A Side Package Structure, Packaging Process and Packaging Device for an Integrated Circuit Board

Abstract

The present invention discloses a side encapsulation structure for an integrated circuit board, which is used to realize the encapsulation of the side of the integrated circuit board, including a side encapsulation structure and a junction edge encapsulation structure; the side encapsulation structure and the junction edge encapsulation structure are formed by 3D printing in a linear manner, and the junction edge encapsulation structure covers the adjacent front and back regions on the side of the integrated circuit board and the edge region of the side encapsulation structure. The present invention also discloses a side encapsulation process and an encapsulation device for an integrated circuit board. By means of the direct writing 3D printing technology, the present invention can print the encapsulation structure on the side of the integrated circuit board, effectively cope with complex topographies, realize linear encapsulation of non-planar surfaces, improve the uniformity and density of encapsulation, prevent water vapor from entering and oxidation, inhibit the migration of metal ions in the side conductors, prevent open circuits after being knocked, significantly reduce the complexity of the side encapsulation process, improve the production efficiency, and can realize an encapsulation structure with high flatness and low aspect ratio, which conforms to the development trend of device thinning.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and particularly to a side packaging structure, a packaging process and a packaging device for an integrated circuit board. Background Art

[0002] As electronic devices become smaller, lighter and more advanced, the integrated circuit boards used in them have higher and higher integration levels. Some special integrated circuit boards also have multiple groups of circuits on the side, such as a miniLED display board. Because there are many LED modules, there are dense metal wire circuits on its side, and the wire pitch is between 100-300 μm, and it is more common to be composed of silver wires. Under the action of a DC voltage gradient and in a humid environment, adjacent wires are prone to silver ion migration, resulting in device short-circuit failure. Not only silver, but currently metals such as copper and titanium are also becoming more and more common as wires for electronic components. However, copper wires are prone to oxidation in a water vapor environment, resulting in a decrease in conductivity, and titanium wires are prone to deformation and open circuit due to softness and easy collision, which determines that their applications require a packaging protective layer.

[0003] Currently, commonly used packaging means such as scraping and pad printing cover the lines with a dense material to prevent water vapor from entering and prevent the lines from being knocked. However, due to the dense metal wire wiring of miniLED device products, some positions are short in length, and there are solder bumps on the surface of the substrate. The water isolation layer formed by the traditional process may have problems such as uneven thickness and inaccurate position. In addition, the scraping process is generally easy to scrape the bottom metal wire, resulting in short-circuit situations. At the same time, when packaging non-planar surfaces, it will bring problems such as poor flatness and insufficient density of the packaging structure in the processing area, and the complete packaging of metal wires cannot be achieved. Due to the fact that the rubber head of the pad printing technology works by elasticity and has limited elasticity, it is impossible to pad print a large-area isolation layer film. The rubber head needs to be replaced regularly, increasing the cost. Moreover, due to the different packaging shapes and morphologies of each part of products such as miniLED, for the packaging of special shaped surfaces, pad printing cannot be carried out due to the working principle of its rubber head.

[0004] In addition, for silver ion migration, the current technology mainly expands the silver wire spacing and makes an isolation structure. For the isolation structure, an insulating layer with a certain width can be applied between adjacent silver wires, which has problems such as the need to apply numerous insulating structures, cumbersome processes and high costs. Summary of the Invention

[0005] Aiming at the above problems existing in the prior art, the present invention proposes a side packaging structure, a packaging process and a packaging device for an integrated circuit board.

[0006] The present invention discloses a side packaging structure for an integrated circuit board, which is used to achieve the packaging of the side of the integrated circuit board. Metal wires are provided on the side of the integrated circuit board, including a side packaging structure and a junction edge packaging structure. The side packaging structure and the junction edge packaging structure are formed by 3D printing linearly. The side packaging structure covers the side of the integrated circuit board, and the junction edge packaging structure covers the adjacent front and back regions of the side of the integrated circuit board and the edge region of the side packaging structure.

[0007] Preferably, the side packaging structure and the junction edge packaging structure include at least one packaging component obtained by 3D printing processing.

[0008] The packaging component is a structure obtained by 3D printing. Preferably, it is one, that is, the side can be covered by one-time 3D printing, which can significantly improve the processing efficiency. Multiple packaging components can also be set, that is, multiple 3D printings or single-round-trip printings are required.

[0009] Preferably, chamfers are provided at the junctions of the side of the integrated circuit board with the front and back. The junction edge packaging structure covers the side packaging structure with a width of 5%-10% of the chamfer radius.

[0010] Preferably, the height of the side packaging structure is 10-100 μm, the height difference is ±20%, the width is 95%-100% of the width of the side of the integrated circuit board, and the aspect ratio of the side packaging structure <0.3.

[0011] Preferably, the height of the junction edge packaging structure is 10-20 μm, and the width is 50-200 μm.

[0012] Preferably, the resistivity change amplitude of the metal wires on the side of the integrated circuit board covered by the packaging structure is ≤10% after being tested for 500 hours under the conditions of 85°C and 85% humidity.

[0013] The present invention also discloses a side packaging process for an integrated circuit board, which is used to achieve the packaging of the side of the integrated circuit board, and includes the following steps: S1. Side packaging, using a packaging material to perform 3D printing processing on the side of the integrated circuit board to obtain a side packaging structure; S2. Adjacent front and back packaging, using a packaging material to perform 3D printing processing on the adjacent front and back of the side of the integrated circuit board to obtain a junction edge packaging structure.

[0014] Preferably, a curing step is further included, which is used to cure the side packaging structure and the junction edge packaging structure printed on the integrated circuit board. The curing step includes curing the side, the adjacent front and back after step S2 and / or the curing step is set to be synchronized with the 3D printing during steps S1 and S2 or performed separately after 3D printing.

[0015] The curing step may be performed after steps S1 and S2, that is, the side packaging structure and the boundary edge packaging structure are uniformly cured after the 3D printing process is completed.

[0016] The curing step can also be performed after the side packaging structure is completed in step 1, and the border edge packaging structure is cured after the boundary edge packaging structure is completed in step 2.

[0017] The curing step can also be performed simultaneously with the 3D printing process, that is, the printed packaging component is cured during the 3D printing process.

[0018] The curing step can be completed at one time or in steps. The distributed completion includes pre-curing the side packaging structure and the interface edge packaging structure simultaneously with or after the 3D printing process in steps S1 and S2, and then performing another curing after steps S1 and S2 to complete the curing treatment of the packaging structure.

[0019] Preferably, the dynamic viscosity of the packaging material is 3000-12000 cps.

[0020] Preferably, the packaging material is UV glue.

[0021] Preferably, the packaging material includes a first packaging material for side packaging and a second packaging material for adjacent front and back packaging; the first packaging material has a dynamic viscosity of 3000-6000cps; the second packaging material has a dynamic viscosity of 8000-12000cps.

[0022] The first packaging material and the second packaging material are UV glue. Compared with the more common three-proof glue, most of them adopt glue of thermal curing or moisture curing system. The inventor found in the actual use that the thermal curing glue has a micron-level precision. Because the viscosity of the glue gradually decreases with the increase of temperature, the leveling property is significantly enhanced, and the uniformity and flatness of the processed film thickness cannot be guaranteed; and the moisture-cured glue will also slowly solidify due to the water vapor in the atmospheric environment, which brings the risk of clogging the needle and is not suitable for the 3D printing process. This patent uses UV curing glue as the packaging material. On the one hand, UV glue needs to be excited by a light source of a specific wavelength to solidify. It is very stable at room temperature or in a light-proof environment, and is suitable for the long-term processing of 3D printing; at the same time, when this type of material is cured under the excitation of a light source of a specific wavelength, the material has good shape retention and low shrinkage, which can ensure the uniformity and flatness of the film thickness after solidification.

[0023] Preferably, a chamfer is provided at the junction between the side surface of the integrated circuit board and the front surface and the back surface. The inner diameter (W2) of the 3D printing needle outlet used in the 3D printing process in step S1 is selected according to the following formula:

[0024] W2 = W0 + α(sqrt3)r, 1 ≤ α < 3;

[0025] Where r is the radius of the arc chamfer at the side edge of the integrated circuit board, W0 is the width of the side plane of the integrated circuit board, and α is a process coefficient; the width of the side packaging structure is 95%-100% of the width of the side of the integrated circuit board, and the width of the side of the integrated circuit board is the thickness of the integrated circuit board.

[0026] Preferably, chamfers are provided at the junctions of the side of the integrated circuit board with the front and back. The height of the packaging structure at the junction edge is 10-20 um, and the width is 50-200 um; when performing 3D printing on adjacent front and back sides in step S2, the distance m between the center line of the printing needle and the chamfer edge of the integrated circuit board is set according to the following formula:

[0027] m = R - βr (0.05 < β < 0.1);

[0028] Where R is the inner diameter of the discharge port of the printing needle, r is the chamfer radius, and β is a process coefficient.

[0029] Preferably, in the 3D printing in steps S1 and S2, a pre-travel is provided before reaching the discharge position. Within the pre-travel range, the needle reaches the preset printing speed, and the pre-travel distance ≥ 1 mm.

[0030] The present invention also discloses a side packaging device for an integrated circuit board, including: a machine table and a motion system. The machine table is used to support the components of the device, and the motion system is used to drive the printing system or the material clamping system to perform three-axis motion, including an X-axis module, a Y-axis module, and a Z-axis module; a printing system, including a pressure feeding component and at least one printing head component; a material clamping system, including a turntable system and an adsorption system. The adsorption system includes a vacuum chuck and a negative pressure component; the turntable system includes a swing part and a rotation part. The swing part rotates around a swing rotation axis, and the rotation part is arranged on the swing part and rotates around a rotation axis. The rotation axis and the swing axis are perpendicular to each other, and the vacuum chuck is arranged on the rotation part; the driving power source for the rotation of the swing part and the rotation part is a motor; a curing system, used to cure the packaging structure printed and formed by the printing system.

[0031] Preferably, the printing head component includes a printing needle, a printing needle seat, a connector, a material tube, and a connection fixture. The printing needle is connected to the pressure feeding component through the printing needle seat, the connector, and the material tube in sequence, and the connector or the printing needle seat is fixed to the Z-axis module of the motion system through the connection fixture.

[0032] Preferably, the encapsulation device further includes an observation system, a measurement system, and an alignment system; the observation system includes a first lens barrel, a first light source, a first objective lens, a first industrial camera, and a first mounting fixture; the first industrial camera is mounted on the Z-axis module of the motion system at a preset angle inclined to the Z-axis direction; the measurement system includes a second lens barrel, a second light source, a second objective lens, a second industrial camera, a laser distance sensor, and a second mounting fixture; the second industrial camera is mounted on the Z-axis module of the motion system perpendicular to the XY plane; the alignment system includes a needle alignment sensor, a needle alignment silicon wafer, and a mounting fixture; the needle alignment sensor is a pressure sensor for calibrating the relative position relationship between the printing needle and the laser sensor in the Z-axis direction; the needle alignment silicon wafer is used to calibrate the relative position relationship between the printing needle, the laser sensor, and the second industrial camera in the XY plane.

[0033] The encapsulation structure involved in the present invention can be prepared by the encapsulation process involved in the present invention. The encapsulation structure and encapsulation process involved in the present invention can be realized relying on the encapsulation device involved in the present invention, or can be realized relying on other 3D printing devices in the prior art.

[0034] Through the direct writing 3D printing technology, the present invention prints the encapsulation structure on the side area of the integrated circuit board, which can effectively cope with complex topographies, realize linear encapsulation of non-planar surfaces, improve the uniformity and density of encapsulation, prevent water vapor from entering, and can be widely applied to the encapsulation of side conductors, such as silver, copper, titanium, aluminum, etc. Within 500 hours of testing under the conditions of 85°C and 85% humidity, the resistivity change range of the side of the integrated circuit board covered by the encapsulation structure is ≤10%, which can effectively inhibit the migration of metal ions in the wire, and at the same time effectively protect the metal wire, reducing or avoiding problems such as oxidation and bumping.

[0035] The direct writing 3D printing encapsulation device and process can meet the encapsulation of specific patterns on different-shaped surfaces by programming the path and replacing the print head, with the advantages of high repeatability and freedom, significantly reducing the complexity of the side encapsulation process, realizing multi-sided coverage (i.e., chamfer coverage) and special-shaped encapsulation processes, improving production efficiency, and at the same time being compatible with different types of materials, pollution-free throughout the encapsulation process, and having high material utilization rate.

[0036] In addition, through the integration of the software and hardware of the device and the matching of appropriate materials and processes, a linear encapsulation structure with high flatness with a film thickness height difference within 20% can be realized. The thickness of the linear encapsulation structure can be precisely controlled within 10-100 μm, and a linear encapsulation structure with a low aspect ratio (line height: line width less than 0.3, preferably less than 0.1) can be manufactured at one time. The encapsulation structure with a low aspect ratio can reduce the amount of encapsulation material used while ensuring good insulation, reduce the volume increase after encapsulation, and conform to the development trend of device thinning. Brief Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is the overall schematic diagram of the packaging device provided by the present invention;

[0039] Figure 2 is the front schematic diagram of the packaging device provided by the present invention;

[0040] Figure 3 is the structural schematic diagram of the material clamping system of the packaging device provided by the present invention;

[0041] Figure 4 is the structural schematic diagram of the printing system of the packaging device provided by the present invention;

[0042] Figure 5 is the structural schematic diagram of the observation system and measurement system of the packaging device provided by the present invention;

[0043] Figure 6 is the structural schematic diagram of the cleaning and alignment system of the packaging device provided by the present invention;

[0044] Figure 7 is the partial enlarged schematic diagram of the packaging device provided by the present invention;

[0045] Figure 8 is the side packaging schematic diagram of the side packaging process provided by the present invention;

[0046] Figure 9 is the adjacent front and back packaging schematic diagram of the side packaging process provided by the present invention;

[0047] Figure 10 is the partial schematic diagram of the integrated circuit board after being packaged by the side packaging process of the present invention;

[0048] Figure 11 is the partial enlarged schematic diagram of the chamfer of the integrated circuit board after being packaged by the side packaging process of the present invention;

[0049] Figure 12 is the partial enlarged schematic diagram of the silver wire arrangement during the packaging test of the packaging structure of the present invention;

[0050] Figure 13 is the morphology schematic diagram of the product after the 85°C / 85RH aging test during the packaging test of the packaging structure of the present invention;

[0051] Figure 14 It is a schematic diagram of the morphology after 3 days of 85°C / 85RH aging test on a partial encapsulation test product of the encapsulation structure of the present invention. Detailed implementation manners

[0052] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0053] As shown in the appended Figure 1-6 drawings, the present invention relates to a side encapsulation device for an integrated circuit board, which includes a machine table and a motion system 1, a printing system 2, a material clamping system 3, and a curing system 4.

[0054] As shown in the appended Figure 1 、 2 drawings, the machine table and the motion system 1 include a machine table 11 and a motion system 12. The machine table 11 is used to support the components of the device. In one embodiment of the present invention, the machine table 11 includes a gantry 111, a marble column 112, and a marble platform 113, and it can also be of other structures or materials.

[0055] The motion system 12 is used to drive the printing system or the material clamping system to perform three-axis motion; as shown in the appended Figure 1 drawings, it includes an X-axis module 121, a Y-axis module 122, and a Z-axis module 123, all of which are high-precision motion control systems. In one embodiment of the present invention, the positioning accuracy of the motion system 12 is ±2.5 μm, and the repeat positioning accuracy is ±0.5 μm. It is the basis for realizing high-precision processing capabilities, and the motion trajectory can be freely controlled by programming, and different encapsulation patterns can be printed on the plane as required.

[0056] As shown in the appended Figure 4 drawings, the printing system 2 includes a pressure feeding component (not shown in the figure) and a print head component 22. The pressure feeding component extrudes the slurry to the print head component 22 according to the set extrusion pressure, and the pressure feeding component can push the slurry by means of air pressure, hydraulic pressure, electric pressure, mechanical pressure, etc.

[0057] The print head component 22 is composed of a print needle 220, a print needle seat 221, a adapter 222, a material tube 223, and a adapter fixture 224.

[0058] The print needle 220 is sequentially connected to the pressure feeding component through the print needle seat 221, the adapter 222, and the material tube 223.

[0059] The adapter 222 or the print head needle base 221 is fixed to the motion system 12 through an adapter fixture 224, specifically fixed to the Z-axis module 123 of the motion system 12.

[0060] The print head 220 is commonly made of ceramic material or stainless steel material, and its inner and outer diameters are adjusted according to the requirements of the side encapsulation process. The commonly used inner diameter of the needle is 50μm - 800μm. The print head needle base 221 is a standard part that fits print heads 220 of various inner diameters. The adapter 222 is a standard Luer lock head that fits the print head needle base 221 and the material tube 223. The replacement of the print head 220 can be conveniently realized.

[0061] In addition, multiple print head assemblies 22 can be provided to reduce the replacement process of the print head 220.

[0062] As shown in the appendix Figure 3 As shown, the material clamping system 3 includes a turntable system 31 and an adsorption system. The adsorption system includes a vacuum chuck 321 and a negative pressure component (not shown in the figure); the material to be processed is adsorbed onto the vacuum chuck 321.

[0063] The turntable system includes a swing part 311 and a rotating part 312. The swing part 311 can rotate around its swing rotation axis, and the swing rotation axis is parallel to the X-axis direction shown in the appendix Figure 1 As shown. The rotating part 312 is arranged on the swing part 311 and rotates around its rotation axis, and the rotation axis is perpendicular to the plane of the swing part 311. The vacuum chuck 321 is arranged on the rotating part 312. The power sources of the swing part 311 and the rotating part 312 are motors. As shown in the attached drawing, the swing part 311 includes a bottom plate, side plates, and a rotating plate. The bottom plate is fixed to the Y-axis module 122, the side plates are vertically fixed to both sides of the bottom plate, and both ends of the rotating plate are rotatably connected to the two side plates and rotate driven by the motor. The rotating part 312 is arranged on the rotating plate.

[0064] The curing system 4 is used to cure the encapsulated structure printed by the printing system. It is arranged on the Z-axis module 123 of the motion system 12 and is located on one side of the print head assembly 22, so that the curing operation can be conveniently carried out.

[0065] The integrated circuit board side encapsulation device of the present invention further includes an observation system 5, a measurement system 6, and a cleaning and alignment system 7.

[0066] The observation system 5 includes a first high-precision variable magnification lens barrel 51, a first light source 52, a first objective lens 53, a first industrial camera 54, and a first mounting fixture 55.

[0067] As shown in the appendix Figure 5As shown, the viewing window of the first industrial camera 54 is connected to one end of the first high-precision zoom lens barrel 50. The other end of the first high-precision zoom lens barrel 50 is provided with a first objective lens 53. The first high-precision zoom lens barrel 50 is fixed to the motion system 12 through a first mounting fixture 55, specifically fixed to the Z-axis module 123 of the motion system 12. The first light source 52 is an annular light source, arranged outside the first high-precision zoom lens barrel 51 or the first objective lens 53, and is used to illuminate the observation area.

[0068] The first industrial camera 54 is mounted on the Z-axis at a certain angle, that is, there is an angle between the optical axis (also known as the camera central axis) of the first industrial camera 54 and the Z-axis. The mounting angle in this embodiment is 45°, which provides a clear field of view for observing the needle printing situation and simultaneously undertakes the function of visual alignment of the needle and the edge of the processing substrate in the X direction.

[0069] The measurement system 6 includes a second high-precision zoom lens barrel 61, a second light source 62, a second objective lens 63, a second industrial camera 64, a laser distance sensor 65, and a second mounting fixture 66.

[0070] As shown in the appendix Figure 5 As shown, the viewing window of the second industrial camera 64 is connected to one end of the second high-precision zoom lens barrel 61. The other end of the second high-precision zoom lens barrel 61 is provided with a second objective lens 63. The second high-precision zoom lens barrel 61 is fixed to the motion system 12 through a second mounting fixture 66, specifically fixed to the Z-axis module 123 of the motion system 12. The second light source 62 is a point light source, arranged outside the first high-precision zoom lens barrel 51 or the first objective lens 53 or the second mounting fixture 66, and is used to illuminate the observation area. In this embodiment, the second light source 62 is arranged outside the second mounting fixture 66.

[0071] The laser distance sensor 65 is arranged at the bottom of the second mounting fixture 66 and is parallel to the optical axis of the second industrial camera 64, with the working surface facing down.

[0072] The second industrial camera 64 is mounted on the Z-axis perpendicular to the XY plane, that is, the optical axis (also known as the camera central axis) of the second industrial camera 64 is parallel to the Z-axis.

[0073] The second industrial camera 64 is used to identify the Mark logo on the processing substrate plane and provide a reference coordinate for positioning during precision machining. The laser distance sensor 65 is used to scan the substrate topography and assist the device in compensating the height in real time during precision machining (so that the height of the printing needle and the processing surface is always the same). Even if the substrate flatness is poor, the device can still accurately control the printing film thickness. At the same time, in the automatic needle alignment process, the relative positions of each functional unit in the mechanical coordinate system can be obtained, and the coordinates of each functional unit during the processing process can be accurately tracked.

[0074] As shown in the appendixFigure 1 , 2 As shown in FIG. 7, in this embodiment, two Z-axis modules 123 are provided, and two printing systems 2 are installed. At the installation positions of each component, the printing system 2 is installed on the Z-axis module. Outside the printing system 2, the observation system 5 and the measurement system 6 are installed on the Z-axis module. In this embodiment, one of the Z-axis modules 123 is installed with one printing system 2, one observation system 5, and one measurement system 6, and the other Z-axis module 123 is installed with one printing system 2 and one curing system 4. The two printing systems 2 can be provided with printing needles of two different calibers according to requirements, and the two printing systems share one measurement system 6 and one curing system 4.

[0075] An integrated circuit board side packaging device involved in the present invention can perform various types of packaging according to needs, including the side packaging involved in the present invention, and can also perform full-front packaging. Through the setting of the two printing systems 2, it can be conveniently switched according to the process needs to improve work efficiency.

[0076] As shown in the attached Figure 6 , the cleaning and alignment system 7 includes a rubber wiping mechanism 71, a needle alignment sensor 72, a needle alignment silicon wafer 73, and a mounting fixture 74. The rubber wiping mechanism 71 is used to clean the printing needle; the needle alignment sensor 72 is a high-precision pressure sensor used to calibrate the relative position relationship between the printing needle 220 and the laser sensor in the Z-axis direction; the needle alignment silicon wafer 73 is used to calibrate the relative position relationship between the printing needle 220, the laser sensor, and the second industrial camera 64 in the XY plane.

[0077] Before the integrated circuit board packaging device operates, a calibration process needs to be carried out to determine the relative position relationship of the centers of the printing needle 220, the laser distance sensor 65, and the second industrial camera 64 in the XY plane. The calibration is only carried out once after each needle change.

[0078] The calibration process between the printing needle 220 and the center of the second industrial camera 64 is as follows:

[0079] 1. The printing needle 220 moves to the needle alignment silicon wafer 73 and prints 1 dot as a circular Mark, and records the coordinates at this time, denoted as X1, Y1;

[0080] 2. When the second industrial camera 64 is moved to a position where the circular Mark can be clearly seen within the field of view, visual calibration is used to identify the mechanical coordinates X2, Y2 when the center of the circular Mark is located at the center of the field of view of the second industrial camera 64;

[0081] 3. The relative position relationship (X1 - X2, Y1 - Y2) between the needle and the center of the second industrial camera 64 is obtained by calculating (X1, Y1) and (X2, Y2).

[0082] The calibration process of the relative position relationship between the printing needle 220 and the laser sensor in the Z-axis direction is as follows:

[0083] 1. Move the laser distance sensor 65 to the center of the sensing head of the needle sensor 72. Move the Z-axis to make the reading of the laser sensor 0 / close to 0, and record the Z coordinate Z1 at this time;

[0084] 2. The printing needle 220 moves to the needle sensor 72 according to the calibrated XY relative relationship, and is controlled by the program to move downward at a set speed, and record the coordinate Z2 after the pressure sensor outputs an induction signal;

[0085] 3. Calculate the relative position relationship between the needle of the printing needle 220 and the laser sensor in the Z-axis direction (Z1 - Z2);

[0086] The present invention relates to a side packaging process for an integrated circuit board, which will be described below in conjunction with specific processing examples.

[0087] Situation of the material to be processed: The packaging device and process involved in the present invention are particularly suitable for the side packaging of a miniLED glass substrate (hereinafter referred to as the substrate). The miniLED glass substrate is generally less than 1 mm, with an arc chamfer at the side edge and multiple silver lines on the side. The silver line spacing is generally 100 - 300 μm. The specific packaging process is as follows:

[0088] In this embodiment, the side is packaged first, and then the front and back are printed and packaged. The preferred dynamic viscosity of the UV glue in this embodiment is 8000 - 12000 cps, the suitable coating thickness range is 10 - 100 μm, and the curing UV irradiation dose is 350 - 500 MJ cm -2 (365 nm), and it can be cured after 5S of UV irradiation. Since the morphologies of the side, front, and back are different, although the main body is the same packaging glue, for side packaging, due to the relatively large packaging width, the chamfer coverage requires a certain fluidity to maintain flatness and chamfer coverage. Therefore, for side packaging, the material used is a UV glue with a dynamic viscosity of 3000 - 6000 cps.

[0089] 1. Side packaging is carried out by 3D printing: The material is UV glue with a dynamic viscosity of 3000 - 6000 cps. As shown in the attachment Figure 8 The inner diameter of the printing needle of the packaging device is W2, the substrate thickness is W1, there is an arc chamfer with a radius of r at the side edge, and the side plane width is W0. The inner diameter of the printing needle is selected according to the following formula, where α is related to the raw material characteristics. Generally speaking, the better the raw material leveling effect, the smaller α.

[0090] W2 = W0 + α(sqrt3)r, 1 ≤ α < 3.

[0091] 2. Fix the miniLED glass vertical substrate in the loading area, start the automation software, turn on the vacuum pump, the suction cup automatically adsorbs the substrate, and achieve automatic mechanical zeroing alignment and leveling adjustment.

[0092] 3. Determine the coordinates of the needle, camera, and high-precision height measuring instrument through the vision positioning software, upload the relative position relationship among the three to the software parameters, the pre-travel is greater than 1 mm, preferably 2 mm.

[0093] 4. Move the needle near the side edge of the substrate through vision. Before performing the scan, the high-precision height measuring instrument will move to this position through the relative position relationship, start the automatic edge finding program, obtain the edge coordinates of the scan area in the X and Y directions to accurately locate the scan area, and use the corrected corner points of the area as the scan starting point for rapid scanning, and record the flatness data of the substrate side area.

[0094] 5. Zero the distance of the pressing needle sensor with the help of the pressing needle sensor and the height measuring sensor to determine the Z-direction reference coordinate of the needle tip. The needle moves to 2 mm before the printing starting point according to the set needle surface distance parameter, the coordinate of the corrected scan area, and the corresponding height measurement value. The encapsulation device automatically opens the discharge through the automation software, and the needle starts to move at the set speed.

[0095] The software calls the height compensation data of the printing area and instantaneously adjusts the printing height during the printing process to ensure that the distance between the needle and the substrate remains consistent during the printing process. To obtain a better side encapsulation effect (side encapsulation width, chamfer coverage, side encapsulation thickness, etc.), various printing parameters need to cooperate to achieve. The main influencing parameters include printing air pressure, needle moving speed, needle surface distance, etc. In the embodiment of the present invention, the preferred printing air pressure is 5 psi, the needle moving speed is 35 mm / s, and the needle surface distance is 18 μm. At this time, the encapsulation width is appropriate, the chamfer coverage is good, and the thickness is 18 - 20 μm (before curing). When the needle surface distance is less than 15 μm, there will be an obvious situation of high on both sides and concave in the middle. When the needle surface distance is greater than 25 μm, the width of the UV glue is not enough to cover the chamfer, and even cannot cover the silver line, causing the silver line to be exposed.

[0096] For side printing, the needle follows the path programmed in the software. The UV encapsulation glue is evenly printed above the silver line on the side of the substrate along with the printing needle. And the UV glue has a certain fluidity and will flow downward along the chamfer to both sides, covering a part of the chamfer close to the side.

[0097] 6. After the edge encapsulation is completed, rotate the suction cup to the horizontal position and perform the front or back encapsulation: select the preferred UV glue and replace the printing needle. The front or back encapsulation mainly aims to completely cover the chamfer to achieve the preset encapsulation effect. Under the condition of meeting the insulation requirements, the smaller the width of the front and back encapsulations, the better, in order to reduce the impact on other processes. The height of the front and back encapsulations is 10 - 20um, and the width is 50 - 200um.

[0098] During the specific encapsulation process, as shown in the appendix Figure 8 When performing UV glue 3D printing on the front or back, the distance m between the center line of the printing needle and the chamfer edge is set according to the following formula:

[0099] m = R - βr (0.05 < β < 0.1);

[0100] where R is the inner diameter of the printing needle outlet, and r is the chamfer radius.

[0101] In the appendix Figure 9 , l1 is the center line of the printing needle, l2 is the perpendicular line of the front and back chamfer edges, and l3 is the side line of the printing needle close to the chamfer. The distance between l1 and l3 is R, that is, the inner diameter of the printing needle outlet. The distance between l1 and l2 is m, and the distance between l2 and l3 is n, that is, the distance of the printing needle outlet exposed from the chamfer part. The chamfer radius is r. Under the premise of ensuring relatively uniform coverage of the chamfer, according to experience, n and r approximately satisfy n = βr, (0.05 < β < 0.1).

[0102] In the embodiment of the present invention, the preferred air pressure parameter is 9psi, the needle moving speed is 30mm / s, and the needle - to - surface distance is 15μm. The obtained encapsulation thickness is 18 - 21μm (before curing), and the encapsulation width is about 110μm. When the needle - to - surface distance is less than 10μm, the width will be too wide and affect the subsequent processes of the product. When the needle - to - surface distance is greater than 20μm, the upper edge of the encapsulation starts to twist, and the thickness is too high and uneven, which is not conducive to the encapsulation of the product.

[0103] 7. Repeat the zeroing, height compensation, and positioning processes in steps (2) - (5) to perform encapsulation printing on the front and back edges respectively. The UV glue printed near the edge side will be joined to the chamfer to achieve the connection of the encapsulation glue at the chamfer. It should be particularly noted here that, first, there are Mark points for positioning on the substrate surface, and precise positioning can be achieved through vision software; second, due to the existence of the chamfer, the vertical distance from the needle to the substrate surface in the direction of the substrate edge is different. In this solution, the distance from the needle to the substrate surface is uniformly used as the reference for the needle - to - surface distance parameter for printing.

[0104] 8. Curing process: After the three-sided encapsulation is completed, irradiate the surface of the UV glue with a UV lamp to cure and shape the encapsulation glue. The UV lamp can move along with the needle head and cure while printing and encapsulating, which can further improve the processing efficiency.

[0105] The specific process of the height compensation environment is as follows: Fix the miniLED glass substrate with a vacuum adsorption device; Align the printing needle head, the center of the field of view of the second industrial camera, and the laser distance sensor with specific points in the alignment area respectively, and the picked coordinates are (Xn, Yn), (Xc, Yc), and (Xs, Ys) respectively to obtain the relative position relationship among the three. With the help of the camera and vision, pick up the coordinates (Xm, Ym) of the Mark point or the benchmark point selected independently. The relative displacements in the x and y directions from the first point of the scanning area to the Mark point or the benchmark point selected independently are a and b respectively. Then the software can automatically move the sensor to (Xm + Xs - Xc + a, Ym + Ys - Yc + b) for laser ranging. It should be particularly noted that if vision alignment is adopted, an edge-finding program is added to improve the accuracy. The sensor will be positioned at the edge of the substrate near the scanning area. By measuring the height value of the sensor and analyzing the X and Y coordinates of the edge, data correction can be carried out to eliminate the deviation brought by vision. After scanning the surface of the selected area, obtain the compensation data Δz = f(x, y) of the area height. After the compensation is enabled, during the encapsulation process, by reading the compensation data of each point on the surface, the Z axis will change instantaneously with the X and Y coordinates, that is, the Z coordinate of the platform Z(x, y) = Z0 + z + Δz, keeping the distance between the needle surface constant, so as to make the thickness uniform. By controlling the movement speed of the printing needle head and the air outlet pressure of the dispenser by computer, stable material discharge and uniform line type are achieved. After the parameters are set, in order to ensure stable material discharge at the first printed point, a pre-travel X0 or Y0 is added. Taking the start printing direction as the X direction as an example, when the program is executed, the needle head will move to (Xm + Xn - Xc + a - X0, Ym + Yn - Yc + b, Z0 + z + Δz) for printing. Within the range of the pre-travel X0, the needle head will move to a uniform speed. After finishing the pre-travel, it will enter the printing area on the substrate to complete the printing and encapsulation.

[0106] After the sample encapsulation is completed, after longitudinally cutting the side of the substrate, the surface along the movement direction of the needle head is placed vertically upward and observed under the SEM for the side encapsulation structure image. As Figure 9 shown, it can be seen from the image that: First, the side encapsulation structure presents an arch shape, which is related to the slurry flow caused by the chamfers on both sides of the side on the one hand and the surface tension of the material itself on the other hand. Second, it is observed that the thickness of the middle area is about 16 μm, and the difference from the needle surface distance of 18 μm comes from the leveling of the UV glue to both sides and the curing shrinkage. Third, the encapsulation structure at the chamfers on both sides is well connected and no exposed phenomenon appears. Particularly, there is no significant change in thickness along the printing direction in the field of view, indicating good film thickness uniformity.

[0107] After multiple experiments and tests, using the device and encapsulation process involved in the present invention, a direct-write 3D printing UV glue linear encapsulation with an overall film thickness of the encapsulation structure within 10±2μm - 100±20μm, that is, a film thickness height difference within 20%, can be achieved. The encapsulation of special-shaped parts (including but not limited to chamfers) can be realized, the linear encapsulation of non-planar surfaces can be realized, and the film thickness height difference is ensured to be within 10μm; the aspect ratio of the overall encapsulation structure <0.3, preferably less than 0.1, and the film thickness height difference is within 20%.

[0108] As shown in the Figure 11 attachment, when observed through a super-depth-of-field microscope (tilted at 45°) at the chamfer of the substrate, it is found that no connecting wires appear at the connection, indicating good compatibility between the two materials.

[0109] In this application, UV glue is selected as the encapsulation material. The main reasons are that UV glue has the following characteristics: it is stable at room temperature, which can ensure the long-term stable use of the product; it has good shape retention during curing, which can ensure the flatness of the encapsulation structure after curing; and it has a relatively fast curing speed, which is easy to control and reduces the workload. Commonly used moisture-curing adhesives are not suitable for long-term operations and have insufficient stability under harsh conditions. Thermal-curing adhesives generally show better fluidity during the heating and curing process, which is not conducive to controlling the flatness of the encapsulation structure.

[0110] In terms of the encapsulation process, this application has the following technical effects: precise height control, the height of the encapsulation structure can be precisely controlled within 10 - 100μm, and the flatness is high. Multi-sided coverage, that is, chamfer coverage. Compared with other technologies (such as scraping coating), it cannot be evenly coated, and the chamfer can be completely covered. Special-shaped encapsulation, for example, it is impossible to pad-print the encapsulation structure onto a special-shaped surface using the pad-printing process, but this process can achieve it.

[0111] For the precise control of the flatness and height of the encapsulation structure, especially the side encapsulation structure, multiple influencing factors need to be considered, including the motion control of the encapsulation device, the realization of height compensation during specific encapsulation, the flowability of the encapsulation material, the setting of the pre-travel, the selection of process parameters such as printing parameters, etc. Through a large number of experiments and mechanism studies on the above influencing factors, the selected range of relevant parameters determined in this application has good applicability and excellent technical effects. The resistivity change amplitude of the side metal wires of the integrated circuit board covered by the encapsulation structure is ≤10% when tested under the conditions of 85°C and 85% humidity for 500 hours.

[0112] This process and packaging structure can be used for the side packaging of various different types of integrated circuit boards, providing good protection for the side metal wires and ensuring that their electrical conductivity remains unchanged during long-term use. In specific applications, the protection focus of each metal wire is different. For example, silver is prone to silver migration short circuit in water vapor, copper is prone to oxidation in water vapor, which increases the resistance, and titanium wires are relatively soft and prone to breakage after being knocked. A good packaging structure can provide complete protection for metal wires.

[0113] The following packaging tests were carried out on the selected packaging material (UV glue with a dynamic viscosity of 3000 - 6000 cps) and process in the above embodiments: Set the pitch of the silver wires to be less than 20 μm, the wire width to be 220 μm, the length to be 0.8 mm, and the thickness to be 5 μm. Select an 800-μm packaging needle to cover the entire group of silver wires, set the needle-to-surface distance to be 10 μm according to the above steps, and print a layer of UV glue on the silver wires to cover according to the above printing steps; irradiate the UV glue with a UV lamp to cure it; place the sample in a high-temperature and high-humidity test chamber, set the test conditions to 85°C / 85% RH, connect a constant current power supply, the current is 25 mA, and measure the voltage change at both ends of the silver wires within 500 hours and calculate the resistance at both ends.

[0114] The experimental results are as follows:

[0115] 1. As shown in the appendix Figure 12 The pitch of the silver wires is less than 20 μm. The film thickness measured by a precision height sensor is 12 ± 2 μm.

[0116] 2. The measured voltage and resistance change data within 500 hours at 85°C / 85% RH are shown in Table 1

[0117] Table 1 Results of 85°C / 85% RH accelerated aging test

[0118] Time / h 24 48 96 144 192 288 360 432 500 Voltage / V 3.36 3.35 3.36 3.34 3.32 3.36 3.34 3.35 3.37 Resistance / Ω 146.0 145.6 146 145.2 144.3 145.8 144.8 145.7 146.5

[0119] From the data in the table, it can be seen that the resistance change at both ends of the silver wires within 500 hours is < 10%, and it can be considered that no post-Ag migration phenomenon has occurred.

[0120] 3. The morphology of the product after one week of aging monitoring at 85°C / 85% RH is as shown in the appendix Figure 13 No silver migration is seen. The 85°C / 85% RH aging test refers to the reliability test of the test sample under the condition that the temperature of the test chamber is set to 85°C and the humidity is 85%.

[0121] To further verify the effect of the encapsulation layer on suppressing silver migration, a part of a silver wire on the substrate was encapsulated, and the other part was not encapsulated. After 3 days of accelerated aging, as shown in the appendix Figure 14As shown, through the microscope, it can be seen that there is an obvious silver migration layer on both sides of the silver wire in the unencapsulated part (the upper part of the attached drawing), while the silver wire in the part covered by the encapsulation glue (the lower part of the attached drawing) is still neat on both sides, and there is basically no silver migration phenomenon. This result comparison highlights the effect of the encapsulation layer on suppressing silver migration.

[0122] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or equivalently replace some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An edge packaging structure for an integrated circuit board, used to achieve the packaging of the side of the integrated circuit board. There are metal wires arranged on the side of the integrated circuit board. It is characterized in that, It includes a side encapsulation structure and a junction edge encapsulation structure; the side encapsulation structure and the junction edge encapsulation structure are formed by 3D printing linearly; the side encapsulation structure covers the side of the integrated circuit board, and the junction edge encapsulation structure covers the adjacent front and back regions of the side of the integrated circuit board and the edge region of the side encapsulation structure; There is a chamfer at the junction of the side of the integrated circuit board with the front and back, and the junction edge encapsulation structure covers 5%-10% of the width of the side encapsulation structure with the radius of the chamfer; The resistivity change range of the metal wires on the side of the integrated circuit board covered by the encapsulation structure is ≤10% when tested for 500 hours under the conditions of 85°C and 85% humidity.

2. The edge packaging structure for an integrated circuit board according to claim 1, characterized in that, The side encapsulation structure and the junction edge encapsulation structure include at least one encapsulation component obtained by 3D printing processing.

3. The edge packaging structure for an integrated circuit board according to any one of claims 1-2, characterized in that, The height of the side encapsulation structure is 10-100μm, the height difference is ±20%, the width is 95%-100% of the width of the side of the integrated circuit board, and the aspect ratio of the side encapsulation structure <0.

3.

4. The edge packaging structure for an integrated circuit board according to any one of claims 1-2, characterized in that, The height of the junction edge encapsulation structure is 10-20um, and the width is 50-200um.

5. An edge packaging process for an integrated circuit board, used to achieve the packaging of the side of the integrated circuit board. It is characterized in that, It includes the following steps: S1. Side encapsulation, using an encapsulation material to perform 3D printing processing on the side of the integrated circuit board to obtain a side encapsulation structure; S2. Adjacent front and back encapsulation, using an encapsulation material to perform 3D printing processing on the adjacent front and back of the side of the integrated circuit board to obtain a junction edge encapsulation structure; There is a chamfer at the junction of the side of the integrated circuit board with the front and back, and the junction edge encapsulation structure covers 5%-10% of the width of the side encapsulation structure with the radius of the chamfer; The resistivity change range of the metal wires on the side of the integrated circuit board covered by the encapsulation structure is ≤10% when tested for 500 hours under the conditions of 85°C and 85% humidity.

6. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, It also includes a curing step for curing the side encapsulation structure and the junction edge encapsulation structure printed on the integrated circuit board; the curing step includes curing the side, adjacent front and back after step S2 and / or the curing step is set to be carried out synchronously with 3D printing during steps S1 and S2 or carried out separately after 3D printing.

7. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, The dynamic viscosity of the encapsulation material is 3000-12000 cps.

8. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, The encapsulation material is UV glue.

9. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, The encapsulation material includes a first encapsulation material for side encapsulation and a second encapsulation material for adjacent front and back encapsulation; the dynamic viscosity of the first encapsulation material is 3000-6000 cps; the dynamic viscosity of the second encapsulation material is 8000-12000 cps.

10. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, The inner diameter W2 of the discharge port of the 3D printing needle used in the 3D printing processing in step S1 is selected according to the following formula: W2 = W0 + α(sqrt3)r, 1≤α<3; where r is the radius of the arc chamfer at the edge of the side of the integrated circuit board, W0 is the width of the plane of the side of the integrated circuit board, and α is a process coefficient; The width of the side encapsulation structure is 95%-100% of the width of the side of the integrated circuit board.

11. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, The height of the junction edge encapsulation structure is 10 - 20 um, and the width is 50 - 200 um; when performing 3D printing processing on adjacent front and back surfaces in step S2, the distance m between the center line of the printing needle and the chamfered edge of the integrated circuit board is set according to the following formula: m = R - βr (0.05 < β < 0.1); where R is the inner diameter of the discharge port of the printing needle, r is the chamfer radius, and β is the process coefficient.

12. The edge packaging process for an integrated circuit board according to claim 5, characterized in that, In the 3D printing processing in steps S1 and S2, a pre-travel is set before reaching the discharge position. Within the pre-travel range, the needle reaches the preset printing speed, and the pre-travel distance ≥ 1 mm.

13. An integrated circuit board side packaging device, characterized in that Including: A machine table and a motion system, where the machine table is used to support each component of the device, and the motion system is used to drive the printing system or the material clamping system to perform three-axis motion, including an X-axis module, a Y-axis module, and a Z-axis module; a printing system, including a pressure feeding component and at least one printing head component; A material clamping system, including a turntable system and an adsorption system, the adsorption system includes a vacuum chuck and a negative pressure component; the turntable system includes a swing part and a rotating part, the swing part rotates around a swing rotation axis, the rotating part is arranged on the swing part and rotates around a rotation rotation axis, the rotation rotation axis and the swing rotation axis are perpendicular to each other, and the vacuum chuck is arranged on the rotating part; a curing system, used to cure the encapsulation structure printed and formed by the printing system; The encapsulation device further includes an observation system, a measurement system, and a alignment system; The observation system includes a first lens barrel, a first light source, a first objective lens, a first industrial camera, and a first mounting fixture; the first industrial camera is installed on the Z-axis module of the motion system at a preset angle inclined to the Z-axis direction; The measurement system includes a second lens barrel, a second light source, a second objective lens, a second industrial camera, a laser distance sensor, and a second mounting fixture; the second industrial camera is installed on the Z-axis module of the motion system perpendicular to the XY plane; The alignment system includes a needle alignment sensor, a needle alignment silicon wafer, and a mounting fixture; the needle alignment sensor is a pressure sensor, used to calibrate the relative position relationship between the printing needle and the laser sensor in the Z-axis direction; the needle alignment silicon wafer is used to calibrate the relative position relationship between the printing needle, the laser sensor, and the second industrial camera in the XY plane.

14. The integrated circuit board side packaging device according to claim 13, characterized in that The printing head component includes a printing needle, a printing needle seat, a connector, a material pipe, and a connection fixture. The printing needle is sequentially connected to the pressure feeding component through the printing needle seat, the connector, and the material pipe. The connector or the printing needle seat is fixed to the Z-axis module of the motion system through the connection fixture.

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