Method for wire bonding of semiconductor devices

Abstract

The present invention discloses a fixture for wire bonding of semiconductor devices and a wire bonding method. The fixture includes a flexible film, and the flexible film includes: a front side of the film, the peel adhesion between the front side of the film and the product bonding surface meeting the processing requirements; a back side of the film, the peel adhesion between the back side of the film and the hot stage bonding surface being greater than the processing requirements. The clamping method provided by the present invention can reduce the time for product clamping and switching, improve the assembly efficiency, reduce the fatigue strength and improve the assembly quality. It is measured that the assembly efficiency is comprehensively increased by 2 times or more.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-assembly process, and in particular relates to a clamp for wire bonding of semiconductor devices and a wire bonding method. Background Art

[0002] With the high-density development of microwave integrated products, the demand for tiny modules has increased by orders of magnitude. In the existing wire bonding process of microwave integrated products, the product must first be clamped and fixed on a hot table to ensure that the product is in a static state during the welding wire.

[0003] A common clamping method in the wire bonding process is to use the reed (metal) and tunable pressure sheet (metal) and screw device provided by the hot stage to mechanically clamp and fix the product, but only single-piece clamping cycle operation is possible; another common clamping method in the wire bonding process is to use a customized fixture for array clamping and fixing, but it can only be used for one or a type of products with the same appearance.

[0004] However, for products such as micro modules (≤3×3×0.38mm) that are smaller, thinner, and have irregular shapes, the traditional clamping method used in the wire bonding process will result in a decrease in assembly efficiency and pass rate due to the inability to clamp (caused by the device structure) and the high clamping switching frequency. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a clamp and a wire bonding method for semiconductor device wire bonding. Compared with the traditional clamping method, the flexible clamping structure is adopted in the structure, which has the advantages of high clamping efficiency and no restrictions on product size.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A clamp for wire bonding of a semiconductor device, the clamp comprising a flexible film, the flexible film comprising:

[0008] The front side of the film, the peeling adhesion between the front side of the film and the adhesive surface of the product meets the processing requirements;

[0009] The back side of the film, the peeling adhesion between the back side of the film and the adhesive surface of the hot stage is greater than the processing requirement.

[0010] Furthermore, the flexible film is made of a material having a temperature resistance of more than 200°C.

[0011] Furthermore, the flexible film includes a flexible adhesive film.

[0012] Further, the peel adhesion between the front side of the film and the bonding surface of the product meets the processing requirements, including that the peel adhesion between the front side of the film and the bonding surface of the product is between 25 gf / 25 mm and 35 gf / 25 mm; the peel adhesion between the back side of the film and the bonding surface of the hot stage is greater than the processing requirements, including that the peel adhesion between the back side of the film and the bonding surface of the hot stage is greater than 700 gf / 25 mm.

[0013] Further, a protective film is coated on both the front and back sides of the flexible film.

[0014] The present invention also provides a method for wire bonding of semiconductor devices. This method uses any one of the aforementioned fixtures for wire bonding of semiconductor devices to perform wire bonding, and the method includes:

[0015] Attach the flexible film to the bonding surface of the hot stage and discharge the air between the flexible film and the bonding surface of the hot stage;

[0016] Bond and place the product to be welded on the front side of the film;

[0017] Perform wire bonding operation after being heat-stable.

[0018] Further, when bonding the products to be welded, they are evenly arrayed and bonded on the front side of the film with at least a 2-mm gap between adjacent products to be welded.

[0019] Further, the specific steps of performing the wire bonding operation include:

[0020] Weld the wires on the same side of all the products to be welded in sequence according to the order of the selected welding method;

[0021] After completing the welding of the wires on one side of the products to be welded, adjust the direction and weld the wires on the other side until all the wire welds are completed.

[0022] Further, before the step of attaching the flexible film to the bonding surface of the hot stage, it also includes wiping and cleaning the surface of the hot stage with a cleaner.

[0023] Further, the specific steps of discharging the air between the flexible film and the bonding surface of the hot stage include:

[0024] Extrude the air between the flexible film and the bonding surface of the hot stage with a straightedge to make the back side of the flexible film flatly attached to the hot stage surface.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The present invention uses film pasting and clamping, which is not limited by the shape and size of the product, solves the problem of inability to clamp micro-module products, and at the same time solves the problem of multiple repeated clamping caused by wire and tool changing of single-set equipment, saving the product loading and unloading time.

[0027] (2) The present invention adopts an array arrangement when performing wire bonding processing on the products to be welded, which can meet the needs of streamlined processing and conform to the operational characteristics of wire bonding. It can effectively reduce the time for rotating the hot plate, shorten the micro-movement distance, increase the processing speed, and reduce the total bonding time for each product processing.

[0028] (3) The present invention adopts the same-direction zone processing, which can reduce the difficulty of the operator to remember the connection relationship of the product, thereby reducing the misalignment and leakage of wires, and improving product quality and wire welding arc consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a fixture for wire bonding of a semiconductor device provided by an embodiment of the present invention;

[0030] Figure 2 It is a flowchart of a semiconductor device wire bonding method provided by an embodiment of the present invention;

[0031] Figure 3 The present invention is a schematic diagram of a pipeline processing method for wire bonding of a semiconductor device provided by an embodiment of the present invention.

[0032] Among them, 1-flexible film, 2-product to be welded, 3-heating stage. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0035] A common clamping method in the wire bonding process is to use the reed (metal) and tunable pressure sheet (metal) and screw device provided by the hot stage to mechanically clamp and fix the product, but only single-piece clamping cycle operation is possible; another common clamping method in the wire bonding process is to use a customized fixture for array clamping and fixing, but it can only be used for one or a type of products with the same appearance.

[0036] For products such as tiny modules (≤3×3×0.38 mm) with smaller, thinner, and irregular (non - regular shape) exteriors, the clamping method in the traditional wire bonding process will lead to a decrease in assembly efficiency and first - pass yield due to inability to clamp (caused by the device structure) and high clamping switching frequency.

[0037] To solve the above - mentioned technical problems, the following various embodiments of the fixture and wire bonding method for semiconductor device wire bonding of the present invention are proposed.

[0038] Embodiment 1

[0039] Refer to Figure 1 As shown in Figure 1 is a schematic diagram of a fixture for semiconductor device wire bonding provided in this embodiment. This fixture uses a flexible film as the structural support for the entire clamping mode. The flexible film includes a film front surface and a film back surface.

[0040] Among them, the peel adhesion between the film front surface and the product bonding surface meets the processing requirements; the peel adhesion between the film back surface and the bonding surface of the hot stage 3 is greater than the processing requirements. In this embodiment, the film back surface of the flexible film 1 needs to be flatly attached to the surface of the hot stage 3 without air bubble residues, and the peel adhesion requirement for the bonding surface with the hot stage 3 is greater than 700 gf / 25 mm. The peel adhesion requirement for the bonding surface between the film front surface of the flexible film 1 and the product is 30 (±5) gf / 25 mm.

[0041] It should be noted that when the film back surface is flatly attached to the surface of the hot stage 3, the product to be welded 2 can be flatly attached to the film front surface, and micro - movement can be reduced during the mass production of the wire bonding process, improving the processing speed.

[0042] It should also be noted that when the peel adhesion requirement for the bonding surface between the film back surface and the hot stage 3 is greater than 700 gf / 25 mm, the flexible film 1 can be effectively attached to the surface of the hot stage 3, avoiding displacement during the wire bonding process, which may increase the micro - movement distance and affect the efficiency of the entire processing procedure. And the peel adhesion requirement for the bonding surface between the film front surface of the flexible film 1 and the product is between 25 gf / 25 mm and 35 gf / 25 mm. If the peel adhesion between the film front surface of the flexible film 1 and the product bonding surface exceeds 35 gf / 25 mm, it is not convenient for the installation and disassembly of the product to be welded 2. If the peel adhesion between the film front surface of the flexible film 1 and the product bonding surface is less than 25 gf / 25 mm, displacement may occur during the wire bonding process due to unreliable bonding of the product to be welded 2, resulting in an increase in the micro - movement distance and affecting the efficiency of the entire processing procedure.

[0043] As an implementation method, in this embodiment, the flexible film 1 uses a flexible adhesive film, which requires a temperature resistance of more than 200 °C, double - sided adhesiveness and no glue hanging. Only when the temperature resistance meets the process requirements can it be used normally on the surface of the hot stage 3 to avoid situations such as damage to the adhesive film.

[0044] As an implementation manner, in this embodiment, a protective film is coated on both the front and back surfaces of the flexible film 1. Since the peel adhesion of the bonding surface between the back surface of the flexible film 1 and the hot stage 3 and the adhesion between the front surface of the flexible film 1 and the product are required to be relatively high, coating a protective film for preservation can avoid the attachment of dust and impurities on the front and back surfaces of the flexible film 1, resulting in a decrease in adhesion and affecting the normal use during processing.

[0045] The fixture for semiconductor device wire bonding provided in this embodiment is not limited by the external dimensions of the product, solves the problem that small module products cannot be clamped, and at the same time solves the problem of multiple repeated clamping caused by wire and tool changing of a single set of equipment, saving the product loading and unloading time.

[0046] Embodiment 2

[0047] Refer to Figure 2 and Figure 3 As shown in Figure 2 is a flowchart of a semiconductor device wire bonding method provided in this embodiment, and as shown in Figure 3 is a schematic diagram of the flow processing of a semiconductor device wire bonding method provided in this embodiment.

[0048] In this embodiment, a flexible adhesive film is used as the structural support for the entire clamping mode.

[0049] The semiconductor device wire bonding method provided in this embodiment specifically includes the following steps:

[0050] Step S100: Attach the flexible film 1 to the bonding surface of the hot stage 3 and discharge the air between the bonding surface of the flexible film 1 and the hot stage 3. If there are air bubbles remaining between the flexible film 1 and the surface of the hot stage 3, it will cause the flexible film 1 not to be flattened. After bonding the product 2 to be welded, the product 2 to be welded is on planes at different heights, which will make it impossible to perform the wire bonding flow operation.

[0051] As an implementation manner, in this embodiment, discharging the air between the bonding surface of the flexible film 1 and the hot stage 3 specifically includes:

[0052] Use a straightedge to squeeze out the air between the bonding surface of the flexible film 1 and the hot stage 3, so that the back surface of the flexible film 1 is flatly attached to the surface of the hot stage 3.

[0053] As an implementation manner, before the step of attaching the flexible film 1 to the bonding surface of the hot stage 3, it further includes using a cleaner to wipe and clean the surface of the hot stage 3.

[0054] As an implementation manner, in this embodiment, a cleaner with low volatility, high cleanliness and basically harmless to the human body is used, such as alcohol, etc. In specific use, because the amount of alcohol used is small, the surface of the hot stage 3 can be wiped and cleaned with an alcohol swab.

[0055] Step S200: Adhere and place the product 2 to be welded on the front side of the film.

[0056] As an implementation method, in this embodiment, the products 2 to be welded are bonded to the front side of the film using the adhesive force of the front side of the film. When bonding, the products 2 to be welded are bonded in a uniform array with a gap of at least 2 mm between adjacent products 2 to be welded and placed on the front side of the film. Although the more products 2 to be welded are bonded on the front side of the entire film, the higher the efficiency of a single process, if the gap between adjacent products 2 to be welded is less than 2 mm, it is not convenient to disassemble after the processing is completed and may cause processing interference between modules. Therefore, bonding adjacent products 2 to be welded in a uniform array with a gap of at least 2 mm can be efficiently disassembled after the wire bonding process is completed, and the next batch of products 2 to be welded can be bonded, thereby improving the overall work efficiency.

[0057] Step S300: After the heat is stabilized, wire bonding is performed.

[0058] As an implementation method, the wire bonding operation in this embodiment specifically includes:

[0059] According to the order of the selected welding methods, all the lines on the same side of the products to be welded 2 are welded in sequence;

[0060] After completing the welding of the connection line on one side of the product 2 to be welded, adjust the direction to weld the connection line on the other side until all the connections are completed.

[0061] Generally, if Figure 3 The product to be welded 2 shown in the figure usually has four processed surfaces. During manual wire bonding, if the four sides of each product to be welded 2 are processed by conventional methods and then the next product to be welded 2 is replaced for further processing, the problem of wire misalignment and wire leakage will increase. Therefore, adopting the same direction and divided area processing can reduce the difficulty of the operator to remember the connection relationship of the product, thereby reducing wire misalignment and wire leakage, and further improving product quality and wire welding arc consistency.

[0062] It should be noted that the optional welding methods in this embodiment include but are not limited to wedge welding and ball welding. If wedge welding is adopted, the second welding point is located behind the first welding point in a straight line direction, and the advantage is that a tiny welding area can be processed; if ball welding is adopted, the second welding point can be in any direction of the first welding point, and the welding point is larger than the wedge welding point. When performing wire bonding processing, a suitable welding method can be selected according to actual needs.

[0063] Compared with the general method of single-piece clamping cycle operation using the reed (metal) and tunable pressing sheet (metal) and screw device provided by the hot plate to mechanically clamp and fix the product, the semiconductor device lead bonding method provided in this embodiment can save an average of 10 seconds per piece in product assembly and disassembly time and reduce the average bonding time by more than 60 seconds per piece according to comprehensive calculations.

[0064] The lead bonding method of the semiconductor device provided in this embodiment adopts an array arrangement when performing lead bonding processing on the product to be welded, which can meet the requirements of flow processing, conform to the operation characteristics of lead bonding, effectively reduce the time of the rotating hot stage, shorten the micro-movement distance, have a faster processing speed, and reduce the total bonding time for each product. This method adopts the same-direction sub-region processing, which can reduce the difficulty for the operator to remember the wire connection relationship of the product, thereby reducing wire errors and missing wires, and improving the product quality and the consistency of wire bonding arcs.

[0065] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for wire bonding of a semiconductor device, which uses a fixture for wire bonding of a semiconductor device to perform wire bonding, characterized in that, The fixture includes a flexible adhesive film, which is made of a material with a temperature resistance of over 200 °C. The flexible adhesive film includes: The front side of the film, the peel adhesion between the front side of the film and the bonding surface of the product meets the processing requirements, including that the peel adhesion between the front side of the film and the bonding surface of the product is between 25 gf / 25mm and 35 gf / 25mm; The back side of the film, the peel adhesion between the back side of the film and the bonding surface of the hot stage is greater than the processing requirements, including that the peel adhesion between the back side of the film and the bonding surface of the hot stage is greater than 700 gf / 25mm; The method for wire bonding of semiconductor devices includes: Attach the flexible adhesive film to the bonding surface of the hot stage and expel the air between the flexible adhesive film and the bonding surface of the hot stage; When bonding the products to be welded, place them in a uniform array with a gap of at least 2 mm between adjacent products to be welded on the front side of the film; After thermal stability is achieved, perform wire bonding operations.

2. The method for wire bonding of a semiconductor device according to claim 1, wherein The specific steps for performing wire bonding operations include: According to the order of the selected welding method, weld the wires on the same side of all products to be welded in sequence; After completing the welding of the wires on one side of the products to be welded, adjust the direction and weld the wires on the other side until all the wires are completed.

3. The method for wire bonding of a semiconductor device as claimed in claim 1, wherein Before the step of attaching the flexible adhesive film to the bonding surface of the hot stage, it also includes cleaning the surface of the hot stage with a cleaner.

4. The method for wire bonding of a semiconductor device according to claim 1, characterized in that, The specific steps for expelling the air between the flexible adhesive film and the bonding surface of the hot stage include: Use a straightedge to extrude the air between the flexible adhesive film and the bonding surface of the hot stage, so that the back side of the flexible adhesive film is flatly attached to the hot stage surface.

5. The method for wire bonding of a semiconductor device according to claim 1, wherein A protective film is coated on both the front and back sides of the flexible adhesive film.

Images