TWI391056B - Pad, circuit board and electronic device using the same - Google Patents

Description

Pad, circuit board and electronic device having the same

The present invention relates to a pad for soldering a surface mount component, and a circuit board and an electronic device having the pad.

With the continuous development of science and technology, modern society is closely related to electronic technology, and electronic products such as mobile phones, walkie-talkies, portable computers, memory, hard disk drives, optical disk drives, and high-definition televisions are increasingly used. In order to be convenient to carry and use, the user puts forward higher requirements for miniaturization and light weight of the product. Surface Mount Technology (SMT) conforms to this trend and lays the foundation for light, thin, short and small electronic products.

Since the 1990s, SMT technology has reached a mature stage. With the rapid development of photovoltaic and micro-electric manufacturing process technology, new high-density assembly technologies are emerging. Among them, Ball Grid Array (BGA) is a high-density assembly technology that has entered the practical stage.

BGA surface mount components are soldered with a number of spherical solder bumps or solder balls (hereinafter referred to as solder joints), which enable electrical connection between BGA surface mount components and circuit substrates such as printed circuit boards. connection. The advantage of BGA technology is to improve the assembly yield; the thickness and weight are reduced compared with the previous packaging technology; the parasitic parameters are reduced, the signal transmission delay is small, the frequency of use is greatly improved; the assembly can be used for coplanar welding with high reliability. The main disadvantage is that the soldering quality of the solder joints on the solder joints and the circuit board is relatively low, and soldering point drift, soldering, soldering, soldering, solder joint cracking, etc. are prone to problems, making the BGA device in many fields. The application is limited.

The above problems are also prone to occur in other surface mount technologies for the following reasons: conventional pads are generally circular or have the same shape as the pins/joints of surface mount components, and their area is more than the surface mount components. The area of the part is large, so when the surface mount component is soldered to the circuit board, the tension of the solder paste during the solder paste fixing process tends to pull the surface mount component away from its original set center point, so that the surface mount The pins of the component drift on the pad, which causes the position of the surface mount component to shift, and the soldering and solder spillage are also prone to occur during the soldering process, thereby causing a short circuit between the pads. . In particular, in the assembly of BGA surface mount components, the pads on the board are circular, which are connected to the BGA surface mount components by a ball-shaped solder joint, which is limited by the shape of the pads on the board. There is only one support point between the solder joint and the pad, and the surface mount component and the pad have weaker thrust resistance. When the board is heated, it will be deformed (bent), resulting in solder joints with only one support point and the pads forming an empty solder at their solder joints. When the temperature is high or other conditions cause the thrust resistance of the BGA component to drop, there may even be a solder joint (solder ball) tin crack and a BGA surface mount component falling off, which limits the BGA device in many fields of application. .

In view of this, it is necessary to provide an improved pad to improve the solder quality of the surface-substrate and pad.

In addition, it is also necessary to provide a circuit board and an electronic device having the pad.

A pad for soldering surface mount components, including: a central portion, And a plurality of extensions extending outward from the central portion, the plurality of extensions having a gap therebetween, the extension being T-shaped.

A circuit board having a plurality of pads formed on a surface thereof for soldering surface mount components, at least one of the plurality of pads including a central portion, and a plurality of extensions extending outward from the central portion, The plurality of extensions have a gap with each other, and the extension has a T shape.

An electronic device comprising at least one circuit board and a surface mount component soldered on the circuit board, the circuit board surface being formed with a plurality of pads for soldering the surface mount component; At least one of the pads includes a central portion and a plurality of extensions extending outwardly from the central portion, the plurality of extensions having a gap therebetween, the extension being T-shaped.

The pad of the present invention has a central portion and a plurality of extensions, thereby limiting the connection portion of the surface mount component to a central position on the pad, reducing the drift amplitude, so as to accurately position the surface mount component; After adopting the above shape, the solder will reach the extension of the pad during the soldering process, so that the connection portion of the surface mount component soldered to the pad or the solder joint and the pad have a plurality of subsequent points, increasing The surface mount components and the pad's thrust resistance also avoid the phenomenon of void soldering, over-welding, and solder spillage, in addition to saving solder. In summary, the present invention can improve the production yield of electronic products and reduce the generation of maintenance parts.

As shown in FIG. 1, the pads 10 are disposed on the circuit board 20. Wherein, the circuit board 20 can be a printed circuit board, and the pad 10 serves as a connection point between the electronic circuit and the surface mount component in the circuit board 20 for soldering the surface mount component to The surface mount component is electrically connected to the electronic circuitry in circuit board 20. The pad 10 may be bare copper or an electric conductor plated or doped with at least one of a conductive metal material such as gold, silver, copper, iron, tin, aluminum, and lead, and may be formed by a conventional method such as chemical etching. I will not repeat them here.

In this embodiment, the periphery of the pad 10 is substantially circular, including a square central portion 11, and four extending portions 13 extending outward from the four sides of the square, respectively, and the extending portions 13 are not connected to each other. The extension portion 13 is approximately T-shaped and includes a connection end 131 connected to the center portion 11 and a free end 133 away from the center portion 11, the width W1 of the free end 133 being greater than the width W2 of the connection end 131. The size of the periphery of the pad 10 may be the same as the size of the existing pad, or may be slightly larger or slightly smaller than the existing pad according to the actual situation.

After the pad 10 having the above shape is used, in the process of soldering the surface mount component and the circuit board 20, the solder automatically fills the center portion 11 and the extension portion 13 after being melted by heat, thereby effectively preventing over-welding and soldering. And the appearance of solder spills. Meanwhile, since the plurality of extension portions 13 are evenly distributed around the periphery of the center portion 11, the surface tension of the solder can automatically limit the position of the connection portion of the surface mount member to the center portion 11 during the solder reflow process, thereby limiting the surface sticker. The drift of the component on the pad 10 reduces the drift amplitude, enabling precise positioning of the surface mount components. And when the peripheral shape of the pad 10 is the same as the existing pad, the actual area of the pad 10 will be reduced relative to the existing pad area, thereby saving the use of solder.

In particular, when the surface mount component is soldered to the pad 10, each of its connections or pads is fixedly coupled to the central portion 11 and the plurality of extensions 13 of the pad 10 such that the surface soldered to the pad There are a plurality of support points and connection points between the connection portion of the mounting component or the solder joint and the pad 10, and the addition The surface mount component and the pad are resistant to thrust, and the width W1 of the free end 133 is greater than the width W2 of the connection end 131. This advantage is improved, and the soldering and solder joints (solder balls) caused by the deformation of the circuit board 20 and the like are effectively prevented. The phenomenon of tin cracking and solder joint falling off improves the production yield of electronic products and reduces the generation of maintenance parts.

In other embodiments, the central portion 11 of the pad 10 may be circular, and the extension 13 may be fan-shaped, which may include four extensions (as shown in FIG. 2), and may also include three extensions (FIG. 3). . It can be understood that the specific shape of the pad 10 can be variously deformed according to the shape of the connecting portion of the surface mounting component, but both include a central portion and a plurality of extending portions extending outward from the central portion for surface mounting. Accurate positioning of components, increase the thrust resistance of surface mount components and pads, save solder, avoid air soldering, over-welding, solder spillage, and improve the production yield of electronic products.

It will be appreciated that the circuit board 20 of the present invention can have a plurality of pads forming an array of pads to solder a plurality of surface mount components, as shown in FIGS. 4 and 5. Some of the pads in the pad array may adopt the shape described in the present invention, or all of the pads may adopt the shape described in the present invention, as shown in FIG. 5, wherein the pad 70 is a conventional circular pad, soldered. The size of the periphery of the disk 10 is the same as that of the pad 70.

Please refer to FIG. 6 , which illustrates an electronic device 100 according to an embodiment of the present invention, which includes a circuit board 30 and a surface mount component 50 . The surface mount component 50 can be a resistor, a capacitor, an integrated circuit component, a button or a card holder, or the like. In this embodiment, the surface mount component 50 is an integrated circuit component packaged by a BGA technology, and a ball grid array composed of a plurality of solder balls 60 is disposed on a lower surface thereof. A plurality of pads 40 are disposed on the circuit board 30, and each of the pads 40 includes a central portion, and a plurality of extending portions extending outward from the central portion, the plurality of extending portions are evenly distributed around the periphery of the central portion, and the width of the free end of the extending portion is greater than the width of the connecting end thereof, and the shape thereof may be as shown in FIG. The shape of the perimeter can be the same size as the existing circular pad.

In the assembly process, the electronic device 100 first applies a solder material such as solder paste to the pad 40 of the circuit board 30, and then mounts the surface mount component 50 on the circuit board 30 to make the surface mount component 50. The plurality of solder balls 60 are located on the corresponding pads 40, and then the surface mount component 50 is soldered to the circuit board 30 through a reflow oven to form the electronic device 100.

It is to be understood that those skilled in the art can make various other changes and modifications in accordance with the technical concept of the present invention, and all such changes and modifications are intended to fall within the scope of the appended claims.

10‧‧‧ pads

20‧‧‧ boards

11‧‧‧ Central Department

13‧‧‧Extension

131‧‧‧Connecting end

133‧‧‧Free end

W1‧‧‧ width of the free end

W2‧‧‧Width of the connector

70‧‧‧ pads

100‧‧‧Electronic devices

30‧‧‧ boards

40‧‧‧ pads

50‧‧‧Surface Mounting Components

60‧‧‧ solder balls

1 is a schematic plan view of a pad in an embodiment.

2 is a schematic plan view of a pad in another embodiment.

3 is a schematic plan view of a pad in still another embodiment.

4 is a schematic plan view of a circuit board provided with a pad array in still another embodiment.

5 is a schematic plan view of a circuit board provided with a pad array in another embodiment.

FIG. 6 is a schematic structural view of an electronic device according to an embodiment.

10‧‧‧ pads

20‧‧‧ boards

11‧‧‧ Central Department

13‧‧‧Extension

131‧‧‧Connecting end

133‧‧‧Free end

W1‧‧‧ width of the free end

W2‧‧‧Width of the connector

Claims (12)

A pad for soldering a surface mount component, the improvement comprising: a central portion, and a plurality of extensions extending outwardly from the central portion, the plurality of extensions having a gap therebetween, the extension being T shape. The pad of claim 1, wherein each of the extensions includes a connection end connected to the central portion, and a free end; the free end has a width greater than a width of the connection end. The pad of claim 1, wherein the plurality of extensions are evenly distributed around a periphery of the central portion. The pad of claim 2 or 3, wherein the central portion is one of a circle and a polygon. A circuit board having a plurality of pads formed on its surface for soldering surface mount components, the improvement being that at least one of the plurality of pads includes a central portion and a plurality of outer portions extending outward from the central portion The extension portion has a gap between the plurality of extension portions, and the extension portion has a T shape. The circuit board of claim 5, wherein the plurality of extensions are evenly distributed around a periphery of the central portion. The circuit board of claim 5, wherein each of the extensions includes a connection end connected to the center portion, and a free end; the free end has a width greater than a width of the connection end. The circuit board of claim 6 or 7, wherein the central portion is one of a circle and a polygon. An electronic device comprising at least one circuit board and a surface mount component soldered on the circuit board, the circuit board surface being formed with a plurality of pads for soldering the surface mount component; Multiple pads At least one of the pads includes a central portion and a plurality of extensions extending outwardly from the central portion, the plurality of extensions having a gap therebetween, the extension being T-shaped. The electronic device of claim 9, wherein each of the extending portions includes a connecting end connected to the central portion, and a free end; the free end has a width greater than a width of the connecting end. The electronic device of claim 9, wherein the plurality of extensions are evenly distributed around a periphery of the central portion. The electronic device of claim 10, wherein the central portion is one of a circle and a polygon.