Welding wire bonding structure

Abstract

The utility model discloses a welding wire bonding structure, which comprises a chip, a concave bonding window is formed on the chip, and an exposed Pad is arranged in the bonding window; the gold cake is positioned in the bonding window and is combined on the Pad; and one end of the welding gold wire is welded with the gold cake. According to the welding wire bonding structure, the concave bonding window is formed on the passivation layer, the Pad is exposed in the bonding window, the gold cake is welded on the exposed Pad, and the welding chopper is directly welded with the gold cake, so that the welding chopper can be prevented from being in contact with the Pad and the passivation layer, the welding chopper is prevented from pressing against the Pad and the passivation layer, and the Pad and the passivation layer can be prevented from being damaged. The welding wire bonding structure provided by the utility model avoids the defect that the chip and the passivation layer are easy to damage and crack in the welding process, so that the product reliability and the product yield can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of welding wire bonding, in particular to a welding wire bonding structure. Background Art

[0002] In microwave multi-chip modules (MCMs), gold wire bonding is commonly used to interconnect components such as monolithic microwave integrated circuits, lumped resistors and capacitors with microstrip lines and coplanar waveguides, as well as between microwave transmission lines or with the RF ground plane.

[0003] Ultrasonic bonding is a solid-state metal bonding method. When ultrasonic energy and force are transmitted to the wire and pad, the metals undergo plastic deformation at the contact surface, ultimately forming a metallurgical bond. At the bonding interface between the wire and pad, friction between the metallization layers creates shear forces that act on the metal atoms at the interface, activating the contacting metal surfaces and removing contaminants from the bonding wire and pad interface, ultimately achieving a good bond.

[0004] The wedge bonder is larger than both the gold wire and the chip pad, and the wedge bond joints are relatively thin. If the chip pad and the wedge plane are not completely parallel or the chip passivation layer is too thick, the two sides of the wedge bonder will come into direct contact with the passivation layer during the bonding process, dissipating the ultrasonic energy and damaging the passivation layer. In severe cases, this can directly damage the passivation layer and the underlying circuitry and pad. Summary of the Invention

[0005] The purpose of the utility model is to provide a wire bonding structure, which forms a concave bonding window on the passivation layer, exposes the pad in the bonding window, welds a gold cake on the exposed pad, and directly welds the welding splitter to the gold cake, thereby avoiding contact between the welding splitter and the pad and the passivation layer, avoiding the welding splitter pressing the pad and the passivation layer, and thus avoiding damage to the pad and the passivation layer.

[0006] To this end, the present invention provides a wire bonding structure, comprising: a chip, a concave bonding window formed on the chip, an exposed pad in the bonding window; a gold cake, the gold cake being located in the bonding window and combined with the pad; and a welding gold wire, one end of the welding gold wire being welded to the gold cake.

[0007] Preferably, the top surface of the gold cake extends out of the bonding window, and the thickness of the gold cake is 10-15 μm.

[0008] Preferably, the diameter of the gold cake is 50-60 μm.

[0009] Preferably, the projection of the gold cake is a rectangle, and the side length of the gold cake is 50-60 μm.

[0010] Preferably, the projection of the bonding window is a rectangle, and the side length of the bonding window is 5-10 μm longer than the side length of the gold cake.

[0011] Preferably, the distance between one end of the welding gold wire and the center of the top surface of the gold cake is less than or equal to 10 μm.

[0012] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the present invention provides a wire bonding structure, which includes: a chip, a concave bonding window formed on the chip, an exposed pad in the bonding window; a gold cake, the gold cake being located in the bonding window and bonded to the pad; and a welding gold wire, one end of the welding gold wire being welded to the gold cake. The wire bonding structure of the present invention forms a concave bonding window on the passivation layer, exposes the pad in the bonding window, welds the gold cake on the exposed pad, and directly welds the welding blade to the gold cake, thereby avoiding contact between the welding blade and the pad and the passivation layer, and avoiding the welding blade pressing against the pad and the passivation layer, thereby avoiding damage to the pad and the passivation layer. The wire bonding structure of the present invention avoids the defect that the welding process easily causes damage to the chip and the passivation layer and cracks, thereby improving product reliability and product yield.

[0013] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of an embodiment of the wire bonding structure of the utility model;

[0015] Figure 2 It is a structural diagram of an embodiment of the chip of the utility model. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 、 Figure 2 As shown, the wire bonding structure of the present invention includes a chip 10, which includes a pad 11 and a passivation layer 12. The passivation layer 12 covers the pad 11. A concave bonding window 13 is formed on the passivation layer 12. The bonding window 13 extends only to the pad 11 so that the pad 11 is exposed within the bonding window 13.

[0018] In the present application, the bonding window 13 is formed on the passivation layer 12 in a manner commonly used in the art and is not specifically limited thereto.

[0019] The wire bonding structure of the present invention further includes a gold cake 20 . The gold cake 20 is located in the bonding window 13 and combined with the Pad 11 .

[0020] The thickness of the gold cake 20 is 10-15 μm, and the top surface of the gold cake 20 extends out of the bonding window 13, that is, the top surface of the gold cake 20 is higher than the top surface of the passivation layer 12; during welding, the welding blade 31 is in direct contact with the top surface of the gold cake 20 for welding, and the welding blade does not contact the passivation layer 12, which can prevent the welding blade from pressing against the passivation layer 12, thereby preventing the passivation layer 12 from being damaged.

[0021] The diameter of the gold cake 20 is 50-60 μm, which can increase the welding area, ensure that there is a sufficient welding contact area between the gold cake 20 and the Pad 11, and ensure the firmness and reliability of the welding between the gold cake 20 and the Pad 11.

[0022] The wire bonding structure of the present invention also includes a gold wire 30, one end of which is welded to the gold ingot 20, and the other end of which is welded to another welding point. During welding, the welding point of the welding blade 31 directly contacts the center of the top plane of the gold ingot 20, and the welding blade 31 does not contact the pad 11, thereby preventing the welding blade from pressing against the pad 11 and thus preventing damage to the pad 11.

[0023] The error between one end of the welding gold wire 30 and the center of the top surface of the gold cake 20 is less than or equal to 10μm, so that the gold cake 20 can be effectively welded to form an effective arch wire arc, and it can be ensured that the welding blade 31 will not contact the passivation layer 12 and will not cause damage to the passivation layer 12.

[0024] In one embodiment of the present application, the projection of the bonding window 13 can be circular, and the diameter of the bonding window 13 is 5-10 μm larger than the diameter of the gold cake 20, which can provide sufficient welding space for the gold cake 20, ensuring that the gold cake 20 can be effectively welded in the bonding window 13, and ensuring that the gold cake 20 can be effectively welded to Pad11.

[0025] In addition, the diameter of the bonding window 13 is 5-10 μm larger than the diameter of the gold cake 20, which can also form a gap between the gold cake 20 and the bonding window 13, thereby preventing the welding blade 31 from contacting the passivation layer 12 during welding, and preventing the welding blade 31 from pressing against the passivation layer 12, thereby preventing the passivation layer 12 from being damaged.

[0026] In other preferred embodiments, the projection of the gold cake 20 is a rectangle, and the side length of the gold cake 20 is 50-60 μm. The projection of the bonding window 13 is a rectangle, and the side length of the bonding window 13 is 5-10 μm longer than the side length of the gold cake 20. Sufficient welding space can be given to the gold cake 20 to ensure that the gold cake 20 can be effectively welded in the bonding window 13 and to ensure that the gold cake 20 can be effectively welded to the Pad 11. In addition, the side length of the bonding window 13 is 5-10 μm longer than the side length of the gold cake 20, and a gap can be formed between the gold cake 20 and the bonding window 13 to prevent the welding blade 31 from contacting the passivation layer 12 during welding, and to prevent the welding blade 31 from pressing against the passivation layer 12, thereby preventing the passivation layer 12 from being damaged.

[0027] The wire bonding structure of the present invention forms a concave bonding window 13 on the passivation layer 12, exposes the pad 11 within the bonding window 13, welds the gold wafer 20 to the exposed pad 11, and directly welds the welding blade 31 to the gold wafer 20. This prevents the welding blade 31 from contacting the pad 11 and the passivation layer 12, and prevents the welding blade 31 from pressing against the pad 11 and the passivation layer 12, thereby preventing damage to the pad 11 and the passivation layer 12. The wire bonding structure of the present invention avoids the defect that the welding process can easily cause damage to the chip 10 and the passivation layer 12 and cracks, thereby improving product reliability and product yield.

[0028] The wire bonding process of the wire bonding structure of the utility model comprises the following steps:

[0029] (1) A bonding window 13 is formed on the passivation layer 12 of the chip 10 , with the Pad 11 exposed in the bonding window 13 , and the chip 10 is cleaned.

[0030] In the present application, the bonding window 13 is formed on the passivation layer 12 in a manner commonly used in the art and is not specifically limited thereto.

[0031] In the present application, the projection of the bonding window 13 may be circular; in other preferred embodiments, the bonding window 13 may also be rectangular, elliptical, or other shapes, which are not specifically limited here.

[0032] In the present application, a plasma cleaning device can be used to perform plasma cleaning on the chip 10 to remove dust particles attached to the chip 10, especially to remove dust particles attached to the bonding window 13, thereby ensuring that the welding process is carried out smoothly and effectively.

[0033] (2) Use a ball bonding machine to bond the gold ball to Pad 11 of chip 10 . The gold ball is bonded in the center of Pad 11 , and the gold ball is bonded into a gold wafer 20 .

[0034] Specifically, a gold ball is placed in bonding window 13, contacting the pad 11 exposed inside and outside bonding window 13. A ball bonder is used to bond the gold ball to pad 11, extruding and bonding the gold ball to form a gold cake 20. The bottom surface of gold cake 20 is bonded to pad 11, and the top surface of gold cake 20 is exposed from bonding window 13 and is higher than the top surface of passivation layer 12.

[0035] The temperature of the ball bonder is 160-190℃. Within this temperature range, the activation degree of the combination between the aluminum pad and the gold ball can be improved, which can ensure that the gold ball can be well melted and extruded into a gold cake shape.

[0036] The thickness of the gold cake 20 is 10-15 μm, and the top surface of the gold cake 20 extends out of the bonding window 13, that is, the top surface of the gold cake 20 is higher than the top surface of the passivation layer 12; during welding, the welding blade 31 is in direct contact with the top surface of the gold cake 20 for welding, and the welding blade does not contact the passivation layer 12, which can prevent the welding blade 31 from pressing against the passivation layer 12, thereby preventing the passivation layer 12 from being damaged.

[0037] The diameter of the gold cake 20 is 50-60 μm, which can increase the welding area, ensure that there is a sufficient welding contact area between the gold cake 20 and the Pad 11, and ensure the firmness and reliability of the welding between the gold cake 20 and the Pad 11.

[0038] The error between the center of the welding point of the wedge welding blade 31 and the center of the top surface of the gold cake 20 is less than or equal to 10μm, so that the gold cake 20 can be effectively welded to form an effective arch wire arc, and it can be ensured that the welding blade 31 will not contact the passivation layer 12 and will not cause damage to the passivation layer 12.

[0039] (3) Use a wedge welding machine to weld the gold cake 20. Align the welding point of the wedge welding cutter 31 with the neck of the gold cake 20, pull the wire upward to form an arc, and then contact other welding points 40 for welding.

[0040] The temperature of the wedge bonding machine is 100-130° C. Within this temperature range, it can be ensured that the gold ball does not melt into liquid, and the gold cake 20 can be effectively welded to form an effective arch wire arc.

[0041] The wire bonding process of the present invention forms a concave bonding window 13 on the passivation layer 12, exposes the pad 11 within the bonding window 13, welds the gold cake 20 to the exposed pad 11, and directly welds the welding blade 31 to the gold cake 20. This can prevent the welding blade 31 from contacting the pad 11 and the passivation layer 12, and prevents the welding blade 31 from pressing against the pad 11 and the passivation layer 12, thereby preventing damage to the pad 11 and the passivation layer 12. The wire bonding process of the present invention can avoid the defects that easily lead to damage and cracks in the chip 10 and the passivation layer 12 during the welding process, thereby improving product reliability and product yield.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the above embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A wire bonding structure, characterized in that: include: A chip having a concave bonding window formed thereon, wherein the bonding window has an exposed pad; a gold cake, the gold cake being located in the bonding window and bonded to the pad; A gold wire is welded, wherein one end of the gold wire is welded to the gold cake.

2. The wire bonding structure according to claim 1, wherein: The distance between one end of the welding gold wire and the center of the top surface of the gold cake is less than or equal to 10 μm.

3. The wire bonding structure according to claim 1, wherein: The top surface of the gold cake extends out of the bonding window, and the thickness of the gold cake is 10-15 μm.

4. The wire bonding structure according to claim 1, wherein: The projection of the gold cake is circular, and the diameter of the gold cake is 50-60 μm.

5. The wire bonding structure according to claim 4, wherein: The projection of the bonding window is circular, and the diameter of the bonding window is 5-10 μm larger than the diameter of the gold cake.

6. The wire bonding structure according to claim 1, wherein: The projection of the gold cake is a rectangle, and the side length of the gold cake is 50-60 μm.

7. The wire bonding structure according to claim 6, wherein: The projection of the bonding window is a rectangle, and the side length of the bonding window is 5-10 μm longer than the side length of the gold cake.

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