A design method for DC resistance of PCB planar transformer

Abstract

The present invention relates to the field of electronic information engineering technology, and discloses a PCB planar transformer DC resistance design method, including the following steps: S1 calculates the winding DC resistance through a formula based on conventional resistance; S2 calculates the conductor cross-sectional area S and etching factor of the PCB product through a formula; S3 derives the PCB DC resistance through a formula; S4 determines the DCR design range; S5 determines whether the winding DCR of the above design meets the requirements; S6 calculates the line width and copper thickness design values ​​using a reverse calculation formula; S7 develops DCR design calculation software through the above derivation steps. In the present invention, based on the resistance calculation formula, combined with the process copper thickness tolerance, line width tolerance, etching factor manufacturing capability and PCB conductor specification shape, an effective calculation formula for the PCB planar transformer DC resistance (DCR) is output, the control range of copper thickness and line width, the influencing factors related to DC resistance, is accurately defined, and the DCR design calculation software is developed using this derivation formula to improve accuracy and work efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of electronic information engineering, and in particular to a method for designing a DC resistance of a PCB planar transformer. Background Art

[0002] With the development of electronic science and technology, people have entered the information society, and various portable electronic products have emerged to change people's daily lives. People can communicate anytime and anywhere through mobile phones, especially the smart phones that have integrated communication, Internet access, games, and entertainment functions in recent years, which have greatly enriched people's daily lives; although people have adopted various measures to solve the power saving problem of electronic products, these electronic products are still very power-consuming. Once the power stored in the rechargeable battery is used up, people must charge them. Ordinary charging heads are traditional winding transformer designs. In order to improve charging efficiency and reduce the size of the charging head, the internal design of the charging head has gradually changed to a PCB planar transformer design mode.

[0003] Traditional transformers are large in size and have high power loss, especially at high frequencies, where the power loss is more obvious. PCB planar transformers have the advantages of small size, low power consumption, high-frequency performance and good heat dissipation performance. PCB planar transformers will be widely used in communication power supplies, digital cameras, digital televisions, mobile phones, laptops, automotive electronics, power equipment, aerospace power supplies, radar power supplies and other fields. During the manufacturing process, due to the requirements of low power consumption and high-frequency performance, it is necessary to measure and control the DCR (direct current resistance), inductance, coupling voltage, etc. of the PCB planar transformer. Among them, the control requirement of DCR is at the mΩ level to check whether there are defects, short circuits, open circuits and other abnormalities in the windings; this requires more accurate calculations in the front-end design and the definition of a reasonable control range for each influencing factor to ensure that the DCR value of the final product is within the customer's requirements.

[0004] For PCB planar transformers, to accurately design and define the control range of factors related to winding DCR, it is necessary to consider the copper thickness tolerance, line width tolerance and etching factor during the manufacturing process. To this end, we propose a PCB planar transformer DC resistance design method. Summary of the invention

[0005] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a method for designing the DC resistance of a PCB planar transformer.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme, a PCB planar transformer DC resistance design method, comprising the following steps:

[0007] S1 calculates the winding DC resistance through the formula based on conventional resistance;

[0008] S2 calculates the conductor cross-sectional area S and etching factor of PCB products through the formula;

[0009] S3 derives the PCB DC resistance through the formula;

[0010] S4 determines the DCR design range;

[0011] S5 determines whether the winding DCR designed above meets the requirements;

[0012] S6 uses the reverse calculation formula to calculate the design value of line width and copper thickness;

[0013] S7 developed the DCR design calculation software through the above derivation steps.

[0014] Preferably, the calculation formula of the winding DC resistance is:

[0015] R = ρL / S (1);

[0016] Where: R-resistance (Ω), ρ-resistivity (Ωmm 2 / m), L-wire length (inch), S-conductor cross-sectional area (mil 2 ).

[0017] Preferably, the calculation formula of the wire cross-sectional area S and the etching factor is:

[0018] S = (W1 + W2) * T / 2 (2);

[0019] Q = 2*T / (W1-W2) (3);

[0020] Where: S-conductor cross-sectional area (mil 2 ), W1-lower line width (mil), W2-upper line width (mil), T-copper thickness (mil), Q-etching factor.

[0021] Preferably, the PCB DC resistance is derived by formulas (1), (2) and (3):

[0022]

[0023] Preferably, the DCR design range formula determined in S4 is:

[0024]

[0025]

[0026] Preferably, the line width inverse formula in S6 is:

[0027]

[0028] The formula for inverse calculation of copper thickness in S6 is:

[0029]

[0030] Beneficial Effects

[0031] The present invention provides a method for designing DC resistance of a PCB planar transformer, which has the following beneficial effects:

[0032] The invention is based on the resistance calculation formula, combined with the DC resistance principle, combined with the process copper thickness tolerance, line width tolerance, etching factor manufacturing capability and PCB conductor specification and shape, outputs an effective calculation formula for the DC resistance (DCR) of the PCB planar transformer, accurately defines the control range of copper thickness and line width, which are factors affecting DC resistance, and ensures that the DC resistance test of the final product meets customer requirements. The derived formula is used to develop DCR design calculation software to improve accuracy and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the overall flow chart of the present invention;

[0034] Figure 2 It is a schematic diagram of the cross-section of the conductor of the PCB planar transformer of the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0036] Embodiment: A method for designing DC resistance of a PCB planar transformer, such as Figure 1-2 As shown, the following steps are included:

[0037] S1 calculates the winding DC resistance through the formula based on conventional resistance;

[0038] S2 calculates the conductor cross-sectional area S and etching factor of PCB products through the formula;

[0039] S3 derives the PCB DC resistance through the formula;

[0040] S4 determines the DCR design range;

[0041] S5 determines whether the winding DCR designed above meets the requirements;

[0042] S6 uses the reverse calculation formula to calculate the design value of line width and copper thickness;

[0043] S7 developed the DCR design calculation software through the above derivation steps.

[0044] Preferably, the calculation formula of the winding DC resistance is:

[0045] R = ρL / S (1);

[0046] Where: R-resistance (Ω), ρ-resistivity (Ωmm 2 / m), L-wire length (inch), S-conductor cross-sectional area (mil 2 ).

[0047] The calculation formula of the wire cross-sectional area S and the etching factor is:

[0048] S = (W1 + W2) * T / 2 (2);

[0049] Q = 2*T / (W1-W2) (3);

[0050] Where: S-conductor cross-sectional area (mil 2 ), W1-lower line width (mil), W2-upper line width (mil), T-copper thickness (mil), Q-etching factor.

[0051] The PCB DC resistance is derived by formulas (1), (2) and (3):

[0052]

[0053] The DCR design range formula determined in S4 is:

[0054]

[0055]

[0056] The reverse line width formula in S6 is:

[0057]

[0058] The formula for inverse calculation of copper thickness in S6 is:

[0059]

[0060] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining 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 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 PCB planar transformer DC resistance design method, characterized in that: The following steps are involved: S1: Calculate the winding DC resistance by formula based on conventional resistance; S2: Calculate the conductor cross-sectional area S and etching factor of the PCB product through the formula; S3: Derivation of PCB DC resistance through formula; S4: Determine the DCR design range; S5: Determine whether the winding DCR designed above meets the requirements; S6: Use the reverse calculation formula to calculate the design value of line width and copper thickness; S7: Develop DCR design calculation software through the above derivation steps; The calculation formula of the winding DC resistance is: R = ρL / S(1); Where: R-resistance (Ω), ρ-resistivity (Ωmm 2 / m), L-wire length (inch), S-conductor cross-sectional area (mil2); The calculation formula of the wire cross-sectional area S and the etching factor is: S = (W1 + W2) * T / 2 (2); Q = 2*T / (W1-W2)(3); Where: S-conductor cross-sectional area (mil2), W1-lower line width (mil), W2-upper line width (mil), T-copper thickness (mil), Q-etching factor; The PCB DC resistance is derived by formulas (1), (2) and (3): The DCR design range formula determined in S4 is: Wherein, in formulas (4) and (5), d represents the standard deviation of line width, and h represents the standard deviation of copper thickness; The reverse line width formula in S6 is: The formula for inverse calculation of copper thickness in S6 is:

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