Device and method for preparing circuit board pin sheath

Abstract

The present invention discloses a circuit board pin sheath preparation device and method, the device includes a mounting plate, a plurality of pin sheath preparation units are installed on the mounting plate, the pin sheath preparation unit includes a unit housing, an inlet pipe, an electric four-way valve, a sheath liquid pipe, a pure water pipe, a gas pipe and an outlet pipe, the unit housing has a deposition cavity that can accommodate a chip and a circuit board pin connected to the chip, the deposition cavity is open at the lower end, one end of the inlet pipe is connected to one side of the deposition cavity, one end of the outlet pipe is connected to the other side of the deposition cavity, the other end of the inlet pipe is connected to one of the interfaces of the electric four-way valve, and the other three interfaces of the electric four-way valve are respectively connected to one end of the sheath liquid pipe, the pure water pipe and the gas pipe. The present invention prepares the circuit board pin sheath, which can effectively reduce the risk of short circuit between adjacent pins, prevent the circuit board pins from being corroded, effectively improve the pin seismic resistance, and at the same time has little effect on the heat dissipation of the circuit board, which is suitable for popularization and use.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor packaging, and in particular relates to a device and method for preparing a pin sheath of a circuit board. Background Art

[0002] A circuit board, also known as a printed circuit board (PCB), is an infrastructure used to connect and support electronic components. It is usually made of a conductive material (such as copper) combined with an insulating material (such as fiberglass or resin). The circuit board uses printing technology to transfer the circuit pattern to the substrate to achieve electrical connection and mechanical fixation of electronic components.

[0003] Circuit boards are widely used in various electronic devices, including computers, mobile phones, home appliances and industrial equipment. According to the complexity of the design, circuit boards can be divided into single-sided, double-sided and multi-layer boards. Modern circuit boards not only support basic line connections, but also can integrate large-scale integrated circuits (ICs) to meet the needs of high performance and miniaturization.

[0004] The pin of a circuit board is the connection part between an electronic component and a circuit board. It is usually a metal protrusion or soldering point, which is used to achieve electrical connection and mechanical stability. The function and design of the pin are crucial to the performance of the circuit board.

[0005] Various chips use more circuit board pins, such as microprocessors, digital signal processors, RAM, ROM, etc.

[0006] Most of the existing pins connecting chips to circuit boards are not packaged and protected. The pins are directly exposed, which will cause multiple problems:

[0007] 1. Short circuit risk: Exposed pins may cause short circuits due to accidental contact, which may lead to circuit failure or damage chips and other components. In particular, when the circuit board is used for a long time, tiny conductive paths are easily formed between the pins on the circuit board. This phenomenon is mainly caused by the migration of silver, which will form a short circuit between adjacent pins of the circuit board, causing equipment failure or failure.

[0008] 2. Corrosion problem: Moisture, oxygen or pollutants in the environment may cause corrosion on the pin surface and affect the electrical contact performance, which is particularly serious in humid or heavily polluted environments.

[0009] 3. Physical damage: Exposed pins are relatively fragile and can be easily vibrated during installation, transportation and use, causing physical damage such as bending or breaking.

[0010] At present, there are three methods for making protective layers on circuit boards: vapor deposition, liquid deposition, and artificial direct coating. The vapor deposition method is not suitable for the protective layer treatment of circuit board pins because it requires a high temperature environment and has a slow deposition speed. Artificial direct coating is difficult to control the coating thickness, and is prone to problems such as missing coating and bubbling. The coating thickness is very thick (usually greater than 2 mm), which makes it difficult for the circuit board to dissipate heat and affects the appearance of the circuit board, which is not practical. Liquid deposition methods generally include spin coating and dip coating. The spin coating method is to evenly drop the prepared PVA solution onto the center of the semiconductor substrate. By rotating the substrate at high speed, the PVA solution is diffused and evenly covers the entire surface of the moon. The desired film thickness is achieved by controlling the rotation speed and time, and the film thickness is usually between 200 nm and several microns. Dip coating is suitable for substrates with larger areas or more complex shapes. The method is to immerse the substrate in the PVA solution. Slowly remove the substrate and let it dry naturally. These two methods are also not suitable for the treatment of circuit board pin protective layers. The spatial structure of the circuit board pin structure is relatively complex, and the upper and lower surfaces of the pins must be coated with a protective layer. The spin coating method can only process smooth surface structures and cannot cope with the three-dimensional shape of circuit board pins. The dip coating method requires the entire circuit board to be immersed in the PVA solution, and cannot process specific areas of the circuit board pin position. Secondly, the dip coating method can only rely on natural drying and cannot control the thickness of the protective layer.

[0011] In summary, currently, there is no suitable device and method that can realize the sheath packaging of circuit board pins. In order to solve the above-mentioned short circuit risks, corrosion problems and physical damage, it is urgently needed to develop this. Summary of the invention

[0012] In order to solve the deficiencies of the prior art, the present invention provides a device and method for preparing a circuit board pin sheath.

[0013] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0014] A circuit board pin sheath preparation device comprises a mounting plate, on which a plurality of pin sheath preparation units are mounted, the pin sheath preparation units comprising a unit shell, an inlet pipe, an electric four-way valve, a sheath liquid pipe, a pure water pipe, a gas pipe and an outlet pipe, the unit shell having a deposition cavity capable of accommodating a chip and a circuit board pin connected to the chip, the deposition cavity having an opening at the lower end, one end of the inlet pipe connected to one side of the deposition cavity, one end of the outlet pipe connected to the other side of the deposition cavity, the other end of the inlet pipe connected to one of the interfaces of the electric four-way valve, the other three interfaces of the electric four-way valve connected to one end of the sheath liquid pipe, the pure water pipe and the gas pipe respectively, the sheath liquid pipe, the pure water pipe and the gas pipe are connected to the deposition cavity, and the deposition cavity is provided with a plurality of pins. The other end of the tube is respectively connected to a sheath liquid tank, a pure water tank and an air pump. A saturated aqueous solution of polyvinyl alcohol is stored in the sheath liquid tank, and deionized water is stored in the pure water tank. Liquid pumps are installed on both the sheath liquid tube and the pure water tube. The liquid pumps are used to pump the liquid in the sheath liquid tank or the pure water tank into the deposition cavity. A gas heater is installed on the gas tube. The gas heater is used to heat the gas in the gas tube. A semiconductor cooling plate is fixed on the unit shell. The semiconductor cooling plate is used to cool the deposition cavity. The electric four-way valve, the semiconductor cooling plate, the air pump and the liquid pump are all connected to the control unit. The control unit can control the opening and closing of the electric four-way valve, the air pump and the liquid pump, as well as the operation of the semiconductor cooling plate.

[0015] To optimize the above technical solutions, the specific measures taken also include:

[0016] A circuit board sealing gasket is arranged on the lower surface of the unit shell. When the pin shield preparation unit is pressed on the circuit board, the circuit board sealing gasket can be sealed with the circuit board to form a sealed space between the deposition cavity and the circuit board.

[0017] The deposition cavity is divided into an upper cavity and a lower cavity which are connected. A flexible sealing gasket is arranged in the upper cavity. The area of ​​the flexible sealing gasket is larger than the area of ​​the chip accommodated in the deposition cavity. When the pin protection layer preparation unit is pressed on the circuit board, the upper surface of the chip is completely in contact with the flexible sealing gasket. The pin of the circuit board is located in the lower cavity.

[0018] The circuit board pin sheath preparation device includes an equipment frame, which includes a bottom horizontal frame and a top fixed frame. The top fixed frame is located above the bottom horizontal frame. A telescopic motor is fixedly installed on the top fixed frame. The telescopic shaft of the telescopic motor is fixedly connected to the mounting plate. The telescopic motor can drive the mounting plate to move up and down. The telescopic motor is connected to a control unit, and the control unit can control the operation of the telescopic motor.

[0019] The bottom horizontal frame is provided with a slide rail, a circuit board positioning frame, a telescopic cylinder, a front in-position sensor and a rear in-position sensor. The circuit board positioning frame is slidably installed on the slide rail, the circuit board can be installed on the circuit board positioning frame for positioning, the telescopic cylinder is fixedly installed on the bottom horizontal frame, the cylinder shaft of the telescopic cylinder is connected to the circuit board positioning frame, the telescopic cylinder can push the circuit board positioning frame to slide along the slide rail, the front in-position sensor and the rear in-position sensor are respectively installed at the front end and the rear end of the slide rail, the front in-position sensor and the rear in-position sensor are connected with the telescopic cylinder signal, the front in-position sensor and the rear in-position sensor are used to control the telescopic cylinder to stop operating, the telescopic cylinder is connected with the control unit signal, the control unit can control the operation of the telescopic cylinder, when the circuit board positioning frame moves to the rear end of the slide rail, the chip on the circuit board and the circuit board pins connected to the chip are just located below the corresponding pin sheath preparation unit.

[0020] A liquid heater and a thermocouple are provided in the sheath liquid tank. The liquid heater is used to heat and keep warm the saturated aqueous solution of polyvinyl alcohol in the sheath liquid tank. The thermocouple is used to monitor the temperature of the saturated aqueous solution of polyvinyl alcohol. Both the liquid heater and the thermocouple are connected to a control unit. The control unit can receive the temperature information of the thermocouple and control the operation of the liquid heater.

[0021] The other end of the outlet pipe is connected to a waste bin.

[0022] The inner surfaces of the sheath liquid pipe, the deposition cavity and the outlet pipe are all coated with polytetrafluoroethylene coating or silicone oil or silane coating.

[0023] A method for preparing a circuit board pin sheath, using the above-mentioned circuit board pin sheath preparation device, the specific method comprises the following steps:

[0024] Step 1: pre-fabricate a pin sheath preparation unit according to the distribution and size of the chip and pins on the circuit board, and install the pin sheath preparation unit on the mounting board;

[0025] Step 2: Place the circuit board on the circuit board positioning frame, the control unit controls the telescopic cylinder to move the circuit board positioning frame to the rear end of the slide rail, and the control unit controls the telescopic motor to move the mounting plate downward, so that the pin sheath preparation unit is pressed just on the circuit board, the chip and the circuit board pins are both located in the deposition cavity, the circuit board sealing gasket is sealed with the circuit board, and the flexible sealing gasket seals the upper surface of the chip;

[0026] Step 3: The control unit controls the deionized water in the pure water tank to be pumped into the deposition cavity through the pure water pipe and then flows out through the outlet pipe. During this process, the deionized water cleans the chip side, circuit board pins and circuit board between the pins in the deposition cavity.

[0027] Step 4: The control unit stops pumping water from the pure water tank, and controls the saturated aqueous solution of polyvinyl alcohol in the protective layer liquid tank to be continuously and continuously pumped into the deposition cavity, and then flows out through the outlet pipe. At the same time, the semiconductor hot and cold plate is started to cool the deposition cavity. The saturated aqueous solution of polyvinyl alcohol is evenly cooled in the deposition cavity, resulting in a decrease in the solubility of the saturated aqueous solution of polyvinyl alcohol, and polyvinyl alcohol is precipitated. It is deposited on the side of the chip, the pins of the circuit board, and the circuit board between the pins to form a thin film, which gradually thickens over time.

[0028] Step 5. After a predetermined time, the control unit stops the protective layer liquid tank pumping the saturated aqueous solution of polyvinyl alcohol, turns off the semiconductor hot and cold plate, and instead controls the air pump to pump air into the deposition cavity through the gas pipe. At the same time, the gas heater is started to heat the air. The air squeezes out the saturated aqueous solution of polyvinyl alcohol remaining in the deposition cavity from the outlet pipe, and the deposition cavity retains a film deposited on the side of the chip, the pins of the circuit board, and the circuit board between the pins, as well as the residual solution of polyvinyl alcohol attached to the film. The film and the residual solution of polyvinyl alcohol are dried by air to form a hard insulating circuit board pin protective layer on the side of the chip, the pins of the circuit board, and the circuit board between the pins.

[0029] In step 4, the polyvinyl alcohol used in the saturated aqueous solution of polyvinyl alcohol is low molecular weight polyvinyl alcohol, the semiconductor hot and cold plate has a cooling gradient of 10°C-20°C for the saturated aqueous solution of polyvinyl alcohol in the deposition cavity, the flow rate of the saturated aqueous solution of polyvinyl alcohol in the deposition cavity is not more than 2mm / s, and the thickness of the film formed by the deposition of polyvinyl alcohol is between 200μm-500μm.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention sets a pin protection layer preparation unit, sets a deposition cavity for the chip and the circuit board pins connected to the chip, and deposits the circuit board pins in the deposition cavity, so that the range of the circuit board pin protection layer is limited to the periphery of the circuit board pins, ensuring that the protection layer is in a predetermined position.

[0032] 2. The present invention provides a new method for preparing a circuit board pin protective layer. Deionized water is first introduced into the deposition cavity to clean the circuit board pins, and then a relatively high temperature saturated aqueous solution of polyvinyl alcohol is introduced to precipitate the polyvinyl alcohol by cooling the temperature and deposit it on the side of the chip, the circuit board pins and the circuit board between the pins. When the thickness of the deposited film reaches a predetermined range, high-temperature dry air is introduced to dry and harden the polyvinyl alcohol film to form a hard insulating circuit board pin protective layer. This method can quickly deposit a polyvinyl alcohol film at the circuit board pins with high efficiency, and the thickness can be controlled by the concentration of the input saturated aqueous solution of polyvinyl alcohol, the deposition time, the cooling gradient, etc., thereby preparing a circuit board pin protective layer with a predetermined thickness and no bubble doping at a predetermined position of the circuit board pin.

[0033] 3. The pins of the circuit board have an S-shaped structure, in which the middle has an upper and lower surface. When the saturated aqueous solution of polyvinyl alcohol is not flowing and deposited, the polyvinyl alcohol will fall after precipitation, resulting in more polyvinyl alcohol deposition on the upper surface of the circuit board pins and less polyvinyl alcohol deposition on the lower surface of the circuit board pins. The circuit board between the circuit board pins can obtain the most deposits, which leads to uneven deposition of the circuit board pin sheath. To alleviate this situation, the method adopted in the present invention is that during the deposition process, the saturated aqueous solution of polyvinyl alcohol continuously and coherently flows through the deposition cavity, so that the upper surface, lower surface and circuit board of the circuit board pin are in more uniform contact with the water flow, thereby making the upper surface, lower surface and circuit board of the circuit board pin obtain more uniform polyvinyl alcohol deposition, which effectively alleviates the problem of uneven deposition of the circuit board pins.

[0034] 4. The present invention prepares the circuit board pin protection layer, which can effectively reduce the risk of short circuit between adjacent pins, prevent the circuit board pins from being corroded, effectively improve the pin's anti-vibration ability, and at the same time has little effect on the heat dissipation of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the circuit board;

[0036] Figure 2 It is a structural schematic diagram of a circuit board pin sheath preparation device of the present invention;

[0037] Figure 3 It is a top view of the bottom horizontal shelf;

[0038] Figure 4 It is a schematic diagram of the internal structure of the pin sheath preparation unit;

[0039] Figure 5 It is a schematic diagram of the pin sheath preparation unit being pressed onto the circuit board;

[0040] Figure 6 It is a top view of the pin sheath preparation unit;

[0041] Figure 7 It is a schematic diagram of positioning a circuit board on a circuit board positioning frame;

[0042] Figure 8 yes Figure 7 A top view of the middle and bottom horizontal racks;

[0043] Fig. 9 It is a schematic diagram of the circuit board being sent to the pin sheath preparation unit just below;

[0044] Fig.10 yes Fig. 9 A top view of the middle and bottom horizontal racks;

[0045] Fig.11 It is a schematic diagram of a circuit board pin cover preparation device when a pin cover preparation unit moves downward and presses on a circuit board.

[0046] The accompanying drawings are marked as follows: mounting plate 1, pin sheath preparation unit 2, deposition inner cavity 2a, upper cavity 2b, lower cavity 2c, unit shell 21, semiconductor hot and cold plate 21a, inlet pipe 22, electric four-way valve 23, sheath liquid pipe 24, sheath liquid tank 24a, pure water pipe 25, pure water tank 25a, gas pipe 26, air pump 26a, outlet pipe 27, waste bin 27a, circuit board sealing gasket 28, flexible sealing gasket 29, circuit board 3, chip 31, circuit board pin 32, equipment frame 4, bottom horizontal frame 41, top fixed frame 42, telescopic motor 43, slide rail 44, circuit board positioning frame 45, telescopic cylinder 46, front in-position sensor 47, rear in-position sensor 48, control unit 5. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0048] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0049] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0050] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation and may indicate the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include unlisted steps or units, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0051] like Figure 1 As shown, this is a circuit board 3 used for depositing a protective layer in this embodiment. On the circuit board 3, there are circuit board pins 32 of two chips 31 that need to deposit a protective layer. Therefore, in this embodiment, two corresponding pin protective layer preparation units 2 are manufactured according to the positions and sizes of the chips 31 and circuit board pins 32 on the circuit board 3, and are installed on the mounting plate 1, and then the mounting plate 1 is installed on the equipment frame 4.

[0052] like Figure 2 and 3 As shown, the equipment frame 4 includes two main parts: a bottom horizontal frame 41 and a top fixed frame 42. The top fixed frame 42 includes a telescopic motor 43, and the bottom horizontal frame 41 includes a slide rail 44, a circuit board positioning frame 45, a telescopic cylinder 46, a front in-position sensor 47, and a rear in-position sensor 48.

[0053] The equipment frame 4 is made of stainless steel and is divided into two parts, the left half of which only has the left half of the bottom horizontal frame 41, and the right half of which has the top fixed frame 42 and the right half of the bottom horizontal frame 41.

[0054] The telescopic motor 43 is fixed on the top fixing frame 42, and the telescopic shaft of the telescopic motor 43 is fixedly connected to the mounting plate 1. When the telescopic shaft is extended downward, the mounting plate 1 and the two lead sheath preparation units 2 are lowered together. The sheath liquid tank 24a, the pure water tank 25a, and the air pump 26a are all installed on the top fixing frame 42.

[0055] There are two slide rails 44. The circuit board positioning frame 45 is mounted on the slide rails 44 and can slide along the slide rails 44. The circuit board positioning frame 45 is made of stainless steel. The four corners of the circuit board positioning frame 45 are provided with alignment protrusions, which just correspond to the four corners of the circuit board 3. The ground of the circuit board positioning frame 45 is hollowed out. When the circuit board 3 is placed on the circuit board positioning frame 45, it is just completely stuck and cannot shake. The telescopic cylinder 46 is installed at the left end of the bottom horizontal frame 41, located below the circuit board positioning frame 45. The cylinder shaft of the telescopic cylinder 46 is connected to the circuit board positioning frame 45 through a slider. The telescopic cylinder 46 can push the circuit board positioning frame 45 to slide along the slide rail 44. The front in-position sensor 47 and the rear in-position sensor 48 are respectively installed at the front end and the rear end of the slide rail 44, which are used to limit the stroke of the circuit board positioning frame 45. Once the circuit board positioning frame 45 touches the front in-position sensor 47 and the rear in-position sensor 48, it will stop moving.

[0056] When the circuit board positioning frame 45 moves to the rear end of its own travel, that is, the rightmost end, it is just located below the mounting plate 1, and the telescopic motor 43 drives the mounting plate 1 and the two pin sheath preparation units 2 to descend together, so that the two pin sheath preparation units 2 are respectively covered on the two chips 31 and their circuit board pins 32. Figure 5 shown.

[0057] The structure of the pin sheath preparation unit 2 is as follows Figure 4As shown, it includes a unit shell 21, an inlet pipe 22, an electric four-way valve 23, a sheathing liquid pipe 24, a pure water pipe 25, a gas pipe 26, an outlet pipe 27, a circuit board sealing gasket 28 and a flexible sealing gasket 29. The unit shell 21 has a deposition cavity 2a that can accommodate a chip 31 and a circuit board pin 32 connected to the chip 31. The lower end of the deposition cavity 2a is open, one end of the inlet pipe 22 is connected to one side of the deposition cavity 2a, one end of the outlet pipe 27 is connected to the other side of the deposition cavity 2a, the other end of the inlet pipe 22 is connected to one of the interfaces of the electric four-way valve 23, and the other three interfaces of the electric four-way valve 23 are respectively connected to one end of the sheathing liquid pipe 24, the pure water pipe 25 and the gas pipe 26. The other ends of the tube 25 and the gas tube 26 are connected to the sheath liquid tank 24a, the pure water tank 25a and the air pump 26a respectively. The sheath liquid tank 24a contains a saturated aqueous solution of polyvinyl alcohol. The sheath liquid tank 24a is also provided with a liquid heater and a thermocouple. The liquid heater is used to heat and keep the saturated aqueous solution of polyvinyl alcohol in the sheath liquid tank 24a warm. Specifically, the heating temperature of the saturated aqueous solution of polyvinyl alcohol is 60°C, and the concentration of the saturated aqueous solution of polyvinyl alcohol is 20%-25% (weight ratio). The thermocouple is used to monitor the temperature of the saturated aqueous solution of polyvinyl alcohol. The liquid heater and the thermocouple are connected to the control unit 5, and the control unit 5 can receive the temperature information of the thermocouple and control the operation of the liquid heater. The saturated aqueous solution of polyvinyl alcohol needs to be sealed and stored, so the sheath liquid tank 24a is a sealed box. Deionized water is stored in the pure water tank 25a. Liquid pumps are installed on the sheath liquid pipe 24 and the pure water pipe 25. A gas heater is installed on the gas pipe 26. The gas heater is used to heat the gas in the gas pipe 26. The heating temperature of the gas heater is 50-60°C. A semiconductor cooling plate 21a is fixed on the unit shell 21. The semiconductor cooling plate 21a is used to cool the deposition cavity 2a. Figure 6 It can be seen that the semiconductor cooling and heating plate 21a extends from the left side to the right side of the unit housing 21. The semiconductor cooling and heating plate 21a is used to uniformly reduce the temperature from the front to the back of the deposition cavity 2a. The temperature reduction gradient is 10°C-20°C, depending on the thickness of the protective layer to be deposited. The electric four-way valve 23, the semiconductor cooling and heating plate 21a, the air pump 26a and the liquid pump are all connected to the control unit 5. The control unit 5 can control the opening and closing of the electric four-way valve 23, the air pump 26a and the liquid pump and the operation of the semiconductor cooling and heating plate 21a.

[0058] from Figure 5 It can be seen that when the circuit board sealing pad 28 is pressed on the circuit board 3, it can be sealed with the circuit board 3 to prevent the liquid and gas in the deposition cavity 2a from leaking out, and the flexible sealing pad 29 can be completely sealed with the upper surface of the chip 31 to prevent the liquid and gas from moving to the upper surface of the chip 31. By providing the circuit board sealing pad 28 and the flexible sealing pad 29, it is ensured that deposition occurs only in a small area where the circuit board pins 32 are located.

[0059] The inner surfaces of the sheath liquid pipe 24, the deposition cavity 2a and the outlet pipe 27 are all coated with polytetrafluoroethylene coating. In other embodiments, silicone oil or silane coating can also be selected. The coating is used to prevent polyvinyl alcohol from being deposited on the wall of the sheath liquid pipe, the wall of the deposition cavity and the wall of the outlet pipe, thereby blocking the pipe or cavity.

[0060] The control unit 5 uses PLC.

[0061] The polyvinyl alcohol in the saturated aqueous solution of polyvinyl alcohol is selected to be a low molecular weight polyvinyl alcohol having a molecular weight between 10,000 and 30,000.

[0062] The following is an explanation of the specific method for preparing the circuit board pin sheath of the present invention:

[0063] Step 1. Predetermine the thickness of the circuit board pin sheath to be deposited, and conduct a deposition time experiment. The experimental method is: preselect several circuit boards 3 as experimental circuit boards, and perform steps 2-6. Except for the predetermined deposition time in step 5, each circuit board 3 is the same, so as to obtain multiple circuit board test pieces with different circuit board pin sheath thicknesses. Select the circuit board test piece with the closest thickness to the predetermined circuit board pin sheath thickness, and use its deposition time as the deposition time of all circuit boards 3. Generally speaking, the thickness of the film formed by the deposition of polyvinyl alcohol is preferably between 200μm and 500μm. At this time, the film thickness can not only improve the anti-seismic ability of the circuit board pins and ensure the insulation between the pins, but also have little effect on the heat dissipation of the circuit board.

[0064] Step 2: Install the circuit board 3: Figure 7-8 As shown, the circuit board 3 is placed on the circuit board positioning frame 45, as shown in FIG. Figure 9-10 As shown, the control unit 5 controls the telescopic cylinder 46 to move the circuit board positioning frame 45 to the rear end of the slide rail 44, as shown in FIG. Fig.11 As shown, the control unit 5 controls the telescopic motor 43 to move the mounting plate 1 downward, so that the pin sheath preparation unit 2 is pressed just on the circuit board 3, the chip 31 and the circuit board pin 32 are both located in the deposition cavity 2a, the circuit board sealing gasket 28 is sealed with the circuit board 3, and the flexible sealing gasket 29 seals the upper surface of the chip 31. At this time, the state is as follows Figure 5 As shown;

[0065] Step 3, the control unit 5 controls the deionized water in the pure water tank 25a to be pumped into the deposition cavity 2a through the pure water pipe 25, and then flows out through the outlet pipe 27. In this process, the deionized water cleans the side of the chip 31, the circuit board pins 32 and the circuit board between the pins in the deposition cavity 2a;

[0066] Step 4, the control unit 5 stops the pure water tank 25a from pumping water, and controls the saturated aqueous solution of polyvinyl alcohol in the protective layer liquid tank 24a to be pumped into the deposition cavity 2a. The temperature of the saturated aqueous solution of polyvinyl alcohol is 60°C, and the flow rate of the saturated aqueous solution into the deposition cavity 2a is 1.5 mm / s. At the same time, the semiconductor hot and cold plate 21a is started to cool the deposition cavity 2a, and the temperature reduction gradient is 20°C. The saturated aqueous solution of polyvinyl alcohol is evenly cooled in the deposition cavity 2a, resulting in a decrease in the solubility of the saturated aqueous solution of polyvinyl alcohol, and polyvinyl alcohol is precipitated. It is deposited on the side of the chip 31, the circuit board pins 32, and the circuit board between the pins to form a thin film, which gradually thickens over time;

[0067] Step 5. After the predetermined deposition time, the control unit 5 stops the protective layer liquid tank 24a from pumping the saturated aqueous solution of polyvinyl alcohol, closes the semiconductor cooling and heating plate 21a, and controls the air pump 26a to pump air into the deposition cavity 2a through the gas pipe 26. At the same time, the gas heater is started to heat the air. The air temperature is 60°C. The air squeezes out the saturated aqueous solution of polyvinyl alcohol remaining in the deposition cavity 2a from the outlet pipe 27. The deposition cavity 2a retains a film deposited on the side of the chip 31, the circuit board pins 32, and the circuit board between the pins, as well as the residual solution of polyvinyl alcohol attached to the film. The film and the residual solution of polyvinyl alcohol are dried by air, so that a hard insulating circuit board pin protective layer is formed on the side of the chip 31, the circuit board pins 32, and the circuit board between the pins.

[0068] Step 6, the control unit 5 stops the air pump 26a and turns off the gas heater, controls the telescopic motor 43 to move the mounting plate 1 upward, and then controls the telescopic cylinder 46 to move the circuit board positioning frame 45 to the front end of the slide rail 44, and the staff removes the circuit board 3 with the circuit board pin protective layer.

[0069] The above are preferred embodiments of the present application, but those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0070] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A circuit board pin sheath preparation device, comprising a mounting plate (1), characterized in that: A plurality of pin sheath preparation units (2) are installed on the mounting plate (1), the pin sheath preparation units (2) comprising a unit housing (21), an inlet pipe (22), an electric four-way valve (23), a sheath liquid pipe (24), a pure water pipe (25), a gas pipe (26) and an outlet pipe (27), the unit housing (21) having a deposition cavity (2a) capable of accommodating a chip (31) and a circuit board pin (32) connected to the chip (31), the lower end of the deposition cavity (2a) being open The inlet pipe (22) has one end connected to one side of the deposition cavity (2a), the outlet pipe (27) has one end connected to the other side of the deposition cavity (2a), the inlet pipe (22) has the other end connected to one of the interfaces of the electric four-way valve (23), the other three interfaces of the electric four-way valve (23) are respectively connected to one end of the protective layer liquid pipe (24), the pure water pipe (25) and the gas pipe (26), the other ends of the protective layer liquid pipe (24), the pure water pipe (25) and the gas pipe (26) are respectively connected to the protective layer liquid tank ( 24a), a pure water tank (25a) and an air pump (26a), wherein the protective layer liquid tank (24a) stores a saturated aqueous solution of polyvinyl alcohol, and the pure water tank (25a) stores deionized water. The protective layer liquid pipe (24) and the pure water pipe (25) are both equipped with a liquid pump, and the liquid pump is used to pump the liquid in the protective layer liquid tank (24a) or the pure water tank (25a) into the deposition cavity (2a). The gas pipe (26) is equipped with a gas heater, and the gas heater is used to heat the gas. The gas in the body tube (26) is heated, a semiconductor heat and cold plate (21a) is fixedly attached to the unit shell (21), and the semiconductor heat and cold plate (21a) is used to cool the deposition cavity (2a). The electric four-way valve (23), the semiconductor heat and cold plate (21a), the air pump (26a) and the liquid pump are all connected to the control unit (5), and the control unit (5) can control the opening and closing of the electric four-way valve (23), the air pump (26a) and the liquid pump, as well as the operation of the semiconductor heat and cold plate (21a).

2. A circuit board pin sheath preparation device according to claim 1, characterized in that: A circuit board sealing gasket (28) is provided on the lower surface of the unit housing (21); when the pin shield preparation unit (2) is pressed onto the circuit board (3), the circuit board sealing gasket (28) can be sealed and matched with the circuit board (3), so that a sealed space is formed between the deposition cavity (2a) and the circuit board (3).

3. A circuit board pin sheath preparation device according to claim 2, characterized in that: The deposition inner cavity (2a) is divided into an upper cavity (2b) and a lower cavity (2c) which are connected. A flexible sealing pad (29) is arranged in the upper cavity (2b). The area of ​​the flexible sealing pad (29) is larger than the area of ​​the chip (31) accommodated in the deposition inner cavity (2a). When the pin protection layer preparation unit (2) is pressed on the circuit board (3), the upper surface of the chip (31) is completely in contact with the flexible sealing pad (29). The circuit board pin (32) is located in the lower cavity (2c).

4. A circuit board pin sheath preparation device according to claim 3, characterized in that: The invention comprises an equipment frame (4), wherein the equipment frame (4) comprises a bottom horizontal frame (41) and a top fixed frame (42), wherein the top fixed frame (42) is located above the bottom horizontal frame (41), and a telescopic motor (43) is fixedly mounted on the top fixed frame (42), wherein the telescopic shaft of the telescopic motor (43) is fixedly connected to a mounting plate (1), wherein the telescopic motor (43) can drive the mounting plate (1) to move up and down, and wherein the telescopic motor (43) is connected to a control unit (5), and wherein the control unit (5) can control the operation of the telescopic motor (43).

5. A circuit board pin sheath preparation device according to claim 4, characterized in that: The bottom horizontal frame (41) is provided with a slide rail (44), a circuit board positioning frame (45), a telescopic cylinder (46), a front arrival sensor (47) and a rear arrival sensor (48); the circuit board positioning frame (45) is slidably mounted on the slide rail (44); the circuit board (3) can be mounted on the circuit board positioning frame (45) for positioning; the telescopic cylinder (46) is fixedly mounted on the bottom horizontal frame (41); the cylinder shaft of the telescopic cylinder (46) is connected to the circuit board positioning frame (45); the telescopic cylinder (46) can push the circuit board positioning frame (45) to slide along the slide rail (44); the front arrival sensor (47) and the rear arrival sensor (48) They are respectively installed at the front end and the rear end of the slide rail (44); the front arrival sensor (47) and the rear arrival sensor (48) are connected to the telescopic cylinder (46) by signal; the front arrival sensor (47) and the rear arrival sensor (48) are used to control the telescopic cylinder (46) to stop operating; the telescopic cylinder (46) is connected to the control unit (5) by signal; the control unit (5) can control the telescopic cylinder (46) to operate; when the circuit board positioning frame (45) moves to the rear end of the slide rail (44), the chip (31) on the circuit board (3) and the circuit board pin (32) connected to the chip (31) are exactly located below the corresponding pin shield preparation unit (2).

6. A circuit board pin sheath preparation device according to claim 5, characterized in that: The sheath liquid tank (24a) is provided with a liquid heater and a thermocouple. The liquid heater is used to heat and keep warm the saturated aqueous solution of polyvinyl alcohol in the sheath liquid tank (24a). The thermocouple is used to monitor the temperature of the saturated aqueous solution of polyvinyl alcohol. The liquid heater and the thermocouple are both connected to a control unit (5). The control unit (5) can receive the temperature information of the thermocouple and control the operation of the liquid heater.

7. A circuit board pin sheath preparation device according to claim 1, characterized in that: The other end of the outlet pipe (27) is connected to a waste discharge barrel (27a).

8. The circuit board pin sheath preparation device according to claim 1, characterized in that: The inner surfaces of the sheath liquid pipe (24), the deposition cavity (2a) and the outlet pipe (27) are all coated with a polytetrafluoroethylene coating or a silicone oil or a silane coating.

9. A method for preparing a circuit board pin sheath, characterized in that: The circuit board pin sheath preparation device according to claim 6 is used, and the specific method comprises the following steps: Step 1: prefabricate a pin sheath preparation unit (2) according to the distribution and size of the chip (31) and the circuit board pins (32) on the circuit board (3), and install the pin sheath preparation unit (2) on the mounting plate (1); Step 2: placing the circuit board (3) on the circuit board positioning frame (45), the control unit (5) controls the telescopic cylinder (46) to move the circuit board positioning frame (45) to the rear end of the slide rail (44), and the control unit (5) controls the telescopic motor (43) to move the mounting plate (1) downward, so that the pin protection layer preparation unit (2) is pressed exactly on the circuit board (3), the chip (31) and the circuit board pin (32) are both located in the deposition cavity (2a), the circuit board sealing gasket (28) is sealed with the circuit board (3), and the flexible sealing gasket (29) seals the upper surface of the chip (31); Step 3, the control unit (5) controls the deionized water in the pure water tank (25a) to be pumped into the deposition cavity (2a) through the pure water pipe (25), and then flows out through the outlet pipe (27). During this process, the deionized water cleans the side of the chip (31), the circuit board pins (32) and the circuit board between the pins in the deposition cavity (2a); Step 4, the control unit (5) stops the pure water tank (25a) from pumping water, and instead controls the saturated aqueous solution of polyvinyl alcohol in the protective layer liquid tank (24a) to be continuously and continuously pumped into the deposition cavity (2a), and then flows out through the outlet pipe (27), and at the same time the semiconductor hot and cold plate (21a) is started to cool the deposition cavity (2a), and the saturated aqueous solution of polyvinyl alcohol is uniformly cooled in the deposition cavity (2a), resulting in a decrease in the solubility of the saturated aqueous solution of polyvinyl alcohol, and polyvinyl alcohol is precipitated, and deposited on the side of the chip (31), the circuit board pins (32), and the circuit board between the pins to form a thin film, which gradually thickens over time; Step 5. After a predetermined time has passed, the control unit (5) stops the protective layer liquid tank (24a) from pumping the saturated aqueous solution of polyvinyl alcohol, closes the semiconductor cooling plate (21a), and controls the air pump (26a) to pump air into the deposition cavity (2a) through the gas pipe (26). At the same time, the gas heater is started to heat the air. The air squeezes out the saturated aqueous solution of polyvinyl alcohol remaining in the deposition cavity (2a) from the outlet pipe (27). The deposition cavity (2a) retains a film deposited on the side of the chip (31), the circuit board pins (32), and the circuit board between the pins, as well as the residual polyvinyl alcohol solution attached to the film. The film and the residual polyvinyl alcohol solution are dried by air, so that the side of the chip (31), the circuit board pins (32), and the circuit board between the pins form a hard insulating circuit board pin protective layer.

10. A method for preparing a circuit board pin sheath according to claim 9, characterized in that: In step 4, the polyvinyl alcohol used in the saturated aqueous solution of polyvinyl alcohol is low molecular weight polyvinyl alcohol, the semiconductor hot and cold plate (21a) cools the saturated aqueous solution of polyvinyl alcohol in the deposition cavity (2a) at a temperature gradient of 10°C-20°C, the flow rate of the saturated aqueous solution of polyvinyl alcohol in the deposition cavity (2a) is not greater than 2 mm / s, and the thickness of the film formed by the deposition of polyvinyl alcohol is between 200 μm and 500 μm.

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