SMD inductor component with a predetermined coplanarity

Abstract

Inductor component (100) in SMD package for low-frequency magnetic fields, comprising a housing (102) with a housing base (104) for mounting on a printed circuit board, three windings arranged within the housing (102), in particular essentially orthogonal to each other, along an X, Y and Z winding axis, and Connection contacts (110) arranged on the base surface (104) in a pad layout (108), wherein the dimensions of the housing base (104) and the dimensions of the connection contacts (110) provide a flat design profile with a predetermined coplanarity of the connection contacts (110), preferably with a coplanarity of at most 0.10 mm for an AOI-optimized design and at most 0.15 mm for a standard design.

Description

[0001] The invention relates to an inductor component in SMD design for low-frequency magnetic fields, in particular for applications of contactless identification and / or near-field communication.

[0002] In the prior art, multi-axis inductor components are used, whose windings are arranged in a housing and connected to a printed circuit board via connection contacts located on the housing base. Marking features are commonly used for assembly and orientation, and geometric specifications, including aspect ratios of the housing base, position and size of the connection contacts, minimum distances in the pad layout, and limit values ​​for the flatness of the contact surfaces (coplanarity), are used for manufacturing and testing processes.

[0003] The assignment of winding ends to connection contacts, internal electrical connections between selected pins, and the corresponding test and measurement access points are often manufacturer-specific and differ between package types. Similarly, the geometric designs vary with regard to contact arrangement along the edges, contact grouping, and dimensional tolerances, which complicates the transferability of printed circuit board layouts and the standardization of assembly, inspection, and testing procedures.

[0004] It is an object of the invention to specify an inductor component in which the design of the pin configuration and / or the dimensions, including geometric specifications of the housing base area and the pad layout, are standardized and specified.

[0005] Accordingly, an SMD-mounted inductor component for low-frequency magnetic fields is proposed, comprising a housing with a base area for mounting on a printed circuit board, three windings arranged within the housing, in particular substantially orthogonal to each other, along an X, Y and Z winding axis, and connection contacts arranged on the base area in a pad layout, wherein the dimensions of the base area and the dimensions of the connection contacts provide a flat profile with a predetermined coplanarity of the connection contacts, preferably with a coplanarity of at most 0.10 mm for an AOI-optimized design and at most 0.15 mm for a standard design.

[0006] The inductor component can be manufactured in SMD form factor and have a housing footprint for mounting on a printed circuit board. This facilitates machine placement and supports standardized assembly. SMD preferably refers to a surface mount component where the component is placed directly onto solder pads on the printed circuit board.

[0007] The windings can be arranged within the housing and run along X, Y, and Z winding axes. In particular, the winding axes can be substantially orthogonal to each other (i.e., ± 20% deviation from a normal). This enables direction-independent magnetic detection. The winding axis preferably denotes the main geometric axis of the respective coil, along which the field coupling is maximal.

[0008] The connection contacts can be arranged on the housing base in a pad layout. For example, the contacts can be numbered and positioned along the edges. This organizes the circuit board layout and makes test connections clearly identifiable.

[0009] The dimensions of the housing base and the connection contacts can provide a flat profile with a predetermined coplanarity of the connection contacts. Preferably, the coplanarity is at most 0.10 mm for an AOI-optimized design and at most 0.15 mm for a standard design. This improves solder wettability and stabilizes quality in reflow processes. Coplanarity preferably refers to the maximum flatness deviation of the contact surfaces relative to the reference plane of the housing base.

[0010] In a preferred embodiment, it is proposed that the housing base be rectangular. Preferably, the side lengths can be proportionate for practical use. This ensures efficient use of space on the printed circuit board.

[0011] The practical ratio can be understood as a dimensionally related ratio between two or more parameters, based on established design and manufacturing guidelines and reliably achievable in series production. In particular, such a ratio can refer to the side lengths of a component footprint, ensuring proportions that support efficient placement on the printed circuit board, clear pad arrangement, and safe handling. Preferably, the ratio lies within a range compatible with standard DRC rules, assembly tolerances, and reflow process windows, without requiring special measures. For example, rectangular footprints with moderate proportions can be selected, promoting both the mechanical stability of the component and the electrical separation of the contact groups.This enables consistent layout planning, improves the use of building space and facilitates the interchangeability between layout variants.

[0012] The pad layout can include connection contacts arranged along the edges of the housing base. For example, corner pads and intermediate side pads can be provided. This increases mechanical stability during soldering and supports the electrical isolation of the contact groups.

[0013] The corner pad preferably refers to a solder connection positioned at a corner of the housing base, while the side pad preferably describes a solder connection located on an edge between two corners. This makes the contact distribution unambiguous and simplifies stencil production.

[0014] In a preferred embodiment, it is proposed that the coplanarity of the connection contacts relative to the housing base area can be specified by a limit value. Preferably, the specification can be documented in a dimensional tolerance table. This makes the manufacturing inspection clear and reproducible.

[0015] The housing footprint, overall height, and coplanarity can be defined in a common dimensional tolerance table. For example, standard tolerances can be used. This increases interchangeability between production batches.

[0016] Overall height preferably refers to the maximum height of the housing perpendicular to the housing base. A dimensional tolerance table preferably refers to a structured specification of permissible deviations for defined dimensions. This makes quality control clearer and documentation consistent.

[0017] In a preferred embodiment, it is proposed that a ratio of the side lengths of the housing base is specified within a predetermined range and that the overall height is specified as being smaller than one of the side lengths of the housing base, preferably with a weight in the gram range, particularly preferably from 1 to 1.5 grams.

[0018] The side lengths of the housing base can be defined in a predetermined ratio. Preferably, this ratio lies within a practical range that facilitates printed circuit board placement. This simplifies layout planning and ensures consistent allocation of installation space. Side length preferably refers to the outer edge of the housing base along a principal axis of the component.

[0019] The practical range can be understood as a value interval that is based on established standards, typical manufacturing capabilities, and common layout guidelines, and can be reliably maintained under real-world production conditions. In particular, this range can be aligned with manufacturing tolerances, ensuring that common SMT processes such as paste printing, placement, reflow, and AOI run stably without special approvals. Preferably, design rules are considered that are compatible with common DRC limits for pad spacing, solder pads, and trace widths. Furthermore, the range can adhere to mechanical and handling-related limits that support standard grippers, trays, and tape packaging. For example, the electrical function is dimensioned so that coplanarity, contact areas, and contact spacing guarantee the intended connection and measurement functionality.Preferably, the specifications are based on general tolerance standards such as DIN ISO 2768 as well as internal factory standards. This enables implementation without atypical special measures and ensures consistent quality across different production batches.

[0020] The overall height can be defined as less than one of the side lengths of the housing base. This allows for a particularly low profile. This ensures compliance with the clearance height in placement and AOI systems and favorably positions the component's center of gravity. Overall height preferably refers to the maximum height perpendicular to the housing base.

[0021] The weight can be specified in the gram range. For example, the range is 1 to 1.5 grams. This allows the gripper and conveyor technology to be adapted to common SMD processes and reduces the mechanical stress on the solder joints. Weight preferably refers to the mass of the complete component, including the housing and leads.

[0022] In a preferred embodiment, it is proposed that minimum distances between adjacent connection contacts can be specified in the pad layout. These distances are preferably based on applicable solder paste and DRC guidelines. This reduces the formation of unwanted solder bridges and improves inspectionability. The minimum distance preferably refers to the smallest permissible distance between the edges of two solder pads.

[0023] Minimum contact areas of the connection contacts on the housing base can be specified. For example, areas are selected to ensure stable wetting. This improves the mechanical holding force of the solder joint and stabilizes the electrical contact quality. The contact area preferably refers to the projected solder area of ​​a connection contact onto the printed circuit board plane.

[0024] In a preferred embodiment, it is proposed that a marking feature for identifying a reference terminal contact can be provided on the housing base. Preferably, a dot marking is used that is uniquely assigned to a predetermined pin. This ensures unambiguous orientation during assembly and testing, and avoids confusion. The marking feature preferably refers to a visible mark on the housing that indicates a reference position.

[0025] The arrangement of the connection contacts can define a unique orientation of the inductor component on the printed circuit board. In particular, the position and shape of the pads support consistent pick-and-place behavior. This increases process stability and makes AOI detection more reliable. Orientation preferably refers to the defined alignment of the component relative to the printed circuit board coordinate system.

[0026] The dot marking can be understood as a visible, small-area marker on the housing base or on the housing itself, which can uniquely identify a reference position and a specific connection contact. Preferably, it is a printed or embossed dot that corresponds to a predetermined pin, for example, pin 1. In particular, the dot marking can be in a contrasting color so that it is easily recognizable during visual inspection and assembly. This ensures the unambiguous orientation of the component on the printed circuit board and prevents confusion.

[0027] In a preferred embodiment, it is proposed that the position of the connection contacts on the housing base can correspond to the winding axes within the housing. Preferably, the assignment is such that each winding axis has its own contact group. This ensures clear electrical separation of the strands and improves measurability per axis. A contact group preferably refers to a set of connection contacts that are assigned to a common winding end or a common winding axis.

[0028] In particular, contact groups can be assigned to individual winding axes. For example, each axis can be addressed by a pair of terminals. This simplifies troubleshooting and makes the testing steps more structured. Winding axis preferably refers to the direction of maximum magnetic coupling of the respective coil.

[0029] In a preferred embodiment, it is proposed that the dimensions of the pad layout can take into account aperture specifications for a solder paste stencil. Preferably, aperture sizes and shapes are selected to create defined solder deposits. This results in more uniform wetting and more reproducible solder joints. A solder paste stencil preferably refers to a metal foil with cutouts through which solder paste is applied to the printed circuit board.

[0030] In particular, the pad layout can be specified for reflow soldering processes. For example, pad geometries and spacing are adapted to common reflow profiles. This increases process stability in the oven and reduces component misalignment. Reflow soldering preferably refers to a thermal process in which previously printed solder paste is melted to create permanent connections.

[0031] In a preferred embodiment, it is proposed that the housing base be rectangular. In particular, the connection contacts can be arranged along the edges of this base. This results in clear PCB layout and standardized placement. "Rectangular" preferably refers to a square base shape with two pairs of edges of equal length.

[0032] The arrangement of the connection contacts along the edges can be designed such that the contact groups of the X, Y, and Z windings are spatially separated from one another. Preferably, distances between the groups are defined for this purpose. This reduces the tendency for electrical crosstalk and makes the assignment during testing more unambiguous. A contact group preferably refers to a defined set of pads that are assigned to a winding axis.

[0033] In a preferred embodiment, it is proposed that the inductor component can be configured for operation at an excitation frequency of 125 kHz. For example, the internal assignments of the winding ends to the connection contacts are adjusted accordingly. This increases functional reliability in LF RFID environments and ensures consistent measurability.

[0034] In particular, an operating temperature range of -40 °C to +85 °C can be provided. Preferably, the material selection and housing design are adapted to this range. This ensures reliability under typical automotive and industrial conditions. Operating temperature range preferably refers to the permissible temperature span within which specified properties are maintained.

[0035] In particular, the rectangular housing footprint can be referenced with a defined longitudinal axis and a transverse axis. Preferably, the assignment of the contact groups to these axes is defined. This ensures a uniform orientation in CAD libraries and facilitates the reuse of footprints.

[0036] The contact groups can be arranged in a defined sequence along the edge. For example, a sequence can be defined according to the winding axes (X group, Y group, Z group). This reduces the risk of confusion during manual and automated testing.

[0037] Each contact group can comprise a minimum number of pads. Preferably, an identical number of pads is provided for each winding axis. This maintains symmetry and improves consistency during assembly.

[0038] The corner pads can be designed as mechanical support points. In particular, a larger projected soldering area can be provided for corner pads than for side pads. This increases the shear strength of the solder joints and reduces the tilting moment of the component.

[0039] The pad edges can be designed with defined curves or chamfers. Preferably, the aperture contours of the solder paste stencil are adapted to this shape. This makes the solder paste application more reproducible and reduces the risk of tombstoning.

[0040] The reference plane for coplanarity can be uniquely defined as the plane of the housing base. For example, a measurement method with three-point support is described. This improves the comparability of measurements between production batches.

[0041] The aspect ratio of the housing base can be adapted to standardized tape widths and pocket dimensions. Preferably, the position of the reference pin relative to the tape direction is fixed. This speeds up feeder setup and reduces the frequency of incorrect insertions.

[0042] The dot marker can have a minimum size and / or minimum contrast. In particular, a color space and / or a tolerance range for the position can be defined. This ensures stable detectability in AOI systems and reduces the false error rate.

[0043] The contact distances between different contact groups can be specified larger than the distances within a contact group. Preferably, a two-stage distance regime is created. This makes the assignment during optical inspection more intuitive and improves electrical decoupling.

[0044] The pad orientation can be aligned to a standardized zero-degree position. For example, the longitudinal axis of the housing base is defined as 0° and all pad longitudinal sides are aligned parallel to it. This increases the consistency between EDA libraries and manufacturing data.

[0045] The coplanarity limits can be differentiated depending on the pad position. Preferably, stricter values ​​apply to corner pads than to side pads. This improves stability during the reflow phase.

[0046] The assignment of winding axes to contact groups can be combined with a reserved, unpopulated reference area on the housing base. This area serves as a visual anchor during inspection. This makes the axis assignment visually verifiable and reduces training requirements.

[0047] The pad metallization can have defined surface roughness and / or specific finish specifications. Preferably, a finish compatible with common SAC alloys is chosen. This results in more stable wetting and reduces rework.

[0048] The printed circuit board apertures can be designed as split openings. For example, two smaller apertures per pad are specified. This facilitates outgassing during reflow and reduces void formation.

[0049] Temperature and frequency data can be linked to test conditions. Preferably, measuring points and tolerance windows are defined for series production release. This increases the comparability of test reports and reduces the effort required for handling complaints.

[0050] The rectangular base can be supplemented with defined keep-out zones at the edges.

[0051] In particular, no further conductor tracks are routed there. This results in a more even distribution of the solder paste and reduces capillary effects.

[0052] The contact groups can carry a defined internal code. For example, a laser engraving with axis identification is provided. This simplifies manual assignment in the laboratory and reduces documentation errors.

[0053] The component position can be secured against rotation. Preferably, an asymmetrical combination of dot marking and housing edge feature is used. This practically eliminates 180° rotation during component placement.

[0054] Setting a minimum aspect ratio can improve the stability of thin packages. For example, a ratio is chosen that limits flex during reflow soldering. This helps maintain coplanarity after the soldering process.

[0055] The combination of a fixed temperature range and predetermined coplanarity can serve as a common release criterion. Preferably, an incoming goods inspection with a sampling plan is defined. This ensures consistent series quality and allows deviations to be detected early.

[0056] The following section explains embodiments, further developments, and examples of the invention in more detail with reference to the accompanying drawings. The figures show: Fig. Figure 1 shows an inductor component in SMD design in a top view with a housing; Fig. Figure 2 shows an SMD inductor component in a top view of the housing base without a housing cover; and Fig. Figure 3 shows a winding configuration for the X, Y, and Z winding axes.

[0057] Identical features are identified by the same reference numerals in the figures. The invention is further explained with reference to the two figures.

[0058] Fig. Figure 1 shows an inductor component 100 in SMD package with a housing 102 and a housing base 104 for mounting on a printed circuit board (not shown). A dot marking 106 is shown on a top side of the housing 102, which can identify a reference terminal contact. The housing base 104 can be essentially rectangular and have a pad layout 108 with several terminal contacts 110 (consecutively also labeled 1-8) along its edges. Corner pads 112 can be arranged in the four corners; side pads 114 can be placed between them (see Figure 1). Fig. 2) be provided for.

[0059] The position of the connection contacts 110 can be selected such that contact groups 116, 118, and 120 are each assigned to an X, Y, or Z winding axis, respectively. Contact group 116, assigned to the winding of the X winding axis, can comprise connection contacts 2, 3, 6, and 7. Contact group 118, assigned to the winding of the Y winding axis, can comprise connection contacts 1 and 5. Contact group 120, assigned to the winding of the Z winding axis, can comprise connection contacts 4 and 8. The dimensions of the housing base 104 and the connection contacts 110 can be configured for a low-profile design and a predetermined coplanarity of the connection contacts. Optionally, a coplanarity of no more than 0.10 mm is provided for an AOI-optimized version and no more than 0.15 mm for a standard version.

[0060] The marking 106 can be in a contrasting color and can serve for clear orientation during assembly and testing. The housing contour is shown with rounded corners. The side lengths of the rectangular housing base 104 can form a practical ratio, and the overall height of the housing can be less than one of the side lengths of the housing base. A type and date marking 122 can also be present on the top surface, which can support traceability.

[0061] Minimum distances may be provided between contact groups 116, 118, and 120 to clarify the spatial separation of the groups.

[0062] Fig. Figure 2 shows the pad layout 108 of the inductor component 100 in a top view of the housing base 104 without the housing 102 or housing cover, showing the rectangular base shape and the connection contacts 110 arranged along the edges. The corner pads 112 with a larger projected soldering area, which can serve as mechanical support points, are shown in the four corners. Side pads 114 can be arranged along each of the sides.

[0063] The contact groups 116, 118, and 120 can be assigned to the winding axes X, Y, and Z and be spatially separated from one another. Minimum contact contact cross-sectional areas can be provided within the contact groups, and minimum distances can be maintained between adjacent contacts to facilitate the reflow process and AOI inspection. The arrangement along the edges can be chosen to ensure a clear orientation relative to a longitudinal axis 124 and a transverse axis 126 of the housing base 104. The pad layout dimensions can accommodate aperture specifications for a solder paste stencil, potentially including split or adapted aperture geometries.

[0064] The coplanarity of the connection contacts preferably refers to the plane of the housing base 104. The layout can facilitate the assignment of winding ends to the connection contacts, so that each winding axis can be electrically connected via its respective contact group. The spatial separation of the contact groups 116, 118, 120 reduces crosstalk and facilitates measurement access per axis. The rectangular housing base can be designed with an aspect ratio that allows for efficient placement in the printed circuit board design, and the overall height (not shown) is specified in a dimensional tolerance table along with coplanarity and base dimensions. For operation, the inductor component can be configured for an excitation frequency of 125 kHz and an operating temperature range of -40 °C to +85 °C.

[0065] Out of Fig. Figure 3 again highlights contact groups 116, 118, and 120 with regard to the winding configuration and the X, Y, and Z winding axes, respectively. According to the top view, contact group 116 (X winding) can be located on the right edge of the housing and includes pins 2 / 3 and 6 / 7. In the electrical diagram, Lx can be routed between the short-connected pins 2-3 (left winding end Lx) and the short-connected pins 6-7 (right winding end Lx). This connects the X axis via two internally bridged pairs of terminals. In the layout diagram, the corresponding pads 2 / 3 can be located at the top right and 6 / 7 at the bottom right. The vertical arrangement along the same edge clarifies the group affiliation and facilitates unambiguous contacting of the X winding.

[0066] Contact group 118 (Y-winding) can be assigned to pins 1 and 5. In the circuit diagram, Ly can be connected between pin 1 (left winding end Ly) and pin 5 (right winding end Ly), particularly without an internal short circuit. In the top view, pin 1 can be positioned in the upper right (directly next to 2) and pin 5 in the lower left. The diagonal position of these two pads can represent the Y-group and can spatially separate it from the X- and Z-winding groups. At the same time, the assignment can remain unambiguous via the pin numbers and the diagram labels.

[0067] Contact group 120 (Z-winding) can be assigned to pins 4 and 8. In the circuit diagram, Lz can be routed between pin 4 (left winding end Lz) and pin 8 (right winding end Lz), preferably also without an internal short circuit. In the top view, pin 4 can be located in the upper left and pin 8 in the lower right. This diagonally opposite arrangement can identify the Z-group and create distance from the other groups, which supports electrical decoupling and keeps test accesses per axis clear.

[0068] This connects the X-winding via the edge pairs (2 / 3) and (6 / 7) on the right, the Y-winding via individual pins 1 (top right) and 5 (bottom left), and the Z-winding via individual pins 4 (top left) and 8 (bottom right). The short connections 2-3 and 6-7 shown in the circuit diagram are mirrored in the layout according to... Fig.The two adjacent double pads on the right edge are used, while the Y and Z windings are connected diagonally via two single pads each. This makes the axis assignment visually comprehensible, the contact groups are spatially separated, and the measurement and placement logic remains consistent between the circuit diagram and pad layout. REFERENCE MARK LIST 100 inductor components 102 cases 104 Housing footprint 106 Point marking 108 Pad Layout 110 Connection contact 112 Corner pad 114 side pad 116 Contact group X-winding (pins 2 / 3, 6 / 7) 118 Contact group Y-winding (pins 1, 5) 120 Contact group Z-winding (pins 4, 8) 122 Type / date marking 124 Longitudinal axis of the housing base 126 Transverse axis of the housing base 130 Interconnection / Short bandage Pins 2-3 132 Interconnection / Short bandage Pins 6-7

Claims

[1] SMD inductor component (100) for low-frequency magnetic fields, comprising a housing (102) with a housing base (104) for mounting on a printed circuit board, three windings arranged within the housing (102), in particular essentially orthogonal to each other, along an X, Y and Z winding axis, and Connection contacts (110) arranged on the base of the housing (104) in a pad layout (108), wherein the dimensions of the housing base (104) and the dimensions of the connection contacts (110) provide a flat design profile with a predetermined coplanarity of the connection contacts (110), preferably with a coplanarity of at most 0.10 mm for an AOI-optimized design and at most 0.15 mm for a standard design. [2] Inductor component according to paragraph 1, wherein the housing base (104) is rectangular and the pad layout (108) comprises connection contacts (110) arranged at the edges of the housing base (104), preferably with corner pads (112) and intermediate side pads (114). [3] Inductor component according to one of the preceding digits, wherein the coplanarity of the terminal contacts (110) relative to the housing base area (104) is specified by a limit value and the housing base area (104), the overall height of the housing (102) and the coplanarity are specified in a dimensional tolerance table. [4] Inductor component according to one of the preceding digits, wherein a ratio of the side lengths of the housing base (104) is specified within a predetermined range and the overall height of the housing (102) is specified as being smaller than one of the side lengths of the housing base (104), preferably with a weight in the gram range, particularly preferably from 1 to 1.5 grams. [5] Inductor component according to one of the preceding digits, wherein minimum distances between adjacent terminal contacts (110) and minimum cross-sectional areas of the terminal contacts (110) on the housing base surface (104) are specified in the pad layout (108). [6] Inductor component according to one of the preceding digits, wherein a marking feature (106) for identifying a reference terminal contact is provided on the housing base (104) and the arrangement of the terminal contacts (110) determines a unique orientation of the inductor component (100) on the printed circuit board, preferably with a dot marking (106) for identifying a predetermined pin. [7] Inductor component according to one of the preceding numbers, wherein the position of the connection contacts (110) on the housing base (104) corresponds to the winding axes inside the housing (102) and contact groups (116, 118, 120) are assigned to individual winding axes. [8] Inductor component according to one of the preceding digits, wherein the dimensions of the pad layout (108) take into account aperture specifications for a solder paste stencil and are specified for reflow soldering processes. [9] Inductor component according to one of the preceding digits, wherein the housing base (104) is rectangular and the arrangement of the terminal contacts (110) is carried out along the edges, wherein the contact groups (116, 118, 120) of the X, Y and Z windings are spatially separated from each other. [10] Inductor component according to any of the preceding digits, wherein the inductor component (100) is configured for operation at an excitation frequency of 125 kHz and an operating temperature range of -40 °C to +85 °C.

Images