A planar transformer core SMT mounting process

Abstract

The present invention discloses a planar transformer core SMT mounting process, which belongs to the technical field of pre-embedded magnetic cores of printed circuit boards. It converts the traditional laminate mounting device method into a mounting method using SMT mounting equipment, and controls the coating amount and shape of the glue on the PCBA and the device, thereby controlling the height of the device after bonding; finally, a method for measuring and controlling the position offset is given through a logical algorithm; thereby, the yield rate and production efficiency of the planar transformer core mounting are effectively improved. Therefore, the planar transformer core SMT mounting process of the present invention solves the technical problem of how to improve the assembly efficiency of the planar transformer core integrated into the PCBA.

Description

Technical Field

[0001] The invention relates to the technical field of pre-buried magnetic cores of printed circuit boards, and in particular to a SMT mounting process for a magnetic core of a planar transformer. Background Art

[0002] PCB planar transformer is a special transformer structure, which arranges the main and secondary windings in different PCB layers, so that the magnetic circuit of the transformer is completely located inside the PCB board, thus forming a planar structure. This design not only saves space, but also improves the performance and reliability of the transformer.

[0003] Specifically, in a DC-DC converter, if the output is required to be isolated from the input, or if multiple sets of output voltages are required, an isolation transformer must be used. The current development trend of switching power supplies is higher efficiency, smaller size, and lighter weight, especially for module power supplies used in aerospace, automotive electronics and other application fields, which have more stringent requirements. However, traditional isolation transformers have seriously restricted the further development of switching power supplies in terms of efficiency, volume, and weight. At the same time, since the main parameters involved in the transformer, such as voltage, current, frequency, ratio, temperature, leakage inductance, loss, and external dimensions, are very complex; therefore, there has been no ready-made transformer available for selection like other electronic components, and it is often necessary to go through tedious calculations to select the core and winding wire. Moreover, the winding method of the winding also has a great influence on the performance of the transformer. In addition, many important parameters of the transformer are not easy to measure, which brings a certain degree of blindness to the use, and it is difficult to achieve satisfactory results in terms of frequency response, leakage inductance, volume, and heat dissipation.

[0004] In order to solve the above technical problems, PCB planar transformers have been widely used. This type of transformer usually uses a planar RM, EI, PQ or EE high-frequency power ferrite core, which has low core loss at high frequencies of 200~700kHz. In terms of winding structure, it is made of multi-layer printed circuit boards, which can meet the design requirements of high power density and miniaturization of DC-DC converters. At present, in the installation process of transformer cores, manual mounting is required in most cases, which has a great impact on processing efficiency. If the core can be buried and automated assembly can be achieved at the same time, it may provide support for reducing processing costs.

[0005] Based on this, the patent technical document with publication number CN102933040A discloses a method for manufacturing a PCB board with an embedded inductor device, which includes the following steps: Step 1. Provide a ring-shaped magnetic core and a PCB board to be embedded with the magnetic core; Step 2. Open an annular groove at a corresponding position of the PCB board to be embedded with the magnetic core, and drill a plurality of holes at the bottom of the annular groove; Step 3. Place the annular magnetic core in the annular groove, and fix the annular magnetic core in the annular groove by a lamination process; Step 4. Remove the glue from the surface of the magnetic core; Step 5. Form a plurality of first through holes in the corresponding annular groove of the PCB board, and form a plurality of second through holes outside the corresponding annular groove of the PCB board corresponding to the first through holes; Step 6. Copper-plate the first and second through holes, and electrically connect the copper layers in the first and second through holes to form a magnetic core winding, thereby forming an inductor device, and thereby obtaining a PCB board with an embedded inductor device; Step 7. Test the inductance value by testing the inductor device, and record it.

[0006] However, the manufacturing method of the PCB board with embedded inductor devices disclosed above still has the technical problems of low pre-embedded magnetic core yield and low assembly process efficiency. Specifically, in the existing technology, the specific process is: using a flat-bottom milling cutter to open an annular groove at the corresponding position of the PCB board where the magnetic core is embedded, and drilling four holes at the bottom of the annular groove; and the depth of the annular groove is 0.2mm greater than the thickness of the magnetic core, that is, the magnetic core is lower than the board surface when embedded in the PCB; finally, the annular magnetic core is placed in the annular groove, and the annular magnetic core is fixed in the annular groove through a lamination process. In this process, the lamination process is prone to glue flow, which affects the pre-embedded magnetic core yield. In addition, in the lamination process, if the pressure on the magnetic core is too small, the magnetic core will not be embedded in place; if the magnetic core is too large, the magnetic core is also easily compressed and broken. Therefore, the broken magnetic core needs to be disassembled and reassembled, which affects the assembly process efficiency. Summary of the invention

[0007] Based on this, it is necessary to provide a planar transformer core SMT mounting process to improve the technical problem of how to improve the assembly efficiency of the planar transformer core integrated into the PCBA.

[0008] A planar transformer core SMT mounting process, comprising the following steps:

[0009] S1: Control the incoming material size of the magnetic core components according to the preset standards, and then use the preset PCBA tooling to limit and clamp the PCBA to be processed;

[0010] S2: Use the dispensing equipment to dispense glue at the preset position of the clamped PCBA, and control the dispensing size, number of glue strips, dispensing track and dispensing position at that location; then, use the SMT mounting equipment to absorb the corresponding magnetic core components and mount them on the dispensing position on the PCBA, and measure and control the height of the mounted magnetic core components;

[0011] S3: Use the PCBA tooling to flip the PCBA with the magnetic core device mounted on one side after curing by 180 degrees, and then dispense glue to the preset position of the magnetic core device mounted on the other side of the PCBA, and control the glue dispensing size, number of glue strips, glue dispensing track and glue dispensing position at this location; then, use the SMT placement equipment to pick up the corresponding magnetic core-to-core device and mount it on the aforementioned glue dispensing position, and measure and control the height of the mounted magnetic core docking device;

[0012] S4: Measure and control the position deviation value of the magnetic core components mounted on both sides of the PCBA;

[0013] S5: Conduct performance testing and control on products whose position deviation meets the design requirements.

[0014] Specifically, the dispensing parameters of the material with the transformer type of LS flyback and the core type of PQ core in step S2 are: two strips of glue are applied along the two sides of the core center column, the dispensing trajectory is arc-shaped, the length of each glue strip is at least 14 mm, the width of each glue strip is at least 0.85 mm, and the height of each glue strip is at least 0.46 mm.

[0015] More specifically, the parameters of the dispensing trajectory of the material with the transformer type of LS flyback and the core type of PQ core in step S2 are: inner diameter of R4.4±0.1mm, cpk=2.96, outer diameter of R9±0.2, cpk=3.81, and arc angle of 45 degrees.

[0016] Specifically, the dispensing parameters of the material with the transformer type of HS flyback and the core type of EE core in step S2 are: two strips of glue are dispensed along each side of the core center column, the dispensing trajectory is a straight line, the length of each glue strip is at least 14.75 mm, the width of each glue strip is at least 0.85 mm, and the height of each glue strip is at least 0.46 mm.

[0017] More specifically, the parameters of the dispensing track of the material with the transformer type of HS flyback and the core type of EE core in step S2 are as follows: the spacing between the inner edges of the two straight tracks is controlled to be 5.7±0.2mm, cpk=5.28, the spacing between the outermost edges of the two straight tracks is controlled to be 20.0-20.6mm, cpk=2.81, and the length of each straight track is controlled to be 15±0.25mm, cpk=2.24.

[0018] Specifically, the dispensing parameters of the material with the transformer type of LS flyback and the core type of PQ core in step S3 are: one dispensing line along each end face of the two side columns of the core, the dispensing trajectory is a straight line with endpoints, the length of each glue strip is at least 13.6 mm, the width of each glue strip is at least 0.97 mm, and the height of each glue strip is at least 0.46 mm.

[0019] More specifically, the parameters of the dispensing track of the material with the transformer type of LS flyback and the core type of PQ core in step S3 are as follows: the spacing between the inner edges of the two straight line tracks is controlled to be at least 12 mm, cpk=7.93, the spacing between the outermost edges of the two straight line tracks is controlled to be 20.5±0.4 mm, cpk=3.60, and the length of each straight line track is controlled to be 14±0.4 mm, cpk=6.64; each end of each straight line track is dispensed separately once, and 1 mg of glue is dispensed each time.

[0020] Specifically, the dispensing parameters of the material with the transformer type of HS flyback and the core type of EE core in step S3 are: one dispensing line along each end face of the two side columns of the core, the dispensing trajectory is a straight line, the length of each glue strip is at least 14.75 mm, the width of each glue strip is at least 0.97 mm, and the height of each glue strip is at least 0.46 mm.

[0021] More specifically, the parameters of the dispensing track of the material with the transformer type of HS flyback and the core type of EE core in step S3 are as follows: the spacing between the inner edges of the two straight tracks is controlled to be 20.0-20.6mm, cpk=2.81, the spacing between the outermost edges of the two straight tracks is controlled to be 25.5-26.1mm, cpk=2.16, and the length of each straight track is controlled to be 15±0.25mm, cpk=2.24.

[0022] More specifically, in step S4, the specific method for measuring and controlling the position deviation value of the magnetic core components mounted on both sides of the PCBA is as follows:

[0023] S41: determining the actual offset position of the magnetic core component and the magnetic core-attached component;

[0024] S42: Draw two side lines of the magnetic core device and determine a first intersection point of the two side lines;

[0025] S43: Continue to draw two side lines of the magnetic core-attached device, and determine the vertical distances a and b and the angle θ between the first intersection point and the two side lines of the magnetic core-attached device;

[0026] S44: Draw a relationship diagram between the offset and the sensitivity, and obtain a sensitivity-offset limit curve;

[0027] S45: drawing a relationship diagram between the offset and the bonding strength, and obtaining a bonding strength-offset limit curve;

[0028] S46: The inductance-offset limit curve is intersected with the bonding strength-offset limit curve. The lower side of the intersecting surface is the control safety zone. The offset position of the core device and the core-to-core device is controlled in production according to the control safety zone.

[0029] In summary, the SMT mounting process of a planar transformer magnetic core of the present invention comprises the following steps: first, the incoming material size of the magnetic core device is controlled according to a preset standard, and then the PCBA to be processed is limitedly clamped by using a preset PCBA tooling; then, a dispensing device is used to dispense glue at a preset position of the clamped PCBA, and the dispensing size, number of glue strips, dispensing track and dispensing position at the location are controlled; then, the SMT mounting device is used to absorb the corresponding magnetic core device and mount it on the dispensing position on the PCBA, and the height of the mounted magnetic core device is measured and controlled; then, the PCB is used to A tool turns the PCBA with the magnetic core device mounted on one side after curing by 180 degrees, and then dispenses glue at the preset position of the magnetic core device mounted on the other side of the PCBA, and controls the glue dispensing size, glue strip number, glue dispensing track and glue dispensing position at this place; then, use the SMT mounting equipment to absorb the corresponding magnetic core pair mounting device to mount it on the aforementioned position where glue dispensing is completed, and measure and control the height of the mounted magnetic core docking device; finally, respectively measure and control the position deviation value of the magnetic core device mounted on both sides of the PCBA, and perform performance test control on the product whose position deviation meets the design requirements. Therefore, the SMT mounting process of a planar transformer magnetic core of the present invention converts the traditional method of laminating mounting devices into a method of attaching using SMT mounting equipment, and controls the coating amount and shape of the glue dispensing on the PCBA and the device, thereby controlling the height of the device after bonding; finally, a method of measuring and controlling the position offset is given through a logical algorithm; thus, the yield rate and production efficiency of the planar transformer magnetic core mounting are effectively improved. Therefore, the planar transformer core SMT mounting process of the present invention solves the technical problem of how to improve the assembly efficiency of the planar transformer core integrated into the PCBA. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a PCB planar transformer;

[0031] Figure 2 It is a schematic diagram of the glue dispensing track of the material of the PQ core on one side of the PCBA in the SMT mounting process of the planar transformer core of the present invention;

[0032] Figure 3 It is a schematic diagram of the glue dispensing track of the material of the EE core on one side of the PCBA in the SMT mounting process of the planar transformer core of the present invention;

[0033] Figure 4 It is a schematic diagram of the glue dispensing track of the material of the PQ core on the other side of the PCBA in the SMT mounting process of the planar transformer core of the present invention;

[0034] Figure 5 It is a schematic diagram of the glue dispensing track of the material of the EE core on the other side of the PCBA in the SMT mounting process of the planar transformer core of the present invention;

[0035] Figure 6 It is a schematic diagram of a method for measuring the offset of the magnetic core mounting position in the SMT mounting process of a planar transformer magnetic core of the present invention;

[0036] Figure 7 It is a schematic diagram of an offset limit curve of the offset of the magnetic core mounting position in the SMT mounting process of a planar transformer magnetic core of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0043] For details, please refer to Figure 1 , Figure 1A structure of a PCB planar transformer is disclosed, which includes: a first magnetic core device 1, a second magnetic core device 2, a multilayer printed circuit board 3 and a slotted structure 4; the first magnetic core device 1 and the second magnetic core device 2 are arranged opposite to each other, and the multilayer printed circuit board 3 is arranged between the first magnetic core device 1 and the second magnetic core device 2; the slotted structure 4 is arranged through the multilayer printed circuit board 3, and the first magnetic core device 1 and the second magnetic core device 2 are connected in the slotted structure 4.

[0044] Furthermore, in a specific embodiment, the multilayer printed circuit board 3 has a first circuit board layer 301, a second circuit board layer 302, a third circuit board layer 303 and a fourth circuit board layer 304; a flat continuous copper spiral wire 301a is etched in each circuit board layer to serve as a winding structure of a transformer; a connecting wire structure 301b is provided between each circuit board layer to serve as an electrical connection between each winding.

[0045] Based on this, the current technical difficulty of pre-embedded magnetic cores in PCBA lies in how to achieve stable connection between each circuit board layer, or how to achieve stable and efficient connection between magnetic core devices and between magnetic core devices and PCBA.

[0046] Furthermore, the present invention provides a planar transformer core SMT mounting process, which comprises the following steps:

[0047] S1: Control the incoming material size of the magnetic core components according to the preset standards, and then use the preset PCBA tooling to limit and clamp the PCBA to be processed;

[0048] S2: Use the dispensing equipment to dispense glue at the preset position of the clamped PCBA, and control the dispensing size, number of glue strips, dispensing track and dispensing position at that location; then, use the SMT mounting equipment to absorb the corresponding magnetic core components and mount them on the dispensing position on the PCBA, and measure and control the height of the mounted magnetic core components;

[0049] S3: Use the PCBA tooling to flip the PCBA with the magnetic core device mounted on one side after curing by 180 degrees, and then dispense glue to the preset position of the magnetic core device mounted on the other side of the PCBA, and control the glue dispensing size, number of glue strips, glue dispensing track and glue dispensing position at this location; then, use the SMT placement equipment to pick up the corresponding magnetic core-to-core device and mount it on the aforementioned glue dispensing position, and measure and control the height of the mounted magnetic core docking device;

[0050] S4: Measure and control the position deviation value of the magnetic core components mounted on both sides of the PCBA;

[0051] S5: Conduct performance testing and control on products whose position deviation meets the design requirements.

[0052] Specifically, a planar transformer core SMT mounting process of the present invention converts the traditional laminate mounting device method into a mounting method using SMT mounting equipment, and controls the coating amount and shape of the glue dots on the PCBA and the device, thereby controlling the height of the device after bonding; finally, a method for measuring and controlling the position offset is given through a logic algorithm; thereby, the process production efficiency of the planar transformer core mounting is effectively improved.

[0053] Specifically, the glue used in the SMT mounting process of the planar transformer core of the present invention is a modified epoxy resin, and its model is EW6315WS-1M. The appearance of this modified epoxy resin glue is white, the viscosity is 42000mPa・s, the thixotropic index is 5.6, and the specific gravity is -1.33g / cm 3 The curing parameters of this modified epoxy resin glue are: 25℃-150℃ ramp time is 3 minutes; 150℃ isothermal time is 10 minutes.

[0054] Specifically, the dispensing equipment used in the SMT mounting process of the planar transformer core of the present invention is a GKG piezoelectric jet valve, whose model is GV 3000H. The needle diameter of the dispensing equipment is 2.0mm, and the nozzle is a 0.3mm flat nozzle; the single dispensing height is 3mm, the heating temperature is 45°C, the feed gas pressure is 0.16MPa, and the single point weighing is 0.036mg.

[0055] Furthermore, in a specific embodiment of the SMT mounting process of a planar transformer core of the present invention, the dispensing parameters of the material of the transformer type LS flyback and the core type PQ core in step S2 are: two strips of glue are dispensed along the two sides of the core center column, the dispensing track is arc-shaped, the length of each strip is at least 14mm, the width of each strip is at least 0.85mm, and the height of each strip is at least 0.46mm. For details, please continue to refer to Figure 2 ,like Figure 2 As shown, the parameters of the aforementioned dispensing track are specifically: an inner diameter of R4.4±0.1mm, cpk=2.96, an outer diameter of R9±0.2, cpk=3.81, and an arc of 45 degrees.

[0056] Furthermore, in a specific embodiment of the SMT mounting process of a planar transformer core of the present invention, the dispensing parameters of the material of the HS flyback transformer type and the EE core type in step S2 are: two strips of glue are dispensed along the two sides of the core center column, the dispensing track is a straight line, the length of each strip is at least 14.75mm, the width of each strip is at least 0.85mm, and the height of each strip is at least 0.46mm. For details, please continue to refer to Figure 3 ,like Figure 3 As shown, the parameters of the aforementioned dispensing track are specifically as follows: the spacing between the inner sides of the two straight tracks is controlled to be 5.7±0.2mm, cpk=5.28, the spacing between the outermost sides of the two straight tracks is controlled to be 20.0-20.6mm, cpk=2.81, and the length of each straight track is controlled to be 15±0.25mm, cpk=2.24.

[0057] Furthermore, in a specific embodiment of the SMT mounting process of a planar transformer core of the present invention, the dispensing parameters of the material of the transformer type LS flyback and the core type PQ core in step S3 are: one dispensing line is applied along each end face of the two side columns of the core, the dispensing track is a straight line with endpoints, the length of each strip is at least 13.6mm, the width of each strip is at least 0.97mm, and the height of each strip is at least 0.46mm. For details, please continue to refer to Figure 4 ,like Figure 4 As shown, the parameters of the aforementioned dispensing track are specifically as follows: the spacing between the inner edges of the two straight line tracks is controlled to be at least 12mm, cpk=7.93, the spacing between the outermost edges of the two straight line tracks is controlled to be 20.5±0.4mm, cpk=3.60, the length of each straight line track is controlled to be 14±0.4mm, cpk=6.64; each straight line track is individually dispensed once at both ends, and 1mg of glue is dispensed each time.

[0058] Furthermore, in a specific embodiment of the SMT mounting process of a planar transformer core of the present invention, the dispensing parameters of the material of the HS flyback transformer type and the EE core type in step S3 are: one dispensing line is applied along each end face of the two side columns of the core, the dispensing track is a straight line, the length of each strip is at least 14.75mm, the width of each strip is at least 0.97mm, and the height of each strip is at least 0.46mm. For details, please continue to refer to Figure 5 ,like Figure 5 As shown, the parameters of the aforementioned dispensing track are specifically as follows: the spacing between the inner edges of the two straight line tracks is controlled to be 20.0-20.6 mm, cpk=2.81, the spacing between the outermost edges of the two straight line tracks is controlled to be 25.5-26.1 mm, cpk=2.16, and the length of each straight line track is controlled to be 15±0.25 mm, cpk=2.24.

[0059] Furthermore, in order to ensure the vibration resistance of the magnetic core, the contact area of ​​the magnetic core can be increased; for example, in step S3, for materials with LS flyback transformer type and PQ core type, glue can be applied to the surface of the middle column of the magnetic core at several locations in step S3, and it is ensured that there is a glue point at the center of the middle column of the magnetic core. In addition, for materials with HS flyback transformer type and EE core type, glue application tracks can be added to the surface of the middle column of the magnetic core in step S3, and the glue application tracks are linear, and the length of the glue strip is at least 13.6 mm, the width of the glue strip is at least 0.97 mm, and the height of the glue strip is at least 0.46 mm.

[0060] For further information, please refer to Figure 6 to Figure 7 Since the offset of the core to the sticker will affect the core function indicators, such as inductance and strength, the offset measurement indicator diagram is as follows Figure 6 As shown; the schematic diagram of the offset limit curve is as follows Figure 7 As shown; in the aforementioned step S4, the specific method for measuring and controlling the position deviation value of the magnetic core components mounted on both sides of the PCBA is as follows:

[0061] S41: determining the actual offset position of the magnetic core component and the magnetic core-attached component;

[0062] S42: Draw two side lines of the magnetic core device and determine a first intersection point of the two side lines;

[0063] S43: Continue to draw two side lines of the magnetic core-attached device, and determine the vertical distances a and b and the angle θ between the first intersection point and the two side lines of the magnetic core-attached device;

[0064] S44: Draw a relationship diagram between the offset and the sensitivity, and obtain a sensitivity-offset limit curve;

[0065] S45: drawing a relationship diagram between the offset and the bonding strength, and obtaining a bonding strength-offset limit curve;

[0066] S46: The inductance-offset limit curve is intersected with the bonding strength-offset limit curve. The lower side of the intersecting surface is the control safety zone. The offset position of the core device and the core-to-core device is controlled in production according to the guidance of the safety zone.

[0067] In summary, the SMT mounting process of a planar transformer magnetic core of the present invention comprises the following steps: first, the incoming material size of the magnetic core device is controlled according to a preset standard, and then the PCBA to be processed is limitedly clamped by using a preset PCBA tooling; then, a dispensing device is used to dispense glue at a preset position of the clamped PCBA, and the dispensing size, number of glue strips, dispensing track and dispensing position at the location are controlled; then, the SMT mounting device is used to absorb the corresponding magnetic core device and mount it on the dispensing position on the PCBA, and the height of the mounted magnetic core device is measured and controlled; then, the PCB is used to A tool turns the PCBA with the magnetic core device mounted on one side after curing by 180 degrees, and then dispenses glue at the preset position of the magnetic core device mounted on the other side of the PCBA, and controls the glue dispensing size, glue strip number, glue dispensing track and glue dispensing position at this place; then, use the SMT mounting equipment to absorb the corresponding magnetic core pair mounting device to mount it on the aforementioned position where glue dispensing is completed, and measure and control the height of the mounted magnetic core docking device; finally, respectively measure and control the position deviation value of the magnetic core device mounted on both sides of the PCBA, and perform performance test control on the product whose position deviation meets the design requirements. Therefore, the SMT mounting process of a planar transformer magnetic core of the present invention converts the traditional method of laminating mounting devices into a method of attaching using SMT mounting equipment, and controls the coating amount and shape of the glue dispensing on the PCBA and the device, thereby controlling the height of the device after bonding; finally, a method of measuring and controlling the position offset is given through a logical algorithm; thus, the yield rate and production efficiency of the planar transformer magnetic core mounting are effectively improved. Therefore, the planar transformer core SMT mounting process of the present invention solves the technical problem of how to improve the assembly efficiency of the planar transformer core integrated into the PCBA.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A planar transformer core SMT mounting process, characterized in that: It includes the following steps: S1: Control the incoming material size of the magnetic core components according to the preset standards, and then use the preset PCBA tooling to limit and clamp the PCBA to be processed; S2: Use the dispensing equipment to dispense glue at the preset position of the clamped PCBA, and control the dispensing size, number of glue strips, dispensing track and dispensing position at that location; then, use the SMT mounting equipment to absorb the corresponding magnetic core components and mount them on the dispensing position on the PCBA, and measure and control the height of the mounted magnetic core components; S3: Use the PCBA tooling to flip the PCBA with the magnetic core device mounted on one side after curing by 180 degrees, and then dispense glue to the preset position of the magnetic core device mounted on the other side of the PCBA, and control the glue dispensing size, number of glue strips, glue dispensing track and glue dispensing position at this location; then, use the SMT placement equipment to pick up the corresponding magnetic core-to-core device and mount it on the aforementioned glue dispensing position, and measure and control the height of the mounted magnetic core docking device; S4: Measure and control the position deviation value of the magnetic core components mounted on both sides of the PCBA. The measurement and control steps include: S41: determining the actual offset position of the magnetic core component and the magnetic core-attached component; S42: Draw two side lines of the magnetic core device and determine a first intersection point of the two side lines; S43: Continue to draw two side lines of the magnetic core-attached device, and determine the vertical distances a and b and the angle θ between the first intersection point and the two side lines of the magnetic core-attached device; S44: Draw a relationship diagram between the offset and the sensitivity, and obtain a sensitivity-offset limit curve; S45: drawing a relationship diagram between the offset and the bonding strength, and obtaining a bonding strength-offset limit curve; S46: The inductance-offset limit curve is intersected with the bonding strength-offset limit curve. The lower side of the intersecting surface is the control safety zone. The offset position of the core device and the core-to-core device is controlled in production according to the control safety zone. S5: Conduct performance testing and control on products whose position deviation meets the design requirements.

2. The planar transformer core SMT mounting process according to claim 1, characterized in that: The dispensing parameters of the material with the transformer type of LS flyback and the core type of PQ core in step S2 are: two strips of glue are dispensed along the two sides of the core center column, the dispensing track is arc-shaped, the length of each glue strip is at least 14mm, the width of each glue strip is at least 0.85mm, and the height of each glue strip is at least 0.46mm.

3. The SMT mounting process for a planar transformer core according to claim 2, characterized in that: The parameters of the dispensing trajectory of the material with the transformer type of LS flyback and the core type of PQ core in step S2 are as follows: the inner diameter R is 4.4±0.1mm, cpk=2.96, the outer diameter R is 9±0.2mm, cpk=3.81, and the arc angle is 45 degrees.

4. The SMT mounting process for a planar transformer core according to claim 1, characterized in that: The dispensing parameters of the material with the transformer type of HS flyback and the core type of EE core in step S2 are: two strips of glue are dispensed along the two sides of the core center column, the dispensing trajectory is a straight line, the length of each glue strip is at least 14.75mm, the width of each glue strip is at least 0.85mm, and the height of each glue strip is at least 0.46mm.

5. The SMT mounting process for a planar transformer core according to claim 4, characterized in that: The parameters of the dispensing track of the material with the transformer type of HS flyback and the core type of EE core in step S2 are as follows: the spacing between the inner edges of the two straight tracks is controlled to be 5.7±0.2mm, cpk=5.28, the spacing between the outermost edges of the two straight tracks is controlled to be 20.0-20.6mm, cpk=2.81, and the length of each straight track is controlled to be 15±0.25mm, cpk=2.

24.

6. The SMT mounting process for a planar transformer core according to claim 1, characterized in that: The dispensing parameters of the material with the transformer type of LS flyback and the core type of PQ core in step S3 are: one dispensing line is applied along each end face of the two side columns of the core, the dispensing track is a straight line with endpoints, the length of each strip is at least 13.6 mm, the width of each strip is at least 0.97 mm, and the height of each strip is at least 0.46 mm.

7. The SMT mounting process for a planar transformer core according to claim 6, characterized in that: The parameters of the dispensing track of the material with the transformer type of LS flyback and the core type of PQ core in step S3 are as follows: the spacing between the inner edges of the two straight tracks is controlled to be at least 12mm, cpk=7.93, the spacing between the outermost edges of the two straight tracks is controlled to be 20.5±0.4mm, cpk=3.60, and the length of each straight track is controlled to be 14±0.4mm, cpk=6.64; each end of each straight track is dispensed separately once, and 1mg is dispensed each time.

8. The SMT mounting process for a planar transformer core according to claim 1, characterized in that: The dispensing parameters of the material with the transformer type of HS flyback and the core type of EE core in step S3 are: one dispensing line is made along each end face of the two side columns of the core, the dispensing track is a straight line, the length of each strip is at least 14.75 mm, the width of each strip is at least 0.97 mm, and the height of each strip is at least 0.46 mm.

9. The SMT mounting process for a planar transformer core according to claim 8, characterized in that: The parameters of the dispensing track of the material with the transformer type of HS flyback and the core type of EE core in step S3 are as follows: the spacing between the inner edges of the two straight tracks is controlled to be 20.0-20.6mm, cpk=2.81, the spacing between the outermost edges of the two straight tracks is controlled to be 25.5-26.1mm, cpk=2.16, and the length of each straight track is controlled to be 15±0.25mm, cpk=2.24.

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