Method for manufacturing electronic component

Abstract

The invention relates to a manufacturing method of an electronic component. The present specification provides a method of manufacturing an electronic component having wettable flanks. In an example, a method of manufacturing an electronic component is for manufacturing an electronic component having wettable flanks from a substrate. The first surface of the substrate is covered by the connection terminal. A chip is formed in the substrate. The method includes welding a metal grid including connection pads connected to each other by rods to connection terminals; forming an insulating resin layer on the substrate, wherein the insulating resin layer surrounds the connection pad; separating the chips from each other; and obtaining an electronic component having a wettable flank, wherein the lateral portion of the connection pad and a portion of the insulating resin layer form the wettable flank of the electronic component.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of French Patent Application No. 2400539, filed on January 19, 2024, entitled "Procédé de fabrication de composants électroniques", which is hereby incorporated by reference in its entirety to the maximum extent permitted by law. Technical field

[0003] This specification relates to the manufacture of electronic components. More particularly, it applies to the manufacture of so - called surface - mount components, i.e., components having one or more connection metallizations on at least one face, which connection metallizations are designed to be soldered to corresponding connection pads on an external device such as a printed circuit board or another component. Background art

[0004] In some applications, surface - mount components are required in which the connection metallizations designed to be soldered to an external device extend all the way to the component flanks. These are called "wettable flank" components. When the component is installed in its environment (e.g., on a printed circuit board), the connection metallizations (also called electrical contacts) are soldered or brazed to the corresponding metal tracks or elements on the PCB side. Then, some of the solder material rises up the sides of the component, enabling a visual inspection of the connection quality.

[0005] This need exists, for example, in the automotive or medical fields, and more generally in all fields where the reliability of the electrical connection must be ensured once the circuit has been installed in its environment. Summary of the invention

[0006] There is a need to improve at least some aspects of the known processes for manufacturing electronic components with wettable flanks.

[0007] This is achieved by a method for manufacturing an electronic component with wettable flanks from a substrate whose first face is covered with connection terminals and in which a chip is formed, the method comprising:

[0008] - A first step in which a metal grid is soldered to the connection terminals, the metal grid comprising connection pads interconnected by bars,

[0009] - A second step in which an insulating resin layer is formed on the substrate, the insulating resin layer surrounding the connection pads,

[0010] - A third step in which the chips are separated from each other, thereby obtaining an electronic component with wettable flanks, the lateral portions of the connection pads and a part of the insulating resin layer forming the flanks of the component.

[0011] According to an embodiment, in a first step, the metal grid is welded to the connection terminal by means of a brazing layer deposited by a printing technique, preferably by screen printing.

[0012] According to an embodiment, the screen-printed brazing layer is made of Sn or a tin alloy such as SnAg or SnAgCu. The screen-printed brazing layer can mechanically establish an electrical connection between two or more parts.

[0013] According to an embodiment, the process includes: forming trenches in the substrate between the chips before a second step; and wherein, in the second step, the trench is filled with an insulating resin layer.

[0014] According to an embodiment, after the second step, the insulating resin layer is thinned.

[0015] According to an embodiment, the method includes the following steps:

[0016] - Performing a first step,

[0017] - Performing a second step,

[0018] - Performing a third step.

[0019] According to an embodiment, the method includes the following steps:

[0020] - Performing a first step,

[0021] - Forming trenches in the substrate,

[0022] - Performing a second step,

[0023] - Removing the portion of the resin layer that is located between the connection pads and above the trenches,

[0024] - Performing a third step by thinning the second side of the substrate all the way to the trenches,

[0025] - Applying an additional layer of resin to the second side of the substrate,

[0026] - Cutting the resin into the trenches.

[0027] According to an embodiment, the method includes the following steps:

[0028] - Performing a first step,

[0029] - Fixing the component obtained in the first step to a support including an adhesive layer by bonding the metal grid to the adhesive layer,

[0030] - Performing a third step,

[0031] - Perform the second step,

[0032] - Cut the resin in the trench.

[0033] According to an embodiment, between the first step and the third step, the substrate is thinned from the second side, and an additional resin layer is deposited on the second side of the substrate.

[0034] This is also achieved by an electronic component having wettable flanks, which includes a chip protected by a housing, the housing includes a first main surface, flanks, and a second main surface, connection pads are welded to connection terminals on the chip, and an insulating resin layer partially surrounds the connection pads, and the lateral portions of the connection pads and a part of the insulating resin layer form the flanks of the housing.

[0035] According to an embodiment, the connection pads are welded to the connection terminals by means of a brazing layer made of Sn or a tin alloy (such as SnAg or SnAgCu), and the connection pads are made of copper, which may be coated with a metal layer. In various alternative embodiments, the electrical connection between the parts can be established by soldering, sintering, US welding, laser welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The foregoing features and advantages, as well as other features and advantages, will be described in detail with reference to the accompanying drawings in the description of specific embodiments given in an illustrative but not restrictive manner, in which:

[0037] Figure 1A 、 Figure 1B and Figure 1C show a schematic cross-section of an electronic component having wettable flanks according to various specific embodiments;

[0038] Figure 2A 、 Figure 2B 、 Figure 2C 、 Figure 2D and Figure 2E are cross-sectional views illustrating steps in the process of manufacturing an electronic component having wettable flanks according to a specific embodiment;

[0039] Figure 3A 、 Figure 3B 、 Figure 3C 、 Figure 3D 、 Figure 3E 、 Figure 3F 、 Figure 3G and Figure 3H are cross-sectional views illustrating steps in the process of manufacturing an electronic component having wettable flanks according to another specific embodiment;

[0040] Figure 4A 、Figure 4B , Figure 4C , Figure 4D , Figure 4E and Figure 4F are cross-sectional views showing steps in a process for manufacturing an electronic component having wettable flanks according to another specific embodiment; and

[0041] Figure 5 shows Figure 4C a variant of DETAILED DESCRIPTION

[0042] Identical features in the respective figures have been denoted by the same reference numerals. In particular, structural and / or functional features common among the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.

[0043] For clarity, only the operations and elements useful for understanding the embodiments described herein have been illustrated and described in detail.

[0044] Unless otherwise specified, when referring to two elements connected together, this means a direct connection without any intermediate element other than a conductor, and when referring to two elements coupled together, this means that the two elements may be connected or they may be coupled via one or more other elements.

[0045] In the following disclosure, unless otherwise specified, when referring to absolute position determiners such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position determiners such as the terms "above", "below", "higher", "lower", etc., or orientation determiners such as "horizontal", "vertical", etc., they refer to the orientation shown in the respective figures.

[0046] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "about" mean within 10%, preferably within 5%.

[0047] The electronic component is used in a wide range of industrial fields, particularly in the automotive and medical fields.

[0048] Figure 1A , Figure 1B and Figure 1C show schematic partial cross-sectional views of different versions of the electronic component 100.

[0049] The electronic component 100 includes an electronic chip 103 and a housing 109. In one example, the chip 103 is formed from a semiconductor substrate such as silicon or SiC. Alternatively, the substrate may be glass or sapphire.

[0050] The chip includes a front side 105 (also referred to as the first side or the front side), a rear side 104 (also referred to as the second side or the back side), and side walls 106 (also referred to as the side surfaces). The lower side 104 is opposite to the upper side 105.

[0051] One or more connection terminals 107 (also referred to as electrical contacts) are formed on the top surface 105 of the microchip 103, enabling it to be connected to other components (microchips or electronic devices).

[0052] The electrical connection terminals 107 are also referred to as "UBM" (under bump metallization). The electrical connection terminals 107 are made of a conductive material that is specifically designed to receive connection posts 117, especially a material that is designed to adhere well to the posts 117. The electrical connection terminals 107 include at least one of the following elements: gold, titanium, nickel, copper, copper-silver, tin, or tungsten. Preferably, they include gold or copper. The connection terminals 107 and the posts 117 can be plated.

[0053] The electrical connection terminals 107 are, for example, 10 to 50 μm, or even 10 to 30 μm, away from the chip side walls. The electrical connection terminals 107 can be located on the top surface 105 of the chip 103 or flush with the top surface (i.e., at the same level as the top surface 105 of the chip 103).

[0054] The chip 103 can include one or more discrete components. The one or more discrete components are, for example, selected from transistors, diodes, thyristors, triacs, filters, etc. The chip 103 can include one or more electronic circuits. The chip 103 can be used to implement a variety of electronic functions.

[0055] The component 100 is a so-called integrated component.

[0056] The chip 103 is protected by a housing 109. More specifically, the housing 109 at least covers the top surface 105. It can also cover the side surfaces 106 of the chip 103 and / or the rear side 106 of the chip 103.

[0057] The housing 109 is at least partially made of an electrically insulating material.

[0058] To connect the component 100 to other electronic components and / or circuits, the housing 109 also includes connection pads 117 (also referred to as housing contacts or contact caps). The connection pads 117 are located on the top surface 105 of the chip 103. Each connection pad 117 is connected to a connection terminal 107 on the chip 103.

[0059] The connection posts 117 are made of a conductive and "wettable" and / or solderable material (i.e., a material that can be soldered with solder or mechanically attached in other ways (e.g., conductive bonding, sintering, or welding)).

[0060] The connection post 117 is preferably made of one alloy among copper, tin or their alloys (such as SnAgCu or SnAg), or made of other materials with a higher melting point. Copper can be coated with an oxidation protection layer, such as a tin layer or a nickel layer, by means of Sn plating or Ni plating.

[0061] The electrical connection terminals 107 of the chip 103 and the connection posts 117 are located in the openings in the insulating resin layer 121 covering the chip 103. The connection pads 117 include a first part 117A welded to the connection terminals 107 and a second part, namely the so-called lateral part 117B.

[0062] The lateral part 117B of the connection post 117 forms part of the flank 119 of the component 100, and the first part 117A of the connection post 117 extends on the first main surface 115 of the component 100.

[0063] The component 100 is a wettable flank component, that is, at least a part of its flank is formed by a layer of wettable and solderable material (i.e., a material on which soldering can be performed). The other parts of the wettable flank are made of insulating resin. The wettable material layer is formed by the lateral part 117B of the connection post 117.

[0064] The wettable material part and the resin layer can be aligned, at the same level ( Figure 1A 、 1C ), or offset from each other ( Figure 1B ).

[0065] The first part 117A and the second part 117B of the connection post 117 can be made of the same material or different materials. These parts 117A and 117B are preferably made of the same material. Preferably, the first part 117A and the second part 117B of the connection post 117 are made of copper.

[0066] Now we will refer to Figures 2A to 2E 、 Figures 3A to 3H and Figures 4A to 4F to describe the manufacturing process of such a component 100 in more detail.

[0067] The process includes the following steps:

[0068] a) Providing a substrate 301 and providing a grid 116 ( Figure 2B 、 3B ), the first surface 305 of the substrate 301 is covered by the connection terminals 107 and a chip is formed in the substrate 301 ( Figure 2A 、 Figure 3A 、 Figure 4A ),

[0069] b) Welding the grid to the connection terminals 107 using the solderable material layer 105 (Figure 2C , Figure 3C , Figure 4B ),

[0070] c) Deposit an insulating resin layer 121 on the substrate 301, the insulating resin layer 121 surrounding the connection pads 117 and filling the spaces between the respective grid elements ( Figure 2D , Figure 3D , Figure 4D ),

[0071] d) Separate the chips 103 from each other ( Figure 2E , Figure 3F , Figure 4C ).

[0072] Steps a), b), c) and d) may be performed in the order described above, or may be performed in the following order: a), b), d), c).

[0073] In step a), the fabrication of the (one or more) discrete components and / or (one or more) integrated circuits of the component 100 is completed. The component 100 is formed from a single substrate 301 and has not yet been individualized. The substrate 301 includes a first face 305 (top or front face) and a second face 303 (or back face).

[0074] The substrate 301 is, for example, a semiconductor substrate such as silicon. It may also be SiC.

[0075] The thickness of the substrate 301 is between 300 and 900 μm, for example about 725 μm thick.

[0076] In addition, the electrical connection terminals 107 described with respect to FIG. 1 have been formed on the upper face 305 of the substrate 301 ( Figure 2A , 3A , 4A).

[0077] The grid is composed of connection pads 117 and bars 118 that connect the respective pads 117 to each other. The bars 118 form the rows and columns of the grid 116. The pads 117 are located at the intersections of the rows and columns. The pad 117 includes a first portion 117A that will be soldered to the connection terminal 107 and a second portion 117B that will serve as a wettable material on the side 119 of the component.

[0078] The connection pads 117 are linked together to form a network (grid) that enables these pads 117 to be deposited simultaneously over the entire substrate. A single step is required to position all the pads 117: a significant time saving is achieved compared to positioning the pads 117 one by one.

[0079] Depending on the size of the substrate 301 and the size of the grid 116, one or several grids can be soldered to the same substrate 301.

[0080] In step b), the connection pads 117 are soldered to the connection terminals 107.

[0081] The brazing material is pre-deposited on the connection terminals 107. It can be deposited by printing techniques (preferably screen printing or other techniques as described herein). Any additional deposition technique can be used. The brazing material can be Sn, or it can be a tin alloy (such as SnAgCu or SnAg), or other alloys with higher melting points.

[0082] In step c), an insulating resin layer 121 is deposited on the first side 305 of the substrate 301. This can be deposited by molding.

[0083] In particular, the insulating resin layer 121 is deposited on the first side 305 of the substrate 301 and in the grid spaces. In this way, the connection pads 117 are arranged within the resin. The insulating resin layer 121 forms part of the housing 109 of the component 100 and thus protects the top surface of the component 100.

[0084] The resin is an electrically insulating resin. More particularly, the resin includes at least one base material, and electrically insulating particles are added to the base material. The base material is selected from the group including the following: epoxy-type resins, phenolic-type resins, acrylic-type resins. Preferably, the resin is an epoxy-type resin. The particles are, for example, oxide particles, particularly alumina or silica particles.

[0085] The resin is cured, for example, under ultraviolet (UV) light or by thermal activation. Annealing can be performed after step c).

[0086] The step d) of separating the chips 103 can be performed by cutting the substrate 301 between the chips 103 ( Figure 2E and Figure 4C ).

[0087] Alternatively, step d) can be performed by forming trenches 311 between the chips 103 and then thinning the substrate until the trenches 311 ( Figure 3F ).

[0088] This process can be implemented in a variety of different ways.

[0089] According to Figures 2A to 2E the first embodiment shown in

[0090] - Implementing the above steps a), b) and c) ( Figures 2A to 2D ).

[0091] - Cut the substrate 301 to separate the individual components 100 ( Figure 2E ).

[0092] According to this first embodiment, one or more of the following steps may also be performed:

[0093] - If the resin covers the grid 116, then thin from the front side to remove the part of the insulating resin 121 that covers the grid 116 (especially the part that covers the connection pad 117),

[0094] - Thin the back side 303 of the substrate 301,

[0095] - Deposit an insulating resin layer on the back side of the substrate 301 to form the back of the housing 109 for the component 100 and / or deposit an insulating resin layer on the side wall of the substrate 301.

[0096] According to Figures 3A to 3H In the second embodiment shown in, the process includes the following steps:

[0097] - Implement step a) ( Figure 3A and 3B ), in which the substrate supplied in step a) includes trenches 311 between the chips,

[0098] - Implement step b) ( Figure 3C ),

[0099] - Implement step c) ( Figure 3D ),

[0100] - The step of thinning the resin on the front side because the resin covers the grid 116 ( Figure 3E ),

[0101] - The step of thinning the substrate 301 on the back side and depositing a resin layer to cover the back side 303 of the substrate 301 ( Figure 3E ); advantageously, the thinning step is performed until the trenches 311 are reached, thus enabling the easy separation of the individual components 100 in a later stage,

[0102] - Remove the part of the resin that is both above the trenches 311 and between the connection pads 117, whereby the lateral part 117B of the connection pad 117 is separated by the gap 312 ( Figure 3G ),

[0103] - Finally cut, so as to form additional trenches 313 between the components 100 ( Figure 3H ).

[0104] According to Figures 4A to 4F In the third embodiment shown in, the process includes the following steps:

[0105] - Perform step a) (Figure 4A ),

[0106] - Perform step b) ( Figure 4B ),

[0107] - Assemble the structure obtained in step b) on a support 400 including an adhesive part 401 and a support substrate 402, and cut the substrate 301 to separate the individual components ( Figure 4C ); The assembly is performed by bonding the grid 116 (in particular the connection pads 117) to the adhesive part 401,

[0108] - Perform step c) ( Figure 4D ),

[0109] - Thin the substrate 301 and the resin on the back side 303 and deposit an additional insulating resin layer 122 on the back side 303 of the substrate 301 ( Figure 4E ),

[0110] - Separate the individual components 100 by cutting through the resin between the components 100 via the trenches 311 ( Figure 4F ).

[0111] Then the support 400 can be removed. For example, UV treatment or heat treatment can weaken the adhesive properties of the layer 401, thus releasing the components 100.

[0112] Advantageously, the support substrate 402 is made of glass. The adhesive layer 401 is, for example, a UV - type adhesive.

[0113] In an alternative embodiment, the support includes an adhesive layer 401 and a handler 404 ( Figure 5 ).

[0114] In these different alternative embodiments, the front - side thinning step or the back - side thinning step can be performed by grinding.

[0115] The thinning step of the back side 303 results in a substrate 301 having its final thickness.

[0116] The step of forming the trenches 311 can be performed using a cutting device. The cutting device is, for example, a mechanical engraving tool such as a wafer saw, or a laser engraving tool. In a preferred embodiment, the cutting device is a laser. Furthermore, when the cutting device is a laser, the cutting technique used can be laser direct structuring (LDS) technology.

[0117] When performing singulation, the components 100 are individualized by cutting between the components 100 (e.g., at the trenches 311). Thus, the components 100 are separated from each other.

[0118] The additional insulating resin layer 122 is a layer of electrically insulating material, for example a resin of the same type as the resin layer 121. According to another example, the materials of the layers are different.

[0119] At the end of this process, the obtained components 100 are surface mount devices (SMDs) of the "flip chip" type, i.e., they can be attached to an external device, such as a printed circuit board or another component, through their top surface (i.e., the surface on which the contact pads 117 of the housing 109 are arranged).

[0120] To achieve this, a soldering material is positioned between the component 100 and the external device. During soldering, the soldering material rises up the side 119 of the component 100, thus allowing verification that the soldering has been correctly performed.

[0121] Once the circuit has been installed in its environment, such components 100 are particularly attractive for ensuring the reliability of the electrical connection.

[0122] Multiple embodiments and variants have been described. Those skilled in the art will understand that certain features of these embodiments can be combined, and other variants will readily occur to those skilled in the art.

[0123] Finally, based on the functional descriptions provided above, the actual implementation of the embodiments and variants described herein is within the capabilities of those skilled in the art.

Claims

1. A method for manufacturing an electronic component with wettable flanks from a substrate, wherein a first side of the substrate is covered with connection terminals and chips are formed in the substrate, the method comprising: Welding a metal grid including connection pads interconnected by bars to the connection terminals; Forming an insulating resin layer on the substrate, wherein the insulating resin layer surrounds the connection pads; Separating the chips from each other; and Obtaining an electronic component with wettable flanks, wherein lateral portions of the connection pads and a part of the insulating resin layer form the wettable flanks of the electronic component.

2. The method according to claim 1, wherein welding the metal grid to the connection terminals is effected by means of a brazing layer deposited by a printing technique.

3. The method according to claim 2, wherein the printing technique is used for a screen-printed brazing layer made of Sn or a tin alloy.

4. The method according to claim 1, further comprising: Forming trenches in the substrate between the chips before forming the insulating resin layer, and wherein, in forming the insulating resin layer, the insulating resin layer fills the trenches.

5. The method according to claim 1, wherein, Thinning the insulating resin layer after forming the insulating resin layer.

6. The method according to claim 1, further comprising: Forming trenches in the substrate before forming the insulating resin layer; Removing portions of the insulating resin layer that are both between the connection pads and above the trenches after forming the insulating resin layer; Separating the chips from each other by thinning a second side of the substrate all the way to the trenches; Applying an additional layer of resin to the second side of the substrate; And Cutting the resin into the trenches.

7. The method according to claim 1, wherein, Thinning the substrate from a second side between welding the metal grid and separating the chips, and depositing an additional resin layer on the second side of the substrate.

8. A method for manufacturing an electronic component with wettable flanks from a substrate, wherein a first side of the substrate is covered with connection terminals and chips are formed in the substrate, the method comprising: Welding a metal grid including connection pads interconnected by bars to the connection terminals to form an assembly; Fixing the assembly obtained by welding the metal grid to a support including the adhesive layer by bonding the metal grid to an adhesive layer; Separating the chips from each other; Forming an insulating resin layer on the substrate, wherein the insulating resin layer surrounds the connection pads; and Cutting the resin in one or more trenches.

9. An electronic component with wettable flanks, comprising chips protected by a housing, the housing including: A first main side; A plurality of wettable flanks; A second main side; A plurality of connection pads welded to connection terminals on the chips; And An insulating resin layer that partially surrounds the plurality of connection pads, with lateral portions of the connection pads and a part of the insulating resin layer forming the plurality of wettable flanks of the housing.

10. The electronic component according to claim 9, wherein the connection pads are welded to the connection terminals by means of a brazing layer of Sn or a tin alloy, and wherein the connection pads are made of copper.

Images