Package with selective corrosion protection of electrical connection structures

Abstract

A package (100) comprises: a carrier (114); an electronic device (102) mounted on the carrier (114); and an encapsulant (106) which encapsulates at least a portion of the electronic device (102) and only a portion of the carrier (114), so that another exposed portion (115) of the carrier (114) is exposed relative to the encapsulant (106), wherein the exposed portion (115) of the carrier (114) comprises an electrical connection structure (117) and a corrosion protection structure (110), and wherein one of the electrical connection structure (117) and the corrosion protection structure (110) is selectively formed only on a sub-portion of the other of the electrical connection structure (117) and the corrosion protection structure (110) located outside the encapsulant (106).

Description

Technical Field

[0001] The present invention relates to a package, a device, a method of manufacturing a package and a method of use. Background Art

[0002] A package may include an electronic device such as a semiconductor chip mounted on a carrier such as a lead frame. A package may be implemented as an encapsulated electronic device mounted on a carrier with electrical connection structures extending out of the encapsulant and coupled to peripheral electronics.

[0003] However, the package has a limited service life when used under harsh conditions. Summary of the invention

[0004] There may be a need for a package having an increased service life even when used under harsh conditions.

[0005] According to an exemplary embodiment, a package is provided, comprising: a carrier; an electronic device mounted on the carrier; and an encapsulant, which encapsulates at least a portion of the electronic device and only a portion of the carrier, so that another exposed portion of the carrier is exposed relative to the encapsulant, wherein the exposed portion of the carrier comprises an electrical connection structure and a corrosion protection structure, one of the electrical connection structure and the corrosion protection structure being selectively formed only on a sub-portion of the other of the electrical connection structure and the corrosion protection structure located outside the encapsulant.

[0006] According to another exemplary embodiment, a device is provided, which includes a mounting structure (eg, a printed circuit board, PCB) and a package having the above-mentioned features and mounted on the mounting structure such that an electrical connection structure is electrically connected to the mounting structure.

[0007] According to another exemplary embodiment, a method for manufacturing a package is provided, wherein the method includes: mounting an electronic device on a carrier; encapsulating at least a portion of the electronic device and only a portion of the carrier by an encapsulant so that another exposed portion of the carrier is exposed relative to the encapsulant; and forming the exposed portion of the carrier to have an electrical connection structure and a corrosion protection structure so that one of the electrical connection structure and the corrosion protection structure is selectively formed only on a sub-portion of the other of the electrical connection structure and the corrosion protection structure that is located outside the encapsulant.

[0008] According to another exemplary embodiment, a package having the above features is used for outdoor applications in corrosive environments.

[0009] According to an exemplary embodiment, a package having an encapsulated electronic device on a carrier is provided, wherein the carrier partially extends out of the encapsulant with its exposed portion. The exposed portion of the carrier includes an electrical connection structure for electrically connecting the package to an electronic environment, and includes a corrosion protection structure for protecting the electrical connection structure from corrosion, i.e., for inhibiting, preventing or even eliminating the corrosion of the electrical connection structure. The electrical connection structure and the corrosion protection structure are partially formed on each other so as to be closely related to each other in space, thereby achieving efficient corrosion protection of the electrical connection structure. However, by selectively covering only a portion of one of the structures with only another structure, it can be ensured that both the corrosion protection structure and the electrical connection structure remain exposed to the environment outside the encapsulant. This can simplify and improve the electrical connection of the package relative to the peripheral electronic device. Therefore, the electrical reliability of the package can be significantly improved while providing effective corrosion protection.

[0010] Therefore, a corrosion resistant package can be provided. In particular, the semiconductor package can be provided with a metal lead of a first metal serving as an electrical connection structure, the metal lead of the first metal being in electrical contact with a second metal serving as an electron donor with respect to the first metal, thereby serving as a corrosion protection structure.

[0011] Description of Other Exemplary Embodiments

[0012] In the following, further exemplary embodiments of packages, devices and methods will be explained.

[0013] In the context of the present application, the term "package" may particularly denote an electronic device comprising one or more electronic devices mounted on a carrier and optionally encapsulated using an encapsulant. Further optionally, one or more conductive contact elements (e.g. bonding wires or clips) may be implemented in the package, for example, for electrically coupling the electronic device to the carrier.

[0014] In the context of the present application, the term "carrier" may particularly refer to a support structure (preferably, but not necessarily, electrically conductive) that acts as a mechanical support for the one or more electronic devices and may also facilitate electrical connections between the electronic devices and peripheral devices of the package. In other words, the carrier may fulfill both a mechanical support function and an electrical connection function.

[0015] In the context of the present application, the term "electronic device" may include in particular semiconductor chips (in particular power semiconductor chips), active electronic devices (such as transistors), passive electronic devices (such as capacitors or inductors or ohmic resistors), sensors (such as microphones, light sensors or gas sensors), actuators (such as loudspeakers) and microelectromechanical systems (MEMS). In particular, the electronic device may be a semiconductor chip having at least one integrated circuit element (such as a diode or a transistor) on its surface portion. The electronic device may be a bare die, or may already be packaged or encapsulated.

[0016] In the context of the present application, the term "encapsulant" may particularly refer to a portion of the electronic device and optionally a carrier that surrounds (e.g., hermetically surrounds) the electronic device to provide mechanical protection, electrical isolation, and optionally facilitate heat removal during operation. Such an encapsulant may be, for example, a molding compound. When encapsulated by molding, for example, injection molding or transfer molding may be performed.

[0017] In the context of the present application, the term "corrosion protection structure" may particularly denote a physical body made of one material, which protects another material of an exposed carrier part, i.e. an electrical connection structure, from corrosion. Such corrosion protection may be due to the fact that the corrosion protection structure is chemically more willing to donate electrons during the corrosion process than the material of the electrical connection structure. For example, the corrosion protection structure may be made of a metal or alloy that is less noble than another metal or alloy of the electrical connection structure.

[0018] In the context of the present application, the term "electrical connection structure" may particularly denote a portion of an encapsulant outer lead portion of an exposed portion of a carrier, which is configured and intended to be electrically connected to a peripheral electronic device, such as to a mounting structure (e.g., a printed circuit board). For example, the package may be mounted on such a mounting structure by soldering, sintering or welding the electrical connection structure to the mounting structure, or by pressing the electrical connection structure into a plated hole of the mounting structure. In particular, the electrical connection structure may be used to establish an electrical connection of the package relative to an electronic environment, the electrical connection function not being disturbed by corrosion.

[0019] In the context of the present application, the term "structure selectively formed only on a sub-portion of another structure" may particularly mean that the structure covers a sub-portion of the other structure, but leaves the remaining sub-portion of the other structure free or exposed. In an alternative, the electrical connection structure may be formed on a portion of the surface of the corrosion protection structure, but another surface portion of the corrosion protection structure may be left exposed. In another alternative, the corrosion protection structure is formed on a portion of the surface of the electrical connection structure, but another portion of the electrical connection structure is left exposed. Therefore, in one embodiment, the corrosion protection structure is selectively formed only on a sub-portion of the electrical connection structure that is located outside the encapsulant, for example see Figure 1 In another embodiment, the electrical connection structure is selectively formed only on the sub-portion of the corrosion protection structure located outside the encapsulant, for example, see Figure 3 By taking such measures it can be ensured that both the electrical connection structure and the corrosion protection structure forming part of the carrier portion exposed to the encapsulant can fulfil their functions without being deteriorated or impaired by undesired complete covering of the respective structures by the respective other structures.

[0020] In one embodiment, the corrosion protection structure is made of a material configured to be able to act as an electron donor for the electrical connection structure. In other words, the material of the corrosion protection structure can be a metal or alloy that is less noble than another metal or alloy of the electrical connection structure. The electronegativity of the material of the electrical connection structure can be higher than the electronegativity of the material of the corrosion protection structure. In the event of a corrosion attack, the corrosion protection structure will be corroded instead of the electrical connection structure.

[0021] In one embodiment, the electrical connection structure comprises or consists of a material from the following group: copper, gold, silver, palladium, iron, nickel, and an alloy comprising at least one of the materials. However, the electrical connection structure may also be made of other materials. It is preferred to manufacture the electrical connection structure from copper because this material is highly compatible with packaging technology.

[0022] In one embodiment, the corrosion protection structure comprises or consists of a material from the following group: aluminum, titanium, tantalum, niobium, magnesium, tin, zinc, and an alloy comprising at least one of the materials. However, the corrosion protection structure may also be made of other materials. A preferred material for the corrosion protection structure may be, for example, aluminum, because this material is highly compatible with packaging technology.

[0023] In one embodiment, the corrosion protection structure is strip-shaped. The strip-shaped corrosion protection structure can, for example, have a rectangular shape. This has the advantage that corrosion protection is provided along the approximate extension of the strip, i.e. the entire extension of the strip. Furthermore, the strip-shaped corrosion protection structure can be manufactured based on a bimetallic strip, which can, for example, be arranged on a roll (see Figure 6 and Figure 7 ).

[0024] In one embodiment, the electrical connection structure forms the body or bulk of the exposed portion of the carrier, to which the corrosion protection structure is applied with a significantly smaller volume, in particular with no more than 50% of the volume of the electrical connection structure. In terms of description, the electrical connection structure can thereby form a base structure providing a surface portion on which the corrosion protection structure can be applied, for example deposited. By taking this measure, a low-ohmic and high-performance electrical connection can be ensured.

[0025] In another embodiment, the corrosion protection structure forms the bulk of the exposed portion of the carrier, the electrical connection structure being applied to the corrosion protection structure with a significantly smaller volume, in particular with no more than 50% of the volume of the corrosion protection structure. In such an embodiment, the corrosion protection structure may form a matrix of the encapsulant outer carrier portion providing a surface portion on which the material of the electrical connection structure may be applied, for example deposited. Such an embodiment may be preferred in the event of an extremely corrosive atmosphere or corrosion attack.

[0026] In one embodiment, the carrier has at least one metal lead. The at least one lead may include an electrical connection structure made of at least one first metal and may include a corrosion protection structure made of at least one second metal that protects the at least one first metal from corrosion. In particular, a plurality of leads may be provided, which may extend parallel to each other, for example. In such an embodiment, the carrier may be, for example, a lead frame.

[0027] In one embodiment, the at least one first metal and the at least one second metal extend in parallel along a portion of the at least one lead or even along the entire at least one lead. Thus, the first metal can be protected from corrosion along the parallel extension of the first and second metals. The parallel extension between the first metal and the second metal can be substantially along the entire encapsulant outer portion of the lead (e.g., see Figure 1 ) or only along a portion thereof (see, for example, Figure 2 ) extends. In the former embodiment, a very efficient corrosion protection can be achieved. In the latter embodiment, in particular, the end portion of the respective lead can be provided completely by the first metal, thereby facilitating a proper electrical connection along a sufficiently large connection area. In the former embodiment, a very efficient corrosion protection can be achieved.

[0028] In one embodiment, the at least one second metal extends between two sections of the at least one first metal along the extension direction of the at least one lead. Figure 3 and Figure 4Such an embodiment is shown in . For example, the opposite end portions of the respective leads can be provided by a (particularly more noble) first metal, thereby allowing appropriate connection of the package to the electronic environment and the encapsulated electronic device to the leads, for example by wire bonding. The region in between can be formed by a (particularly less noble) second metal, thereby providing very efficient corrosion protection. Electrical signals or currents can also be conducted along both the first metal and the second metal.

[0029] In a preferred embodiment, the package comprises a corrosion protection enhancement structure, which at least partially covers the corrosion protection structure and is configured to enhance the corrosion protection of the corrosion protection structure. Very advantageously, the corrosion protection structure can in turn be partially or completely covered by the corrosion protection enhancement structure to further enhance the corrosion protection capability of the package. For example, such a corrosion protection enhancement structure can be a coating of the corrosion protection structure, which enhances the corrosion protection capability of the corrosion protection structure and / or protects the corrosion protection structure itself from corrosion. Thus, the overall corrosion protection of the electrical connection structure can be significantly enhanced.

[0030] In one embodiment, the corrosion protection enhancement structure comprises at least one of the group consisting of an anodic oxidation coating, a secondary corrosion protection structure made of a material configured to act as an electron donor for the corrosion protection structure, a passivation coating, a phosphating coating, a weld overlay coating, a plasma oxidation coating, and a plasma ceramic conversion coating. However, other methods of forming the corrosion protection enhancement structure are also possible.

[0031] In one embodiment, the corrosion protection enhancement structure selectively covers the corrosion protection structure without covering the electrical connection structure. Thus, the electrical connection structure can remain free of the corrosion protection enhancement structure (which can therefore only be selectively applied on the corrosion protection structure) in order to prevent any adverse effects of the corrosion protection enhancement structure on the electrical connection function of the electrical connection structure. This can ensure that the electrical connection function of the electrical connection structure is not affected by the corrosion protection enhancement structure.

[0032] In one embodiment, the carrier comprises a lead frame. In particular, such a lead frame may include a device mounting section (in particular a die pad) carrying the electronic device and one or more leads for electrically coupling the electronic device to a peripheral electronic device. More particularly, the corrosion protection structure may be formed on and / or as part of at least one of the one or more leads. For example, such a lead frame may include an electrical connection structure made of copper and a corrosion protection structure made of aluminum.

[0033] In one embodiment, the lead frame can be a sheet metal structure that can be patterned to form one or more die pads or mounting sections for mounting the one or more electronic devices of the package, and one or more lead sections for electrical connection of the package to the electronic environment when the electronic device is mounted on the lead frame. In one embodiment, the lead frame can be a metal plate (particularly made of copper), which can be patterned, for example, by stamping or etching. It is cost-effective and mechanically and electrically advantageous to form the chip carrier as a lead frame, wherein the low-ohmic connection of the at least one electronic device can be combined with the sturdy support capacity of the lead frame. In addition, due to the high thermal conductivity of the metal (particularly copper) material of the lead frame, the lead frame can contribute to the thermal conductivity of the package and can remove the heat generated during the operation of the electronic device. The lead frame can include, for example, aluminum and / or copper. In the context of the present application, the term "die pad" can particularly refer to a part of a lead frame that is shaped and sized to receive an electronic device such as a semiconductor chip. Accordingly, the surface area of ​​the die pad is generally flat and planar, and is large enough to fully receive the chip or die thereon. In contrast, the term "lead" can particularly represent another part of the lead frame, which can at least partially extend out of the encapsulant (if present) and act as a connecting element to the peripheral electronic device of the package. For example, it is possible that one or more terminals of the electronic device mounted on the die pad are electrically connected to a corresponding one of the leads, for example, by a clip, a bonding wire or a bonding tape. For example, it is possible that the die pad is encapsulated and the leads are partially or completely exposed relative to the encapsulant. It is also possible that the die pad forms the central part of the lead frame type carrier, and the leads can form the peripheral part of the lead frame. Both the die pad and the leads can at least partially include a metal material. More generally, the carrier can be a partial or complete metal structure.

[0034] In another embodiment, the carrier comprises a stack consisting of a central electrically insulating thermally conductive layer (e.g. a ceramic layer), a corresponding conductive layer (e.g. a copper layer or an aluminum layer) covered on two opposite main surfaces of the central electrically insulating thermally conductive layer, wherein the corresponding conductive layer can be a continuous or patterned layer. In particular, the carrier can be implemented as a direct copper bonding (DCB) substrate or a direct aluminum bonding (DAB) substrate. In such an embodiment, one of the conductive layers can be covered by another metal, which is more expensive or less expensive than the material of the metal layer. Therefore, the metal layer can act as an electrical connection structure or as a corrosion protection structure having a corrosion protection structure selectively applied only on a portion of the surface of the metal layer or an electrical connection structure.

[0035] In one embodiment, the electronic device is mounted on the carrier by at least one of the group consisting of a solder structure, a sintering structure, a welding structure and a gluing structure. However, other connection methods are also possible.

[0036] In one embodiment, the carrier is configured as a bulk structure for mechanically supporting the mounted electronic device and / or for electrically contacting the mounted electronic device. Thus, the carrier can perform a dual function. On the one hand, the carrier can support the electronic device (e.g., on a die pad), and in addition, the carrier can also electrically connect the mounted electronic device to the electronic environment of the package (e.g., via conductive connection elements, such as bonding wires or clips).

[0037] In one embodiment, the connected electrical connection structure and corrosion protection structure can be formed by providing a bimetallic strip, by laser welding or by selective plating. For example, the bimetallic strip can be formed by rolling to connect two different metals (especially more noble metal and less noble metal). Such a bimetallic strip can be formed in particular as a section of an annular preform of a carrier lead wound on a roll. This allows the lead forming a part of the carrier to be efficiently manufactured to provide the connected electrical connection structure and corrosion protection structure. Alternatively, the first metal or alloy can be welded to the second metal or alloy by laser welding to obtain the connected electrical connection structure and corrosion protection structure. In this regard, laser welding is particularly advantageous. In addition, the electrical connection structure can also be selectively plated on the corrosion protection structure, and vice versa. However, it should be noted that the plating process is only selective, that is, one of the structures is only partially covered with another of the structures, so that the exposed surface portion of the electrical connection structure and the corrosion protection structure is maintained. For example, selective plating can be achieved by covering the surface portion of the corresponding structure that should not be plated with a protective material and removing the protective material after the plating is completed.

[0038] In one embodiment, the package is configured as a sensor package. Due to the nature of their functions, sensor packages are in many cases exposed to highly corrosive environments. Therefore, the sensor device or sensor chip, which is an example of an electronic device of the package, needs to be located in a location with highly corrosive influences to perform its sensing task. Therefore, providing corrosion protection structures, especially providing corrosion protection on the encapsulant outer lead portion of the carrier of the package, may be very beneficial for sensor applications.

[0039] In one embodiment, the package can be used in outdoor applications, which can be automotive applications. In particular, it may be advantageous to use the package as a sensor in the exhaust system of a vehicle. In automotive applications, a highly corrosive environment is often present. Therefore, the advantages obtained by the corrosion protection structure of the package are particularly evident in the automotive field.

[0040] In another embodiment, the outdoor application is a wind power plant application, in particular the package is used as a sensor on an offshore wind power plant. Furthermore, in the field of wind power plants, in particular when used as an offshore wind power plant, a highly corrosive environment exists. Both seawater and sea air contain high salt concentrations and may therefore act as a highly corrosive environment. Therefore, it may be very advantageous to provide a package (in particular a sensor package) with a corrosion protection structure on the encapsulant outer lead portion for wind power plant applications.

[0041] In one embodiment, the package includes a plurality of electronic devices mounted on a carrier. Thus, the package may include one or more electronic devices (eg, at least one passive device, such as a capacitor, and at least one active device, such as a semiconductor chip).

[0042] In one embodiment, the encapsulant may include a molded object, in particular a plastic molded object. For example, a corresponding encapsulant (in particular an electronic device with a carrier) may be provided by placing one or more structures between an upper mold and a lower mold and injecting a liquid molding material therein. After the molding material solidifies, the formation of the encapsulant is completed. If necessary, the molded object may be filled with particles that improve its performance, such as its heat dissipation performance. In other exemplary embodiments, the encapsulant may also be a laminate or a cast component.

[0043] In one embodiment, the package includes a conductive connection structure that electrically connects the mounted electronic device to the carrier. For example, the conductive connection structure may include at least one of the group consisting of a clip, a wire bonding structure, and a tape bonding structure. The clip may be a three-dimensionally curved plate-type connection element having two flat sections for connecting to the upper main surface of the corresponding electronic device and the upper main surface of the carrier, wherein the two flat sections are connected by an inclined connection section. As an alternative to such a clip, a wire bonding structure or a tape bonding structure may also be used, which is a flexible conductive wire or strip, one end portion of which is connected to the upper main surface of the corresponding electronic device and the other opposite end portion is electrically connected to the carrier.

[0044] In one embodiment, the at least one electronic device includes at least one of the group consisting of a controller circuit, a driver circuit and a power semiconductor circuit. All these circuits can be integrated into one semiconductor chip, or integrated into different chips respectively. For example, corresponding power semiconductor applications can be implemented by one or more chips, wherein the integrated circuit elements of such power semiconductor chips can include at least one transistor (especially MOSFET, metal oxide semiconductor field effect transistor), at least one diode, etc. In particular, circuits that implement half-bridge functions, full-bridge functions, etc. can be manufactured.

[0045] As a substrate or wafer for the semiconductor chip, a semiconductor substrate, i.e. a silicon substrate, can be used. Alternatively, a silicon oxide or another insulator substrate can also be provided. A germanium substrate or a III-V semiconductor material can also be implemented. For example, exemplary embodiments can be implemented with GaN or SiC technology.

[0046] The above and other objects, features and advantages of the present invention will become apparent from the following description and appended claims taken in conjunction with the accompanying drawings, in which like parts or elements are designated by like reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which are included to provide a further understanding of exemplary embodiments of the invention and constitute a part of this specification, illustrate exemplary embodiments of the invention.

[0048] In the attached picture:

[0049] Figures 1 to 5 A three-dimensional view of a package having a corrosion protection structure according to an exemplary embodiment is shown.

[0050] Figure 6 and Figure 7 A three-dimensional view of a roll of a preform having a combined electrical connection structure and corrosion protection structure for a package according to an exemplary embodiment is shown.

[0051] Figure 8 A schematic diagram of a vehicle having a package according to an exemplary embodiment is shown.

[0052] Fig. 9 A schematic diagram of an offshore wind energy installation with an enclosure according to an exemplary embodiment is shown.

[0053] Fig.10 A cross-sectional view of the leads of a leadframe type carrier of a package according to an exemplary embodiment is shown.

[0054] Fig.11 A cross-sectional view of leads of a leadframe type carrier of a package according to another exemplary embodiment is shown.

[0055] Fig.12 A cross-sectional view of a device according to an exemplary embodiment is shown, the device including a package mounted on and electrically connected to a mounting structure. DETAILED DESCRIPTION

[0056] The illustrations in the drawings are schematic and not drawn to scale.

[0057] Before the exemplary embodiments will be described in more detail with reference to the accompanying drawings, some general considerations will be summarized based on the developed exemplary embodiments.

[0058] In many applications, integrated circuits and electronic systems are exposed to humid or corrosive atmospheres. The risk is that metal structures or contacts of the integrated circuit or the surrounding system will be damaged. This can happen, for example, to sensors in anti-lock braking systems in vehicles (which may be exposed to salt spray), power electronics in trains (which may be exposed to humidity), pressure sensors in exhaust systems in cars, etc.

[0059] Protection against corrosive media is difficult. With the help of protective coatings, some improvement is possible. However, since almost every organic material has a certain potential for hygroscopicity, aqueous corrosive media are also easily absorbed by these materials and cannot effectively protect the integrated circuits for a long time.

[0060] According to an exemplary embodiment, a semiconductor package having a metal lead of a first metal is provided, wherein the metal lead of the first metal is in electrical contact with a second metal that acts as an electron donor (or acceptor) relative to the first metal. Therefore, the second metal can be used as a sacrificial anode for the first metal and can provide efficient corrosion protection for the first metal. Therefore, the exemplary embodiment combines a package with a sacrificial metal that corrodes faster than the metal in the package and can be used as a sacrificial anode in view of the specific requirements of the semiconductor when the semiconductor is exposed to a corrosive atmosphere. If the user exposes the electronic system to a humid or corrosive atmosphere, the provision of a corrosion protection structure can help the user by providing a packaged integrated circuit with an integrated corrosion protection function. This can protect the package alone and further protect the contacts and adjacent surrounding devices of the package in more complex electronic systems.

[0061] In one embodiment, a corrosion resistant sensor package can be created by providing a current anode. In one application, this can inhibit corrosion of a pressure sensor in a vehicle exhaust tract or exhaust system due to nitric acid and / or other corrosive media.

[0062] A problem with packages, in particular sensor packages, is the corrosion of the sensor (eg magnet) due to water, salt or other corrosive media.

[0063] To overcome these drawbacks, exemplary embodiments add sacrificial anodes to the critical sensor package. Depending on the electrochemical series of elements, an appropriate material combination between such a corrosion protection structure and the electrical connection structure is usually possible. Compared to the electrical connection, the corrosion protection structure is usually made of less expensive materials.

[0064] In various embodiments, cathodic corrosion protection or sacrificial anode arrangements are possible. In particular, metal combinations of less noble and more noble metals or layers are possible. In a lead frame design, i.e., in a design in which the carrier is a lead frame, this can be done in order to protect the functional area from corrosion by providing sacrificial anode or cathodic corrosion protection, respectively.

[0065] As anode material, non-noble metals can be used as sacrificial anodes, for example made of aluminum, titanium, tantalum, niobium, magnesium or alloys thereof.

[0066] In particular, a combination of a copper lead frame with one or more of the metals or alloys of the abovementioned anode materials may be advantageous.

[0067] In another embodiment, the aluminum or aluminum alloy lead frame may be provided with a local copper deposition or an additional copper lead frame.In addition to or as an alternative to providing copper, other noble metals may also be used, such as gold, silver, palladium, etc.

[0068] In a preferred embodiment, the corrosion protection structure may be covered by a corrosion protection enhancement structure, which enhances the corrosion protection function of the corrosion protection structure. Such a corrosion protection enhancement structure may be applied based on cathodic corrosion protection or providing a sacrificial anode, etc. The formation process and materials of such a corrosion protection enhancement structure may be as follows:

[0069] In a first embodiment, the corrosion protection enhancement structure can be formed by anodizing a sacrificial anode. This treatment can be performed in particular on aluminum or an alloy (such as an aluminum alloy or brass) combined with a copper lead frame, and can be performed with little effort. The aluminum itself can be anodized and thus converted into aluminum oxide. This also protects the actual sacrificial anode, i.e., the corrosion protection structure. Therefore, the sacrificial anode forming the corrosion protection structure can be oxidized on its surface. The thicker the oxidized corrosion protection structure on the surface, the longer the corrosion protection enhancement structure delays the corrosion attack on the corrosion protection structure.

[0070] In a second embodiment, the corrosion protection enhancement structure may be formed by a secondary corrosion protection structure, i.e. a coating that is less expensive than the underlying corrosion protection structure. The secondary corrosion protection structure (e.g. a zinc coating) provided as a corrosion protection enhancement structure may be an inorganic or organic protective layer on a corrosion protection structure (e.g. made of iron).

[0071] In a third embodiment, a corrosion protection enhancement structure may be formed by a sealing layer. In particular, the corrosion protection of the sacrificial anode itself may be increased. Providing a sealing layer as a corrosion protection enhancement structure to seal the corrosion protection structure against corrosion attack may also improve the overall corrosion protection function.

[0072] In a fourth embodiment, a corrosion protection enhancement structure can be formed by phosphating, i.e., forming a phosphide layer. More particularly, the corrosion protection of the sacrificial anode itself can be increased by additional zinc deposition to further improve the corrosion protection. For example, wire bonding and user-specific configuration of functional areas can be combined with such a treatment to apply precious metals (e.g., silver, copper, gold, palladium, etc.). Such a treatment can advantageously act only selectively on aluminum. The phosphide layer can act as a temporary corrosion layer that is only formed on the less expensive corrosion protection structure and not on the more expensive electrical connection structure. Thus, selective corrosion protection can be formed, for example, on a bimetallic strip.

[0073] In a fifth embodiment, the corrosion protection enhancement structure can be formed by cladding or coating. Many metals can be applied as sacrificial layers on copper by themselves, or on aluminum or alloys (as sacrificial anodes of the corrosion protection structure) to enhance corrosion protection there. In particular, one or more functional layers can be applied for wire bonding and user-specific applications. Overlay welding can form a welded connection by supplying a welding material that is applied with a material that is even less expensive than the material of the corrosion protection structure, which in turn is less expensive than the material of the electrical connection structure.

[0074] In a sixth embodiment, a corrosion protection enhancement structure can be formed by performing plasma oxidation on aluminum or the like. Therefore, the corrosion protection of the sacrificial anode or the corrosion protection structure itself can be increased by plasma oxidation. The configuration of wire bonding and user-specific functional areas can be combined with such a treatment to apply precious metals (such as silver, copper, gold, palladium, etc.). Such a treatment can be performed selectively only on aluminum. Therefore, a material having a corrosion protection structure with low preciousness can be treated with plasma, thereby improving the corrosion resistance of the electrical connection structure by increasing the corrosion protection function of the corrosion protection structure. At this time, the modified surface of the corrosion protection structure as a result of plasma oxidation can form a corrosion protection enhancement structure.

[0075] In a seventh embodiment, a corrosion protection enhancement structure can be formed by forming a plasma ceramic conversion layer. This can increase the corrosion protection of the sacrificial anode or the corrosion protection structure itself as an aluminum anode. Similarly, the formation of wire bonding and user-specific functional areas can be combined with such a treatment to apply precious metals (e.g., silver, copper, gold, palladium, etc.). Similarly, this treatment can be advantageously performed selectively only on aluminum. The plasma ceramic conversion layer can be a separate nanoceramic layer covering the sacrificial anode in the form of a corrosion protection structure. For example, corundum, a specific form of aluminum oxide, can be formed as a plasma ceramic conversion layer on aluminum as a corrosion protection structure. Advantageously, this plasma ceramic conversion layer can have high ductility, that is, it can be non-brittle, which also improves the mechanical properties of the package.

[0076] Figures 1 to 5 A three-dimensional view of a package 100 with a corrosion protection structure 110 according to an exemplary embodiment is shown.

[0077] refer to Figure 1 , a semiconductor sensor package 100 is shown, which includes a lead frame type carrier 114, an electronic device 102 (e.g., a semiconductor chip, in particular a sensor chip) mounted on the carrier 114, and a molded encapsulant 106 encapsulating the electronic device 102 and only a portion of the carrier 114. Given that this is only a partial encapsulation, another exposed portion 115 of the carrier 114 (which may also be indicated as an encapsulant-outside carrier portion) is exposed relative to the encapsulant 106 and thus extends outside the encapsulant 106.

[0078] As shown, the exposed portion 115 of the carrier 114 includes an electrical connection structure 117, which is configured to enable an electrical connection (e.g., a solder connection) between the package 100 and a peripheral electronic device such as a printed circuit board (PCB, not shown). In addition, the exposed portion 115 also includes a corrosion protection structure 110 configured to prevent corrosion of the electrical connection structure 117. The corrosion protection structure 110 is selectively formed only on a sub-portion of the electrical connection structure 117 that is located outside the encapsulant 106. Therefore, a portion of the electrical connection structure 117 remains exposed to the environment, which significantly improves the quality of the conductive connection between the electrical connection structure 117 and the peripheral electronic device. In order to achieve its corrosion protection function, the corrosion protection structure 110 is also exposed to the environment and is made of a material that is configured to be used as an electron donor for the electrical connection structure 117 during a corrosion attack. For example, the electrical connection structure 117 includes or consists of copper. In contrast, the corrosion protection structure 110 includes or consists of aluminum, which is less expensive than copper.

[0079] As shown in the figure, the lead frame type carrier 114 has a plurality of metal leads 126 extending in parallel, each of the metal leads 126 includes a corresponding electrical connection structure 117 made of copper and a corresponding corrosion protection structure 110 made of aluminum (or zinc) which is less noble than copper, so that copper corrosion can be prevented. As shown in the figure, the corresponding electrical connection structure 117 and the corresponding corrosion protection structure 110 of each lead 126 extend parallel to each other along the corresponding encapsulant outer portion of the corresponding lead 126.

[0080] As already mentioned, the carrier 114 is implemented as a lead frame, which includes a die pad as a device mounting section 124 carrying the electronic device 102 and three parallel leads 126 for electrically coupling the electronic device 102 with peripheral electronic devices. As previously mentioned, each corrosion protection structure 110 is formed as a part of a corresponding one of the plurality of leads 126. Figure 1As shown, each corrosion protection structure 110 is located outside the encapsulant 106 .

[0081] according to Figure 1 , the electrical connection structure 117 forms the bulk of the exposed portion 115 of the carrier 114, and the corrosion protection structure 110 is applied only to a sub-portion of the surface of the electrical connection structure 117 with a much smaller volume compared to the volume of the electrical connection structure 117. For example, each corrosion protection structure 110 may be applied by selective plating (or optionally based on, for example, Figure 6 and Figure 7 The bimetallic strip shown is formed on the designated electrical connection structure 117, or by laser welding.

[0082] therefore, Figure 1 The addition of a corresponding sacrificial anode material as a corrosion protection structure 110 onto a corresponding IC (integrated circuit) package metal in the form of an electrical connection structure 117 is shown.

[0083] Thus, a conventional lead frame, for example made of copper, may be used as carrier 114. Additional sacrificial anode metal, for example zinc or aluminum, may be added to each lead 126 of the carrier 114 to provide a corresponding corrosion protection structure 110.

[0084] according to Figure 1 The upper main surface of the electronic device 102 is electrically connected to the leads 126 of the lead frame carrier 114 via bonding wires 180. As an alternative to bonding wires 180, other conductive connecting elements (e.g., clips or bonding tapes) may also be used to connect the electronic device 102 to the leads 126 of the carrier 114.

[0085] Figure 2 Examples and Figure 1 The embodiment of the invention is different in that, according to Figure 2 , the corrosion protection structure 110 of each lead 126 extends only along a sub-portion of the encapsulant outer lead section of the carrier 114. Therefore, the free end of the lead 126 is formed only by the material of the electrical connection structure 117, and not by the material of the corrosion protection structure 110. This simplifies and improves the electrical connectivity of the lead 116 to the electronic environment (e.g., a printed circuit board or other mounting base).

[0086] refer to Figure 3, the corrosion protection structure 110 forms the aluminum body of the lead 126 of the carrier 114. The copper material of the electrical connection structures 117, 119 is applied only to two spaced-apart sub-portions of the corrosion protection structure 110, and the volume of the two spaced-apart sub-portions is significantly smaller than the volume of the corrosion protection structure 110. The electrical connection structure 117 is exposed and extends outside the encapsulant 106, while the electrical connection structure 119 is encapsulated in the encapsulant 106. Therefore, the corrosion protection structure 110 of each lead 126 extends between the two noble metal sections of the electrical connection structures 117, 119 along the extension direction of the corresponding lead 126. In other words, Figure 3 The embodiment of the invention adds a section of noble metal to a sacrificial substrate. Thus, it is possible to manufacture the lead frame based on a conventional lead frame (for example, made of aluminum). Figure 3 In an embodiment of the present invention, an additional noble metal such as copper is selectively applied to the lead frame to form electrical connection structures 117, 119. During chemical stress, the sacrificial body metal of the corrosion protection structure 110 is corroded, while the noble copper material of the electrical connection structures 117, 119 remains stable at the electrical contact position. Therefore, the electrical contact portions of the electrical connection structures 117, 119 are protected.

[0087] exist Figure 3 In the embodiment of the present invention, the large exposed surface of the body-type corrosion protection structure 110 can ensure efficient corrosion protection, especially for the electrical connection structure 117. In addition, since the free end of the lead 126 is formed only by the electrical connection structures 117, 119, a correct electrical connection with the electronic environment (such as a PCB) can also be achieved.

[0088] exist Figure 4 In the embodiment, it is shown that Figure 3 A similar structure, where Figure 4 ,and Figure 3 In comparison, the relative surface portions of the electrical connection structures 117, 119 of the lead 126 are higher. From the description, Figure 4 The sensor is shown in a surface mount device (SMD) type molded package 100. In other words, the sensor type electronic device 102 is provided with a copper lead frame. Aluminum alloy anode material is added as a corrosion protection structure 110 to the electrical connection structures 117, 119 by laser welding or a cladding process.

[0089] Figure 5 Examples and Figure 1 The embodiment of the invention is different in that, according to Figure 5, the corrosion protection structure 110 is selectively covered by the corrosion protection enhancement structure 150. This is shown in the partial enlargement 182, which shows a cross-section of a portion of the lead 126. For example, the corrosion protection enhancement structure 150 can be an aluminum oxide layer formed on the aluminum layer constituting the corrosion protection structure 110. Therefore, the corrosion protection enhancement structure 150 delays the corrosion attack on the corrosion protection structure 110, thereby improving the corrosion protection of the package 100.

[0090] exist Figure 5 In an embodiment of the invention, the copper lead frame is provided with an additional less noble structure (e.g. made of aluminum or an aluminum alloy or titanium or magnesium) as anode material. This can be achieved, for example, by performing a cladding process. The formation of the sacrificial anode can already be done during the lead frame manufacturing or can be done during the packaging process. At the lead frame, the cladding material can be provided in the rolling direction of the substrate. The additional corrosion protection enhancement structure 150 is optional, but advantageous.

[0091] Figure 6 and Figure 7 A three-dimensional view of a roll 184 of a preform having a corrosion protection structure 110 and an electrical connection structure 117 for a package 100 according to an exemplary embodiment is shown. Figure 6 and Figure 7 The bimetallic strip with the corrosion protection structure 110 and the electrical connection structure 117 arranged side by side may be formed as a segment of an annular preform wound on a roll 184 .

[0092] according to Figure 6 and Figure 7 , a bimetallic strip is shown, which includes an annular strip of an electrical connection structure 117 (e.g., made of copper) and a corrosion protection structure 110 (e.g., made of aluminum) that are connected side by side and integrally. The material shown can be formed by rolling. Sections of the annular strip can be unrolled and cut from a roll 184 to form corresponding leads 126.

[0093] according to Figure 6 , the single electrical connection structure 117 and the single corrosion protection structure 110 are aligned side by side.

[0094] However, according to Figure 7 Two electrical connection structures 117 (of different widths) laterally surround a central strip of the corrosion protection structure 110 extending in parallel therebetween.

[0095] Figure 8 A schematic diagram of a vehicle 160 having a sensor package 100 according to an exemplary embodiment is shown. Thus, the sensor package 100 may be used in outdoor applications, which may be automotive applications. Figure 8, the package 100 is used as a sensor in an exhaust system 166 of a vehicle 160. The sensor may be, for example, a pressure sensor.

[0096] Thus, the sensor package 100 may form part of an exhaust system 166 and may therefore be exposed to a highly corrosive environment during use. The sensor package 100 is electrically coupled to a controller 162 which controls the operation of the vehicle 160 and in particular the operation of the electric motor 164 thereof.

[0097] Fig. 9 A schematic diagram of an offshore wind energy installation 170 with a sensor package 100 according to another exemplary embodiment is shown. More specifically, the package 100 is used here as a sensor on an offshore wind energy installation 170. Fig. 9 The offshore application places the package 100 in a highly corrosive marine environment (see reference numeral 172). The sensor package 100 according to the exemplary embodiment is installed at different parts of the wind energy device 170 for detecting certain data. As described above, when the sensor package 100 is exposed to corrosive seawater or marine air, providing corrosion protection for the sensor package 100 can significantly increase the service life of the sensor package 100.

[0098] Fig.10 A cross-sectional view of the leads 126 of the leadframe type carrier 114 of the package 100 is shown according to an exemplary embodiment.

[0099] according to Fig.10 , the package 100 includes a corrosion protection enhancement structure 150, which selectively covers the corrosion protection structure 110 and is configured to enhance the corrosion protection of the corrosion protection structure 110. For example, the corrosion protection enhancement structure 150 can be an anodic oxidation coating, a secondary corrosion protection structure made of a material configured to serve as an electron donor for the corrosion protection structure 110, a passivation coating, a phosphating coating, a cladding coating, a plasma oxidation coating, and / or a plasma ceramic conversion coating. As shown, the corrosion protection enhancement structure 150 selectively covers only the corrosion protection structure 110, but does not cover the electrical connection structure 117.

[0100] therefore, Fig.10 An embodiment is shown in which two sections of an electrical connection structure 117 (e.g. made of copper) are arranged to include between them a central section of a corrosion protection structure 110 made of aluminum or the like. Furthermore, it can be seen that the exposed surface portions of the corrosion protection structure 110 are in turn covered by a corrosion protection enhancement structure 150, e.g. a zinc or aluminum oxide layer. The corrosion protection enhancement structure 150 can be selectively applied only on the surface associated with the corrosion protection structure 110.

[0101] Fig.11 A cross-sectional view of leads 126 of a leadframe type carrier 114 of a package 100 is shown according to another exemplary embodiment.

[0102] Fig.11 The embodiment of FIG. 1 shows a substrate or body made of an electrical connection structure 117, wherein a layer of corrosion protection structure 110 is applied only to a sub-portion of the upper main surface of the layered electrical connection structure 117. Likewise, the surface of the corrosion protection structure 110 can be selectively covered by a corrosion protection enhancement structure 150, for example, by an aluminum oxide layer that can be produced as described above. From the description, the corrosion protection enhancement structure 150 can enhance the corrosion protection function of the corrosion protection structure 110.

[0103] Fig.12 A cross-sectional view of a device 130 according to an exemplary embodiment is shown. The device 130 includes a package 100 having a corrosion protection structure 110 as described above. The package 100 is mounted on and electrically connected to a mounting structure 132, which is configured here as a printed circuit board (PCB). As shown, an exposed portion of an electrical connection structure 117 of the package 100 is electrically connected to an electrical contact 134 of a plated layer in a through hole implemented as the mounting structure 132. Alternatively, the electrical connection structure 117 can also be soldered or sintered on the mounting structure 132, i.e., can be connected to the mounting structure 132 with a connecting medium such as a solder paste or a sintering paste. The corrosion protection structure 110 protects the electrical connection structure 117 from corrosion.

[0104] It should be noted that the term "comprising" does not exclude other elements or features, and "a" or "an" does not exclude a plurality. Moreover, elements described in connection with different embodiments may be combined. It should also be noted that the reference numerals should not be interpreted as limiting the scope of the claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the processes, machines, manufactures, compositions of matter, measures, methods and steps described in the specification. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, measures, methods or steps within their scope.

Claims

1. A package (100), comprising: Carrier (114); An electronic device (102) mounted on the carrier (114); and an encapsulant (106) encapsulating at least a portion of the electronic device (102) and only a portion of the carrier (114), such that another exposed portion (115) of the carrier (114) is exposed relative to the encapsulant (106); wherein the exposed portion (115) of the carrier (114) comprises exposed portions of a plurality of leads extending from the encapsulant, each lead comprising an electrical connection structure (117) and a corrosion protection structure (110), the electrical connection structure comprising a section located outside the encapsulant; ·Wherein, the corrosion protection structure (110) is strip-shaped and extends along at least a portion of at least one longitudinal edge of the lead in the extension direction of the lead, and the corrosion protection structure includes a material that inhibits corrosion of the material of the electrical connection structure, and the corrosion protection structure is selectively formed only on a sub-portion of the electrical connection structure located outside the encapsulant.

2. The package (100) according to claim 1, wherein: The corrosion protection structure (110) includes a material configured to be capable of acting as an electron donor for the electrical connection structure (117).

3. The package (100) according to claim 1 or 2, wherein: The electrical connection structure (117) comprises a material from the following group: copper, gold, silver, palladium, iron, nickel and an alloy comprising at least one of these materials.

4. The package (100) according to claim 1 or 2, wherein: The corrosion protection structure (110) comprises a material from the following group: aluminum, titanium, tantalum, niobium, magnesium, tin, zinc, and alloys comprising at least one of these materials.

5. The package (100) according to claim 1 or 2, wherein: The corrosion protection structure (110) forms the bulk of the exposed portion (115) of the carrier (114), the electrical connection structure (117) being applied to the corrosion protection structure (110) in a significantly smaller volume, i.e. not exceeding 50% of the volume of the corrosion protection structure (110).

6. The package (100) according to claim 1 or 2, wherein: The electrical connection structure (117) is made of at least one first metal, and the corrosion protection structure (110) is made of at least one second metal that inhibits corrosion of the at least one first metal.

7. The package (100) according to claim 6, wherein: The package (100) comprises one of the following features: The at least one first metal and the at least one second metal extend in parallel along at least a portion of the at least one lead (126); and The at least one second metal of the corrosion protection structure is located between two sections of the at least one first metal of the electrical connection structure along the extension direction of the at least one lead (126), and the two sections of the at least one first metal are arranged at opposite ends of the lead and are separated from each other by the at least one second metal.

8. The package (100) according to any one of claims 1 to 2 and 7, wherein: The package (100) comprises: a corrosion protection enhancement structure (150) which at least partially covers the corrosion protection structure (110) and is configured to enhance corrosion protection of the corrosion protection structure (110).

9. The package (100) according to claim 8, wherein: The corrosion protection enhancement structure (150) selectively covers the corrosion protection structure (110) but does not cover the electrical connection structure (117).

10. The package (100) according to claim 8, wherein: The corrosion protection enhancement structure (150) comprises at least one of the following group: an anodic oxidation coating, a secondary corrosion protection structure comprising a material configured to act as an electron donor for the corrosion protection structure (110), a passivation coating, a phosphating coating, a weld overlay coating, a plasma oxidation coating, and a plasma ceramic conversion coating.

11. The package (100) according to any one of claims 1 to 2, 7, 9 to 10, wherein: The carrier (114) is a lead frame including a device mounting section (124) supporting the electronic device (102) and one or more leads (126) for electrically coupling the electronic device (102) to peripheral electronic devices, wherein the corrosion protection structure (110) is formed as a part of at least one of the one or more leads (126).

12. The package (100) according to any one of claims 1 to 2, 7, 9 to 10, wherein: The package (100) is configured as a sensor package; and / or The corrosion protection structure extends from the edge of the encapsulant.

13. An apparatus (130), wherein: The device (130) comprises: A mounting structure (132); and The package (100) according to any one of claims 1 to 12, mounted on the mounting structure (132) such that the electrical connection structure (117) is electrically connected to the mounting structure (132).

14. A method for manufacturing a package (100) according to any one of claims 1 to 12, wherein: The method comprises: Mounting the electronic device (102) on a carrier (114); encapsulating at least a portion of the electronic device (102) and only a portion of the carrier (114) by an encapsulant (106) such that another exposed portion (115) of the carrier (114) is exposed relative to the encapsulant (106); and forming the exposed portion (115) of the carrier (114) to have an electrical connection structure (117) and a corrosion protection structure (110), so that the electrical connection structure (117) is selectively formed only on a sub-portion of the corrosion protection structure (110), or so that the corrosion protection structure (110) is selectively formed only on a sub-portion of the electrical connection structure (117) located outside the encapsulant (106); Wherein, the corrosion protection structure (110) is strip-shaped.

15. The method according to claim 14, wherein: The method includes forming the connected electrical connection structure (117) and the corrosion protection structure (110) by at least one of the following group: providing a bimetallic strip, laser welding, and selective plating.

16. The method according to claim 14 or 15, wherein: The method includes forming a corrosion protection enhancement structure (150) that at least partially covers the corrosion protection structure (110) and is configured to enhance corrosion protection of the corrosion protection structure (110).

17. The method according to claim 16, wherein: The method includes forming the corrosion protection enhancement structure (150) by at least one of the following: anodizing, forming a secondary corrosion protection structure made of a material configured to function as an electron donor for the corrosion protection structure (110), passivating, phosphating, cladding, plasma oxidation, and performing a plasma ceramic conversion.

18. A method of using a package (100) according to any one of claims 1 to 12 for outdoor applications in a corrosive environment.

19. The method according to claim 18, wherein: The outdoor application is an automotive application.

20. The method according to claim 18, wherein: The outdoor application is a wind energy installation application.

Images