Package with selective corrosion protection of an electrical connection structure

Abstract

Having one package (100): • a carrier (114); • an electronic component (102) which is mounted on the carrier (114); and • an encapsulation (106) which encapsulates at least part of the electronic component (102) and only part of the carrier (114), such that another exposed part (115) of the carrier (114) is exposed in relation to the encapsulation (106); • wherein the exposed part (115) of the support (114) has an electrical connection structure (117) and a corrosion protection structure (110); • wherein the electrical connection structure (117) is selectively formed only on a subsection of the corrosion protection structure (110), or wherein the corrosion protection structure (110) is selectively formed only on a subsection of the electrical connection structure (117), outside the encapsulation (106); and • wherein the support (114) has at least one metallic conductor (126) which has the electrical connection structure (117) made of at least one first metal, and which has the corrosion protection structure (110) made of at least one second metal which inhibits corrosion of the at least one first metal; • wherein the corrosion protection structure (110) is strip-shaped; wherein the electrical connection structure (117) and the corrosion protection structure (110) are made of a bimetallic strip formed by rolling.

Description

background

[0001] The present invention relates to a package, an arrangement, a method for producing a package and a method for using it.

[0002] A package may include an electronic component, such as a semiconductor chip, mounted on a carrier, such as a lead frame. Packages may be embodied as an encapsulated electronic component mounted on a carrier with electrical connections extending from the encapsulation and coupled to an electronic peripheral.

[0003] However, packages have a limited lifespan when used under harsh conditions.

[0004] DE 10 2006 032 074 B3 shows a package with corrosion-protected connecting wires. Summary

[0005] There may be a need for a package with extended lifetime, even when used under harsh conditions.

[0006] According to an exemplary embodiment, a package is provided comprising a carrier, an electronic component mounted on the carrier, and an encapsulation encapsulating at least a portion of the electronic component and only a portion of the carrier such that another exposed portion of the carrier is exposed with respect to the encapsulation, wherein the exposed portion of the carrier comprises an electrical connection structure and a corrosion protection structure, and wherein one of the electrical connection structure and the corrosion protection structure is selectively formed only on a portion of the other of the electrical connection structure and the corrosion protection structure outside the encapsulation.

[0007] According to another exemplary embodiment, an assembly is provided which comprises a mounting structure (e.g., a printed circuit board, PCB) and a package having the aforementioned features and mounted on the mounting structure such that the electrical connection structure is electrically connected to the mounting structure.

[0008] According to yet another exemplary embodiment, a method for manufacturing a package is provided, the method comprising mounting an electronic component on a carrier, encapsulating at least a part of the electronic component and only a part of the carrier by means of an encapsulation such that another exposed part of the carrier is exposed with respect to the encapsulation, and forming the exposed part of the carrier with an electrical connection structure and with a corrosion protection structure such that one of the electrical connection structure and the corrosion protection structure is selectively formed only on a partial section of the other of the electrical connection structure and the corrosion protection structure outside the encapsulation.

[0009] According to yet another exemplary embodiment, a package having the above-mentioned features is used for outdoor application in a corrosive environment.

[0010] According to an exemplary embodiment, a package is provided with an encapsulated electronic component on a carrier, the carrier extending with an exposed portion thereof partially beyond the encapsulation. The exposed portion of the carrier has an electrical connection structure for electrically connecting the package to an electronic environment and has a corrosion protection structure for protecting the electrical connection structure against corrosion, i.e., for inhibiting, preventing, or even suppressing corrosion of the electrical connection structure.

[0011] The electrical connection structure and the corrosion protection structure are partially formed on top of each other to be spatially close to each other, thereby achieving effective corrosion protection of the electrical connection structure. However, by selectively covering only a portion of one of the structures with the other structure, it can be ensured that both the corrosion protection structure and the electrical connection structure remain exposed to the environment outside the encapsulation. This can simplify and improve the electrical connectivity of the package with respect to the electronic periphery. Thus, the electrical reliability of the package can be significantly improved while simultaneously providing effective corrosion protection.

[0012] As a result, a corrosion-resistant package can be provided. In particular, a semiconductor package can be provided with metallic conductors made of a first metal, which function as an electrical connection structure and are in electrical contact with a second metal, which functions as an electron donor to the first metal, thus acting as a corrosion protection structure. Description of further exemplary embodiments

[0013] Further exemplary embodiments of the package, arrangement and methods are explained below.

[0014] In the context of the present application, the term "package" may, in particular, refer to an electronic device comprising one or more electronic components mounted on a carrier and optionally packaged using an encapsulation. Furthermore, one or more electrically conductive contact elements (e.g., bonding wires or terminals) may optionally be implemented in a package, for example, for electrically coupling the electronic component to the carrier.

[0015] In the context of the present application, the term "carrier" may, in particular, refer to a (preferably, but not necessarily, electrically conductive) support structure that serves as a mechanical support for the one or more electronic components and that may also contribute to the electrical connection between the electronic component(s) and the periphery of the package. In other words, the carrier may fulfill a mechanical support function and an electrical connection function.

[0016] In the context of the present application, the term "electronic component" may in particular encompass a semiconductor chip (in particular a power semiconductor chip), an active electronic device (e.g., a transistor), a passive electronic device (e.g., a capacitor, an inductance, or an ohmic resistor), a sensor (e.g., a microphone, a light sensor, or a gas sensor), an actuator (e.g., a loudspeaker), and a microelectromechanical system (MEMS). In particular, the electronic component may be a semiconductor chip having at least one integrated circuit element (e.g., a diode or a transistor) in a surface portion thereof. The electronic component may be a bare die or may be pre-packaged or encapsulated.

[0017] In the context of the present application, the term "encapsulation" may, in particular, refer to a substantially electrically insulating and preferably thermally conductive material that surrounds (e.g., hermetically surrounds) an electronic component and optionally a portion of a carrier to provide mechanical protection, electrical insulation, and optionally contribute to heat dissipation during operation. Such an encapsulation may, for example, be a mold compound. Encapsulation by means of a molding process may, for example, involve injection molding or transfer molding.

[0018] In the context of the present application, the term "corrosion protection structure" can, in particular, refer to a physical body made of a material that protects another material of the exposed support part, i.e., the electrical connection structure, against corrosion. Such corrosion protection can be due to the fact that the corrosion protection structure is chemically more likely to release electrons during a corrosion process than the material of the electrical connection structure. For example, the corrosion protection structure can be made of a less noble metal or alloy than another metal or alloy of the electrical connection structure.

[0019] In the context of the present application, the term "electrical connection structure" may, in particular, refer to a portion of an encapsulation-outer conductor portion of the exposed part of the carrier, which encapsulation-outer conductor portion is configured and intended to be electrically connected to an electronic periphery, for example, 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 opening of the mounting structure. In particular, the electrical connection structure may serve to establish an electrical connection of the package with respect to an electronic environment, which electrical connection function should not be impaired by corrosion.

[0020] In the context of the present application, the term "a structure selectively formed only on a portion of another structure" may specifically mean that the structure covers a portion of the other structure, but a remaining portion of the other structure remains 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 may leave another surface portion of the corrosion protection structure exposed. In another alternative, the corrosion protection structure is formed on a portion of the surface of the electrical connection structure, but keeps another portion of the electrical connection structure exposed. Thus, in one embodiment, the corrosion protection structure is selectively formed only on a portion of the electrical connection structure outside the encapsulation, see, for example,Fig. 1. In another embodiment, the electrical connection structure is selectively formed only on a portion of the corrosion protection structure outside the encapsulation, see for example Fig. 3. This measure can ensure that both the electrical connection structure and the corrosion protection structure, which form part of an encapsulation-exposed support section, can fulfil their function without deteriorating or weakening the function due to an undesired complete coverage of the respective structure with the other structure.

[0021] In one embodiment, the corrosion protection structure is made of a material configured to function as an electron donor for the electrical connection structure. In other words, a material of the corrosion protection structure may be a less noble metal or alloy than another metal or alloy of the electrical connection structure. The electronegativity of the material of the electrical connection structure may be higher than the electronegativity of the material of the corrosion protection structure. In the event of a corrosive attack, the corrosion protection structure is corroded instead of the electrical connection structure.

[0022] In one embodiment, the electrical connection structure comprises or consists of a material from the group consisting of copper, gold, silver, palladium, iron, nickel, and alloys comprising at least one of these materials. However, other materials for the electrical connection structure are possible. It is preferred to manufacture the electrical connection structure from copper, as this material is highly compatible with packaging technology.

[0023] In one embodiment, the corrosion protection structure comprises or consists of a material from the group consisting of aluminum, titanium, tantalum, niobium, magnesium, tin, zinc, and alloys comprising at least one of these materials. However, other materials for the corrosion protection structure are possible. A preferred material for the corrosion protection structure, for example, may be aluminum, as this material is highly compatible with package technology.

[0024] In one embodiment, the corrosion protection structure is strip-shaped. A strip-shaped corrosion protection structure can, for example, have a rectangular shape. This has the advantage that the corrosion protection structure is provided along a substantial extent, i.e., the entire extent of the strip.

[0025] Furthermore, a strip-shaped corrosion protection structure can be produced based on a bimetallic strip, which can be provided, for example, on a roll (see Fig. 6 and Fig. 7).

[0026] In one embodiment, the electrical connection structure forms a bulk body or main body of the exposed portion of the carrier, and the corrosion protection structure is applied to the electrical connection structure with a significantly smaller volume, in particular with no more than 50% of the volume of the electrical connection structure. Clearly, the electrical connection structure can thus form the base structure, which provides a surface portion on which the corrosion protection structure can be applied, for example, deposited. This measure can ensure a low-resistance and high-performance electrical connection.

[0027] In another embodiment, the corrosion protection structure forms a bulk body of the exposed portion of the carrier, and the electrical connection structure is 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 can form the base body of the encapsulation-outer carrier portion, which provides a surface portion onto which material of the electrical connection structure can be applied, for example, deposited. Such an embodiment may be preferred in the case of extremely strong corrosive atmospheres or corrosive attacks.

[0028] In one embodiment, the carrier has at least one metallic conductor. This at least one metallic conductor can have the electrical connection structure made of at least one first metal and can have the corrosion protection structure made of at least one second metal, which prevents the at least one first metal from corroding. In particular, a plurality of conductors can be provided, which extend, for example, parallel to one another. In such an embodiment, the carrier can be, for example, a lead frame.

[0029] In one embodiment, the at least one first metal and the at least one second metal extend parallel along a part of the at least one conductor or even along the entire at least one conductor. 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 extend substantially along the entire encapsulation-outer portion of the conductor (see, for example, Fig. 1) or only along a part of it (see for example Fig. 2). In the former embodiment, extremely efficient corrosion protection can be achieved. In the latter embodiment, in particular, an end portion of the respective conductor can be provided entirely by the first metal, thereby promoting a good electrical connection along a sufficiently large connection surface. In the former embodiment, extremely efficient corrosion protection can be achieved.

[0030] In one embodiment, the at least one second metal extends in an extension direction of the at least one conductor between two sections of the at least one first metal. Such an embodiment is described, for example, in Fig. 3 and Fig. 4. For example, opposite end portions of the respective conductor can be provided by means of the (particularly more noble) first metal, thereby enabling a good connection of the package to an electronic environment and an encapsulated electronic component to the conductor, for example by means of wire bonding. A region in between can be formed by means of the (particularly less noble) second metal, thereby providing extremely efficient corrosion protection. An electrical signal or current can also be conducted along both the first metal and the second metal.

[0031] In a preferred embodiment, the package comprises a corrosion protection-enhancing structure that at least partially covers the corrosion protection structure and is configured to enhance the corrosion protection of the corrosion protection structure. In a highly advantageous manner, the corrosion protection structure can in turn be partially or completely covered with a corrosion protection-enhancing structure to further increase the corrosion protection capability of the package. For example, such a corrosion protection-enhancing structure can be a coating of the corrosion protection structure that enhances the corrosion protection capability of the corrosion protection structure and / or that protects the corrosion protection structure itself from corrosion. As a result, the overall corrosion protection of the electrical connection structure can be significantly enhanced.

[0032] In one embodiment, the corrosion protection enhancing structure comprises at least one of the group consisting of an anodization coating, a second-stage corrosion protection structure, a material configured to function as an electron donor for the corrosion protection structure, a passivation coating, a phosphating coating, a build-up welding coating, a plasma oxidation coating, and a plasma-ceramic conversion coating. However, other methods for forming the corrosion protection enhancing structure are also possible.

[0033] In one embodiment, the corrosion protection reinforcing structure selectively covers the corrosion protection structure but not the electrical connection structure. Thus, the electrical connection structure can be free of the corrosion protection reinforcing structure (which can thus be selectively applied only to the corrosion protection structure) to avoid any undesirable influence of the corrosion protection reinforcing structure on the electrical connection functionality 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 reinforcing structure.

[0034] In one embodiment, the carrier comprises a lead frame. In particular, such a lead frame may comprise a component mounting section (in particular a die pad) that supports the electronic component and one or more conductors for electrically coupling the electronic component to an electronic peripheral. Further in particular, the corrosion protection structure may be formed on and / or as part of at least one of the one or more conductors. For example, such a lead frame may comprise the electrical connection structure made of copper and a corrosion protection structure made of aluminum.

[0035] In one embodiment, the leadframe may be a plate-like metallic structure, which may be patterned to form one or more die pads or mounting sections for mounting the one or more electronic components of the package and one or more conductor sections for electrically connecting the package to an electronic environment when the electronic component(s) is / are mounted on the leadframe. In one embodiment, the leadframe may be a metal plate (in particular made of copper), which may be patterned, for example, by stamping or etching. Forming the chip carrier as a leadframe is a cost-effective and mechanically and electrically advantageous configuration in which a low-resistance connection of the at least one electronic component can be combined with a robust support capability of the leadframe.Furthermore, a leadframe can contribute to the thermal conductivity of the package and can dissipate heat generated during operation of the electronic component(s) as a result of the high thermal conductivity of the metallic (particularly copper) material of the leadframe. A leadframe can, for example, comprise aluminum and / or copper. In the context of the present application, the term "die pad" can in particular refer to a portion of a leadframe shaped and dimensioned to receive an electronic component, for example a semiconductor chip. Accordingly, the surface area of ​​the die pad is typically flat and planar and sufficiently large to completely accommodate the chip or die thereon.In contrast, the term “lead” may in particular refer to another portion of a lead frame, which may extend at least partially over an encapsulation (if present) and serves as a connecting element to an electronic periphery of the package. For example, it is possible that one or more terminals of the electronic component mounted on the die pad is or are electrically connected to a corresponding one of the conductors, for example by means of a clamp, a bonding wire, or a bonding tape. For example, it is possible that the die pad is encapsulated and the conductors are partially or completely exposed with respect to an encapsulation. It is also possible that the die pad forms a central portion of a lead frame-like carrier, whereas the conductors may form a peripheral portion of the lead frame.Both the die pads and the conductors can be made at least partially of a metallic material. In particular, the carrier can be a partially or completely metallic structure.

[0036] In another embodiment, the carrier comprises a stack comprising a central electrically insulating and thermally conductive layer (e.g., a ceramic layer) covered on both opposite main surfaces by a respective electrically conductive layer (e.g., a copper layer or an aluminum layer, wherein the respective electrically conductive layer may be a continuous or a structured layer). In particular, the carrier may be embodied as a Direct Copper Bonding (DCB) substrate or a Direct Aluminum Bonding (DAB) substrate. In such embodiments, one of the electrically conductive layers may be covered with another metal that is either more or less noble than the material of the metallic layer.As a result, the metallic layer can serve as the electrical connection structure or as the corrosion protection structure, wherein a corrosion protection structure or an electrical connection structure is selectively applied only on a partial surface of the metallic layer.

[0037] In one embodiment, the electronic component is mounted on the carrier using at least one of the group consisting of a solder structure, a sintered structure, a welded structure, and an adhesive structure. However, other connection methods are also possible.

[0038] In one embodiment, the carrier is configured as a bulk structure for mechanically supporting the mounted electronic component and / or for electrically contacting the mounted electronic component. Accordingly, the carrier can fulfill a dual function. On the one hand, the carrier can support the electronic component (e.g., on a die pad), and additionally, the carrier can electrically connect the mounted electronic component to the electronic environment of the package (e.g., via an electrically conductive connecting element, such as a bond wire or a clamp).

[0039] In one embodiment, the connected electrical connection structure and the corrosion protection structure can be formed by providing a bimetallic strip, by laser welding, or by selective plating. For example, a bimetallic strip can be formed by rolling, thereby joining two different metals (in particular, a more noble metal and a less noble metal). Such a bimetallic strip can, in particular, be formed as a section of an endless preform of the carrier conductors, which is wound onto a roll. This enables efficient production of the conductors that form part of a carrier for providing the connected electrical connection structure and corrosion protection structure.Alternatively, it is possible to weld a first metal or alloy together with a second metal or alloy by laser welding to thereby obtain the connected electrical connection structure and the corrosion protection structure. Laser welding is particularly advantageous in this regard. Selective plating of the electrical connection structure onto the corrosion protection structure, or vice versa, may also be possible. However, care should be taken to ensure that the plating procedure is only selective, i.e., that one of the structures is only partially covered by the other, leaving exposed surface portions of both the electrical connection structure and the corrosion protection structure.For example, selective plating can be accomplished by covering a surface portion of the respective structure that is not to be plated with a protective material and removing the protective material after plating is completed.

[0040] In one embodiment, the package is configured as a sensor package. Due to the nature of their function, sensor packages are often exposed to a highly corrosive environment. Thus, sensor components or sensor chips, as an example of the electronic component of the package, must be arranged in a position with a highly corrosive influence in order to fulfill their sensing task. Therefore, providing a corrosion protection structure, which in particular provides corrosion protection on an encapsulation-outer conductor portion of a carrier of the package, can be extremely advantageous for sensor applications.

[0041] In one embodiment, the package can be used for an outdoor application, which is an automotive application. In particular, using the package as a sensor in a vehicle's exhaust system can be advantageous. Automotive applications typically involve a highly corrosive environment. Therefore, the advantages achieved by the package's corrosion protection structure are particularly pronounced in the automotive sector.

[0042] In another embodiment, the outdoor application is a wind turbine application, in particular, a use of the package as a sensor on an offshore wind turbine. The field of wind turbines, especially when used as an offshore wind turbine, also presents an extremely corrosive environment. Both seawater and sea air contain a high salt concentration and can therefore act as an extremely corrosive environment. Providing a package (in particular, a sensor package) for wind turbine applications with a corrosion protection structure on an encapsulated outer conductor section can therefore be extremely advantageous.

[0043] In one embodiment, the package comprises a plurality of electronic components mounted on the carrier. Thus, the package may comprise one or more electronic components (e.g., at least one passive component, such as a capacitor, and at least one active component, such as a semiconductor chip).

[0044] In one embodiment, the encapsulation may comprise a mold, in particular a plastic mold. For example, a correspondingly encapsulated body (in particular the electronic component with the carrier) may be provided by placing the body or bodies between an upper mold and a lower mold and injecting a liquid molding material into it. After the molding material has cured, the formation of the encapsulation is complete. If desired, the molded body may be filled with particles that improve its properties, for example, its heat dissipation properties. In other exemplary embodiments, the encapsulation may also be a laminate or an injection-molded part (casting compound).

[0045] In one embodiment, the package comprises an electrically conductive connection structure that electrically connects the mounted electronic component to the carrier. For example, the electrically conductive connection structure may comprise at least one of the group consisting of a clamp, a wire bond, and a tape bond. A clamp may be a three-dimensionally curved plate-like connecting element having two planar sections that are to be connected to an upper main surface of the respective electronic component and an upper main surface of the carrier, wherein the two planar sections terminate in an inclined connection section.As an alternative to such a terminal, it is possible to use a wire bond or ribbon bond, which is a flexible electrically conductive wire- or ribbon-shaped body having one end portion connected to the upper main surface of the respective electronic component and an opposite other end portion electrically connected to the carrier.

[0046] In one embodiment, the at least one electronic component comprises at least one from the group consisting of a controller circuit, a driver circuit, and a power semiconductor circuit. All of these circuits can be integrated into a semiconductor chip or be separate in different chips. For example, a corresponding power semiconductor application can be realized using the chip(s), wherein integrated circuit elements of such a power semiconductor chip can comprise at least one transistor (in particular a MOSFET, metal-oxide semiconductor field-effect transistor), at least one diode, etc. In particular, circuits can be produced which fulfill a half-bridge function, a full-bridge function, etc.

[0047] A semiconductor substrate, i.e., a silicon substrate, can be used as the substrate or wafer for the semiconductor chips. Alternatively, a silicon oxide or other insulating substrate can be provided. It is also possible to implement a germanium substrate or a III-V semiconductor material. For example, exemplary embodiments can be implemented using GaN or SiC technology.

[0048] The foregoing and other objects, features and advantages of the present invention will become apparent from the following description and the 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

[0049] The accompanying drawings, which are included to provide a further understanding of exemplary embodiments of the invention and which constitute a part of the specification, illustrate exemplary embodiments of the invention.

[0050] In the drawings: Fig. 1 to Fig. 5 show three-dimensional views of packages with a corrosion protection structure according to exemplary embodiments. Fig. 6 and Fig. 7 show three-dimensional views of rolls with a preform of combined electrical connection structures and corrosion protection structures for packages according to exemplary embodiments. Fig. 8 shows a schematic view of a vehicle with a package according to an exemplary embodiment. Fig. 9 shows a schematic view of an offshore wind turbine with packages according to an exemplary embodiment. Fig. 10 shows a cross-sectional view of a lead of a lead frame carrier of a package according to an exemplary embodiment. Fig. 11 shows a cross-sectional view of a lead of a lead frame carrier of a package according to another exemplary embodiment. Fig. 12 shows a cross-sectional view of an assembly according to an exemplary embodiment, including a package mounted on and electrically connected to a mounting structure. Detailed description of exemplary embodiments

[0051] The representation in the drawing is schematic and not to scale.

[0052] Before exemplary embodiments are described in more detail with reference to the figures, some general considerations are summarized on the basis of which exemplary embodiments were developed.

[0053] In many applications, integrated circuits and electronic systems are exposed to moisture or corrosive atmospheres. There is a risk of damage to metallic structures or contacts of the integrated circuit or the surrounding system. Examples include sensors in a vehicle's anti-lock braking system (which may be exposed to salt spray), power electronics devices in trains (which may be exposed to moisture), pressure sensors in automobile exhaust systems, etc.

[0054] Protecting against attack by corrosive media is difficult. With the help of protective coatings, some improvement is possible. However, due to the fact that almost every organic material has a certain moisture absorption potential, even aqueous corrosive media are easily absorbed by these materials and cannot effectively protect integrated circuits over a long period of time.

[0055] According to an exemplary embodiment, a semiconductor package is provided with metallic conductors made of a first metal that are in electrical contact with a second metal that serves as an electron donor (or acceptor) to the first metal. Thus, the second metal can act as a sacrificial anode for the first metal and can provide efficient corrosion protection for the first metal. Thus, exemplary embodiments combine the package with a sacrificial metal that corrodes faster than the metals in the package and use it as a sacrificial anode, taking into account the specific requirements of the semiconductors when exposed to corrosive atmospheres.If a user exposes an electronic system to moisture or corrosive atmospheres, providing a corrosion protection structure can help the user by providing a packaged integrated circuit with built-in corrosion protection. This protects the package itself, as well as the contact and immediate environment of the package in a more complex electronic system.

[0056] In one embodiment, a corrosion-resistant sensor can be manufactured by providing a galvanic anode. In one application, this can suppress corrosion of pressure sensors in the exhaust line or exhaust system of a vehicle due to nitric acid and / or other corrosive media.

[0057] A problem with packages, especially sensor packages, is the corrosion of (for example magnetic) sensors due to water, salt or other corrosive media.

[0058] To overcome such disadvantages, exemplary embodiments add a sacrificial anode to the critical sensor packages. Suitable material combinations between such a corrosion protection structure and an electrical connection structure are generally possible according to the electrochemical series. The corrosion protection structure is typically made of a less noble material than the electrical connection structure.

[0059] In various embodiments, cathodic corrosion protection or the provision of a sacrificial anode is also possible. In particular, a metal combination of less noble and more noble metals or layers is possible. In a leadframe design, i.e., in which the carrier is a leadframe, this can be achieved to protect functional areas from corrosion attack by providing a sacrificial anode or cathodic corrosion protection.

[0060] A non-noble metal can be used as a sacrificial anode, for example made of aluminum, titanium, tantalum, niobium, magnesium or alloys thereof.

[0061] In particular, a combination of a copper lead frame and metals or alloys of one or more of the above-mentioned anode materials may be advantageous.

[0062] In another embodiment, an aluminum or aluminum alloy leadframe may be provided with a partial copper deposition or an additional copper leadframe. In addition to or as an alternative to providing copper, other precious metals such as gold, silver, palladium, etc. may also be used.

[0063] In a preferred embodiment, the corrosion protection structure can be covered by a corrosion protection-enhancing structure that enhances the corrosion protection function of the corrosion protection structure. Such a corrosion protection-enhancing structure can be applied in the form of cathodic corrosion protection or by providing a sacrificial anode, etc. Methods and materials of such a corrosion protection-enhancing structure can be as follows:

[0064] In a first embodiment, a corrosion protection-enhancing structure can be formed by anodizing a sacrificial anode. Such processing can be possible, in particular, based on aluminum or alloys (e.g., an aluminum alloy or brass) in combination with a copper leadframe and can be applied with minimal effort.

[0065] Aluminum itself can be anodized and thus converted into aluminum oxide. This also protects the actual sacrificial anode, i.e., the corrosion protection structure. Thus, the sacrificial anode, which forms the corrosion protection structure, can be oxidized at one surface. The thicker the oxidized corrosion protection structure on the surface, the longer a corrosion attack on the corrosion protection structure is delayed by the corrosion protection-reinforcing structure.

[0066] In a second embodiment, a corrosion protection-enhancing structure can be formed by means of a second-stage corrosion protection structure, i.e., a less noble coating than the underlying corrosion protection structure. Providing a second-stage corrosion protection structure (e.g., a zinc coating) as a corrosion protection-enhancing structure can be an inorganic or organic protective layer (e.g., made of iron) on the corrosion protection structure.

[0067] In a third embodiment, a corrosion protection-enhancing structure can be formed by means of a sealing layer. In particular, it may be possible to enhance the corrosion protection of the sacrificial anode itself. Providing a sealing layer that seals the corrosion protection structure against corrosive attack as a corrosion protection-enhancing structure can also improve the overall corrosion protection function.

[0068] In a fourth embodiment, a corrosion protection-enhancing structure can be formed by phosphating, i.e., the formation of a phosphating layer. In particular, it may be possible to enhance the corrosion protection of a sacrificial anode itself by means of an additional zinc deposition to further enhance corrosion protection. For example, wire bonding and a user-specific configuration of a functional region can be combined with such a process to apply a noble metal (e.g., silver, copper, gold, palladium, etc.). Such a process can advantageously act selectively only on aluminum. The phosphating layer can serve as a temporary corrosion layer formed only on the less noble corrosion protection structure and not on the electrical connection structure, which is more noble.Thus, selective corrosion protection can be formed, for example on a bimetallic strip.

[0069] In a fifth embodiment, a corrosion protection-enhancing structure can be formed by build-up welding or cladding. Many metals can be applied as a sacrificial layer to copper itself, as well as to aluminum or alloys (a sacrificial anode as a corrosion protection structure) to enhance corrosion protection there. In particular, it may be possible to apply one or more functional layers for wire bonding and user-specific applications, etc. Build-up welding can form a weld by applying a welding material that deposits an even less noble material than the material of the corrosion protection structure, which in turn is less noble than the material of the electrical connection structure.

[0070] In a sixth embodiment, a corrosion protection-enhancing structure can be formed by plasma oxidation on aluminum or the like. Thus, it may be possible to enhance the corrosion protection of the sacrificial anode or the corrosion protection structure itself by plasma oxidation. Wire bonding and the configuration of a user-specific functional region can be combined with such a process to apply a noble metal (e.g., silver, copper, gold, palladium, etc.). Such a process can work selectively only on aluminum. Consequently, the material of the corrosion protection structure with the lower nobility can be treated with a plasma to thereby enhance the corrosion resistance of the electrical connection structure by enhancing the corrosion protection function of the corrosion protection structure.The modified surface of the corrosion protection structure as a result of plasma oxidation can then form the corrosion protection reinforcing structure.

[0071] In a seventh embodiment, a corrosion protection-enhancing structure can be formed using a plasma ceramic conversion layer. This can enhance the corrosion protection of the sacrificial anode or of the corrosion protection structure itself, such as an aluminum anode. Again, the wire bonding and the formation of the user-specific functional region can be combined with such a process to apply a noble metal (e.g., silver, copper, gold, palladium, etc.). Such a process can also advantageously function selectively only on aluminum. A plasma ceramic conversion layer can be a separate nano-ceramic layer covering the sacrificial anode in the form of the 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, such a plasma ceramic conversion layer may have a high ductility, ie it may not be brittle, which also improves the mechanical properties of the package.

[0072] Fig. 1 to Fig. 5 show three-dimensional views of packages 100 with a corrosion protection structure 110 according to exemplary embodiments.

[0073] Referring to Fig. 1 shows a semiconductor sensor package 100 comprising a leadframe-like carrier 114, an electronic component 102 (for example, a semiconductor chip, in particular a sensor chip) mounted on the carrier 114, and a molded-body encapsulation 106 encapsulating the electronic component 102 and only a portion of the carrier 114. Due to this partial encapsulation, another exposed portion 115 of the carrier 114—also referred to as the encapsulation-outer carrier portion—is exposed with respect to the encapsulation 106 and thus extends beyond the encapsulation 106.

[0074] As shown, the exposed portion 115 of the carrier 114 includes an electrical connection structure 117 configured to establish an electrical connection (e.g., a solder connection) between the package 100 and an electronic peripheral, such as a printed circuit board (PCB, not shown). Furthermore, 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 portion of the electrical connection structure 117 outside the encapsulation 106. As a result, a portion of the electrical connection structure 117 remains exposed to the environment, significantly improving the quality of an electrically conductive connection between the electrical connection structure 117 and the electronic peripheral.To fulfill its anti-corrosive function, the anti-corrosive structure 110 is also exposed to the environment and is made of a material configured to function as an electron donor for the electrical connection structure 117 during corrosive attack. For example, the electrical connection structure 117 comprises or consists of copper. In contrast, the anti-corrosive structure 110 comprises or consists of aluminum, which is less noble than copper.

[0075] As shown, the leadframe-like carrier 114 has a plurality of parallel-extending metallic conductors 126, each having 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 and therefore prevents the copper from corroding. As shown, each electrical connection structure 117 and each corrosion protection structure 110 of each conductor 126 extend parallel to each other along the respective encapsulation outer portion of the respective conductor 126.

[0076] As already noted, the carrier 114 is embodied as a lead frame having a die pad as a component mounting section 124 that supports the electronic component 102 and three parallel conductors 126 for electrically coupling the electronic component 102 to the electronic peripherals. As already noted, each corrosion protection structure 110 is formed as a part of a respective one of the plurality of conductors 126. As also shown in Fig. 1, each of the corrosion protection structures 110 is arranged outside the encapsulation 106.

[0077] According to Fig. 1, the electrical connection structure 117 forms a bulk body of the exposed portion 115 of the carrier 114, and the corrosion protection structure 110 is applied only to a partial portion of the surface of the electrical connection structure 117 with a significantly smaller volume compared to the volume of the electrical connection structure 117. For example, each corrosion protection structure 110 can be applied to the associated electrical connection structure 117 by means of selective plating (or alternatively based on a bimetallic strip, as in Fig. 6 and Fig. 7, or by laser welding).

[0078] Thus, Fig. 1, that a respective sacrificial anode material, as a corrosion protection structure 110, is added to the respective IC (integrated circuit) package metal in the form of the electrical connection structure 117.

[0079] Thus, a conventional lead frame, for example made of copper, can be used as the carrier 114. An additional sacrificial anode metal, for example zinc or aluminum, can be added to each conductor 126 of the carrier 114 to provide a corresponding corrosion protection structure 110.

[0080] According to Fig. 1, the upper main surface of the electronic component 102 is electrically connected to the conductors 126 of the leadframe-like carrier 114 by means of bonding wires 180. As an alternative to the bonding wires 180, it is also possible to use another electrically conductive connecting element for connecting the electronic component 102 to the conductors 126 of the carrier 114 (e.g., terminals or bonding strips).

[0081] The embodiment of Fig. 2 differs from the embodiment of Fig. 1 in that according to Fig. 2, the corrosion protection structure 110 of each conductor 126 extends only along a partial section of the encapsulation-outer conductor section of the carrier 114. Thus, free ends of the conductors 126 are formed exclusively by the material of the electrical connection structure 117, not by the material of the corrosion protection structure 110. This simplifies and improves the electrical connectivity of the conductors 116 to an electronic environment (e.g., a printed circuit board or other mounting base).

[0082] Referring to Fig. 3, the corrosion protection structure 110 forms an aluminum bulk body of the conductors 126 of the carrier 114. The copper material of the electrical connection structures 117, 119 is applied only to two spaced-apart sections of the corrosion protection structure 110 with a significantly smaller volume compared to the volume of the corrosion protection structure 110. The electrical connection structure 117 is exposed and extends beyond the encapsulation 106, whereas the electrical connection structure 119 is encapsulated in the encapsulation 106. Thus, the corrosion protection structure 110 of each conductor 126 extends in an extension direction of the respective conductor 126 between two precious metal sections of the electrical connection structures 117, 119. In other words, the embodiment of Fig. 3 sections of precious metals to a sacrificial base material. Thus, the embodiment of Fig. 3 can be manufactured based on a conventional lead frame (e.g., made of aluminum), onto which an additional precious metal, e.g., copper, is selectively deposited to form the electrical connection structures 117, 119. During chemical stress, the sacrificial bulk metal of the corrosion protection structure 110 is attacked, while the precious copper material of the electrical contact structures 117, 119 remains stable at the electrical contact positions. As a result, the electrical contacts of the electrical contact structures 117, 119 are protected.

[0083] In the embodiment of Fig. 3, a large exposed surface of the bulk-type corrosion protection structure 110 can ensure extremely efficient corrosion protection, particularly of the electrical connection structure 117. Furthermore, since the free ends of the conductors 126 are formed only by means of the electrical connection structures 117, 119, a good electrical connection to an electronic environment (e.g., a PCB) is also enabled.

[0084] In the embodiment of Fig. 4 is a similar structure as in Fig. 3, however, the relative surface sections of the electrical connection structures 117, 119 of the conductors 126 are shown in Fig. 4 compared to Fig. 3 are larger. Fig. 4 shows a sensor in a surface-mounted device (SMD)-type molded body package 100. In other words, a sensor-type electronic component 102 is provided with a copper lead frame. An aluminum alloy anode material, as corrosion protection structures 110, is added to the electrical contact structures 117, 119 by laser welding or a cladding process.

[0085] The embodiment of Fig. 5 differs from the embodiment of Fig. 1 in that according to Fig. 5, the corrosion protection structure 110 is selectively covered by a corrosion protection enhancing structure 150. This is illustrated in detail 182, which shows a cross-section of a portion of the conductor 126. For example, the corrosion protection enhancing structure 150 may be an aluminum oxide layer formed on the aluminum layer constituting the corrosion protection structure 110. Thus, the corrosion protection enhancing structure 150 delays corrosion attack on the corrosion protection structure 110 and thus improves the corrosion protection of the package 100.

[0086] In the embodiment of Fig. 5, a copper leadframe is provided with additional less noble structures (e.g., made of aluminum or an aluminum alloy, or titanium or magnesium) as anode material. For example, this can be accomplished by performing an overplating process. The formation of the sacrificial anode can already occur during the leadframe manufacturing process or can occur during a packaging process. Overplating material can be provided on the leadframe along a base material rolling direction. The additional corrosion protection-enhancing structure 150 is optional but advantageous.

[0087] Fig. 6 and Fig. 7 show three-dimensional views of rollers 184 with a preform of the corrosion protection structures 110 and the electrical connection structures 117 for packages 100 according to exemplary embodiments. Thus, the bimetallic strips of the corrosion protection structure 110, which are arranged next to the electrical connection structure 117 according to Fig. 6 and Fig. 7 is arranged, may be formed as a section of an endless preform which is rolled up on a roll 184.

[0088] According to Fig. 6 and Fig. 7 shows bimetallic strips comprising, juxtaposed and integrally connected, a continuous strip of an electrical connection structure 117 (e.g., made of copper) and a corrosion protection structure 110 (e.g., made of aluminum). The material shown can be formed by rolling. A section of the continuous strip can be unrolled and cut from the roll 184 to form a corresponding conductor 126.

[0089] According to Fig. 6, a single strip of the electrical connection structure 117 is juxtaposed and aligned with a single strip of the corrosion protection structure 110.

[0090] According to Fig. 7, however, two strips (with different widths) of the electrical connection structures 117 laterally enclose a parallel extending strip of a corrosion protection structure 110 therebetween.

[0091] Fig. Figure 8 shows a schematic view of a vehicle 160 with a sensor package 100 according to an exemplary embodiment. Consequently, the sensor package 100 can be used for an outdoor application, which may be an automotive application. According to Fig. 8, the package 100 is used as a sensor in an exhaust system 166 of the vehicle 160. The sensor may, for example, be a pressure sensor.

[0092] Thus, the sensor package 100 may form part of an exhaust system 166 and may thus be exposed to a highly corrosive environment during use. The sensor package 100 is electrically coupled to a control block 162, which controls the operation of the vehicle 160, specifically, the operation of an engine 164 thereof.

[0093] Fig. 9 shows a schematic view of an offshore wind turbine 170 with sensor packages 100 according to another exemplary embodiment. In particular, the packages 100 are used here as sensors of an offshore wind turbine 170. The offshore application according to Fig. 9 places the packages 100 in a highly corrosive marine environment (see reference numeral 172). Sensor packages 100 according to exemplary embodiments are mounted on various sections of the wind turbine 170 to detect specific data. Providing the sensor packages 100 with corrosion protection, as described above, can significantly extend the service life of the sensor packages 100 when exposed to corrosive seawater or sea air.

[0094] Fig. 10 shows a cross-sectional view of a lead 126 of a lead frame-like carrier 114 of a package 100 according to an exemplary embodiment.

[0095] According to Fig. 10, the package 100 includes a corrosion protection enhancing structure 150 that 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 enhancing structure 150 may be an anodization coating, a second-stage corrosion protection structure made of a material configured to function as an electron donor for the corrosion protection structure 110, a passivation coating, a phosphating coating, a build-up welding coating, a plasma oxidation coating, and / or a plasma ceramic conversion coating. As shown, the corrosion protection enhancing structure 150 selectively covers only the corrosion protection structure 110, but not the electrical connection structure 117.

[0096] Fig. 10 thus shows an embodiment in which two sections of an electrical connection structure 117 (for example, made of copper) are arranged between a central section of a corrosion protection structure 110 made of aluminum or the like. It can also be seen that exposed surface portions of the corrosion protection structure 110 are in turn covered with the corrosion protection-enhancing structure 150, for example, a zinc or aluminum oxide layer. The corrosion protection-enhancing structure 150 can be selectively applied only to surfaces related to the corrosion protection structure 110.

[0097] Fig. 11 shows a cross-sectional view of a lead 126 of a lead frame-like carrier 114 of a package 100 according to another exemplary embodiment.

[0098] The embodiment of Fig. 11 shows a base or bulk body consisting of an electrical connection structure 117 with a layer of the corrosion protection structure 110 applied only to a partial section of an upper main surface of the layered electrical connection structure 117. Again, the surface of the corrosion protection structure 110 can be selectively covered with the corrosion protection-enhancing structure 150, for example, an aluminum oxide layer, which can be produced as described above. Clearly, the corrosion protection-enhancing structure 150 can enhance the corrosion protection function of the corrosion protection structure 110.

[0099] Fig.12 shows a cross-sectional view of an assembly 130 according to an exemplary embodiment. The assembly 130 comprises a package 100 with the 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, the exposed portion of the electrical connection structure 117 of the package 100 is electrically connected to an electrical contact 134, which is embodied as a plating in a through-hole of the mounting structure 132. Alternatively, the electrical connection structure 117 can also be soldered or sintered onto the mounting structure 132, i.e., can be connected to the mounting structure 132 with a connecting medium, for example, a solder paste or a sinter paste. The corrosion protection structure 110 protects the electrical connection structure 117 against corrosion.

Claims

[1] A package (100) comprising: • a carrier (114); • an electronic component (102) mounted on the carrier (114); and • an encapsulation (106) which encapsulates at least a part of the electronic component (102) and only a part of the carrier (114), so that another exposed part (115) of the carrier (114) is exposed with respect to the encapsulation (106); • wherein the exposed part (115) of the carrier (114) has an electrical connection structure (117) and a corrosion protection structure (110); • wherein the electrical connection structure (117) is selectively formed only on a partial section of the corrosion protection structure (110), or wherein the corrosion protection structure (110) is selectively formed only on a partial section of the electrical connection structure (117), outside the encapsulation (106); and • wherein the carrier (114) has at least one metallic conductor (126) which has the electrical connection structure (117) made of at least one first metal, and which has the corrosion protection structure (110) made of at least one second metal which inhibits corrosion of the at least one first metal; • wherein the corrosion protection structure (110) is strip-shaped; wherein the electrical connection structure (117) and the corrosion protection structure (110) are made of a bimetallic strip which is formed by rolling. [2] The package (100) according to claim 1, wherein the corrosion protection structure (110) comprises or consists of a material configured to function 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 or consists of a material from the group consisting of copper, gold, silver, palladium, iron, nickel and alloys comprising at least one of these materials. [4] The package (100) according to any one of claims 1 to 3, wherein the corrosion protection structure (110) comprises or consists of a material from the group consisting of aluminum, titanium, tantalum, niobium, magnesium, tin, zinc and alloys comprising at least one of these materials. [5] The package (100) according to any one of claims 1 to 4, comprising one of the following features: wherein the electrical connection structure (117) forms a bulk body of the exposed portion (115) of the carrier (114) and the corrosion protection structure (110) is applied to the electrical connection structure (117) with a significantly smaller volume, with no more than 50% of a volume of the electrical connection structure (117); or wherein the corrosion protection structure (110) forms a bulk body of the exposed portion (115) of the carrier (114) and the electrical connection structure (117) is applied to the corrosion protection structure (110) with a significantly smaller volume, with no more than 50% of a volume of the corrosion protection structure (110). [6] The package (100) according to any one of claims 1 to 5, wherein the extension of the corrosion protection structure (110) begins at an edge of the encapsulation (106). [7] The package (100) according to any one of claims 1 to 6, wherein the at least one second metal is arranged between two sections of the at least one first metal in an extension direction of the at least one conductor (126). [8] The package (100) according to any one of claims 1 to 7, comprising the following feature: wherein the at least one first metal and the at least one second metal extend parallel along at least a portion of the at least one conductor (126). [9] The package (100) according to any one of claims 1 to 8, comprising a corrosion protection reinforcing structure (150) which at least partially covers the corrosion protection structure (110) and is configured to reinforce a corrosion protection of the corrosion protection structure (110). [10] The package (100) of claim 9, wherein the corrosion protection reinforcing structure (150) selectively covers the corrosion protection structure (110) but not the electrical connection structure (117). [11] The package (100) according to claim 9 or 10, wherein the corrosion protection enhancing structure (150) comprises at least one of the group consisting of an anodization coating, a second-stage corrosion protection structure comprising or consisting of a material configured to function as an electron donor for the corrosion protection structure (110), a passivation coating, a phosphating coating, a build-up welding coating, a plasma oxidation coating, and a plasma ceramic conversion coating. [12] The package (100) according to any one of claims 1 to 11, wherein the carrier (114) is a lead frame comprising a component mounting section (124) supporting the electronic component (102) and one or a plurality of conductors (126) for electrically coupling the electronic component (102) to an electronic peripheral, wherein the corrosion protection structure (110) is formed as a part of at least one of the one or a plurality of conductors (126). [13] The package (100) according to any one of claims 1 to 12, configured as a sensor package. [14] An arrangement (130), the arrangement (130) comprising: • a mounting structure (132); and • a package (100) according to any one of claims 1 to 13, which is mounted on the mounting structure (132) such that the electrical connection structure (117) is electrically connected to the mounting structure (132). [15] A method of manufacturing a package (100), the method comprising: • Mounting an electronic component (102) on a carrier (114); • encapsulating at least a part of the electronic component (102) and only a part of the carrier (114) by means of an encapsulation (106), so that another exposed part (115) of the carrier (114) is exposed with respect to the encapsulation (106); and • Forming the exposed part (115) of the carrier (114) with an electrical connection structure (117) and with a corrosion protection structure (110), such that the electrical connection structure (117) is selectively formed only on a partial section of the corrosion protection structure (110), or such that the corrosion protection structure (110) is selectively formed only on a partial section of the electrical connection structure (117), outside the encapsulation (106) • wherein the carrier (114) has at least one metallic conductor (126) which has the electrical connection structure (117) made of at least one first metal, and which has the corrosion protection structure (110) made of at least one second metal which inhibits corrosion of the at least one first metal; • wherein the corrosion protection structure (110) is strip-shaped; wherein the electrical connection structure (117) and the corrosion protection structure (110) are made of a bimetallic strip which is formed by rolling. [16] The method of claim 15, wherein the method comprises forming the connected electrical connection structure (117) and the corrosion protection structure (110) by at least one of the group consisting of providing a bimetallic strip, laser welding, and selective plating. [17] The method according to claim 15 or 16, wherein the method comprises forming a corrosion protection reinforcing structure (150) which at least partially covers the corrosion protection structure (110) and is configured to reinforce the corrosion protection of the corrosion protection structure (110). [18] The method of claim 17, wherein the method comprises forming the corrosion protection enhancing structure (150) by at least one of the group consisting of anodizing, forming a second-stage corrosion protection structure from a material configured to function as an electron donor for the corrosion protection structure (110), passivating, phosphating, build-up welding, plasma oxidizing, and performing a plasma-ceramic conversion. [19] A method of using a package (100) according to any one of claims 1 to 13 for outdoor use in a corrosive environment. [20] The method of claim 19, wherein the exterior application is an automotive application. [21] The method of claim 19, wherein the outdoor application is a wind turbine application.

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