Manufacturing process of backlight module and backlight module

Abstract

The application discloses a manufacturing process of a backlight module and the backlight module. The manufacturing process of the backlight module comprises the following steps: S10, providing a substrate and an electronic device, and forming a first metal layer on a pad surface of the substrate and a second metal layer on a pin surface of the electronic device; S20, attaching the electronic device with the second metal layer on the pad surface of the substrate with the first metal layer; S30, providing a flexible film, and attaching the flexible film on a surface of the electronic device away from the substrate; S40, welding the first metal layer and the second metal layer, so that the pin of the electronic device is connected with the pad of the substrate; and S50, removing the flexible film to obtain the backlight module. The manufacturing process of the backlight module fixes the electronic device and the substrate together through the first metal layer and the second metal layer, avoids the problem of poor welding of the electronic device, and the flexible film plays a fixing role on the electronic device, so that the electronic device is prevented from deviating and other phenomena in the welding process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED, in particular to a manufacturing process of a backlight module and the backlight module. BACKGROUND

[0002] The COB (Chip on Board) backlight module is a kind of backlight module in which LED flip chips are fixed on a substrate by tin paste or other welding materials, and then the LED flip chips are encapsulated.

[0003] Currently, there are two welding methods for the LED chips of the COB backlight module. The first method is to print tin paste on the pads of the substrate, fix the LED chips on the substrate, and realize the welding of the LED chips and the substrate by reflowing. Due to the expansion and contraction of the substrate and the precision of the steel mesh, problems such as tin paste deviation, no tin, less tin or continuous tin are prone to occur, and the larger the size of the substrate is, the more obvious the influence is, which makes the LED chips prone to deviation, side turning or rotation, and leads to poor welding of the LED chips. Moreover, the amount of tin paste and the flatness of the tin paste are difficult to control during the printing of the tin paste, which directly affects the flatness of the welding of the LED chips.

[0004] The second method is to coat or print the flux on the substrate, plate tin on the electrodes of the LED chips, adhere the LED chips on the substrate, and realize the welding of the LED chips and the substrate by reflowing. Since the plated tin layer and the flux are both hard materials, and there is lack of adhesion between the plated tin layer and the flux, the LED chips are prone to deviation during reflowing due to the influence of chain vibration and circulating hot air in the oven, which leads to poor welding of the LED chips. Moreover, the use of flux spraying or dotting has low manufacturing efficiency, and the use of tin paste printing also has the problem of flux printing.

[0005] In addition, since both the first welding method and the second welding method use reflow welding, there are many residues after reflowing, which affects the light emitting effect of the LED, and for large size substrates, warping is prone to occur after reflowing, which affects the performance and assembly of the backlight module. SUMMARY

[0006] An object of the embodiments of the present application is to provide a welding process of a backlight module, which is simple to operate and effectively solves the problem of deviation of the LED chips during welding.

[0007] Another object of the embodiments of the present application is to provide a backlight module, which has a simple structure and can avoid the phenomenon of deviation or falling off of the LED chips caused by insufficient welding metal.

[0008] To achieve the above objects, the embodiments of the present application adopt the following technical solutions:

[0009] In a first aspect, a manufacturing process of a backlight module is provided, comprising the following steps:

[0010] In step S10, a substrate and an electronic device are provided, and a first metal layer is formed on a pad surface of the substrate and a second metal layer is formed on a pin surface of the electronic device;

[0011] In step S20, the electronic device with the second metal layer formed thereon is attached to the pad surface of the substrate with the first metal layer formed thereon;

[0012] In step S30, a flexible film is provided, and the flexible film is attached to a surface of the electronic device away from the substrate, so that the electronic device is fixed on the substrate;

[0013] In step S40, the first metal layer and the second metal layer are welded, so that the pin of the electronic device and the pad of the substrate are connected.

[0014] In step S50, the backlight module is manufactured after the flexible film is removed.

[0015] In an embodiment of the manufacturing process of the backlight module, the thickness of the first metal layer is 10-92 um, and the thickness of the second metal layer is 8-20 um.

[0016] In an embodiment of the manufacturing process of the backlight module, the material of the first metal layer and the second metal layer is tin metal or tin alloy.

[0017] In an embodiment of the manufacturing process of the backlight module, the electronic device comprises an LED chip and a driving element, and the pad of the substrate comprises an LED pad and a driving element pad;

[0018] The thickness of the first metal layer on the surface of the driving element pad is greater than the thickness of the first metal layer on the surface of the LED pad; and / or,

[0019] The thickness of the second metal layer on the pin surface of the driving element is greater than the thickness of the second metal layer on the pin surface of the LED chip.

[0020] As a preferred solution of the manufacturing process of the backlight module, when the LED chip and the driving element are located on the same side of the substrate, the LED chip is first attached to the LED pad surface, the flexible film is attached to the LED chip, the first metal layer of the LED pad surface and the second metal layer of the pin surface of the LED chip are welded, and then the flexible film attached to the LED chip is removed, and then the driving element is attached to the driving element pad surface, the flexible film is attached to the driving element, and the first metal layer of the driving element pad surface and the second metal layer of the pin surface of the driving element are welded.

[0021] As a preferred solution of the manufacturing process of the backlight module, the step S10 comprises:

[0022] Step S11, forming the first metal layer on the pad surface of the substrate by electroplating or chemical deposition;

[0023] Step S12, forming the second metal layer on the pin surface of the electronic device by electroplating or chemical deposition.

[0024] As a preferred solution of the manufacturing process of the backlight module, the step S40 comprises:

[0025] Step S41, providing a laser welding device, the laser emitted by the laser welding device melts the first metal layer and the second metal layer;

[0026] Step S42, after the first metal layer and the second metal layer are cooled and solidified, a welding layer is formed, and the pins of the electronic device and the pads of the substrate are connected through the welding layer.

[0027] As a preferred solution of the manufacturing process of the backlight module, the laser welding device comprises a bracket, the bracket is provided with a laser light source, a first support frame and a second support frame in sequence in the vertical direction, the first support frame comprises a light transmission plate, the flexible film is arranged on one side of the light transmission plate close to the second support frame, the substrate with the electronic device attached is placed on one side of the second support frame close to the first support frame, and the laser emitted by the laser light source transmits through the light transmission plate and the flexible film to melt the first metal layer and the second metal layer.

[0028] As a preferred solution of the manufacturing process of the backlight module, the second support frame comprises a plurality of telescopic rods, and the telescopic rods can selectively move the second support frame towards the first support frame.

[0029] As a preferred solution of the manufacturing process of the backlight module, the flexible film is a light-transmitting film, and the thickness of the flexible film is 100-1000 um.

[0030] In a second aspect, the application provides a backlight module manufactured by the manufacturing process of the backlight module, comprising a substrate and a plurality of electronic devices, wherein the substrate is provided with pads corresponding to the electronic devices, and the pins of the electronic devices are fixed on the pads by a soldering layer.

[0031] The electronic devices and the substrate are fixed together by the first metal layer and the second metal layer, so that the production process can be simplified, and the problem of poor die bonding of the electronic devices caused by the shift of the solder paste and the pads during the solder paste printing process can be effectively avoided; meanwhile, the sufficient amount of soldering metal can be ensured by the soldering of the first metal layer and the second metal layer, so that the electronic devices can be prevented from falling off due to insufficient soldering force; the flexible film is arranged during the soldering, so that the electronic devices can be fixed during the soldering process, and the problems of shift and overturn of the electronic devices can be avoided, thereby ensuring the consistency of the soldering of the electronic devices. BRIEF DESCRIPTION OF DRAWINGS

[0032] The application will be further described in detail below with reference to the drawings and embodiments.

[0033] Figure 1 The flowchart of the manufacturing process of the backlight module of the embodiment of the application.

[0034] Figure 2 The structure diagram of the electronic devices of the backlight module soldered by the laser soldering device of the embodiment of the application.

[0035] Figure 3 The structure diagram of the electronic devices attached to the substrate of the embodiment of the application.

[0036] Figure 4 The structure diagram of the backlight module of the embodiment of the application.

[0037] In the drawings:

[0038] 1, substrate; 11, first metal layer; 2, electronic device; 21, second metal layer; 22, LED chip; 23, driving element; 3, flexible film; 4, laser soldering device; 41, support; 42, laser light source; 43, first support frame; 431, light-transmitting plate; 44, second support frame; 441, telescopic rod; 5, soldering layer. DETAILED DESCRIPTION

[0039] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] In the description of the present application, unless explicitly defined and limited otherwise, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] In the present application, unless explicitly defined and limited otherwise, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0042] Reference Figure 1 As shown in the drawings, the present application provides a manufacturing process of a backlight module, comprising the following steps:

[0043] Step S10, providing a substrate 1 and an electronic device 2, forming a first metal layer 11 on the pad surface of the substrate 1 and forming a second metal layer 21 on the pin surface of the electronic device 2, respectively;

[0044] Step S20, bonding the electronic device 2 with the formed second metal layer 21 on the pad surface of the substrate 1 with the formed first metal layer 11;

[0045] Step S30, providing a flexible film 3, bonding the flexible film 3 on the surface of the electronic device 2 away from the substrate 1, so as to fix the electronic device 2 on the substrate 1;

[0046] Step S40, welding the first metal layer 11 and the second metal layer 21, so as to connect the pins of the electronic device 2 and the pads of the substrate 1;

[0047] Step S50, remove the flexible film 3 to obtain the backlight module.

[0048] In the embodiment of the present application, the electronic device 2 and the substrate 1 are welded together by the first metal layer 11 and the second metal layer 21, without the need of using the tin paste printing process, which can simplify the production process, effectively avoid the problem of poor die bonding of the electronic device 2 caused by tin paste deviation, no tin paste or less tin paste in the tin paste printing process, and ensure sufficient amount of welding metal to avoid the electronic device 2 from falling off due to insufficient welding force; the flexible film 3 is also provided during welding, which has a certain softness and elasticity, and can press the electronic device 2 when the flexible film 3 is attached to the upper surface of the electronic device 2 without causing damage to the electronic device 2. The flexible film 3 can play a fixing role in the welding process to avoid the electronic device 2 from deviating or turning over, thereby ensuring the consistency of the welding of the electronic device 2. The flexible film 3 can also be reused multiple times to avoid waste and increase manufacturing costs.

[0049] Specifically, in step S10, the first metal layer 11 is formed on the pad surface of the substrate 1 by electroplating or chemical deposition process including step S11;

[0050] Step S12, the second metal layer 21 is formed on the pin surface of the electronic device 2 by electroplating or chemical deposition process. The first metal layer 11 and the second metal layer 21 formed by chemical deposition or electroplating process have smooth surface, high consistency and uniformity, which can improve the flatness of the die bonding of the electronic device 2 and prevent the occurrence of floating core phenomenon, thereby improving the quality and consistency of the die bonding of the electronic device 2.

[0051] Specifically, referring to Figure 1 and Figure 2 In step S40, the laser welding device 4 is provided, and the laser emitted by the laser welding device 4 melts the first metal layer 11 and the second metal layer 21.

[0052] Step S42, after the first metal layer 11 and the second metal 12 are cooled and solidified, a welding layer 5 is formed, and the pins of the electronic device 2 and the pads of the substrate 1 are connected through the welding layer 5. The laser emitted by the laser welding device 4 passes through the flexible film 3 and is irradiated on the first metal layer 11 and the second metal layer 21, so that the first metal layer 11 and the second metal layer 21 are melted. After stopping the laser irradiation, the melted first metal layer 11 and the second metal layer 21 are cooled and solidified to form a welding layer 5, and the pins of the electronic device 2 and the pads of the substrate 1 are connected through the welding layer 5.

[0053] Specifically, the thickness of the first metal layer 11 on the pad of the substrate 1 is 10-92um, and the thickness of the second metal layer 21 on the pin of the electronic device 2 is 8-20um. The first metal layer 11 and the second metal layer 21 in this thickness range can ensure that the electronic device 2 and the substrate 1 are firmly fixed together, and the performance and appearance of the backlight module as a whole will not be affected due to too much molten first metal layer 11 and second metal layer 21.

[0054] Specifically, referring to Figure 3 As shown, the electronic device 2 includes an LED chip 22 and a driving element 23, the LED chip 22 is an LED flip chip, and the pad includes an LED pad and a driving element pad. Preferably, the thickness of the first metal layer 11 on the LED pad is 10-30um, and the thickness of the second metal layer 21 on the pin of the LED chip 22 is 8-20um, which can avoid the molten first metal layer 11 and second metal layer 21 overflowing onto the surface of the LED chip 22 to cause short circuit.

[0055] Further, the thickness of the first metal layer 11 of the driving element pad is greater than the thickness of the first metal layer 11 of the LED pad, and the thickness of the second metal layer 21 on the pin of the driving element 23 is greater than the thickness of the second metal layer 21 on the pin of the LED chip 22. Because the size of the driving element 23 is usually larger than the size of the LED chip 22, more solder metal layers are needed to ensure that the driving element 23 can be firmly fixed on the driving element pad.

[0056] In other embodiments, because the size of the driving element 23 is larger, the traditional printed tin paste soldering process can also be used to fix the driving element 23 on the pad.

[0057] Specifically, when the LED chip 22 and the driving element 23 are located on different sides of the substrate 1, the LED chip 22 can be first attached to the LED pad surface of the substrate 1, and then the flexible film 3 is attached to the LED chip 22 to fix the LED chip 22 on the LED pad. After the first metal layer 11 of the LED pad surface is welded with the second metal layer 21 of the pin surface of the LED chip 22, the flexible film 3 on the LED chip 22 is removed. Then, the driving element 23 is attached to the driving element pad of the substrate 1, and the flexible film 3 is attached to the driving element 23 to fix the driving element 23 on the driving element pad. Then, the first metal layer 11 of the driving element pad surface is welded with the second metal layer 21 of the pin surface of the driving element 23, and the flexible film 3 is removed after welding to obtain the backlight module. Alternatively, the driving element 23 can be first attached to the driving element pad of the substrate 1, and the flexible film 3 is attached to the driving element 23 to fix the driving element 23 on the driving element pad. Then, the first metal layer 11 of the driving element pad surface is welded with the second metal layer 21 of the pin surface of the driving element 23, and the flexible film 3 is removed after welding. Then, the LED chip 22 is attached to the LED pad surface of the substrate 1, and the flexible film 3 is attached to the LED chip 22 to fix the LED chip 22 on the LED pad. Then, the first metal layer 11 of the LED pad surface is welded with the second metal layer 21 of the pin surface of the LED chip 22, and the flexible film 3 on the LED chip 22 is removed after welding to obtain the backlight module. The welding sequence of the LED chip 22 and the driving element 23 can be determined according to actual conditions.

[0058] Specifically, when the LED chip 22 and the driving element 23 are located on the same side of the substrate 1, the size of the driving element 23 is larger than that of the LED chip 22, resulting in different heights of the LED chip 22 and the driving element 23 attached to the substrate 1. The flexible film 3 cannot be simultaneously attached to the LED chip 22 and the driving element 23. Therefore, the LED chip 22 is first attached to the LED pad surface of the substrate 1, and then the flexible film 3 is attached to the LED chip 22 to fix the LED chip 22 on the LED pad. After the first metal layer 11 of the LED pad surface is welded with the second metal layer 21 of the pin surface of the LED chip 22, the flexible film 3 on the LED chip 22 is removed. Then, the driving element 23 is attached to the driving element pad of the substrate 1, and the flexible film 3 is attached to the driving element 23 to fix the driving element 23 on the driving element pad. Then, the first metal layer 11 of the driving element pad surface is welded with the second metal layer 21 of the pin surface of the driving element 23, and the flexible film 3 is removed after welding to obtain the backlight module. By welding the LED chip 22 first and then welding the driving element 23, the flexible film 3 can play a fixing role during the welding of the LED chip 22 and the driving element 23.

[0059] Specifically, the first metal layer 11 and the second metal layer 21 are made of tin metal or tin alloy. Tin has a low melting point and can easily melt rapidly under laser irradiation.

[0060] Specifically, the flexible film is a light-transmitting film, and the thickness of the flexible film 3 is 100-1000 μm. If the thickness of the flexible film 3 is too large, the laser will not be able to penetrate the flexible film 3 easily, making it difficult to melt the first metal layer 11 and the second metal layer 21; if the thickness of the flexible film 3 is too small, the flexible film 3 will not be able to hold the electronic device 2 down, which may cause the electronic device 2 to shift during welding.

[0061] Specifically, refer to Figure 2 As shown, the laser welding device 4 includes a bracket 41. Inside the bracket 41, a laser source 42, a first support frame 43, and a second support frame 44 are arranged in sequence along the vertical direction. The first support frame 43 includes a light-transmitting plate 431. A flexible film 3 is disposed on the side of the light-transmitting plate 431 near the second support frame 44. A substrate 1 with electronic devices 2 attached is placed on the side of the second support frame 44 near the first support frame 43. The flexible film 3 presses down on the electronic devices 2 on the substrate 1. The laser emitted by the laser source 42 can pass through the light-transmitting plate 431 and the flexible film 3 to heat melt the first metal layer 11 and the second metal layer 21.

[0062] Understandably, the laser light source 42, the light-transmitting plate 431, the flexible film 3, and the substrate 1 on which the electronic device 2 is placed are arranged vertically in sequence. The light-transmitting plate 431 is made of transparent glass or acrylic plexiglass, etc. The light-transmitting plate 431 and the flexible film 3 do not absorb the laser. The laser can pass through the light-transmitting plate 431 and the flexible film 3 to irradiate the first metal layer 11 and the second metal layer 21. After absorbing the laser, the first metal layer 11 and the second metal layer 21 melt and bond together. After cooling, they form a welding layer 5, completing the welding of the electronic device 2. By replacing the traditional reflow soldering with the laser welding device 4, on the one hand, the electronic device 2 can be effectively fixed on the pads of the substrate 1 during the die bonding operation, avoiding the displacement of the electronic device 2 during the welding process; on the other hand, it can avoid the board warping that occurs on the substrate 1 during reflow soldering, thereby affecting product performance and downstream assembly problems.

[0063] Furthermore, the second support frame 44 includes a plurality of telescopic rods 441, which can selectively move the second support frame 44 toward the first support frame 43. The second support frame 44 is height-adjustable, which facilitates the bonding of the substrate 1 on which the electronic device 2 is placed with the flexible film 3.

[0064] In practice, taking the welding of LED chip 22 as an example, the manufacturing process of the backlight module includes the following steps:

[0065] Step S100, providing a substrate 1 and an LED chip 22, forming a tin plating layer on the pads of the substrate 1 by a chemical tin plating process, and forming a tin plating layer on the pins of the LED chip 22 by an electroplating process. Wherein the substrate 1 can be a PCB board, a BT board, an aluminum substrate or an FPB board, the thickness of the tin plating layer is 20um, and the thickness of the tin plating layer is 10um;

[0066] Step S200, using a die bonder to place the LED chip 22 on the pads of the substrate 1;

[0067] Step S300, placing the substrate 1 with the LED chip 22 on the second support frame 44, fixing the flexible film 3 on the light-transmitting plate 431 on the side close to the second support frame 44, and driving the second support frame 44 to rise so that the upper surface of the LED chip 22 is attached to the flexible film 3;

[0068] Step S400, starting the laser welding device 4, the laser emitted by the laser light source 42 transmits through the light-transmitting plate 431 and the flexible film 3 and is irradiated on the tin plating layer and the tin plating layer, and the tin plating layer and the tin plating layer are fixed together after melting, the laser light source 42 is turned off, and the welding is completed after cooling;

[0069] Step S500, driving the second support frame 44 to descend, thereby removing the flexible film 3 to obtain a backlight module.

[0070] Comparative example:

[0071] Step S101, providing an LED chip 22, and forming a tin plating layer on the pins of the LED chip 22, wherein the thickness of the tin plating layer is 10um;

[0072] Step S201, providing a substrate 1, printing a flux on the pads of the substrate 1, and using a die bonder to place the LED chip 22 with the tin plating layer formed thereon on the pads of the substrate 1 with the flux printed thereon;

[0073] Step S301, placing the substrate 1 with the LED chip 22 placed thereon into a reflow oven to obtain a backlight module by a reflow welding process.

[0074] Test: A chip thrust machine is used to test the welding thrust of the LED chip 22 of the backlight module obtained by the manufacturing process of the backlight module of the embodiment and the manufacturing process of the backlight module of the comparative example, and the test results are shown in Tables 1 and 2.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] The backlight module manufacturing process of the present application can solve the problem of LED chip 22 deviation caused by external force and the problem of the tin plating layer of the tin plated LED chip 22 being unable to be thickened, thereby improving the die bonding thrust level of the LED chip 22.

[0080] Referring to Figure 4 The present application also provides a backlight module manufactured by the above backlight module manufacturing process, comprising a substrate 1 and a plurality of electronic devices 2, the substrate 1 is provided with pads corresponding to the electronic devices 2, and the pins of the electronic devices 2 are fixed on the pads through the soldering layer 5. The backlight module manufactured by the above manufacturing process is not prone to the problems of die bonding failure of the electronic devices 2 and falling off of the electronic devices 2, and the quality of the backlight module is high.

[0081] In the description herein, it should be understood that the terms "upper", "lower", and the like positional or location relationships are based on the positional or location relationships shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0082] In the description of the present application, the description of the terms "one embodiment" and the like means that the specific features, structures, materials or characteristics of the embodiment are contained in at least one embodiment or example of the present application. In the present description, the illustrative description of the above terms does not necessarily refer to the same embodiment.

[0083] In addition, it should be understood that although the present application is described in terms of embodiments, each embodiment does not necessarily contain only one independent technical solution, and the description of the present application is only for the sake of clarity, and those skilled in the art should consider the present application as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0084] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for the purpose of explaining the principles of the present application, and cannot be interpreted in any way as a limitation on the scope of protection of the present application. Based on the explanations herein, those skilled in the art can think of other specific embodiments of the present application without creative labor, and these embodiments will fall within the scope of protection of the present application.

Claims

1. A manufacturing process of a backlight module, characterized in that, The method comprises the following steps: Step S10, providing a substrate and an electronic device, forming a first metal layer on a pad surface of the substrate and forming a second metal layer on a pin surface of the electronic device; Step S20, adhering the electronic device with the second metal layer to the pad surface of the substrate with the first metal layer; Step S30, providing a flexible film, adhering the flexible film to a surface of the electronic device away from the substrate to fix the electronic device on the substrate; Step S40, welding the first metal layer and the second metal layer to connect the pins of the electronic device and the pads of the substrate; Step S50, removing the flexible film to obtain a backlight module; The step S40 comprises: Step S41, providing a laser welding device, the laser welding device comprises a support, a laser light source, a first support frame and a second support frame are sequentially arranged in the support in a vertical direction, the first support frame comprises a light-transmitting plate, the flexible film is arranged on a side of the light-transmitting plate close to the second support frame, the substrate with the electronic device adhered is arranged on a side of the second support frame close to the first support frame, and the laser light emitted by the laser light source penetrates the light-transmitting plate and the flexible film to irradiate on the first metal layer and the second metal layer to melt the first metal layer and the second metal layer; Step S42, after the first metal layer and the second metal layer are cooled and solidified, a welding layer is formed, and the pins of the electronic device and the pads of the substrate are connected through the welding layer.

2. The manufacturing process of the backlight module according to claim 1, wherein, The thickness of the first metal layer is 10-92 um, and the thickness of the second metal layer is 8-20 um.

3. The manufacturing process of the backlight module according to claim 1, wherein, The materials of the first metal layer and the second metal layer are tin metal or tin alloy.

4. The manufacturing process of the backlight module according to claim 1, wherein, The electronic device comprises an LED chip and a driving element, and the pads of the substrate comprise LED pads and driving element pads; The thickness of the first metal layer on the surface of the driving element pad is greater than the thickness of the first metal layer on the surface of the LED pad; and / or The thickness of the second metal layer on the pin surface of the driving element is greater than the thickness of the second metal layer on the pin surface of the LED chip.

5. The manufacturing process of the backlight module according to claim 4, wherein, When the LED chip and the driving element are located on the same side of the substrate, the LED chip is first adhered to the surface of the LED pad, the flexible film is adhered to the LED chip, the first metal layer on the surface of the LED pad and the second metal layer on the pin surface of the LED chip are welded, the flexible film adhered to the LED chip is removed, the driving element is then adhered to the surface of the driving element pad, the flexible film is adhered to the driving element, and the first metal layer on the surface of the driving element pad and the second metal layer on the pin surface of the driving element are welded, and the flexible film is removed.

6. The manufacturing process of the backlight module according to claim 1, wherein, The step S10 comprises: Step S11, forming the first metal layer on the pad surface of the substrate by electroplating or chemical deposition process; Step S12, forming the second metal layer on the pin surface of the electronic device by electroplating or chemical deposition process.

7. The manufacturing process of the backlight module according to claim 1, characterized in that, The second support frame comprises a plurality of telescopic rods capable of selectively moving the second support frame towards the first support frame.

8. The manufacturing process of the backlight module according to claim 1, characterized in that, The flexible film is a light-transmitting film, and the thickness of the flexible film is 100-1000 um.

9. A backlight module, characterized in that, The manufacturing process of the backlight module is made by using the manufacturing process of any one of claims 1-8, and the backlight module comprises a substrate and a plurality of electronic devices, and the substrate is provided with pads corresponding to the electronic devices, and the pins of the electronic devices are fixed on the pads through a welding layer.

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