SMD component

Abstract

SMD component (1) with an electrical component, a component body (3) which mechanically holds the electrical component, and a plurality of connecting elements (5a, 5b) attached to the component body, wherein the SMD component (1) further comprises an alignment element (2) by means of which a mechanical bending moment (Ma, Mb) is exerted on each of the connecting elements (5a, 5b) so that exposed ends of the connecting elements (5a, 5b) are aligned coplanarly with one another with the same orientation of the bending moment, characterized in that the alignment element is formed by a component housing (2) placed on the component body (3).

Description

[0001] The present invention relates to an SMD component comprising an electrical component, a component body which mechanically supports the electrical component, and a plurality of connecting elements attached to the component body.

[0002] SMD components, also called surface-mounted devices, are generally attached to the surface of printed circuit boards using contact pins. The contact pins provide mechanical attachment of the SMD component to the circuit board. The SMD component is often also electrically connected to the circuit board via the contact pins. As an alternative to SMD construction, components can be connected to a circuit board using through-hole technology; these components are also referred to as "wire-wired components." The difference between SMD components and wire-wired components is that SMD components are soldered directly onto a circuit board using solderable contact pins, whereas wire-wired components have wire connections that are pushed through a through-hole in the circuit board.In the case of SMD components, the circuit boards conventionally have connection surfaces which are printed on the circuit board with solder paste, e.g. by means of screen or stencil printing, before being populated with SMD components and with which SMD components positioned on the top side of a circuit board are connected at least mechanically, and often also electrically, by means of a reflow process.

[0003] The high quality of electrical and / or electronic devices with SMD components depends, in addition to the quality of the circuit board and the SMD components, heavily on the flawless soldering of the SMD components to the circuit board and on the reliability of the mechanical and electrical connections between the SMD components and the circuit board. In the latter case, the reliability of the electrical connection is strongly dependent on the reliability of the mechanical connection. Inadequate mechanical fastening of a component can, for example, lead to damage to the electrical connection between the component and the circuit board, regardless of whether the mechanical fastening acts as a purely mechanical connection or also as an electrical connection.

[0004] Given the increasing miniaturization of SMD components, it is becoming increasingly difficult to provide a reliable mechanical and electrical connection between the SMD component and the printed circuit board. However, with increasing integration density and decreasing component size, controlling the quality of the electrical and mechanical connections between an SMD component and a printed circuit board also becomes more difficult, making it increasingly important to largely eliminate potential sources of error during the connection process.

[0005] From the document DE 20107150 U1, a transformer coil in SMD construction is known in which a set of several bent connection pins is provided, which are bent into a preferred horizontal position by a punching process and a molded body.

[0006] The document DE 4114391 A1 describes an SMD component with connection pins that extend downwards from the coil body and are then bent outwards again in order to attach the SMD component to the surface of a printed circuit board.

[0007] US 2010 / 0 214 758 A1 discloses a cylindrical capacitor that can be removably mounted on a circuit board. Conductor contacts extend from the capacitor in an axial direction and are then bent in a radial direction, allowing the capacitor to be attached to a circuit board using a bayonet lock.

[0008] US 2009 / 0 218 120 A1 discloses a printed circuit board and a connector comprising a housing, a protrusion received within the housing, an insertion portion provided in the housing into which the printed circuit board is inserted, and a rotating mechanism. The rotating mechanism moves a lead in the connector to a first position, where the lead is separated from the printed circuit board, and shifts the lead to a second position, where the lead is connected to the printed circuit board by soldering, when the printed circuit board is inserted into the insertion portion.

[0009] The document DE 296 23 063 U1 shows an electrical component with a housing for mounting on a printed circuit board, in which the electrical connections are led out of the housing. The housing is divided into two housing parts, which utilize a centering device for mutual guidance when joined together. The centering device is expanded into a type of locking device, which creates a secure connection between the two housing parts when the housing is closed.

[0010] DE 198 13 527 C1 discloses an SMD plastic body for components. The SMD plastic body comprises connecting elements (4) made of polygonal wire inserted into holes in a terminal block, the exposed ends of which lie in a component assembly plane. The holes are elongated relative to the cross-section of the connecting elements, with their longitudinal extension essentially perpendicular to the component assembly plane. The polygonal wire is secured in the respective elongated holes by a lateral press fit.

[0011] From the document US 5 820 387 A, a snap-on connector for attachment to a printed circuit board is known, wherein the connector comprises a strip body, connection contacts associated with the strip body for connection to a printed circuit board having an edge, and at least one fastening hook. An insertion bevel is attached to the strip body to grip the edge of the printed circuit board. The insertion bevel acts as a stop and the connector is pivoted during assembly of the printed circuit board. The insertion bevel allows the strip body to be tilted at an angle relative to the printed circuit board and the strip body to be mounted on the printed circuit board without the connection contacts coming into contact with the printed circuit board. At least one fastening element protrudes from the strip body and, when pivoted, enters a hole in the printed circuit board to secure the connector to the printed circuit board.

[0012] According to EP 0 393 599 A2, a surface-mountable, plastic-encased electrical coil is known, comprising a hollow-cylindrical coil former as the winding support and a coil former flange that can be placed on a printed circuit board, with electrical connections preferably extending laterally. The hollow-cylindrical interior of the coil former and the coil are encased on all sides, except for the electrical connections, with a plastic coating. The plastic contains a high concentration of a powdered magnetic material.

[0013] DE 84 32 252 U1 discloses a housing for accommodating display or control elements for front-mounting on printed circuit boards or the like. It consists of a roughly cuboid-shaped insulating body with connecting contacts protruding from it. The parts of the connecting contacts protruding from the housing, each with a foot at their free ends, extend out of the housing at the side. A front stop shoulder and / or a mounting pin are provided on the underside of the housing for securing the housing relative to the printed circuit board or the like.

[0014] In view of the above explanations, an SMD component according to independent claim 1 and an inductive SMD component according to independent claim 9 are provided. Advantageous embodiments of independent claim 1 are defined in dependent claims 2 to 8.

[0015] Further advantageous embodiments will become apparent from the following description of the accompanying figures, in which: Fig. 1a illustrates a cross-sectional view of an inductive SMD component according to some illustrative embodiments of the invention; Fig. 1b illustrates a cross-sectional view through a component package according to some illustrative embodiments of the invention; and Fig. 1c an enlarged view of a side wall of the component housing from Fig. 1a in an enlarged view.

[0016] Within the scope of the invention, an SMD component is generally provided with an electrical component, such as an inductive component, a capacitive component, and / or an ohmic resistance element. Inductive components can include, for example, coils, chokes, transformers, and the like, while capacitive components have capacitors. With regard to the enclosed Fig. 1a, an illustrative embodiment of the invention in the context of inductive SMD components is described below, comprising an inductive component. Regardless of the type of electrical component, it is mechanically held by a component body, to which connecting elements are connected, at least for the mechanical connection of the SMD component to a circuit board during surface mounting. The connecting elements can be designed, for example, in the form of contact pins, contact plates, and the like.

[0017] The following refers to Fig. 1a. This shows a schematic cross-sectional view of an SMD component 1. The SMD component 1 comprises a component housing 2 into which a component body 3 is accommodated. The component body 3 serves to mechanically hold an electrical component, such as, in the case shown, an inductive component which, as shown, has a magnetic core 4 with a winding (not shown). The magnetic core 4 can, for example, be designed as a double E core which is inserted in a horizontal design into the component body 3 and rests on a support surface 32 of the component body. The winding (not shown) is accommodated in a winding space 31 of the component body 3.

[0018] The component body 3 is received in a housing recess of the component housing 2, so that connecting elements 5a, 5b attached to the component body 3 partially protrude from the component housing 2. The term "partially protrude" means that contact surfaces 51a of the connecting elements 5a and contact surfaces 51b of the connecting elements 5b can be brought into at least mechanical contact with a printed circuit board (not shown).

[0019] According to the Fig. In the embodiment shown in Figure 1a, the connecting elements 5a, 5b extend into the component body 3 along a direction parallel to side walls 20a, 20b of the component housing 2 or protrude from the component body 3 along a direction parallel to the side walls 20a, 20b of the component housing 2, toward an opening in the component housing 2. The exposed ends of the connecting elements 5a, 5b are bent out of the direction of extension of the connecting elements 5a, 5b, so that the exposed ends of the connecting elements 5a, 5b extend in a direction that is not parallel to the direction of extension. Preferably, the exposed ends of the connecting elements 5a, 5b are bent perpendicular to the direction of extension.

[0020] The side walls 20a, 20b of the component housing 2 each exert a corresponding force Fa, Fb on the respective connecting elements 5a, 5b, so that the connecting elements 5a, 5b are bent out of their rest position, as can be seen from an angle α in Fig. 1a. The angle α represents a bending angle by which the connecting elements 5a in Fig. 1a are bent at the free ends with respect to their vertical position.

[0021] In particular, the force Fa exerted by the side wall 20a on the free end of the connecting element 5a generates a bending moment Ma with respect to a lever arm vector ra from the bending point Ba. The lever arm vector ra denotes a direction along the lever arm between an application point at the exposed end of the connecting element 5a and the bending point Ba, at which the connecting element 5a is bent out of the extension direction. The bending moment Ma caused by the force Fa and the lever length ra, which is exerted on the connecting elements 5a by the side wall 20a and generates a bending of the connecting elements 5a by the angle α, is shown with respect to the plane of representation in Fig. 1a is oriented vertically and directed out of the plane of representation towards the observer. A bending moment Mb, which is caused by the side wall 20b on the connecting elements 5b by means of a force Fb with respect to the lever arm vector rb, is oriented in such a way that the bending moment Mb is perpendicular to the plane of representation in Fig. 1a and is directed into the viewing plane as seen from the observer.

[0022] Regarding the representation in Fig. 1a, the above explanation is indicated by the corresponding bending moments Ma and Mb at the exposed ends of the connecting elements 5a, 5b, which are oriented out of the representation plane (cf. bending moment Ma with dot in circle) and into the representation plane (cf. bending moment Mb with cross in circle).

[0023] Due to the applied bending stress (caused by the bending moments Ma), the connecting elements 5a are aligned such that contact surfaces 51a of the connecting elements 5a are coplanar with one another. Correspondingly, contact surfaces 51b of the connecting elements 5b are coplanar with one another due to the applied bending moments Mb. It should be noted here that although the bending moments Ma can differ in their magnitude, the direction of the bending moments Ma acting on each of the connecting elements 5a is the same. Accordingly, the bending moments Mb exerted on each of the connecting elements 5b can differ in their magnitude, but are oriented in the same direction. Consequently, within the scope of the invention, connecting elements acting on bending moments of the same direction are aligned coplanar with one another.

[0024] The mechanical bending stress applied by the component housing 2 to the connecting elements 5a, 5b is constant over time given a given fixation of the component body 3 within the component housing 2 and thus prevents undesired fluttering of the connecting elements 5a, 5b, which would otherwise lead to a loose mechanical connection between the component body 3 and a printed circuit board (not shown).

[0025] In some illustrative embodiments of the invention, a positionally stable fixation of the component body 3 within the component housing 2 can be achieved, for example, by retaining ribs 21a, 21b formed in the component housing 2, which protrude from the corresponding side walls 20a, 20b within the component housing 2. Additionally or alternatively, further fixing projections 22 can be provided within the component housing 2 to determine a fixation (and optionally a penetration depth) of the component body 3 in the component housing 2.

[0026] According to some illustrative examples herein, the retaining ribs 21a, 21b may extend along the side walls 20a, 20b. Alternatively, the retaining ribs 21a, 21b may be formed only over a part of a height of the side wall 20a, 20b, as can be seen from the Fig. 1a, Fig. 1b. If the retaining ribs 21a, 21b are positioned as shown in Fig. 1a, Fig. 1b, do not extend over the entire height of the side walls 20a, 20b, a receiving area is provided for a component cover 6, which closes the opening of the component housing 2 in order to protect the electrical component accommodated in the component housing 2 from environmental influences. Additionally or alternatively, the interior of the component housing 2 can be filled with a potting compound.

[0027] It will be Fig. 1b. This schematically shows a cross-sectional view of the interior of the component housing 2, in particular an inner cross-sectional view of the side wall 20a. As can be seen from Fig. As can be seen in Figure 1b, a plurality of retaining ribs 21a and retaining elements 22a can be provided on the inner surface of the side wall 20a. Furthermore, the side wall 20a can have recesses 23 that are aligned with respect to the connecting elements 5a such that the connecting elements 5a are guided outwardly from the component housing 2 through the recesses 23. A depth of the recesses 23 can be matched to a height of the connecting elements 5a such that the contact pads 51a of the connecting elements 5a are oriented coplanar with an underside of the side wall 20a, with the side wall 20b being configured accordingly.

[0028] In Fig. Figure 1c schematically shows an enlarged section of an underside of the side wall 20b, showing a cross-sectional view of a recess 23b in the side wall 20b. Within the recess 23b, a contact surface 24b is formed, which forms an angle β with respect to an underside of the housing.

[0029] In Fig. 1b also shows optionally provided locking lugs 24 to support further fixing of the cover 6 and / or the component body 3 within the component housing 2.

[0030] Within the framework of the Fig. In the illustrative embodiments of the invention described in Figures 1a to 1c, the connecting elements 5a, 5b are applied to the component housing 2 through a lower surface of the side walls 20a, 20b of the component housing 2 under a bending stress, so that the connecting elements 5a are aligned coplanar to one another, while the connecting elements 5b are aligned coplanar to one another. According to the Fig.In the example shown in Figure 1a, the contact surfaces 51a of the connecting elements 5a are inclined to a horizontal plane at an angle α. The explicit value of the angle α does not represent a limitation of the invention, and it is evident that the angle α can be adjusted by orienting the exposed ends of the connecting elements 5a, 5b without mechanical stress and a penetration depth of the component body 3 into the component housing 2, in particular depending on the force Fa or Fb and the lever arm ra or rb. Although it may be expedient in some illustrative embodiments to select an angle α less than 0 (denotes a mathematical orientation of the angle counterclockwise), an angle α ≥ 0° can also be readily selected.

[0031] The preceding illustrative embodiments have been described in such a way that connecting elements extend along an extension direction in a component body or protrude therefrom, and exposed ends of the connecting elements extend along a direction that is not oriented parallel to the extension direction. This does not represent a limitation of the present invention. Alternatively, the connecting elements may protrude from the component body along the extension direction, wherein the extension direction may be oriented substantially parallel to a mounting surface of a printed circuit board (not shown). The term "substantially" here may include deviations of ± 45° or less.

[0032] Although the above-described embodiments are described with regard to inductive SMD components, this does not represent a limitation of the present invention. Instead of component bodies designed as coil bodies, component bodies may be provided which are intended for the mechanical mounting of capacitors and / or ohmic resistance elements or other electrical components.

Claims

[1] SMD component (1) with an electrical component, a component body (3) which mechanically supports the electrical component, and a plurality of connecting elements (5a, 5b) attached to the component body, wherein the SMD component (1) further comprises an alignment element (2) by means of which a mechanical bending moment (Ma, Mb) is exerted on each of the connecting elements (5a, 5b) so that exposed ends of the connecting elements (5a, 5b) are aligned coplanarly with one another with the same orientation of the bending moment, characterized by that the alignment element is formed by a component housing (2) placed on the component body (3). [2] SMD component (1) according to claim 1, wherein the component body (3) is a coil body and the electrical component is a coil. [3] SMD component (1) according to claim 1 or 2, wherein the component body (3) is fixed in the component housing (2) by holding ribs (21a, 21b) which protrude in the interior of the component housing (2). [4] SMD component (1) according to one of claims 1 to 3, wherein the component housing (2) has at least one contact surface (24a, 24b) to which the connecting elements (5a, 5b) are applied, so that the connecting elements (5a, 5b) are held under mechanical bending stress. [5] SMD component (1) according to claim 4, wherein the at least one contact surface (24a, 24b) is provided by at least one recess (23a, 23b) for receiving at least one connecting element (5a, 5b) for exerting the bending stress. [6] SMD component (1) according to claim 4 or 5, wherein the connecting elements (5a, 5b) protrude from the component body (3) in a rest orientation perpendicular to the extension direction in a state in which no mechanical bending stress is applied, and the mechanical bending stress causes a bend of 5° or less. [7] SMD component (1) according to one of claims 1 to 6, wherein the connecting elements (5a, 5b) extend into the component body (3) along an extension direction which is not oriented parallel to the contact plane. [8] SMD component (1) according to one of claims 1 to 7, wherein the connecting elements (5a, 5b; 35a, 35b) each have a contact surface (51a, 51b) which can be brought into contact with a printed circuit board at least mechanically, wherein all contact surfaces (51a, 51b) are arranged in a contact plane. [9] Inductive SMD component (1) with a coil former (3), a coil and a component housing (2) partially surrounding the coil former (3), wherein connecting elements (5a, 5b) protrude from the coil former (3), to which a respective bending moment is exerted by the component housing (2), so that exposed contact surfaces (51a; 51b), which are arranged at exposed ends of the connecting elements (5a, 5b) and are to be brought into contact with a printed circuit board at least mechanically, are aligned coplanar to one another with the same orientation of the bending moments.

Images