Keyboard backlight module manufacturing method based on pre-packaged light emitting chip

Abstract

The application relates to the field of keyboard manufacturing methods, in particular to a keyboard backlight module manufacturing method based on pre-packaged light-emitting chips. The method comprises the following steps: S1, pre-packaging light-emitting chips to form light-emitting units; S2, attaching the light-emitting units to a circuit board; S3, welding and fixing the pins of the light-emitting units to first pads on the circuit board through reflow soldering; and S4, performing secondary packaging coating on the top, side, bottom soldering point connection area and the peripheral circuit board area of the light-emitting units after welding. By adopting the pre-packaged flip chip light-emitting unit without a support and gold wire, the body volume and height of the light source part are greatly reduced. Meanwhile, a lamp groove is directly arranged on a light guide sheet to accommodate the light-emitting unit, so that the light source can be embedded in the light guide sheet, the overall structure is extremely compact, and the ultrathinning of the keyboard backlight module is finally realized, thereby meeting the pursuit of extreme thinness of modern electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of keyboard manufacturing methods, and in particular to a method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip. Background Technology

[0002] In existing technologies, keyboard backlight modules typically employ surface mount technology, directly mounting traditional LED chips onto the circuit board. This traditional approach suffers from the following drawbacks: Large structural thickness, limiting thinner designs: Traditional LED chips contain a support structure for the chip and are connected to the chip's electrodes using wire bonding (e.g., gold wire). This structure results in a large package size and height for the LED chip itself, hindering the achievement of ultra-thin keyboard designs. Low reliability and failure risks: "Dead LED" risk: When the keyboard is subjected to external impact or bending, the fragile gold wire connection structure inside the LED chip is prone to breakage, leading to LED failure, also known as a "dead LED." "LED detachment" risk: Under poor soldering processes or stress, the LED chip itself can easily peel off from the circuit board, resulting in "LED detachment." In summary, existing keyboard backlight modules based on traditional LED packaging solutions have shown significant shortcomings in meeting the demands of high reliability, high shock resistance, and ultra-thin designs in modern consumer electronics devices. Summary of the Invention

[0003] To address the shortcomings of the prior art described in the background section, this invention provides a method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip. This invention significantly reduces the volume and height of the light source by employing a pre-packaged, frameless, and wire-free flip-chip light-emitting unit. Simultaneously, a light groove is directly formed on the light guide plate to accommodate the light-emitting unit, allowing the light source to be embedded within the light guide plate. This results in an extremely compact overall structure, ultimately achieving an ultra-thin keyboard backlight module that meets the demands of modern electronic devices for extreme thinness and lightness.

[0004] The light-emitting chip inside the light-emitting unit adopts a flip-chip structure, directly connecting to the second pad of the substrate via electrodes, eliminating the need for fragile gold wires. Simultaneously, the encapsulation layer provides complete protection for the chip. This structure fundamentally eliminates the risk of gold wire breakage due to bending or impact, significantly improving mechanical stability and shock resistance.

[0005] The light-emitting unit is directly soldered to the first pad of the circuit board through its substrate pins and is further wrapped and fixed by the encapsulation layer. This double fixing structure is very strong and effectively avoids the problem of traditional SMT LEDs being easily peeled off from the circuit board.

[0006] The texture or dots on the surface of the light guide plate can efficiently guide and diffuse the light emitted by the light-emitting unit. The light shield prevents light from leaking from the sides, ensuring that the light is concentrated and evenly transmitted from the keycap area, thereby improving the visual effect of the keyboard backlight and the user experience.

[0007] By employing advanced processes such as mass transfer, integral molding, optical inspection and grading, and intelligent sorting, the light-emitting units are manufactured and screened with high efficiency and precision, laying the foundation for the subsequent assembly of backlight modules with uniform optical performance and consistent quality.

[0008] The technical solution adopted by this invention to solve its technical problem is: A method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip includes the following steps: S1. Pre-package the light-emitting chip to form a light-emitting unit; S2. Mount the light-emitting unit onto the circuit board; S3. The pins of the light-emitting unit are soldered and fixed to the first pad on the circuit board by reflow soldering; S4. Perform secondary encapsulation coating on the top, side, and bottom solder joint connection areas of the light-emitting unit and its surrounding circuit board area after welding. S5. Curing the adhesive layer applied for secondary encapsulation to form an encapsulation layer; S6. A light guide sheet with a lamp groove is laid on the circuit board so that the light-emitting unit and the encapsulation layer are accommodated in the lamp groove. S7. Lay the light-shielding sheet on the light guide sheet and connect the edge of the light-shielding sheet to the edge of the circuit board; S8. Inspect the assembled backlight module.

[0009] Specifically, step S1 includes: S11. Prepare a substrate, form fine conductive lines and a second pad for carrying the light-emitting chip on the front side of the substrate, form pins for external connection on the back side of the substrate, and provide metallized through holes in the substrate to realize the electrical connection between the second pad and the pins. S12. Using mass transfer technology, the flip-chip is transferred and bonded to the second pad on the front side of the substrate to form a chip array. S13. The light-emitting chip array is integrally molded and encapsulated to form an encapsulating colloid layer covering all the light-emitting chips, thereby obtaining a light-emitting unit array; S14. Perform optical detection on the light-emitting unit array and generate a graded level mapping spectrum based on the detection results; S15. According to the graded level mapping spectrum, the light-emitting unit array is precisely cut to separate it into independent individual light-emitting units; S16. Based on the graded level mapping map, sort and classify the individual light-emitting units.

[0010] Specifically, in step S11, the substrate is selected from rigid substrates composed of glass substrates, ceramic substrates, and resin-based composite material substrates, or flexible circuit boards composed of polyimide-based or liquid crystal polymer-based substrates; the line width and line spacing of the micro-conductive lines are both between 10μm and 100μm; and the diameter of the metallized via is between 5μm and 100μm.

[0011] Specifically, when the substrate is a glass substrate, the diameter of the metallized via is 5μm to 50μm, and a hole-in-the-pan structure is formed by laser drilling and electroplating filling processes.

[0012] Specifically, in step S12, the electrodes of the light-emitting chip are connected to the second pad of the substrate through a reflow soldering process with a peak temperature of 200°C to 300°C.

[0013] Specifically, in step S13, epoxy resin or silicone is used for molding and encapsulation to form the encapsulating adhesive layer.

[0014] Specifically, in step S15, the cutting path avoids the effective area of ​​the light-emitting chip by at least 20 μm; and based on the graded level mapping map, the area determined to be unqualified can be skipped during cutting.

[0015] Specifically, the execution order of steps S14, S15, and S16 can be adjusted as follows: first, step S15 is executed to cut and separate the components; then, step S14 is executed to perform optical detection and grading on the individual light-emitting units; and finally, step S16 is executed to sort the components based on the grading results.

[0016] Specifically, in step S2, before mounting the light-emitting unit onto the first pad of the circuit board, die-bonding solder is applied to the first pad of the circuit board.

[0017] The beneficial effects of this invention are as follows: This invention provides a method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip. By employing a pre-packaged, frameless, and wire-free flip-chip light-emitting unit, this invention significantly reduces the volume and height of the light source component. Simultaneously, a light groove is directly formed on the light guide sheet to accommodate the light-emitting unit, allowing the light source to be embedded within the light guide sheet. The overall structure is extremely compact, ultimately achieving an ultra-thin keyboard backlight module that meets the pursuit of extreme thinness in modern electronic devices.

[0018] The light-emitting chip inside the light-emitting unit adopts a flip-chip structure, directly connecting to the second pad of the substrate via electrodes, eliminating the need for fragile gold wires. Simultaneously, the encapsulation layer provides complete protection for the chip. This structure fundamentally eliminates the risk of gold wire breakage due to bending or impact, significantly improving mechanical stability and shock resistance.

[0019] The light-emitting unit is directly soldered to the first pad of the circuit board through its substrate pins and is further wrapped and fixed by the encapsulation layer. This double fixing structure is very strong and effectively avoids the problem of traditional SMT LEDs being easily peeled off from the circuit board.

[0020] The texture or dots on the surface of the light guide plate can efficiently guide and diffuse the light emitted by the light-emitting unit. The light shield prevents light from leaking from the sides, ensuring that the light is concentrated and evenly transmitted from the keycap area, thereby improving the visual effect of the keyboard backlight and the user experience.

[0021] By employing advanced processes such as mass transfer, integral molding, optical inspection and grading, and intelligent sorting, the light-emitting units are manufactured and screened with high efficiency and precision, laying the foundation for the subsequent assembly of backlight modules with uniform optical performance and consistent quality. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the light-emitting unit of the present invention; Figure 3 This is a schematic diagram of the circuit board, light guide sheet, and light shield of the present invention; In the figure: 1. Circuit board, 2. Light-emitting unit, 3. Encapsulation layer, 4. Light guide plate, 5. Light shield, 11. First pad, 21. Light-emitting chip, 22. Substrate, 24. Pin, 25. Second pad, 27. Electrode, 28. Encapsulation colloid layer, 29. Via. Detailed Implementation

[0024] Combined with appendix Figure 1 and attached Figure 2 As shown, a method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip includes the following steps: S1. Pre-package the light-emitting chip 21 to form the light-emitting unit 2; S2. The light-emitting unit 2 is mounted on the circuit board 1. Before mounting the light-emitting unit 2 onto the first pad 11 of the circuit board, die bond solder is applied to the first pad 11 of the circuit board.

[0025] S3. The pins 24 of the light-emitting unit 2 are soldered and fixed to the first pad 11 on the circuit board 1 by reflow soldering. S4. Perform secondary encapsulation coating on the top, side, and bottom solder joint connection areas of the light-emitting unit 2 and the surrounding circuit board 1 area after welding. S5. Cure the adhesive layer coated by the secondary encapsulation to form the encapsulation layer 3; S6. The light guide sheet 4 with the lamp groove 41 is laid on the circuit board 1, so that the light-emitting unit 2 and the encapsulation layer 3 are accommodated in the lamp groove 41. S7. The light-shielding sheet 5 is laid on the light guide sheet 4, and the edge of the light-shielding sheet 5 is connected to the edge of the circuit board 1; S8. Inspect the assembled backlight module.

[0026] Step S1 includes: S11. Prepare substrate 22, form fine conductive lines and a second pad 25 for carrying light-emitting chip 21 on the front side of substrate 22, form pins 24 for external connection on the back side of substrate 22, and provide metallized through holes in substrate 22 to realize electrical connection between the second pad 25 and the pins 24. S12. Using mass transfer technology, the flip-chip 21 is transferred and bonded to the second pad 25 on the front side of the substrate 22 to form a light-emitting chip array; the electrodes 27 of the light-emitting chip 21 are connected to the second pad 25 of the substrate through a reflow soldering process with a peak temperature of 200°C to 300°C.

[0027] S13. The light-emitting chip array is integrally molded and encapsulated to form an encapsulation colloid layer 28 covering all light-emitting chips 21, thereby obtaining a light-emitting unit array; epoxy resin or silicone is used for molding and encapsulation to form the encapsulation colloid layer 28.

[0028] S14. Perform optical detection on the light-emitting unit array and generate a graded level mapping spectrum based on the detection results; S15. According to the graded level mapping map, the light-emitting unit array is precisely cut to separate it into independent individual light-emitting units 2; the cutting path avoids the effective area of ​​the light-emitting chip 21 by at least 20μm; and the cutting operation can be skipped for areas determined to be unqualified based on the graded level mapping map.

[0029] S16. Based on the graded level mapping map, sort and classify the individual light-emitting units 2.

[0030] In step S11, the substrate 22 is selected from rigid substrates composed of glass substrates, ceramic substrates, and resin-based composite material substrates, or flexible circuit boards composed of polyimide-based or liquid crystal polymer-based substrates; the line width and line spacing of the micro-conductive lines are both between 10 μm and 100 μm; the diameter of the metallized vias is between 5 μm and 100 μm. When the substrate 22 is a glass substrate, the diameter of the metallized vias 29 is between 5 μm and 50 μm, and a hole-in-a-disk structure is formed by laser drilling and electroplating filling processes.

[0031] The execution order of steps S14, S15, and S16 can be adjusted as follows: first, step S15 is executed to cut and separate the components; then, step S14 is executed to perform optical detection and grading on the individual light-emitting units 2; and finally, step S16 is executed to sort the components based on the grading results.

[0032] The keyboard backlight module provided in this embodiment mainly includes, from bottom to top: a circuit board 1, a light-emitting unit 2, an encapsulation layer 3, a light guide sheet 4, and a light-shielding sheet 5. The upper surface of the circuit board 1 has a first solder pad 11 for electrical connection. The light-emitting unit 2 is soldered and fixed to the first solder pad 11 of the circuit board 1 via substrate pins 24 at its bottom. The encapsulation layer 3 is composed of cured colloid and covers at least the top, sides, and bottom solder joint connection areas of the light-emitting unit 2, as well as a predetermined width of the circuit board 1 surrounding the light-emitting unit 2, serving a fixing and protection function. The light guide sheet 4 is laid on the encapsulation layer 3 and has a lamp groove 41 corresponding to the position of the light-emitting unit 2. The light-emitting unit 2 and part of the encapsulation layer 3 above it are precisely accommodated within the lamp groove 41. The light-shielding sheet 5 is laid on top of the light guide sheet 4 and is connected to the four periphery of the circuit board 1 (e.g., by double-sided adhesive) through its edge to prevent light leakage.

[0033] The light-emitting unit 2 is a pre-packaged independent device. It includes a substrate 22, on the front side of which a second substrate pad 25 is provided. A flip-chip light-emitting chip 21 with its electrodes 27 facing down is directly bonded to the second substrate pad 25 via a reflow soldering process. The light-emitting chip 21 and its bonding area are completely encapsulated and protected by an encapsulation layer 28 (e.g., epoxy resin or silicone). The back side of the substrate 22 is provided with substrate pins 24 for connection to external circuitry (i.e., the first pad 11 of the circuit board 1).

[0034] The core is to first mass-produce ultra-thin, highly reliable independent light-emitting units 2 on the array substrate through mass transfer, reflow soldering and overall molding processes, and then optically sort them; then the sorted light-emitting units 2 are mounted and soldered onto the keyboard circuit board 1 like ordinary components, and then local secondary encapsulation is performed (forming encapsulation layer 3); finally, light guide sheet 4 and light shield 5 are assembled to complete the manufacturing of the entire backlight module.

[0035] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip, characterized in that, Includes the following steps: S1. Pre-package the light-emitting chip (21) to form a light-emitting unit (2); S2. Mount the light-emitting unit (2) onto the circuit board (1); S3. The pins (24) of the light-emitting unit (2) are soldered and fixed to the first pad (11) on the circuit board (1) by reflow soldering. S4. Perform secondary encapsulation coating on the top, side, and bottom solder joint connection areas of the light-emitting unit (2) and the surrounding circuit board (1) area after welding. S5. Curing the adhesive layer coated by the secondary encapsulation to form the encapsulation layer (3); S6. The light guide sheet (4) with the lamp groove (41) is laid on the circuit board (1) so that the light-emitting unit (2) and the encapsulation layer (3) are accommodated in the lamp groove (41); S7. The light-shielding sheet (5) is laid on the light guide sheet (4), and the edge of the light-shielding sheet (5) is connected to the edge of the circuit board (1); S8. Inspect the assembled backlight module.

2. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 1, characterized in that, Step S1 includes: S11. Prepare a substrate (22), form a fine conductive line and a second pad (25) for carrying the light-emitting chip (21) on the front side of the substrate (22), form a pin (24) for external connection on the back side of the substrate (22), and provide a metallized through hole (29) in the substrate (22) to realize the electrical connection between the second pad (25) and the pin (24); S12. Using mass transfer technology, the flip-chip (21) is transferred and bonded to the second pad (25) on the front side of the substrate (22) to form a light-emitting chip array; S13. The light-emitting chip array is integrally molded and packaged to form an encapsulation colloid layer (28) covering all light-emitting chips (21), thereby obtaining a light-emitting unit array; S14. Perform optical detection on the light-emitting unit array and generate a graded level mapping spectrum based on the detection results; S15. According to the graded level mapping spectrum, the light-emitting unit array is precisely cut to separate it into independent individual light-emitting units (2); S16. Based on the graded level mapping spectrum, the independent light-emitting units (2) are sorted and classified.

3. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, characterized in that, In step S11, the substrate (22) is selected from a rigid substrate composed of a glass substrate, a ceramic substrate, or a resin-based composite material substrate, or a flexible circuit board composed of polyimide-based or liquid crystal polymer-based materials; the line width and line spacing of the micro-conductive lines are both between 10 μm and 100 μm; the diameter of the metallized via is between 5 μm and 100 μm.

4. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 3, characterized in that, When the substrate (22) is a glass substrate, the diameter of the metallized via is 5μm to 50μm, and a hole-in-the-pan structure is formed by laser drilling and electroplating filling processes.

5. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, characterized in that, In step S12, the electrode (27) of the light-emitting chip (21) is connected to the second pad (25) of the substrate through a reflow soldering process with a peak temperature of 200°C to 300°C.

6. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, characterized in that, In step S13, epoxy resin or silicone is used for molding and encapsulation to form the encapsulation adhesive layer (28).

7. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, characterized in that, In step S15, the cutting path avoids the effective area of ​​the light-emitting chip (21) by at least 20 μm; and based on the graded level mapping map, the area determined to be unqualified can be skipped for cutting.

8. The method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, characterized in that, The execution order of steps S14, S15, and S16 can be adjusted as follows: first, step S15 is executed to cut and separate the components, then step S14 is executed to perform optical detection and grading on the individual light-emitting units (2), and finally step S16 is executed to sort the components based on the grading results.

9. In the method for manufacturing a keyboard backlight module based on a pre-packaged light-emitting chip according to claim 2, in step S2, before mounting the light-emitting unit (2) onto the first pad (11) of the circuit board, die bonding solder is coated on the first pad (11) of the circuit board.

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