Surface mounted electronic component

A surface mounted electronic component is provided. The surface mounted electronic component includes a main body, a circuit element, a conductive electrode, and a virtual electrode. The circuit element is arranged in the main body. The conductive electrode is disposed on an outer surface of the main body, wherein the conductive electrode electrically is connected to the circuit element. The virtual electrode is disposed on the outer surface of the main body, wherein the virtual electrode lies near the conductive electrode. There is a distance between the virtual electrode and the conductive electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 98128570, filed on Aug. 25, 2009. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

1. Field of the Invention

The invention relates to an electronic component capable of being welded to a circuit board. More particularly, the invention relates to a surface mounted electronic component.

2. Description of Related Art

To reduce sizes of electronic products, a surface mount technology (SMT) is widely applied to the present electronic products (such as computer products, home appliances, electronic toys, electronic equipments). Especially, functions of mobile electronic products such as mobile phones, personal digital assistants (PDAs), notebooks, etc., become versatile, and sizes and weights thereof become smaller and lighter. The SMT is a latest assembling and welding technique in a machining process of combining electronic components and a printed circuit board (PCB).

The assembling and welding method of the SMT is to use a solder paste screen printer to print solder paste on a pad surface of the PCB, and then uses a mounter to mount surface mount devices (SMDs) to the pads. The SMDs include resistors, capacitors, inductors, diodes, transistors and/or integrated circuits (ICs), etc. A hot air reflow process is performed to the PCB mounted with the solder paste and the SMDs to melt the solder paste, so as to combine the SMDs and the pads of the PCB, and now the assembling and the welding are completed.

To cope with requirement of lightness, slimness, shortness and smallness of the electronic products, an assembling density of the devices on the PCB is increased. To avoid a problem of mount offset, etc., an assembling precision of the SMDs is highly required. To cope with a requirement of the assembling precision, a size of a conductive electrode of a general SMD is required to comply with a size of the pad on the PCB.FIG. 1AandFIG. 1Bare diagrams illustrating pads of different sizes matched to the corresponding sizes of conductive electrodes. Referring toFIG. 1A, if pads111on a PCB110of a certain client are designed to have a large size, an SMD120must have relatively large conductive electrodes121. Referring toFIG. 1B, if pads131on a PCB130of another certain client are designed to have a small size, an SMD140must have relatively small conductive electrodes141even if the SMD120and the SMD140have a same device size (for example, 3 mm×3 mm) or a same characteristic specification (for example, the SMDs are all resistors of 1 mΩ). Namely, regarding the SMDs having the same device size or characteristic specification, the SMDs having different sizes of the conductive electrode have to be designed and manufactured according to different pad sizes required by different clients.

Conventionally, if the SMD with a single type of package is welded to the pads of different sizes, the SMD is probably slid in case that the solder paste is melted, which may cause problems of inaccurate alignment and unstable welding, etc., so that the assembling precision cannot be satisfied. For example, if the SMD140ofFIG. 1Bis welded on the pads111ofFIG. 1A, in case that the solder paste is melted, the relatively small conductive electrode141is probably slid within a range of the large pad111. If the SMD120with relatively large conductive electrodes121ofFIG. 1Ais welded to the relatively small pads131ofFIG. 1B, a similar problem is also encountered.

Therefore, regarding the conventional technique, a manufacturer requires to design and manufacture a plurality of types of SMDs with different conductive electrode specifications, so as to match the pads of different sizes. Since the SMDs of the same characteristic specification must have different conductive electrode specifications, a production control thereof is complicated. Moreover, to satisfy client's design requirements of different pad sizes, the SMDs of different conductive electrode specifications have to be stocked, which may increase an inventory cost.

SUMMARY

The invention is directed to a surface mounted electronic component, which can be welded to pads of different sizes and geometric shapes.

The invention provides a surface mounted electronic component including a main body, a circuit element, a conductive electrode, and a first virtual electrode. The circuit element is arranged in the main body. The conductive electrode is disposed on an outer surface of the main body, wherein the conductive electrode is electrically connected to the circuit element. The first virtual electrode is disposed on the outer surface of the main body, wherein the first virtual electrode is located near the conductive electrode. There is a distance between the first virtual electrode and the conductive electrode.

The invention provides an electronic component adapted to be mounted to a circuit board having pads of different sizes through a surface mount technology (SMT). The electronic component includes a main body, a circuit element, a pair of conductive electrodes, and a pair of first virtual electrodes. The main body has a lower surface. The circuit element is arranged in the main body. The pair of conductive electrodes are disposed at two sides of the lower surface of the main body, wherein the conductive electrodes are electrically connected to the circuit element. The first virtual electrodes are disposed on the lower surface of the main body, wherein each of the first virtual electrode is located near one of the conductive electrodes. There is a distance between the first virtual electrode and the conductive electrode.

In an embodiment of the invention, positions of the conductive electrode and the first virtual electrode correspond to a geometric shape of a first pad of the circuit board, so that the conductive electrode and the first virtual electrode are all welded to the first pad.

In an embodiment of the invention, the positions of the conductive electrode and the first virtual electrode correspond to a geometric shape of a second pad of the circuit board, so that when the conductive electrode is welded to the second pad, the first virtual electrode is located outside the second pad.

According to the above descriptions, the surface mounted electronic component of the invention can be applied to a printed circuit board having different pad sizes, so as to reduce a difficulty of production control and reduce an inventory cost. Moreover, an assembling precision of the surface mounted electronic component and the printed circuit board can be increased, so as to avoid a problem of mount offset.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

FIGS. 2A-2Care diagrams illustrating a surface mounted electronic component according to a first embodiment of the invention. The surface mounted electronic component200ofFIG. 2Aincludes a main body202, a circuit element201, conductive electrodes210and220, and first virtual electrodes230and240. It should be noticed that to clearly introduce the feature of the present embodiment, the surface mounted electronic component (for example, an inductor, a capacitor, a resistor, etc.) having two conductive electrodes is taken as an example for description, though the invention is not limited thereto. Those skilled in the art can deduce other surface mounted electronic components having more conductive electrodes according to a description of the present embodiment.

The embodiment is described mainly based on a right part (the conductive electrode210and the first virtual electrode230) of the surface mounted electronic component200, and description of a left part (the conductive electrode220and the first virtual electrode240) of the surface mounted electronic component200can be deduced by analogy.

Referring toFIG. 2A, the circuit element201is arranged in the main body202for providing rated functions of the surface mounted electronic component200. For example, in case that the surface mounted electronic component200is a choke, the circuit element201can be a coil conductor or a metal sheet of a low temperature coefficient, and by disposing a metal coil in the main body202formed by a magnetic material, electric power can be stored in form of a magnetic field. Moreover, the conductive electrode210and220are disposed on an outer surface of the main body202. The conductive electrodes210and202are electrically connected to the circuit element201, respectively. The first virtual electrodes230and240are disposed on the outer surface of the main body202. Here, the conductive electrodes210and220and the first virtual electrodes230and240are disposed on a lower surface206of the main body202, wherein the conductive electrode210and the first virtual electrode230are disposed at the right side of the lower surface206of the main body202, and the conductive electrode220and the first virtual electrode240are disposed at the left side of the lower surface206of the main body202, so as to facilitate welding to a printed circuit board (not shown). Wherein, materials of the conductive electrodes210and220and the first virtual electrodes230and240are the same, which are, for example, silver or tin, etc. In other embodiment, the material of the first virtual electrodes230and240can be different to that of the conductive electrodes210and220, for example, the conductive electrodes210and220are formed by a plated copper and nickel-tin layer, and the first virtual electrodes230and240are formed by a silver layer or a solder layer.

The first virtual electrode230is located near the conductive electrode210, and there is a distance A between the first virtual electrode230and the conductive electrode210. Those skilled in the art can determine a value of the distance A according to an actual design requirement. By suitably determining the value of the distance A, a situation that the conductive electrode210is welded to connect the first virtual electrode230due to an excessively close distance there between can be prevented. For example, the distance A is not less than 0.09 mm, and preferably the distance A is not less than 0.2 mm. Deduced by analogy, the first virtual electrode240is located near the conductive electrode220, and there is also a distance A between the first virtual electrode240and the conductive electrode220. In the present embodiment, if a size of the lower surface206of the surface mounted electronic component200is 3 mm×3 mm, the distance A can be between 0.09 mm and 0.8 mm. The distance A can also be between 0.2 mm and 0.5 mm according to a size design of the pads on the circuit board.

Those skilled in the art can determine whether the first virtual electrode230is electrically connected to the conductive electrode210and whether the first virtual electrode240is electrically connected to the conductive electrode220according to an actual design requirement. In the present embodiment, the first virtual electrode230is electrically isolated from the circuit element201and the conductive electrode210. In other embodiments, if the first virtual electrode230is electrically connected to the conductive electrode210, an effect of the present embodiment can also be achieved.

Positions of the conductive electrode210and the first virtual electrode230correspond to a geometric shape of a pad (not shown) of the circuit board. Therefore, when the surface mounted electronic component200is welded to a large pad of the circuit board, the conductive electrode210and the first virtual electrode230are all welded to the same large pad. When the surface mounted electronic component200is welded to a small pad of the circuit board, the positions of the conductive electrode210and the first virtual electrode230also correspond to a geometric shape of the small pad, so that when the conductive electrode210is welded to the small pad, the first virtual electrode230is located outside the small pad. Examples ofFIG. 2BandFIG. 2Care used for a detailed description below.

FIG. 2BandFIG. 2Care schematic diagrams illustrating the surface mounted electronic component200ofFIG. 2Awelded to the circuit board according to an embodiment of the invention. InFIG. 2BandFIG. 2C, a left side of each diagram is a top view of the circuit board (110or130) without being welded by the surface mounted electronic component200, and a right side of each diagram is a top view of the circuit board (110or130) welded by the surface mounted electronic component200.

Referring toFIG. 2B, positions of the conductive electrodes210and220and the first virtual electrodes230and240respectively correspond to geometric shapes of the first pads111and112of the circuit board110. Therefore, when the surface mounted electronic component200is welded to the circuit board110, the conductive electrode210and the first virtual electrode230are all welded to the same first pad111, and the conductive electrode220and the first virtual electrode240are all welded to the same first pad112. Therefore, although a width C of the conductive electrode210is smaller than a width PW of the first pad111, since the first virtual electrode230is disposed near the conductive electrode210, and a total width from the conductive electrode210to the first virtual electrode230(a sum of the width C of the conductive electrode210, the distance A and a width B of the first virtual electrode230) is approximately equal to the width PW of the first pad111, sliding of the conductive electrode210within a range of the first pad111along a Y-axis direction in case that the solder paste is melted can be avoided. Moreover, in the present embodiment, it is also assumed that a length D of the first virtual electrode230is approximately equal to a length PL of the first pad111, so that sliding of the first virtual electrode230within the range of the first pad111along an X-axis direction in case that the solder paste is melted can be avoided.

Referring toFIG. 2C, the positions of the conductive electrodes210and220and the first virtual electrodes230and240respectively correspond to geometric shapes of second pads131and132of the circuit board130, wherein sizes of the geometric shapes of the second pads131and132are smaller than that of the geometric shapes of the first pads111and112of the circuit board110(shown inFIG. 2B). Therefore, when the surface mounted electronic component200is welded to the circuit board130, the conductive electrode210is welded to the second pad131, and the first virtual electrode230is located outside the second pad131. Since the width C of the conductive electrode210is approximately smaller than or equal to a width PW′ of the second pad131, sliding of the conductive electrode210within a range of the second pad131along the Y-axis direction in case that the solder paste is melted can be avoided. Although the surface mounted electronic component200has the first virtual electrode230, since there is the distance A between the conductive electrode210and the first virtual electrode230, the first virtual electrode230does not interfere the welding between the conductive electrode210and the second pad131.

The distance A, the width B of the first virtual electrode230, the width C of the conductive electrode210and the length D of the first virtual electrode230(or the conductive electrode210) can be determined according to the sizes of the pads on the circuit board, so that the surface mounted electronic components of a single specification can be mounted to the pads of different sizes on the circuit board. For example, in the present embodiment, to ensure that the surface mounted electronic component200can be mounted to both of the circuit board110having the first pad111and the circuit board130having the second pad131, and ensure an assembling precision and avoid a mount offset, widths of the components of the surface mounted electronic component200and the width of the pad on the circuit boards are required to satisfy a following equation (1): the distance A≦(the width PW of the first pad−the width C of the conductive electrode−the width B of the first virtual electrode), and a following equation (2): the distance A≧(the width PW′ of the second pad−the width C of the conductive electrode).

FIGS. 3A-3Dare diagrams illustrating a surface mounted electronic component according to a second embodiment of the invention.FIG. 3Ais a three-dimensional view of the surface mounted electronic component300, andFIG. 3Bis a top view of the surface mounted electronic component300. A difference between the second embodiment and the first embodiment is that the surface mounted electronic component300further includes second virtual electrodes350and360, and the second virtual electrodes350and360and first virtual electrodes330and340are respectively disposed at two sides of conductive electrodes310and320. For simplicity's sake, the components (for example, a main body302, a lower surface306, a circuit element301, the conductive electrodes310and320, and the first virtual electrodes330and340, etc.) in the second embodiment that are similar or the same to that of the first embodiment are represented by similar or the same reference numbers, and the related descriptions thereof are not repeated.

Referring toFIG. 3B, in the present embodiment, the conductive electrodes310and320, the first virtual electrodes330and340, and the second virtual electrodes350and360are all disposed on the lower surface306of the main body302. There is the distance A between the first virtual electrode330and the conductive electrode310, and there is also the distance A between the second virtual electrode350and the conductive electrode310. It should be noticed that although the first virtual electrode330and the second virtual electrode350are symmetrically disposed at two sides of the conductive electrode310to form the same distance A, the invention is not limited thereto, and the distances respectively between the first virtual electrode330, the second virtual electrode350and the conductive electrode310can also be different, and those skilled in the art can determine a value of the distance A according to an actual design requirement. In the present embodiment, the distance A is between 0.2 mm and 0.5 mm, so as to ensure that the first virtual electrode330and the second virtual electrode350are not welded to connect the conductive electrode310due to excessive close distance.

FIGS. 3C and 3Dare schematic diagrams illustrating the surface mounted electronic component300ofFIG. 3AandFIG. 3Bwelded to the circuit board according to an embodiment of the invention. InFIG. 3CandFIG. 3D, a left side of each diagram is a top view of the circuit board without being welded by the surface mounted electronic component300, and a right side of each diagram is a top view of the circuit board welded by the surface mounted electronic component300. The embodiment is described mainly based on a right part (the conductive electrode310, the first virtual electrode330and the second virtual electrode350) of the surface mounted electronic component300, and description of a left part (the conductive electrode320, the first virtual electrode340and the second virtual electrode360) of the surface mounted electronic component300can be deduced by analogy.

Referring toFIG. 3C, positions of the conductive electrode310, the first virtual electrode330and the second virtual electrode350correspond to the geometric shape of the first pad111of the circuit board110. In the present embodiment, positions of the conductive electrode310, the first virtual electrode330and the second virtual electrode350are aligned in a straight line, and the first virtual electrode330and the second virtual electrode350are symmetrically disposed at two sides of the conductive electrode310. Therefore, when the surface mounted electronic component300is welded to the circuit board110, the conductive electrode310, the first virtual electrode330and the second virtual electrode350are all welded to the same first pad111. Although a width C of the conductive electrode310is smaller than the width PW of the first pad111, since the first and the second virtual electrodes330and350are disposed near the conductive electrode310, and a total width from the first virtual electrode330to the second virtual electrode350(a sum of a width B of the first virtual electrode330, the distance A, the width C of the conductive electrode310, the distance A and the width B of the second virtual electrode350) is approximately equal to the width PW of the first pad111, sliding of the conductive electrode310within a range of the first pad111along the Y-axis direction in case that the solder paste is melted can be avoided. Moreover, in the present embodiment, it is also assumed that a length D of the first and the second virtual electrode330and350is approximately equal to the length PL of the first pad111, so that sliding of the first and the second virtual electrode330and350within the range of the first pad111along the X-axis direction in case that the solder paste is melted can be avoided.

Referring toFIG. 3D, the positions of the conductive electrode310, the first virtual electrode330and the second virtual electrode350correspond to a geometric shape of second pad131of the circuit board130. Therefore, when the surface mounted electronic component300is welded to the circuit board130, the conductive electrode310is welded to the second pad131, and the first and the second virtual electrode330and350are located outside the second pad131. Since the width C of the conductive electrode310is approximately equal to a width PW′ of the second pad131, sliding of the conductive electrode310within a range of the second pad131along the Y-axis direction in case that the solder paste is melted can be avoided. Moreover, since the length of the conductive electrode310is approximately equal to the length PL of the second pad131, sliding of the conductive electrode310within a range of the second pad131along the X-axis direction in case that the solder paste is melted can be avoided. Although the surface mounted electronic component300has the first and the second virtual electrodes330and350, since there is the distance A respectively between the conductive electrode310and the first and the second virtual electrodes330and350, the first and the second virtual electrodes330and350do not interfere the welding between the conductive electrode310and the second pad131.

The distance A, the widths B of the first and the second virtual electrode330and350, the width C of the conductive electrode310and the length D of the first and/or the second virtual electrode330and/or350(or the conductive electrode310) can be determined according to the sizes of the pads on the circuit board, so that the surface mounted electronic components of a single specification can be mounted to the pads of different sizes on the circuit board. In the present embodiment, the distance A satisfies a following equation: (the width PW′ of the second pad−the width C of the conductive electrode)≦the distance A≦(the width PW of the first pad−the width C of the conductive electrode−the width B of the first virtual electrode−the width B of the second virtual electrode)/2.

Those skilled in the art can change positions and a number of the electrodes ofFIG. 3A(orFIG. 3B) according to an actual design requirement. If the circuit board has pads of three different widths of large, medium and small, the surface mounted electronic component300ofFIG. 3Amay further have a third virtual electrode335and a fourth virtual electrode355(referring toFIG. 3E), wherein the third virtual electrode335and the fourth virtual electrode355can be disposed at edges of the right side of the lower surface306of the surface mounted electronic component300with reference of the first virtual electrode330and the second virtual electrode350, and the electrodes are arranged in a sequence of the third virtual electrode335, the first virtual electrode330, the conductive electrode310, the second virtual electrode350and the fourth virtual electrode355. There is the distance A between the third virtual electrode335and the first virtual electrode330, and there is also the distance A between the second virtual electrode350and the fourth virtual electrode355. Therefore, when the conductive electrode310is welded to a large pad, the third virtual electrode335, the first virtual electrode330, the conductive electrode310, the second virtual electrode350and the fourth virtual electrode355are all welded to the same large pad. When the conductive electrode310is welded to a medium pad, the first virtual electrode330, the conductive electrode310and the second virtual electrode350are all welded to the same medium pad, and the third virtual electrode335and the fourth virtual electrode355are located outside the medium pad. When the conductive electrode310is welded to a small pad, the conductive electrode310is welded to the small pad, and the first to the fourth virtual electrodes330,350,335and355are all located outside the small pad.

FIGS. 4A-4Care diagrams illustrating a surface mounted electronic component400according to a third embodiment of the invention. A difference between the third embodiment and the first embodiment is that first virtual electrodes430and440are located between two conductive electrodes410and420. For simplicity's sake, the components (for example, a main body402, a lower surface406, a circuit element401, the conductive electrodes410and420, and the first virtual electrodes430and440, etc.) in the third embodiment that are similar or the same to that of the first embodiment are represented by similar or the same reference numbers, and the related descriptions thereof are not repeated.

Referring toFIG. 4A, in the present embodiment, the conductive electrodes410and420, the first virtual electrodes430and440are all located on the lower surface406of the main body402, and the first virtual electrodes430and440are respectively located between the conductive electrodes410and420. There is a distance A respectively between the first virtual electrodes430and440and the conductive electrode410and420. Those skilled in the art can determine a value of the distance A according to an actual design requirement. For example, the distance A is not less than 0.09 mm, and is preferably not less than 0.2 mm, so as to avoid a connection of the solder pastes due to excessive close distance there between when the solder pastes are melted. In the present embodiment, the distance A can be between 0.2 mm and 0.4 mm.

Referring toFIG. 4BandFIG. 4C, positions of the conductive electrode420, the first virtual electrode440, the first virtual electrode430and the conductive electrode410are aligned in a straight line along an X-axis direction, and the four electrodes all have a width of C. In the present embodiment, positions of the conductive electrodes410and420and the first virtual electrodes430and440correspond to geometric shapes of first pads151and152of the circuit board150, and correspond to geometric shapes of second pads161and162of the circuit board160.

Therefore, when the surface mounted electronic component400is welded to the circuit board150, the conductive electrode410and the first virtual electrode430are all welded to the same first pad151. In the present embodiment, the width C of the conductive electrode410and/or the first virtual electrode430is approximately equal to a width PW of the first pad151, so that sliding of the conductive electrode410and the first virtual electrode430within a range of the first pad151along the Y-axis direction in case that the solder paste is melted can be avoided. Moreover, although a length D of the conductive electrode410is smaller than a length PL of the first pad151, since the first virtual electrode430is disposed near the conductive electrode410, and a total length from the first virtual electrode430to the conductive electrode410(a sum of a length E of the first virtual electrode430, the distance A and the length D of the conductive electrode410) is approximately equal to the length PL of the first pad151, sliding of the conductive electrode410within the range of the first pad151along the X-axis direction in case that the solder paste is melted can be avoided.

Moreover, when the surface mounted electronic component400is welded to the circuit board160, the conductive electrode410is welded to the second pad161, and the first virtual electrode430is located outside the second pad161(shown inFIG. 4C). Since the length D of the conductive electrode410is approximately equal to a length PL′ of the second pad161, sliding of the conductive electrode410within the range of the second pad161along the X-axis direction in case that the solder paste is melted can be avoided. Moreover, since the width C of the conductive electrode410is approximately equal to a width PW of the second pad161, sliding of the conductive electrode410within the range of the second pad161along the Y-axis direction in case that the solder paste is melted can be avoided. Although the surface mounted electronic component400has the first virtual electrode430, since there is the distance A between the conductive electrode410and the first virtual electrode430, the first virtual electrode430does not interfere the welding between the conductive electrode410and the second pad161.

The distance A, the length E of the first virtual electrode430, the width C of the conductive electrode410(or the first virtual electrode430) and the length D of the conductive electrode410can be determined according to the size of the pad on the circuit board. In the present embodiment, the width C of the conductive electrode410is between 0.8 mm and 1.1 mm, the length E of the first virtual electrode430is between 0.2 mm and 0.4 mm. Moreover, a difference between the width PW of the second pad161and the width C of the conductive electrode410is between 0 mm and 0.8 mm, and a difference between the length PL′ of the second pad161and the length D of the conductive electrode410is between 0 mm and 0.8 mm.

In summary, those skilled in the art can determine the positions, sizes and a number of the virtual electrodes according to an actual design requirement, so that the surface mounted electronic component using the virtual electrodes can be applied to pads of different sizes and geometric shapes, so as to reduce a difficulty of production control and reduce an inventory cost. Moreover, an assembling precision of the surface mounted electronic component and the printed circuit board can be increased, so as to avoid a problem of mount offset.