Electronic system with intermetallic connection structure and method of manufacturing thereof

Abstract

An electronic system (100) comprises: an at least partially electrically conductive carrier (102); an electronic component (104); and an intermetallic connection structure (106) connecting the carrier (102) and the component (104) and comprising an intermetallic mesh structure (108) in a central portion of the intermetallic connection structure (106) and opposite outer portions (110, 112) without intermetallic mesh and respectively arranged between the intermetallic mesh structure (108) and the carrier 102 or the component (104).

Description

Technical Field

[0001] Various embodiments generally relate to an electronic system and a method of manufacturing the electronic system. Background Technology

[0002] Traditional electronic systems may include electronic components soldered onto a chip carrier such as a lead frame, and may optionally be molded using molding compounds as encapsulation materials. Summary of the Invention

[0003] It may be necessary to connect electronic components to conductive carriers with high reliability in electronic systems.

[0004] According to an exemplary embodiment, an electronic system is provided, comprising at least partially conductive carrier, electronic components, and an intermetallic connection structure connecting the carrier and the components. The intermetallic connection structure includes an intermetallic mesh structure located in a central portion of the intermetallic connection structure and opposing external structures without an intermetallic mesh structure, respectively disposed between the intermetallic mesh structure and the carrier or component.

[0005] According to another exemplary embodiment, a method for manufacturing an electronic system is provided, wherein the method includes: connecting at least partially conductive carrier to electronic components via an intermetallic connection structure; and forming an intermetallic connection structure having an intermetallic mesh structure in a central portion of the intermetallic connection structure and opposite external structures without an intermetallic mesh structure and respectively disposed between the intermetallic mesh structure and the carrier or component.

[0006] According to an exemplary embodiment, a conductive carrier (e.g., a lead frame) and electronic components (e.g., semiconductor dies) are interconnected (particularly by soldering) in an electronic system (e.g., a package or module) via an intermetallic connection structure. Advantageously, the intermetallic connection structure may include a central intermetallic mesh structure in which different metals form a continuous network, and may include peripheral or external structures that do not have a continuous network in the form of an intermetallic mesh. Descriptively, the intermetallic mesh structure can form a high-temperature stable skeleton with high mechanical strength, maintaining the integrity of the solder-type intermetallic connection structure and thus preventing delamination within the electronic system. A first external structure without an intermetallic mesh may be located between the intermetallic mesh structure and the carrier, while a second external structure without an intermetallic mesh may be located between the intermetallic mesh structure and the component. Advantageously, the intermetallic mesh can form a highly reliable mechanical and / or electrical connection between the carrier and the component, thereby being able to withstand high thermal and mechanical loads without the risk of cracking or separation. Undesirable remelting of the intermetallic connection structure can be reliably prevented in the event of a subsequent temperature rise. Advantageously, a top-down connection between components and the carrier can be achieved, which significantly improves the reliability of the resulting electronic system compared to conventional connection structures. Descriptively, the external structure can be a remnant of the metal structure on and between the carrier and components prior to interconnection, and can advantageously smooth the transition between the carrier and components. This avoids abrupt material interfaces between the intermetallic mesh and the carrier and components.

[0007] Description of further exemplary embodiments

[0008] Further exemplary embodiments of the method and electronic system will be explained below.

[0009] In the context of this application, the term "electronic system" may specifically refer to an electronic device comprising one or more electronic components, optionally encapsulated using encapsulation materials. Furthermore, a carrier for the electronic components may be implemented within the electronic system. For example, such an electronic system may be a module or a package.

[0010] In the context of this application, the term "electronic component" specifically includes semiconductor chips (especially power semiconductor chips), active electronics (e.g., transistors), passive electronics (e.g., capacitors or inductors or ohmic resistors), sensors (e.g., microphones, light sensors, or gas sensors), actuators (e.g., loudspeakers), and microelectromechanical systems (MEMS). However, in other embodiments, electronic components may also be of different types, such as electromechanical components, especially mechanical switches, etc.

[0011] In the context of this application, the term "intermetallic connection structure" may specifically refer to a medium that reliably connects components and a carrier and includes a variety of different metallic compositions.

[0012] In the context of this application, the term "intermetallic network structure" can specifically refer to a network of metallic structures composed of different metallic materials within a metallic matrix, which forms a continuous connection between opposing metallic external structures (which do not have such a network). Intermetallic network structures can include fibers or filaments, which can consist of interconnected metallic particles of different metallic materials. For example, such fibers or filaments can be fused together or interconnected.

[0013] In the context of this application, the term "external structure without intermetallic mesh" can specifically refer to a metal structure that connects an intermetallic mesh structure to electronic components or conductive carriers but does not form a continuous network of different metals. The external structure can be an intermetallic structure, but without forming a continuous network of different metal components establishing uninterrupted vertical connections. The external structure can also include different metallic materials, but these metallic materials do not form continuous vertical connections in the form of a mesh or network. In contrast, the external structure can include a matrix metal in which individual metal islands and / or short intermetallic segments can be embedded without forming continuous vertical connections through the matrix metal. An external structure without intermetallic mesh can also provide mechanical and / or conductive connections without a continuous vertical intermetallic network, and can be manufactured, for example, according to [specific manufacturing process]. Figures 1 to 8 The residue left over from the manufacturing process.

[0014] In one embodiment, the carrier includes a lead frame structure (e.g., made of copper). Therefore, the carrier can be implemented as a patterned metal sheet, thus allowing for simple and easy fabrication.

[0015] However, the carrier can be alternatively implemented in another manner, for example, as comprising a central electrically insulating thermally conductive sheet (e.g., made of ceramic) and a conductive layer (e.g., a copper or aluminum layer) covering one or both opposite main surfaces of the central electrically insulating thermally conductive sheet. For example, the carrier can be implemented as a DAB (Direct Aluminum Bond) substrate, DCB (Direct Copper Bond) substrate, etc. Furthermore, the carrier can also be configured as an Active Metal Brazing (AMB) substrate.

[0016] In one embodiment, the carrier comprises a conductive body (e.g., made of copper or aluminum) partially covered by a metal diffusion barrier layer. For example, a surface of the body or a portion thereof may be covered with a metal diffusion layer made of nickel. This can inhibit excessive diffusion of material from the body into the intermetallic connection structure.

[0017] In one embodiment, the component includes a semiconductor body covered with a back metallization, the back metallization being connected to an intermetallic interconnect structure. For example, the semiconductor body may be made of silicon. At least one monolithic integrated circuit element may be formed in the semiconductor body, such as a transistor structure and / or a diode structure. For example, the active surface of the semiconductor body in which at least one integrated circuit element is monolithically integrated may be opposite to another surface of the semiconductor body to which the back metallization is applied.

[0018] In one embodiment, the intermetallic connection structure includes a solder matrix for creating a solder bond between the component and the carrier. For example, the solder matrix may be made of a solderable material (preferably tin) having a melting temperature lower than that of each of the other metallic elements in the intermetallic network structure. During the reflow process, only the material of the solder matrix is ​​selectively meltable or becomes liquid or flowable, while the different metallic materials of the intermetallic network structure that may form during such a reflow process may remain as solid particles and thus may dissolve in the flowable solder matrix. This provides a good basis for forming an intermetallic network structure with a high melting point within a solder matrix with a lower melting point, thereby reliably protecting the intermetallic connection structure after its formation from unwanted remelting.

[0019] In one embodiment, the solder matrix comprises tin. Other solderable materials are also possible.

[0020] In one embodiment, the intermetallic connection structure includes intermetallic phase promoter particles (which may be macroscopic or microscopic particles, or even atomic-level particles) composed of at least one intermetallic phase promoter metal, for promoting the formation of intermetallic phases within the intermetallic connection structure. These intermetallic phase promoter particles can promote the formation of intermetallic network structures and can be included in solder paste applied between the carrier and electronic components during electronic system manufacturing. For example, the at least one intermetallic phase promoter metal includes silver and / or copper. Such materials can have a higher melting point than the solder matrix (e.g., tin) of the intermetallic connection structure and are capable of forming intermetallic phases with other metals in a flowable solder medium.

[0021] In one embodiment, the intermetallic connection structure includes intermetallic phase accelerating particles composed of at least one intermetallic phase accelerating metal for accelerating the formation of an intermetallic network structure. The intermetallic phase accelerating particles may be provided by a dedicated layer disposed on top of a carrier, and / or may be provided in the form of particles embedded in the solder matrix of solder paste applied between the carrier and components during electronic system manufacturing. This intermetallic phase accelerating material can accelerate, trigger, or even catalyze the formation of the intermetallic network structure in a temporary flowable solder matrix and can facilitate the formation of an intermetallic layer that bonds the chip and carrier surfaces together. For example, the at least one intermetallic phase accelerating metal may include palladium, gold, platinum, and / or zinc. However, the intermetallic phase accelerating metal may also be a metal from the back side of the wafer (i.e., the back metallization of the electronic component), such as vanadium.

[0022] In one embodiment, the intermetallic connection structure is lead-free (Pb). This is highly advantageous as it prevents the biohazardous properties of the intermetallic connection structure. Therefore, environmentally friendly electronic systems can be formed by avoiding lead in the intermetallic connection structure.

[0023] In one embodiment, the vertical thickness of the intermetallic connection structure is in the range of 5 μm to 50 μm, particularly in the range of 10 μm to 30 μm, and even more particularly in the range of 10 μm to 20 μm. Advantageously, the described intermetallic connection structure or bonding wire can have a very low thickness. This allows the electronic system to remain compact in the vertical direction and ensures high mechanical, thermal, and electrical reliability of the electronic system.

[0024] In one embodiment, the electronic system includes at least one intermetallic phase accelerating layer made of an intermetallic phase accelerating metal, which is used to accelerate the formation of an intermetallic network structure and is disposed between a carrier and an intermetallic connection structure. During manufacturing, the intermetallic phase accelerating layer can serve as a reservoir for intermetallic phase accelerating particles dissolved in a temporarily flowable solder matrix. Together with intermetallic phase promoter particles in the solder matrix, the intermetallic phase accelerating particles are components of the high-melting-point intermetallic network structure formed in the lower-melting-point solder matrix of the intermetallic connection structure.

[0025] In one embodiment, the intermetallic phase acceleration layer is a single layer (see, for example, [link to previous embodiment]). Figure 2 ) or double-layered (see, for example, see Figure 3 Single layers can be easily formed, while double layers allow for fine-tuning of the properties of the intermetallic phase acceleration layer.

[0026] In one embodiment, a portion of the vertical thickness of the intermetallic mesh structure is at least 80%, particularly at least 90%, relative to the entire intermetallic phase structure. Therefore, a significant portion of the vertical thickness of the intermetallic phase structure may be contributed by the intermetallic mesh structure. Consequently, the reinforcing and anti-remelting functions of the intermetallic mesh or network can be provided over a significant sub-range of the entire intermetallic connection structure.

[0027] In one embodiment, the intermetallic mesh structure is formed as a branched network of interconnected multimetallic particles extending continuously across the entire vertical spacing between the outer structures. Therefore, the intermetallic mesh structure can be composed of multiple interconnected filaments or fibers, each filament or fiber being formed from a sequence of directly connected metal particles of at least two different metallic chemical elements, preferably at least three, such as three, four, or five different metallic chemical elements. The various intermetallic filaments of the fibers in the intermetallic mesh structure may include one or more fusion and / or intersection points and can cover the entire vertical range between two opposite outer structures of the intermetallic connection structure.

[0028] In one embodiment, the intermetallic mesh structure accounts for a weight percentage of 1% to 30% of the total intermetallic connection structure, particularly 3% to 8%, and more particularly 4.5% to 6.5%. Preferably, the intermetallic mesh structure contributes a relatively small portion of the weight. This ensures proper fluidity of the intermetallic connection structure during reflow soldering (due to the solder matrix) while preventing remelting after the soldering process is complete. The relatively smooth properties of the solder matrix, which may have the highest material contribution in the intermetallic connection structure, can also serve as a mechanical buffer in electronic systems.

[0029] In one embodiment, the method includes forming an intermetallic connection structure by applying solder paste to a carrier, the solder paste comprising a solder matrix for creating a solder bond between a component and the carrier, and intermetallic phase accelerator particles composed of at least one intermetallic phase accelerator metal for promoting the formation of intermetallic phases within the intermetallic connection structure. Optionally, the intermetallic phase accelerator particles may also be added to the solder matrix. Additionally or alternatively, the intermetallic phase accelerating material may be provided as a coating on the carrier below the solder paste. Therefore, the method may include: covering the carrier with an intermetallic phase accelerating layer to accelerate the formation of an intermetallic network structure; and disposing the intermetallic phase accelerating layer between the carrier and the solder paste. Additionally or alternatively, the method may include providing intermetallic phase accelerating particles to the solder paste to accelerate the formation of the intermetallic network structure.

[0030] In one embodiment, the method includes providing intermetallic particles to the solder paste, the intermetallic particles having a diameter in the range of 5 μm to 50 μm, particularly in the range of 10 μm to 20 μm. This results in a thinner joint line formed during the soldering process.

[0031] In one embodiment, the method includes extruding solder paste between a carrier and a component. Advantageously, this extrusion process can apply sufficient mechanical pressure to the solder paste to form a single layer of intermetallic particles of the solder paste between the carrier and the component. In other words, after this extrusion process, only a single solder paste particle bridges the carrier and the component. This ensures a small weld line or thickness in the manufactured intermetallic connection structure.

[0032] In one embodiment, the method comprises forming an intermetallic connection structure by heating a precursor of the intermetallic connection structure (particularly solder paste, comprising a solder matrix and intermetallic phase promoter particles and optionally intermetallic phase accelerating particles, or one or more intermetallic phase accelerating layers beneath the solder paste) to a peak temperature above the melting temperature of the solder precursor (i.e., the solder matrix) but below the melting temperature of the intermetallic network precursor (i.e., the intermetallic phase promoter and accelerating particles and / or layers). Through this heating process, the solder matrix becomes flowable, while the intermetallic phase promoter and accelerating particles and / or layers remain solid and can dissolve in the flowable solder matrix. The formation of this mixture, combined with appropriate temperature characteristics, triggers the formation of an intermetallic network structure within the solder matrix. After the solder matrix re-solders, the intermetallic connection structure as a whole is reliably protected against unwanted remelting, as this is inhibited by the intermetallic network structure.

[0033] In one embodiment, the method includes maintaining the peak temperature for a period of at least one minute, particularly in the range of one to four minutes, and more particularly in the range of 1.5 to 2 minutes. Advantageously, the mixture can be maintained in a partially flowable phase for a relatively long period. This allows sufficient time for the mixture to form an intermetallic mesh structure that extends along the entire vertical spacing between two opposite outer structures without an intermetallic mesh.

[0034] In one embodiment, the peak temperature is in the range of 260°C to 350°C, particularly in the range of 280°C to 300°C. In comparison, the melting temperature of the solder precursor may be below 240°C. Furthermore, the melting temperature of the intermetallic network precursor can be at least 370°C. As a result of this treatment, the solder matrix selectively becomes flowable, while the metal particles forming the intermetallic network structure do not melt during soldering.

[0035] In one embodiment, the method includes forming an intermetallic connection structure through reflow soldering. Reflow soldering can refer to the process of temporarily attaching one or more electronic components to a carrier using solder paste (particularly a viscous mixture of solderable particles and flux, additionally rich in precursors for forming an intermetallic mesh structure), after which the entire assembly is subjected to controlled heat. The solder paste, but not the precursors for forming the intermetallic mesh structure, is reflowed in a molten state to form a permanent solder joint. For example, heating can be accomplished by passing the assembly through a reflow oven, such as under an infrared lamp.

[0036] In one embodiment, the mesh structure and the outer structure comprise the same intermetallic material. Although the concentrations of various intermetallic materials may differ in the mesh structure and the two opposite outer structures, the sources of the various metals in the mesh structure and the outer structures may be the same due to the described manufacturing process. For example, the lower outer structure may include one or more metallic materials of an intermetallic phase acceleration layer sandwiched between the carrier and the solder matrix, as well as particles of the solder matrix. Similarly, the upper outer structure may include metallic materials of a back metallization sandwiched between the semiconductor body of the electronic component and the solder matrix, as well as particles of the solder matrix. The intermetallic mesh structure may include particles of the solder matrix, one or more metallic materials of an intermetallic phase acceleration layer sandwiched between the carrier and the solder matrix, one or more metallic materials of intermetallic phase promoter particles, and particles of a back metallization layer sandwiched between the semiconductor body of the electronic component and the solder matrix.

[0037] In one embodiment, the electronic system includes an encapsulating material that at least partially encapsulates at least one of at least one electronic component, a carrier, and an intermetallic connection structure. In the context of this application, the term "encapsulating material" may specifically refer to a substantially electrically insulating and preferably thermally conductive material that surrounds at least a portion of the component, at least a portion of the carrier, and a portion of the intermetallic connection structure. For example, the encapsulating material may be a molding compound and may be produced, for example, by transfer molding. Alternatively, the encapsulating material may be a casting compound formed by casting.

[0038] In one embodiment, at least one of the at least one electronic component is a bare die. The compactness of the electronic system can be further improved by implementing at least one electronic component as an unencapsulated chip, i.e., a pure semiconductor chip without additional dielectric encapsulation material.

[0039] In one embodiment, the electronic system includes multiple (particularly electronic) components mounted on the same or different carriers. Therefore, the electronic system may include one or more electronic components (e.g., at least one passive element, such as a capacitor, and at least one active element, such as a semiconductor chip).

[0040] In one embodiment, the electronic device includes a mounting base (e.g., a printed circuit board, PCB), a carrier, and an electronic component mounted on the mounting base, and the mounting base is electrically coupled to the electronic component and / or the carrier. Such a mounting base may be an electronic board serving as a mechanical base for an electronic system, for example, implemented as a package.

[0041] In one embodiment, the electronic system is configured as one of the following groups: a power module connected by a leadframe, a transistor outline (TO) electronic system, a quad flat leadless (QFN) electronic system, a small outline (SO) electronic system, a small outline transistor (SOT) electronic system, and a thin small outline (TSOP) electronic system. Electronic systems for sensors and / or electromechanical devices are also possible embodiments. Furthermore, exemplary embodiments may also relate to electronic systems used as nanobatteries or nanofuel cells, or other devices having chemical, mechanical, optical, and / or magnetic actuators. Therefore, the electronic system according to one exemplary embodiment is fully compatible with standard packaging concepts (particularly with standard TO packaging concepts).

[0042] In one embodiment, the electronic system is configured as a power module, such as a molded power module. For example, an exemplary embodiment of the electronic system may be an intelligent power module (IPM). Another exemplary embodiment of the electronic system is a dual in-line package (DIP) electronic system.

[0043] In one embodiment, the electronic component is configured as a power semiconductor chip. Therefore, the electronic component (e.g., the semiconductor chip) can be used in power applications, such as in the automotive field, and may have, for example, at least one integrated insulated-gate bipolar transistor (IGBT) and / or at least one other type of transistor (e.g., MOSFET, JFET, etc.) and / or at least one integrated diode. Such integrated circuit elements can be manufactured, for example, using silicon technology or based on wide-bandgap semiconductors (e.g., silicon carbide). The semiconductor power chip may include one or more field-effect transistors, diodes, inverter circuits, half-bridges, full-bridges, drivers, logic circuits, other devices, etc.

[0044] As the substrate or wafer on which the electronic components are formed, a semiconductor substrate, particularly a silicon substrate, can be used. Alternatively, silicon oxide or another insulating substrate can be provided. Germanium substrates or III-V semiconductor materials can also be implemented. For example, exemplary embodiments can be implemented using GaN or SiC technology.

[0045] Furthermore, exemplary embodiments may utilize standard semiconductor processing techniques, such as appropriate etching techniques (including isotropic and anisotropic etching techniques, particularly plasma etching, dry etching, and wet etching), patterning techniques (which may involve photolithographic masks), and deposition techniques (e.g., chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), sputtering, etc.).

[0046] The above and other objects, features and advantages will become apparent from the accompanying drawings, the following description and the appended claims, in which like parts or elements are indicated by like reference numerals. Attached Figure Description

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

[0048] In the attached diagram:

[0049] Figure 1 A schematic cross-sectional view of an electronic system according to an exemplary embodiment and a cross-sectional view of an electronic system manufactured according to an exemplary embodiment are shown.

[0050] Figures 2 to 8 It is according to an exemplary embodiment in manufacturing such as Figure 1 A cross-sectional view of the structure obtained during the electronic system shown.

[0051] Figure 9 A cross-sectional view of an electronic system according to another exemplary embodiment is shown.

[0052] Figure 10 A cross-sectional view of an electronic system according to yet another exemplary embodiment is shown.

[0053] Figures 11 to 13 This is a cross-sectional view of a structure obtained during the manufacture of an electronic system according to yet another exemplary embodiment.

[0054] Figure 14 This is a phase diagram illustrating the properties of different intermetallic phases produced by mixing silver, gold, and tin, used to explain the principles of an exemplary embodiment.

[0055] Figure 15 This is a graph illustrating a reflow soldering process performed during the manufacture of an electronic system according to an exemplary embodiment.

[0056] Figure 16 and Figure 17 A method for manufacturing an electronic system according to an exemplary embodiment is shown.

[0057] Figure 18A cross-sectional view of an electronic system according to yet another exemplary embodiment is shown. Detailed Implementation

[0058] The illustrations in the image are schematic and not necessarily to scale.

[0059] Before describing the exemplary embodiments in more detail with reference to the accompanying drawings, some general considerations will be summarized based on the exemplary embodiments that have been developed.

[0060] According to exemplary embodiments, an electronic system can be provided having a bonding material in the form of an intermetallic connection structure between an electronic component (e.g., a bare die with a back metallization) and a conductive carrier (e.g., a lead frame), exhibiting excellent connection characteristics. The intermetallic connection structure may be formed with an intermetallic mesh in the middle (preferably embedded in a matrix of solder material with a melting point lower than the intermetallic mesh) and layers without the mesh formed at the top and bottom (i.e., respectively facing the component and the carrier). This allows for a reliable connection between the component and the carrier, and a non-remelting reinforced solder structure that remains stable even at high temperatures. Since the aforementioned intermetallic connection structure can be formed without lead (Pb) material, interconnection can be achieved without biohazards and pollution issues.

[0061] Therefore, an exemplary embodiment provides a non-remelting lead-free solder structure in the form of an intermetallic connection structure. Thus, an exemplary embodiment provides a method for producing a common low-melting-point lead-free solder with advantageous non-remelting properties due to the formation of an intermetallic network. More specifically, an exemplary embodiment provides a general lead-free solder structure having a vertically fused intermetallic compound network that can withstand even very high reflow temperatures without remelting. This characteristic can be considered to be achieved and facilitated particularly by the extension of the intermetallic network across the bond line. Advantageously, even in the case of partial or localized remelting, this solder bond line can remain intact during reflow. This intermetallic connection structure can be formed using a dopant, which can be provided by plating on a carrier in the solder system. Advantageously, fine solder balls can be used to reduce the bond line after die bonding, thereby enhancing the formation of the vertical intermetallic network. Therefore, a lead-free solder alternative can be obtained without undesirable remelting characteristics.

[0062] Therefore, a key aspect of an exemplary embodiment is to provide a connection system capable of using a universal low-melting-point lead-free solder that does not remelt after reflow due to the formation of an intermetallic compound network. Thus, the intermetallic compound network can be formed in the intermetallic connection structure spanning the bond line, which can withstand reflow temperatures without remelting, thereby improving the reliability of the resulting electronic system. In particular, the corresponding intermetallic connection structure is capable of maintaining the integrity of the solder bond line during reflow, even in the event of partial or spatial localized remelting.

[0063] To fabricate this intermetallic connection structure, a fine solder paste for low-bond lines can be provided prior to the reflow process. Thus, such low-bond lines can be created prior to the reflow process, where the bond thickness does not exceed 40 μm (e.g., Type 5 solder paste, where the nominal solder ball size can be in the range of 20 μm to 25 μm, can be used for this purpose).

[0064] In addition, one or more dopants may be provided in the form of one or more carrier coatings: such dopant systems may include (i) one or more elements that have high solubility (especially high dispersibility) in solder (e.g., gold (Au), palladium (Pd) etc.) which help to form a uniform intermetallic compound network across the bonding line, and (ii) one or more elements (e.g., zinc (Zn), nickel (Ni) etc.) that enhance the reliability of solder joints.

[0065] Regarding the reflow characteristic curve applied during the manufacture of an electronic system according to an exemplary embodiment, the maximum peak temperature can be approximately the glass transition temperature (Tg) of the organic carrier (which is typically in the range of 260°C to 350°C to manage warpage), and the liquidus duration (possibly in the range of 1 to 2 minutes) is sufficient to form an intermetallic compound network. This allows the formation of vertically bonded intermetallic compound networks with different metals, which can also be referred to as an intermetallic network structure in an intermetallic connection structure. Corresponding external structures without intermetallic networks can be formed at the upper and lower peripheries of the intermetallic connection structure.

[0066] More specifically, the intermetallic network structure (or network intermetallic compound) can be a complex mixture of different intermetallic compound species, such as: (i) Ag3Sn; (ii) Cu3Sn; and / or (iii) Pd and Au intermetallic network compound species in the lower ppm range.

[0067] When such an intermetallic network is formed, the copper content in the bulk solder may become very low. This could indicate a pulling element that facilitates the formation of the intermetallic network.

[0068] In one embodiment, the host solder, which can also form the matrix of the intermetallic connection structure, may be primarily tin (Sn). Simultaneously, the Sn content in both the intermetallic compound and the host solder may be high. This could indicate that Sn is trapped to form the intermetallic compound, potentially leaving a lower content of free Sn, which is a common cause of remelting throughout the solder joint.

[0069] According to one exemplary embodiment, additional metal dopants (e.g., nickel and / or palladium) can contribute to the formation of an intermetallic compound network. Printing or dispensing a thin layer of solder may be sufficient to cover the bare die area.

[0070] Advantageously, the bonding line thickness before the reflow process can be in the range of 25 μm to 50 μm, and after the reflow process, it can be in the range of 10 μm to 30 μm.

[0071] Figure 1 A schematic cross-sectional view of an electronic system 100 according to an exemplary embodiment and a cross-sectional view of an electronic system 100 manufactured according to an exemplary embodiment are shown. Figure 1 On the left side, an experimentally manufactured electronic system 100 is shown, while Figure 1 A schematic diagram of this electronic system 100 is shown on the right. The electronic system 100 can be configured as a semiconductor package or module.

[0072] On its underside, the electronic system 100 may include a conductive carrier 102, such as a lead frame (e.g., a patterned copper plate). More specifically, the carrier 102 includes a conductive body 114, which may be made of, for example, copper, and may be covered by a metal diffusion barrier layer 116, such as a layer made of nickel. Descriptively speaking, the metal diffusion barrier layer 116 inhibits or even eliminates the diffusion of metallic material from the body 114 into the intermetallic phase accelerating layer 128.

[0073] Furthermore, the electronic component 104, which can be implemented as a semiconductor die, can form the upper part of the electronic system 100. In the illustrated embodiment, component 104 includes a semiconductor body 118 (e.g., made of silicon and having at least one monolithic integrated circuit element, not shown). The semiconductor body 118 is covered with a back metallization 120, for example, a layer made of copper, which is connected to the intermetallic interconnect structure 106.

[0074] For example Figure 1As shown, the conductive solder-type intermetallic connection structure 106 is arranged vertically between the carrier 102 and the component 104 for mechanical and electrical interconnection of the carrier 102 and the component 104. The intermetallic connection structure 106 includes an intermetallic mesh structure 108 located in the central portion of the intermetallic connection structure 106. The intermetallic mesh structure 108 can be considered as a network of different metal particles embedded in a metal matrix of another metal material, forming continuous conductive paths in the vertical direction. Furthermore, as... Figure 1 As shown, the lower outer structure 110 is vertically arranged between the carrier 102 and the intermetallic mesh structure 108. Furthermore, the upper outer structure 112 is vertically arranged between the intermetallic mesh structure 108 and the component 104. More specifically, the upper outer structure 112 is directly arranged between the bottom intermetallic mesh structure 108 and the top pure back metallization portion 120 (made of homogeneous material). As a result of the manufacturing process described below, the mesh structure 108 and the outer structures 110, 112 comprise the same intermetallic material (tin, palladium, gold, silver, nickel, and copper in the illustrated embodiment), but have different concentrations along the vertical thickness of the intermetallic connection structure 106.

[0075] Advantageously, the intermetallic connection structure 106 includes a solder matrix 122, which may be provided based on tin, for forming a solder connection between the component 104 and the carrier 102. The solder matrix 122 may have a relatively low melting temperature. Furthermore, the intermetallic connection structure 106 includes intermetallic phase promoter particles 124 composed of one or more intermetallic phase promoter metals, configured to promote the formation of intermetallic phases within the intermetallic connection structure 106. For example, silver and / or copper may be used as intermetallic phase promoter metals. Descriptively, the intermetallic phase promoter particles 124 may be included in the solder paste used as the basis for manufacturing the intermetallic connection structure 106 (see [link to solder paste]). Figure 4 As shown in the attached figure (reference numeral 130), it can contribute to the formation of the intermetallic network together with the particles of the underlying intermetallic phase acceleration layer 128.

[0076] Similarly, Figure 1As shown, the intermetallic connection structure 106 may include intermetallic phase accelerating particles 126 composed of one or more intermetallic phase accelerating metals for accelerating the formation of the intermetallic network structure 108. The one or more intermetallic phase accelerating metals may include palladium, gold, platinum, and / or zinc. As a source of the intermetallic phase accelerating particles 126, the electronic system 100 includes an intermetallic phase accelerating layer 128 (composed of at least one of the aforementioned intermetallic phase accelerating metals) for accelerating the formation of the intermetallic network structure 108 and is disposed between the carrier 102 and the intermetallic connection structure 106. As shown, the intermetallic phase accelerating layer 128 may be a single layer of homogeneous material immediately below the lower outer structure 110. The intermetallic phase accelerating layer 128 may also be represented as a dopant layer or protective layer, and may include one or more materials (e.g., palladium, gold, zinc, etc.) having a higher melting point than the material of the solder matrix 122 (especially tin) and acting as a seed or promoter to form the vertically connected intermetallic network structure 108. The high melting point of the material of the intermetallic phase acceleration layer 128 advantageously suppresses the remelting of the intermetallic network structure 108 after its formation, even at high reflow temperatures.

[0077] Advantageously, the intermetallic connection structure 106 can be lead-free. This makes the material of the intermetallic connection structure 106 biocompatible and avoids any highly undesirable biohazard properties of the electronic system 100.

[0078] Still referencing Figure 1 The vertical thickness D of the intermetallic connection structure 106 can preferably be in the range of 10 μm to 20 μm, for example, it can be 15 μm. Furthermore, a portion of the vertical thickness of the intermetallic mesh structure 108 divided by the total vertical thickness D of the intermetallic connection structure 106 can be, for example, at least 80%, preferably at least 90%. For example, the portion of the vertical thickness can be in the range of 8 μm to 16 μm, for example, it can be 12 μm.

[0079] like Figure 1As shown, the intermetallic mesh structure 108 is formed as a branched network of interconnected multimetallic particles extending continuously across the entire vertical spacing between the outer structures 110 and 112. Although the intermetallic mesh structure 108 does not extend perfectly straight between the outer structures 110 and 112, it provides an uninterrupted, continuous conductive intermetallic connection between the outer structures 110 and 112. The intermetallic mesh structure 108 is embedded in the solder matrix 122 and can be made of a variety of different metals, particularly at least three different metals. The intermetallic mesh structure 108 can be formed by directly connecting metal particles of different chemical elements. Advantageously, the presence of the intermetallic mesh structure 108 in the solder matrix 122 prevents undesirable remelting of the entire intermetallic connection structure 106, despite the relatively low melting temperature of the tin material in the solder matrix 122. Advantageously, this can be achieved by a relatively low weight percentage of the weight of the intermetallic mesh structure 108 relative to the weight of the entire intermetallic connection structure 106. For example, the weight percentage can be in the range of 4.5% to 6.5%.

[0080] Advantageously, due to the provision of the solder matrix 122, the described intermetallic connection structure provides a reliable mechanical and electrical connection between the suitably solderable carrier 102 and component 104, while reliably preventing remelting (especially at typical reflow temperatures) due to the formation of the intermetallic mesh structure 108. Synergistically, the opposing external structures 110, 112 ensure a smooth material transition between the intermetallic mesh structure 108 embedded in the solder matrix 122, the intermetallic phase acceleration layer 128, and the back metallization portion 120. The intermetallic connection structure 106 exhibits high mechanical and thermal stability, thus resulting in a more reliable electronic system 100. Given its material composition, it neither harms the user nor poses a risk of remelting during reflow. Therefore, the electronic system 100 provides high thermal, mechanical, and electrical performance.

[0081] Figures 2 to 8 According to an exemplary embodiment, in manufacturing such as Figure 1 A cross-sectional view of the structure obtained during the process of the electronic system 100 shown.

[0082] refer to Figure 2The carrier 102 is shown covered with an intermetallic phase accelerating layer 128 for later accelerating the formation of the intermetallic network structure 108. As described above, the carrier 102 can be formed from a copper substrate or body 114 covered with a metal diffusion barrier layer 116 made of nickel. The metal diffusion barrier layer 116 can prevent the material of the body 114 from diffusing in the upward direction. The intermetallic phase accelerating layer 128 can be a plated dopant layer, which can be made of palladium and gold. For example, the thickness b of the intermetallic phase accelerating layer 128 can be in the range of 0.05 μm to 1 μm, for example 0.1 μm. Therefore, according to Figure 2 The intermetallic phase accelerating layer 128 is a single layer. More generally, possible plating dopants used to form the intermetallic phase accelerating layer 128 are palladium, gold, platinum, and zinc.

[0083] refer to Figure 3 This shows the alternative Figure 2 The layer sequence of the layer sequence. According to Figure 3 The carrier 102 is covered with a two-layer intermetallic phase acceleration layer 128. In the example shown, the bottom layer 128A (also referred to as the dopant layer) formed on the carrier 102 comprises zinc, while the top layer 128B (also referred to as the combined dopant and protective layer) formed on the bottom layer 128A may, for example, comprise palladium and gold.

[0084] As already mentioned, Figure 2 and Figure 3 Two examples of a carrier 102 having a doped coating in the form of an intermetallic phase accelerating layer 128 are shown. This intermetallic phase accelerating layer 128 can be constructed as a single layer or multiple layers. The following process will be based on... Figure 2 The structure shown will be explained, where it can be based on Figure 3 The structure shown will be used to perform the corresponding process.

[0085] refer to Figure 4 Solder paste 130 can be applied to a carrier 102 covered with an intermetallic phase accelerating layer 128. As shown, the solder paste 130 includes intermetallic particles 132, which include a solder matrix 122 (preferably made of tin) for forming a solder connection between the component 104 and the carrier 102. Furthermore, the intermetallic particles 132 include intermetallic phase promoter particles 124 within the solder matrix 122. The intermetallic phase promoter particles 124 can be made of one or more intermetallic phase promoter metals to promote the formation of intermetallic phases within the intermetallic connection structure 106. In the illustrated embodiment, the intermetallic phase promoter particles 124 include a first type of particle and a second type of particle. For example, the first type of particle can be made of silver, while the second type of particle can be made of copper.

[0086] Therefore, after the carrier 102 is coated with an intermetallic phase acceleration layer 128 to accelerate the formation of the intermetallic mesh structure 108, the intermetallic phase acceleration layer 128 can be covered with solder paste 130.

[0087] Despite Figures 2 to 8 Not shown, but added to or replacing the planar intermetallic phase accelerating layer 128, intermetallic phase accelerating particles 126 can be provided in the solder paste 130 (see...). Figure 1 This accelerates the formation of the intermetallic network structure 108. This avoids the need to deposit a dedicated intermetallic phase acceleration layer 128 on the carrier 102.

[0088] It should be understood that the solder printing process shown is not limited to a specific solder type, but depends on the requirements of the final solder joint. Therefore, many different solder systems can be implemented in different embodiments. For example, a suitable solder paste 130 may primarily contain Sn and small amounts of one or more other metallic elements. For instance, 3% by weight of silver and 0.5% by weight of Cu can be added to the Sn matrix in solder paste 130 used in an exemplary embodiment. Solder paste 130 may also contain flux, additives, etc.

[0089] refer to Figure 5 An electronic component 104, consisting of a semiconductor body 118 and a back metallization portion 120, can be pressed from the top side onto the applied solder paste 130. Thus, the solder paste 130 is pressed between the carrier 102 and the component 104, forming a layer of substantially uniform thickness. Advantageously, the intermetallic particles 132 of the solder paste 130 can be planarized by mechanical pressure applied between the carrier 102 and the component 104, thereby forming a monolayer 134 of solderable intermetallic particles 132 (optionally in a solvent matrix, not shown). The diameter d of the intermetallic particles 132 of the solder paste 130 is preferably in the range of 10 μm to 20 μm, for example, 15 μm. During die bonding, the solder layer can thus be pressed down to the monolayer 134, which allows for control over the definition of the bond line thickness. The bond line thickness describes the thickness of the solderable material between the carrier 102 and the component 104. During the described process, additional dopants, such as Cu, Au, Pd, and / or V, can be provided from the back side of the die.

[0090] refer to Figure 6The process of interconnecting the conductive carrier 102 with the electronic component 104 via the intermetallic connection structure 106 begins. More specifically, the formation of the intermetallic connection structure 106 is triggered by heating the precursor of the intermetallic connection structure 106 to a peak temperature higher than the melting temperature of the solder matrix 122, which serves as the solder precursor, but lower than the melting temperature of the intermetallic mesh precursor and the material of layers 128 and / or 120. The intermetallic mesh precursor can here be implemented as intermetallic phase promoter particles 124. Descriptively speaking, Figure 5 The structure is heated to melt the solder matrix 122 without melting the materials marked with reference numerals 120, 124, and / or 128. Advantageously, during this selective melting process, the highest or peak temperature, preferably in the range of 280°C to 300°C, can be maintained for a period of preferably 1.5 to 2 minutes. For example, the melting temperature of the solder precursor in the form of solder matrix 122 is below 240°C (e.g., the melting point of tin can be approximately 230°C). In contrast, the melting temperature of the aforementioned intermetallic mesh precursor can be significantly higher than 300°C.

[0091] Specifically, the described process can form the intermetallic connection structure 106 by reflow soldering. During the reflow soldering, the material of the solder matrix 122 reaches and exceeds its melting point and becomes liquid, while the composition of the formed intermetallic mesh structure 108 can remain solid.

[0092] refer to Figure 7 When the material of the solder matrix 122 becomes liquid, the dopant becomes a solute (descriptively, the elemental concentration difference drives the diffusion process) and dissolves into the liquid bulk solder. In addition to the intermetallic phase promoter particles 124, the intermetallic phase accelerating particles 126 can be separated from the intermetallic phase accelerating layer 128. Furthermore, additional particles can be separated from the back metallization portion 120 and can dissolve into the liquid solder matrix 122.

[0093] refer to Figure 8 The formation of the intermetallic connection structure 106 continues by dissolving additional particles in the liquid solder matrix 122. In this way, a result can be obtained according to... Figure 1The intermetallic connection structure 106 may include an intermetallic mesh structure 108 in the central portion and opposite external structures 110, 112 without the intermetallic mesh, wherein the external structures 110, 112 are respectively arranged between the intermetallic mesh structure 108 and the carrier 102 or component 104. Due to the described manufacturing method, the mesh structure 108 and the external structures 110, 112 include the same intermetallic material, i.e., tin, copper, gold, silver, palladium, zinc, etc., specifically depending on the material used for the solder paste 130, the intermetallic phase acceleration layer 128, and the back metallization portion 120. Certain components of the material of the carrier 102 may also be included in the intermetallic connection structure 106.

[0094] For the described manufacturing process, a dopant system combining paste and plating can be used. Since solder paste 130 can be printed onto the plating surface and a reflow process can be performed, the plating elements on carrier 102 can be dopants, such as Pd and Au. Besides the freedom to choose different materials for solder paste 130 (e.g., SAC305, SAC405, or Ni-doped paste), other elements, such as Zn, are also possible for different mission profiles or reliability requirements. Advantageously, the dopants from carrier 102 do not affect the usability of solder paste 130 (e.g., flowability, wettability, melting point, etc.). The relevant elements may continue to diffuse, resulting in a more homogeneous solution of the bulk solder. The dispersed dopants can be used as seeds for generating intermetallic compound networks or intermetallic network structures 108.

[0095] Refer again Figures 1 to 8 In one embodiment, when reaction energy is provided (during the peak temperature and hold time of the reflow process), the dopant (particularly from the structures shown by reference numerals 124, 128) begins to form intermetallic compounds with Sn from the solder matrix 122, thereby producing an intermetallic network structure 108. Similarly, strong connections 110, 112 can be generated in the form of external structures along the carrier 102 and component 104 (particularly at the chip back contact interface according to reference numeral 120).

[0096] Advantageously, the intermetallic network structure 108 or the intermetallic compound network does not remelt during normal reflow processes (e.g., peak temperatures of about 260°C). Descriptively speaking, the intermetallic network structure 108 forms the backbone of the resulting bond lines from any movement during further movement. Compared to using metal powder, the intermetallic network structure 108 or the intermetallic compound network can be generated more uniformly and faster at the atomic level of the dopant (due to larger surface areas or reaction sites). The material of the solder matrix 122 (particularly Sn) is drawn in to form an intermetallic compound surrounding the dopant. This may leave pure tin (e.g., unreacted tin), where Sn enrichment can generally be observed in the bulk solder. Typically, tin can be a major cause of undesirable remelting because other elements are melting elements at high or even higher temperatures. This undesirable remelting phenomenon can be reliably suppressed, particularly by means of the intermetallic network structure 108.

[0097] As described above, a low bonding line thickness can be obtained. Therefore, a short time may be sufficient to homogenize the body solder and dopant. This may be advantageous for forming an intermetallic compound mesh or intermetallic mesh structure 108 that connects the upper and lower contact interfaces in the form of opposite external structures 110, 112 (i.e., on the back side of the die and the surface of the carrier). Advantageously, Sn bonding can occur in the intermetallic compound (promoting the tendency of the intermetallic connection structure 106 not to remelt), which can also play a role in bonding the intermetallic compound mesh.

[0098] Figure 9 A cross-sectional view of an electronic system 100 according to another exemplary embodiment is shown. Figure 9 The vertical thickness of the intermetallic connection structure 106 is very small. Figure 9 In one embodiment, the body 114 is made of copper, the barrier layer 106 is made of nickel, and the intermetallic phase acceleration layer 128 includes palladium and gold as dopants.

[0099] Table 1 shows the results according to... Figure 9 The metal content of various components of the intermetallic connection structure 106 is shown in Table 2. Table 2 summarizes the information from Table 1 and provides an indication of the ratio between the partial weight of the dopant and the total weight of the intermetallic connection structure 106.

[0100] <![CDATA[ Material ]]> <![CDATA[ Total mass [g] ]]> gold <![CDATA[1.158×10 -12 ]]> palladium <![CDATA[9.6×10 -13 ]]> Solder (all) <![CDATA[1.01115×10 -10 ]]> Tin (96% of solder paste) <![CDATA[9.70704×10 -11 ]]> Silver (3% of solder paste) <![CDATA[3.03345×10 -12 ]]> Copper (0.5% of solder paste) <![CDATA[5.05575×10 -13 ]]>

[0101] Table 1

[0102]

[0103] Table 2

[0104] Therefore, Tables 1 and 2 indicate the dopant weight ratio in the solder joint of the intermetallic compound mesh. As shown in the tables, ignoring dopant originating from the back of the chip, the dopant weight ratio across the entire solder joint in the illustrated embodiment is approximately 5.5%.

[0105] Increasing the load of dopant can accelerate the formation of intermetallic compound networks. However, if the rate is too fast, it may cause flux to escape from the bond line (thus reducing the fluidity of the solder material). This can create voids in the bond line. Optimization can be based on (i) reflow process characteristics and (ii) dopant dosage. Typically, the dopant dosage can range from 1% to 35% by weight, and in many cases, excellent results can be obtained in the range of 4.5% to 6.5% by weight.

[0106] In one embodiment, the manufacturing method may include producing an intermetallic connection structure 106 having an intermetallic mesh structure 108 composed of an alloy of tin (Sn) with copper (Cu) and silver (Ag), wherein copper is in the range of 1% to 30% by weight, silver is in the range of 1% to 60% by weight, and preferably the remainder is tin. Thus, the intermetallic mesh structure 108 can be produced from an alloy of Sn with Cu and Ag, wherein Cu ranges from 1% to 30% by weight, and Ag ranges from 1% to 60% by weight (i.e., using an Ag-Cu-Sn solder system).

[0107] Table 3 shows exemplary components of an intermetallic connection structure 106 having an intermetallic mesh structure 108 according to various embodiments (along with solidus temperature). T 固相线 and liquidus temperature T 液相线 ):

[0108]

[0109] Table 3

[0110] Figure 10 A cross-sectional view of an electronic system 100 according to yet another exemplary embodiment is shown. Figure 10 In one embodiment, the formation of a metal mesh structure 108 in a solder matrix 122 is shown, the metal mesh structure 108 extending over almost the entire extensional scale between the carrier 102 and the component 104. Therefore, the outer structures 110, 112 ( Figure 10 The relative vertical extension scale (not shown in the figure) may be very low.

[0111] Figures 11 to 13This is a cross-sectional view of the structure obtained during the manufacture of electronic system 100 according to yet another exemplary embodiment.

[0112] refer to Figure 11 Solder paste 130, including intermetallic particles 132, is applied to the upper main surface of the leadframe carrier 102. Therefore, intelligent selective soldering of the leadframe is possible. For example, a corresponding process can be performed in the laminate with defined pad lines. (See again...) Figure 11 Very small amounts of solder paste 130 can be dispensed. For example, fine solder paste 130, such as type 5 solder paste, can be used.

[0113] refer to Figure 12 Electronic component 104 is pressed from above onto the applied solder paste 130. Therefore, a die bonding process can be performed, and electronic component 104 can be pressed onto solder paste 130 such that the thickness of the deformed solder paste 130 is preferably reduced to a solder ball size. In other words, a single layer 134 of intermetallic particles 132 is formed between the carrier 102 and component 104 by extrusion.

[0114] refer to Figure 13 As mentioned above, for Figure 12 The structure shown is reflow soldered to form an intermetallic connection structure 106 between the carrier 102 and the component 104. Therefore, the reflow process is performed to allow for the formation of a high intermetallic compound (e.g., the target could be 70%).

[0115] Figure 14 Phase diagram 150 illustrates the properties of different intermetallic phases produced by mixing silver, gold, and tin, and is used to explain the principles of an exemplary embodiment.

[0116] The change in mole fraction between silver (Ag) and tin (Sn) is indicated by reference numeral 152. Correspondingly, the change in mole fraction between silver (Ag) and gold (Au) is indicated by reference numeral 154. Furthermore, the change in mole fraction between tin (Sn) and gold (Au) is indicated by reference numeral 157. Phase diagram 150 illustrates the various phases of the gold-silver-tin system. For example, a liquid phase can be obtained in region 159 with a high tin content. In the central region of phase diagram 150, corresponding to reference numeral 160, a high degree of mixing of multiple metallic elements can be achieved. According to an exemplary embodiment, said region can be used to form an intermetallic network structure 108.

[0117] More specifically, an exemplary embodiment may use multiple metallic elements to produce vertically fused intermetallic compounds (or multiple intermetallic compounds). This allows for the formation of an intermetallic compound mesh or intermetallic mesh structure 108 after the reflow process. Advantageously, the intermetallic compound mesh does not remelt during further reflow. Therefore, it is possible to maintain the structural stability of the obtained bond line or intermetallic connection structure 106. Descriptively speaking, the intermetallic connection structure 106 can hold electronic components 104 (particularly silicon chips) on the carrier 102 during reflow. Advantageously, bulk solder clusters may melt during reflow but cannot flow away due to their embedding in the intermetallic compound mesh. Advantageously, the bulk solder (which may be soft and malleable) can balance the stress in the bond line.

[0118] Figure 15 This is a graph 170 illustrating the reflow soldering process performed during the manufacture of electronic system 100 according to an exemplary embodiment. Along the horizontal axis 172, time is plotted in seconds. Along the vertical axis 174, temperature is plotted in °C. Curve 176 shows the high-temperature reflow characteristic curve. As indicated by reference numeral 178, the peak temperature (which can be selected in the range of 280°C to 300°C, e.g., above and below the carrier Tg) is maintained for a relatively long time during reflow soldering, preferably 1 to 2 minutes. With this control scheme, excellent performance can be obtained in forming the intermetallic mesh structure 108 in the intermetallic connection structure 106.

[0119] Figure 16 (First reflux) and Figure 17 (Second Reflow) illustrates a method for manufacturing an electronic system 100 according to an exemplary embodiment. The described reflow characteristic profile reliably prevents unwanted remelting of the solder material. During the described reflow soldering process, the preform of the electronic system 100 to be formed is guided through temperature zones I to VIII with different temperature values, such as... Figure 16 As shown. Referring to reference numeral 190, the preform can be guided through an immersion zone where a solder joint has not yet formed. As shown by reference numeral 192, the preform can then be subjected to increased peak time and temperature, which is beneficial for the growth of intermetallic compounds.

[0120] Subsequently, the processed preform of the electronic system 100 to be formed can undergo a further reflow process. In this case, the preform can be guided through temperature zones 1 to 8 with different temperature values, such as... Figure 17 As shown. According to Figure 17 Another electronic component 104' is attached above electronic component 104 by additional solder paste 130'. Similarly, according to... Figure 17 During the process, the solder of the first component 104 will not remelt in the temperature peak region.

[0121] In the immersion zone 194, the solder joint has not yet formed. In the peak zone 196, the solder melts. In the cooling zone 198, the solder solidifies.

[0122] Figure 18 A cross-sectional view of an electronic system 100, implemented as a transistor outline (TO) package, is shown according to an exemplary embodiment. The electronic system 100 is mounted on a mounting structure 182, implemented here as a printed circuit board, for establishing a device 180.

[0123] Mounting structure 182 includes an electrical contact 184, which is implemented as a plated portion in a through hole of mounting structure 182. When electronic system 100 is mounted on mounting structure 182, electronic components 104 of electronic system 100 are electrically connected to electrical contact 184 via conductive carrier 102 of lead frame made of copper implemented here in electronic system 100.

[0124] Therefore, the electronic system 100 includes a conductive carrier 102, electronic components 104 (implemented herein as power semiconductor chips) mounted on the carrier 102 via an intermetallic connection structure 106, and encapsulation material 156 encapsulating a portion of the carrier 102 and the electronic components 104. Figure 18 It can be seen that the pads on the upper main surface of the electronic component 104 are electrically coupled to the carrier 102 via connecting wires that serve as conductive contact elements 160.

[0125] During operation of the power electronic system or electronic system 100, the power semiconductor chip in the form of electronic component 104 generates a significant amount of heat. Simultaneously, it should be ensured that any undesired current flow between the bottom surface of electronic system 100 and the environment is reliably avoided.

[0126] To ensure electrical insulation of electronic component 104 and remove heat from inside electronic component 104 to the environment, an electrically insulating and thermally conductive interface structure 158 can be provided, which covers the exposed surface portion of carrier 102 and the connection surface portion of encapsulation material 156 at the bottom of electronic system 100. The electrical insulation properties of interface structure 108 prevent unwanted current flow even when there is a high voltage between the inside and outside of electronic system 100. The thermal conductivity properties of interface structure 158 facilitate heat dissipation from electronic component 104 via conductive carrier 102 (made of appropriately thermally conductive copper), through interface structure 108, and toward heat sink 162. Heat sink 162, which may be made of a highly thermally conductive material, such as copper or aluminum, has a base 164 directly connected to interface structure 158 and has a plurality of heat sinks 166 extending from base 164 and parallel to each other to remove heat to the environment.

[0127] like Figure 18 As shown, the intermetallic connection structure 106 is formed between the carrier 102 and the component 104, for example, implemented as follows: Figure 1 As shown.

[0128] It should be noted that the term "comprising" does not exclude other elements or features, and "a" or "one" does not exclude multiple. Elements described in different embodiments may also be combined. It should also be noted that reference numerals in the drawings should not be construed as limiting the scope of the claims. Furthermore, the scope of this application is not intended to be limited to specific embodiments of the processes, machines, manufactures, compositions of matter, apparatuses, methods, and steps described in the specification. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps within their scope.

Claims

1. An electronic system (100), wherein, The electronic system (100) includes: A carrier that is at least partially conductive (102); Electronic components (104); and An intermetallic connection structure (106) connecting a carrier (102) and an electronic component (104) and including: An intermetallic mesh structure (108) is located in the central part of the intermetallic connection structure (106), the intermetallic mesh structure (108) comprising a plurality of interconnected filaments, each filament being formed by a sequence of directly connected metal particles of at least three different metal chemical elements; A metallic matrix composed of another metallic material, said other metallic material being different from the at least three different metallic chemical elements; and The opposite external structures (110, 112), which have no intermetallic mesh and are respectively arranged between the intermetallic mesh structure (108) and the carrier (102) and the electronic component (104), the filaments being embedded in the metal matrix and forming a continuous conductive vertical path between the opposite external structures in order to electrically connect the electronic component to the carrier.

2. The electronic system (100) according to claim 1, wherein, The carrier (102) includes a lead frame structure.

3. The electronic system (100) according to claim 1 or 2, wherein, The carrier (102) includes a conductive body (114) partially covered by a metal diffusion barrier layer (116).

4. The electronic system (100) according to claim 1 or 2, wherein, The electronic component (104) includes a semiconductor body (118) covered with a back metallization (120) connected to an intermetallic connection structure (106).

5. The electronic system (100) according to claim 1 or 2, wherein, The intermetallic connection structure (106) includes a solder matrix (122) for generating solder connections between the electronic component (104) and the carrier (102).

6. The electronic system (100) according to claim 5, wherein, The solder matrix (122) comprises tin.

7. The electronic system (100) according to any one of claims 1-2 and 6, wherein, The intermetallic connection structure (106) includes at least one intermetallic phase promoter particle (124) composed of an intermetallic phase promoter metal, for promoting the formation of intermetallic phases within the intermetallic connection structure (106).

8. The electronic system (100) according to claim 7, wherein, The at least one intermetallic phase promoter metal includes at least one from the group consisting of silver and copper.

9. The electronic system (100) according to any one of claims 1-2, 6, and 8, wherein, The intermetallic mesh structure (108) and the external structure (110, 112) comprise the same intermetallic material.

10. The electronic system (100) according to any one of claims 1-2, 6, and 8, wherein, The electronic system includes at least one of the following features: The intermetallic connection structure (106) includes at least one intermetallic phase accelerating metal composed of intermetallic phase accelerating particles (126) for accelerating the formation of the intermetallic network structure (108); The intermetallic connection structure (106) is lead-free; The vertical thickness (D) of the intermetallic connection structure (106) is in the range of 5 μm to 50 μm; The electronic system includes at least one intermetallic phase acceleration layer (128) made of intermetallic phase acceleration metal, which is used to accelerate the formation of intermetallic mesh structure (108) and is arranged between the carrier (102) and the intermetallic connection structure (106). The partial vertical thickness of the intermetallic mesh structure (108) is at least 80% of the total vertical thickness (D) of the entire intermetallic connection structure (106); The intermetallic mesh structure (108) is formed as a branched network of interconnected multimetallic particles that extends continuously across the entire vertical spacing between the outer structures (110, 112). The weight percentage of the intermetallic mesh structure (108) relative to the entire intermetallic connection structure (106) is in the range of 1% to 30% by weight. The intermetallic connection structure (106) has an intermetallic mesh structure (108) comprising alloyed components of tin, copper and silver, wherein the weight percentage of copper is from 1% to 30% and the weight percentage of silver is from 1% to 60%.

11. The electronic system (100) according to claim 10, wherein, The electronic system includes at least one of the following features: The at least one intermetallic phase-accelerating metal includes at least one from the group consisting of palladium, gold, platinum, vanadium, and zinc; The vertical thickness (D) of the intermetallic connection structure (106) is in the range of 10 μm to 30 μm; The intermetallic phase acceleration layer (128) can be a single layer or a double layer; The weight percentage of the intermetallic mesh structure (108) relative to the entire intermetallic connection structure (106) is in the range of 3% to 8% by weight. The intermetallic connection structure (106) has an intermetallic mesh structure (108) comprising an alloy of tin, copper and silver, wherein the weight percentage of copper is 1% to 30%, the weight percentage of silver is 1% to 60%, and the remainder is tin.

12. The electronic system (100) according to claim 10, wherein, The electronic system includes at least one of the following features: The vertical thickness (D) of the intermetallic connection structure (106) is in the range of 10 μm to 20 μm; The weight percentage of the intermetallic mesh structure (108) relative to the entire intermetallic connection structure (106) is in the range of 4.5% to 6.5% by weight.

13. A method for manufacturing an electronic system (100), wherein, The method includes: The carrier (102), which is at least partially conductive, is connected to the electronic component (104) via an intermetallic connection structure (106); and An intermetallic connection structure (106) is formed, the intermetallic connection structure (106) having: An intermetallic mesh structure (108) is located in the central part of the intermetallic connection structure (106), the intermetallic mesh structure (108) comprising a plurality of interconnected filaments, each filament being formed by a sequence of directly connected metal particles of at least three different metal chemical elements; A metallic matrix composed of another metallic material, said other metallic material being different from the at least three different metallic chemical elements; and The opposite external structures (110, 112), which have no intermetallic mesh and are respectively arranged between the intermetallic mesh structure (108) and the carrier (102) and the electronic component (104), the filaments being embedded in the metal matrix and forming a continuous conductive vertical path between the opposite external structures in order to electrically connect the electronic component to the carrier.

14. The method according to claim 13, wherein, The method includes forming an intermetallic connection structure (106) by applying solder paste (130) to a carrier (102), the solder paste (130) comprising a solder matrix (122) for forming a solder joint between an electronic component (104) and the carrier (102) and intermetallic phase promoter particles (124) of at least one intermetallic phase promoter metal for promoting the formation of intermetallic phases within the intermetallic connection structure (106).

15. The method according to claim 14, wherein, The method includes providing solder paste (130) with intermetallic particles (132) having a diameter (d) in the range of 5 μm to 50 μm.

16. The method according to claim 15, wherein, The method includes providing solder paste (130) with intermetallic particles (132) having a diameter (d) in the range of 10 μm to 20 μm.

17. The method according to any one of claims 14-16, wherein, The method includes: extruding solder paste (130) between a carrier (102) and an electronic component (104).

18. The method according to claim 17, wherein, The method includes extruding solder paste (130) to form a monolayer (134) of intermetallic particles (132) of solder paste (130) between a carrier (102) and an electronic component (104).

19. The method according to any one of claims 14-16, 18, wherein, The method includes at least one of the following features: The method includes: covering a carrier (102) with an intermetallic phase acceleration layer (128) to accelerate the formation of an intermetallic mesh structure (108), and arranging the intermetallic phase acceleration layer (128) between the carrier (102) and the solder paste (130). Provide intermetallic phase accelerating particles (126) to the solder paste (130) to accelerate the formation of the intermetallic network structure (108); The method includes producing an intermetallic connection structure (106) having an intermetallic mesh structure (108) composed of tin alloyed with copper and silver, wherein copper is in the range of 1% to 30% by weight and silver is in the range of 1% to 60% by weight.

20. The method according to claim 19, wherein, The method includes the following features: The method includes producing an intermetallic connection structure (106) having an intermetallic mesh structure (108) composed of tin alloyed with copper and silver, wherein copper is in the range of 1% to 30% by weight, silver is in the range of 1% to 60% by weight, and the remainder is tin.

21. The method according to any one of claims 13-16, 18, wherein, The method includes forming the intermetallic connection structure (106) by heating the precursor of the intermetallic connection structure (106) to a peak temperature that is higher than the melting temperature of the solder precursor but lower than the melting temperature of the intermetallic mesh precursor.

22. The method according to claim 21, wherein, The method includes maintaining the peak temperature for a period of at least 1 minute.

23. The method according to claim 22, wherein, The method includes maintaining the peak temperature for a period of time ranging from 1 minute to 4 minutes.

24. The method according to claim 22, wherein, The method includes maintaining the peak temperature for a period of time ranging from 1.5 minutes to 2 minutes.

25. The method according to any one of claims 22-24, wherein, The method includes at least one of the following features: The peak temperature is in the range of 260°C to 350°C; The melting temperature of the solder precursor is below 240℃; The melting temperature of the intermetallic mesh precursor is at least 370°C.

26. The method of claim 25, wherein, The method includes the following features: The peak temperature is in the range of 280°C to 300°C.

27. The method according to any one of claims 13-16, 18, 20, 22-24, wherein, The method includes forming the intermetallic connection structure (106) by reflow soldering.

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