A method for opening a stacked packaged chip

Abstract

A method for opening a stacked packaged chip is disclosed. The stacked packaged chip includes a lead frame, a plurality of dies stacked on the lead frame, and a packaging material covering the lead frame and the plurality of dies. The plurality of dies are stacked in a stepped shape, and a stepped surface connected to a metal wire is formed at the edge of the plurality of dies. The method for opening the package includes: obtaining an inclination angle according to the positions of the plurality of dies; adjusting the relative angle between the grinding direction and the stacked packaged chip according to the inclination angle, removing at least part of the packaging material, and cutting the metal wire. The method for opening a stacked packaged chip provided by the present invention calculates an inclination angle according to the positions of the plurality of dies; and places the stacked packaged chip obliquely relative to the horizontal plane according to the inclination angle, so that the blocked metal wire can be successfully opened.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a method for opening a stacked package chip. Background Art

[0002] A stacked package chip is wrapped with a relatively thick package on its surface, which serves the purposes of protection, support, heat dissipation, providing electrical connection, and reducing the volume of the package product. In the failure analysis of the chip, it is necessary to open the package.

[0003] Currently, the opening methods can be divided into chemical opening and mechanical opening: Chemical opening uses chemical corrosion to remove the packaging material, and its corrosiveness to the substrate and components has a certain degree of uncontrollability, and it cannot ensure the complete separation of the components and the substrate; Mechanical opening uses grinding methods, such as grinding (Polish) / automatic grinding (Autopolish) for overall and local opening, etc.; Mechanical local opening can selectively separate components.

[0004] However, with the increasing requirements of electronic products for miniaturization, functional integration, and large storage space, the miniaturization and high-density packaging forms of chips are also becoming more and more mainstream. However, while the increasingly complex package chips improve the logic operation function and storage space, they also pose new challenges to the opening and failure analysis of package chips: The existing technology can only grind and break the metal wire connections outside the die through mechanical opening, and cannot separate the metal wire connections of complex stacked structures blocked by dies directly above. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method for opening a stacked package chip to achieve the opening of the metal wires of the blocked die.

[0006] A method for opening a stacked package chip, the stacked package chip includes a lead frame, a plurality of dies stacked on the lead frame, and a packaging material covering the lead frame and the plurality of dies, the plurality of dies are stacked in a stepped shape, and a stepped surface connected to a metal wire is formed at the edge of the plurality of dies.

[0007] The opening method includes:

[0008] Obtain an inclination angle according to the positions of the plurality of dies;

[0009] Adjust the relative angle between the grinding direction and the stacked package chip according to the inclination angle, and remove at least part of the packaging material and cut off the metal wire.

[0010] Preferably, the inclination angle is obtained by measurement.

[0011] Preferably, the inclination angle is obtained by calculation.

[0012] Preferably, the spacing between adjacent dies of the stacked packaged chips is the same, and the widths of the stepped surfaces are the same.

[0013] Preferably, the inclination angle is calculated from the spacing between adjacent dies and the width of the stepped surface.

[0014] Preferably, the calculation method of the inclination angle is as follows:

[0015]

[0016] where α is the inclination angle, h is the spacing between adjacent dies, and l is the width of the stepped surface.

[0017] Preferably, in the step of removing at least part of the encapsulant and cutting the metal wires, the stacked packaged chips are placed obliquely with respect to the horizontal plane according to the inclination angle.

[0018] Preferably, by controlling the height difference between the two sides of the lead frame, the stacked packaged chips are placed obliquely with respect to the horizontal plane.

[0019] Preferably, the height difference H between the two sides of the lead frame is:

[0020] H = A * Sinα

[0021] where α is the inclination angle and A is the width of the lead frame.

[0022] Preferably, multiple dies are stacked together at the same inclination angle.

[0023] Preferably, multiple dies are stacked together at different inclination angles.

[0024] The method for opening the package of the stacked packaged chips provided by the present invention calculates the inclination angle according to the positions of the multiple dies; and places the stacked packaged dies obliquely with respect to the horizontal plane according to the inclination angle; so that the blocked metal wires can be successfully opened. Description of the Drawings

[0025] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0026] Figure 1 shows a schematic structural diagram of a stacked packaged chip according to a first embodiment of the present invention;

[0027] Figure 2 shows the process of opening the package of a traditional stacked packaged chip;

[0028] Figure 3Shows a flowchart of the method for opening a stacked package chip according to the first embodiment of the present invention;

[0029] Figure 4 Shows a schematic diagram of the first tilt angle of the stacked package chip according to the first embodiment of the present invention;

[0030] Figure 5 Shows a schematic structural diagram of the stacked package chip tilted relative to the horizontal plane at the first tilt angle;

[0031] Figure 6 Shows a schematic structural diagram of the stacked package chip tilted relative to the horizontal plane at the second tilt angle;

[0032] Figure 7 Shows a scanned image of a stacked package chip;

[0033] Figure 8 Shows a schematic diagram of opening a stacked package chip according to the second embodiment of the present invention. Detailed implementation manners

[0034] The present invention will be described in more detail below with reference to the accompanying drawings. In the respective drawings, the same elements are denoted by like reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0035] It should be understood that when describing the structure of a device, when a layer or a region is referred to as being "above" or "over" another layer or another region, it may mean directly above the other layer or another region, or there may be other layers or regions between it and the other layer or another region. And if the device is flipped, this layer or region will be "below" or "beneath" the other layer or region.

[0036] If it is for describing the case of being directly above another layer or another region, the expressions "directly on... above" or "above and adjacent to..." will be used herein.

[0037] The following further describes in detail the specific implementation manners of the present invention in conjunction with the drawings and embodiments.

[0038] Figure 1 Shows a schematic structural diagram of the stacked package chip according to the first embodiment of the present invention, as Figure 1 shown, the stacked package chip 100 includes a lead frame 110, a plurality of die 120 stacked on the lead frame 110, and a package material 130 covering the lead frame 110 and the plurality of die 120. Among them, the plurality of die 120 are stacked in a stepped shape, and a stepped surface 150 is formed at their edges, and metal wires 140 are connected between the stepped surfaces 150 of adjacent die and between the stepped surface 150 of the bottom die and the lead frame 110.

[0039] During the opening process, a part of the encapsulant 130 needs to be damaged to cut off the metal wire 140. Usually, a grinding tool is used to grind off the metal wire 130.

[0040] Figure 2 The opening process of a traditional stacked packaged chip is shown, as Figure 2 shown. The multiple die 120 are die 1201, die 1202, die 1203, die 1204, die 1205, die 1206, die 1207, and die 1208 respectively. In the traditional opening method, the stacked packaged chip 100 is placed horizontally, and the grinding tool 160 grinds the metal wire 140 on the encapsulant 130 and each step surface 150 of the multiple die 120 along a direction perpendicular to the horizontal plane. During the grinding process, the height of the grinding tool 160 and its relative position with respect to the metal wire 140 need to be adjusted multiple times to grind the metal wire 140 connected to each step surface 150. Among them, the metal wires connected to the step surfaces of die 1201, die 1202, die 1203, and die 1204 can be smoothly cut off. However, due to the shielding of die 1201, die 1202, die 1203, and die 1204, the metal wires connected to the step surfaces of die 1205 and die 1206 cannot be cut.

[0041] Figure 3 The flowchart of the opening method of the stacked packaged chip according to the first embodiment of the present invention is shown, as Figure 3 shown. The opening method of the stacked packaged chip in this embodiment includes the following steps.

[0042] S10: Obtain the tilt angle according to the positions of the multiple die of the stacked packaged chip.

[0043] The tilt angle of the stacked packaged chip can be obtained by calculation, measurement, or specific parameters marked on the product. In this step, the tilt angle of the stacked packaged chip is obtained by calculation, and the calculation process of the tilt angle will be described in detail below.

[0044] Figure 4 The schematic diagram of the process of obtaining the tilt angle of the stacked packaged chip according to the first embodiment of the present invention is shown; as Figure 4 shown, die 1201, die 1202, die 1203, and die 1204 are stacked together at a first tilt angle, and their edges form step surfaces; die 1205, die 1206, die 1207, and die 1208 are stacked together at a second tilt angle, and their edges form step surfaces. Among them, the tilt directions of the first tilt angle and the second tilt angle are different.

[0045] Among them, the first inclination angle ɑ is calculated from the pitch h between adjacent die chips and the step width l.

[0046] The pitch between adjacent die chips of the stacked package chip 100 is the same, all being h. Herein, the pitch between adjacent die chips is the distance from the top surface of the lower die chip to the top surface of the adjacent upper die chip, for example, the pitch between the top surface of die chip 1201 and the top surface of die chip 1202. Further, the step widths of the step surfaces 150 are the same, all being l. In this embodiment, the step width of each level is the distance from the edge of the lower die chip to the edge of the adjacent upper die chip, for example, the pitch between the edge of die chip 1201 and the edge of die chip 1202. The first inclination angle is calculated from the pitch h between adjacent die chips and the step width l of the step surface as follows:

[0047]

[0048] where ɑ is the first inclination angle, h is the pitch between adjacent die chips of the stacked package chip 100, and l is the step width of the step surface 150.

[0049] Similarly, the second inclination angle θ is calculated in the same way.

[0050] S20: Adjust the relative angle between the grinding direction and the stacked package chip according to the inclination angle, and remove at least part of the encapsulant and cut off the metal wires.

[0051] In this step, the stacked package chip 100 is placed obliquely relative to the horizontal plane according to the inclination angle. In this embodiment, the placement angle of the stacked package chip is adjusted to adapt to the grinding direction of the grinding tool. In other embodiments, the grinding angle of the grinding tool can also be adjusted to adapt to different inclination angles of the stacked package chip.

[0052] In this embodiment, multiple die chips 120 are stacked together in different inclination directions, and it is necessary to adjust the placement position of the stacked package chip 100 and grind the metal wires 140 in different inclined states.

[0053] Figure 5 The structural schematic diagram showing the stacked package chip placed obliquely relative to the horizontal plane at the first inclination angle is as Figure 5 shown. In this embodiment, by controlling the height difference between the two sides of the lead frame 110, the stacked package chip 100 is placed obliquely relative to the horizontal plane at the first inclination angle. When the stacked package chip 100 is placed obliquely at the first inclination angle, the lead frame 110 is also placed obliquely at the first direction inclination angle, and the height difference between the first side and the second side of the lead frame 110 is H 1 , where the second side is higher than the first side.

[0054] Specifically, in this embodiment, the width of the lead frame 110 is A, and the first height difference between the two sides of the lead frame 110 is H 1 is:

[0055] H 1 = A * Sinα

[0056] As Figure 5 shown, the height difference between the first side and the second side of the lead frame 110 is H 1 , and when the second side is higher than the first side, the stacked package chip 100 is placed inclined with respect to the horizontal plane at a first inclination angle. In this state, the grinding tool 160 grinds along a direction perpendicular to the horizontal plane, and only by moving the grinding tool 160 in the horizontal direction can the grinding of the die 1201, die 1202, die 1203, and die 1204 be achieved.

[0057] Figure 6 The structural schematic diagram showing the stacked package chip placed inclined with respect to the horizontal plane at a second inclination angle is as Figure 6 shown. The inclination direction of the second inclination angle is different from that of the first inclination angle. When the stacked package chip 100 is placed inclined at the second inclination angle, the height difference between the first side and the second side of the lead frame 100 is H 2 , where the first side is higher than the second side.

[0058] Wherein, the second height difference between the two sides of the lead frame 110 is H 2 is:

[0059] H 2 = A * Sinθ

[0060] As Figure 6 shown, the height difference between the first side and the second side of the lead frame 110 is H 2 , and when the first side is higher than the second side, the stacked package chip 100 is placed inclined with respect to the horizontal plane at a second inclination angle. In this state, the shielding of the upper dies 1201, 1202, 1203, and 1204 is removed, the grinding tool 160 grinds along a direction perpendicular to the horizontal plane, and only by moving the grinding tool 160 in the horizontal direction can the grinding of the dies 1205, 1206, 1207, and 1208 be achieved.

[0061] In this embodiment, multiple die 120 are stacked together at different tilt angles in different directions, and it is necessary to calculate the tilt angle ɑ in the first direction and the tilt angle θ in the second direction respectively. In other embodiments, multiple die 120 are stacked together at the same tilt angle in the same direction, and only one tilt angle in the same direction needs to be calculated.

[0062] In a more complex embodiment, the die of the stacked package chip are also stacked together in more than two different tilt directions.

[0063] In this embodiment, the size parameters of the stacked package chip are obtained by an acoustic scanning microscope SAM and X-ray. Of course, it can also be achieved by any other means capable of obtaining the size parameters of the stacked package chip. This embodiment is only for illustration.

[0064] The size parameters of the stacked package chip include, for example, the spacing h between adjacent die, the step width l, and the width A of the lead frame 110 and other parameters.

[0065] Figure 7 (a) and Figure 7 (b) respectively show the front scan image and the back scan image of a stacked package chip obtained by an acoustic scanning microscope SAM and X-ray. As Figure 7 (a) and Figure 7 (b) show, the image of the stacked package chip obtained by an acoustic scanning microscope SAM can clearly observe its specific structure. Supplementary with X-ray, the specific sizes of each component in the stacked package chip can be obtained.

[0066] Figure 8 Shows the opening diagram of the stacked package chip according to the second embodiment of the present invention. As Figure 8 shown, the stacked package chip 200 is more complex, which includes a lead frame 210, multiple die 220 stacked on the lead frame 210, and a packaging material 230 covering the lead frame 210 and the multiple die 220. Among them, the multiple die 120 are stacked in a stepped shape in more than two different tilt directions, forming a step surface 250 at the edge, and a metal wire 240 is connected to the step surface 250.

[0067] In this embodiment, the shielding phenomenon of the die 220 is more serious. Using the method described in the first embodiment to open it, the stacked package chip 200 is placed obliquely in multiple times to achieve the cutting of the complex metal wire 240. Figure 7 Shows a schematic diagram of the relative tilt of the grinding tool 260. Actually, the stacked package chip 200 can be tilted.

[0068] As described above with reference to the embodiments of the present invention, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the above description. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and its modifications based on the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for opening a stacked packaged chip, characterized in that, the stacked packaged chip includes a lead frame, a plurality of dies stacked on the lead frame, and a packaging material covering the lead frame and the plurality of dies. The plurality of dies are stacked in a stepped shape, and a stepped surface connected to a metal wire is formed at the edge of the plurality of dies. The method for opening the package includes: According to the positions of the plurality of dies, obtaining an inclination angle from the spacing between adjacent dies and the width of the stepped surface; According to the inclination angle, adjusting the relative angle between the grinding direction and the stacked packaged chip to remove at least part of the packaging material and cut off the metal wire; Wherein, the spacing between adjacent dies forms one right-angled side of a triangle, the width of the stepped surface forms the other right-angled side of the triangle, and the inclination angle is the included angle between the right-angled side formed by the width of the stepped surface and the hypotenuse of the triangle.

2. The method for opening a stacked packaged chip according to claim 1, characterized in that, the inclination angle is obtained by measurement.

3. The method for opening a stacked packaged chip according to claim 1, characterized in that, the inclination angle is obtained by calculation.

4. The method for opening a stacked packaged chip according to claim 3, characterized in that, the spacing between adjacent dies of the stacked packaged chip is the same, and the width of the stepped surface is the same.

5. The method for opening a stacked packaged chip according to claim 4, characterized in that, the inclination angle is calculated from the spacing between adjacent dies and the width of the stepped surface.

6. The method for opening a stacked packaged chip according to claim 5, characterized in that, the calculation method of the inclination angle is: ， Wherein, is the tilt angle, h is the pitch between adjacent die, l is the width of the said stepped surface.

7. The method for opening a stacked packaged chip according to claim 1, characterized in that, placing the stacked packaged chip inclined relative to the horizontal plane according to the inclination angle.

8. The method for opening a stacked packaged chip according to claim 7, characterized in that, by controlling the height difference between both sides of the lead frame, the stacked packaged chip is placed inclined relative to the horizontal plane.

9. The method for opening a stacked packaged chip according to claim 8, characterized in that, the height difference H between both sides of the lead frame is: H = A * Sinα Among them, is the tilt angle, and A is the width of the lead frame.

10. The method for opening a stacked packaged chip according to claim 1, characterized in that, a plurality of dies are stacked together with the same inclination angle.

11. The method for opening a stacked packaged chip according to claim 1, characterized in that, a plurality of dies are stacked together with different inclination angles.

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