An inkjet needle alignment method and its dispensing alignment method

Abstract

This invention discloses an inkjet head alignment method and its dispensing alignment method, relating to the field of chip spraying and packaging technology. It includes the following steps: S1: inkjet head alignment, including S1A: controlling the inkjet head to move from a preset origin coordinate to a printing position and printing a preset pattern; S1B: a vision camera acquires the pattern data obtained in step S1A; S1C: after analyzing and processing the pattern data obtained in step S1B, the coordinates of specific marker points of the printed preset pattern are obtained, and the inkjet head zero point is set to coincide with the specific marker points; S1D: the algebraic sum of the inkjet head printing position coordinates and the specific marker points in step S1C is used to calculate the deviation value between the inkjet head zero point and the inkjet head preset origin coordinates; furthermore, by providing a dispensing alignment method, based on the inkjet head zero point obtained after the aforementioned alignment, dispensing operations on chips on wafers can be performed quickly and accurately.

Description

Technical Field

[0001] This invention belongs to the field of chip packaging technology, and in particular relates to a vision-based inkjet needle alignment method and its dispensing alignment method. Background Technology

[0002] With the rapid development of economy and technology and the increasing market demand for semiconductors, wafers are the basic material for manufacturing semiconductor chips. Wafer dispensing technology is a crucial technology in advanced electronics manufacturing, widely used in chip packaging and integrated circuit equipment. Its purpose is to reduce the probability of component failure caused by factors such as temperature changes, drops, and vibrations during product use, thereby extending product lifespan. Therefore, as a key and core technology in electronic packaging, the improvement of dispensing technology directly affects the quality of packaging technology. However, traditional manual glue gun dispensing methods suffer from low production efficiency and uneven glue flow, easily leading to excessive glue dispensing and substandard production quality. Subsequently, dispensing equipment has emerged to replace traditional manual glue guns. For conventional needle-shaped dispensing equipment, since the dispensing center is the center of the needle, alignment can be achieved by observing the needle center. Currently, in order to further improve dispensing efficiency, dispensing quality, and the flexibility of dispensing pattern settings, our company has adopted an inkjet head structure for dispensing onto wafers. However, since the main body of the inkjet head is similar to a cube structure, the dispensing hole is small and invisible, making it difficult to quickly calibrate the zero point after replacement or maintenance. This makes the installation and alignment of the inkjet head difficult. Furthermore, when disassembling and repairing the inkjet head or replacing it with other specifications due to product needs, the difficulty of aligning the inkjet head will be far greater than the difficulty of aligning the metering valve. Once there is an excessive misalignment, it can easily lead to deviations in the amount of adhesive or misalignment of patterns in batch products. Summary of the Invention

[0003] The purpose of this invention is to provide an inkjet needle alignment method and a dispensing alignment method to solve the alignment difficulty problem caused by the invisible dispensing hole of traditional inkjet heads.

[0004] To solve the above-mentioned technical problems, the objective of this invention is achieved as follows:

[0005] An inkjet needle alignment method includes the following steps:

[0006] S1: Inkjet head alignment, including

[0007] S1A: Controls the inkjet head to move from the preset origin coordinates to the printing position and prints the preset pattern;

[0008] S1B: Acquire the pattern data printed in step S1A using a vision camera.

[0009] S1C: Analyze and process the pattern data to obtain the coordinates of specific marker points of the preset pattern, and set the inkjet head zero point to coincide with the specific marker points;

[0010] S1D: Based on the algebraic operation between the printing position coordinates of the inkjet head and the coordinates of the specific identification point, calculate the deviation value between the inkjet head zero point and the preset origin coordinates.

[0011] As a further preferred embodiment of the above implementation: the zero-point coordinate of the inkjet head is obtained by compensating for the deviation value through a preset origin coordinate.

[0012] As a further preferred embodiment of the above implementation: the preset pattern is a rectangle, and the specific marking point is any corner of the rectangle.

[0013] In addition, a dispensing alignment method for inkjet needle alignment is disclosed, including the following steps.

[0014] S2: Obtaining the origin position of the adhesive spray, including:

[0015] S2A: Preset adhesive spraying pattern; This preset adhesive spraying pattern includes adhesive head alignment points, wafer mark alignment points, and chip alignment points;

[0016] S2B: Wafer Image Acquisition; The wafer is placed on a dispensing platform, and a vision camera is used to acquire the wafer image;

[0017] S2C: Obtain the coordinates of the wafer's mark; analyze and process the wafer image to determine the coordinate position of the wafer's mark;

[0018] S2D: Wafer alignment; control the dispensing platform to move the wafer so that the wafer mark coordinates coincide with the wafer mark alignment point coordinates in step S2A, thus completing the wafer alignment;

[0019] S3: Spraying glue alignment; control the movement of the inkjet head so that the inkjet head zero point determined in step S1 coincides with the spraying glue head alignment point;

[0020] S4: Spray adhesive; controls the inkjet head to perform adhesive spraying according to the preset adhesive spraying pattern.

[0021] As a further preferred embodiment of the above implementation: step S2C further includes: calculating the deflection angle and X / Y direction deviation value between the wafer and the preset adhesive pattern based on the wafer mark coordinates; in step S2D, the adhesive dispensing platform drives the wafer to perform rotation compensation and translation compensation.

[0022] As a further preferred embodiment of the above implementation: step S2A or step S4 includes the step of converting the preset adhesive pattern into pixel size.

[0023] As a further preferred embodiment of the above implementation: the preset adhesive spraying pattern includes a rectangular boundary, the rectangular boundary is located outside the adhesive spraying area of ​​the chip, and any corner of the rectangular boundary is the adhesive spraying head alignment point.

[0024] As a further preferred embodiment of the above implementation: the preset adhesive spraying pattern in step S2A includes adhesive spraying images of the same size and distribution as the chips on the wafer, wherein the area where the adhesive spraying image corresponding to the chip is located forms an inkjet area, and the remaining area within the rectangular boundary is a blank area.

[0025] The significant and beneficial technical advantages of this invention compared to existing technologies are: it solves the problem of easily and quickly locating the reference position of the inkjet head after replacement or displacement, thus determining a precise inkjet head zero point for the system and facilitating subsequent processes. Furthermore, this invention provides a dispensing alignment method based on the aforementioned inkjet head zero point, enabling rapid and precise dispensing of adhesive to chips on wafers. Using this method, inkjet head alignment time is reduced to 1 / 3 of traditional methods, and alignment accuracy is improved to ±5μm. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preset pattern and specific marker locations;

[0027] Figure 2 This is a schematic diagram showing the alignment relationship between the preset adhesive spray pattern and the wafer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the given embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] In the description of this application, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] In the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0031] In the description of this application, the inkjet head zero point refers to the reference positioning point of the inkjet head's ejection pattern, and the wafer mark refers to the physical identification point on the wafer surface used for positioning.

[0032] This invention discloses an inkjet needle alignment method and its dispensing alignment method, comprising the following steps:

[0033] S1: Inkjet head alignment, including

[0034] S1A: The preset origin coordinates of the inkjet head are (X0, Y0), controlling the inkjet head to move to the printing position to print the preset pattern; the coordinates of the printing zero point are (X0+Xf, Y0+Yf); where (X0, Y0) are the preset origin coordinates, and (Xf, Yf) are the inkjet head movement distances. That is, driven by the drive component, the inkjet head moves a distance Xf in the X direction and a distance Yf in the Y direction to reach the printing position; at this point, the inkjet head coordinates become (X0+Xf, Y0+Yf). The requirement for printing the preset pattern is that the inkjet head dispenses all the ink; therefore, the boundary of this preset pattern is the printing boundary of the inkjet head.

[0035] S1B: The vision camera acquires the pattern data obtained from printing in step S1A; the vision camera moves above the pattern printed in step S1A and takes a picture of the pattern, transmitting the captured image information to the host.

[0036] S1C: After analyzing and processing the pattern data obtained in step S1B, obtain the coordinates of specific marker points on the pattern; set the inkjet head zero point to coincide with the specific marker point. This specific marker point needs to have characteristics that facilitate camera capture and subsequent analysis and filtering; for example, in this embodiment, it is preferable to preset the pattern as a fully printed state with the inkjet head covering the entire surface. After full printing, a rectangular pattern is obtained, and any corner of this pattern is used as a specific marker point (e.g., ...). Figure 1 Point A in the upper left corner of the pattern is the easiest to identify and select because the corner is located at the boundary between the pattern and the area outside the pattern. Alternatively, during the later glue application, a rectangular area identical to the area covered by the inkjet head can be pre-defined within the system as the boundary of the glue application pattern. The same corner of this boundary can be used as the pre-defined positioning point for the glue application pattern. In other words, when the inkjet head and the glue application pattern are in the same coordinate system, simply aligning the specific marker point with the positioning point of the glue application pattern will allow the inkjet head to obtain a pattern identical to the pre-defined glue application pattern. In this embodiment, the upper left corner of the pre-defined pattern is selected as the specific marker point (it should be noted that this specific marker point...). Figure 1The position of marker point A corresponds to the zero point position of the upper left corner of the inkjet head. Since the pattern data analysis and processing is performed in the coordinate system of the vision camera / vision system, the specific marker point after final analysis and processing is transformed into the world coordinate system of the machine. The center coordinates (Xc, Yc) of the vision camera are the coordinates in the world coordinate system. Therefore, the coordinates of the specific marker point are (Xc+XS, Yc+Ys), where (Xs, Ys) are the coordinate values ​​of the specific marker point in the coordinate system of the vision camera / vision system, with the center of the vision camera as the origin.

[0037] S1D: Calculate the deviation (△Xco, △Yco) between the inkjet head zero point and the preset origin coordinates by using the difference between the inkjet head printing position coordinates (X0+Xf, Y0+Yf) and the coordinates (Xc+XS, Yc+Ys) of the specific marked point in step S1C. Then, by compensating this relative coordinate (△Xco, △Yco) with the preset origin coordinates of the inkjet head, the inkjet head zero point coordinates can be obtained. Subsequently, aligning these inkjet head zero point coordinates with the set printing zero point of the printing area will allow for accurate glue application.

[0038] S2: Obtaining the origin position of the adhesive spray, including:

[0039] S2A: Preset adhesive spraying pattern; This adhesive spraying pattern is designed according to the actual chip distribution and dimensions on the wafer to ensure that the final adhesive spraying meets the design requirements. Preferably, the preset adhesive spraying pattern has a rectangular boundary, which is located in the same world coordinate system as the dispensing platform. The coordinates of the upper left corner of the rectangular boundary (the adhesive head alignment point) are set to (Xy, Yy). Furthermore, the preset adhesive spraying pattern also includes preset alignment points (Xym, Yym) corresponding one-to-one with the wafer mark and alignment points (Xyd, Yyd) for the second specific identifier point of a DIE.

[0040] S2B: Wafer Alignment; The wafer is placed on a dispensing platform, and a vision camera takes a picture of the wafer on the platform to acquire an image. This step includes moving the vision camera to a preset position above the dispensing platform. That is, once this preset position is determined, the vision camera will move to this preset position every time the wafer is photographed. Alternatively, the vision camera can be fixed at this preset position to reduce the complexity of the control unit and lower equipment costs. The center of the vision camera at this preset position will then have coordinates (Xj, Yj).

[0041] S2C: Obtain the coordinates of the wafer's mark; analyze and process the wafer image obtained in step S2B to obtain the coordinates of the wafer's mark; specifically, place the wafer on the dispensing platform, and at this time, the vision camera moves to a preset position above the dispensing platform to take a picture of the wafer. Since there are mark marks on the wafer, the vision camera transmits the captured wafer image to the host computer, and the host computer analyzes and processes the wafer image to obtain the position of the wafer's mark point. Multiple chips, or DIEs (Device Ingredients, referring to fully functional chip units cut from the wafer... circuit board pads with metal wires connecting to external pins), are distributed on the wafer. The area where the DIE chips are located is the area requiring adhesive application. After the wafer is designed and manufactured, the relative positions of the wafer's mark points and the chips are determined and unique. Therefore, after obtaining the mark points through a vision system, the coordinates of the upper left corner of the DIE's adhesive application area can be determined using their fixed size and position parameters. This is the deviation (△Xp, △Yp) between the second specific identification point and the mark point's position coordinates (this deviation value is determined after the wafer specifications and design are completed). (The values ​​are already determined). In this step, the coordinates of the center of the vision camera in the world coordinate system are (Xj, Yj). The coordinates of the mark on the wafer in the coordinate system of the vision camera / vision system, with the center of the vision camera as the origin, are (Xm, Ym). Then, the coordinates of the mark in the world coordinate system of the machine are (Xj+Xm, Yj+Ym). Then, the coordinates of the second specific marker point on the dispensing area on the wafer are obtained (Xj+Xm+△Xp, Yj+Ym+△Yp). It should be noted that the second specific marker point is the boundary corner of the dispensing area. In this embodiment, it is set to the upper left corner of the chip DIE (i.e., the corner of the chip DIE). Figure 2 (The location of marker point C in the image).

[0042] Of course, due to the special nature of wafers, it is difficult to accurately position them on the dispensing platform during placement. Therefore, the initial position of the wafer on the dispensing platform is relatively arbitrary (the alignment position on the dispensing platform is set as the origin position of the dispensing platform for easy understanding. This origin position is obtained by the system in advance. After the wafer is placed on the dispensing platform, it will be offset or deflected within a certain range relative to the preset dispensing pattern). Therefore, the wafer mark obtained by the vision camera is somewhat skewed from the preset dispensing pattern. Therefore, before obtaining the accurate mark coordinates in the above steps, this embodiment also includes a step whereby the vision camera pre-captures the wafer and analyzes the wafer image to obtain the initial wafer mark coordinates. For example, the obtained mark position information includes (Xcs1, Ycs1) and Ccs (Ccs is the wafer deflection angle, which the work platform can compensate for by rotation. The specific rotation and compensation of the work platform are no different from the prior art, and will not be described in detail here). It should be noted that there are often more than two marks on the wafer. Here, it is necessary to analyze and calculate the deviation angle between the wafer and the work platform coordinate system based on the obtained mark position. The deflection angle Ccs can be calculated by the vision camera and vision system first. Then, the dispensing platform compensates for the deflection angle so that the coordinate system of the wafer coincides with the coordinate system of the dispensing platform. Subsequently, the vision camera captures the image again to obtain the accurate wafer mark coordinates (Xj+Xm, Yj+Ym). (It should be noted that in order to obtain the deflection angle of the wafer, two markers are required. After obtaining the deflection angle Ccs and the dispensing platform is rotated to compensate for the angle, you only need to select and set the coordinates of one of the marker points as the coordinates of the wafer to avoid confusion.)

[0043] S2D: Wafer alignment; the dispensing platform moves the wafer to adjust the wafer mark coordinates. Figure 2 The location of the marker point B coincides with the coordinates of the preset alignment point (Xym, Yym). The distance the dispensing platform moves the wafer is the difference between the wafer marker coordinates (Xj+Xm, Yj+Ym) and the preset alignment point coordinates (Xym, Yym). Since the preset dispensing pattern and the wafer are located in the same world coordinate system, when the wafer marker coordinates coincide with the preset alignment point coordinates (Xym, Yym), the wafer's chip die coincides with the dispensing area of ​​the preset dispensing pattern, thus completing wafer alignment.

[0044] S3: Adhesive Spraying Alignment; After wafer alignment in step S2, the inkjet head only needs to be moved until its zero-point coordinates coincide with the upper left corner (i.e., the adhesive spraying head alignment point) of the rectangular boundary of the preset adhesive spraying pattern (Xy, Yy). This achieves inkjet head adhesive spraying alignment. This also includes determining the chip adhesive spraying area, which can be determined by the positional relationship between the specific second marker point and the adhesive spraying head alignment point. The inkjet head zero-point coordinates have already been determined in step S1 (i.e., the coordinates of the specific marker point). By aligning the inkjet head zero-point coordinates with the upper left corner of the rectangular boundary of the preset adhesive spraying pattern, the required X and Y direction movement data for the inkjet head to move to that position can be calculated.

[0045] S4: Spraying adhesive; In principle, after the wafer mark coordinates coincide with the preset alignment point (Xym, Yym) coordinates, the second specific identification point of the DIE / chip will be aligned with the second specific identification point of the preset adhesive spraying pattern. Figure 2 If the corresponding point (Xyd, Yyd) of the marked point B coincides with the point position of the rectangle, then it is only necessary to determine the position based on the top left corner of the rectangle boundary. Figure 2 The location of the chip / DIE can be determined by measuring the distance between the coordinates (Xy, Yy) of the marker point D and the corresponding point (Xyd, Yyd). The printhead then sprays adhesive according to the preset adhesive pattern. The inkjet parameters are calculated as follows: the wafer size and chip size are measured using an optical microscope. The distance from the center of any marker point to the chip is measured, thus providing the dimensional parameters required for pattern drawing. The selected marker point is established as the origin by default, creating an XY coordinate system. The marker point coordinates are (0, 0). Boundary points X1 (2, 2), X2 (30, 2), and Y1 (2, 26) are measured. Therefore, the length d1 of the chip area = the algebraic difference between boundary points X1 and X2 on the X-axis = 28mm, and the width d2 of a single chip area = the algebraic difference between boundary points X1 and Y1 on the Y-axis = 24mm. That is, the length d1 of the chip area is 28mm, and the width d2 is 24mm. d1 and d2 are the physical dimensions of the chip and need to be converted to pixel dimensions. Pixel dimensions are calculated as d1 / 25.4 × horizontal DPI. The horizontal DPI is fixed by the number of 11 holes in the inkjet head (e.g., 360). Without adjusting the DPI, the horizontal single-row pixel size of the length d1 of a single chip area is 28 / 25.4×360=399px. This means that the number of pixels in the horizontal (length) direction of a single chip area is 399px, ensuring that the ink droplet placement of each pixel is consistent with the design and avoiding display defects. In this embodiment, further, to achieve the target weight for a single chip and thus meet the adhesive volume accuracy requirements, the required vertical (width) DPI can be adjusted to increase the number of inkjet strokes in the vertical direction. Specifically, this includes the following steps:

[0046] a. Calculate the total weight of a single horizontal line of ink droplets:

[0047] If the ink density is 1.02 g / ml, the volume of a single drop is 6 pl, the number of pixels per line (number of ink drops) is 399 px, and the weight w = ρ × v × number of ink drops per line (number of horizontal pixels).

[0048] That is: w = 1.02 g / ml × 6 × 10⁻⁶ 9 ml × 399 = 2.4 μg;

[0049] b. Calculate the number of rows required for vertical ink droplets:

[0050] If the total target weight of the chip area is 3.2 mg, the required number of rows = total target weight / weight per row.

[0051] That is: Required number of rows = 3.2mg × 10³μg / 2.4μg ≈ 1333px

[0052] c. Calculate the DPI of the vertical ink droplets:

[0053] If the width of a single vertical chip area is measured to be 24mm, then the width of the printed ink droplet is 24mm.

[0054] Vertical DPI = pixels × 25.4 / width d2 of a single bare chip area;

[0055] That is: Vertical DPI = 1333px × 25.4 / 24mm ≈ 1411.

[0056] After calculating the vertical DPI based on the total target weight, the chip areas corresponding to the horizontal and vertical DPIs are defined in the preset adhesive spraying pattern, with spacing between adjacent chip areas. Figure 2 In the preset adhesive pattern shown, the inkjet area and the blank area are different colors, such as the inkjet area being black and the blank area being white. Furthermore, each DPI of the inkjet area and the blank area is classified, with the DPI of the inkjet area being 1 and the DPI of the blank area being 2, which facilitates the identification by the inkjet control system.

[0057] S5: The adhesive spraying is finished, and the wafer is transferred to the next station.

[0058] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An inkjet needle alignment method and its dispensing alignment method, characterized in that: The method comprises the following steps S1: inkjet head alignment, comprising S1A: control the inkjet head to move from a preset origin coordinate to a printing position, and print a preset pattern; S1B: collect the pattern data formed in step S1A by a vision camera; S1C: analyze and process the pattern data to obtain a specific mark point coordinate of the preset pattern, and set the inkjet head zero point to coincide with the specific mark point coordinate; S1D: calculate the deviation value of the inkjet head zero point and the preset origin coordinate based on the algebraic operation of the printing position coordinate of the inkjet head and the specific mark point coordinate; S2: glue jet origin position acquisition, comprising: S2A: preset glue jet pattern; the preset glue jet pattern is provided with a glue jet head alignment point, a wafer mark alignment point and a chip alignment point; S2B: wafer image acquisition; place the wafer on the glue dispensing platform, and acquire the wafer image by the vision camera; S2C: obtain the mark coordinate of the wafer; analyze and process the wafer image to determine the coordinate position of the wafer mark; S2D: wafer alignment; control the glue dispensing platform to move the wafer so that the wafer mark coordinate coincides with the wafer mark alignment point coordinate in step S2A, and complete the wafer alignment; S3: glue jet alignment; control the inkjet head to move so that the inkjet head zero point determined in step S1 coincides with the glue jet head alignment point; S4: glue jet; control the inkjet head to perform glue jet operation according to the preset glue jet pattern.

2. The method of claim 1, wherein: The inkjet head zero point coordinate is obtained by compensating the deviation value by the preset origin coordinate.

3. The method of claim 1, wherein: The preset pattern is a rectangle, and the specific mark point is any corner of the rectangle.

4. The method of claim 1, wherein: Step S2C further comprises: calculating the deflection angle and X / Y direction deviation value of the wafer and the preset glue jet pattern based on the wafer mark coordinate; in step S2D, the glue dispensing platform rotates the wafer for compensation and translation compensation.

5. The method of claim 1, wherein: Step S2A or step S4 comprises the step of converting the preset glue jet pattern into pixel size.

6. The method of claim 1, wherein: The preset glue jet pattern comprises a rectangular boundary, the rectangular boundary is located at the periphery of the chip glue jet area, and any corner of the rectangular boundary is the glue jet head alignment point.

7. The method of claim 6, wherein: The preset glue jet pattern in step S2A comprises glue jet images of the same size and distribution as the chips on the wafer, wherein the area corresponding to the chips forms an inkjet area, and the remaining area in the rectangular boundary is a blank area.

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