Chip welding method and display module

Abstract

The present invention discloses a chip welding method and a display module using the welding method. Before welding a second chip, it is first determined whether a laser spot will irradiate an irradiation area of ​​the laser spot on a substrate when welding a first chip, wherein the first chip is a chip welded to the substrate before the second chip; if not, the second chip is welded to the substrate; if so, the second chip is skipped and a third chip whose irradiation area is not irradiated by the laser spot is welded first, thereby avoiding damage to the substrate due to excessively high temperature in a local area of ​​the substrate caused by the overlap of the irradiation areas of the two welding spots when welding the chips.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a chip welding method and a display module. Background Art

[0002] Laser welding is highly efficient and precise, but the laser spot may be larger than the chip. When laser welding chips, the laser spot will irradiate the local area of ​​the substrate that is not blocked by the chip. If a local area of ​​the substrate is irradiated continuously, the temperature of the local area of ​​the substrate will be too high. For example, when the local area is irradiated for the first time, the temperature of the local area is 500°C. If the local area is irradiated again immediately afterwards, the temperature of the local area may rise to 1000°C, which can easily cause damage to the substrate. Summary of the invention

[0003] The object of the present invention is to provide a chip welding method and a display module using the welding method to weld chips, so as to prevent damage to the substrate caused by excessively high temperature in a local area of ​​the substrate.

[0004] To achieve the above-mentioned purpose, the present invention provides a chip welding method for welding a plurality of chips on a substrate. The chip welding method, before welding the second chip, determines whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, and the first chip is the chip welded on the substrate before the second chip; if so, skip the second chip and first weld the third chip in the irradiation area where the laser spot will not irradiate.

[0005] In some embodiments, the step of determining whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip includes:

[0006] Obtaining the laser spot size, chip size, and arrangement positions of the plurality of chips on the substrate;

[0007] Obtaining the spacing between the chips according to the arrangement positions of the plurality of chips on the substrate;

[0008] According to the spot size, the chip size and the spacing size, it is determined whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when the first chip is welded.

[0009] In some embodiments, the third chip is the chip that is closest to the first chip among the plurality of chips except the second chip, and the laser spot will not irradiate the irradiation area.

[0010] In some embodiments, if it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, the judgment result is yes, and before welding the second chip to the substrate, a cooling device is used to cool the irradiation area.

[0011] In some embodiments, if it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, if the judgment result is yes, the actual temperature of the irradiation area is obtained, and when the actual temperature is reduced to a preset temperature or below the preset temperature, the second chip is welded to the substrate.

[0012] In some embodiments, if it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, if the determination result is yes, the second chip is welded to the substrate after a preset time delay.

[0013] In some embodiments, the preset time is a time that can reduce the actual temperature of the irradiation area to a preset temperature or below the preset temperature.

[0014] In some embodiments, the spot of the first welding laser will not irradiate the third chip in the irradiation area, including: determining whether there is a chip to be welded on the extension line of the straight line where the first chip and the second chip are located; if so, selecting the third chip from the chips to be welded, and welding the third chip to the substrate.

[0015] To achieve the above object, the present invention provides a display module, which includes a substrate and a plurality of chips welded on the substrate, wherein the plurality of chips are welded on the substrate using the chip welding method as described above.

[0016] Before welding a chip to be welded later, the present invention first determines whether the laser spot will irradiate the irradiation area of ​​the light spot on the substrate when welding the previous chip. If it will not irradiate the irradiation area, the chip to be welded later is welded to the substrate. If it will irradiate the irradiation area, the chip to be welded later is skipped, and other chips in the irradiation area will not be irradiated by the laser spot. This can avoid excessive temperature in a local area of ​​the substrate due to overlap of the irradiation areas of the two welding spots when welding the chips, thereby avoiding damage to the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of a chip bonding method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to explain the content, structural features, achieved purposes and effects of the present invention in detail, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The display module generally includes a substrate and a plurality of light-emitting chips arranged on the substrate. During the manufacturing process of the display module, the electrodes of the plurality of light-emitting chips need to be soldered to the corresponding pads on the substrate. In addition to the pads, the substrate is also provided with connecting circuits and some necessary electronic components to carry the plurality of light-emitting chips through the substrate, provide driving power to the plurality of light-emitting chips, and control the opening and closing of the plurality of light-emitting chips.

[0020] The present invention provides a chip welding method. Before welding a chip to be welded later, it is first determined whether a laser spot will irradiate an irradiation area of ​​the laser spot on a substrate when welding a previous chip. If the laser spot will not irradiate the irradiation area, the chip to be welded later is welded to the substrate. If the laser spot will irradiate the irradiation area, the chip to be welded later is skipped, and other chips in the irradiation area will not be irradiated by the laser spot. This can avoid damage to the substrate due to excessive temperature in a local area of ​​the substrate caused by the overlap of the irradiation areas of the two welding spots when welding the chips.

[0021] The chip bonding method of the present invention is described in detail below by taking a specific embodiment as an example and combining with the accompanying drawings.

[0022] See also Figure 1 In a chip welding method according to an embodiment of the present invention, before welding a second chip, it is determined whether a laser spot will irradiate an irradiation area of ​​the laser spot on a substrate when welding a first chip, wherein the first chip is a chip welded to the substrate before the second chip;

[0023] If not, soldering the second chip to the substrate;

[0024] If so, skip the second chip and first weld the third chip where the laser spot will not irradiate the irradiation area.

[0025] It can be understood that the first chip, the second chip, and the third chip do not refer to a specific chip. The first chip can be any chip that is previously welded to the substrate before the second chip is welded to the substrate. It is not limited to the first chip welded to the substrate, nor is it limited to a chip arranged at a certain position on the substrate. The third chip can be any one or more chips other than the first chip and the second chip that have not yet been welded to the substrate, and during welding, the laser spot will not irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip.

[0026] It can be understood that the first chip, the second chip, and the third chip do not specifically refer to one chip, but may also refer to multiple chips. When the laser is a linear light source or a surface light source, it may be a series of chips, and the laser welds the series of chips at the same time.

[0027] Before welding the third chip, determine whether there is a chip to be welded on the extension line of the straight line where the first chip and the second chip are located; if so, select the third chip from the chips to be welded, so that the welding equipment can move along a straight line, simplifying the movement process. After welding the third chip, you can directly return to weld the second chip, or you can return to weld the second chip after welding the fourth chip and the fifth chip. Among them, the fourth chip can be any one or more chips other than the first chip, the second chip, and the third chip, which have not been welded to the substrate, and the laser spot will not irradiate the irradiation area of ​​the spot on the substrate when welding the third chip during welding; the fifth chip can be any one or more chips other than the first chip, the second chip, the third chip, and the fourth chip, which have not been welded to the substrate, and the laser spot will not irradiate the irradiation area of ​​the spot on the substrate when welding the fourth chip during welding. The fourth chip and the fifth chip can also be on the extension line of the straight line where the second chip and the third chip are located.

[0028] In one embodiment, the third chip is the chip that is closest to the first chip among the plurality of chips except the second chip, and the laser spot will not irradiate the irradiation area. In two adjacent welding processes, the irradiation areas of the light spot do not overlap but are closest, which can avoid the laser head used to emit laser from moving too long during the two adjacent welding processes, and can improve the chip welding efficiency.

[0029] In one embodiment, the following method is used to determine whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when welding the first chip: first, the laser spot size, chip size and the arrangement position of several chips on the substrate are obtained; then, the spacing size between the chips is obtained according to the arrangement position of the several chips on the substrate; and then, based on the spot size, chip size and spacing size, it is determined whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when welding the first chip.

[0030] In one embodiment, when judging whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when welding the first chip, the judgment result is that the second chip is skipped and the third chip is welded before welding; or, after welding the third chip and before welding the second chip; or, while welding the third chip, the irradiation area is cooled by a cooling device. In this way, the temperature drop of the irradiation area can be accelerated, the time for waiting for the irradiation area to cool down to weld the second chip can be reduced, and the moving distance of the laser head can be shortened when the laser spots of two consecutive weldings do not overlap.

[0031] Among them, a cooling device may be integrated in the laser head, such as a fan is provided in the laser head to blow cold air to the irradiated area for cooling, or an additional cooling device independent of the laser head may be provided, for example, a movable fan is provided, and cooling is achieved by moving the fan to a position corresponding to the irradiated area and blowing cold air toward the irradiated area.

[0032] In one embodiment, if it is determined whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when welding the first chip, and the judgment result is yes, the actual temperature of the irradiation area of ​​the spot on the substrate after welding the first chip is also obtained, and the second chip is welded to the substrate after the actual temperature drops to a preset temperature or below the preset temperature. By obtaining the actual temperature of the irradiation area and welding the second chip after the actual temperature of the irradiation area drops to a preset temperature or below the preset temperature, it is possible to avoid the laser spot irradiating the irradiation area of ​​the spot on the substrate when welding the first chip when welding the second chip, which may cause damage to the substrate due to excessively high temperature of the irradiation area.

[0033] In one embodiment, if it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, the determination result is yes, and the second chip is welded to the substrate after a preset delay time.

[0034] The preset time is the time that can reduce the actual temperature of the irradiated area of ​​the laser spot on the substrate to the preset temperature or below the preset temperature when welding the first chip. For example, when welding the first chip, due to the thermal effect of the laser spot, the temperature of the irradiated area on the substrate corresponding to the laser spot will rise to 500°C. If no auxiliary cooling measures are taken, the actual temperature of the irradiated area will usually drop to the preset temperature, such as 200°C, after 3 minutes through natural cooling. Then, the preset time can be set to at least 3 minutes; if the irradiated area on the substrate is cooled by a cooling device, the actual temperature of the irradiated area will usually drop to the preset temperature, such as 200°C, after 1 minute. Then, the preset time can be set to at least 1 minute. During the cooling period, other chips can be welded synchronously.

[0035] By estimating that after the preset time, the actual temperature of the irradiated area of ​​the light spot on the substrate when welding the first chip will drop to the preset temperature or below the preset temperature, the welding is controlled according to the time, and the chip welding control is simpler and easier to implement.

[0036] In summary, before welding the chip to be welded later, the present invention first determines whether the laser spot will irradiate the irradiation area of ​​the light spot on the substrate when welding the previous chip. If it will not irradiate the irradiation area, then weld the chip to be welded later to the substrate. If it will irradiate the irradiation area, then skip the chip to be welded later and weld other chips in the irradiation area that will not be irradiated by the laser spot. This can avoid damage to the substrate due to excessive temperature in a local area of ​​the substrate caused by the overlap of the irradiation areas of the two welding spots when welding the chips.

[0037] The above disclosure is only a preferred embodiment of the present invention, which cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are all within the scope of the present invention.

Claims

1. A chip welding method for welding a plurality of chips on a substrate, characterized in that: Before laser welding the second chip, determine whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, the first chip being a chip welded on the substrate before the second chip; If not, soldering the second chip to the substrate; If yes, skip the second chip and first use the laser to weld a third chip whose laser spot will not irradiate the irradiation area. The third chip is the chip closest to the first chip among the plurality of chips except the second chip, and the laser spot will not irradiate the irradiation area. The step of judging whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip includes: Obtaining the laser spot size, chip size, and arrangement positions of the plurality of chips on the substrate; Obtaining the spacing between the chips according to the arrangement positions of the plurality of chips on the substrate; According to the spot size, the chip size and the spacing size, it is determined whether the laser spot will irradiate the irradiation area of ​​the spot on the substrate when the first chip is welded.

2. The chip bonding method according to claim 1, characterized in that: If it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, the judgment result is yes, and before welding the second chip to the substrate, a cooling device is used to cool the irradiation area.

3. The chip bonding method according to claim 2, characterized in that: If it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, if the judgment result is yes, the actual temperature of the irradiation area is obtained, and when the actual temperature is reduced to a preset temperature or below the preset temperature, the second chip is welded to the substrate.

4. The chip bonding method according to claim 1, characterized in that: If it is determined whether the laser spot will irradiate the irradiation area of ​​the laser spot on the substrate when welding the first chip, if the result of the determination is yes, the second chip is welded to the substrate after a preset time delay.

5. The chip bonding method according to claim 4, characterized in that: The preset time is the time required for the actual temperature of the irradiated area to drop to a preset temperature or below the preset temperature.

6. The chip bonding method according to claim 1, characterized in that: The first step of using the laser to weld the third chip without irradiating the laser spot to the irradiation area includes: Determine whether there is a chip to be welded on the extension line of the straight line where the first chip and the second chip are located; If yes, the third chip is selected from the chips to be welded, and the third chip is welded to the substrate.

7. A display module, comprising a substrate and a plurality of chips soldered on the substrate, characterized in that: The plurality of chips are welded on the substrate using the chip welding method according to any one of claims 1 to 6.

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