A high-precision alignment method

Abstract

The present invention discloses a high-precision alignment method, comprising the following steps: S1, a pick-up head picks up a chip and flips 180 degrees; S2, a welding head absorbs the chip from the pick-up head; S3, the welding head moves to the top of a calibration sheet along with a first downward-looking visual device and a second downward-looking visual device, and the welding head moves horizontally to avoid the calibration sheet; S4, identifying the relative error between the visual center of the upward-looking vision and the visual center of the downward-looking vision; S5, the relative error between the marking point on the chip and the visual center of the first downward-looking visual device; S6, identifying the relative error between the marking point on the substrate and the visual center of the first downward-looking visual device; S7, calculating the spacing between the marking point on the chip and the marking point on the substrate; S8, performing position compensation; S9, high-precision bonding. Compared with the prior art, the present invention uses a high-precision position sensor in conjunction with multiple visual detection devices to achieve chip position calibration, effectively improving bonding accuracy.

Description

Technical Field

[0001] The invention belongs to the field of chip bonding, and in particular relates to a high-precision alignment method. Background Art

[0002] Flip-chip welding equipment is mainly used for the flip-chip welding process in the manufacture of large-scale integrated circuit devices. It completes the direct interconnection and bonding of the chip and the substrate, making the package have more superior high-frequency, low-latency, and low-crosstalk circuit characteristics, and can effectively improve the reliability of assembly interconnection of circuits, components or systems.

[0003] When the chip is bonded, the bonded chip is pressed and bonded to the substrate, thereby completing the flip-chip bonding process of the chip. In the prior art, when calculating and compensating the chip position through multiple visual inspection devices (upward vision, downward vision), it is usually necessary to set multiple marking points on the calibration sheet. Different visual inspection devices correspond to different marking points, which makes the calculation of position compensation more complicated, affecting the position compensation effect, and further affecting the bonding accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision alignment method, which uses a high-precision position sensor in conjunction with multiple visual inspection devices to achieve chip position calibration and effectively improve bonding accuracy.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a high-precision alignment method, comprising the following steps:

[0006] S1. The first visual inspection component identifies the outline of the chip, and the pickup head moves to the top of the chip, picks up the chip downward, and then turns the chip 180 degrees after rising;

[0007] S2. The welding head picks up the chip from the pickup head, and the marking point on the chip , Mark Point Direction downwards;

[0008] S3, the welding head moves with the first downward visual device and the second downward visual device to above the calibration sheet, and the welding head moves horizontally to avoid the calibration sheet;

[0009] S4, there are marking points on the calibration sheet , , the first downward vision device identifies the marker point , the second downward vision device identifies the marker point A first upward visual device and a second upward visual device are arranged below the calibration sheet. The first upward visual device identifies the marking point. , the second upward vision device recognizes the marking point , and obtain the relative error between the visual center of the first downward-looking visual device and the visual center of the first upward-looking visual device and the error between the visual center of the second downward-looking visual device and the visual center of the second downward-looking visual device At this time, the high-precision position sensor on the second downward-looking visual device records the first position data of the welding head, and the first position data includes the position of the welding head in the XYZ direction;

[0010] S5. The calibration piece moves horizontally to avoid the chip. At the same time, the welding head moves horizontally so that the chip moves above the first upward vision device and the second upward vision device. The first upward vision device recognizes the marking point. , the second upward vision device identifies the mark point , get the marked point Relative error with the visual center of the first upward vision device And marking points Relative error with the visual center of the second upward vision device , so as to calculate the marking point Relative error with the visual center of the first downward vision device And marking points Relative error with the visual center of the second downward vision device ;

[0011] S6, the welding head moves to the top of the substrate along with the first downward vision device and the second downward vision device, and then the welding head moves horizontally to make way, and the first downward vision device recognizes the marking point on the substrate , the second downward vision device recognizes the marking points on the substrate , get the marked point Relative error with the visual center of the first downward vision device And marking points Relative error with the visual center of the second downward vision device ;

[0012] S7, the welding head moves to the top of the substrate, at this time, the high-precision position sensor on the second downward vision device records the second position data of the welding head, and the relative error is calculated. and relative error Calculate the marker points With markers Spacing , according to the relative error and relative error Calculate the marker points With markers Spacing ;

[0013] S8, welding head according to the calculated spacing and spacing , perform XY motion to achieve position compensation;

[0014] S9. After the chip is aligned with the substrate, the welding head descends along the Z axis to bond the chip and the substrate.

[0015] As a further description of the above technical solution:

[0016] In step S4, the welding head is lowered along the Z axis with the first downward vision device and the second downward vision device, so that the chip under the welding head and the calibration piece are at the same height, and then the relative error is identified. , .

[0017] As a further description of the above technical solution:

[0018] In step S7, the distance is calculated and spacing Previously, the position offset of the welding head was calculated based on the first position data and the second position data, and the welding head performed height compensation and XY position compensation based on the position offset.

[0019] As a further description of the above technical solution:

[0020] In step S5, the relative error The calculation formula is .

[0021] As a further description of the above technical solution:

[0022] In step S7, the spacing The calculation formula is .

[0023] As a further description of the above technical solution:

[0024] In step S5, the relative error The calculation formula is .

[0025] As a further description of the above technical solution:

[0026] In step S7, the spacing The calculation formula is .

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. In the present invention, during the chip bonding process, since the high-precision position sensor can detect the error caused by the movement of the welding head and compensate for it, when the upward vision and the downward vision use the calibration sheet to calibrate the chip position, the relative upward vision and the downward vision use the same marking point on the calibration sheet to calculate the relative error between the visual center of the upward vision and the visual center of the downward vision, and then identify the relative error between the marking point on the chip and the visual center of the first upward vision device, and obtain the relative error between the marking point on the chip and the visual center of the first downward vision device, and then identify the relative error between the marking point on the substrate and the visual center of the first downward vision device, and finally calculate the distance between the marking point on the chip and the marking point on the substrate, so as to perform position compensation and achieve high-precision bonding.

[0029] 2. In the present invention, the number of marking points on the calibration sheet can be effectively reduced, the calculation of position compensation can be simplified, and the bonding accuracy can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 Schematic diagram of step S3 in a high-precision alignment method.

[0032] Figure 2 Schematic diagram of step S4 in a high-precision alignment method.

[0033] Figure 3 Schematic diagram of step S5 in a high-precision alignment method.

[0034] Figure 4 Schematic diagram of step S6 in a high-precision alignment method.

[0035] Figure 5 Schematic diagram of step S7 in a high-precision alignment method.

[0036] Figure 6 Schematic diagram of step S9 in a high-precision alignment method.

[0037] Legend:

[0038] 1. Chip; 2. Welding head; 3. Calibration sheet; 4. Substrate; 5. High-precision position sensor. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] See also Figure 1-6 The present invention provides a technical solution: a high-precision alignment method, comprising the following steps:

[0042] S1, the first visual inspection component identifies the outline of chip 1, the pickup head moves to the top of chip 1, picks up chip 1 downward, and turns chip 1 180 degrees after rising;

[0043] S2, welding head 2 picks up chip 1 from the pick-up head, and the marking point on chip 1 , Mark Point Direction downwards;

[0044] S3, the welding head 2 moves to above the calibration sheet 3 along with the first downward-looking visual device and the second downward-looking visual device, and the welding head 2 moves horizontally to avoid the calibration sheet 3;

[0045] S4, calibration sheet 3 is provided with marking points , , the first downward vision device identifies the marker point , the second downward vision device identifies the marker point A first upward visual device and a second upward visual device are arranged below the calibration sheet 3. The first upward visual device identifies the marking point , the second upward vision device recognizes the marking point , and obtain the relative error between the visual center of the first downward-looking visual device and the visual center of the first upward-looking visual device and the error between the visual center of the second downward-looking visual device and the visual center of the second downward-looking visual device , At this time, the second downward-looking high-precision position sensor 5 on the visual device records the first position data of the welding head 2, the first position data includes the position of the welding head 2 in the XYZ direction;

[0046] S5, the calibration piece 3 moves horizontally to avoid, and the welding head 2 moves horizontally at the same time, so that the chip 1 moves to the top of the first upward visual device and the second upward visual device (the original calibration piece 3 position), and the first upward visual device recognizes the mark point , the second upward vision device identifies the mark point , get the marked point Relative error with the visual center of the first upward vision device And marking points Relative error with the visual center of the second upward vision device , so as to calculate the marking point Relative error with the visual center of the first downward vision device And marking points Relative error with the visual center of the second downward vision device ;

[0047] S6, the welding head 2 moves to the top of the substrate 4 along with the first downward visual device and the second downward visual device, and then the welding head 2 moves horizontally to make way, and the first downward visual device recognizes the marking point on the substrate 4 , the second downward vision device recognizes the marking point on the substrate 4 , get the marked point Relative error with the visual center of the first downward vision device And marking points Relative error with the visual center of the second downward vision device ;

[0048] S7, the welding head 2 moves to the top of the substrate 4, at this time, the high-precision position sensor 5 on the second downward vision device records the second position data of the welding head 2, which, like the first position data, includes the position of the welding head in the XYZ direction, and the relative error is calculated. and relative error Calculate the marker points With markers Spacing , according to the relative error and relative error Calculate the marker points With markers Spacing ;

[0049] S8, a high-precision motion platform is provided on the back of the welding head 2, and the welding head 2 moves according to the calculated spacing. and spacing , perform XY motion to achieve position compensation;

[0050] S9. After the chip 1 is aligned with the substrate 4, the bonding head 2 descends along the Z axis to bond the chip 1 and the substrate 4.

[0051] In step S4, the welding head 2 is lowered along the Z axis along with the first downward visual device and the second downward visual device, so that the chip 1 under the welding head 2 and the calibration sheet 3 are at the same height, and then the relative error is identified. , .

[0052] In step S7, the distance is calculated and spacing Previously, the position offset of the welding head 2 was calculated based on the first position data and the second position data, and the welding head 2 performed height compensation and XY position compensation based on the position offset to avoid position offset caused by the movement of the welding head 2, thereby ensuring the spacing and spacing The accuracy of calculation can ensure the position compensation effect and bonding accuracy.

[0053] In calculating the relative error ,spacing , relative error and spacing When calculating the relative error, we consider that the two sets of visual center positions may be in opposite directions, and there is superposition and subtraction in the relative error calculation. Therefore, the default relative position calculation uses the upward visual center as the calculation reference point, so that the direction problem is converted into positive and negative values, which can be subtracted during calculation. Therefore, the specific calculation formula is as follows:

[0054] In step S5, the relative error The calculation formula is .

[0055] In step S7, the spacing The calculation formula is .

[0056] In step S5, the relative error The calculation formula is .

[0057] In step S7, the spacing The calculation formula is .

[0058] The marking points on the calibration sheet 3 are photoetching points with a precision of nanometer level.

[0059] Working principle: During the chip bonding process, since the high-precision position sensor can detect the error caused by the movement of the welding head and compensate for it, when the upward vision and downward vision use the calibration sheet to calibrate the chip position, the relative upward vision and downward vision use the same mark point on the calibration sheet to calculate the relative error between the visual center of the upward vision and the visual center of the downward vision, and then identify the relative error between the mark point on the chip and the visual center of the first upward vision device, and obtain the relative error between the mark point on the chip and the visual center of the first downward vision device, and then identify the relative error between the mark point on the substrate and the visual center of the first downward vision device, and finally calculate the distance between the mark point on the chip and the mark point on the substrate, so as to perform position compensation and achieve high-precision bonding. During calibration, the number of mark points on the calibration sheet can be effectively reduced, the calculation of position compensation can be simplified, and the bonding accuracy can be improved.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high-precision alignment method, characterized in that: The following steps are involved: S1, a first visual inspection component identifies the outline of the chip (1), a pick-up head moves to the top of the chip (1), picks up the chip (1) downward, and after rising, turns the chip (1) 180 degrees; S2, the welding head (2) picks up the chip (1) from the pick-up head, with the marking point B1 and the marking point B2 on the chip (1) facing downwards; S3, the welding head (2) moves to above the calibration sheet (3) along with the first downward-looking visual device and the second downward-looking visual device, and the welding head (2) moves horizontally to avoid the calibration sheet (3); S4, the calibration sheet (3) is provided with marking points A1 and A2, a first downward-looking visual device recognizes the marking point A1, and a second downward-looking visual device recognizes the marking point A2, a first upward-looking visual device and a second upward-looking visual device are provided below the calibration sheet (3), the first upward-looking visual device recognizes the marking point A1, and the second upward-looking visual device recognizes the marking point A2, and a relative error between the visual center of the first downward-looking visual device and the visual center of the first upward-looking visual device is obtained and the error between the visual center of the second downward-looking visual device and the visual center of the second downward-looking visual device At this time, the high-precision position sensor (5) on the second downward-looking visual device records the first position data of the welding head (2), wherein the first position data includes the position of the welding head (2) in the XYZ direction; S5, the calibration sheet (3) moves horizontally to avoid, and the welding head (2) moves horizontally at the same time, so that the chip (1) moves to above the first upward visual device and the second upward visual device, the first upward visual device identifies the marking point B1, and the second upward visual device identifies the marking point B2, and obtains the relative error δ between the marking point B1 and the visual center of the first upward visual device B1 And the relative error δ between the marking point B2 and the visual center of the second upward vision device B2 , thereby calculating the relative error A1B1 between the marking point B1 and the visual center of the first downward-looking visual device and the relative error A2B2 between the marking point B2 and the visual center of the second downward-looking visual device; S6, the welding head (2) moves to the top of the substrate (4) along with the first downward visual device and the second downward visual device, and then the welding head (2) moves horizontally to make way, the first downward visual device identifies the marking point C1 on the substrate (4), and the second downward visual device identifies the marking point C2 on the substrate (4), and obtains the relative error between the marking point C1 and the visual center of the first downward visual device And the relative error between the marking point C2 and the visual center of the second downward vision device S7, the welding head (2) moves to above the substrate (4), at which time the high-precision position sensor (5) on the second downward-looking visual device records the second position data of the welding head (2), and calculates the relative error A1B1 and the relative error Calculate the distance B1C1 between the marking point B1 and the marking point C1, based on the relative error A2B2 and the relative error Calculate the distance B2C2 between the marking point B2 and the marking point C2; S8, the welding head (2) performs XY movement according to the calculated spacing B1C1 and spacing B2C2 to achieve position compensation; S9, after the chip (1) is aligned with the substrate (4), the bonding head (2) descends along the Z axis to bond the chip (1) and the substrate (4); In the step S7, before calculating the spacing B1C1 and the spacing B2C2, the position offset of the welding head (2) is calculated according to the first position data and the second position data, and the welding head (2) performs height compensation and XY position compensation according to the position offset.

2. A high-precision alignment method according to claim 1, characterized in that: In step S4, the welding head (2) is lowered along the Z axis along with the first downward visual device and the second downward visual device, so that the chip (1) and the calibration sheet (3) below the welding head (2) are at the same height, and then the relative error is identified.

3. A high-precision alignment method according to claim 1, characterized in that: In step S5, the calculation formula of the relative error A1B1 is:

4. A high-precision alignment method according to claim 3, characterized in that: In step S7, the calculation formula of the spacing B1C1 is:

5. A high-precision alignment method according to claim 1, characterized in that: In step S5, the calculation formula of the relative error A2B2 is:

6. A high-precision alignment method according to claim 5, characterized in that: In step S7, the calculation formula of the spacing B2C2 is:

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