A glue-point positioning welding process in NTC welding

Abstract

The invention relates to a glue-dispensing positioning welding process in NTC welding, comprising the following steps: dispensing glue at a position where a module substrate connects a welding plate and an NTC thermistor; detecting whether the position of the glue liquid is accurate, detecting whether the diameter of the glue liquid meets the requirements, and if both meet the requirements, entering the next step; sequentially attaching the welding plate and the NTC thermistor to the surface of the module substrate; vacuum welding the module substrate, the welding plate and the NTC thermistor; preheating the module substrate, the welding plate and the NTC thermistor, and reducing oxides on the module substrate, the welding plate and the NTC thermistor in a formic acid environment; vacuum welding, volatilizing the glue liquid between the module substrate, the welding plate and the NTC thermistor during welding, and no NTC positioning tooling is required to be set in the packaging process through the above process, and there is no NTC damage caused by disassembling the tooling.

Description

Technical Field

[0001] The invention belongs to the technical field of NTC welding, and in particular relates to a glue spot positioning welding process in NTC welding. Background Art

[0002] At present, with the rapid development of new energy technology, the demand for power semiconductors is strong. At present, in the field of new energy vehicles, HPD packages are of two types: IGBT and SIC, which integrate temperature monitoring elements - NTC resistors. Since NTC is fired at high temperature, it has an irregular "drum" shape after molding. In the power module packaging process, if NTC is directly mounted on the module substrate, it will roll. In order to prevent mounting, turnover, and welding deviation, it is necessary to take measures to position NTC.

[0003] Traditional NTC positioning methods include solder paste positioning and solder piece processing positioning. Solder paste positioning requires cleaning flux, which is expensive and requires consideration of production environment compliance. Solder piece processing positioning increases the difficulty of NTC mounting, and when the positioning tooling is disassembled after welding, the NTC is often damaged, resulting in a decrease in module packaging yield. In view of this, this solution was created. Summary of the invention

[0004] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a glue spot positioning welding process in NTC welding, which can achieve patch positioning between the module substrate and the welding piece and the NTC thermistor by glue spotting.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a glue spot positioning welding process in NTC welding, comprising the following steps:

[0006] S1. Dispense glue at the location where the module substrate connects the welding plate and the NTC thermistor;

[0007] S2, check whether the position of the glue is accurate, check whether the diameter of the glue is in compliance, if both are in compliance, proceed to the next step;

[0008] S3, attach the welding plate and the NTC thermistor to the surface of the module substrate in sequence;

[0009] S4, vacuum welding the module substrate, welding plate and NTC thermistor;

[0010] S41, preheating the module substrate, the welding plate and the NTC thermistor, and reducing the oxides on the module substrate, the welding plate and the NTC thermistor in a formic acid environment;

[0011] S42, perform vacuum welding, and volatilize the glue between the module substrate, the welding plate and the NTC thermistor during welding.

[0012] Furthermore, in step S41, the preheating temperature is between 190°C and 210°C.

[0013] Further, the specific steps of step S41 are as follows: evacuate to a vacuum degree below 1 mbar, fill with nitrogen until the vacuum degree reaches 940-960 mbar, heat to 200°C, maintain the temperature for 20-40s, evacuate to 1 mbar, fill with formic acid until the vacuum degree reaches 840-860 mbar, and maintain in a 200°C formic acid environment for 140-160s.

[0014] Furthermore, the flow rate during nitrogen filling is 60-100 L / min.

[0015] Furthermore, the flow rate during formic acid charging is 30 L / min.

[0016] Furthermore, the welding temperature in step S42 is 250°C-270°C.

[0017] Further, the specific steps of step S42 are as follows: heating to the welding temperature of 260°C, maintaining for 30-40 seconds after reaching the target temperature, evacuating to a vacuum degree of 1 mbar, maintaining for 60-70 seconds after reaching the vacuum degree, and filling with nitrogen to a vacuum degree of 1000 mbar.

[0018] Furthermore, the step S4 also includes a step S43; Step 43, cooling the finished product.

[0019] Furthermore, the cooling temperature in step S43 is 40°C-50°C.

[0020] Furthermore, the glue liquid is an adhesive, and the adhesive has a complete volatilization temperature of 250°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention dispenses glue on the surface corresponding to the position where the module substrate is connected to the connecting welding plate and the NTC thermistor, and then sequentially attaches the welding plate and the NTC thermistor to the position. Since the glue is viscous, it can avoid offset or rolling during mounting, turnover and welding. The packaging process does not require NTC positioning tooling, and the glue will completely evaporate during the vacuum welding process. There is no need to disassemble the tooling after welding, and there is no situation where the NTC is damaged due to disassembly of the tooling. In addition, the glue positioning welding process provided by this solution is cheaper and has lower mounting difficulty than the existing solder paste positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A pressure and temperature curve diagram of a glue spot positioning welding process in NTC welding of the present invention;

[0024] Figure 2 It is a three-dimensional structural schematic diagram of an NTC welding dispensing positioning device of the present invention;

[0025] Figure 3 It is a schematic diagram of the three-dimensional structure of the glue dispensing component in the present invention;

[0026] Figure 4 It is a partially enlarged three-dimensional structural schematic diagram of the first mounting frame and the dispensing body in the present invention;

[0027] Figure 5 Schematic diagram of the three-dimensional structure of the dot colloid in the present invention;

[0028] Figure 6 It is a schematic diagram of the three-dimensional structure of the patch component in the present invention;

[0029] Figure 7 It is a partially enlarged three-dimensional structural schematic diagram of the second mounting frame and the suction cup mounting seat in the present invention. DETAILED DESCRIPTION

[0030] In order to make the above features and advantages of the present invention more obvious and easy to understand, embodiments are given below with reference to the accompanying drawings for detailed description as follows.

[0031] like Figure 1 As shown, Figure 1 This is an integrated diagram of the pressure curve and temperature curve, where the horizontal axis represents time, the vertical axis on the left represents temperature in °C, and the vertical axis on the right represents pressure in mbar. Figure 1 In the figure, the green curve is the pressure setting curve, the blue curve is the actual pressure curve, the red curve is the temperature setting curve, and the purple curve is the actual temperature curve.

[0032] This embodiment provides a glue spot positioning welding process in NTC welding, including the following steps:

[0033] S1. Dispense glue at the location where the module substrate connects the welding plate and the NTC thermistor;

[0034] S2, check whether the position of the glue is accurate, check whether the diameter of the glue is in compliance, if both are in compliance, proceed to the next step;

[0035] S3, attach the welding plate and NTC thermistor to the surface of the module substrate in turn; because the welding piece is smaller than the NTC thermistor, glue is dispensed on the module substrate, and then the welding plate and NTC thermistor are attached to the surface of the module substrate in turn, and the welding plate and NTC thermistor are positioned by the adhesive;

[0036] S4, vacuum welding the module substrate, welding plate and NTC thermistor;

[0037] S41, preheating the module substrate, the welding plate and the NTC thermistor, and reducing the oxides on the module substrate, the welding plate and the NTC thermistor in a formic acid environment;

[0038] S42, perform vacuum welding, and volatilize the glue between the module substrate, the welding plate and the NTC thermistor during welding.

[0039] S43, cooling the finished product.

[0040] The glue applied in step S1 is an adhesive having a volatilization temperature of 250°C.

[0041] In step S41, the preheating temperature is between 190°C and 210°C, and the preferred preheating temperature is 200°C.

[0042] S41 (corresponding Figure 1 The specific steps of the preheating stage and the reduction stage in the process are as follows: evacuate to a vacuum degree below 1 mbar, fill with nitrogen at a flow rate of 60-100 L / min, until the vacuum degree reaches 940-960 mbar, preferably 950 mbar is the best, heat to 200°C, keep the temperature for 20-40s, preferably keep the temperature for 30s for the best effect, evacuate to 1 mbar at the same time, fill with formic acid, at a flow rate of 30 L / min, until the vacuum degree reaches 840-860 mbar, preferably 850 mbar is the best, keep in a 200°C formic acid environment for 140-160s, preferably 150s is the best.

[0043] The welding temperature of step S42 is 250° C.-270° C. A more preferred welding temperature is 260° C., which can ensure both the firmness of welding and the complete volatilization of the glue.

[0044] Step S42 (corresponding to Figure 1 The specific steps of the solder melting and bubble removal stage are as follows: heating to the welding temperature of 260°C, after reaching the target temperature, keep it for 30-40s, preferably 30s, evacuate until the vacuum degree reaches 1mbar, after reaching the vacuum degree, keep it for 60-70s, preferably 60s, fill with nitrogen until the vacuum degree reaches 1000mbar. As the welding temperature rises, the glue begins to evaporate. When the temperature reaches 250°C, the adhesive between the module substrate and the welding plate and between the module substrate and the NTC thermistor evaporates completely, and the welded parts are fully melted.

[0045] Step 43 (corresponding to Figure 1 The cooling temperature in the cooling stage is 40°C-50°C, and the preferred cooling temperature is 45°C. During the cooling process, it is necessary to avoid oxidation of the finished product.

[0046] In this embodiment, glue is dispensed on the surface corresponding to the position where the module substrate is connected to the connecting welding plate and the NTC thermistor, and then the welding plate and the NTC thermistor are sequentially attached to the position. Since the glue is viscous, it can avoid deviation or rolling during mounting, turnover and welding. The packaging process does not require NTC positioning tooling, and the glue will completely evaporate during the vacuum welding process. There is no need to disassemble the tooling after welding, and there is no situation where the NTC is damaged due to disassembly of the tooling. In addition, the glue positioning welding process provided by this solution is cheaper and has lower mounting difficulty than the existing solder paste positioning.

[0047] In the steps S1-S3 of this embodiment, an NTC welding glue dispensing positioning device is used to perform glue dispensing positioning and chip mounting.

[0048] like Figure 2-Figure 7 As shown, this embodiment provides an NTC welding dispensing positioning device, including a transportation component 1, a dispensing component 2, a monitoring component 3 and a patch component 4.

[0049] The conveying component carries the module substrate through the dispensing end of the dispensing component 2, the monitoring end of the monitoring component 3 and the patch end of the patch component 4. The transport component 1 can be moved by a conveyor belt or a movable plate 11 in cooperation with a slide rail 12. In this scheme, the conveying component adopts multiple continuous movable plates 11, and a slide rail 12 is laid under the movable plate 11. A slider and a convex seat are arranged under the movable plate 11. The slider is adapted to the slide rail 12, and a threaded hole is formed on the convex seat. The screw passes through the threaded hole of the convex seat, and the multiple movable plates 11 are driven to move by the rotation of the screw. The reason for using the screw is that the dispensing and patching in this scheme have high requirements on position accuracy, so it is best to use a screw drive.

[0050] The dispensing assembly 2 includes a plurality of dispensing bodies 21, a dispensing front and rear drive assembly, a first mounting frame 23 and a first camera 24. The glue liquid squeezed out by the dispensing body 21 is an adhesive, and the adhesive will completely evaporate at 250 degrees Celsius. Specifically, a plurality of dispensing bodies 21 are installed on the first mounting frame 23 at intervals, and the first camera 24 is installed on the outward side of the first mounting frame 23. The shooting end of the first camera 24 is set downward. The function of the first camera 24 is to judge whether the module substrate has moved into place. The dispensing body 21 includes an extrusion shell 211 and an extrusion screw. The lower end of the extrusion shell 211 is provided with an extrusion head 2111; the upper end side wall of the extrusion shell 211 is provided with a feed port 2112, and the feed port 21 12 is provided with a feed pipe extending upward, the extrusion screw is vertically arranged and rotatably connected in the extrusion shell 211, the upper end of the extrusion screw 212 extends out of the extrusion shell 211, and the circumferential surface of the base screw extending out of the extrusion shell 211 is provided with a pulley 2121, and the first mounting frame 23 is provided with an extrusion motor 2122 on the outer side, and the output end of the extrusion motor 2122 and the pulley 2121 are driven by a belt. Because too much adhesive will affect the welding quality, in order to make the dispensing diameter of the adhesive meet the process requirements, an extrusion screw is used in the dispensing body 21 to accurately control the amount of adhesive.

[0051] The front and rear drive assembly for glue dispensing is used to drive the first mounting frame 23 to move forward and backward. Specifically, the front and rear drive assembly for glue dispensing includes two first gantries 22 and front and rear drive screws for glue dispensing. The two first gantries 22 are arranged at intervals and span the conveying assembly. A first guide rail is arranged on the upper surface of one of the first gantry 22, and a front and rear drive screw for glue dispensing is arranged on the other first gantry 22. The first mounting frame 23 is connected to the first moving seat, and a first sliding block and a first adapting protrusion adapted to the first guide rail are respectively arranged on both sides of the first moving seat. A threaded hole is formed on the first adapting protrusion, and the threaded hole on the first adapting protrusion is adapted to the front and rear drive screw for glue dispensing.

[0052] In another embodiment, the glue dispensing component 2 also includes a glue dispensing left and right drive component, which includes a glue dispensing left and right moving frame 25, a first mounting frame 23 is slidably connected to the surface of the glue dispensing left and right moving frame 25, and the sliding connection is achieved by means of rail matching and screw driving. The two sides of the glue dispensing left and right moving frame 25 are respectively provided with a first sliding block and a first adapting protrusion adapted to the first guide rail, a threaded hole is formed on the first adapting protrusion, and the threaded hole on the first adapting protrusion is adapted to the front and rear driving screws of the glue dispensing. The first movable seat is replaced by the glue dispensing left and right drive component, so that the glue dispensing body 21 can move forward and backward for glue dispensing, and can be adjusted left and right. The purpose of setting the glue dispensing left and right drive component is to use the first camera 24 to shoot and identify, identify that the position of the module substrate carried on the transport component 1 does not correspond (deviation during placement), and the transport component 1 is difficult to retract, and the glue dispensing body 21 is driven to move to the left by the glue dispensing left and right drive components to compensate for the stroke, thereby ensuring the accuracy of glue dispensing.

[0053] The patch assembly 4 is used to sequentially bond the solder piece and the NTC thermistor to the surface of the module substrate. Specifically, the patch assembly 4 includes a feed conveyor belt 41, a second mounting frame 42, a plurality of suction cup mounting seats 43, a plurality of upper and lower drive cylinders 44, a patch left and right drive assembly, and a patch front and rear drive assembly. Specifically, the output ends of the plurality of upper and lower drive cylinders 44 are respectively fixedly connected to the upper surfaces of the plurality of suction cup mounting seats 43, and the plurality of upper and lower drive cylinders 44 are installed on the second mounting frame 42 at intervals. Suction cups 431 are provided on the lower surfaces of the plurality of suction cup mounting seats 43. In this embodiment, the number of the upper and lower drive cylinders 44 is 6, but there are only three upper and lower drive cylinders 44 equipped with suction cup mounting seats 43. The 6 upper and lower drive cylinders 44 are provided to adapt to module substrates of different specifications. The patch left and right drive assembly is used to drive the second mounting frame 42 to move left and right. Specifically, the patch left and right drive assembly includes a patch left and right moving frame 45. The second mounting frame 42 is slidably connected to the surface of the patch left and right moving frame 45, and the sliding connection is achieved by using a rail matching and screw driving method. The patch front and back drive assembly is used to drive the patch left and right drive assembly and the second mounting frame 42 to move forward and backward. Specifically, the patch front and back drive assembly includes two second gantry frames 46 and a patch front and back drive screw. The two second gantry frames 46 are arranged at intervals and span the conveying assembly. The upper surface of one second gantry frame 46 is provided with a second guide rail, and the other second gantry frame 46 is provided with a patch front and back drive screw. The second sliding block and the second adapting protrusion that are adapted to the second guide rail are respectively provided on both sides of the patch left and right moving frame 45. The second adapting protrusion is formed with a threaded hole, and the threaded hole on the second adapting protrusion is adapted to the patch front and back drive screw. The feed conveyor belt 41 is located between the two second gantry frames 46.

[0054] The monitoring component 3 is located between the dispensing component 2 and the patch component 4. The monitoring component 3 includes a second camera, which is used to detect whether the glue on the module substrate meets the requirements.

[0055] In this solution, the glue dispensing component 2 dispenses glue at the specified position of the module substrate, and then the monitoring component 3 monitors whether the glue on the module substrate is in the right position and the right amount. The module substrate with qualified glue dispensing is sent to the patch end of the patch component 4, and the patch component 4 sequentially adheres the solder piece and the NTC thermistor to the top of the module substrate, and then sends it to the vacuum welding equipment for vacuum welding. Since the glue is viscous, it can avoid offset or rolling during mounting, turnover and welding. The packaging process does not require NTC positioning tooling, and there is no NTC damage caused by disassembling the tooling. In addition, during the vacuum welding process, the glue will evaporate to ensure that there is no residue at the solder joint. Compared with the existing solder paste positioning and solder piece processing positioning, it is cheaper and less difficult to mount, and there is no need to disassemble the tooling after welding, and there is no situation where the NTC is damaged due to disassembling the tooling.

[0056] Preferably, the specific steps of step S1 in this scheme are as follows: the moving plate 11 carries the module substrate to the output end of the dispensing body 21, and the first camera 24 takes a picture of the module substrate on the moving plate 11, and judges whether the module substrate has moved into place by the relative position relationship between the module substrate and the center of the picture. After moving into place, the front and rear driving components of the dispensing drive multiple dispensing bodies to dispense glue on the surface of the module substrate.

[0057] The specific steps of step S2 are as follows: the module substrate after glue is applied passes through the second camera, and the second camera shoots the module substrate. The distance between the glue point in the picture and the edge of the module substrate is used to determine whether the glue application position is accurate, and whether there is too much glue by measuring the glue point paper.

[0058] The specific steps of step S3 are as follows: the moving plate 11 carries the module substrate and moves to the bottom of the patch component 4. Through the cooperation of the patch front and rear drive components, the upper and lower drive cylinders 44 and the patch left and right drive components, the solder piece and the NTC thermistor are sequentially attached.

[0059] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A glue spot positioning welding process in NTC welding, characterized in that: The following steps are involved: S1. Dispense glue at the location where the module substrate connects the welding plate and the NTC thermistor; S2, check whether the position of the glue is accurate, check whether the diameter of the glue is in compliance, if both are in compliance, proceed to the next step; S3, attach the welding plate and the NTC thermistor to the surface of the module substrate in sequence; S4, vacuum welding the module substrate, welding plate and NTC thermistor; S41, preheating the module substrate, the welding plate and the NTC thermistor, and reducing the oxides on the module substrate, the welding plate and the NTC thermistor in a formic acid environment; S42, perform vacuum welding, and volatilize the glue between the module substrate, the welding plate and the NTC thermistor during welding.

2. The glue spot positioning welding process in NTC welding according to claim 1 is characterized in that: The preheating temperature in step S41 is between 190°C and 210°C.

3. The glue spot positioning welding process in NTC welding according to claim 2 is characterized in that: The specific steps of step S41 are as follows: evacuate to a vacuum degree below 1 mbar, fill with nitrogen until the vacuum degree reaches 940-960 mbar, heat to 200°C, maintain the temperature for 20-40s, evacuate to 1 mbar, fill with formic acid until the vacuum degree reaches 840-860 mbar, and maintain in a 200°C formic acid environment for 140-160s.

4. The glue spot positioning welding process in NTC welding according to claim 3 is characterized in that: The flow rate when filling with nitrogen is 60-100L / min.

5. The glue spot positioning welding process in NTC welding according to claim 3 is characterized in that: The flow rate when filling with formic acid is 30L / min.

6. The glue spot positioning welding process in NTC welding according to claim 1 is characterized in that: The welding temperature in step S42 is 250°C-270°C.

7. The glue spot positioning welding process in NTC welding according to claim 6 is characterized in that: The specific steps of step S42 are as follows: heating to the welding temperature of 260°C, maintaining for 30-40 seconds after reaching the target temperature, evacuating to a vacuum degree of 1 mbar, maintaining for 60-70 seconds after reaching the vacuum degree, and filling with nitrogen to a vacuum degree of 1000 mbar.

8. The glue spot positioning welding process in NTC welding according to claim 1 is characterized in that: The step S4 also includes a step S43; the step S43 is to cool the finished product.

9. The glue spot positioning welding process in NTC welding according to claim 8, characterized in that: The cooling temperature in step 43 is 40°C-50°C.

10. The glue spot positioning welding process in NTC welding according to claim 1, characterized in that: The glue liquid is an adhesive, and the complete volatilization temperature of the adhesive is 250°C.

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