A silicone spraying process for preventing optocoupler electrical performance failure

Abstract

The present invention relates to a silicone spraying process for preventing optocoupler electrical performance failure, which is applied to an optocoupler. The optocoupler includes a chip and bonding wires. One end of the bonding wire is connected to the chip. The silicone spraying method includes: after obtaining the input signal of the chip welded with the bonding wire, spraying an appropriate amount of liquid silicone onto the chip surface; determining whether the glue spraying process is qualified through optical vision detection. If not, stop the machine and give an alarm. If so, perform high-temperature curing to form an insulating layer, and then transport the sprayed chip to the output end. The present invention is beneficial to solving the problems of short circuit and leakage caused by gold wire collapse, and improving the yield and working stability of optocouplers.

Description

Technical Field

[0001] The present invention relates to a silicone spraying process for preventing opto - electrical performance failure of opto - couplers, belonging to the field of electronic technology. Background Art

[0002] In most industries such as household appliances, automobiles, aerospace, etc., opto - couplers play an important role. However, the occurrence of opto - electrical performance failure of opto - couplers seriously affects the performance of products, and the failure of opto - electrical performance of opto - couplers is mainly caused by the collapse of the gold wires of opto - couplers.

[0003] Among them, the reasons for the collapse of the gold wires include: First, during the gold wire bonding process in the production process, spot checks on the gold wire welding situation are carried out. When employees draw samples by hand and observe them under a magnifying glass, for example, when taking the sample close to the inside of the bracket, the finger sleeve is likely to touch the outermost row of gold wires of the opto - coupler, resulting in the collapse of the gold wires; Second, during the process of arranging and stacking the IR chip and the PT chip, the machine jitters too much, resulting in the collapse of the gold wires; Third, the positioning posts of the pressing equipment are too high, resulting in too high a jitter frequency during the pressing process, and then resulting in the collapse of the gold wires; Fourth, adjust the wire bonding linearity of the gold wire to increase the distance between the gold wire and the chip. In response to the above problems, some people in the industry have solved this problem from aspects such as optimizing the machine working parameters, optimizing the wire bonding shape, strengthening the production specifications, and changing the wire bonding material. However, these measures only reduce the defective rate of the collapsed gold wires and cannot prevent the short - circuit and leakage caused by the collapsed gold wires.

[0004] During the existing opto - coupler production process, due to machine reasons, human reasons, material reasons, etc., it is always inevitable to have a short - circuit phenomenon caused by the collapse of the gold wires. At the same time, the current inspection of collapsed wires in the industry is mainly X - ray detection. Because the detection efficiency of the X - ray detector is very low, the industry generally only uses it for spot checks of samples and cannot completely screen out the defective products with collapsed wires in the whole batch of products. Summary of the Invention

[0005] The present invention provides a silicone spraying process for preventing opto - electrical performance failure of opto - couplers, aiming to solve at least one of the technical problems existing in the prior art.

[0006] The technical solution of the present invention relates to a silicone spraying method, which is characterized in that it is applied to an opto - coupler. The opto - coupler includes a chip and a bonding wire, and one end of the bonding wire is connected to the chip. The method according to the present invention includes the following steps:

[0007] S100. After obtaining the input signal of the chip welded with the bonding wire;

[0008] S200. Spray an appropriate amount of liquid silicone onto the surface of the chip;

[0009] S300. Determine whether the glue spraying process is qualified through optical vision inspection; if not, stop the machine and give an alarm; if so, perform high-temperature curing to form an insulating layer, and then transport the sprayed chip to the output end.

[0010] Further, in the step S300, a CCD camera is used for automatic on-line vision inspection.

[0011] Further, in the step S300, baking at 150 degrees Celsius for 2 hours is used for high-temperature curing.

[0012] Further, in the step S200, silicone is sprayed on the working area of the chip.

[0013] Further, in the step S200, the air pressure intensity is adjusted according to the detection data of the pressure sensor and the solenoid valve to control the silicone spraying amount.

[0014] Further, the following steps are also included:

[0015] S400. Press-fit the IR chips and PT chips that are both sprayed with insulating layers.

[0016] The technical solution of the present invention also relates to a silicone spraying control system, which is connected to a silicone machine. It is characterized in that the system includes a computer device, and the computer device controls the silicone machine to execute the silicone spraying method of the above-mentioned embodiments of the present invention.

[0017] The technical solution of the present invention also relates to an optocoupler, which is manufactured by using the silicone spraying method of the above-mentioned embodiments of the present invention.

[0018] Further, one side surface of the chip connected with the bonding wire is covered with an insulating layer.

[0019] Further, the thickness of the insulating layer ranges from 0.07 mm to 0.08 mm.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention proposes a silicone spraying process for preventing optocoupler electrical performance failure, which is beneficial to solving the problems of short-circuit leakage caused by gold wire collapse and improving the quality of optocouplers. Spraying silicone on the chip after wire bonding makes an insulating layer form on the chip surface. When gold wire collapse occurs, the bonding wire contacts the silicone insulating layer, which is beneficial to preventing the short-circuit leakage problem caused by the contact between the bonding wire and the chip, effectively avoiding the optocoupler electrical performance failure phenomenon caused by gold wire collapse, and improving the yield rate and working stability of optocouplers. Using the CCD automatic on-line detection method, compared with the traditional quality detection method with low efficiency and uncontrollable accuracy, it can achieve full inspection of products and is beneficial to ensuring production efficiency. Description of the Drawings

[0022] Figure 1 It is a top view of the structure of the chip of the optocoupler according to an embodiment of the present invention.

[0023] Figure 2 It is a front view of the structure of the chip of the optocoupler according to an embodiment of the present invention.

[0024] Figure 3 It is a collapse line diagram of the unsprayed glue optocoupler according to an embodiment of the present invention.

[0025] Figure 4 It is a collapse line diagram of the sprayed glue optocoupler according to an embodiment of the present invention.

[0026] Figure 5a It is a process flow diagram of the silicone spraying method according to an embodiment of the present invention.

[0027] Figure 5b It is a schematic diagram of the dispensing positioning operation of the silicone spraying method according to an embodiment of the present invention.

[0028] Figure 6 It is a physical diagram of the unsprayed glue chip according to an embodiment of the present invention.

[0029] Figure 7 It is a physical diagram of the sprayed glue chip according to an embodiment of the present invention.

[0030] Figure 8 It is a test diagram of the insulation layer thickness of the sprayed glue chip according to an embodiment of the present invention.

[0031] Figure 9 It is an X-ray diagram after the collapse of the unsprayed glue optocoupler according to an embodiment of the present invention.

[0032] Figure 10 It is an X-ray diagram after the collapse of the sprayed glue optocoupler according to an embodiment of the present invention. Detailed implementation manners

[0033] Hereinafter, the concept, specific structure and technical effects of the present invention will be clearly and completely described in conjunction with the embodiments and the drawings, so as to fully understand the purpose, solution and effects of the present invention.

[0034] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. The singular forms of "a", "the", and "said" used in this article are also intended to include the plural forms, unless the context clearly indicates otherwise. In addition, unless otherwise defined, all technical and scientific terms used in this article have the same meaning as commonly understood by those skilled in the technical field of this invention. The terms used in the description of this article are only for describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this article includes any combination of one or more of the related listed items.

[0035] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from each other. For example, without departing from the scope of this disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element. The use of any and all examples or exemplary language ("for example", "such as", etc.) provided in this article is only intended to better illustrate the embodiments of the present invention and will not impose a limitation on the scope of the present invention unless otherwise required.

[0036] Refer to Figures 1 to 10 , in some embodiments, according to the silicone spraying process for preventing opto - electrical performance failure of an optocoupler of the present invention, which is applied to an optocoupler. The optocoupler includes a chip and bonding wires. One end of the bonding wire is connected to the chip, and its silicone spraying method at least includes the following steps:

[0037] S100: After obtaining the input signal of the chip welded with bonding wires;

[0038] S200: Spray an appropriate amount of liquid silicone onto the chip surface;

[0039] S300: Determine whether the glue - spraying process is qualified through optical vision detection; if not, stop the machine and give an alarm; if so, perform high - temperature curing to form an insulating layer, and then transport the sprayed chip to the output end.

[0040] In the present invention, silicone is sprayed on the chip after wire bonding. After the chip is wire-bonded and before chip pressing, a silicone spraying process is added, so that an insulating layer is formed on the chip surface. When the gold wire collapses, the bonding wire contacts the silicone insulating layer, which helps to prevent short-circuit leakage problems caused by the contact between the bonding wire and the chip, effectively avoid the failure of opto-coupling electrical performance caused by the collapse of the gold wire, and improve the yield and working stability of opto-couplers. The CCD automatic on-line detection method is adopted. Compared with the traditional quality detection method with low efficiency and uncontrollable accuracy, it can achieve full inspection of products and is conducive to ensuring production efficiency.

[0041] In some embodiments, a silicone spraying process is added after wire bonding in the method of the present invention, and then it is put into an oven for baking and high-temperature curing, so as to form a silicone insulating layer on the surface of the IR chip and / or PT chip, so that the collapsed gold wire cannot directly contact the chip, which helps to prevent the occurrence of short-circuit leakage phenomena.

[0042] In some embodiments, refer to Figure 5a , the method of the present invention uses a glue spraying machine with glue spraying and detection functions. The operation of the glue spraying machine is controlled by a computer to complete glue spraying, and a supporting CCD camera is used for automatic on-line visual detection to prevent missed spraying of products. Specifically, the chip to be sprayed is placed at the feeding end of the glue spraying machine, and the product to be sprayed is pushed into the preparatory position of the fixture track by a horizontally moving pusher plate, and the product is fixed by clamping with the fixture. Then, the glue spraying position and the stepping distance are determined according to the pre-programmed program, and the three-axis position is adjusted by the electric robotic arm of the glue spraying machine to align the glue spraying head with the established position (refer to Figure 5b ), and then the chip on the fixture is coated with glue through the glue spraying head. It should be noted that the glue spraying position and the stepping distance are determined by the program to achieve precise control of the spraying angle and spraying position, and the air pressure intensity is adjusted according to the detection data of the pressure sensor and the solenoid valve, and a high-density nozzle is used to achieve precise control of the silicone spraying amount, and then effectively control the thickness of the silicone insulating layer.

[0043] Among them, in some specific embodiments, the method of the present invention uses silicone with a viscosity of 4000 cps for spraying. The preheating temperature of the silicone is controlled between 4 °C and 6 °C, and the temperature of the glue spraying position is also controlled between 4 °C and 6 °C. The valve body temperature for starting the glue spraying head is controlled between 4 °C and 6 °C, and the air pressure of the cartridge connected to the glue spraying head is controlled between 70 KPa and 90 KPa. During the process of spraying silicone on a chip, the valve opening time of the glue spraying head each time is controlled between 1 ms and 1.2 ms, and the corresponding same-point pulse time is controlled between 0.9 ms and 1.1 ms. And the lifting time of the striker for detecting the distance between the glue spraying head and the chip is controlled between 0.5 ms and 0.7 ms, and the lifting height of the striker is controlled between 70% and 80%.

[0044] After the silicone spraying on the chip surface is completed, the product is conveyed by a conveyor belt to the CCD inspection area. The CCD lens is aligned with the inspection area, and the sprayed product is optically visually inspected step by step (see Figure 1 ), to detect whether the glue spraying is completed, whether there is missed spraying, and whether the height of the insulating layer does not meet the requirements. If the inspection fails, the silicone machine will alarm and stop working. If the inspection passes, the sprayed product is sent to an oven for baking and curing, and then the product covered with a silicone insulating layer is transported to the output end by a conveyor belt. After the whole set of automated silicone spraying is completed, the product is taken out, and the pressing of the IR chip and the PT chip is further completed.

[0045] It can be understood that in the glue spraying machine, the relative positions of the chip glue spraying position and the nozzle position of the glue spraying head are fixed. After the liquid silicone is ejected from the nozzle, it contacts the chip surface and slowly expands outward to wrap the chip working area. Then, after passing the inspection by the CCD camera, the chip coated with silicone is put into an oven and cured by baking at a high temperature of 150 °C for 2 hours, so that a silicone insulating layer is formed in the chip working area. Further, the present invention enables the ejected silicone to be evenly dispersed through a high-density mesh nozzle. It should be noted that since the high-density mesh nozzle filters the silicone into micron-level silicone, and the nozzle of the glue spraying machine does not spray directly against the bonding wire, during the spraying process, the impact force of its spraying has a negligible impact on the bonding wire, that is, the occurrence of gold wire collapse will not be caused by the spraying impact force.

[0046] The optocoupler of the present invention adopts the silicone spraying method of the above-mentioned embodiment of the present invention, and an insulating layer covers the surface of one side of the chip connected with the bonding wire. It can be understood that the chip can be an IR chip, a PT chip, etc. The optocoupler of the present invention sprays silicone on the surfaces of the IR chip and the PT chip and cures it into an insulating layer after the IR chip and the PT chip are connected with the bonding wire (i.e., the gold wire) and before the IR chip and the PT chip are pressed together. By adding the process of spraying the silicone insulating layer, the present invention makes the gold wire collapse have almost no impact on the operation of the IR chip and the PT chip, and solves the optocoupler electrical failure problem of chip short-circuit leakage caused by gold wire collapse from the source.

[0047] In some application embodiments, see Figure 1 and Figure 2 , the chip is a PT chip, the surface of the chip where the glue is sprayed is a conductive area, the materials of the base and emitter of the chip are aluminum, the size of the chip is 46 mils × 46 mils (which can also be 1.168 mm × 1.168 mm), and the size of the working area is 31 mils × 31 mils (which can also be 0.787 mm × 0.787 mm). See Figure 3 The collapse diagram of the optocoupler without sprayed silicone in Figure 4It is a figure of the wire collapse of an optocoupler after spraying silicone by the method of the present invention. It can be seen from the figure that for the optocoupler of the present invention, after the gold wire collapses, it only touches the insulating silicone layer and cannot form a short circuit with the surface of the chip, thus avoiding leakage contact.

[0048] The present invention conducts an actual test on the silicone spraying process for preventing optocoupler electrical performance failure. A glue spraying machine is used to spray silicone on the chip connected with bonding wires. Refer to Figure 6 the chip before glue spraying and Figure 7 the chip after glue spraying, and refer to Figure 8 the insulating layer height test figure. It can be seen that after silicone spraying, a silicone insulating layer with a thickness (i.e., height) of 0.07 mm to 0.08 mm is formed on the chip surface, so that after the gold wire collapses, it can only contact the insulating layer and cannot form a short circuit with the chip. Refer to Figure 9 the X-ray figure of wire collapse of the unsprayed optocoupler and Figure 10 the X-ray figure of wire collapse of the optocoupler after glue spraying. It can be seen from the figure that after the chip is sprayed with the insulating layer, the collapsed bonding wire can only touch the insulating layer and cannot touch the surface of the chip, thus effectively preventing the short circuit failure caused by the contact between the chip and the chip surface.

[0049] It should be recognized that the method steps in the embodiments of the present invention can be implemented or carried out by computer hardware, a combination of hardware and software, or computer instructions stored in a non-transitory computer-readable memory. The method can use standard programming techniques. Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system. However, if necessary, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language. In addition, for this purpose, the program can run on a dedicated integrated circuit programmed for this purpose.

[0050] In addition, the operations of the processes described herein can be performed in any suitable order, unless otherwise indicated herein or otherwise clearly contradicted by the context. The processes described herein (or variations and / or combinations thereof) can be executed under the control of one or more computer systems configured with executable instructions, and can be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) that are commonly executed on one or more processors, by hardware, or a combination thereof. The computer program includes multiple instructions executable by one or more processors.

[0051] Further, the method may be implemented in any type of computing platform operatively connected to a suitable one, including but not limited to personal computers, minicomputers, mainframes, workstations, network or distributed computing environments, separate or integrated computer platforms, or communicating with charged particle tools or other imaging devices, etc. Aspects of the present invention may be implemented in machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into the computing platform, such as a hard disk, optical read and / or write storage medium, RSM, ROM, etc., such that it is readable by a programmable computer and, when read by the storage medium or device, can be used to configure and operate the computer to perform the processes described herein. In addition, the machine-readable code, or portions thereof, may be transmitted via a wired or wireless network. When such media includes instructions or programs that implement the above-described steps in conjunction with a microprocessor or other data processor, the invention described herein includes these and other different types of non-transitory computer-readable storage media. When programmed according to the methods and techniques of the present invention, the present invention may also include the computer itself.

[0052] A computer program can be applied to input data to perform the functions described herein, thereby transforming the input data to generate output data stored in non-volatile memory. The output information can also be applied to one or more output devices such as a display. In a preferred embodiment of the present invention, the transformed data represents physical and tangible objects, including a specific visual depiction of the physical and tangible objects produced on the display.

[0053] As described above, only the preferred embodiments of the present invention are given, and the present invention is not limited to the above-described embodiments. As long as it achieves the technical effects of the present invention by the same means, any modifications, equivalent replacements, improvements, etc., made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. Within the scope of protection of the present invention, its technical solutions and / or embodiments may have various different modifications and variations.

Claims

1. A silicone spraying method, characterized in that: Applied to a photoelectric coupler, the photoelectric coupler comprises a chip and a bonding wire, one end of the bonding wire is connected to the chip, and the method comprises the following steps: S100, after obtaining an input signal of a chip welded with a bonding wire; wherein the chip includes an IR chip and a PT chip; S200, spraying a proper amount of liquid silicone with a viscosity of 4000cps on the surface of one side where the IR chip and the PT chip are connected with the bonding wire; wherein the preheating temperature of the silicone is controlled between 4 degrees Celsius and 6 degrees Celsius, and the temperature of the glue spraying position is controlled between 4 degrees Celsius and 6 degrees Celsius, so that the temperature of the valve body activated by the glue spraying head is controlled between 4 degrees Celsius and 6 degrees Celsius, and the air pressure of the barrel connected to the glue spraying head is controlled between 70KPa and 90KPa, and the valve opening time of each glue spraying head is controlled between 1ms and 1.2ms, and the corresponding same-point pulse time is controlled between 0.9ms and 1.1ms, so as to form a silicone insulation layer with a thickness of 0.07mm to 0.08mm on the chip surface; S300, determining whether the glue spraying process is qualified through optical visual inspection; if not, stopping the machine and giving an alarm; if so, performing high-temperature curing to form an insulating layer, and then transporting the sprayed chip to the output end; S400, pressing the IR chip and the PT chip both sprayed with an insulating layer.

2. The method according to claim 1, characterized in that In the step S300, baking is performed at 150 degrees Celsius for 2 hours to perform high temperature curing.

3. The method according to claim 1, characterized in that In the step S200, the air pressure is adjusted according to the detection data of the pressure sensor and the solenoid valve to control the amount of silicone spraying.

4. A silicone spraying control system, connected to a silicone machine, characterized in that: The system comprises: A computer device, wherein the computer device controls the silicone machine to execute the silicone spraying method according to any one of claims 1 to 3.

5. A photoelectric coupler manufactured by the silicone spraying method for a photoelectric coupler according to any one of claims 1 to 3.

6. The photoelectric coupler according to claim 5, characterized in that: A surface of the chip on one side connected with the bonding wire is covered with an insulating layer.

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