Method for mounting electronic device on flexible substrate and electronic package

Abstract

The invention discloses a method for mounting an electronic device on a flexible substrate and an electronic package formed according to the method. The method comprises the following steps of: providing a flexible substrate, wherein a conductive pattern is arranged on the front surface of the flexible substrate; forming a solder bump on the conductive pattern; arranging a thermosetting material on the front surface of the flexible substrate; bonding the electronic device on the front surface of the flexible substrate through the solder bump and the thermosetting material; heating the flexible substrate to a first temperature to cure the thermosetting material; and heating the flexible substrate to a second temperature to reflow the solder bumps, wherein the second temperature is higher than the first temperature.

Description

Technical Field

[0001] The present invention relates to semiconductor technology, and more particularly to a method for mounting electronic devices on a flexible substrate and an electronic package. Background Art

[0002] The semiconductor industry faces increasingly complex integration challenges as consumers expect their electronic products to be smaller, faster, have higher performance, and pack more and more functionality into a single device.

[0003] SMT, known as surface mount technology, is a popular device mounting technology and process in the electronic packaging industry. It is a packaging technology that can mount surface mount components or devices (SMC / SMD) without pins or short leads on the surface of a printed circuit board (PCB) or other substrate, and assemble them by reflowing the solder material pre-deposited on the PCB.

[0004] However, it is worth noting that when SMC / SMD is mounted on a flexible substrate (such as polyimide tape), especially for large SMC / SMC, cold solder joints often occur, which will result in low yield and poor reliability of electronic packages assembled using the SMT process.

[0005] Therefore, it is necessary to further improve the traditional SMT process. Summary of the invention

[0006] An object of the present application is to provide a surface mounting method with high reliability.

[0007] According to one aspect of the present application, a method for mounting an electronic device on a flexible substrate is disclosed. The method includes: providing a flexible substrate having a conductive pattern on the front side; forming a solder bump on the conductive pattern; disposing a thermosetting material on the front side of the flexible substrate; bonding the electronic device to the flexible substrate via the solder bump and the thermosetting material; heating the flexible substrate to a first temperature to cure the thermosetting material; heating the flexible substrate to a second temperature to reflow the solder bump, the second temperature being higher than the first temperature.

[0008] According to another aspect of the present application, a method for mounting an electronic device on a flexible substrate is also disclosed, the method comprising: providing a flexible substrate having a conductive pattern on the front side thereof; forming a solder bump on the conductive pattern; disposing a thermosetting material on the bottom surface of the electronic device; bonding the bottom surface of the electronic device to the front side of the flexible substrate via the solder bump and the thermosetting material; heating the flexible substrate to a first temperature to cure the thermosetting material; heating the flexible substrate to a second temperature to reflow the solder bump, the second temperature being higher than the first temperature.

[0009] According to another aspect of the present application, an electronic package manufactured by the method according to the above aspect of the present application is disclosed.

[0010] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and do not limit the present invention. In addition, the accompanying drawings, which are incorporated in this specification and constitute a part of this specification, illustrate embodiments of the present invention and together with the description are used to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings referred to herein form part of the specification. The features shown in the drawings illustrate only some embodiments of the present application, rather than all embodiments of the present application, unless the specific implementation mode clearly indicates otherwise, and the reader of this specification should not make an inference to the contrary.

[0012] Figure 1 Three states of manufacturing antenna package using traditional SMT process are shown.

[0013] Figure 2 Three states of manufacturing an antenna package according to a method for mounting an electronic device on a flexible substrate according to an embodiment of the present application are shown.

[0014] FIG. 3A to FIG. 3F A side view showing various steps in a method for mounting an electronic device on a flexible substrate according to an embodiment of the present application is shown.

[0015] Figure 4 and Figure 5 Two further exemplary arrangements of thermoset material are shown that are disposed on a flexible substrate to maintain adhesion between the flexible substrate and electronic devices mounted on the substrate.

[0016] FIG. 6A to FIG. 6J Various steps of a method for manufacturing an electronic package according to an embodiment of the present application are shown.

[0017] 7A to 7I Various steps of a method for manufacturing an electronic package according to an embodiment of the present application are shown.

[0018] The same reference numbers will be used throughout the drawings to refer to the same or like parts. DETAILED DESCRIPTION

[0019] The following detailed description of the exemplary embodiments of the present application refers to the accompanying drawings, which constitute a part of the specification. The accompanying drawings show specific exemplary embodiments in which the present application can be practiced. The detailed description including the accompanying drawings describes these embodiments in sufficient detail to enable those skilled in the art to implement 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, readers of the following detailed description should not interpret this specification in a limiting sense, and only the attached claims define the scope of the embodiments of the present application.

[0020] In this application, unless otherwise expressly stated, the use of the singular includes the plural. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms such as "including" and "comprising" is not restrictive. In addition, unless otherwise specifically stated, terms such as "element" or "component" cover both elements and components that contain one unit and elements and components that contain more than one unit. The section headings used herein are for organizational purposes only and should not be construed as limiting the desired subject matter in any way.

[0021] As used herein, for ease of description, spatially relative terms such as "under," "below," "above," "above," "up," "upper," "lower," "left," "right," "vertical," "horizontal," "side," etc. may be used herein to describe the relationship of one element or feature to another element (or elements) or feature (or features), as illustrated in the drawings. In addition to the orientation depicted in the figures, spatially relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein may also be interpreted accordingly. It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, the element may be directly connected or coupled to the other element, or there may be intermediate elements.

[0022] As described above, the inventors of the present application have noticed that when SMC / SMD is mounted on a flexible substrate using a conventional SMT process, cold solder joints often occur, especially for large SMC / SMD.

[0023] Figure 1 Figure 3 shows three states of antenna packaging made using traditional SMT technology. Figure 1As shown, in state 1, the antenna module 110 is adhered to the flexible substrate 120 through the solder bump 130. At room temperature, the flexible substrate 120 does not deform, so the bonding between the antenna module 110 and the flexible substrate 120 is good. However, the flexible substrate 120 and the solder bump 130 need to be reflowed to melt the solder bump 130 to achieve a better metallurgical connection. During the reflow process, the temperature of the antenna package can be increased according to a predetermined heating curve. In particular, in state 2, when the temperature increases from room temperature to a value that is not high enough, such as below the material melting point of the solder bump 130, the flexible substrate 120 may be slightly deformed or warped due to the mismatch of the thermal expansion coefficient (CTE) of the antenna module 110 and the flexible substrate 120. In state 2, since the solder bump 130 is not melted, the antenna module 110 can still be well connected to the flexible substrate 120 without undesired movement relative to the flexible substrate 120. As the reflow operation proceeds and the temperature increases, for example, to a value higher than the melting point of the solder bump 130, the solder bump 130 begins to melt. At the same time, due to the significant mismatch in CTE between the antenna module 110 and the flexible substrate 120, especially when the flexible substrate 120 is much thinner and softer than the antenna module 110, the flexible substrate 120 may bend significantly, thereby generating a shear force, which causes the antenna module 110 to separate from the flexible substrate 120 at some of the melted solder bumps 130. In other words, a cold solder joint is formed between the antenna module 110 and the flexible substrate 120, which results in a low yield and poor reliability of the antenna package.

[0024] In order to solve the above problems, the inventors of the present application have proposed a new method for mounting an electronic device on a flexible substrate. In particular, a thermosetting material is introduced between the electronic device and the flexible substrate, which can fix the electronic device on the flexible substrate before the solder bump begins to melt during the reflow operation. The thermosetting material has a thermosetting property, that is, it can be cured at a thermosetting temperature. The thermosetting temperature of the thermosetting material can be lower than the melting temperature of the solder bump. In this way, when the solder bump has not yet melted, the thermosetting material has already cured and solidified, so that the electronic device can be firmly bonded to the flexible substrate.

[0025] Figure 2 1 shows three states of manufacturing an antenna package by a method according to an embodiment of the present application. Figure 2As shown, in state 1, the antenna module 210 is bonded to the flexible substrate 220 via the solder bump 230 and the thermosetting material 240. Then, a reflow operation is performed on the flexible substrate 220 and the solder bump 230 to melt the solder bump 230. During the reflow operation, the temperature gradually increases. In state 2, when the temperature is not high enough but reaches the thermosetting temperature of the thermosetting material 240, the flexible substrate 220 may be slightly warped. At the same time, the thermosetting material 240 is cured and solidified. Therefore, the antenna module 210 can maintain a good connection with the flexible substrate 220. As the reflow operation proceeds, when the temperature reaches the melting point of the solder bump 230, the solder bump 230 begins to melt. Figure 1 Unlike the state 3 of the antenna package shown in FIG, even if the flexible substrate 220 may be significantly bent, the antenna module 210 will not be separated from the flexible substrate 220 because they are firmly connected to each other by the cured thermosetting material 240. Therefore, even if the solder bump 230 melts, the conductive pattern (e.g., the conductive pad of the antenna module 210) and the flexible substrate 220 will not move relative to each other, and thus a cold solder joint will not occur.

[0026] refer to FIG. 3A to FIG. 3F , showing side views of various steps of a method for mounting an electronic device (eg, an antenna module) on a flexible substrate.

[0027] like Figure 3A As shown, a flexible substrate 310 is provided, such as a polyimide film. The flexible substrate 310 may include a plurality of conductive patterns 312 on the front side, such as contact pads. The flexible substrate 310 may also include one or more dielectric layers and one or more conductive layers located between and through the dielectric layers. The conductive layers may define pads, traces, and plugs, and electrical signals or voltages may be distributed horizontally and vertically across the redistribution structure via the pads, traces, and plugs. In some embodiments, the flexible substrate 310 may be much thinner than the electronic device to be mounted thereon. For example, the flexible substrate 310 may be thinner than 30% of the thickness of the electronic device to be mounted, or thinner than 10%.

[0028] Then, if Figure 3B As shown, solder bumps 320 may be formed on the flexible substrate 310. For example, solder paste may be printed on the corresponding conductive pattern 312 on the front side of the flexible substrate 310 to form the solder bumps 320. Therefore, the solder bumps 320 may have the same layout as the conductive pattern 312.

[0029] In some alternative embodiments, the solder bumps 320 may be formed on the flexible substrate 310 using one or a combination of the following processes: evaporation, electrolytic plating, chemical plating, ball drop or screen printing process. The solder paste material may be Al, Sn, Ni, Au, Ag, lead (Pb), bismuth (Bi), Cu or any combination thereof, with an optional flux solution. In some embodiments, the solder bumps 320 may take the form of ball bumps, column bumps, micro bumps or any other similar shapes. It is understood that the solder bumps 320 may be reflowed by being heated to or above their melting point.

[0030] Next, if Figure 3C As shown, after forming the solder bump 320, a thermosetting material 330 such as epoxy resin can be arranged on the front side of the flexible substrate 310, for example, by dipping or printing. In some embodiments, the thermosetting material 330 can be arranged in the form of dots, lines or other suitable shapes. Preferably, the thermosetting material 330 can be arranged in a planar layout, for example, the planar layout of the thermosetting material 330 can include three or more dots that are not arranged on the same line. It is understood that the thermosetting material 330 is usually in the same plane as the solder bump 320, so that the thermosetting material 330 can maintain the alignment and bonding between the flexible substrate 310 and the electronic device to be installed.

[0031] Thermosetting material 330 may be disposed beside or near each solder bump 320 so that the electronic device to be mounted later can cover the thermosetting material 330 and the solder bump 320. For example, the thermosetting material 330 may be disposed between every two adjacent solder bumps 320, or disposed around the solder bumps 320. In some embodiments, at least some of the thermosetting material 330 may be disposed on the periphery of the entire solder bump 320 layout on the flexible substrate 310. Preferably, the diameter of the thermosetting material 330 may be smaller than the spacing between two adjacent solder bumps 320, so that the thermosetting material 330 will not adhere to the solder bump 320 in the subsequent solder bump 320 reflow process.

[0032] Then, if Figure 3D As shown, the electronic device 340 is mounted on the front side of the flexible substrate 310. The electronic device 340 may have a conductive pattern (not shown) that can be connected to the conductive pattern of the flexible substrate 310 via corresponding solder bumps 320. In some embodiments, the electronic device 340 may be an antenna module. For example, the antenna module may include an antenna encapsulated in a sealed mold. It can be seen that the thermosetting material can be arranged roughly in a layout aligned with the periphery of the electronic device 340.

[0033] Then, the flexible substrate 310 and the components and electronic devices attached thereto are subjected to a reflow operation. The reflow operation may gradually increase the temperature of the flexible substrate 310. Figure 3E As shown, the temperature of the flexible substrate 310 can reach a first temperature to cure the thermosetting material 330. For example, the first temperature can be higher than the thermosetting temperature of the thermosetting material 33, but can be lower than the melting point of the solder bump 320. In this way, the thermosetting material 330 can be cured and solidified, so that the electronic device 340 is firmly bonded to the flexible substrate 310. It can be understood that the first temperature can depend on the thermosetting properties of the thermosetting material 330. In an example where the thermosetting material 330 is an epoxy resin, the first temperature can be in the range of 110 to 180 degrees Celsius, or preferably in the range of 110 to 140 degrees Celsius. In some embodiments, the temperature of the flexible substrate 310 can be continuously maintained at the first temperature for a predetermined time, for example, more than 30 seconds, more than 2 minutes, more than 5 minutes, or more than 15 minutes, to allow the thermosetting material 330 to be completely thermally cured. At this time, since the temperature of the flexible substrate 310 has not yet reached the melting point of the solder bump 320, the solder bump 320 will not be melted. Therefore, even if the flexible substrate 310 is subsequently warped or even bent, the cured thermosetting material 330 can firmly fix the electronic device on the flexible substrate 310 .

[0034] Then, continue with the reflow operation. Figure 3F As shown, the temperature of the flexible substrate 310 is increased to the second temperature to reflow the solder bump 320. The second temperature is higher than the first temperature, and in particular, higher than the melting point of the solder bump 320. The solder bump 320 begins to melt, while the thermosetting material 330 continues to hold the electronic device 340. After the solder bump 320 begins to solidify and finally solidifies, the flexible substrate 310 and the electronic device 340 are more firmly assembled to each other. The combination of the solder bump 320 and the thermosetting material 330 effectively avoids the cold solder joint caused by the warping of the flexible substrate 310 at the high reflow temperature.

[0035] It is understandable that despite Figures 3A to 3F In the illustrated embodiment, the thermosetting material is formed on the flexible substrate, but in some alternative embodiments, the thermosetting material may also be disposed on the surface (e.g., bottom surface) of the electronic device, and the electronic device is connected to the front surface of the flexible substrate through the surface. It is understood that when the thermosetting material is disposed, the conductive areas of the flexible substrate and the electronic device need to be avoided.

[0036] The thermoset material may also be disposed on the flexible substrate in a variety of layouts. In some examples, the layout of the thermoset material may depend on the form factor of the electronic device and / or the layout of solder bumps between the electronic device and the flexible substrate.

[0037] Figure 4 and Figure 5 Two additional exemplary layouts of thermoset material are shown that may be formed on a flexible substrate to maintain adhesion between the flexible substrate and an electronic device mounted thereon.

[0038] like Figure 4 , a top view of a flexible substrate strip 410 is provided. The flexible substrate strip 410 may have a plurality of sets of repeating conductive patterns 412 on its front side. Solder paste may be printed or otherwise deposited on the conductive patterns 412 to form solder bumps 420 for further bonding electronic devices (not shown). In this embodiment, a thermosetting material may be disposed at corresponding centers of some conductive patterns 412 on the front side of the flexible substrate strip 410. The thermosetting material may take the form of, for example, dots. Thus, a plurality of dots of the thermosetting material may be generally distributed laterally on the front side of the flexible substrate strip 410. In this way, during the reflow operation of the solder bumps, the thermosetting material that has solidified before the solder bumps melt may securely hold the electronic devices on the flexible substrate 410. It will be appreciated that three or more dots of the thermosetting material 430 may provide better bonding than one or two dots.

[0039] exist Figure 5 In another example shown, a top view of a flexible substrate 510 is provided. The flexible substrate 510 has a set of conductive patterns on its front side. Solder bumps 520 are formed on each corresponding conductive pattern. In addition, the thermosetting material 530 can surround the solder bumps 520 and be distributed at the four corners on the front side of the flexible substrate 510 and the center of the flexible substrate 510. This planar layout of the thermosetting material 530 can ensure that the electronic device is firmly bonded to the flexible substrate 510, regardless of whether the flexible substrate 510 is bent in any way.

[0040] The electronic packages obtained by the methods of some embodiments of the present application and the conventional methods were subjected to shear tests. The shear test was performed using a Dage-4000 shear tester, which can provide a shear rate of 700 μm / s and a maximum shear force of 5 kilograms of force (kgF). The shear force was gradually applied to the electronic package. Table 1 below shows the experimental results of the shear test.

[0041] Table 1 Experimental results of shear test

[0042]

[0043] As shown in Table 1, for electronic packages manufactured using conventional methods, they can only withstand an average shear strength of 790.8 grams of force. However, for electronic packages manufactured using the method of the present application, they can withstand a shear strength of more than 5 kilograms of force. It can be seen that the welding of the electronic packages manufactured using the method of the present application is significantly better, and the reliability is significantly improved.

[0044] The method for mounting electronic devices in the present application can be applied to the production and manufacture of various electronic packages. FIG. 6A to FIG. 6J , which shows the various steps of a method for manufacturing an electronic package according to an embodiment of the present application.

[0045] Reference Fig. 6A , a substrate strip including a plurality of substrate assemblies is provided. In some embodiments, the plurality of substrate assemblies of the substrate strip can be arranged in a row and connected in a series. In some other embodiments, the plurality of substrate assemblies of the substrate strip can be arranged in an array having a plurality of rows and a plurality of columns. In this way, a plurality of substrate assemblies can be processed simultaneously to improve manufacturing efficiency.

[0046] exist Fig. 6A In the illustrated embodiment, the substrate strip includes two substrate components, and the two substrate components are separated from each other by a split channel 614. The split channel 614 can provide a cutting area to split the substrate strip into two separate substrate components. In some embodiments, the split channel 614 can be made of a rigid material. In some alternative embodiments, the split channel 614 can be made of a flexible material, such as polyimide or other similar polymer materials. Since the split channel 614 needs to be cut or otherwise damaged in subsequent steps, preferably, the split channel 614 is made of a material that is easy to cut in, for example, a laser ablation process.

[0047] Each substrate assembly includes a first substrate 601, a second substrate 602, and a flexible connector 603 disposed between the first substrate 601 and the second substrate 602. The first substrate 601 and the second substrate 602 may be a rigid printed circuit board (PCB) or a flexible printed circuit board (FPC).

[0048] Various electronic devices can be mounted on the first substrate 601 and the second substrate 602. Specifically, the first substrate 601 includes a first mounting surface 6011, and the second substrate 602 includes a second mounting surface 6021, wherein the second mounting surface 6021 and the first mounting surface 6011 are not on the same side of the substrate assembly. Fig. 6AAs shown, when the substrate strip is placed on a first carrier 604, such as a metal or glass carrier, the first mounting surface 6011 of the first substrate 601 faces away from the first carrier 604, that is, facing upward, and the second mounting surface 6021 of the second substrate 602 faces the first carrier 604, that is, facing downward. One or more signals can be transmitted through the flexible connector 603, including but not limited to power signals and control signals. In some embodiments, the signal is transmitted through one or more separate wires or cables of the flexible connector 603, and the signal transmission in the flexible connector 603 can be bidirectional. For example, the flexible connector 603 can be a flexible cable or a flexible circuit board.

[0049] Afterwards, if Figure 6B As shown, a plurality of solder bumps 606 are formed on the first mounting surface 6011 of each first substrate 601. The solder bumps 606 can be formed using one or any combination of the following processes: evaporation, electrolytic plating, chemical plating, ball drop or screen printing process. The conductive solder bump material can be Al, Sn, Ni, Au, Ag, lead (Pb), bismuth (Bi), Cu, solder or a combination thereof, with an optional flux solution. For example, the solder bump material can be eutectic Sn / Pb, high lead solder or lead-free solder. In some embodiments, the solder bump material can be bonded to the first mounting surface 3011 of each first substrate 301 using a suitable attachment or bonding process. In one embodiment, the bump material can be reflowed to form a conductive ball or bump by heating the material above its melting point.

[0050] Further, after forming the solder bumps 606, a thermosetting material 617, such as epoxy resin, is disposed on the first mounting surface 6011 of each first substrate 601 by, for example, dipping or printing. Preferably, the thermosetting material 617 is disposed in a planar layout, for example, disposed at the four corners of the first substrate 601 around the solder bumps 606. It is understood that the layout of the thermosetting material 617 is generally coplanar with the layout of the solder bumps 606, so that the thermosetting material 617 can maintain the alignment and bonding between the first substrate 601 and the electronic device to be mounted.

[0051] Afterwards, if Figure 6CAs shown, the first electronic device 607 is attached to the first mounting surface 6011 of each first substrate 601. In some embodiments, before attaching the first electronic device 607, a first substrate mask 608 having a plurality of first openings is placed on the first mounting surface 6011 of the first substrate 601. Each first opening is aligned with the first substrate 601 of the substrate assembly to expose the first mounting surface 6011 of the first substrate 601. In this way, the first electronic device 607 can be accurately mounted on the first mounting surface 6011 of the first substrate 601 through the corresponding first opening. At the same time, during the attachment process, the second substrate 602 can be covered by the first substrate mask 608.

[0052] In some embodiments, the first electronic device 607 may be an antenna mounted to the first substrate 601. In some embodiments, the antenna may be a dielectric resonator antenna (DRA) including a dielectric resonator and an antenna feeding structure. Dielectric resonators are used to transmit and receive millimeter wave antenna signals of different frequencies and / or communication protocols, and are typically made of materials with low loss and high dielectric constants. For example, dielectric resonators may be made of polymer materials. In some embodiments, the dielectric resonator antenna (DRA) may be designed into any three-dimensional shape, including, for example, a cylinder, a rectangle, a sphere, or a ring. The thickness of the antenna is significantly greater than the thickness of the first substrate 601.

[0053] In some embodiments, the first substrate mask 608 is a metal cover made of a metal material (e.g., stainless steel, aluminum, etc.) or any other suitable material (e.g., plastic) or a combination of these materials to prevent the substrate from warping during the attachment process. The first substrate mask 608 can be removed from the substrate strip after the attachment process. In this way, the first substrate mask 608 can be reused for other substrate strips to mount the first electronic device on the corresponding first substrate. However, for those substrates not covered by the first substrate mask 608, substrate warping will inevitably occur.

[0054] In some embodiments, the first carrier 604 may include a substrate strip cavity 6041 for receiving the substrate strip. The depth of the substrate strip cavity 6041 is greater than the height of the substrate strip to accommodate the entire substrate strip. In this way, the first substrate mask 608 can be supported by the first carrier 604 without direct contact with the substrate strip and without causing potential contamination to the surface of the substrate strip.

[0055] A reflow operation is performed on the substrate strip and the components and electronic devices attached thereto. The reflow operation may gradually increase the temperature of the first substrate 601. The temperature of the first substrate 601 reaches a first temperature to cure the thermosetting material 617. For example, the first temperature may be higher than the curing temperature of the thermosetting material 617 but lower than the melting point of the solder bump 606. In this way, the thermosetting material 617 is cured and solidified, so that the electronic device 607 is firmly bonded to the first substrate 601. In some embodiments, the temperature of the first substrate 601 may be maintained at the first temperature for a predetermined period of time so that the thermosetting material 617 can be completely cured. At this time, since the temperature of the first substrate 601 has not yet reached the melting point of the solder bump 606, the solder bump 606 will not be melted. Therefore, even if the first substrate 601 is subsequently warped or even bent, the cured thermosetting material 617 can firmly fix the electronic device 607 on the first substrate 601.

[0056] The reflow operation continues. The temperature of the first substrate 601 is increased to the second temperature to reflow the solder bump 606. The solder bump 606 begins to melt, while the thermosetting material 617 continues to hold the electronic device 607. After the solder bump 606 begins to solidify and finally solidifies, the first substrate 601 and the electronic device 607 are more firmly assembled to each other.

[0057] Next, a sealant 609 such as an underfill material is injected into the gap between the first electronic device 607 and the first mounting surface 6011 of the first substrate 601 to ensure that the sealant 609 completely fills the space around the plurality of solder bumps 606 .

[0058] like Fig. 6E As shown, the first substrate mask 608 is removed from the first stage 604. Then, the substrate strip is flipped and placed on a second stage 612 having a plurality of cavities 6121. In this way, the first mounting surface 6011 of each first substrate 601 faces the second stage 612, i.e., faces the downward direction, and the second mounting surface 6021 of the second substrate 602 faces away from the second stage 612, i.e., faces the upward direction. Therefore, the first substrate 601 can substantially cover the opening of the cavity 6121, and its outer edge is supported by the edge of the cavity 6121. In this way, the first substrate 601 can be at the same level as the second substrate 602, which is conducive to further processing of the substrate strip (e.g., solder printing).

[0059] like Fig. 6E As shown, since the cavity 6121 of the second carrier 612 accommodates the protruding structure (i.e., the first electronic device) on one side of the substrate strip, a substantially flat profile can be formed on the other side of the substrate strip during the manufacturing process, thereby enabling mass production on various substrate components at the same time.

[0060] Afterwards, if Fig. 6F As shown, a plurality of solder bumps 615 are formed on the second mounting surface 6021 of the second substrate 602. Fig. 6F As shown, the plurality of solder bumps 615 may have Figure 6B The same or similar structures of the plurality of solder bumps 606 are shown, and are not described in detail herein. In some embodiments, the thermosetting material is not disposed on the second substrate 602, but in some other embodiments, the thermosetting material can be disposed around the solder bumps 615 in a manner similar to the thermosetting material on the first substrate.

[0061] like Figure 6G As shown, the second electronic device 610 is attached to the second mounting surface 6021 of the second substrate 602. In some embodiments, similar to the first substrate mask 608, a second substrate mask 613 having a plurality of second openings is also placed on the second mounting surface 6021 of the second substrate 602, and each second opening is aligned with the second substrate 602 of the substrate assembly. The second openings can expose the second mounting surface 6021. Then, the second electronic device 610 is mounted on the second mounting surface 6021 of the second substrate 602 through the corresponding second openings.

[0062] like Figure 6H As shown, each second electronic device 610 is clamped on the corresponding second mounting surface 6021 by a plurality of solder bumps 615. For example, the corners of the second electronic device 610 may be pressed against the solder bumps 615. Next, a sealant 616 is injected into the gap between the second electronic device 610 and the second mounting surface 6021 of the second substrate 602 to ensure that the sealant 616 completely fills the space around the solder bumps 615. After the sealant 616 is injected, the sealant 616 is cured or heated.

[0063] like Fig.6I As shown, the second substrate mask is removed from the second stage 612 and the substrate strip is unloaded from the second stage 612, and then the substrate strip is divided into various substrate components from each division channel. Specifically, the laser ablation tool 611 can be used to Fig.6I The substrate strip shown is divided into substrate components. In some embodiments, a mechanical saw blade can also be used to mechanically divide the dividing channel. Figure 6J As shown, the flexible connector 603 of each substrate assembly may be bent or cured to form an electronic package having two substrates that are perpendicular to each other.

[0064] 7A to 7I It is a schematic side view of each step of another embodiment of a method for manufacturing an electronic package according to the present application.

[0065] like Fig. 7AAs shown, a first substrate 702 is provided, which may be a rigid substrate. A solder bump 704 is formed on the first substrate 702, and a thermosetting material 706 is further formed. It is understood that a plurality of first substrates 702 may be similarly formed with corresponding solder bumps 704 and thermosetting materials 706.

[0066] Then, if Figure 7B As shown, the first substrate 702 may be mounted on a substrate strip 710, which may be a flexible substrate strip. Solder bumps 704 and thermosetting material 706 may be connected to the substrate strip 710 to support the first substrate 702 thereon.

[0067] like Figure 7C As shown, a reflow operation is performed on the substrate strip 710 and the first substrate 702 attached thereto. The reflow operation can gradually increase the temperature of the substrate strip 710 and the first substrate 702. The temperature of the first substrate 702 reaches a first temperature to cure the thermosetting material 706. In this way, the thermosetting material 706 is cured and solidified, so that the substrate strip 710 is firmly bonded to the first substrate 701. Since the first substrate 702 is bonded to the substrate strip 710 through the cured thermosetting material 706, reflow of the solder bumps 710 is not desired at this stage. It can be understood that the curing temperature of the thermosetting material 706 is not very high, so the warping of the flexible substrate strip 710 is not obvious.

[0068] Then, if Fig.7D As shown, the substrate strip 710 is turned over and placed on a carrier 712. The carrier 712 has a cavity for accommodating the first substrate 702. In this way, other components or substrates can be further mounted on the other side of the substrate strip 710. In particular, as Fig. 7E As shown, a plurality of second substrates 716 can be mounted on the substrate strip 710, wherein each second substrate 716 has some electronic devices mounted thereon. In other words, the second substrates 716 can be prefabricated before being mounted on the substrate strip 710, so they can contain complex structures such as devices and antennas and have greater thickness and stronger rigidity. However, since the first substrate 702 has been mounted on the substrate strip 710, the warping of the substrate strip 710 can be significantly suppressed by the first substrate. Fig. 7E In the illustrated embodiment, the second substrate 716 may be mounted on the substrate strip 710 without the thermoset material 716 , while in other embodiments, the second substrate 716 may be mounted on the substrate strip 710 including the thermoset material and the solder bumps 718 .

[0069] Next, if Figure 7FAs shown, a reflow operation of solder bumps 704 and 718 on both sides of substrate strip 710 is performed. In some embodiments, solder bumps 704 and 718 are made of the same solder material, and the reflow operation can be performed at a temperature higher than the melting point of the solder of solder bumps 704 and 718. In some embodiments, solder bumps 704 and 718 are made of different solder materials, and the reflow operation can be performed at a temperature higher than the melting point of the higher solder of solder bumps 704 and 718. In any case, solder bumps 704 and 718 will solidify after the reflow operation.

[0070] After the reflow operation is completed, Figure 7G As shown, bottom filling material 720 is filled between the second substrate 716 and the substrate strip 710 to strengthen their connection. Figure 7H As shown, using, for example, a laser ablation tool 722, the substrate strip 710 is separated into individual electronic packages through each separation channel. Fig.7I The electronic package shown.

[0071] The discussion herein includes a number of illustrative drawings that show various portions of methods for mounting electronic devices on flexible substrates. For ease of illustration, these figures do not show all aspects of each example assembly. Any of the example assemblies and / or methods provided herein may share any or all characteristics with any or all other assemblies and / or methods provided herein.

[0072] Various embodiments have been described herein with reference to the accompanying drawings. However, it will be appreciated that various modifications and variations may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the appended claims. In addition, other embodiments will be apparent to those skilled in the art by consideration of the specification and practice of one or more embodiments of the invention disclosed herein. Therefore, it is intended that the present application and the examples herein be considered merely exemplary, with the true scope and spirit of the invention being indicated by the list of the appended exemplary claims.

Claims

1. A method for mounting an electronic device on a flexible substrate, the method comprising: Providing a flexible substrate, the front side of which has a conductive pattern; forming solder bumps on the conductive pattern; Disposing a thermosetting material on the front side of the flexible substrate; bonding the electronic device to the front side of the flexible substrate via the solder bumps and the thermosetting material; heating the flexible substrate to a first temperature to cure the thermosetting material; as well as The flexible substrate is heated to a second temperature to reflow the solder bumps, the second temperature being higher than the first temperature.

2. The method according to claim 1, characterized in that Disposing the thermosetting material on the front side of the flexible substrate further includes disposing the thermosetting material in a planar layout.

3. The method according to claim 2, characterized in that The planar layout includes three or more points that are not arranged on the same line.

4. The method according to claim 1, characterized in that: Disposing the thermosetting material on the front side of the flexible substrate further includes disposing the thermosetting material between two adjacent conductive patterns covering the solder bumps.

5. The method according to claim 1, characterized in that Disposing the thermosetting material on the front side of the flexible substrate further includes disposing the thermosetting material around the conductive pattern covering the solder bump.

6. The method according to claim 1, characterized in that Disposing the thermosetting material on the front side of the flexible substrate further includes disposing the thermosetting material in a layout aligned with the periphery of the electronic device.

7. The method according to claim 1, characterized in that The first temperature is higher than a curing temperature of the thermosetting material and lower than a melting point of the solder bump.

8. The method according to claim 1, characterized in that The electronic device is an antenna module.

9. A method for mounting an electronic device on a flexible substrate, characterized in that: include: Providing a flexible substrate, the front side of which has a conductive pattern; forming solder bumps on the conductive pattern; Disposing a thermosetting material on the bottom surface of the electronic device; bonding the bottom surface of the electronic device to the front surface of the flexible substrate via the solder bumps and the thermosetting material; heating the flexible substrate to a first temperature to cure the thermosetting material; as well as The flexible substrate is heated to a second temperature to reflow the solder bumps, the second temperature being higher than the first temperature.

10. An electronic package manufactured according to the method of any one of claims 1 to 9.

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