Welding wire bonding structure and welding wire bonding process

Abstract

The invention discloses a welding wire bonding structure and a welding wire bonding process, and the welding wire bonding structure comprises a chip which is provided with a recessed bonding window, and the interior of the bonding window is provided with an exposed Pad; 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 in the passivation layer, the Pad is exposed in the bonding window, the gold cake is welded to the exposed Pad, and the welding chopper is directly welded to the gold cake, so that the welding chopper can be prevented from making contact with the Pad and the passivation layer, the welding chopper is prevented from abutting against the Pad and the passivation layer, and therefore the Pad and the passivation layer can be prevented from being damaged. According to the welding wire bonding structure disclosed by the invention, the defect that the chip and the passivation layer are easy to damage and crack in the welding process is overcome, so that the product reliability and the product yield can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding wire bonding, and in particular to a welding wire bonding structure and a welding wire bonding process. Background Art

[0002] In microwave multi-chip modules (MCMs), gold wire bonding is usually used to achieve the interconnection between monolithic microwave integrated circuits, lumped resistors and capacitors and other components with microstrip lines, coplanar waveguides, as well as the interconnection 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 lead and the pad, the metal undergoes plastic deformation at the contact surface, eventually forming a metallurgical bond. At the bonding interface between the metal lead and the pad, friction occurs between the metallization layers, forming a shear force that acts on the metal atoms at the contact interface, thereby activating the contacting metal surface and removing contaminants from the bonding surface of the bonding lead and the pad, ultimately achieving a good bonding effect.

[0004] The wedge welding knife is larger than the gold wire and chip pad, and the thickness of the wedge welding point is relatively thin. When the chip pad is not completely parallel to the wedge plane or the chip passivation layer is too thick, the two sides of the wedge will directly contact the passivation layer during the welding process, dispersing the ultrasonic energy and destroying the passivation layer. In severe cases, the passivation layer and the circuit and pad underneath will be directly destroyed at the same time. Summary of the invention

[0005] The object of the present invention is to provide a wire bonding structure and a wire bonding process, by forming a concave bonding window on the passivation layer, exposing the Pad in the bonding window, welding a gold cake on the exposed Pad, and directly welding the welding splitter to the gold cake, which can avoid the welding splitter from contacting the Pad and the passivation layer, and avoid the welding splitter from pressing the Pad and the passivation layer, thereby avoiding the Pad and the passivation layer from being damaged.

[0006] To this end, the present invention provides a wire bonding structure, comprising: a chip, a concave bonding window formed on the chip, and an exposed Pad in the bonding window; a gold cake, the gold cake is located in the bonding window and combined on the Pad; and a welding gold wire, one end of the welding gold wire is 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] The present invention also provides a wire bonding process of the wire bonding structure, comprising the following steps: (1) Clean the chip; (2) Using a ball bonding machine to bond a gold ball to the pad of the chip, the gold ball is bonded in the center of the pad, and the gold ball is welded into a gold cake; (3) Use a wedge welding machine to weld the gold cake, align the welding point of the wedge welding cutter with the neck of the gold cake, pull the wire upward to form a wire arc, and then contact other welding points for welding.

[0010] Preferably, in step (1), the chip is cleaned using a plasma cleaning device.

[0011] Preferably, in step (2), the temperature of the ball bonding machine is 160-190°C.

[0012] Preferably, in step (2), the thickness of the gold cake is 10-15 μm, and the thickness of the gold cake is 50-60 μm.

[0013] Preferably, in step (2), the distance between the center of the wedge welding point and the center of the top surface of the gold cake is less than or equal to 10 μm.

[0014] Preferably, in step (3), the temperature of the wedge bonder is 100-130°C.

[0015] 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 and a wire bonding process, the 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 is located in the bonding window and combined with the Pad; a welding gold wire, one end of the welding gold wire is 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 splitter to the gold cake, which can avoid the welding splitter from contacting the Pad and the passivation layer, and avoids the welding splitter from pressing the Pad and the passivation layer, thereby avoiding the Pad and the passivation layer from being damaged. The wire bonding structure of the present invention avoids the defect that the chip and the passivation layer are easily damaged and cracked during the welding process, thereby improving product reliability and product yield.

[0016] 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

[0017] Figure 1 It is a structural schematic diagram of an embodiment of a welding wire bonding structure of the present invention; Figure 2 It is a schematic structural diagram of an embodiment of the chip of the present invention. DETAILED DESCRIPTION

[0018] 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.

[0019] like Figure 1 , Figure 2 As shown, the wire bonding structure of the present invention includes: a chip 10, the chip 10 includes a Pad 11 and a passivation layer 12, and the passivation layer 12 covers the Pad 11. A concave bonding window 13 is formed on the passivation layer 12, and the bonding window 13 extends only to the Pad 11, so that the Pad 11 is exposed in the bonding window 13.

[0020] In the present application, the bonding window 13 may be formed on the passivation layer 12 in a manner commonly used in the art, and no specific limitation is made herein.

[0021] The wire bonding structure of the present invention further includes a gold cake 20 , which is located in the bonding window 13 and combined on the Pad 11 .

[0022] 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 chopper 31 is directly in contact with the top surface of the gold cake 20 for welding, and the welding chopper does not contact the passivation layer 12, which can avoid the welding chopper pressing the passivation layer 12, thereby avoiding the passivation layer 12 from being damaged.

[0023] 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.

[0024] The welding wire bonding structure of the present invention further includes a welding gold wire 30, one end of the welding gold wire 30 is welded to the gold cake 20, and the other end of the welding gold wire 30 is welded to other welding points. During welding, the welding point of the welding chopper 31 is directly contacted and welded with the center of the top plane of the gold cake 20, and the welding chopper 31 does not contact the Pad 11, so that the welding chopper can avoid pressing the Pad 11, thereby preventing the Pad 11 from being damaged.

[0025] The distance 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 10 μm, so that the gold cake 20 can be effectively welded to form an effective wire arc, and it can be ensured that the welding blade 31 will not contact the passivation layer 12 and will not damage the passivation layer 12.

[0026] 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 ensure that the gold cake 20 can be effectively welded to Pad 11.

[0027] In addition, the diameter of the bonding window 13 is 5-10 μm larger than the diameter of the gold cake 20, so that a gap can be formed between the gold cake 20 and the bonding window 13 to avoid contact between the welding blade 31 and the passivation layer 12 during welding, and to avoid the welding blade 31 pressing against the passivation layer 12, thereby avoiding damage to the passivation layer 12.

[0028] The welding wire bonding structure of the present invention forms a concave bonding window 13 on the passivation layer 12, exposes the Pad 11 in the bonding window 13, welds the gold cake 20 on the exposed Pad 11, and directly welds the welding splitter 31 to the gold cake 20, which can avoid the welding splitter 31 from contacting the Pad 11 and the passivation layer 12, and avoids the welding splitter 31 from pressing the Pad 11 and the passivation layer 12, thereby avoiding the Pad 11 and the passivation layer 12 from being damaged. The welding wire bonding structure of the present invention avoids the defect that the chip 10 and the passivation layer 12 are easily damaged and cracked during the welding process, thereby improving product reliability and product yield.

[0029] The wire bonding process of the wire bonding structure of the present invention comprises the following steps: (1) A bonding window 13 is formed on the passivation layer 12 of the chip 10 , the Pad 11 is exposed in the bonding window 13 , and the chip 10 is cleaned.

[0030] In the present application, the bonding window 13 may be formed on the passivation layer 12 in a manner commonly used in the art, and no specific limitation is made herein.

[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 smoothly and effectively implemented.

[0033] (2) A ball bonder is used to bond a gold ball to Pad 11 of chip 10 . The gold ball is bonded at the center of Pad 11 , and the gold ball is welded into a gold wafer 20 .

[0034] Specifically, a gold ball is placed in the bonding window 13, and the gold ball contacts the Pad 11 exposed in and outside the bonding window 13; a ball welding machine is used to weld the gold ball on the Pad 11, and the gold ball is squeezed and welded to form a gold cake 20. The bottom surface of the gold cake 20 is welded to the Pad 11, and the top surface of the gold cake 20 exposes the welding window 13, and the top surface of the gold cake 20 is higher than the top surface of the passivation layer 12.

[0035] The temperature of the ball bonder is 160-190℃. Within this temperature range, the activation degree of the combination of 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 directly in 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 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 distance between the center of the welding point of the wedge welding knife 31 and the center of the top surface of the gold cake 20 is less than or equal to 10 μm, 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 knife 31 will not contact the passivation layer 12 and will not damage 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 welding machine is 100-130° C. Within this temperature range, it can be ensured that the gold ball will not melt into a liquid state, 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 in the bonding window 13, welds the gold cake 20 on the exposed Pad 11, and directly welds the welding splitter 31 to the gold cake 20, which can avoid the welding splitter 31 from contacting the Pad 11 and the passivation layer 12, and avoids the welding splitter 31 from pressing the Pad 11 and the passivation layer 12, thereby avoiding the Pad 11 and the passivation layer 12 from being damaged. The wire bonding process of the present invention can avoid the defect that the chip 10 and the passivation layer 12 are easily damaged and cracked 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 aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein by 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, wherein a concave bonding window is formed on the chip, and an exposed pad is provided in the bonding window; A gold cake, the gold cake is located in the bonding window and combined on the Pad; A gold wire is welded, wherein one end of the gold wire is welded to the gold cake.

2. The wire bonding process according to claim 1, characterized in that: The top surface of the gold cake extends out of the bonding window, and the thickness of the gold cake is 10-15 μm.

3. The wire bonding process according to claim 1, characterized in that: The diameter of the gold cake is 50-60 μm.

4. The wire bonding process according to claim 1, characterized in that: 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.

5. A wire bonding process for a wire bonding structure according to any one of claims 1 to 4, characterized in that: The steps include: (1) Clean the chip; (2) Using a ball bonding machine to bond a gold ball to the pad of the chip, the gold ball is bonded in the center of the pad, and the gold ball is welded into a gold cake; (3) Use a wedge welding machine to weld the gold cake, align the welding point of the wedge welding cutter with the center of the top surface of the gold cake, pull the wire upward to form an arc, and then contact other welding points for welding.

6. The wire bonding process according to claim 5, characterized in that: The step (1) is to clean the chip using a plasma cleaning device.

7. The wire bonding process according to claim 5, characterized in that: In the step (2), the temperature of the ball bonding machine is 160-190°C.

8. The wire bonding process according to claim 5, characterized in that: In the step (2), the thickness of the gold cake is 10-15 μm, and the thickness of the gold cake is 50-60 μm.

9. The wire bonding process according to claim 5, characterized in that: In the step (2), the distance between the center of the welding point of the wedge welding tool and the center of the top surface of the gold cake is less than or equal to 10 μm.

10. The wire bonding process according to claim 5, characterized in that: In the step (3), the temperature of the wedge bonding machine is 100-130°C.

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