TWI874015B - Package structure and manufacturing method thereof - Google Patents

Abstract

A package structure comprises a die, a substrate and a first soldering section, the die has a first soldering pad provided thereon, the substrate has a second soldering pad provided thereon, and the first soldering section is connected between the first soldering pad and the second soldering pad. The die further comprises a first auxiliary soldering pad provided thereon, the substrate further comprises a second auxiliary soldering pad provided thereon, and the package structure further comprises a second soldering section which is connected between the first auxiliary soldering pad and the second auxiliary soldering pad. The first auxiliary soldering pad is located at a first pre-set position on the die, where the distance between the first pre-set position and the center of gravity of the die is the longest compared to other positions on the die other than the first pre-set position. The present package structure improves self-alignment between the die and the substrate, thus the packaging accuracy of the die and the substrate can be improved. The present invention also discloses a manufacturing method of the package structure.

Description

Packaging structure and preparation method thereof

The present invention relates to the field of electronic component packaging technology, and specifically to a packaging structure and a preparation method thereof.

With the rapid development of the semiconductor industry, the application scope of packaging technology is becoming increasingly wide, and the packaging forms are becoming more diverse. Among them, flip-chip technology, also known as "flip chip packaging" or "flip chip packaging method", is both a chip interconnection technology and a more ideal chip bonding technology.

When connecting the substrate and the die, the previous technology usually first applies solder paste to the pads of the substrate and the die, and then heats the solder paste by reflow soldering to melt the solder paste and connect the substrate and the die after solidification. However, this connection method has a small offset of the die relative to the substrate, which cannot meet the requirements of high-precision die packaging in some scenarios.

In view of the above, it is necessary to propose a packaging structure and its preparation method to improve the packaging accuracy of the die and substrate.

In a first aspect, an embodiment of the present invention provides a packaging structure, including a die, a substrate, and a first welding portion, wherein the die is provided with a first welding pad, the substrate is provided with a second welding pad corresponding to the first welding pad, the first welding portion is connected between the first welding pad and the second welding pad, the die is further provided with a first auxiliary welding pad spaced apart from the first welding pad, the substrate is further provided with a second auxiliary welding pad spaced apart from the second welding pad, Auxiliary pad, the package structure further includes a second welding portion, the second auxiliary pad is arranged corresponding to the first auxiliary pad, and the second welding portion is connected between the first auxiliary pad and the second auxiliary pad; the first auxiliary pad is arranged at a first preset position on the die, and compared with other positions on the die except the first preset position, the distance between the first preset position and the center of gravity of the die is the longest.

In the above-mentioned packaging structure, a first auxiliary pad is arranged on the die at a spacing with the first pad, and a second auxiliary pad is arranged on the substrate at a spacing with the second pad and corresponding to the first auxiliary pad. When the substrate and the die are soldered by reflow soldering, the solder between the first auxiliary pad and the second auxiliary pad and between the first pad and the second pad will melt, that is, the first soldering portion and the second soldering portion will melt, and the melted first soldering portion and the second soldering portion can act on the first soldering pad and the first auxiliary soldering pad respectively to drive the die to rotate relative to the substrate until the first soldering pad is aligned with the second soldering pad. Since the first auxiliary pad is located at the first preset position on the die, and compared with other positions on the die except the first preset position, the distance between the first preset position and the center of gravity of the die is the longest, the first auxiliary pad located at the first preset position can provide the maximum rotational torque for the die to rotate relative to the substrate, thereby improving the self-alignment ability between the die and the substrate, and further improving the packaging accuracy of the die and the substrate, and to a certain extent, it can also expand the packaging use scenarios of the die.

In a second aspect, an embodiment of the present invention further provides a method for preparing a packaging structure, the method comprising the following steps: etching a crystal grain to form a first pad and a first auxiliary pad spaced apart from the first pad on the crystal grain, wherein the first auxiliary pad is formed at a first preset position on the crystal grain, and compared with other positions on the crystal grain except the first preset position, the distance between the first preset position and the center of gravity of the crystal grain is the longest; etching a substrate to form a second pad and a second auxiliary pad spaced apart from the second pad on the substrate; coating the second pad and the second auxiliary pad with solder; The crystal grain is covered on the substrate, and the first pad is aligned with the second pad and attached to the solder on the second pad, and the first auxiliary pad is aligned with the second auxiliary pad and attached to the solder on the second auxiliary pad; the solder is heated to melt the solder between the first pad and the second pad, and the solder between the first auxiliary pad and the second auxiliary pad is melted, and the melted solder can act on the first pad and the first auxiliary pad to drive the crystal grain to rotate relative to the substrate until the first pad is aligned with the second pad.

The method for preparing the package structure is as follows: first, a first pad and a first auxiliary pad spaced apart from the first pad are formed on the die by etching the die; then, a second pad and a second auxiliary pad spaced apart from the second pad are formed on the substrate by etching the substrate; then, solder is coated on the second pad and the second auxiliary pad; then, the die is covered on the substrate, and the first pad is aligned with the second pad and attached to the second pad. The solder on the auxiliary pad and the solder that makes the first auxiliary pad align with the second auxiliary pad and adheres to the second auxiliary pad; finally, the solder is heated to melt the solder between the first pad and the second pad, and the solder between the first auxiliary pad and the second auxiliary pad is melted, and the molten solder can act on the first pad and the first auxiliary pad to drive the die to rotate relative to the substrate until the first pad is aligned with the second pad. Since the first auxiliary pad is formed at the first preset position on the die, and compared with other positions on the die except the first preset position, the distance between the first preset position and the center of gravity of the die is the longest, the first auxiliary pad located at the first preset position can provide the maximum rotational torque for the die to rotate relative to the substrate, thereby improving the self-alignment ability between the die and the substrate, and further improving the packaging accuracy of the die and the substrate, and to a certain extent, it can also expand the packaging use scenarios of the die.

100:Packaging structure

10: Grain

11: First default position

12, 22: Other locations

20: Substrate

21: Second default position

30: First welding section

40: Second welding section

50: First pad

60: First auxiliary pad

70: Second pad

80: Second auxiliary pad

O ₁ , O ₂ , O ₃ , O ₄ : center of gravity

Figure 1 is a schematic diagram of the packaging structure proposed in one embodiment of the present invention.

Figure 2 is a schematic diagram of the cross-sectional structure of the package structure shown in Figure 1 along line II-II.

FIG3 is a schematic diagram of the structure of the die, the first pad and the first auxiliary pad of the package structure proposed in one embodiment of the present invention.

FIG4 is a schematic diagram of the structure of the die, the first pad and the first auxiliary pad of the package structure proposed in another embodiment of the present invention.

FIG5 is a schematic diagram of the structure of the die, the first pad and the first auxiliary pad of the package structure proposed in another embodiment of the present invention.

FIG6 is a schematic diagram of the partial structure of the substrate, the second auxiliary pad and the second pad of the package structure proposed in one embodiment of the present invention.

FIG7 is a schematic diagram of the structure of a partial substrate, a second auxiliary pad, and a second pad of a package structure proposed in another embodiment of the present invention.

FIG8 is a schematic diagram of the structure of a partial substrate, a second auxiliary pad, and a second pad of a packaging structure proposed in another embodiment of the present invention.

FIG9 is a flow chart of a method for preparing a packaging structure proposed in an embodiment of the present invention.

The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the attached drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the attached drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

The specific implementation of the present invention is further described in detail below with reference to the attached drawings.

Please refer to FIG. 1 and FIG. 2 , the embodiment of the present invention proposes a packaging structure 100, including a die 10, a substrate 20, a first welding portion 30 and a second welding portion 40.

The die 10 is provided with a first pad 50 and a first auxiliary pad 60, and the first auxiliary pad 60 is spaced apart from the first pad 50. The substrate 20 is provided with a second pad 70 and a second auxiliary pad 80, and the second auxiliary pad 80 is spaced apart from the second pad 70, and the second pad 70 is disposed corresponding to the first pad 50, the first welding portion 30 is connected between the first pad 50 and the second pad 70, the second auxiliary pad 80 is disposed corresponding to the first auxiliary pad 60, and the second welding portion 40 is connected between the first auxiliary pad 60 and the second auxiliary pad 80. Please refer to FIG. 3 , the first auxiliary pad 60 is disposed at the first preset position 11 on the die 10. Compared with the first auxiliary pad 60 at other positions on the die 10 (such as other positions 12 shown as an example in FIG. 3 , corresponding to the area enclosed by the dotted frame and one side of the die 10), except for the first preset position 11 (the area enclosed by the dotted frame and two sides of the die 10 in the figure), the distance between the first auxiliary pad 60 at the first preset position 11 and the center of gravity _O1 of the die 10 is the longest. It can be understood that the other positions 12 in FIG. 3 are merely examples of positions different from the first preset position 11, and are not intended to limit the specific positions in this embodiment. Moreover, the first preset position 11 is viewed as a whole, that is, the components at the first preset position 11 as a whole are at the longest distance from the center of gravity _O1 of the die 10 compared to the components arranged at other positions on the die 10.

The package structure 100 is provided with a first auxiliary pad 60 spaced apart from the first pad 50 on the die 10, and a second auxiliary pad 80 spaced apart from the second pad 70 and corresponding to the first auxiliary pad 60 on the substrate 20. When the substrate 20 and the die 10 are soldered by reflow soldering, the first auxiliary pad 60 and the second auxiliary pad 80 are soldered together. The solder between the first pad 50 and the second pad 70 will melt, that is, the first soldering portion 30 and the second soldering portion 40 will melt, and the melted first soldering portion 30 and the second soldering portion 40 can act on the first pad 50 and the first auxiliary pad 60 respectively to drive the die 10 to rotate relative to the substrate 20 until the first pad 50 is aligned with the second pad 70. Since the first auxiliary pad 60 is disposed at the first preset position 11 on the die 10, and compared with the first auxiliary pads 60 at other positions on the die 10 except the first preset position 11, the distance between the first auxiliary pad 60 at the first preset position 11 and the center of gravity _O1 of the die 10 is the longest, the first auxiliary pad 60 located at the first preset position 11 can provide the maximum rotational torque for the die 10 to rotate relative to the substrate 20, thereby improving the self-alignment capability between the die 10 and the substrate 20, and further improving the packaging accuracy of the die 10 and the substrate 20, and to a certain extent, it can also expand the packaging use scenarios of the die 10.

The die 10 is a single bare chip that has not been packaged after the wafer has been thinned and cut, such as a light-emitting diode die 10. The material of the substrate 20 is an epoxy copper-clad circuit board (PCB), a polyimide (PI) copper-clad circuit board, a flexible circuit board (FPC) or a polyethylene terephthalate (PET) circuit board. The first welding portion 30 and the second welding portion 40 are both solidified tin, silver, indium or tin alloy. For example, the material of the first welding portion 30 and the second welding portion 40 is tin.

Please refer to FIG. 2 and FIG. 3 , the die 10 is a square structure. There are a plurality of first pads 50, for example, 13. Among the plurality of first pads 50, one first pad 50 is located in the central area of the die 10, and the remaining plurality of first pads 50 are arranged around the first pad 50 located in the central area of the die 10, wherein the bottom surface area of the first pad 50 located in the central area of the die 10 is larger, and the bottom surface areas of the remaining plurality of first pads 50 are equal.

The material of the first solder pad 50 is one of gold, copper, silver, aluminum and tin. In this way, the electrical conductivity and connection effect of the first solder pad 50 can be guaranteed.

In this embodiment, there are four first auxiliary pads 60, which are respectively arranged at the four corners of the die 10. In this way, the first auxiliary pads 60 are distributed more evenly on the die 10, and when the solder melts, it can provide a more consistent force for the die 10 to rotate relative to the substrate 20.

The material of the first auxiliary pad 60 is one of gold, copper, silver, aluminum and tin. In this way, the conductive performance and connection effect of the first auxiliary pad 60 can be guaranteed.

The first pad 50 and the first auxiliary pad 60 are at the same height relative to the surface of the die 10. In this way, the flatness of the surface of the die 10 after welding can be guaranteed.

The first pad 50 and the first auxiliary pad 60 are made of the same material. In this way, the first pad 50 and the first auxiliary pad 60 can be made on the die 10 at the same time, and the production of the first pad 50 and the first auxiliary pad 60 is time-saving and efficient.

The shape of the first auxiliary pad 60 is rectangular. The ratio of the area L1 of the first auxiliary pad 60 to the area L2 of the first pad 50 is in the range of 0.01-5. In this way, it can be ensured that the area of the auxiliary pad provides sufficient rotation torque, but is not too large to occupy the surface space of the die 10.

Please refer to FIG. 4 , the first auxiliary pad 60 is in the shape of a long strip, wherein the center of gravity O ₃ of at least two first auxiliary pads 60 located at two opposite corners in the diagonal direction of the die 10 and the center of gravity O ₁ of the first pad 50 located in the central area of the die 10 are all on a straight line. For example, there are two first auxiliary pads 60 located at two opposite corners in the diagonal direction of the die 10. In this way, the first auxiliary pads 60 at the corners of the die 10 can provide the maximum rotational torque during welding.

The minimum spacing value between the first pad 50 and the first auxiliary pad 60 is A. There are multiple first pads 50, and the spacing value between any two of the multiple first pads 50 is B. The ratio of A to B is in the range of 0.1-3. In this way, it can be ensured that the first pad 50 and the first auxiliary pad 60 will not be connected due to the melting of the solder during the welding process, thereby preventing a short circuit from occurring inside the die 10 or adversely affecting the self-alignment effect.

Please refer to Figure 5. The shape of the first auxiliary pad 60 is circular. In order to avoid short circuit of the components on the die 10, the distance S1 between the first auxiliary pad 60 and the edge of the die 10 is less than or equal to 3mm. When the distance S1 between the first auxiliary pad 60 and the edge of the die 10 is greater than 3mm, the rotation torque generated by the auxiliary pad cannot be maximized. In addition, when the gap between the first auxiliary pad 60 and the edge of the die 10 is less than or equal to 3mm, the first auxiliary pad 60 at the edge is not easily peeled off when the die 10 is cut.

Please refer to FIG. 2 and FIG. 6. The substrate 20 shown in FIG. 6 is a partial structure of the substrate 20 in FIG. 1. The partial structure is square and is arranged corresponding to the die 10. In the substrate 20 shown in FIG. 6, there are a plurality of second pads 70, for example, 13, one of which is located in the central area of the substrate 20, and the remaining second pads 70 are arranged around the second pad 70 located in the central area of the substrate 20, wherein the bottom surface area of the second pad 70 located in the central area of the substrate 20 is larger, and the bottom surface areas of the remaining second pads 70 are equal.

The material of the second solder pad 70 is one of gold, copper, silver, aluminum and tin. In this way, the electrical conductivity and connection effect of the second solder pad 70 can be guaranteed.

In this embodiment, there are four second auxiliary pads 80, which are respectively disposed at four corners of the substrate 20. In this way, the second auxiliary pads 80 are distributed more evenly on the substrate 20, so as to correspond to the four first auxiliary pads 60 respectively.

The material of the second auxiliary pad 80 is one of gold, copper, silver, aluminum and tin. In this way, the conductive performance and connection effect of the second auxiliary pad 80 can be guaranteed.

The second solder pad 70 and the second auxiliary solder pad 80 are at the same height relative to the surface of the substrate 20. In this way, the flatness of the surface of the substrate 20 after soldering can be guaranteed.

The second solder pad 70 and the second auxiliary solder pad 80 are made of the same material. In this way, the second solder pad 70 and the second auxiliary solder pad 80 can be manufactured on the substrate 20 at the same time, and the manufacturing of the second solder pad 70 and the second auxiliary solder pad 80 is time-saving and efficient.

The second auxiliary solder pad 80 is disposed at a second preset position 21 on the substrate 20, and the second preset position 21 is disposed corresponding to the first preset position 11 in FIG. 2 .

In this embodiment, the shape of the second auxiliary pad 80 is a rectangle. The ratio of the area L3 of the second auxiliary pad 80 to the area L4 of the second pad 70 is in the range of 0.01-5. In this way, it can be ensured that the area of the auxiliary pad provides sufficient rotational torque, but is not too large to occupy the surface space of the die 10.

Please refer to FIG. 7 , the second auxiliary pad 80 is in the shape of a long strip, wherein the center of gravity O ₄ of at least two second auxiliary pads 80 located at two opposite corners in the diagonal direction of the substrate 20 and the center of gravity O ₂ of the second pad 70 located in the central area of the substrate 20 are all on a straight line. For example, there are two second auxiliary pads 80 located at two opposite corners in the diagonal direction of the substrate 20. In this way, the corners of the die 10 can have the maximum rotational torque during welding.

The minimum spacing between the second pad 70 and the second auxiliary pad 80 is C. There are multiple second pads 70, and the spacing between any two of the multiple second pads 70 is D. The ratio of C to D is in the range of 0.1-3. In this way, it can be ensured that the second pad 70 and the second auxiliary pad 80 will not be connected due to the melting of the solder during the welding process, thereby preventing a short circuit from occurring inside the substrate 20 or adversely affecting the self-alignment effect.

Please refer to FIG8 . The second auxiliary pad 80 is circular in shape. In order to avoid short circuit of components on the substrate 20, the distance S2 between the second auxiliary pad 80 and the edge of the substrate 20 is less than or equal to 3 mm. When the distance S2 between the second auxiliary pad 80 and the edge of the substrate 20 is greater than 3 mm, the distance between the second pad 70 and the second auxiliary pad 80 is too small, which may cause a short circuit between the second pad 70 and the second auxiliary pad 80 due to melting of the solder during welding. In addition, when the gap between the second auxiliary pad 80 and the edge of the substrate 20 is less than or equal to 3 mm, the second auxiliary pad 80 at the edge is not easily peeled off when the substrate 20 is cut.

The shape of the first auxiliary pad 60 (as shown in FIG. 3 ) is the same as the shape of the second auxiliary pad 80 (as shown in FIG. 6 ). In this way, the contact area between the first auxiliary pad 60 and the second auxiliary pad 80 is larger, which can ensure that the first auxiliary pad 60 and the second auxiliary pad 80 are completely attached together.

The shape of the first pad 50 (as shown in FIG. 3 ) is the same as the shape of the second pad 70 (as shown in FIG. 6 ). Thus, the contact area between the first pad 50 and the second pad 70 is larger, which can ensure that the first pad 50 and the second pad 70 are completely attached together.

In some embodiments, the first auxiliary pad 60 may not be electrically connected to the circuit in the die 10, and the second auxiliary pad 80 may not be electrically connected to the circuit in the substrate 20. In some embodiments, the first auxiliary pad 60 may also serve as a circuit contact of the die 10, and the second auxiliary pad 80 may also serve as a circuit contact of the substrate 20.

Please refer to Figure 9. The embodiment of the present invention also provides a method for preparing a packaging structure 100, comprising the following steps:

S210, etching the die 10 to form a first pad 50 and a first auxiliary pad 60 spaced apart from the first pad 50 on the die 10, wherein the first auxiliary pad 60 is formed at a first preset position 11 on the die 10, and compared with other positions on the die 10 except the first preset position 11 (such as other positions 12 shown as an example in FIG. 3 ), the distance between the first preset position 11 and the center of gravity _O1 of the die 10 is the longest.

The substrate 20 is made of a copper-coated epoxy circuit board (PCB), a copper-coated polyimide (PI) circuit board, a flexible circuit board (FPC) or a polyethylene terephthalate (PET) circuit board. The die 10 is a single bare chip that is not packaged after the wafer is thinned and cut, such as a light-emitting diode die 10. The solder is solder paste, silver paste, indium or tin alloy. In this embodiment, the solder is solder paste.

In some embodiments, the first pad 50 and the first auxiliary pad 60 are formed by etching simultaneously.

S220, etching the substrate 20 to form a second pad 70 and a second auxiliary pad 80 spaced apart from the second pad 70 on the substrate 20; in some embodiments, the second pad 70 and the second auxiliary pad 80 are formed by etching at the same time.

In some embodiments, the order of step S210 and step S220 can be swapped.

S230, coating solder on the second solder pad 70 and the second auxiliary solder pad 80.

Among them, the thickness of the solder can be set according to actual needs.

In some embodiments, the method further includes coating solder on the first pad 50 and the first auxiliary pad 60.

S240, the die 10 is covered on the substrate 20, and the first pad 50 is aligned with the second pad 70 and attached to the solder on the second pad 70, and the first auxiliary pad 60 is aligned with the second auxiliary pad 80 and attached to the solder on the second auxiliary pad 80.

S250, heating the solder to melt the solder between the first pad 50 and the second pad 70, and melt the solder between the first auxiliary pad 60 and the second auxiliary pad 80. The melted solder can act on the first pad 50 and the first auxiliary pad 60 to drive the die 10 to rotate relative to the substrate 20 until the first pad 50 is aligned with the second pad 70.

When the first pad 50 is aligned with the second pad 70, the first auxiliary pad 60 is also aligned with the second auxiliary pad 80.

Among them, the solder between the first pad 50 and the second pad 70 will cool after melting, and form a first welding part 30 connecting the first pad 50 and the second pad 70; the solder between the first auxiliary pad 60 and the second auxiliary pad 80 will cool after melting, and form a second welding part 40 connecting the first auxiliary pad 60 and the second auxiliary pad 80. The first welding part 30 and the second welding part 40 are made of the same material.

The preparation method of the package structure 100 is as follows: first, a first pad 50 and a first auxiliary pad 60 spaced apart from the first pad 50 are formed on the die 10 by etching the die 10; then, a second pad 70 and a second auxiliary pad 80 spaced apart from the second pad 70 are formed on the substrate 20 by etching the substrate 20; then, solder is coated on the second pad 70 and the second auxiliary pad 80; then, the die 10 is covered on the substrate 20, and the first pad 50 is aligned with the second pad 70 and attached. The solder on the second pad 70 and the solder that makes the first auxiliary pad 60 aligned with the second auxiliary pad 80 and attached to the second auxiliary pad 80; finally, the solder is heated to melt the solder between the first pad 50 and the second pad 70, and melt the solder between the first auxiliary pad 60 and the second auxiliary pad 80. The molten solder can act on the first pad 50 and the first auxiliary pad 60 to drive the die 10 to rotate relative to the substrate 20 until the first pad 50 is aligned with the second pad 70. Since the first auxiliary pad 60 is located at the first preset position 11 on the die 10, and compared with other positions on the die 10 except the first preset position 11, the distance between the first preset position 11 and the center of gravity of the die 10 is the longest, the first auxiliary pad 60 located at the first preset position 11 can provide the maximum rotational torque for the die 10 to rotate relative to the substrate 20, thereby improving the self-alignment ability between the die 10 and the substrate 20, and further improving the packaging accuracy of the die 10 and the substrate 20, and to a certain extent, it can also expand the packaging use scenarios of the die 10.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

10: Grain

11: First default position

12: Other locations

50: First pad

60: First auxiliary pad

O ₁ : Center of gravity

Claims (11)

A packaging structure includes a die, a substrate and a first welding portion, wherein a first welding pad is provided on the die, a second welding pad corresponding to the first welding pad is provided on the substrate, and the first welding portion is connected between the first welding pad and the second welding pad. The improvement lies in that a first auxiliary welding pad spaced apart from the first welding pad is also provided on the die, a second auxiliary welding pad spaced apart from the second welding pad is also provided on the substrate, and the packaging structure further includes a second welding portion, the second auxiliary welding pad is provided corresponding to the first auxiliary welding pad, and the second welding portion is connected between the first auxiliary welding pad and the second auxiliary welding pad; the first auxiliary welding pad is provided at a first preset position on the die, and compared with other positions on the die except the first preset position, the distance between the first preset position and the center of gravity of the die is the longest. The packaging structure as described in claim 1, wherein the second auxiliary pad is disposed at a second preset position on the substrate, and the second preset position is disposed corresponding to the first preset position. The package structure as described in claim 1, wherein the first auxiliary pads are plural, and the plural first auxiliary pads are respectively arranged at the corners of the die. The package structure as described in claim 3, wherein the shape of the first auxiliary pad is rectangular, strip-shaped or circular, wherein the center of gravity of at least two of the first auxiliary pads located at two opposite corners in the diagonal direction of the die and the center of gravity of the first pad located in the central area of the die are both on a straight line. The package structure as described in claim 1, wherein the distance between the first auxiliary pad and the edge of the die is less than or equal to 3 mm. The package structure as described in claim 1, wherein the ratio of the area of the first auxiliary pad to the area of the first pad is in the range of 0.01-5. The package structure as described in claim 1, wherein the minimum spacing value between the first pad and the first auxiliary pad is A, there are plural first pads, the spacing value between any two of the plural first pads is B, and the ratio of A to B is in the range of 0.1-3. The package structure as described in claim 1, wherein the first auxiliary pad and the first pad have the same height relative to the surface of the die. The package structure as described in claim 1, wherein the first auxiliary pad and the second auxiliary pad have the same shape. A method for preparing a package structure, the improvement of which is that it includes the following steps: etching a crystal grain to form a first pad and a first auxiliary pad spaced apart from the first pad on the crystal grain, wherein the first auxiliary pad is formed at a first preset position on the crystal grain, and the distance between the first preset position and the center of gravity of the crystal grain is the longest compared with other positions on the crystal grain except the first preset position; etching a substrate to form a second pad and a second auxiliary pad spaced apart from the second pad on the substrate; coating the second pad and the second auxiliary pad with solder; and covering the crystal grain on a substrate; The substrate is provided, and the first pad is aligned with the second pad and attached to the solder on the second pad, and the first auxiliary pad is aligned with the second auxiliary pad and attached to the solder on the second auxiliary pad; the solder is heated to melt the solder between the first pad and the second pad, and the solder between the first auxiliary pad and the second auxiliary pad is melted, and the melted solder can act on the first pad and the first auxiliary pad to drive the grain to rotate relative to the substrate until the first pad is aligned with the second pad. The preparation method as described in claim 10, wherein the first pad and the first auxiliary pad are formed by etching at the same time, and the second pad and the second auxiliary pad are formed by etching at the same time.

Images