. As shown inFIG. 5, the lower end of the resin wall40is buried in the recessed parts, and the resin wall40is fitted to the recessed parts and the protruding parts24.FIG. 5is a partially cutaway perspective view of the semiconductor device12according to the first embodiment of the invention seen from the bottom side.

The screw holes4are bored substantially in the centers of the end parts21and23toward the thickness direction.

Referring toFIG. 3again, the lead30is formed of a thin plate of copper, nickel plating fitted thereto, and gold plating (outermost surface) fitted to the nickel plating for surface-finishing. The part covered with the resin wall40is not plated, and the resin is directly adhered to the material (copper plate). The lead30has first holes31in the outside positions of the resin wall40.

FIG. 6shows a plan view of the lead frame39. In the embodiment, the lead30is formed by the lead frame39. The lead frame39is formed of a metal sheet of copper having the pattern of the lead30connected thereto. As shown inFIG. 6, the first holes31, second holes32and cutouts33are worked in the lead30.

FIG. 7Ais a plan view of the resin lid50constituting the semiconductor device12according to the first embodiment of the invention,FIG. 7Bis a side view thereof, andFIG. 7Cis a front view thereof. As apparent fromFIGS. 7B and 7C, the resin lid50has a vertically plane symmetric shape. Protruding parts52are formed on both surfaces of a base part51. Stepped parts53to be fitted to the inner periphery of the resin wall40are formed around the protruding parts52of both the surfaces. Namely, the outer circumferences of the protruding parts52are substantially conformed to the inner circumference of the resin wall40in both dimension and shape so as to be mutually fitted. The outer circumference of the base part51has a dimension and shape corresponding to the outer circumference of the resin wall40.

The illustration is further performed in reference toFIGS. 8A to 8C.FIG. 8Ais a plan view of the semiconductor device12in the state where the resin lid50is removed.FIG. 8Bis a sectional view taken along line A-A inFIG. 8A, which shows the resin lid50.FIG. 8Cis a sectional view taken along line B-B inFIG. 8A, which shows the resin lid50.

As shown inFIGS. 8A to 8C, the semiconductor chip1is bonded to the center of the radiating plate20. The resin wall40surrounds the circumference of the semiconductor chip1and is bonded at the lower end to the radiating plate20. The lead30is extended through the resin wall40and retained (nipped) by the resin wall40. The second holes32and cutouts33of the lead30are provided within the region extending through the resin wall40of the lead30. Namely, the second holes32and cutouts33are buried in the resin wall40. The resin constituting the resin wall40is partially filled and hardened in the second holes32and cutouts33.

The outer lead part30bof the lead30is protruded from the outer wall surface of the resin wall40to the outside of the resin wall40. The inner lead part30aof the lead30is extended in parallel to the inner wall surface of the resin wall40and the radiating plate20on the inside of the resin wall40and formed broader than the outer lead part30bto ensure the bonding area. The inner lead part30ais supported in the state where it is loaded on a base seat part41formed as a part of the resin wall40. According to this, the supporting strength of the inner lead part30ais improved.

The inner lead part30ais connected to the electrodes6of the semiconductor chip1through bonding wires7and electrically connected.

The resin lid50is bonded to the upper end of the resin wall40. The protruding part of the resin lid50is fallen into the resin wall40, and the resin wall40is fitted to the resin lid50. The resin wall40is bonded to the resin lid50through a resin-based adhesive. As the whole, the semiconductor chip1, the bonding wire7and the inner lead part30aare sealed in the space (package) formed by the radiating plate20, the resin wall40and the resin lid50. As shown inFIGS. 8Band C, the semiconductor chip1and the bonding wires7are set within the hollow structure formed by the radiating plate20, the resin wall40and the resin lid50without making contact with the resin.

The method for manufacturing the semiconductor device12of the embodiment is then described. The semiconductor device12is manufactured as follows.

Referring toFIGS. 9A and 9B,FIG. 9Ais a sectional view of a molding metal mold corresponding to the section taken along line A-A inFIG. 8A.FIG. 9Bis a sectional view of the molding metal mold corresponding to the section taken along line B-B inFIG. 8B.

The molding metal mold consisting of an upper die61and a lower die62as shown inFIGS. 9A and 9Bis used. A cavity63corresponding to the resin wall40is formed by the upper die61and the lower die62.

As shown inFIGS. 9A and 9B, the radiating plate20and the lead frame39are put in a prescribed position of the lower die62. Thereafter, the upper die61is put thereon to close the mold. At this time, the radiating plate20and the lead frame39are clamped by the upper die61and the lower die62. The radiating plate20is clamped not only in the outside of the resin wall forming position but also in the inside thereof. The radiating plate20is thus flattened.

After closing the mold, the molten resin is injected and filled in the cavity63. The resin is also filled in the second holes32and cutouts33not shown of the lead30. The resin is then hardened, and the mold is opened to take out the molded product. A structure consisting of the lead frame39, the radiating plate20and the resin wall40as shown inFIG. 10is consequently taken out.

The plating process is then performed.FIGS. 11A to 11Dare typical views showing the coating process of plating in order of steps. As shown by the slash part ofFIG. 11A, the exposed surfaces of the lead frame39including the lead30and the radiating plate20are plated with nickel.

Silver plating is coated onto the nickel plating of the radiating plate20by electroplating as shown by the slash part ofFIG. 11B. Concretely, the radiating plate20is dipped in a solution containing silver ion, and a silver film is electrodeposited on the surface of the nickel plating surface of the radiating plate20with the radiating plate20as negative electrode.

Gold plating is then coated onto the nickel plating of the lead frame39including the lead30by electroplating as shown by the slash part ofFIG. 11C. Concretely, the lead30is dipped in a solution containing gold ion, and a metal film is electrodeposited on the nickel plating surface of the lead30with the lead30as negative electrode.

Further, gold plating is coated onto the region of the radiating plate20, the region forming the outside of the resin wall40(the region forming the package exterior), by electroplating as shown by the slash part ofFIG. 11D. The gold plating is thus coated onto the silver plating. Concretely, the inside (the region forming the package inside) of the resin wall40is masked by photoresist or the like, the radiating plate20is dipped in a solution containing gold ion, and a gold film is electrodeposited on the silver plating surface of the radiating plate20with the radiating plate20as negative electrode.

The semiconductor chip1is then bonded. Concretely, the semiconductor chip1is put on and bonded to the silver-plated surface of the radiating plate20surrounded by the resin wall40through a conductive die bond material, and the electrode (not shown) of the semiconductor chip1provided on its bonding surface side is electrically connected to the radiating plate20.

The electrodes6provided on the upper surface of the semiconductor chip1are connected to the inner lead part30aof the lead30through the bonding wires7.

An adhesive is applied to the upper end of the resin wall40, and the resin lid50is put thereon and bonded.

Thus, a plurality of semiconductor devices12are continuously assembled on the lead frame39.

According to the above processes, the semiconductor device12as shown inFIG. 3is obtained.

In the mounting of the semiconductor device12, the molten solder or flux is adhered to the end part of the outer lead part30b. Even if such a liquid flows on the lead20toward the outer wall surface of the resin wall40, the flow is entirely or partially stopped by the first hole31. Even if the liquid partially reaches the outer wall surface of the resin wall40, the penetration of the flux or molten solder to the bonding interface of the resin wall40and the lead30and further into the package through the bonding interface is reduced by the second holes32and cutouts33.

Second Embodiment

A semiconductor device according to the second embodiment of the invention is described in reference toFIG. 12.FIG. 12is a plan view showing the lead frame of the second embodiment of the invention.

In the semiconductor device of the embodiment, a lead70is used instead of the lead30of the semiconductor device12of the above-mentioned first embodiment.

The lead70is differed in first holes71, compared with the lead30. The first holes71are arranged so as to overlap the space part between one second hole72and the other second hole72adjacent thereto and the space area between the second hole72and a cutout73. According to such a structure, the flow of the liquid flowing over the lead70of the package outer part such as flux, molten solder or the like to the outer wall surface o the resin wall40can be stopped by the first holes71, and even if the flux or molten solder partially flows to the space area between the first holes71and reaches the outer wall surface of the resin wall40, the penetration of the flux or molten solder to the bonding interface of the resin and the lead70and further into the package through the bonding interface can be prevented by the second holes72or the cutouts73.