GB2541546A

GB2541546A - SMD device

Info

Publication number: GB2541546A
Application number: GB1613564.2A
Authority: GB
Inventors: Boldl Johann; Pilsl Rainer
Original assignee: Sumida Components and Modules GmbH
Current assignee: Sumida Components and Modules GmbH
Priority date: 2015-08-10
Filing date: 2016-08-08
Publication date: 2017-02-22
Anticipated expiration: 2036-08-08
Also published as: FR3040118B1; GB2541546B; FR3040118A1; DE102015215205A1; DE102015215205B4

Abstract

An SMD device comprises an electronic component such as an inductor, a carrier 10 holding the electronic component and a plurality of U-shaped solder pins 12a, 12b. The solder pins are attached to the carrier and each have a first contact end 14a, 14b to be soldered to a circuit board and a second contact end 16a, 16b connected to a connecting wire of the electronic component. The first contact ends are arranged on at least one side of the carrier in a first row, and a second row consisting of the second contact ends is defined above said first row on the corresponding side of the carrier. In a top view direction perpendicular to a direction of extension of the first and/or second row, at least some of the solder pins have the respective first contact ends displaced by a displacement distance (Vc, Vb, Fig 2b) relative to the respective second contact ends along said direction of extension. This allows easier inspection of the solder joint. The pins may have an offsetting portion (7b, Fig 1), or may simply be mounted at an angle (see Fig 3b).

Description

SMD Device

The present invention relates to a surface mounted device (SMD), in particular an inductive component of the SMD type for fixing to a circuit board by means of at least one solder pin.

In contrast to through-contacting techniques, where connecting wires of electronic components are passed through placement holes in a circuit board and soldered on the back of the circuit board (or via inner layers), SMD devices are fixed directly to a circuit board via solderable contact terminals. This technique is frequently also referred to as surface mounting, which, in comparison with through-contacting, allows a very dense population, since e.g. circuit boards can be populated on both sides in surface mounting processes. Conventional plastic bodies for SMD devices are known e.g. from the publications DE 101 14 182 A1 and DE 198 13 527 C1.

With the increasing scaling to smaller components, surface mounting is preferably carried out by machines, since precise manual positioning of the components is here no longer possible with necessary accuracy. Properly functioning circuits require a perfect solder connection and, to this end, test procedures are used for examining the quality of a solder connection. This can be done e.g. in the course of an automated optical inspection (AOI), where industrial image processing equipment is increasingly used for inspecting solder joints, so as to inspect the quality of a machine-made solder connection with high speed and precision.

However, it turned out that the optical inspection of circuit boards with high integration densities requires strongly increasing efforts and that it will here be necessary to use modern imaging methods for maintaining the reliability of the AOI in spite of increasing integration densities on a circuit board.

Taking as a basis the above described situation, it is therefore desirable to provide a solder pin for an SMD device and an SMD device, in the case of which, in spite of advanced miniaturization, an optical inspection of the solder connections between a circuit board and the SMD device can be carried out with high precision and short inspection times.

According to one aspect of the present invention, an SMD device is provided, which comprises an electronic component, a carrier holding the electronic component and a plurality of U-shaped solder pins, which are attached to the carrier. The solder pins each have a first contact end to be soldered to a circuit board and a second contact end connected to a connecting wire of the electronic component. At least one side of the carrier has arranged thereon the first contact ends in a first row, a second row, which consists of the second contact ends, being defined above said first row on the corresponding side of the carrier. In a top view direction perpendicular to a direction of extension of the first and/or second row, at least some of the solder pins have the respective first contact ends displaced by a displacement distance relative to the respective second contact ends along said direction of extension. Thus, it is achieved that the contact ends of the solder pins are clearly visible in an optical solder pin inspection and that especially the view of the first row of contact ends (in particular of the first contact ends) is not blocked by the second row of contact ends.

According to an illustrative embodiment, the displacement distance lies in a range of 0.3 mm to 2 mm, preferably in a range of 0.3 mm to 1 mm.

According to a further illustrative embodiment, the first contact end and the second contact end of each solder pin are connected by a connecting portion extending, at least partially, in the carrier, the connecting portion comprising at least one connecting sub-portion extending along the top view direction and a connecting sub-portion extending parallel to the direction of extension of the first and/or second row.

According to an alternative embodiment, the first contact end and the second contact end of each solder pin are connected by a connecting portion extending, at least partially, in the carrier, the connecting portion extending in the carrier at an angle having a magnitude between 0° and 90° relative to the direction of extension of the first and/or second row.

According to another illustrative embodiment, the electronic component is configured as an inductive component comprising a winding connected to the second contact ends of two solder pins. Alternatively, the inductive component may have a plurality of windings, which are each connected to second contact ends.

According to the above described aspect, the contact ends are advantageously prevented from being positioned directly above one another in a view along a direction parallel to the connecting portion and perpendicular to a direction along which the elongate contact ends extend. It is achieved that, when the solder pin is used in an SMD device, the first elongate contact end of the solder pin is clearly visible during an optical solder pin inspection and that, in particular, the view of the first elongate contact end is not blocked by the second elongate contact end, when the solder pin is installed in an SMD device such that the connecting portion is oriented perpendicular to a base of the SMD device (the term “base” refers here to the SMD device surface, which, when an SMD device is surface mounted on a circuit board, will be directed towards a surface of the circuit board).

In the following, the present invention will be described making reference to the figures enclosed, in which:

Fig. 1 shows a schematic perspective view of a solder pin according to some illustrative embodiments of the invention;

Fig. 2a and 2b show different views of a carrier for an SMD device according to some illustrative embodiments of the invention; and

Fig. 3a and 3b show an enlarged side view of a carrier according to various illustrative embodiments of the invention.

Making reference to Fig. 1, illustrative embodiments of the present invention are now described with respect to a solder pin.

Fig. 1 shows schematically a perspective view of a solder pin 1, which represents a U-shaped solder pin and which is adapted for use in a carrier of an SMD device for electrically connecting an SMD component to a circuit board, said SMD component being held by the carrier. The solder pin 1 comprises a first straight elongate contact end 3 and a second straight elongate contact end 5. The first contact end 3 and the second contact end 5 extend substantially in the same direction and are substantially parallel to one another. The term "substantially" means that a direction of extension of the first contact end 3 and a direction of extension of the second contact end 5 define a maximum angle of 30° or a maximum angle of 20° or a maximum angle of 15° or a maximum angle of 10° or a maximum angle of 5° relative to one another.

According to an illustrative embodiment, the contact ends 3, 5 are represented by the end areas of a conductive wire bent into the shape of a solder pin, an electrical contact between the solder pin and the SMD component (not shown) and the circuit board (not shown), respectively, being established at said contact ends in SMD applications. In the case of some illustrative applications of the solder pin 1 in SMD devices (not shown), the contact end 3 is provided e.g. for soldering to a circuit board (not shown). In addition, the second contact end 5 is used for establishing a mechanical or an electromechanical connection between the solder pin 1 and an electronic component (not shown) of an SMD device (not shown). Illustrative examples of an SMD device will be described hereinbelow making reference to Fig. 2a, 2b, 3a and 3b.

The first contact end 3 and the second contact end 5 of the solder pin 1 are connected mechanically and in an electrically conductive manner by a connecting portion 7. According to the exemplary representation shown in Fig. 1, the connecting portion 7 comprises a first connecting sub-portion 7a and a second connecting sub-portion 7b, the first connecting sub-portion 7a and the second connecting sub-portion 7b being, at least sectionwise, oriented transversely to a direction along which the elongate contact ends 3, 5 extend. In the example shown, the connecting sub-portions 7a and 7b are, at least sectionwise, oriented such that they are orthogonal to each other. This is not meant in a limiting sense and, alternatively, the connecting sub-portion 7a may, at least sectionwise, be oriented such that it is skew relative to the connecting sub-portion 7b.

According to the embodiment shown in Fig. 1, the first connecting sub-portion 7a defines together with the first contact end 3 a U-shaped configuration, since a lower elongate subsection 7a1 of the first connecting sub-portion 7a extends perpendicular to the contact ends 3, 5 and since an upper elongate subsection 7a1 of the connecting sub-portion 7a extends parallel to the direction of extension of the contact end 3. Furthermore, the second contact end 5 and the second connecting sub-portion 7b define an L-shaped portion of the solder pin 1 according to the representation shown in Fig. 1. This is not meant in a limiting sense and the connecting sub-portion 7b may also directly follow the lower subsection 7a1 without the upper subsection 7a1 being provided.

According to the embodiment shown in Fig. 1, a plane defined by the first contact end 3 and the first connecting sub-portion 7a and a plane defined by the second contact end 5 and the second connecting sub-portion 7b are oriented such that they are not parallel to one another. According to the representation shown, the plane defined by the first contact end 3 and the first connecting sub-portion 7a may be perpendicular to the plane defined by the second contact end 5 and the second connecting subportion 7b.

For the purpose of illustration, a three-dimensional coordinate system xyz is depicted in Fig. 1. With respect to the depicted coordinate system xyz, the first and second contact ends 3, 5 may, e.g., extend along the x-direction, whereas the connecting sub-portion 7a comprises at least one sub-portion (cf. subsection 7a1) which extends, at least partially, along the z-direction, and optionally a further sub-portion (cf. subsection 7a1) which extends along the y-direction of the xyz system.

According to an exemplary embodiment, the solder pin 1 is configured such that the second contact end 5 is arranged outside of a plane defined by the first contact end 3 and the substantially U-shaped configuration of the solder pin 1. With respect to Fig. 1, a plane may e.g. be defined by the first contact end 3 and the first connecting subportion 7a, the second contact end 5 being here arranged outside of this plane.

As can be seen from Fig. 1, a displacement V between the first contact end 3 and the second contact end 5 is therefore provided, with displacement components along the y-direction (cf. displacement component Vy) and the z-direction (cf. displacement component Vz). Conventional U-shaped solder pins (i.e. solder pins having a planar U-shape), however, only have one displacement distance with one displacement component, e.g. only in the z-direction, since the contact ends define here a plane with the connecting portion and the contact ends are arranged in displaced relationship with one another in said plane.

This means that a plane defined by the contact ends 3, 5, as indicated e.g. in Fig. 1 by a plane section E with normal vector n, is therefore, at least sectionwise, oriented obliquely to at least one connecting sub-portion 7a, 7b, so that the at least one connecting sub-portion 7a, 7b extends, at least sectionwise, non-parallel to the plane (cf. plane section E in Fig. 1) and non-perpendicular to the normal vector n. As regards the representation in Fig. 1, the plane section E is oriented at an angle a to the z-direction, the following holding true for the magnitude of the angle | a |: 0 < | a| < 90°. According to some exemplary embodiments, the following may hold true: 5° < | a | < 30°.

According to some exemplary embodiments, a length of the connecting sub-portion 7a is larger than a length of the connecting sub-portion 7b. According to some explicit examples, a length of the lower subsection 7a1 may in this context be larger than a length of the connecting sub-portion 7b. In a view of the solder pin 1 along a direction parallel to the subsection 7a1, the displacement Vy between the contact ends 3, 5 can be seen and the contact ends 3 and 5 can easily be optically distinguished. Furthermore, the displacement Vz is larger than the displacement Vy. In particular, the displacement Vy is determined by the connecting sub-portion 7b, whereas the displacement Vz is defined by the lower subsection 7a1.

Fig. 2a schematically shows, in a perspective view, a carrier 10 for an inductive component (not shown), e.g. a transformer or an inductor. The carrier 10 holds here a magnetic core (not shown) and a winding (not shown). Connecting wires of the winding (not shown) are to be connected to U-shaped solder pins from a plurality of U-shaped solder pins, e.g. to at least one U-shaped solder pin of a first plurality of U-shaped solder pins 12a arranged on a first side of the carrier 10, and to at least one U-shaped solder pin of a second plurality of U-shaped solder pins 12b arranged on a second side of the carrier 10, said first and second sides representing opposed sides of the carrier 10. When a circuit board (not shown) is being populated, a lower surface U of the carrier is connected to a circuit board (not shown). This may be done e.g. by soldering first contact ends 14a, 14b of the plurality of solder pins 12a, 12b.

Fig. 2b schematically shows a view of the lower surface U of the carrier 10 according to Fig. 2a. As can be seen from the view according to Fig. 2b, the first contact ends 14a, 14b are arranged in displaced relationship with second contact ends 16a, 16b of each solder pin of the plurality of solder pins 12a, 12b. This means that the first and second contact ends 14b, 16b of each solder pin are arranged such that, in a direction perpendicular to the viewing direction in Fig. 2b, they are displaced by a displacement distance Vb. Correspondingly, the first and second contact ends 14a, 16a are arranged such that they are displaced relative to one another by a displacement distance Vc. This allows a good visibility of the first and second contact ends 14b, 16b and 14a, 16a in the case of an optical inspection of the solder pins, and in particular the first contact end 14b and 14a will not be covered by the second contact end 16b and 16a. In other words, a plane defined by the contact ends 14b, 16b and 14a, 16a of a solder pin intersects the sectional plane shown in Fig. 2b at an angle having a magnitude between 0 and 90°.

In order to improve the insulation strength and the creep resistance, the lower surface U of the carrier 10 may additionally have formed thereon projections 17, which have grooves defined between them, so that the creep resistance and the insulation strength between neighboring solder pins can be increased in an advantageous manner.

Fig. 3a and 3b each show a schematic, enlarged view of one side of the carrier 10 in Fig. 2a.

The side view shown in Fig. 3a is oriented perpendicular to a top view direction A, the view of the lower surface U in Fig. 2b being shown parallel to said top view direction A. According to the exemplary embodiment shown in Fig. 3a, contact ends 14a of the solder pin of the first plurality of solder pins 12a on the first side in Fig. 2a are arranged in a first plane E1, so that the first plane E1 extends along a first direction R1, which is oriented perpendicular to the top view A. Due to the arrangement in the first plane, the contact ends 14a are arranged in a first row.

Furthermore, the second contact ends 16a are arranged on the first side such that they define a second plane E2, which extends along a second direction R2. Accordingly, the second contact ends 16a are arranged in a second row, which is arranged above the first row and above the lower surface of the carrier 10. By way of example, a distance between the second plane E2 and the lower surface (cf. Vf, Vg in Fig. 3a) may lie within a range of 1 mm to 3 mm.

According to the depicted special exemplary embodiment, the directions R1, R2 are oriented parallel to one another. This does not have any limiting effect on the present invention. The directions R1, R2 may also be oriented non-parallel to one another, as long as a displacement distance Ve and/or Vd > 0 is determined between the first contact end 14a and the second contact end 16a in the view shown. This can be accomplished e.g. in that the solder pin 1 shown in Fig. 1 is injected into the carrier such that the lower subsection 7a 1 in Fig. 1 will be oriented perpendicular to the lower surface of the carrier 10 in Fig. 3a (cf. also the lower surface U of the carrier 10 in Fig. 2a). When the carrier 10 is viewed along the top view direction A (and thus parallel to the direction of extension of the lower subsection 7a1 of the solder pin 1 in Fig. 1), the first contact ends 14a are therefore not covered by the second contact ends 16a.

In the SMD devices described hereinbefore with respect to Fig. 2a, 2b and 3a, the following exemplary embodiments are disclosed:

In an exemplary embodiment, an SMD device is provided, which comprises an electronic component and the carrier 10 holding the electronic component, the carrier 10 having provided thereon at least one solder pin of the type described above with respect to Fig. 1. The SMD device can thus be connected to a circuit board and the solder pin is oriented in the carrier 10, so that the connecting sub-portion (cf. 7a1 in the above described embodiments) following the first contact end (cf. 3 in the above described embodiments) is oriented substantially perpendicular to a base of the SMD device. According to one example, the solder pin is injected into the carrier 10 and the connecting portion (cf. 7 in the above described embodiments) extends fully within the carrier 10.

Fig. 3b shows an alternative embodiment, according to which conventional U-shaped solder pins have been injected into the carrier 10 such that first contact ends 14a are not covered by second contact ends 16a, when the carrier is viewed along the top view direction A. An advantageous solder pin inspection, in the case of which the first contact ends 14a are not covered by the second contact ends 16a, is accomplished in this way. Flowever, if the wires are not round, like those shown in the figures, this will lead to a tilted arrangement on a circuit board. The contact ends will then not rest on a circuit board in planar contact therewith, but they will rest thereon on an edge.

According to various exemplary embodiments of the invention, illustrative values for at least one of the displacement distances Vy, Vd, Ve, Vb, Vc may lie in a range of 0.3 mm to 2 mm, preferably in a range of 0.3 mm to 1mm.

According to various illustrative embodiments, at least one distance of Vy, Vz, Vb, Vc, Vd, Ve, Vf, Vg may differ from at least one additional of the distances Vy, Vz, Vb, Vc, Vd, Ve, Vf, Vg. In some examples, the distances Vy, Vb, Vc, Vd, Ve may be identical.

According to various exemplary embodiments of the invention, illustrative values for the displacement distance Vz may lie in a range of 2 mm to 3 mm.

Although the solder pins shown in the figures consist of non-round conductive wires, this does not have a limiting effect on the present invention. Alternatively, the solder pins according to the invention may also consist of round conductive wires.

Claims

1. An SMD device comprising an electronic component, a carrier (10) holding the electronic component and a plurality of U-shaped solder pins (12a; 12b), which are attached to the carrier (10) and which each have a first contact end (14a; 14b) to be soldered to a circuit board and a second contact end (16a; 16b) connected to a connecting wire of the electronic component, the first contact ends (14a; 14b) being arranged on at least one side of the carrier (10) in a first row (E1), and a second row (E2) consisting of the second contact ends (16a; 16b) being defined above said first row (E1) on the corresponding side of the carrier (10), characterized in that, in a top view direction (A) perpendicular to a direction of extension (R1; R2) of the first and/or second row (E1, E2), at least some of the solder pins have the respective first contact ends (14a; 14b) displaced by a displacement distance (Vb, Vc, Vd, Ve) relative to the respective second contact ends (16a; 16b) along said direction of extension (R1, R2).

2. The SMD device according to claim 1, wherein the displacement distance lies in a range of 0.3 mm to 2 mm, preferably in a range of 0.3 mm to 1 mm.

3. The SMD device according to claim 1 or 2, wherein the first contact end (14a; 14b) and the second contact end (16a; 16b) of each solder pin are connected by a connecting portion (7) extending in the carrier (10), wherein the connecting portion (7) comprises at least one connecting sub-portion (7a) extending along the top view direction and a connecting sub-portion (7b) extending parallel to the direction of extension of the first and/or second row (E1, E2).

4. The SMD device according to claim 1 or 2, wherein the first contact end (14a) and the second contact end (16a) of each solder pin are connected by a connecting portion (18a) extending in the carrier, wherein the connecting portion (18a) extends in the carrier, at least sectionwise, at an angle having a magnitude between 0° and 90° relative to the direction of extension of the first and/or second row (E1, E2).

5. The SMD device according to one of the claims 1 to 4, wherein the electronic component is configured as an inductive component comprising a winding connected to two second contact ends of two solder pins, or a plurality of windings each connected to two contact ends of two solder pins.