Systems for packaging power modules

Abstract

System, comprehensive: a multitude of bonds coupled to a perimeter of a substrate; and a molding compound that covers a surface of the substrate and fills openings between the loops of the multitude of bonds and the substrate.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] The present application claims priority over U.S. Preliminary Application No. 63 / 745,205 entitled “SYSTEMS FOR POWER MODULE PACKAGING”, which was filed on January 14, 2025. The entire content of the aforementioned application is hereby incorporated by reference for all purposes. TECHNICAL AREA

[0002] The present description refers generally to the packaging of power modules and in particular to the plastic encapsulation of chips on a substrate. BACKGROUND AND DETOUR

[0003] Direct bonded copper substrates (DBCs) are used in the power semiconductor industry. An encapsulation material can be bonded to the DBC and used to cover chips, power and signal connections, and the perimeter of a heat exchange surface of a power module. Bonding the encapsulation material to the substrate can be time-consuming and difficult due to the fragile materials associated with the power module.

[0004] Therefore, a method for developing a DBC-based power module with a plastic chip encapsulation is required. In one example, a system comprises a multitude of bonds coupled to a substrate perimeter and a molding compound that covers a surface of the substrate and fills openings between loops of the multitude of bonds and the substrate.

[0005] It should be noted that the foregoing summary serves to present, in simplified form, a selection of concepts that are further explained in the detailed description. It does not serve to identify essential features of the claimed subject matter, the scope of which is defined exclusively by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to implementations that eliminate the disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE FIGURES

[0006] The above advantages, as well as further advantages of the present disclosure, will be readily apparent to those skilled in the art from the following detailed description when viewed in light of the accompanying drawings, which are as follows: The Fig. 1A, Fig. 1B and Fig. Figure 1C shows the phase of bonding on the DBC substrate during the manufacturing process of a power module; Fig. 2 shows a binding with loops; Fig. 3A shows an encapsulated module; Fig. Figure 3B shows the interior of the encapsulated module; Fig. Figure 3C shows a cross-sectional view of the encapsulated module; Fig. Figure 4A shows a perspective view of the encapsulated module with a heat sink; Fig. Figure 4B shows a sectional view of the encapsulated module including the heat sink; Fig. Figure 5 shows an example of the thickness of the substrate of the power module; and Fig. Figure 6 shows an example of a gap between an encapsulation plane and a contact plane between the DBC and the heat sink. DETAILED DESCRIPTION

[0007] The following description relates to a power module. The disclosure addresses the challenge of plastic chip encapsulation for power modules based on directly bonded copper ceramic (DBC) substrates, which are inherently more fragile than metallic substrates and cannot be easily processed using conventional encapsulation techniques. Conventional packaging solutions often require the creation of holes or anchoring edges in the substrate material, which can compromise the structural integrity of ceramic-based modules. Furthermore, conventional encapsulation methods can negatively affect the heat exchange capacity of the power module due to limitations imposed by the anchoring method, and the highly exothermic curing reaction of epoxy molding compounds can lead to thermal damage if not adequately controlled.

[0008] The proposed solution introduces a novel anchoring method for the molding compound, employing wire or tape bonding techniques already used in the standard production process of electronic power modules. The process can comprise two steps. First, during the bonding phase, the DBC substrate is provided with an outer circumferential area where bonds are created using either wire or tape bonding techniques, including stitch bonding. Second, during the molding phase, the epoxy resin molding compound covers the entire surface of the DBC along with its components and electrical connections, flows into the loops formed by the circumferential bonds, and solidifies there, creating a secure anchorage through the tensile and shear strength of the bond itself.

[0009] This innovative approach offers several significant technical advantages. The process reduces the mechanical stress on the ceramic substrate and is therefore particularly suitable for sensitive DBC-based power modules. It optimizes the layout and geometry of the DBC by eliminating the need for anchor points, such as holes, while simultaneously providing high anchorage strength through the weld resistance of the bonds. The solution ensures optimal thermal contact between the outer copper layer of the DBC and the heat sink by anchoring the molding compound internally through the bonds, thus eliminating the need for retention via the outer geometry and preventing the plastic encapsulation from interfering with the dissipative pad contact.Furthermore, the bonds themselves act as heat dissipation pathways, reducing the temperature of the power module both during the forming phase and in operation, with the ribbon bonds enabling even greater heat dissipation due to their larger surface area. The disclosure also allows for the strategic placement of bonds at thermally critical points beyond the circumference, further improving the thermal management of hot spots within the power module.

[0010] The Fig. 1A, Fig. 1B and Fig. Figure 1C shows the phase of bonding on the DBC substrate during the manufacturing process of a power module. Fig. Figure 2 shows a binding with loops. Fig. 3A shows an encapsulated module. Fig. Figure 3B shows the interior of the encapsulated module. Fig. 3C shows a cross-sectional view of the encapsulated module. Fig. Figure 4A shows a perspective view of the encapsulated module with a heat sink. Fig. Figure 4B shows a sectional view of the encapsulated module including the heat sink. Fig. Figure 5 shows an example of the thickness of the substrate of the power module. Fig. Figure 6 shows an example of a gap between an encapsulation plane and a contact plane between the DBC and the heat sink.

[0011] In one example, the power module of this disclosure can include a plastic chip encapsulation made of direct copper bonding (DBC) using bonds. A plastic package (e.g., an encapsulation) is clamped to a power module on a DBC substrate by bonds. The bonds can be tape or wire bonds, which are described below. The mechanical strength and heat transfer of the power module can be improved by the methods described here.

[0012] The DBC substrate can be manufactured according to the design requirements of the chips and surface-mount devices (SMDs). The dies and SMDs can be bonded to the DBC using wire, tape, or stitch bonding. The DBC can be provided with a perimeter to create a surface onto which further wire, tape, or stitch bonds can be applied to bond the encapsulation material to the DBC. This eliminates the need for new tooling during the encapsulation process.

[0013] During the molding phase, a molding compound can cover the entire surface of the DBC, including its components (e.g., the dies and SMDs). The molding compound can flow until it solidifies. It can also flow into the gaps created by the bonds around the perimeter of the DBC, forming a multitude of anchors. Co-molding between the molding compound and the bonding wires can result in increased strength due to the tensile and shear strength of the bonds.

[0014] The wire or tape bonding technique used for encapsulation may already be employed in the manufacturing of the power module. Therefore, no new processes and / or manufacturing techniques are used when applying the methods and systems described here.

[0015] The housing of the power module can be designed to dissipate heat. The heat dissipation of the molding compound can be relatively low. Previous examples include the addition of fillers and / or other additives to increase thermal conductivity. In the present disclosure, additives and fillers can be avoided by using bonding agents. The bonding agents can reduce the module's temperature both during the molding phase and during operation. Thus, the bonding agents can be applied to thermal hot spots on the circumference and in areas other than the circumference. In this way, the disclosure provides support for a power module that incorporates a manufacturing process with a reduced number of tools and materials, thereby reducing costs and increasing efficiency in the production of the power module.

[0016] Fig. Figure 1A-6 shows example configurations with the relative arrangement of the various components. If these elements are in direct contact with each other or directly coupled, they can be described as being in direct contact or directly coupled, respectively, in at least one example. Similarly, elements shown side by side or adjacent to each other can be described as being adjacent to each other or adjacent to each other, respectively, in at least one example. For instance, components that are in planar contact with each other can be described as being in planar contact. As another example, elements that are separated only by a gap and have no other components can be described as such in at least one example. In yet another example, elements that are shown above / below each other, on opposite sides, or to the left / right of each other can be described as such, relative to each other.Furthermore, in at least one example, as illustrated in the figures, a topmost element or the highest point of an element can be referred to as the "top" of the component, and a bottommost element or the lowest point of the element can be referred to as the "bottom" of the component. The terms top / bottom, upper / lower, above / below used here can refer to a vertical axis of the figures and can be used to describe the arrangement of elements within the figures relative to one another. For example, in one instance, elements shown above other elements are arranged vertically above the other elements. As another example, the shapes of the elements depicted in the figures can be described as such (e.g., circular, straight, flat, curved, rounded, beveled, angled, etc.).Furthermore, the depicted elements that intersect each other may be referred to as intersecting elements or mutually intersecting elements in at least one example. Furthermore, an element shown within another element or shown outside another element may be referred to as such in one example. It is understood that one or more components described as "substantially similar and / or identical" may differ from each other according to manufacturing tolerances (e.g., within a deviation of 1-5%). Fig. Figures 1A-6 are shown approximately to scale.

[0017] Fig. Figure 1A shows the bonding phase of a DBC substrate 100. The DBC substrate 100 can comprise a primary body 102 and a perimeter 104. The primary body 102 and the perimeter 104 can be separate parts with a gap (e.g., a trough) 108 between them. In one example, the primary body 102 and the perimeter 104 can be insulated parts on an upper copper layer of the DBC substrate 100. The DBC substrate 100 can be coupled to a base 106. The gap 108 can correspond to a region of the base 106 that is exposed between the perimeter 104 and the primary body 102.

[0018] An axis system 190 with three axes is shown: an x-axis parallel to a horizontal direction, a y-axis parallel to a vertical direction, and a z-axis perpendicular to each of the x- and y-axes. The primary body 102 and the perimeter 104 can have identical heights, measured along the y-axis.

[0019] Fig. Figure 1B shows an application 120 with a multitude of bonds 130. An applicator 122 can eject the multitude of bonds 130 along the perimeter 104 of the DBC substrate 100. In one example, the multitude of bonds 130 can be applied in segments. Each of the segments can contain loops and linear parts that are in Fig. 2 are described in more detail. The multitude of bindings 130 can comprise a multitude of loops and linear segments, with the multitude of loops extending along the y-axis away from the circumference 104.

[0020] Fig. Figure 1C shows a final product 140 of the adhesive phase with a plurality of bonds 130 bonded to the circumference 104. More precisely, the multiple bonds 130 are attached to a side of the circumference 104 facing away from the base 106. In some examples, the majority of the bonds 130 can additionally or alternatively be applied to the primary body 102. The locations where the multiple bonds 130 can be applied to the primary body 102 can correspond to areas susceptible to elevated temperatures.

[0021] Fig. Figure 2 shows an embodiment of a segment 200 of the plurality of bonds 130. The segment 200 can contain a first linear part 202. The first linear part 202 can be in planar contact with the circumference 104 along its entire length and run parallel to it. In one example, each segment 200 can contain at least one loop or semicircle arranged between two linear segments. Each of the plurality of bonds can be spaced apart from adjacent bonds of the plurality of bonds 120. In other examples, the plurality of bonds can be adjacent to one another, such that the bonds touch adjacent bonds.

[0022] Segment 200 can also contain a first semicircle 204. The first semicircle 204 can be raised along the y-axis relative to the circumference 104, so that a first opening 205 is located between the first semicircle 204 and the circumference 104. In one example, the first semicircle 204 is a first loop.

[0023] A second linear section 206 can be connected to the first semicircle 204. In this way, the first semicircle 204 can be clamped between the first linear section 202 and the second linear section 206. The second linear section 206 can be in full contact with the circumference 104 along its entire length and run parallel to it. In one example, the length of the second linear section 206 can be identical or different from the length of the first linear section 202.

[0024] Segment 200 can also contain a second semicircle 208. The second semicircle 208 can be connected to the second linear part 206. In this way, the second linear part 206 can be positioned between the first semicircle 204 and the second semicircle 208. The second semicircle 208 can be raised relative to the circumference 104, so that a second opening 207 is located between the second semicircle 208 and the circumference 104. In one example, the size of the second opening 207 can be essentially identical to the size of the first opening 205. In another example, the second semicircle 208 is a second loop.

[0025] A third linear section 210 can be connected to the second semicircle 208. In this way, the second semicircle 208 can be clamped between the second linear section 206 and the third linear section 210. The third linear section 210 can be in full contact with the circumference 104 along its entire length and run parallel to it. In one example, the length of the third linear section 210 can be identical to or different from the lengths of the first linear section 202 and the second linear section 206.

[0026] In one example, the entirety of segment 200 can be a single piece. For instance, a single bond wire or bond tape can form the first linear part 202, the first semicircle 204, the second linear part 206, the second semicircle 208, and the third linear part 210.

[0027] Spaces can be arranged between adjacent segments of the plurality of bonds 130. For example, a first space 212 can be arranged between the first linear part 202 and an adjacent segment of the plurality of bonds 130. A second space 214 can be arranged between the third linear part 210 and an adjacent segment of the plurality of bonds 130.

[0028] Segment 200 can have a uniform diameter along its entire length, including all linear segments and loops. Additionally or alternatively, sections of the linear segments can have a smaller diameter than the loops due to the bonding. Additionally or alternatively, the linear segments can have a flat surface in the areas with reduced diameter.

[0029] Fig. Figure 3A shows an example of an encapsulated power module 300. The power module can be covered by a capsule 302. The encapsulation material 302 can be an epoxy resin. In one example, the encapsulation material 302 does not touch a side of the base 106 to which the perimeter 104 and the primary body are not coupled. The side of the base 106 free from the encapsulation 302 can be exposed or coupled to an additional element 222. The additional element 222 can be a substrate, a dissipative plate, or another feature. Fig. Figure 3B shows a transparent view 325 of the encapsulated power module. The transparent view 325 shows a variety of bonds 330 that are coupled to a component of the power module on the primary body, such as an SMD of the power module. Fig. Figure 3C shows a sectional view 350 of the encapsulated power module 300. In this view, the encapsulation material 302 completely surrounds each of the numerous bonds 130. In one example, a molding compound that hardens to form the encapsulation material 302 can flow into the openings corresponding to the semicircles of the segments of the multitude of bonds. The molding compound can flow over the entire surface of the DBC, along with the components mounted on it, and through the openings formed by the semicircles of the multitude of bonds. The molding compound can harden, thus creating an anchor for the encapsulation material. In this way, the encapsulation material 302 can be a single solid piece, as shown in Figure 3. Fig. 3C shown, which connects to the surfaces of the power module and the surfaces of the multiple bonds 130 and the multiple bonds 330.

[0030] The curing of the molding compound can involve an exothermic reaction. Curing may require keeping this exothermic reaction within a desired temperature range to prevent the power module from exceeding a threshold temperature. The numerous bonds can enhance heat dissipation, thus preventing thermal damage during the curing of the molding compound and during the operation of the power module.

[0031] The dimensions of the encapsulation 302 can be larger than the base 106 and the circumference 104 along the x, y, and z axes. As in Fig. As shown in Figure 3C, part 352 of the encapsulation 302 projects beyond and extends beyond the profiles of the circumference 104 and the substrate 106.

[0032] The Fig. 4A and Fig. Figure 4B shows embodiments 400 and 450 of a dissipative plate 410 coupled to the DBC 100. The dissipative plate 410 can be coupled to a side of the DBC 100 that faces the plurality of bonds 130 and other components. The dissipative plate 410 can here be interchangeably referred to as a heat sink 410.

[0033] The dissipative plate 410 can contain a plurality of fins 412. The plurality of fins 412 can be arranged on a first side of the dissipative plate 410. The DBC 100 can be coupled to a second side of the dissipative plate 410, with the second side facing the first. The plurality of fins 412 can increase the cooling capacity of the dissipative plate 410.

[0034] Fig. Figure 5 shows an embodiment 500 of the DBC 100 with a circumference 104, a base 106, and a dissipative plate 522. In one example, the dissipative plate 522 is made of copper and is configured as the bottom layer of the DBC 100. The dissipative plate 522 can facilitate heat transfer between an outer layer of the DBC 100 and the heat sink 410. The thickness 502 of the dissipative plate 522, measured along the y-axis, can be between 0.1 and 1.0 mm. In one example, the thickness 502 is exactly 0.3 mm.

[0035] Fig.Figure 6 shows an embodiment 600 of the DBC 100 in thermal contact with the heat sink 410. The DBC 100 can be in thermal contact with the heat sink 410 via internal anchoring by the molding compound and the plurality of bonds. Thus, no external anchoring and / or coupling is required for the encapsulation, and the thermal properties of the power module can be improved compared to other examples. In one example, the encapsulation 302 can be located at a distance corresponding to the thickness 502 of the dissipative plate 522. The distance can be less than 1 mm. In some examples, the distance can additionally or alternatively be less than 0.5 mm. In one example, the distance is 0.3 mm. The DBC 100, including the encapsulation 302 and all other components of the DBC 100, is spaced from the heat sink 410 via the dissipative plate 222.

[0036] In this way, a plastic chip encapsulation process for a power module based on a DBC substrate can exhibit increased robustness and thermal performance. By using bonds to anchor the molding compound to the substrate, less stress can be exerted on the substrate, which may be more suitable for power modules mounted on a ceramic and / or non-metallic base, which is more fragile. The DBC layout can be optimized because anchoring points can be avoided, reducing manufacturing time and costs. The anchoring strength provided by the bonds is relatively high, and the bonds also allow a dissipative plate of the DBC to come into direct contact with a heat sink due to the elimination of external coupling points. This reduces the temperature of the power module during the manufacturing process and during operation.

[0037] The disclosure also provides support for a system with a plurality of bonds coupled to a perimeter of a substrate and a molding compound that covers a surface of the substrate and fills openings between loops of the plurality of bonds and the substrate. In a first example of the system, the molding compound covers the plurality of bonds. In a second example of the system, which may optionally include the first example, the substrate is a ceramic substrate. In a third example of the system, which may optionally include one or both of the first and second examples, the substrate is nonmetallic. In a fourth example of the system, which may optionally include one or more or each of the first through third examples, the substrate is directly bonded copper (DBC).In a fifth example of the system, which optionally includes one or more or any of the first four examples, the perimeter extends around a primary body of the substrate, and bonds of the plurality of bonds are coupled to the primary body. In a sixth example of the system, which optionally includes one or more or any of the first five examples, the plurality of bonds is arranged in segments, each segment comprising multiple loops and linear parts, with the loops and linear parts alternating along each segment.

[0038] The disclosure also provides support for a system for a power module comprising a substrate with a primary body and a perimeter, a plurality of bonds coupled to the perimeter, the plurality of bonds being subdivided into segments, each segment comprising a plurality of loops and a plurality of linear parts, and a molding compound covering a surface of the substrate and filling openings between loops of the plurality of bonds and the substrate. In a first example of the system, each segment comprises at least two loops alternating with linear parts. In a second example of the system, which may optionally include the first example, each loop is raised above the surface of the substrate. In a third example of the system, which may optionally include one or both of the first and second examples, each segment is spaced apart from an adjacent segment.In a fourth example of the system, which optionally includes one or more or each of the first three examples, the majority of the bonds are wire or tape bonds, and each segment is a continuous piece of wire or tape bond. In a fifth example of the system, which optionally includes one or more or each of the first four examples, the molding compound is epoxy. In a sixth example of the system, which optionally includes one or more or each of the first five examples, the substrate is coupled to a first side of a base, and a dissipative plate is coupled to a second side of the base. In a seventh example of the system, which optionally includes one or more or each of the first six examples, the dissipative plate is in planar contact with a heat sink.

[0039] The disclosure also provides support for a system comprising a base coupled to a substrate and a plurality of bonds coupled to a surface of the substrate opposite the base, each of the plurality of bonds comprising at least one semicircle arranged between two linear parts. In a first example of the system, an opening is arranged between the at least one semicircle and the surface of the substrate. In a second example of the system, which optionally includes the first example, an encapsulating material covers the base, the substrate, and the plurality of bonds, and the encapsulating material fills the openings between the at least one semicircle and the surface of the substrate. In a third example of the system, which optionally includes one or both of the first and second examples, a dissipative plate is coupled to a surface of the base.In a fourth example of the system, which may optionally include one or more or each of the first three examples, each of the plurality of bonds is spaced apart from neighboring bonds of the plurality of bonds. The term "approximately" means, unless otherwise specified, plus or minus five percent of the range.

[0040] The following claims specifically indicate certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims are to be understood as including one or more such elements, with two or more such elements neither required nor excluded. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether they have a broader, narrower, the same, or different scope than the original claims, are also considered to be included in the subject matter of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 745,205

[0001]

Claims

[1] System, encompassing: a multitude of bonds coupled to a perimeter of a substrate; and a molding compound that covers a surface of the substrate and fills openings between the loops of the multitude of bonds and the substrate. [2] System according to claim 1, wherein the molding compound covers the plurality of bonds. [3] System according to any of the preceding claims, wherein the substrate is a ceramic substrate. [4] System according to any of the preceding claims, wherein the substrate is non-metallic. [5] System according to any of the preceding claims, wherein the substrate is directly bonded copper (DBC). [6] System according to one of the preceding claims, wherein the perimeter extends around a primary body of the substrate and wherein the bonds of the plurality of bonds are connected to the primary body. [7] System according to any of the preceding claims, wherein the plurality of bonds is arranged in segments, each segment comprising several loops and linear parts, the loops and the linear parts alternating along each segment. [8] System for a power module, comprising: a substrate comprising a primary body and a perimeter; a multitude of bonds coupled to the circumference, wherein the multitude of bonds is divided into segments, each segment comprising a multitude of loops and a multitude of linear parts; and a molding compound that covers a surface of the substrate and fills openings between the loops of the multitude of bonds and the substrate. [9] System according to claim 8, wherein each segment comprises at least two loops alternating with linear parts. [10] System according to claim 8 or 9, wherein each loop is raised above the surface of the substrate. [11] System according to any one of claims 8 to 10, wherein each segment is spaced apart from an adjacent segment. [12] System according to any one of claims 8 to 11, wherein the plurality of bindings is a wire binding or a tape binding and wherein each segment is a continuous piece of the wire binding or the tape binding. [13] System according to any one of claims 8 to 12, wherein the molding compound is epoxy. [14] System according to any one of claims 8 to 13, wherein the substrate is connected to a first side of a base and a dissipative plate is connected to a second side of the base. [15] System according to claim 14, wherein the dissipative plate is in planar contact with a heat sink.

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