Electronic device and forming method thereof

Abstract

The invention provides an electronic device and a forming method thereof. The method comprises: providing a substrate having a front surface, wherein the substrate comprises at least one non-polar material; providing at least one electronic component having solder bumps mounted on a rear surface thereof, where the solder bumps are coated with a flux material, the flux material comprising at least one polar material, and the at least one electronic component comprising at least one non-polar material; placing the at least one electronic component onto the front surface of the substrate via the solder bump; and applying microwave radiation to the at least one electronic component to heat the solder bump by the flux material.

Description

Technical Field

[0001] The present application generally relates to semiconductor technology, and more particularly, to an electronic device and a method of forming the same. Background Art

[0002] The semiconductor industry has been facing complex integration challenges as consumers want their electronic devices to be smaller, faster, and more performant while packing an increasing number of functions into a single device. Typically, electronic components are mounted onto a substrate via solder bumps. The formation of solder bumps may involve a reflow soldering process, which enables an effective electrical connection between the substrate and the electronic components thereon. The reflow soldering process can heat the entire device by means of thermal convection, thereby causing the solder bumps to form therein. However, due to the different coefficients of thermal expansion (CTE) between different materials within the device, the heating process by convective heat transfer may cause warping problems, which may adversely affect device performance and subsequent manufacturing processes.

[0003] Therefore, there is a need for further improvement in methods for forming electronic devices. Summary of the Invention

[0004] One objective of the present application is to provide an improved method for forming an electronic device.

[0005] According to one aspect of the present application, there is provided an electronic device and a method of forming the same. The method includes: providing a substrate having a front surface, wherein the substrate includes at least one non-polar material; providing at least one electronic component having solder bumps mounted on its rear surface, wherein the solder bumps are coated with a flux material, the flux material includes at least one polar material, and the at least one electronic component includes at least one non-polar material; placing the at least one electronic component onto the front surface of the substrate via the solder bumps; and applying microwave radiation to the at least one electronic component to heat the solder bumps through the flux material.

[0006] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory, and do not limit the present invention. Additionally, the accompanying drawings incorporated in this specification and constituting a part of this specification illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. Brief Description of the Drawings

[0007] The accompanying drawings referred to herein form a part of this specification. The features shown in the drawings illustrate only some embodiments of the present application and not all embodiments of the present application, unless the specific implementation clearly indicates otherwise, and the readers of this specification should not make an opposite inference.

[0008] Figures 1A to 1F Shows the respective steps of a method for forming an electronic device according to a first embodiment of the present application.

[0009] Figure 2 Shows the step of microwave radiation in a method for forming an electronic device according to a second embodiment of the present application.

[0010] The same reference numerals will be used throughout the drawings to refer to the same or similar parts. Detailed Description

[0011] The following detailed description of exemplary embodiments of the present application refers to the accompanying drawings that form a part of the description. The drawings illustrate specific exemplary embodiments in which the present application may be practiced. The detailed description including the drawings describes these embodiments in sufficient detail to enable those skilled in the art to practice the present application. Those skilled in the art may further utilize other embodiments of the present application and make logical, mechanical, and other changes without departing from the spirit or scope of the present application. Therefore, the reader of the following detailed description should not interpret the description in a limiting sense, and only the appended claims define the scope of the embodiments of the present application.

[0012] In the present application, unless otherwise expressly stated, the use of the singular includes the plural form. In the present application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "comprising" is not restrictive. Further, unless otherwise expressly stated, terms such as "element" or "component" cover both elements and components that include one unit and elements and components that include more than one sub-unit. Additionally, the section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0013] As used herein, for ease of description, spatial relative terms such as "under", "below", "above", "over", "on", "upper", "lower", "left", "right", "vertical", "horizontal", "side", etc. may be used to describe the relationship of one element or feature to another element(s) or feature(s) as shown in the drawings. Except for the orientation depicted in the drawings, the spatial relative terms are intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptive words used herein may be interpreted accordingly. It should be understood that when an element is referred to as "connected to" or "coupled to" another element, the element may be directly connected to or coupled to the other element, or there may be intervening elements.

[0014] As mentioned above, electronic components are typically mounted onto a substrate via solder bumps. The formation of solder bumps may involve a reflow soldering process, which achieves an effective electrical connection between the substrate and the electronic components thereon. The reflow soldering process can heat the entire device by means of thermal convection, thereby causing the solder bumps to form therein. However, due to the differences in the coefficients of thermal expansion (CTEs) between different materials within the device, the heating process by convective heat transfer may cause warping problems, which may adversely affect device performance and subsequent manufacturing processes. To address this issue, a new method for forming an electronic device is provided. The new method applies microwave radiation to heat the solder bumps through the flux material, which reduces the warping problems of the electronic device, especially when the device is within a substrate strip before the singulation process. The method can be used to form electronic devices with smaller sizes and more complex structures, such as system-in-package (SIP) devices having various electronic components.

[0015] Figures 1A to 1F Illustrates the various steps of a method for forming an electronic device according to a first embodiment of the present application. Hereinafter, the method will be described in reference to Figures 1A to 1F in more detail.

[0016] As Figure 1A shown, the substrate 100 has embedded interconnects 101. The substrate 100 includes a front surface, which can serve as a platform for mounting electronic components. Multiple sets of conductive pads (not shown) may be formed on the front surface of the substrate 100 for the mounting of electronic components. It can be understood that the multiple sets of conductive pads may be exposed portions of the interconnects 101 formed within the substrate 100.

[0017] In Figure 1A the illustrated embodiment, the substrate 100 includes at least one non-polar material, such as silicon, and the at least one non-polar material is a major portion of the material of the substrate 100. It should be noted that the substrate 100 may also contain a small amount of polar material. For example, in this embodiment, the substrate 100 may contain more than 99 wt.% of non-polar material and less than 1 wt.% of polar material, which can help improve the structural and electrical properties of the substrate 100. In some other embodiments, the substrate 100 may contain less than 2 wt.%, 5 wt.%, or 10 wt.% of polar material.

[0018] As Figure 1BAs shown, at least one electronic component 110 is provided. In some embodiments, the electronic component 110 may include various types of electronic modules, such as semiconductor chips, resistors, capacitors, etc. In alternative embodiments, the at least one electronic component 110 may include a semiconductor package. For example, a semiconductor package may include a package substrate, at least one electronic module mounted on the package substrate, and a mold cap encapsulating the at least one electronic module. It can be understood that the electronic component 110 can be arranged and sized according to the actual requirements of the electronic device. In some embodiments, different types of electronic components 110 may be included in a single electronic device depending on the actual requirements. In addition, the at least one electronic component 110 includes at least one non-polar material. It can be understood that similar to Figure 1A the substrate 100 shown in, the electronic component 110 may contain a small amount of polar material, such as an encapsulant or adhesive within the electronic component 110. For example, the electronic component 110 may contain greater than 99 wt.%, 98 wt.%, 95 wt.%, or 90 wt.% of non-polar material, and correspondingly less than 1 wt.%, 2 wt.%, 5 wt.%, or 10 wt.% of polar material.

[0019] Next, a solder material is deposited on the rear surface of the electronic component 110 to form a plurality of solder bumps 111 on multiple sets of conductive pads. In some embodiments, the solder bumps 111 may include a metal material, a combination of multiple metal materials, or a combination of metal and non-metal materials. More specifically, the solder material may be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, or a combination thereof. In some embodiments, the solder bumps 111 may include metal powder. For example, the solder bumps 111 may be sintered metal powder. In some other embodiments, the solder bumps 111 may include metal powder and an adhesive material that glues the metal powder together. The adhesive material should be sticky enough to hold the metal powder together before, during, and after the heating process of the solder bumps 111. In other words, the adhesive material should not completely volatilize during the heating process of the solder bumps 111. In addition, the adhesive material may include a thermally conductive material that ensures effective convective heat transfer within the solder bumps 111 during the heating process. In some alternative embodiments, the adhesive material may include a polar material that can absorb microwave energy and thus can be specifically heated, thereby further promoting the heating process of the solder bumps 111 when the solder bumps 111 are subsequently exposed to microwave radiation.

[0020] Next, as Figure 1CAs shown, the flux material 112 is coated on the surface of the solder bump 111. The flux material 112 can assist in the subsequent heating process of the solder bump 111, thereby enabling a sufficient electrical connection between the substrate 100 and the at least one electronic component 110 through the solder bump 111. The flux material 112 contains a large amount of one or more polar materials that can be selectively heated when exposed to microwave radiation. In addition, in some embodiments, the flux material 112 contains one or more polar materials whose degree of polarization is higher than that of the solder bump 111. Therefore, when the flux material 112 and the solder bump 111 are exposed to microwave radiation together, the flux material 112 can be heated to a higher temperature compared to the solder bump 111, thus achieving sufficient convective heat transfer from the flux material 112 to the solder bump 111. In some embodiments, the flux material 112 may contain one or more materials selected from the following combinations: nonylphenol ethoxylate, glycerol monostearate, acid activator, water, and inorganic salts. In a preferred embodiment, the flux material 112 may contain nonylphenol ethoxylate between 40 wt.% and 70 wt.%, glycerol monostearate between 10 wt.% and 30 wt.%, acid activator between 3 wt.% and 10 wt.%, water between 3 wt.% and 10 wt.%, and inorganic salts between 4 wt.% and 15 wt.%.

[0021] In Figure 1C the embodiment shown, the flux material 112 is coated on the bottom surface of the solder bump 111. In some other embodiments, the flux material 112 may be coated on the entire spherical surface of the solder bump 111 exposed from the rear surface of the electronic component 110 to increase the contact area between the flux material 112 and the solder bump 111, thus enhancing the convective heat transfer from the flux material 112 to the solder bump 111.

[0022] Next, as Figure 1D shown, the at least one electronic component 110 is mounted on the front surface of the substrate 100 via the solder bump 111 coated with the flux material 112. The flux material 112 is between the bottom surface of the solder bump 111 and the top surface of the conductive pad. It can be understood that the flux material 112 may flow slightly towards the conductive pad due to surface tension, but most of the surface of the solder bump 111 can still be covered by the flux material 112.

[0023] Next, as Figure 1EAs shown, the microwave source is placed above the electronic component 110, and microwave radiation is applied from the microwave source to the electronic component 110, thereby heating the solder bumps 111 through the flux material 112. The electronic component 110, which usually contains non-polar materials, may not absorb or may hardly absorb microwave energy. Therefore, the microwave can penetrate the electronic component 110 and the solder bumps 111 and reach the flux material 112. In some other embodiments, the microwave source is placed at one or more sides of the electronic component 110. The microwave radiation can be applied to the solder bumps 111 and the flux material 112 from the side of the microwave source. Therefore, the microwave can interact more directly with the solder bumps 111 and the flux material 112 without having to pass through the electronic component 110 first, which can increase the energy absorption efficiency. It can also be understood that the position where the microwave source is placed can vary according to the actual layout of the electronic device. For example, one or more microwave sources can be tilted at 30 degrees, 45 degrees, 60 degrees or any other suitable degree with respect to the front surface of the substrate 100.

[0024] Still referring to Figure 1E , when the solder bumps 111 and the flux material 112 are simultaneously exposed to microwave radiation, the dipoles within the polar molecules of the flux material 112 are sensitively induced by the electric field of the microwave, and the dipoles can rotate under the action of the electric field to align themselves with the direction of the electric field. The electric field of the microwave changes periodically, which can cause the dipoles to rotate frequently. Therefore, when the dipoles rotate according to the direction of the electric field, they may collide with each other, generating heat energy and causing the flux material 112 to rise to a higher temperature, for example, a temperature higher than the melting temperature of the solder bumps 111. In addition, the solder bumps 111, especially the solder bumps 111 containing metal powder, can also absorb microwave energy to generate heat, which causes the solder bumps 111 to rise to a medium temperature. In the case where the flux material 112 is heated, a part of the heated flux material 112 can first volatilize, and the heat energy generated in the flux material 112 can be transferred to the solder bumps 111 in a convective manner, which can cause the solder bumps 111 to further heat up. Then, the temperature of the solder bumps 111 can rise above the melting temperature of the solder bumps 111, which causes the solder bumps 111 to start melting and reform during the reflow soldering process of the solder bumps 111. Finally, as Figure 1F shown, the flux material 112 can completely volatilize, so that the reflowed solder bumps 111 form an electrical connection between the interconnection line 101 and the electronic component 110. In some other embodiments, only a part of the flux material 112 volatilizes, and the finally remaining flux material 112 can be removed from the solder bumps 111. In some other embodiments, the finally remaining flux material 112 and the solder bumps 111 can be melted together to form an electrical connection between the interconnection line 101 and the electronic component 110.

[0025] During the microwave radiation process, the flux material 112 can be heated to a high temperature to provide sufficient heat to the flow solder bumps 111. At the same time, the flux material 112 should not be overheated to avoid complete volatilization of the flux material 112 before the solder bumps 111 fully undergo reflow soldering. In other words, the temperature of the flux material 112 should be controlled within an appropriate range. In some embodiments, when rosin is used as the flux material 112, especially for solder bumps that can melt above 230°C, the appropriate temperature range can be between 120°C and 350°C. In some other embodiments, for example, resin flux or other suitable polar flux materials can be used, and the appropriate temperature range can be between the melting temperature of the solder material and the temperature equal to or slightly higher than the vaporization temperature of the flux material 112, such as a temperature range from 10°C higher than the melting temperature of the solder material to 10°C higher than the vaporization temperature of the flux material 112, or to a temperature range 10°C lower than the vaporization temperature of the flux material 112. In some embodiments, microwave radiation can be applied intermittently to control the temperature of the heated flux material 112. For example, microwave radiation can be applied and maintained for a specific duration (e.g., 10 seconds to 2 minutes), and then the application of microwave radiation can be paused for another specific duration (e.g., 5 seconds to 30 seconds). In addition, depending on the reflow soldering process of the solder bumps 111, this cycle can be repeated several times. It can be understood that the specific duration can be from several seconds to several minutes, depending on the actual requirements of the heating process, such as the specific composition of the flux material 112 and / or the solder bumps 111, the number and size of the solder bumps 111, and / or the power of the microwave radiation, etc. In some other embodiments, temperature sensors such as infrared temperature sensors or infrared image arrays can be used to monitor the temperature of the flux material 112 or the solder bumps 111, and the real-time temperature measurement values can be provided to the controller of the microwave source to adjust the power and / or duration of the microwave radiation. In some preferred embodiments, the substrate 100 and the electronic components 110 mounted thereon can be placed in an atmosphere with a high ambient temperature to avoid excessive heat transfer from the flux material 112 and / or the solder bumps 111 to the substrate 100 and / or the electronic components 110 during the heating process due to a significant temperature difference between the substrate 100 and / or the electronic components 110 and the solder bumps 111 / flux material 112. For example, the ambient temperature can be 10°C to 150°C lower than the melting temperature of the solder bumps 111, or preferably 10°C to 50°C lower, or more preferably 10°C to 30°C lower.

[0026] In addition, in this embodiment, during the microwave radiation step, microwave radiation is applied at a variable frequency. By rapidly sweeping through a range of frequencies, as compared to fixed-frequency microwaves, the uniformity of the microwave energy can be increased. The microwave radiation can be applied at frequencies within the range between 1 GHz and 10 GHz. The microwave source power can be set in the range between 100 W and 2000 W. In other embodiments, the microwave radiation can be applied at frequencies higher than 10 GHz or at a microwave source power higher than 1000 W, which causes the solder bumps 111 and the flux material 112 to heat up faster. In addition, the microwave radiation needs to be sustained for a minimum duration (e.g., 1 minute) such that the solder bumps 111 undergo the reflow soldering process sufficiently and the flux material 112 is completely volatilized, thereby forming an effective electrical connection between the electronic component 110 and the interconnecting lines 101 within the substrate 100 and avoiding further cleaning of residual flux material after the reflow soldering process. It can also be appreciated that the frequency, power, and duration of the microwave radiation can be selected according to the actual requirements of the reflow soldering process of the solder bumps 111. At the same time, since the molecules in non-polar materials are insensitive to the electric field of microwaves, the substrate 100 and the electronic component 110 may not be heated by the microwave radiation or may be heated very little when they are exposed to the microwave field together with the solder bumps 111 and the flux material 112. In addition, the interconnecting lines 101 embedded within the substrate 100 and the metal layers that may be included within the electronic component 110 can reflect microwaves and generate very little heat energy. In this way, the solder bumps 111 and the flux material 112 are selectively heated by the microwave radiation. This heating mechanism can provide several advantages for the reflow soldering process of the solder bumps 111. First, this heating mechanism replaces the heating process that is conventionally applied to the entire electronic device, because the substrate 100 and the electronic component 110 are heated very little by the microwave radiation while the solder bumps 111 and the flux material 112 are selectively heated by the microwave radiation, thereby reducing the warping problems of the substrate 100 and the electronic component 110. Second, the microwaves can penetrate the flux material 112 and the solder bumps 111 to supply energy, and thus heat can be generated volumetrically throughout the solder bumps 111, which results in a more uniform heat distribution from the surface to the interior of the solder bumps 111. Third, the microwaves cause molecular rotation without breaking molecular bonds (due to the low energy of the photons), which can have very little impact on the internal structure of the components of the electronic device. Fourth, the microwave heating can be started and / or ended quickly, which can shorten the heating duration.

[0027] In an alternative embodiment, before applying microwave radiation, at least one additional electronic component may be provided, having additional solder bumps on a rear surface thereof, and the additional solder bumps are coated with an additional flux material, the additional flux material comprising at least one polar material, and the at least one additional electronic component comprising at least one non-polar material. Then, the at least one additional electronic component may be mounted on a top surface of the electronic component 110 via the additional solder bumps and additional wires embedded within the electronic component 110, thereby forming an electronic module having a bilayer structure on the substrate 100. Thereafter, microwave radiation may be applied, and the solder bumps 111 and the additional solder bumps may be selectively heated by the flux material 112 and the additional flux material, while the substrate 100, the electronic component 110, and the additional electronic component are hardly heated by the microwave radiation. Different from the conventional heating process applied to the entire electronic device, the selective heating of the solder bumps 111, the additional solder bumps, the flux material 112, and the additional flux material by the microwave radiation may reduce the warping problems of the substrate 100, the electronic component 110, and the additional electronic component. Further, since the flux material 112 and the additional flux material are heated simultaneously, the additional solder bumps and the solder bumps 111 may also be heated simultaneously, which makes the reflow soldering process of the solder bumps in the electronic module having a bilayer more uniform. It can be appreciated that when needed, the reflow soldering process may be simultaneously performed on the solder bumps in a structure with more than two layers.

[0028] After the solder bumps 111 are reflow soldered by the microwave radiation, an encapsulation layer may be formed on the substrate 100 to encapsulate the at least one electronic component 110, thereby forming an electronic packaging device. In some other embodiments, the method for forming an electronic packaging device may not include the process of forming an encapsulation layer.

[0029] In some embodiments, the method may be used to form electronic devices having a smaller size and a complex structure, such as system-in-package (SIP) devices having various electronic components 110. In other embodiments, the electronic device may be applied in any device where warping problems need to be reduced. For example, the electronic device may be a double-sided electronic device, and correspondingly, the rear surface of the substrate may also serve as another platform, and electronic components may be mounted on the another platform via solder bumps and the flux material coated thereon. The solder bumps and the flux material on the front surface and the rear surface of the substrate may be simultaneously heated by the microwave radiation to form electrical connections between the electronic components and the interconnecting lines within the substrate.

[0030] Figure 2 Shows steps of microwave radiation in a method for forming an electronic device according to a second embodiment of the present application. Figure 2 The steps shown may be performed after Figures 1A to 1Dbe implemented after the steps shown, instead of Figure 1E and 1F the steps shown and as Figures 1A to 1F an alternative embodiment of the embodiment shown in

[0031] In Figure 2 the embodiment shown, after mounting at least one electronic component 110 to the front surface of the substrate 100 via solder bumps 111 and flux material 112, the substrate 100 is loaded onto a susceptor 220 such that the back surface of the substrate 100 contacts the susceptor 220. The susceptor 220 may comprise a polar material, a combination of multiple polar materials, or a combination of a polar material and a non-polar material, which can be heated by microwave radiation. Additionally, the susceptor 220 may comprise one or more thermally conductive materials capable of enabling sufficient convective heat transfer from the susceptor 220 to the solder bumps 111 and the flux material 112 and capable of slowing down the heat dissipation of the solder bumps 111 and the flux material 112 from the back surface of the substrate 100. In some embodiments, a large portion (e.g., greater than 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, 95 wt.% or 99 wt.%) of the susceptor 220 is formed of a polar material, which enables the susceptor 220 to have good heating performance when exposed to microwave radiation. More specifically, the susceptor 220 may comprise at least one polar material of silicon carbide, graphite, polar charcoal, and polar carbon. In some other embodiments, the susceptor 220 may comprise a non-polar substrate coated with or having a polar material distributed therein, which can reduce the requirements for the material of the susceptor 220 and achieve better mechanical support and lower cost (if an appropriate material is used as the material of the non-polar substrate) during the heating step of the solder bumps 111 and the flux material 112. Specifically, the non-polar substrate may comprise a silicon wafer or silicon powder, and the polar coating may comprise at least one polar material of silicon carbide, graphite, polar charcoal, or polar carbon.

[0032] Next, still referring to Figure 2, microwave radiation is applied to at least one electronic component 110 to heat the solder bumps 111 through the flux material 112. At the same time, the susceptor 220 is also exposed to the microwave radiation, where the microwave radiation can penetrate through at least one electronic component 110 and the substrate 100 and finally reach the susceptor 220. In addition, the microwave radiation can also directly reach the susceptor 220 from the lateral and bottom surfaces of the susceptor 220 that are not blocked by the substrate 100. Since the susceptor 220 is at least partially formed of a polar material, the dipoles within the polar molecules of the susceptor 220 are sensitively induced by the electric field of the microwave, thereby generating thermal energy in the susceptor 220. In some embodiments, the heat generated in the susceptor 220 can be transferred to the flux material 112 and the solder bumps 111 in a convective manner, thus providing additional thermal energy for the solder bumps 111 to facilitate their reflow soldering process. In this way, the flux material 112 and the solder bumps 111 can be heated by a hybrid heating mechanism that combines the direct microwave curing of the flux material 112 and the solder bumps 111 and the thermal energy transferred from the susceptor 220 by convection. Further, the heated susceptor 220 can also slow down the heat dissipation that the flux material 112 and the solder bumps 111 may undergo through the substrate 100, thereby helping to promote the reflow soldering process. Therefore, the reflow soldering process can have higher energy efficiency and thus lower energy requirements for the microwave source. In addition, the bottom portions of the flux material 112 and the solder bumps 111 are less exposed to the microwave radiation (due to being blocked by the electronic component 110), yet they can receive more thermal energy transferred from the susceptor 220 by convection, so that the flux material 112 and the solder bumps 111 can be heated in a more uniform and controllable manner and with fewer defects present. Simply put, the excess microwave energy that cannot be absorbed by the flux material 112 and the solder bumps 111 can be collected by the susceptor 220 and converted into heat, which in turn helps the reflow soldering process of the solder bumps 111. Then, the solder bumps 111 start to melt and reform during the reflow soldering process of the solder bumps 111, so that the reflowed solder bumps 111 form an electrical connection between the interconnect 101 and the electronic component 110. In some embodiments, the susceptor 220 can include a film or plate at its bottom that can reflect microwaves upward. During the reflow soldering process, the reflected microwaves can penetrate the susceptor 220 again and generate thermal energy there, and even penetrate the susceptor 220 and reach the flux material 112 and the solder bumps 111 to contribute to the heating process of the flux material 112 and the solder bumps 111. In some embodiments, the susceptor 220 heated by the microwave radiation can reach a temperature within the range of 50°C to 200°C. In a preferred embodiment, the susceptor 220 heated by the microwave radiation can reach a temperature within the range of 50°C to 120°C, which enables the solder bumps 111 to be fully reflow soldered while alleviating the warping of the device in the most controllable manner.

[0033] In some other embodiments, the susceptor 220 can be attached to the top surface of the electronic component 110. When microwave radiation is applied, the susceptor 220 containing at least one polar material can be heated. Since the susceptor 220 is in direct contact with the electronic component 110, the heated susceptor 220 can make the heat energy transferred to the flux material 112 and the solder bumps 111 by convection more sufficient, and slow down the heat dissipation of the flux material 112 and the solder bumps 111, thereby contributing to the reflow soldering process of the solder bumps 111. In addition, since the substrate 100 does not transfer heat energy, warping of the substrate 100 can be avoided or reduced. In some embodiments, the susceptor 220 heated by microwave radiation can reach a temperature in the range between 50°C and 200°C. In a preferred embodiment, the susceptor 220 heated by microwave radiation can reach a temperature in the range between 50°C and 120°C, which can relieve the warping of the device in the most controllable manner.

[0034] Although the exemplary methods for forming electronic devices of the present application are described in conjunction with the corresponding figures, those skilled in the art will understand that the methods for forming electronic devices can be modified and adapted without departing from the scope of the present invention.

[0035] The various embodiments have been described herein with reference to the accompanying drawings. However, it will be understood that various modifications and changes can be made thereto, and additional embodiments can be implemented, without departing from the broader scope of the invention as set forth in the appended claims. In addition, by considering the specification and practice of one or more embodiments of the invention disclosed herein, other embodiments will be apparent to those skilled in the art. Therefore, it is intended that the present application and the examples herein be considered as exemplary only, with the true scope and spirit of the invention being indicated by the list of exemplary claims appended hereto.

Claims

1. A method for forming an electronic device, characterized in that, The method includes: providing a substrate having a front surface, wherein the substrate includes at least one non-polar material; providing at least one electronic component having solder bumps mounted on its rear surface, wherein the solder bumps are coated with a flux material, the flux material includes at least one polar material, and the at least one electronic component includes at least one non-polar material; placing the at least one electronic component onto the front surface of the substrate via the solder bumps; and applying microwave radiation to the at least one electronic component to heat the solder bumps through the flux material.

2. The method according to claim 1, characterized in that, The solder bumps include metal powder.

3. The method according to claim 1, wherein The solder bumps include metal powder and an adhesive material that glues the metal powder.

4. The method according to claim 3, wherein The adhesive material includes a thermally conductive material.

5. The method according to claim 4, wherein The adhesive material includes a polar material.

6. The method according to claim 1, characterized in that The flux material includes at least one polar material, and the degree of polarization of the polar material is higher than that of the solder bumps.

7. The method according to claim 6, wherein The flux material includes one or more materials selected from the following combinations: nonylphenol ethoxylate, glycerol monostearate, acid activator, water, and inorganic salts.

8. The method according to claim 7, characterized in that, The flux material includes nonylphenol ethoxylate between 40 wt.% and 70 wt.%, glycerol monostearate between 10 wt.% and 30 wt.%, acid activator between 3 wt.% and 10 wt.%, water between 3 wt.% and 10 wt.%, and inorganic salts between 4 wt.% and 15 wt.%.

9. The method according to claim 1, wherein The applied frequency range of the microwave radiation is between 1 GHz and 10 GHz.

10. The method according to claim 1, wherein During the step of applying the microwave radiation to the at least one electronic component, the microwave radiation is applied at a variable frequency.

11. The method according to claim 1, characterized in that, The process of applying microwave radiation to the at least one electronic component includes: placing a microwave source above the front surface of the at least one electronic component; and applying the microwave radiation from the microwave source to the at least one electronic component.

12. The method according to claim 1, characterized in that The at least one electronic component includes a semiconductor package.

13. The method according to claim 1, characterized in that, The method further includes: forming an encapsulation layer on the substrate to encapsulate the at least one electronic component.

14. The method according to claim 1, wherein Before applying microwave radiation to the at least one electronic component, the method further includes: loading the substrate onto a carrier, and the carrier includes at least one polar material.

15. The method according to claim 14, wherein The carrier includes one or more thermally conductive materials.

16. The method according to claim 14, wherein The carrier includes at least one polar material selected from silicon carbide, graphite, polar charcoal, and polar carbon.

17. The method according to claim 14, characterized in that, The carrier includes a non-polar substrate coated with a polar material.

18. The method according to claim 17, wherein The non-polar substrate includes a silicon wafer or silicon powder, and the polar coating includes at least one polar material selected from silicon carbide, graphite, polar charcoal, and polar carbon.

19. The method according to claim 14, wherein The process of loading the substrate onto the carrier includes: loading the substrate onto the carrier such that the rear surface of the substrate contacts the carrier.

20. The method according to claim 14, wherein The process of loading the substrate onto the carrier includes: loading the substrate onto the carrier such that the top surface of the electronic component contacts the carrier.

21. An electronic device, characterized in that, The electronic device is formed using the method according to any one of claims 1 to 20.

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