Gold wire ball wedge bonding method and 1.6t silicon optical module
By combining ball bonding and wedge bonding processes in the 1.6T silicon photonics module, gold wires are wedge bonded onto the PCB board and silicon photonics chip after gold balls are implanted, solving the problems of excessive gold wire length and unstable wedge bonding reliability, thus improving reliability and high-frequency performance.
Patent Information
- Application Number
- CN202511425334.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2025-12-05
- Estimated Expiration
- 2045-09-30
AI Technical Summary
The existing 1.6T silicon photonics module has a large parasitic inductance of gold wires, which leads to a decrease in high-frequency performance. Furthermore, the wedge bonding process is not reliable, and conventional ball bonding processes cannot increase the number of gold wires.
Gold balls are implanted on the RF pads of the PCB board and the silicon photonics chip using ball bonding technology. Then, a wedge bonding process is used to wedge one end of the gold wire onto the silicon photonics chip and the other end onto the gold ball implanted on the PCB board, avoiding direct contact with the rigid RF pads. The gold wire cutting and pressing operation is completed using the soft gold balls.
It significantly improves the reliability and high-frequency performance of gold wire, reduces the total length of gold wire, increases the gold wire diameter to 35μm, enhances strength and reliability, and solves the problem of unstable reliability when wedge soldered on PCB board.
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Figure CN120891597B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of optical modules, in particular to a gold wire ball wedge bonding method and a 1.6T silicon optical module. BACKGROUND
[0002] A mainstream scheme of a traditional 1.6T silicon optical module adopts a single-wave 200G design, and there are 8 paths, that is, 8x200G=1.6T. In the 1.6T silicon optical module, a double-gold-wire design is generally adopted between each RF pad of a PCB and each RF pad of a silicon optical chip, so as to reduce the parasitic inductance of the gold wire. The reason is that the parasitic inductance of two gold wires is half of that of one gold wire, and there are two bonding processes of the gold wire and the RF pad on the PCB or the silicon optical chip, which are ball bonding and wedge bonding.
[0003] The working principle of the ball bonding process is as follows: the gold wire passes through the capillary of the hollow clamp, the part of the gold wire that protrudes is melted through arc discharge, and is spheroidized under the action of surface tension, then the ball is pressed and welded to one RF pad of the silicon optical chip through the clamp, and after being pressed, the ball serves as the first welding point, then the bent gold wire is pulled out from the first welding point, is pulled up, and is pressed and welded to one RF pad of the PCB, to form the second welding point. In production and application, the ball bonding is usually repeated once at the second welding point to lock the ball of the gold wire, so that the gold wire is more firm at the second welding point, as shown in FIG. 1. Figure 1 The ball bonding has no direction restriction in the bonding process, the ball bonding process increases the bonding strength of the gold wire, the two gold wires are independent, and are approximately parallel.
[0004] Since the parasitic inductance of the gold wire is required to be as small as possible, and the width size of the currently designed RF pad is generally designed to be 140 μm in length and 70 μm in width due to problems such as parasitic capacitance, the ball bonding is affected by the size of the pad, the ball diameter of the gold wire bonding is generally 2-3 times the diameter of the gold wire, and the diameter of the gold wire is generally 25 μm, so the ball diameter is less than 60 μm, thereby reserving a safety distance of 10 μm. Therefore, the current scheme can only punch two gold wires for each RF pad, and the number of gold wires cannot be increased. In addition, the ball bonding process requires that the gold wire must be pulled up after one welding, and the arc height of the gold wire is generally at least 75 μm, that is, at least 3 times the diameter of the gold wire. In addition, the thickness of the ball after one welding is generally 25 μm, so the overall arc height of the gold wire is more than 100 μm, which leads to a longer total length of the gold wire, a larger parasitic inductance, and a decline in high-frequency performance.
[0005] As shown in FIG. 2, the ball bonding process is not limited in direction, and the two gold wires are independent and approximately parallel. Figure 2As shown, the wedge soldering gold wire arc height can be less than 25μm, which can greatly reduce the total length of the gold wire and improve the high frequency performance, but the wedge soldering method uses physical pressure to break the gold wire, and since the RF pad of the PCB board is a hard RF pad, the breaking point of the wedge soldering gold wire is prone to cracks, and is prone to failure during subsequent temperature cycling and other reliability screening, so the optical module industry does not use wedge soldering process (the reason is that the wedge soldering process is not stable in reliability), in order to avoid the failure caused by the breakage of the gold wire, the ball soldering process is currently basically used.
[0006] The flat surface of the cleaver: The flat surface of the cleaver is generally in the front of the cleaver, which is used for the installation and positioning of the cleaver, and it is related to the design of the transducer. Most machines use screws to fix the cleaver on the amplitude lever of the transducer from the front, and the flat surface of the cleaver faces forward during fixing. The foot of the cleaver: The lower end of the cleaver and the bottom of the cleaver are the most critical part, which is the bonding site. The lower end of the cleaver is also called "foot", the front of which is the toe, and the back of which is the heel. The radius of the toe and the heel of the cleaver is very critical. The heel must have a relatively large radius to prevent cracks at the root of the first welding point during bonding, but the radius needs to be smaller after the second welding point is bonded to utilize the wire pulling. Cleaver bottom structure: For ribbon leads, it is best to use a cleaver with a groove between the bottom and the small gap for wire feeding. This gap provides some space for the cleaver to rise when an arc is drawn, preventing cracks at the heel of the first welding bonding point. SUMMARY
[0007] The technical problem to be solved by the present application is to provide a gold wire ball wedge soldering bonding method and a 1.6T silicon optical module to overcome the shortcomings of the prior art.
[0008] The technical solution for solving the above technical problem is as follows:
[0009] A gold wire ball wedge soldering bonding method, comprising the following steps:
[0010] First, a ball soldering process is used to plant a first gold ball on the RF pad of the PCB board;
[0011] Then, a wedge soldering process is used to wedge one end of the gold wire on one RF pad of the silicon optical chip, and the other end is pulled up and then wedge soldered on the first gold ball planted on the RF pad of the PCB board.
[0012] The beneficial effects of the present application are:
[0013] Since the first gold ball is relatively soft and has a certain thickness, the wedge soldering process can not contact the silicon optical chip when the gold wire is broken by pressure, and the operation of cutting and breaking the gold wire can be completed, so as to avoid damage or damage to the silicon optical chip, and greatly improve the reliability;
[0014] When the gold wire is pulled, force is applied to the first gold ball, and the first gold ball and the RF pad are welded by a ball welding process, so the welding area of the first gold ball and the RF pad is large, so that the gold layer of the RF pad on the PCB is not brought up and falls off from the body, and the gold wire wedge bonding method solves the problems of the long total length of the gold wire and the instability of the wedge welding on the RF pad of the PCB.
[0015] The ball welding is affected by the RF pad size and the gold ball, so that the maximum gold wire diameter is generally 25 mu m, and the minimum gold ball diameter is 50 mu m, because the gold ball cannot exceed the RF pad and a certain safety distance is left, and after the ball wedge welding, the maximum gold wire diameter can be 35 mu m, the thicker the gold wire diameter, the stronger the force, the better the reliability, and the better the high frequency performance.
[0016] On the basis of the above technical scheme, the application can also be improved as follows.
[0017] Further, the welding area of the first gold ball and the RF pad on the PCB is 50 mu m to 60 mu m after the gold wire is wedge welded with the first gold ball.
[0018] Further, the thickness of the first gold ball is 25 mu m to 40 mu m after the gold wire is wedge welded with the first gold ball.
[0019] Further, two first gold balls are planted on the RF pad of the PCB, the length of the RF pad on the PCB is 140 mu m, the width is 70 mu m, and the maximum diameter of the gold wire is 35 mu m.
[0020] Further, the ball welding process is used to plant a second gold ball on the RF pad of the silicon optical chip and a first gold ball on the RF pad of the PCB, and then the wedge welding process is used to wedge the one end of the gold wire on the planted second gold ball on the RF pad of the silicon optical chip, and the other end is pulled up and then wedge welded on the planted first gold ball on the RF pad of the PCB.
[0021] The above further beneficial effects are as follows:
[0022] First, a first gold ball is planted on the RF pad of the PCB, and a second gold ball is planted on the RF pad of the silicon optical chip, and then gold wire wedge welding is performed on the first gold ball and the second gold ball, because the first gold ball and the second gold ball are relatively soft and have a certain thickness, so that the wedge welding process can not touch the hard RF pad on the PCB or the silicon optical chip when the gold wire is cut and pressed and pulled off, and the operation of cutting and pressing and pulling off the gold wire is completed, which greatly improves the reliability.
[0023] When the gold wire is pulled, force is applied to the first gold ball and the second gold ball, and the first gold ball and the second gold ball are welded to the RF pad by a ball welding process, the welding area of the first gold ball to the RF pad is large, and the welding area of the second gold ball to the RF pad is large, so that the gold layer on the RF pad of the PCB or the silicon optical chip itself is not brought up and falls off from the body, the existing wedge welding process is directly welded to the RF pad on the PCB and the silicon optical chip, when the gold wire is pulled off, the contact area of the gold wire with the RF pad on the PCB and the silicon optical chip is very small, generally less than 10 μm, and the pulling-off process is a gradual lifting process, which is easy to cause the gold layer on the RF pad of the PCB or the silicon optical chip itself to be brought up and fall off from the body; the gold wire ball wedge welding bonding method solves the problems of the total length of the gold wire being too long and the reliability of the wedge welding on the RF pad in the PCB being unstable.
[0024] The ball welding is affected by the RF pad size and the gold ball, so that the maximum gold wire diameter is generally 25 μm, and the minimum gold ball diameter is 50 μm, because the gold ball cannot exceed the RF pad and a certain safety distance is required, and after the ball wedge welding, the maximum gold wire diameter can be 35 μm, the thicker the gold wire diameter, the stronger the force, the better the reliability, and the better the high-frequency performance.
[0025] Further, the welding area of the first gold ball to the RF pad on the PCB after the gold wire is wedge welded with the first gold ball is 50 μm to 60 μm, and the welding area of the second gold ball to the RF pad on the silicon optical chip after the gold wire is wedge welded with the second gold ball is 50 μm to 60 μm.
[0026] Further, the thickness of the first gold ball after the gold wire is wedge welded with the first gold ball is 25 μm to 40 μm, and the thickness of the second gold ball after the gold wire is wedge welded with the second gold ball is 25 μm to 40 μm.
[0027] Further, two first gold balls are planted on the RF pad of the PCB; the length of the RF pad on the PCB is 140 μm, and the width is 70 μm; the maximum diameter of the gold wire is 35 μm, two second gold balls are planted on the RF pad of the silicon optical chip, the length of the RF pad on the silicon optical chip is 140 μm, and the width is 70 μm.
[0028] Based on the above technical solution, the application also provides a 1.6T silicon optical module, which is bonded by the gold wire ball wedge welding bonding method of some of the above structures.
[0029] The above further beneficial effects are that the total length of the gold wire is too long, and the reliability of the wedge welding on the RF pad in the PCB is unstable, because the maximum diameter of the gold wire can be 35 μm, the thicker the gold wire diameter, the stronger the force, the better the reliability, and the better the high-frequency performance.
[0030] Based on the above technical solution, the application further provides a 1.6T silicon optical module, which is bonded by the method for bonding gold wire ball wedge bonding of the additional part.
[0031] The above further beneficial effect is that the problem of too long total length of gold wire is solved, and the problem of unstable reliability of wedge bonding on the RF pad in the PCB is solved. Since the diameter of the gold wire can be up to 35μm, the thicker the diameter of the gold wire, the stronger the force, the better the reliability, and the better the high-frequency performance. BRIEF DESCRIPTION OF DRAWINGS
[0032] Figure 1 is a schematic diagram of the ball bonding process in the prior art;
[0033] Figure 2 is a schematic diagram of the wedge bonding process in the prior art;
[0034] Figure 3 is a structural diagram of a 1.6T silicon optical module using the first bonding structure;
[0035] Figure 4 is a flowchart of the first bonding structure;
[0036] Figure 5 is a structural diagram of a 1.6T silicon optical module using the second bonding structure;
[0037] Figure 6 is a flowchart of the second bonding structure;
[0038] Figure 7 is a top view of a 1.6T silicon optical module using the second bonding structure.
[0039] In the drawings, the components represented by each reference numeral are listed as follows:
[0040] 1, PCB, 2, first gold ball, 3, gold wire, 4, silicon optical chip, 5, second gold ball. DETAILED DESCRIPTION
[0041] The principles and features of the application are described below in conjunction with the drawings, and the examples are only used to explain the application and not to limit the scope of the application.
[0042] Example 1
[0043] As shown in Figure 3 , Figure 4 , a method for bonding gold wire ball wedge bonding includes the following steps:
[0044] First, a first gold ball 2 is planted on the RF pad of the PCB 1 using the ball bonding process;
[0045] Then, the one end of the gold wire 3 is wedge-bonded on one RF pad of the silicon optical chip 4, and the other end is pulled up and then wedge-bonded on the first gold ball 2 planted on the RF pad of the PCB board 1.
[0046] When the RF pad of the silicon optical chip 4 is slightly higher than the RF pad of the PCB board 1 (this situation exists due to the thickness tolerance of the PCB board 1), and the RF pad of the selected silicon optical chip 4 has a strong direct gold wire wedge-bonding force, the RF pad of the silicon optical chip 4 can be planted without a ball (part of the chip can be directly wedge-bonded by using a special process), and the first gold ball 2 is planted on the RF pad of the PCB board 1 first, and then the gold wire is wedge-bonded on the first gold ball 2. Since the first gold ball 2 is relatively soft and has a certain thickness, the wedge-bonding process can not contact the silicon optical chip 4 when cutting and pulling off the gold wire 3, and the operation of cutting and pulling off the gold wire 3 can be completed, so as to avoid damage or damage to the silicon optical chip 4 and greatly improve the reliability.
[0047] When the gold wire is pulled, the force acts on the first gold ball 2, and the first gold ball 2 and the RF pad are welded by using a ball bonding process. The welding area of the first gold ball 2 and the RF pad is large, so that the gold layer of the RF pad on the PCB board 1 is not brought up and falls off from the body. The gold wire ball wedge bonding method solves the problems of the total length of the gold wire being too long and the reliability of the wedge bonding on the RF pad of the PCB board 1 being unstable.
[0048] The ball bonding is affected by the size of the RF pad and the gold ball, so that the maximum diameter of the gold wire 3 is generally 25 μm, and the minimum diameter of the gold ball is 50 μm. The reason is that the gold ball cannot exceed the RF pad and a certain safety distance is left. After using the ball wedge bonding, the maximum diameter of the gold wire 3 can be 35 μm. The thicker the diameter of the gold wire 3, the stronger the force, the better the reliability, and the better the high-frequency performance.
[0049] Embodiment 2
[0050] As shown in Figure 3 , this embodiment is a further improvement based on embodiment 1, and the specific improvements are as follows:
[0051] The welding area of the first gold ball 2 and the RF pad on the PCB board 1 is 50 μm to 60 μm after the gold wire 3 is wedge-bonded with the first gold ball 2. The thickness of the first gold ball 2 is 25 μm to 40 μm after the gold wire 3 is wedge-bonded with the first gold ball 2.
[0052] Furthermore, two first gold balls 2 are planted on the RF pad of the PCB board 1. The length of the RF pad on the PCB board 1 is 140 μm, the width is 70 μm, and the maximum diameter of the gold wire 3 is 35 μm.
[0053] Embodiment 3
[0054] As shown in Figure 5 ,Figure 6 、 Figure 7 As shown in FIG. 1, a gold wire ball wedge bonding method comprises the following steps:
[0055] First, a second gold ball 5 is planted on the RF pad of the silicon optical chip 4 and a first gold ball 2 is planted on the RF pad of the PCB board 1 by using a ball bonding process, and then one end of the gold wire 3 is wedge-bonded on the second gold ball 5 planted on the RF pad of the silicon optical chip 4, and the other end is pulled up and then wedge-bonded on the first gold ball 2 planted on the RF pad of the PCB board 1.
[0056] First, a first gold ball 2 is planted on the RF pad of the PCB board 1 and a second gold ball 5 is planted on the RF pad of the silicon optical chip 4, and then gold wire wedge bonding is performed on the first gold ball 2 and the second gold ball 5. Since the first gold ball 2 and the second gold ball 5 are relatively soft and have a certain thickness, the wedge bonding process can not contact the hard RF pad on the PCB board 1 or the silicon optical chip 4 when the gold wire 3 is cut and pulled off, and the operation of cutting and pulling off the gold wire 3 is completed, greatly improving the reliability.
[0057] When the gold wire is pulled, the force acts on the first gold ball 2 and the second gold ball 5, and the first gold ball 2 and the second gold ball 5 are bonded with the RF pad by using a ball bonding process. The bonding area of the first gold ball 2 with the RF pad is large, and the bonding area of the second gold ball 5 with the RF pad is large, so that the gold layer on the RF pad itself on the PCB board 1 or the silicon optical chip 4 is not lifted and falls off from the body. The existing wedge bonding process is directly bonded with the RF pad on the PCB board 1 and the silicon optical chip 4. When the gold wire is pulled off, since the contact area of the gold wire with the RF pad on the PCB board 1 and the silicon optical chip 4 is very small, generally less than 10 μm, and the pulling-off process is a gradual lifting process, it is easy to cause the gold layer on the RF pad itself on the PCB board 1 or the silicon optical chip 4 to be lifted and fall off from the body. The gold wire ball wedge bonding method solves the problem of too long total length of the gold wire and the problem of unstable reliability of wedge bonding on the RF pad of the PCB board 1.
[0058] The ball bonding is affected by the size of the RF pad and the gold ball, so that the maximum diameter of the gold wire 3 is generally 25 μm and the minimum diameter of the gold ball is 50 μm. The reason is that the gold ball cannot exceed the RF pad and a certain safety distance must be left. After using ball wedge bonding, the maximum diameter of the gold wire 3 can be 35 μm. The thicker the diameter of the gold wire 3, the stronger the force, the better the reliability, and the better the high-frequency performance.
[0059] Example 4
[0060] As shown in FIG. 1, a gold wire ball wedge bonding method comprises the following steps: Figure 5 、 Figure 7 As shown in FIG. 1, a gold wire ball wedge bonding method comprises the following steps:
[0061] The bonding area of the first gold ball 2 and the RF pad on the PCB 1 after the wedge bonding of the gold wire 3 and the first gold ball 2 is 50-60 μm, and the thickness of the first gold ball 2 after the wedge bonding of the gold wire 3 and the first gold ball 2 is 25-40 μm;
[0062] The bonding area of the second gold ball 5 and the RF pad on the silicon optical chip 4 after the wedge bonding of the gold wire 3 and the second gold ball 5 is 50-60 μm, and the thickness of the second gold ball 5 after the wedge bonding of the gold wire 3 and the second gold ball 5 is 25-40 μm.
[0063] Two first gold balls 2 are planted on the RF pad of the PCB 1, the length of the RF pad on the PCB 1 is 140 μm, and the width is 70 μm; the diameter of the gold wire 3 is 35 μm at most, and two second gold balls 5 are planted on the RF pad of the silicon optical chip 4, the length of the RF pad on the silicon optical chip 4 is 140 μm, and the width is 70 μm.
[0064] Example 5
[0065] As shown in Figure 3 , a 1.6T silicon optical module adopting the structure bonded by the gold wire ball wedge bonding method as described in Example 1 or 2.
[0066] Example 6
[0067] As shown in Figure 5 , Figure 7 , a 1.6T silicon optical module adopting the structure bonded by the gold wire ball wedge bonding method as described in Example 3 or 4.
[0068] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.
Claims
1. A method of wire ball wedge bonding, characterized by, It comprises the following steps: First, a first gold ball (2) is planted on the RF pad of the PCB board (1) by using ball welding process; Then, one end of the gold wire (3) is wedge-bonded on one RF pad of the silicon optical chip (4) by using wedge-bonding process, and the other end is pulled up and then wedge-bonded on one first gold ball (2) planted on the RF pad of the PCB board (1), the welding area of the first gold ball (2) and the RF pad of the PCB board (1) after the wedge-bonding of the gold wire (3) and the first gold ball (2) is 50-60 μm, the thickness of the first gold ball (2) after the wedge-bonding of the gold wire (3) and the first gold ball (2) is 25-40 μm, and the maximum diameter of the gold wire (3) is 35 μm.
2. The method of claim 1, wherein the gold wire wedge bonding method is characterized by, Two first gold balls (2) are planted on the RF pad of the PCB board (1), the length of the RF pad of the PCB board (1) is 140 μm, and the width is 70 μm.
3. The method of claim 1, wherein the gold wire wedge bonding method is characterized by, First, a second gold ball (5) is planted on the RF pad of the silicon optical chip (4) and a first gold ball (2) is planted on the RF pad of the PCB board (1) by using ball welding process, and then one end of the gold wire (3) is wedge-bonded on one second gold ball (5) planted on the RF pad of the silicon optical chip (4) by using wedge-bonding process, and the other end is pulled up and then wedge-bonded on one first gold ball (2) planted on the RF pad of the PCB board (1).
4. The method of claim 3, wherein the gold wire wedge bonding method is characterized by, The welding area of the second gold ball (5) and the RF pad of the silicon optical chip (4) after the wedge-bonding of the gold wire (3) and the second gold ball (5) is 50-60 μm.
5. The method of claim 4, wherein the gold wire wedge bonding method is characterized by, The thickness of the second gold ball (5) after the wedge-bonding of the gold wire (3) and the second gold ball (5) is 25-40 μm.
6. The method of claim 4, wherein the gold wire wedge bonding method is characterized by, Two first gold balls (2) are planted on the RF pad of the PCB board (1), the length of the RF pad of the PCB board (1) is 140 μm, and the width is 70 μm; two second gold balls (5) are planted on the RF pad of the silicon optical chip (4), and the length of the RF pad of the silicon optical chip (4) is 140 μm, and the width is 70 μm.
7. A 1.6T silicon optical module characterized by, The structure bonded by the gold wire ball wedge-bonding bonding method as claimed in claim 1 or 2.
8. A 1.6T silicon optical module characterized by, The structure bonded by the gold wire ball wedge-bonding bonding method as claimed in any one of claims 3-6.
Citation Information
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