Long-line arc cross-Die connection method

Abstract

The invention relates to the technical field of chips, in particular to a long-line arc cross-Die connection method and structure. Comprising the following steps: S1, loading a first chip onto a lead frame; s2, loading a second chip to the surface of one side of the first chip; s3, loading the dummy chip to the surface of the other side of the first chip; s4, bonding the second chip with the first chip and the pins on the two sides of the lead frame through wire arcs; in the step S4, when the second chip is bonded with the pin far away from the second chip through a wire arc, one side of the wire arc falls on the dummy chip. Compared with the prior art, the design of a PCB (Printed Circuit Board) adapter plate is canceled, the process is completed through a dummy chip, the dummy chip is formed by cutting a wafer filling chip (i.e., wafer dummy), no circuit exists in the dummy chip, no conductive material is contained in the dummy chip, the dummy chip is non-conductive, and when a long line arc crosses die, the line arc is in contact with the dummy chip, so that the quality problem of short circuit is avoided.

Description

Technical Field

[0001] The present invention relates to the field of chip technology, in particular to a long-line arc-spanning Die connection method and structure. Background Art

[0002] Die stacking technology is widely used in chip design and production, which leads to the process requirements of long arc across die. In the actual production process, Figures 7 and 8 As shown in the figure, when the ratio of long arcs across dies exceeds 75%, the arcs are too long to short-circuit with the lead frame, or when stacking dies, the arcs are too long to short-circuit with the stacked dies, resulting in short quality problems.

[0003] The current technical solution is to add a PCB adapter board 10, such as Figures 9 and 10 As shown, the internal circuit of the adapter board 10 is connected, and the solder joints at both ends of the circuit are respectively welded to the chip and the lead frame using gold wires, which can solve the short circuit problem of long arc across the die, but increases the cost of the PCB adapter board and the welding wires. The increase in welding wires reduces the operating efficiency of the WB equipment, thereby significantly increasing the production cost. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a long-line arc-span Die connection method and structure, thereby reducing the manufacturing cost of the current long-line arc-span Die process.

[0005] To achieve the above purpose, a long arc span Die connection method is designed, which includes the following steps: S1, placing a first chip on a lead frame; S2, placing a second chip on a side surface of the first chip; S3, placing a dummy chip on the other side surface of the first chip; S4, bonding the second chip to the first chip and the pins on both sides of the lead frame through wire arcs; In the step S4, when the second chip is bonded to the pins which are far away from each other through the wire arc, one side of the wire arc falls on the dummy chip.

[0006] The line arc at the edge of the fake piece is provided with an inflection point.

[0007] The folding angle of the folding point is 40-60°. In this embodiment, the folding angle is 45°.

[0008] In the step S3, the dummy chip is bonded and fixed to the first chip via the DAF film.

[0009] The dummy film has no circuit inside and does not conduct electricity.

[0010] In the steps S1 to S3, the film is loaded by a film loading machine.

[0011] In the step S4, the wire bonding is completed at one time by the WB machine.

[0012] To achieve the above purpose, a long wire arc cross-die connection structure is designed, including a lead frame, a first chip is provided on one side of the lead frame, a second chip is provided on one side of the first chip, and a dummy chip is provided on the other side of the first chip. The two sides of the second chip are bonded to the first chip and the pins on both sides of the lead frame through wire arcs respectively. When the second chip is bonded to the pins far away through the wire arc, one side of the wire arc falls on the dummy chip.

[0013] The line arc at the edge of the fake piece is provided with an inflection point.

[0014] The inflection point has an angle of 40-60°.

[0015] Compared with the prior art, the present invention eliminates the design of a PCB adapter plate and uses a dummy sheet. The dummy sheet is cut from a wafer filling sheet (i.e., a wafer dummy), has no circuit inside, contains no conductive material, and is non-conductive. When a long wire arc crosses the die, the wire arc contacts the dummy sheet, and a short circuit quality problem will not occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Figure 2 for Figure 1 Cross-sectional view of .

[0018] Figure 3 It is a schematic diagram of the structure of the second chip at the line arc in the first embodiment of the present invention.

[0019] Figure 4 It is a structural schematic diagram of the dummy film in the first embodiment of the present invention.

[0020] Figure 5 It is a schematic diagram of the structure of the second chip at the line arc in the second embodiment of the present invention.

[0021] Figure 6 It is a structural schematic diagram of the dummy film in the second embodiment of the present invention.

[0022] Figure 7 It is a structural schematic diagram of the prior art before the present invention improves.

[0023] Figure 8 for Figure 7 Cross-sectional view of .

[0024] Fig. 9 It is a structural schematic diagram of another prior art before the improvement of the present invention.

[0025] Fig.10 for Fig. 9 Cross-sectional view of . DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings. Embodiment 1

[0027] like Figure 1 to Figure 2 As shown, the long arc span Die connection method in this embodiment includes the following steps: S1, mount the first chip 1 on the lead frame 4; S2, mount the second chip 2 on one side of the first chip 1; S3, mount the dummy chip 3 on the other side of the first chip 1; S4, bond the second chip 2 to the first chip 1 and the pins 5 on both sides of the lead frame 4 through the wire arc 6; In step S4 , when the second chip 2 is bonded to the lead 5 which is far away from the second chip 2 via the wire arc 6 , one side of the wire arc 6 falls on the dummy chip 3 .

[0028] In step S3, the dummy chip 3 is bonded and fixed to the first chip 1 through the DAF film.

[0029] The dummy wafer 3 is cut from a wafer filling sheet (i.e., a wafer dummy), also called a dummy die, a test wafer, or a silicon chip. It has no circuit inside and does not conduct electricity.

[0030] In step S1 to step S3, the film is loaded by a film loading machine.

[0031] In step S4, the wire welding is completed at one time by the WB machine. By replacing the existing PCB adapter board with a dummy sheet, the cost of a PCB adapter board is saved, and the wire welding at both ends of the PCB adapter board is not used, which reduces the wire welding operation time of the WB machine and can greatly improve the operation efficiency of the WB.

[0032] The structure obtained by the above long arc span Die connection method is as follows Figure 1 to Figure 2 As shown, a first chip 1 is provided on one side of the lead frame 4, a second chip 2 is provided on one side of the first chip 1, and a dummy chip 3 is provided on the other side of the first chip 1. Both sides of the second chip 2 are bonded to the first chip 1 and the pins 5 on both sides of the lead frame 4 through wire arcs 6 respectively. When the second chip 2 is bonded to the pins 5 that are far away through the wire arcs 6, one side of the wire arcs 6 falls on the dummy chip 3.

[0033] During specific use, the first chip 1 is connected to the lead frame 4 , the second chip 2 , and the dummy chip 3 via the DAF film 8 .

[0034] In this embodiment, after the wire bonding is completed, the surface of the long wire arc 6 slightly contacts the surface of the dummy film 3 to support the long wire arc and prevent it from collapsing. Since the dummy film 3 does not contain conductive materials, the cross-die wire arc 6 will not conduct electricity when in contact with the surface of the dummy film 3, which will cause the quality problem of short circuit. Using the long wire arc cross-die connection method in this embodiment, after the lead bonding of the chip, it is confirmed that there is no abnormality of wire arc short circuit or open circuit. After plastic packaging, it is confirmed that there is no abnormality of wire arc deviation, which meets the quality standards. Embodiment 2

[0035] This embodiment only describes the differences from the first embodiment, and the similarities are not described again.

[0036] The difference between this embodiment and the first embodiment is that Figures 5 and 6 As shown, a folding point 7 is provided on the line arc 6 at the edge of the false sheet 3. The folding angle of the folding point 7 is 40-60°. In this embodiment, the folding angle is 45°.

[0037] The current process requires products to be smaller and thinner. Since stacked die products occupy more space, the space left for mold clearance is limited, and the minimum design is 50um. Therefore, the requirement for the arc height should not be too high. After adding the dummy sheet 3, the cross-die arc ratio is relatively large. In the specific use process, the arc 6 will interfere with the edge of the dummy sheet 3 during the welding process, such as Figure 3 to Figure 4 As shown, the conventional wire bonding process used by the WB machine will cause tight wire pulling, resulting in abnormal ball neck breaking. Specifically, the wire bonding head 13 first bonds the wire at the solder joint 11 of the second chip 2, and the entire wire bonding head releases the gold wire vertically upward. When the required height is reached, the wire bonding at the solder joint 2 12 is performed. At this time, the wire arc 6 interferes with the edge of the dummy chip 3, causing the wire arc 6 to be tightly pulled, resulting in abnormal ball neck breaking at the solder joint 11 of the second chip 2.

[0038] This embodiment adjusts the wire welding process. When the welding head is laying out the wire, the edge of the dummy piece 3 is used as the inflection point, with an angle of 45 degrees. During the wire welding process, the upper right corner of the dummy piece 3 will not hit the wire arc, causing the problem of tight wire pulling.

Claims

1. A long line arc span Die connection method, characterized by: The steps include: S1, mounting a first chip (1) on a lead frame (4); S2, placing the second chip (2) on a side surface of the first chip (1); S3, placing the dummy chip (3) on the other side surface of the first chip (1); S4, bonding the second chip (2) to the first chip (1) and the leads (5) on both sides of the lead frame (4) through wire arcs (6); In the step S4, when the second chip (2) is bonded to the lead (5) which is far away from the second chip (2) via the wire arc (6), one side of the wire arc (6) falls on the dummy chip (3).

2. A long line arc span Die connection method according to claim 1, characterized in that: A folding point (7) is provided on the line arc (6) at the edge of the false piece (3).

3. A long-line arc span Die connection method according to claim 2, characterized in that: The folding angle of the folding point (7) is 40-60°. In this embodiment, the folding angle is 45°.

4. A long-line arc span Die connection method according to claim 1, characterized in that: In the step S3, the dummy chip (3) is bonded and fixed to the first chip (1) via the DAF film (8).

5. A long-line arc span Die connection method according to claim 1, characterized in that: The dummy film (3) has no circuit inside and does not conduct electricity.

6. A long-line arc span Die connection method according to claim 1, characterized in that: In the steps S1 to S3, the film is loaded by a film loading machine.

7. A long-line arc span Die connection method according to claim 1, characterized in that: In the step S4, the wire bonding is completed at one time by the WB machine.

8. A long arc-crossing die connection structure, comprising a lead frame, characterized in that: A first chip (1) is provided on one side of the lead frame (4), a second chip (2) is provided on one side of the first chip (1), a dummy chip (3) is provided on the other side of the first chip (1), and both sides of the second chip (2) are bonded to the first chip (1) and the pins (5) on both sides of the lead frame (4) through wire arcs (6), respectively. When the second chip (2) is bonded to the pins (5) that are far away through the wire arcs (6), one side of the wire arc (6) falls on the dummy chip (3).

9. The long arc span Die connection structure according to claim 1, characterized in that: A folding point (7) is provided on the line arc (6) at the edge of the false piece (3).

10. The long arc span Die connection structure according to claim 1, characterized in that: The folding angle of the folding point (7) is 40-60°.

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