Long wire arc across die connection method

Abstract

The application relates to the chip technical field and particularly relates to a long-line-arc cross-die connecting method and structure. The method comprises the following steps: S1, mounting a first chip on a lead frame; S2, mounting a second chip on one side surface of the first chip; S3, mounting a dummy chip on the other side surface of the first chip; and S4, bonding the second chip and the pins on the two sides of the lead frame through line arcs. In the step S4, when the second chip is bonded with the pins far away through the line arcs, one side of the line arcs falls on the dummy chip. Compared with the prior art, the PCB adapter plate design is cancelled and is completed through the dummy chip. The dummy chip is cut from a wafer filling chip (namely wafer dummy), has no internal circuit, does not contain conductive material and is non-conductive. When the long-line-arc cross-die is realized, the line arcs contact the dummy chip, so that the quality problem of short circuit does not occur.

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] The die stacking technology is widely used in chip design and production, which has led to the process requirements of long arc across the die. In the actual production process, Figures 7-8 As shown, when the proportion of long wire arcs crossing dies exceeds 75%, the wire arcs are too long and short-circuit with the lead frame. Or when stacking dies, the wire arcs are too long and short-circuit with the stacked dies, causing short quality problems.

[0003] The current technical solution is to add a PCB adapter board 10, such as Figures 9-10 As shown, the internal circuits of the adapter board 10 are connected, and the solder joints at both ends of the circuit are respectively soldered to the chip and the lead frame using gold wires. This can solve the short circuit problem of long arcs across the die, but it increases the cost of the PCB adapter board and the soldering wires. The increase in soldering wires reduces the operating efficiency of the WB equipment, resulting in a significant increase in production costs. 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 objectives, a long arc span Die connection method is designed, which includes the following steps:

[0006] S1, placing the first chip onto the lead frame;

[0007] S2, placing the second chip on one side surface of the first chip;

[0008] S3, placing a dummy chip on the other side surface of the first chip;

[0009] S4, bonding the second chip to the first chip and the pins on both sides of the lead frame through wire arcs;

[0010] In step S4, when the second chip is bonded to the pins that are farther away through the wire arc, one side of the wire arc falls on the dummy chip.

[0011] A breaking point is provided on the line arc at the edge of the false piece.

[0012] The folding angle of the folding point is 40-60°. In this embodiment, the folding angle is 45°.

[0013] In the step S3, the dummy chip is bonded and fixed to the first chip via the DAF film.

[0014] The false chip is not provided with an internal circuit and does not conduct electricity.

[0015] In the step S1 to the step S3, the sheet feeding machine is used for sheet feeding.

[0016] In the step S4, the wire bonding is completed by the WB machine once.

[0017] To achieve the above object, a long wire arc across die connecting structure is designed, which comprises a lead frame, one side of the lead frame is provided with a first chip, one side of the first chip is provided with a second chip, the other side of the first chip is provided with a false chip, the second chip is bonded with the first chip and the lead frame on both sides through a wire arc, and the second chip is bonded with the lead frame through a wire arc when the second chip is far away from the lead frame, and the wire arc falls on the false chip.

[0018] The wire arc on the edge of the false chip is provided with a folding point.

[0019] The folding angle of the folding point is 40-60°.

[0020] Compared with the prior art, the PCB adapter plate design is cancelled, and the false chip is completed, the false chip is cut from a wafer filling piece (i.e. wafer dummy), there is no internal circuit, no conductive material is contained, and it is not conductive, when the long wire arc crosses the die, the wire arc contacts the false chip, and the quality problem of short circuit does not occur. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present application.

[0022] Figure 2 It is a sectional view of Figure 1

[0023] Figure 3 It is a structural schematic diagram of the second chip wire arc in the first embodiment of the present application.

[0024] Figure 4 It is a structural schematic diagram of the false chip in the first embodiment of the present application.

[0025] Figure 5 It is a structural schematic diagram of the second chip wire arc in the second embodiment of the present application.

[0026] Figure 6 It is a structural schematic diagram of the false chip in the second embodiment of the present application.

[0027] Figure 7 It is a structural schematic diagram of the prior art before the present application is improved.

[0028] Figure 8 It is a sectional view of Figure 7

[0029] ​​Figure 9 Another prior art structure schematic diagram before the improvement of the present application.

[0030] Figure 10 For Figure 9 a cross-sectional view. DETAILED DESCRIPTION

[0031] The present application will be further described below with reference to the accompanying drawings. Example one

[0032] As Figures 1-2 shown, the long wire arc across Die connection method in this embodiment includes the following steps:

[0033] S1, the first chip 1 is mounted on the lead frame 4; S2, the second chip 2 is mounted on one side surface of the first chip 1; S3, the dummy chip 3 is mounted on the other side surface of the first chip 1; S4, the second chip 2 and the pins 5 on both sides of the lead frame 4 are bonded by the wire arc 6.

[0034] In step S4, when the second chip 2 and the pins 5 far apart are bonded by the wire arc 6, one side of the wire arc 6 falls on the dummy chip 3.

[0035] In step S3, the dummy chip 3 is adhered and fixed to the first chip 1 by the DAF film.

[0036] The dummy chip 3 is cut from a wafer dummy, also known as Dummy die, test wafer, silicon wafer, without internal circuit and without conducting.

[0037] In steps S1 to S3, the mounting machine is used for mounting.

[0038] In step S4, the WB machine completes the soldering in one time. By using the dummy chip to replace the existing PCB adapter board, the cost of one PCB adapter board is saved, and the soldering at both ends of the PCB adapter board is not used, which reduces the soldering operation time of the WB machine, and can greatly improve the operation efficiency of the WB.

[0039] The structure obtained by the above long wire arc across Die connection method is shown in Figures 1-2 , one side of the lead frame 4 is provided with the first chip 1, one side of the first chip 1 is provided with the second chip 2, the other side of the first chip 1 is provided with the dummy chip 3, and the second chip 2 is bonded to the pins 5 on both sides of the lead frame 4 through the wire arc 6, when the second chip 2 and the pins 5 far apart are bonded by the wire arc 6, one side of the wire arc 6 falls on the dummy chip 3.

[0040] In specific use, the first chip 1, the lead frame 4, the second chip 2 and the dummy chip 3 are connected by the DAF film 8.

[0041] In this embodiment, the long wire arc 6 surface is in slight contact with the surface of the dummy 3 to support the long wire arc from collapsing after wire bonding is completed. Since the dummy 3 does not contain conductive material, the contact between the die wire arc 6 and the surface of the dummy 3 will not conduct electricity to cause a short circuit quality problem. Using the long wire arc cross-die connection method in this embodiment, after wire bonding of the chip, it is confirmed that there is no abnormality of wire arc short circuit or open circuit. After encapsulation, it is confirmed that there is no abnormality of wire arc deviation, meeting the quality standard. Embodiment Two

[0042] This embodiment only illustrates the differences from Embodiment One, and the same parts will not be repeated.

[0043] The difference between this embodiment and Embodiment One is that, as shown in Figures 5-6 , a folding point 7 is arranged on the wire arc 6 at the edge position of the dummy 3. The folding angle of the folding point 7 is 40-60°. In this embodiment, the folding angle is 45°.

[0044] Now the process requires products to be smaller and thinner, and the cross-die product occupies more thickness space, leaving limited space for mold clearance (i.e. mold clearance). The minimum design is 50um. Therefore, the height requirement of the wire arc cannot be too high. After adding the dummy 3, the cross-die wire arc ratio is larger. In specific use, the wire arc 6 will interfere with the edge of the dummy 3 during wire bonding, as shown in Figures 3-4 , the WB machine uses the conventional wire bonding process, which will cause tight wire, resulting in ball neck breakage anomaly. Specifically, the wire bonding head 13 first bonds the wire at the first bonding point 11 of the second chip 2. The entire wire bonding head is vertically released upwards to the required height, and then the second bonding point 12 is bonded. At this time, the wire arc 6 interferes with the edge of the dummy 3, causing the wire arc 6 to be tight, resulting in an abnormality of the ball stem breakage at the first bonding point 11 of the second chip 2.

[0045] In this embodiment, the wire bonding process is adjusted. When the wire head is released, the edge position of the dummy 3 is used as the folding point position, and the folding angle is 45 degrees. During the wire bonding process, the upper right corner of the dummy 3 will not hit the wire arc, causing the tight wire problem.

Claims

1. A method for long wire arc across die connection, the method comprising: It comprises the following steps: ​ S1, the first chip (1) is mounted on the lead frame (4); S2, the second chip (2) is mounted on one side of the first chip (1); S3, the dummy chip (3) is mounted on the other side of the first chip (1); S4, the second chip (2) is bonded with the pins (5) on both sides of the first chip (1) and the lead frame (4) through the wire arc (6); In the step S4, when the second chip (2) is bonded with the pins (5) far away through the wire arc (6), one side of the wire arc (6) falls on the dummy chip (3).

2. The method of claim 1, wherein: The wire arc (6) at the edge position of the dummy chip (3) is provided with a folding point (7).

3. The method of claim 2, wherein: The folding angle of the folding point (7) is 40-60°.

4. The method of claim 3, wherein: The folding angle of the folding point (7) is 45°.

5. The method of claim 1, wherein: In the step S3, the dummy chip (3) is adhered and fixed with the first chip (1) through the DAF film (8).

6. The method of claim 1, wherein: The dummy chip (3) is not provided with an internal circuit and does not conduct electricity.

7. The method of claim 1, wherein: In the steps S1-S3, the mounting is performed by a mounting machine.

8. The method of claim 1, wherein: In the step S4, the wire bonding is completed by a WB machine once.

9. A long wire arc across die connection structure comprising a lead frame, characterized by: The lead frame (4) is provided with the first chip (1), one side of the first chip (1) is provided with the second chip (2), the other side of the first chip (1) is provided with the dummy chip (3), the second chip (2) is bonded with the pins (5) on both sides of the first chip (1) and the lead frame (4) through the wire arc (6), and when the second chip (2) is bonded with the pins (5) far away through the wire arc (6), one side of the wire arc (6) falls on the dummy chip (3).

10. The long wire arc across die connection structure of claim 9, wherein: The wire arc (6) at the edge position of the dummy chip (3) is provided with a folding point (7).

11. The long wire arc across die connection structure of claim 10, wherein: The folding angle of the folding point (7) is 40-60°.

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