Electronic component

Abstract

The invention relates to an electronic assembly. An electronic component includes an integrated circuit chip and a package surrounding the integrated circuit chip. The electronic component includes a first conductive region at least partially coating a side of the integrated circuit chip. The first conductive region includes an alloy mainly including bismuth.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to French patent application No. 23 / 09779, filed on September 15, 2023, entitled “Composantélectronique,” ​​which is hereby incorporated by reference to the maximum extent permitted by law. Technical Field

[0003] The present disclosure relates generally to electronic assemblies and processes for making the same, and more particularly, to electronic assemblies including at least one packaged integrated circuit chip, and processes for making such assemblies. Background Art

[0004] Electronic components including at least one packaged integrated circuit chip have been proposed. In particular, there are components including chip scale packages (CSP). These components are usually surface mounted on a printed circuit board using a solder soldering process, which involves melting and then solidifying a solder paste or flux based on a lead-free alloy (such as a tin-silver-copper alloy (Sn-Ag-Cu alloy), also referred to as SAC). In order to assemble the electronic component to the printed circuit board, a temperature above the melting point of the alloy (approximately equal to 218° C. for SAC alloys) is applied to melt the solder material. The component is then cooled to solidify the solder material, thereby mechanically fixing the component to the board.

[0005] However, existing electronic assemblies including CSP packages have various disadvantages. In particular, known processes for manufacturing electronic assemblies using SAC alloys cause problems with undesirable bridging or interconnection between adjacent integrated circuit chips during the solder material reflow step prior to the dicing step intended to singulate the integrated circuit chips.

[0006] Furthermore, in certain applications such as automotive manufacturing, it is desirable to have components with wettable flanks to facilitate inspection steps after soldering. However, during assembly, the reflow step for the SAC alloy coated flanks will cause the alloy to undesirably slip or flow onto the printed circuit board.

[0007] Furthermore, where a component package surrounds several integrated circuit chips (including, for example, ASIC (Application Specific Integrated Circuit) chips) stacked and interconnected by solder balls, these balls are typically made of a metal alloy (e.g., gold-tin alloy) having a higher melting point than the alloy used for soldering (e.g., SAC alloy) to prevent the solder balls from reflowing when the component is soldered to the board. Since gold-tin alloy is particularly expensive, it is desirable to find a lower cost alternative material. Summary of the invention

[0008] Embodiments of the present disclosure overcome some or all of the disadvantages of known electronic components and their manufacturing processes.

[0009] One embodiment provides an electronic component, comprising:

[0010] Integrated circuit chips;

[0011] The packaging surrounding the integrated circuit chip; and

[0012] At least a first conductive region at least partially coats one side of the integrated circuit chip, the first conductive region comprising an alloy primarily comprising bismuth.

[0013] According to one embodiment, the alloy has a bismuth content exceeding 80%, preferably equal to about 90%.

[0014] According to one embodiment, the alloy further includes at least one additional element selected from silver, nickel and tin.

[0015] According to one embodiment, the alloy has a content of said at least one additional element less than 10%, preferably equal to about 5%.

[0016] According to one embodiment, the alloy has:

[0017] Bismuth content equal to about 90%;

[0018] A silver content equal to about 5%; and

[0019] This equates to a nickel content of approximately 5%.

[0020] According to one embodiment, the alloy has a melting point between 270 and 290°C.

[0021] One embodiment provides an electronic device, including:

[0022] support and interconnect substrates;

[0023] at least one contact-forming element located on one face of said support and interconnect substrate;

[0024] at least one electronic component (such as described); and

[0025] At least one second electrically conductive region is interposed between the at least one contact-forming element and the at least one first electrically conductive region of the electronic component.

[0026] According to one embodiment, the second conductive region covers a side surface of the electronic component.

[0027] According to one embodiment, the second conductive region is made of an alloy of tin, silver and copper.

[0028] One embodiment provides a motor vehicle comprising at least one device such as described.

[0029] One embodiment provides a method of manufacturing an electronic component including an integrated circuit chip and a package surrounding the integrated circuit chip, the method comprising the steps of at least partially coating a face of the integrated circuit chip with a first conductive region, the first conductive region comprising an alloy primarily containing bismuth.

[0030] In one embodiment, an electronic device includes an integrated circuit chip, a package surrounding the integrated circuit chip, and at least a first conductive region at least partially coating a side of the integrated circuit chip, the first conductive region including an alloy having at least 50% bismuth.

[0031] In one embodiment, a method includes surrounding an integrated circuit chip with a package. Surrounding the integrated circuit chip with the package includes: at least partially coating a front side of the integrated circuit chip with a first conductive region, the first conductive region including an alloy having at least 50% bismuth, and forming an encapsulation layer on a sidewall and a back side of the integrated circuit chip.

[0032] In one embodiment, a motor vehicle includes an electronic device, the electronic device including a substrate and a package on the substrate. The package includes: an integrated circuit chip, an encapsulation layer on a first side and sidewalls of the integrated circuit chip, and a first conductive region at least partially coating a second side of the integrated circuit chip, the first conductive region including an alloy having at least 50% bismuth. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] These and other features and advantages will be described in detail in the following non-limiting description of specific embodiments in conjunction with the accompanying drawings, in which:

[0034] Figure 1A , Figure 1B , Figure 1C , Figure 1D and Figure 1E is a schematic partial cross-sectional view showing successive steps in a process of manufacturing an electronic assembly according to one embodiment; and

[0035] Figure 2 is a partial schematic cross-sectional view of an electronic device including an electronic component according to one embodiment. DETAILED DESCRIPTION

[0036] Similar features are designated with similar reference numerals in the various figures. In particular, common structural and / or functional features in various embodiments may have the same reference numerals and may be configured with the same structure, dimensions, and material properties.

[0037] For the sake of clarity, only those operations and elements useful for understanding the embodiments described herein are described and described in detail. In particular, the applications and systems in which the electronic components can be provided are not described in detail, and the described embodiments and variants are compatible with common applications and systems including one or more electronic components, and appropriate adjustments may be required, which are within the capabilities of those skilled in the art based on reading this specification.

[0038] Unless otherwise specified, when two elements are referred to as being connected together, this means a direct connection without any intermediate elements except conductors, and when two elements are referred to as being coupled together, this means the two elements may be connected or they may be coupled through one or more other elements.

[0039] In the following disclosure, unless otherwise stated, when referring to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or referring to relative position qualifiers, such as the terms "above", "below", "high", "low", etc., or referring to direction qualifiers, such as "horizontal", "vertical", etc., reference is made to the direction shown in the figure.

[0040] Unless otherwise indicated, the expressions "about", "approximately", "substantially" and "approximately" mean within 10%, preferably within 5%.

[0041] In the following description, the qualifiers "insulating" and "conductive" refer to electrical insulation and electrical conduction, respectively, unless otherwise specified.

[0042] Figure 1A , Figure 1B , Figure 1C , Figure 1D and Figure 1E 1 is a schematic partial cross-sectional view illustrating successive steps in a process of manufacturing electronic assembly 100 according to one embodiment.

[0043] Figure 1A Specifically, the mask 101 is disposed on the surface 103T of the substrate 103 (on the Figure 1A The step of placing the substrate 103 on and in contact with the upper surface of the substrate 103 in an orientation completes the structure obtained.

[0044] In the example shown, the mask 101 forms a discontinuous layer extending laterally above and in contact with the surface 103T of the substrate 103. In this example, the mask 101 includes separate portions that laterally define the aperture. For example, the mask 101 is a screen printing mask. As an example, the mask 101 is made of an insulating material, such as a resin.

[0045] The substrate 103 is, for example, a wafer or a piece of a wafer made of a semiconductor material such as silicon or germanium nitride (GaN). Figure 1A Although not described in detail, the substrate 103 includes, for example, at least one unitary electronic component, for example, at least one unitary power electronic component. For example, each unitary electronic component includes at least one element selected from the following: a diode, a thyristor, a thyristor, a transistor, a resistive, capacitive or inductive load, etc.

[0046] In the example shown, the contact forming element 105 is located on and in contact with a portion of the face 103T of the substrate 103 that is not coated with the mask 101. For example, the contact forming element 105 is connected to a conduction and / or control electrode of a unit electronic component formed in the substrate 103. As an example, the contact forming element 105 is a conductive pad, such as a pad made of metal (e.g., copper or a metal alloy). For example, the mask 101 is aligned with the position of the contact forming element 105 on the face 103T of the substrate 103. Figure 1A In the example shown, two contact-making elements 105 are located in each opening of the mask 101. However, this example is not limiting, since the number of contact-making elements 105 located in each opening of the mask 101 may alternatively be different from two.

[0047] Figure 1B Specifically, the step of forming the conductive region 107 in the opening of the mask 101 is shown. Figure 1A The structure obtained by .

[0048] In the example shown, the conductive areas 107 fill the openings in the mask 101, i.e. completely fill all free spaces extending laterally between the portions of the mask 101. In this example, the conductive areas 107 are delimited by the mask 101, with the flanks of each conductive area 107 being covered by portions of the mask 101. In the example shown, the conductive areas 107 coat the contact-forming elements 105 and the portions of the surface 103T of the substrate 103 that are not coated by the mask 101 or the contact-forming elements 105. In the example shown, each conductive area 107 coats two contact-forming elements 105. In the example shown, the conductive areas 107 are in contact with the face of the mask 101 opposite to the substrate 103 (at Figure 1B In the direction of the mask 101, the upper surface of the mask 101 is flush.

[0049] The conductive area 107 is, for example, made of a solder soldering material, such as solder paste. At this stage of the process, the material of the conductive area 107 comprises, for example, a metal alloy, for example in the form of metal alloy balls or microspheres dispersed in a viscous or pasty material.

[0050] In one embodiment, the metal alloy contained in the conductive region 107 mainly includes bismuth (Bi). More precisely, for example, the bismuth content of the alloy exceeds 80%, for example, about 90%. For example, the alloy also includes at least one additional element selected from silver (Ag), nickel (Ni) and tin (Sn). In this case, for example, the content of each additional element of the alloy is less than 10%, for example, about 5%. As an example, the metal alloy of the conductive region 107 has a bismuth content equal to about 90%, a silver content equal to about 5% and a nickel content equal to about 5%. For example, the melting point of the alloy is between 270 and 290° C. Note that the percentages shown here for the alloy composition correspond to mass content or mass percentage.

[0051] Figure 1C Specifically, after the steps of removing the mask 101, reflowing the conductive region 107, and forming the groove 109 in the conductive region 107 and the substrate 103, the Figure 1B The structure obtained by .

[0052] exist Figure 1C In the example shown, the mask 101 is completely removed.

[0053] In the example shown, the conductive areas 107 are subjected to a reflow phenomenon, for example by performing a heating operation exposing the structure to a temperature above the melting point of the metal alloy contained in the conductive areas 107. If the alloy is dispersed in the form of balls or microspheres in a flux, this operation melts the balls or microspheres and removes the flux. At the end of this operation, each conductive area 107 is substantially made of the metal alloy. In the example shown, the conductive areas 107 have curved or rounded sides after reflow. As an example, the sides of the conductive areas 107 have a curvature that depends on the surface tension of the metal alloy in the liquid state.

[0054] In the example shown, the groove 109 is substantially aligned with the center of the region 107. Figure 1C In the orientation shown, each trench 109 extends vertically from the top surface of one of the conductive regions 107, through that region 107, and into the thickness of the substrate 103. In the example shown, the trenches 109 are located on a surface 103B of the substrate 103 opposite to the surface 103T (at Figure 1C 103T side of the substrate 103 is not open. For example, each groove 109 is laterally inserted between two contact-forming elements 105 that were initially coated by the same area 107. As an example, the grooves 109 are formed on the side of the face 103T of the substrate 103 by cutting, for example by sawing.

[0055] In the example shown, a unit electronic component formed in the substrate 103 and intended to form part of a single electronic component 100 is laterally delimited by grooves 109. When viewed from above, the grooves 109 are, for example, in the form of a grid, wherein each unit cell corresponds to a future electronic component 100. In the example shown, each contact-forming element 105 is coated with a portion of one of the conductive areas 107, which is separate from the portions of the conductive areas 107 that coat the other contact-forming elements 105. Figure 1C In the example shown, each future electronic component 100 comprises two contact-making elements 105 , each coated with two separate electrically conductive area portions 107 .

[0056] Figure 1D Specifically, the insulating layer 111 is deposited on the 103T side of the substrate 103, and the structure is thinned on the 103T and 103B sides of the substrate 103. Figure 1C The structure obtained is shown.

[0057] In the example shown, the insulating layer 111 fills (ie completely fills) the trenches 109 and all free spaces extending laterally between the regions 107. By way of example, the insulating layer 111 is made of a resin, such as a molding resin designed to form an encapsulation around each future electronic component 100.

[0058] In the embodiment shown, the structure is thinned on the 103T side of the substrate 103, for example by grinding, to reduce the thickness of the region 107 and the insulating layer 111. In the example shown, the insulating layer 111 is connected to the side of the region 107 opposite to the substrate 103 (at Figure 1D orientation, the top surface of region 107 is flush.

[0059] Furthermore, the structure is thinned on the face 103B side of the substrate 103, for example by grinding, to expose the portion of the insulating layer 111 filling the bottom of the trench 109. Thus, the portion of the insulating layer 111 located within the trench 109 is flush with the surface 103B of the substrate 103. As an example, before the thinning of the structure on the 103B side is performed, the structure is temporarily transferred to a support substrate or handle on the 103T side of the substrate 103, and then the support substrate is removed after the thinning.

[0060] Figure 1E Specifically shown is a step in which a further insulating layer 113 is deposited on the 103B side of the substrate 103 and in which the substrate 103 is cut through its entire thickness to separate or singulate the electronic components 100. Figure 1D The structure obtained is shown.

[0061] In the example shown, the insulating layer 113 is located on and in contact with the face 103B of the substrate 103, and on and in contact with the portion of the insulating layer 111 flush with the face 103B of the substrate 103. The layer 113 is for example made of a resin, for example a molding resin intended to form part of the package of the electronic component 100. As an example, the insulating layers 111 and 113 are made of the same material.

[0062] In the example shown, the structure includes a conductive region 107 on the side opposite to the substrate 103 (at Figure 1E oriented upward, the top surface of the conductive region 107) vertically extends through the thickness of the conductive region 107. In an embodiment, the height or depth of the trench 115 is less than the height or thickness of the conductive region 107. When viewed from above, the trenches 115 and 117 surround each electronic component 100.

[0063] In the example shown, the structure further includes trenches 117, the width of which is smaller than the width of trenches 115. In the embodiment shown, each trench 117 extends vertically from the bottom of one of the trenches 115 through the conductive region 107, the substrate 103, and the insulating layer 113. Thus, the trenches 117 have an open end on the 103B side of the substrate 103. In the example shown, the width of the trenches 117 is strictly smaller than the width of the portion of the insulating layer 111 located within the trenches 109.

[0064] For example, trench 115 is formed before trench 117. For example, trenches 115 and 117 are formed by sawing.

[0065] In the example shown, the trenches 117 define a plurality of portions of the substrate 103 , each portion forming, for example, a portion of an integrated circuit chip 119 (or electronic chip) of one of the electronic assemblies 100 .

[0066] Figure 2 is a partial schematic cross-sectional view of an electronic device 200 including the electronic assembly 100 according to one embodiment.

[0067] In the example shown, the electronic device 200 comprises a support and interconnection substrate 203, such as a printed circuit board. In the embodiment shown, the contact forming element 205 is located on one face (at the Figure 2 The contact-forming element 205 is disposed on and in contact with the top surface of the support and interconnect substrate 203 in an orientation. For example, the contact-forming element 205 is connected to a conductive track formed on the substrate 203 and / or to a conductive via formed in the thickness of the substrate 203. As an example, the contact-forming element 205 is a conductive pad, such as a pad made of metal (e.g., copper or a metal alloy).

[0068] In the example shown, the electronic component 100 is attached to the support and interconnection substrate 203 by means of conductive areas 207 interposed between the component 100 and the substrate 203. More specifically, in this example, each conductive area 207 is interposed between one of the conductive areas 107 of the electronic component 100 and one of the contact-forming elements 205 of the support and interconnection substrate 203. Thus, each contact-forming element 205 of the support and interconnection substrate 203 is connected to one of the contact-forming elements 105 of the electronic component 100 by means of one of the conductive areas 207 and one of the conductive areas 107.

[0069] Conductive region 207 is made of a metal alloy, for example a metal alloy having a melting point strictly lower than the melting point of the metal alloy of conductive region 107. As an example, conductive region 207 is made of a lead-free alloy, for example an alloy of tin, silver and copper (Sn-Ag-Cu alloy), also abbreviated SAC.

[0070] In the embodiment shown, the conductive region 207 coats the face of the conductive region 107 that is located on the side of the supporting and interconnecting substrate 203 (at Figure 2 In addition, in the present embodiment, the conductive region 207 coats a portion of the side surface of the conductive region 107, that is, wets the side surface of the conductive region 107.

[0071] Figure 2 An example is shown in which the electronic device 200 includes a single electronic component 100. However, this example is not limiting, as in some embodiments the electronic device 200 includes any number of electronic components of the component 100 type. As an example, the electronic device 200 is integrated into a motor vehicle, and the electronic component 100 implements a protection function such as preventing electrostatic discharge to which the electronic device 200 may be exposed.

[0072] An advantage of the electronic assembly 100 is that the presence of the conductive area 107 with a high bismuth content enables wettable flanks to be obtained. This makes it easier to check the solder connection of the assembly 100 to the supporting and interconnection substrate 203. Another advantage of using a conductive area 107 made of a metal alloy with a high bismuth content is that it avoids problems of unintentional bridging or interconnections between adjacent integrated circuit chips during a reflow step of the material of the conductive area 107 before a dicing step aimed at singulating the integrated circuit chips. This is in particular due to the fact that the metal alloy with a high bismuth content has a higher surface tension in the liquid state than the alloys used, in particular the SAC alloys.

[0073] Furthermore, the high-bismuth alloy has the advantage that it can be used to replace expensive alloys (e.g., gold-tin alloys) for producing solder joints in materials having a melting point strictly higher than that of the SAC alloy. In this case, for example, the high-bismuth alloy at least partially coats the bottom surface of an integrated circuit chip superimposed on another integrated circuit chip, such as a front bonding Figure 1E Chip 119 is depicted as an integrated circuit chip of the type described herein.

[0074] A number of embodiments and variations have been described. Those skilled in the art will appreciate that certain features of these embodiments and variations may be combined, and those skilled in the art will readily conceive of other variations.

[0075] Finally, based on the functional description provided herein, the actual implementation of the embodiments and variants described herein is within the capabilities of a person skilled in the art. In particular, the bismuth content in the metal alloy of the conductive region 107 can be adjusted according to the application, for example, to obtain a compromise between the increase in the surface tension of the alloy in the liquid state obtained by increasing the bismuth content in the alloy and the increase in the wettability of the side of the electronic component 100 obtained by reducing the bismuth content in the alloy.

[0076] An electronic component (100) comprises: an integrated circuit chip (119); a package (111, 113) surrounding the integrated circuit chip; and a first conductive region (107) at least partially coating one side of the integrated circuit chip, the first conductive region comprising an alloy primarily containing bismuth.

[0077] In one embodiment, the alloy has a bismuth content exceeding 80%, preferably equal to about 90%.

[0078] In one embodiment, the alloy further includes at least one additional element selected from silver, nickel and tin.

[0079] In one embodiment, said alloy has a content of said at least one additional element less than 10%, preferably equal to about 5%.

[0080] In one embodiment, the alloy has: a bismuth content equal to about 90%; a silver content equal to about 5%; a nickel content equal to about 5%

[0081] In one embodiment, the alloy has a melting point between 270 and 290°C.

[0082] An electronic device (200) comprises: a supporting and interconnecting substrate (203); at least one contact-forming element (205) located on one side of the supporting and interconnecting substrate; at least one electronic component (100); and at least one second conductive region (207) inserted between the at least one contact-forming element and the at least one first conductive region (107) of the electronic component.

[0083] In one embodiment, the second conductive region (207) covers a side surface of the electronic component (100).

[0084] In one embodiment, the second conductive region (207) is made of an alloy of tin, silver and copper.

[0085] A motor vehicle comprises at least one device (200).

[0086] A method of manufacturing an electronic component (100) comprising an integrated circuit chip (119) and a package (111, 113) surrounding the integrated circuit chip, the method comprising the step of at least partially coating a face of the integrated circuit chip with a first conductive region (107) comprising an alloy containing mainly bismuth.

[0087] These and other changes can be made to the embodiments in light of the above detailed description. In general, in the following claims, the terms used should not be interpreted to limit the claims to the specific embodiments disclosed in the specification and claims, but should be interpreted to include all possible embodiments and the full range of equivalents to which these claims are entitled. Therefore, the claims are not limited by this disclosure.

Claims

1. An electronic device, comprising: Integrated circuit chips; The packaging surrounding the integrated circuit chip; and at least a first conductive region at least partially coating one side of the integrated circuit chip, the first conductive region comprising an alloy having at least 50% bismuth, Therein, each first electrically conductive region is intended to be coated by a second electrically conductive region of a metal alloy.

2. The device according to claim 1, wherein the bismuth content of the alloy exceeds 80%.

3. The device according to claim 2, wherein the bismuth content of the alloy is approximately equal to 90%.

4. The device according to claim 1, wherein the alloy further includes at least one additional element selected from silver, nickel and tin.

5. The device according to claim 4, wherein the content of the at least one additional element of the alloy is less than 10%.

6. Device according to claim 5, wherein said alloy has a content of said at least one additional element equal to about 5%.

7. The device of claim 1, wherein the alloy has: Bismuth content equal to about 90%; A silver content equal to about 5%; and This equates to a nickel content of approximately 5%.

8. The device of claim 1, wherein the melting point of the alloy is between 270 and 290°C.

9. The device according to claim 1, comprising: support and interconnect substrates; at least one contact-forming element located on one face of said support and interconnect substrate; and At least one second conductive region is interposed between the at least one contact-forming element and the at least one first conductive region. 10 . The device of claim 9 , wherein the second conductive region covers a side surface of the first conductive region.

11. The device of claim 9, wherein the second conductive region is made of an alloy of tin, silver and copper.

12. The device according to claim 1, wherein: The melting point of the metal alloy of the second conductive region is strictly lower than the melting point of the metal alloy of the first conductive region.

13. A method comprising: The package surrounds the integrated circuit chip, including: at least partially coating the front side of the integrated circuit chip with a first conductive region, the first conductive region comprising an alloy having at least 50% bismuth; and An encapsulation layer is formed on the sidewalls and backside of the integrated circuit chip.

14. The method of claim 13, wherein at least partially coating the front side comprises: A first portion of the alloy is deposited on a first contact-forming element on the front side, and a second portion of the alloy is deposited on a second contact-forming element on the front side, the first portion and the second portion being separated by a gap.

15. The method of claim 14, comprising filling the void with the encapsulation layer.

16. The method according to claim 17, comprising: forming a second conductive region on the substrate; and The package is positioned on the second conductive region, the second conductive region being positioned on a sidewall of the first conductive region. The method of claim 16 , wherein the second conductive region is made of an alloy of tin, silver and copper.

18. The method of claim 15, comprising reflowing the first conductive region before filling the gap with the encapsulation layer.

19. A motor vehicle comprising: Electronic device, including: substrate; and A package on a substrate, the package comprising: Integrated circuit chips; An encapsulation layer on the first side and sidewalls of the integrated circuit chip; and A first conductive region at least partially coats the second side of the integrated circuit chip, the first conductive region comprising an alloy having at least 50% bismuth.

20. The motor vehicle of claim 19, wherein the electronic device includes a second conductive region located on the substrate between the substrate and the package, the second conductive region being located on a sidewall of the first conductive region.

21. The motor vehicle of claim 20, wherein the second conductive region is made of an alloy of tin, silver and copper.

Images