JP4852111B2 - Printed wiring board - Google Patents

Description

  In order to solder a two-terminal component to a pair of metal foil pads formed on the surface of a printed wiring board, the present invention is provided with a pair of solder pastes applied to the surface of the metal foil pads. The present invention relates to an improvement of a printed wiring board for surface mounting in which paste is heated and melted.

There are various soldering techniques that take into account the movement of a component due to the surface tension of molten solder when a surface-mounted component is soldered to a metal foil pad such as a copper foil.
For example, according to the following Patent Document 1 “Semiconductor Element Substrate Assembly Method”, an element mounting land corresponding to the semiconductor element is provided on the element substrate, and solder and flux are applied to the land. In a method of assembling a semiconductor element, the semiconductor element is mounted on the element substrate by passing the heating element in a state where the semiconductor element is mounted on the land, melting the solder, and attaching the semiconductor element to the element substrate. The method for assembling a substrate of a semiconductor device, wherein the land to be provided has the same shape as a terminal portion of a semiconductor device attached to the land or a shape including the same shape in a part of an outline. Is disclosed.
As a result, the land provided on the element substrate has the same shape as the terminal portion of the semiconductor element, or a shape including the same shape as a part of the outline, so that the circuit component can be placed on the element substrate with moderate accuracy. However, when passing through the heating furnace in this state, the semiconductor element moves to a position where the shape matches the land due to the surface tension of the molten solder, and high accuracy is not required for the element substrate, chip mounter, A semiconductor element is supposed to be attached to an intended position on the element substrate.

Further, according to the following Patent Document 2 “Printed Wiring Board”, a board and at least one set of lands provided opposite to each other on the board are provided, and each of the lands has a space between these one set of lands. A printed wiring board to which a wiring pattern having a connection portion that is substantially symmetric with respect to the center is connected, and at least one of the wiring patterns connected to the set of lands is once led out onto an extension line connecting the lands. Then, a printed wiring board that changes the traveling direction is disclosed.
As a result, since the connection part of the wiring pattern is derived symmetrically from the center between the lands on which the chip parts are mounted, the surface tension generated during solder heating and melting is equal in size and balanced between both electrodes of the chip parts. In other words, it is said that it is possible to prevent chip components from shifting or rising.

Further, in relation to the present invention, according to the following Patent Document 3 “Circuit Board and Electronic Circuit Device”, a circuit board having electrode portions at positions corresponding to a large number of electrode portions of an electronic circuit element, In a circuit board that constitutes an electronic circuit device connected to an electrode portion of an electronic circuit element, at least one of the electrodes has a quadrilateral, pentagonal, hexagonal, heptagonal, or octagonal shape. A polygonal circuit board is disclosed.
Accordingly, it is possible to provide a circuit board that can easily inspect the joint portion of the electronic circuit device in which the electronic circuit element and the circuit board are joined by visual or mechanical physical methods. For example, a transmission image of the joint portion is an electrode of the circuit board. If the polygon is substantially the same as the polygon, the joining is good. If the transmission image is not a polygon that is substantially the same as the electrode of the circuit board, it can be regarded as a defect.

Japanese Patent Laying-Open No. 2005-150385 (FIG. 1, abstract) Japanese Patent Laid-Open No. 06-97638 (FIG. 1, abstract) Japanese Patent Laid-Open No. 10-335796 (FIG. 1, summary)

Patent Documents 1, 2 and 3 disclose a technique for ensuring the soldering of two parts by utilizing the surface tension at the time of melting of solder. However, the printed wiring circuit boards described in Patent Documents 1, 2, and 3 do not take into consideration variations in dimensions due to individual variations of the two-terminal components to be soldered.
Therefore, for example, the two-terminal component of the minimum size is unevenly distributed on one copper foil pad due to the surface tension of the molten solder acting on the solder surface, and soldering to the other copper foil pad cannot be performed or the solder area is very small. The problem of becoming.

  An object of the present invention is to ensure that a pair of two-terminal parts soldered to a metal pad such as a pair of copper foil pads is reliably paired by a centripetal action due to the surface tension of the molten solder, even if variations in the size of each part due to individual variations occur. It is intended to provide a printed wiring board that can be soldered to the metal foil pad and that the center position between the pair of metal foil pads and the center position of the two-terminal component can be brought close to each other.

A printed wiring board according to the present invention is formed on the surface of a printed wiring board, and a pair of metal foil pads for soldering a two-terminal component having a pair of electrodes, and a pair applied to the surface of the metal foil pads. A surface-mount printed wiring board in which the solder paste is heated and melted, and the planar shape of the pair of solder pastes before heating and melting depends on a predetermined length dimension and width dimension. A square part, a first trapezoidal part outside the square part and having a first height dimension, and a second trapezoidal part inside the square part and having a second height dimension are integrated. And the distance between the outer end portions of the square portions of the pair of solder pastes is equal to or greater than the dimension between the end faces of the rectangular electrodes of the longest two-terminal component of the two-terminal components, Solder pace Spacing of the inner end portion of the rectangular portion is less than the dimension between the end faces of the rectangular electrode of the shortest two-terminal components in the two-terminal components, a pair of rectangular electrodes the two-terminal component comprising an individual variation variations of part dimensions And the width dimension of the pair of metal foil pads is equal to or greater than the width dimension of the rectangular electrode having the maximum width dimension of the two-terminal components, and the width dimension of the square portion of the pair of solder pastes Each of the pair of metal foil pads is a square portion having an area larger than an area including the square portion and the second trapezoidal portion of the pair of solder pastes. The printed wiring board includes a third trapezoidal portion corresponding to the first trapezoidal portion of the pair of solder pastes .

The printed wiring board according to the present invention includes first and second trapezoids provided on both sides of a rectangular portion as a planar shape of a pair of solder paste provided on a pair of metal foil pads for solder connection of two-terminal components. An octagon having a portion is formed, and the dimensions of the pair of rectangular portions are determined in relation to the maximum dimension and the minimum dimension based on the variation in individual variation of the two-terminal parts. When the solder paste in the shape is heated and melted, it approaches the left and right center lines due to the centripetal action due to the surface tension of the molten solder, and even if there are individual variations in the dimensions of each part of the two-terminal component, The center position of the left and right and the center position of the two-terminal component can be brought close to each other so that two-terminal components of various dimensions can be securely soldered to the pair of metal foil pads, and the pair of metal foils The pad is composed of a square part corresponding to a pair of solder paste and a square part corresponding to the second trapezoid part, and a third trapezoid part corresponding to the first trapezoid part of the pair of solder pastes. The solder paste of the second trapezoidal part flows out over the entire rectangular part of the metal foil pad and solders the entire rectangular electrode of the two-terminal part, and the excess solder flows out of the two-terminal part and the printed wiring board. Solder balls can be prevented from being generated, and the correct combination of metal foil pads can be easily visually identified when a large number of two-terminal components are soldered in multiple rows. This has the effect of facilitating manual operations such as analysis and rework .

1 is a solder connection diagram of a standard size two-terminal component in a printed wiring board according to an embodiment of the present invention. FIG. 1 is a solder connection diagram of a two-terminal component having a minimum size in a printed wiring board according to an embodiment of the present invention. FIG. 2 is a solder connection diagram of a maximum size two-terminal component in a printed wiring board according to an embodiment of the present invention. It is a dimension figure of the copper foil pad in the printed wiring board by one Example of this invention. It is a dimension figure of the solder paste in the printed wiring board by one Example of this invention.

Embodiment 1
First, FIG. 1, which is a solder connection diagram of a standard size two-terminal component on a printed wiring board according to an embodiment of the present invention, will be described with reference to the dimensional diagrams of FIGS.
FIG. 1 (A) is a plan view of a board in which standard-sized two-terminal components 4 are evenly arranged with respect to a pair of copper foil pads 1a and 1b, and on both sides of the pair of copper foil pads 1a and 1b. The wiring patterns 2a and 2b are drawn out.
Solder pastes 3a and 3b are applied to the surfaces of the pair of copper foil pads 1a and 1b from openings (3A and 3B in FIG. 5) of a metal mask (not shown), and the solder paste is heated and melted to be cooled and solidified. By doing so, the rectangular electrodes 4a and 4b of the two-terminal component 4 are soldered to the copper foil pads 1a and 1b.
As shown in FIG. 5, the planar shape of the solder pastes 3a and 3b is a rectangular portion 30 surrounded by points P12, P13, P23, and P22, and a first trapezoidal portion 31 surrounded by points P11, P12, P22, and P21. And the second trapezoidal portion 32 surrounded by the points P13, P14, P24, and P23, and the first trapezoidal portion 31 is provided outside the rectangular portion 30 around the pair of rectangular portions 30. The second trapezoidal portion 32 is provided on the inner side. The heights L1 and L2 of the first and second trapezoidal portions 31 and 32 have different values, the inclination angle θ1 of the inclined portion of the first trapezoidal portion 31 is large, and the height dimension L1 is small. The inclination angle θ2 of the inclined portion of the second trapezoidal portion 32 is small and the height dimension L2 is large.

In addition, the length dimension of the square part 30 is L0, the width dimension is W0b, the outer distance between the pair of square parts 30 is L13a, the inner distance between the pair of square parts 30 is L13b, and the trapezoidal head of the pair of first trapezoidal parts 31 The interval between the parts is indicated by L11, and the interval between the trapezoidal heads of the pair of second trapezoidal portions 32 is indicated by L12b.
L0 = (L13a-L13b) / 2
It has become a relationship.
The planar shape of the pair of copper foil pads 1a and 1b is as shown in FIG. 4, and each of the pair of copper foil pads 1a and 1b includes a square portion 30 and a second trapezoidal portion 32 of the pair of solder pastes 3a and 3b. And a third trapezoidal portion 33 corresponding to the first trapezoidal portion 31 of the pair of solder pastes 3a and 3b, and the third trapezoidal portion 33 includes Are connected to the wiring patterns 2a and 2b.
The width dimension of the copper foil pad is W0a, the inner distance between the rectangular portions 34 of the pair of copper foil pads 1a and 1b is L12a, and the outer distance is L13a. The width dimension W0a of the copper foil pad is equal to that of the solder paste. The inner distance L12a between the square portions 34 of the pair of copper foil pads 1a and 1b is larger than the width dimension W0b, and is smaller than the distance L12b between the trapezoidal heads of the pair of second trapezoidal portions 32 of the solder paste.

FIG. 1B is a plan view of the substrate when the standard-sized two-terminal component 4 is disposed with a positional deviation with respect to the pair of copper foil pads 1a and 1b. The two-terminal component 4 is a copper foil on the right side. It is unevenly distributed on the pad 1b side.
FIG. 1C is a cross-sectional view of the printed wiring board 10 when the solder pastes 3a and 3b are heated and melted in a state where the two-terminal components 4 are unevenly distributed as shown in FIG. 3aa and 3bb adhere to the surface of the rectangular electrodes 4a and 4b of the two-terminal component 4, and a component force that moves in the direction of the arrow 8 is applied by the surface tension of the molten solder.
The surface tension is a force that works along the surface of the molten solder to shrink as much as possible to take as small an area as possible. As a result, the center position of the two-terminal component 4 is a pair of copper foil pads 1a. -It moves closer to the center position between 1b.
Further, even when the center line of the two-terminal component 4 and the center line in the left-right direction of the pair of copper foil pads 1a and 1b are deviated from each other, the two center lines move so as to coincide with each other. .
Note that solder resist films 7a and 7b are applied to the wiring patterns 2a and 2b connected to the copper foil pads 1a and 1b so that the molten solder does not flow out.

Next, FIG. 2, which is a solder connection diagram of a two-terminal component having a minimum size in a printed wiring board according to an embodiment of the present invention, will be described with reference to the dimensional diagrams of FIGS.
FIG. 2A is a plan view of the substrate when the two-terminal component 5 having the minimum size is evenly arranged with respect to the pair of copper foil pads 1a and 1b, and the dimension L13b in FIG. The distance between the end faces of the rectangular electrodes 5a and 5b is equal to or less than the distance.
FIG. 2 (B) is a plan view of the substrate when the two-terminal component 5 having the minimum size is arranged with a positional shift with respect to the pair of copper foil pads 1a and 1b. The two-terminal component 5 is a copper foil on the right side. When the end surface of one rectangular electrode 5b of the minimum two-terminal component 5 is in contact with the inclined portion of the first trapezoidal portion 31 of the one solder paste 3b when mounted unevenly on the pad 1b side, The interval L12b in FIG. 5 is determined so that the other square electrode 5a of the minimum two-terminal component 5 can contact the trapezoidal head of the second trapezoidal portion 32 of the other solder paste 3a.

FIG. 2C is a cross-sectional view of the printed wiring board 10 when the solder pastes 3a and 3b are heated and melted in a state where the two-terminal components 5 are unevenly distributed as shown in FIG. 3aa and 3bb adhere to the surface of the rectangular electrodes 5a and 5b of the two-terminal component 5, and a component force that moves in the direction of the arrow 8 is applied by the surface tension of the molten solder.
As a result, the center position of the two-terminal component 5 moves closer to the center position between the pair of copper foil pads 1a and 1b.
Similarly, even when the center line of the two-terminal component 5 and the center line in the left-right direction of the pair of copper foil pads 1a and 1b are deviated, both the center lines are moved so as to coincide with each other. Become.

Next, FIG. 3 which is a solder connection diagram of the maximum size two-terminal component in the printed wiring board according to one embodiment of the present invention will be described with reference to the dimensional diagrams of FIGS.
3A is a plan view of the substrate when the two-terminal component 6 having the maximum size is evenly arranged with respect to the pair of copper foil pads 1a and 1b. A dimension L13a in FIG. The distance between the end faces of the rectangular electrodes 6a and 6b is equal to or greater than that.
The maximum width of the two-terminal component 6 is smaller than the width W0a of the pair of copper foil pads 1a and 1b and larger than the width W0b of the pair of solder pastes 3a and 3b.
FIG. 3B is a cross-sectional view of the printed wiring board 10 when the solder pastes 3a and 3b are heated and melted in a state where the two-terminal components 6 are evenly arranged as shown in FIG. The solders 3aa and 3bb adhere to the surfaces of the rectangular electrodes 6a and 6b of the two-terminal component 6, and the surface tension of the molten solder acts equally on the left and right, so that no component force is generated to move the two-terminal component 6.
However, when the two-terminal component 6 is unevenly distributed on the copper foil pads 1a and 1b, the center line of the two-terminal component 6 and the center line in the left and right direction of the copper foil pads 1a and 1b are moved closer to each other. The intermediate point of the component 6 and the intermediate points of the left and right copper foil pads 1a and 1b are moved closer to each other.

Other Embodiments In the above description, the corner portions inside the square portions 34 of the pair of copper foil pads 1a and 1b are perpendicular, but the corner portions are chamfered to prevent the copper foil pads from peeling off. Alternatively, arc processing can be performed. It is also possible to perform a process of overcoating the solder resist film and holding the corner portion.
In the above description, the wiring patterns 2a and 2b are connected to the third trapezoidal portion 33 of the copper foil pads 1a and 1b, and the solder resist films 7a and 7b prevent the molten solder from flowing out. However, it is important to take care that the solder heat is evenly distributed between the left and right copper foil pads. For example, two pieces of copper solder pads 1a and 1b in FIG. It is also possible to connect a wiring pattern and apply a solder resist film.
Furthermore, if a slight vibration is given to the printed wiring board 10 when performing solder connection, the effect of self-alignment due to surface tension can be enhanced.

In relation to claim 1, the embodiment of the present invention has the following specific configuration.
The printed wiring board according to the present invention is
In order to solder the two-terminal components 4, 5, 6 to a metal foil pad composed of a pair of left and right copper foil pads 1 a, 1 b attached to the surface of the printed circuit board 10, the copper foil pads 1 a, 1 b A surface-mount printed wiring board 10 provided with a pair of solder pastes 3a and 3b to be applied to the surface of a metal foil pad comprising:
The planar shape of the pair of solder pastes 3a and 3b before heating and melting is a rectangular portion 30 having a predetermined length dimension L0 and a width dimension W0b, a first trapezoidal portion 31 having a first height dimension L1, The second trapezoidal portion 32 having the second height dimension L2 has an integrated octagonal shape.
The distance L13a between the outer ends of the rectangular portions 30 of the pair of solder pastes 3a and 3b is not less than the dimension between the end faces of the rectangular electrodes 6a and 6b of the longest two-terminal component 6 in the two-terminal components 4, 5, and 6. ,
The distance L13b between the inner ends of the rectangular portions 30 of the pair of solder pastes 3a and 3b is set to be not more than the dimension between the end faces of the rectangular electrodes 5a and 5b of the shortest two-terminal component 5 in the two-terminal components 4, 5, and 6. Yes.
Further, the two-terminal parts 4, 5, 6 are provided with a pair of rectangular electrodes 4a, 4b, 5a, 5b, 6a, 6b including fluctuations in individual dimensions of the parts, and a metal comprising the pair of copper foil pads 1a, 1b. The width dimension W0a of the foil pad is equal to or larger than the width dimension of the rectangular electrodes 6a and 6b having the maximum width dimension in the two-terminal parts 4, 5, and 6, and the rectangular portion 30 of the pair of solder pastes 3a and 3b. The width dimension W0b is a dimension equal to or less than the width dimension W0a of the metal foil pad formed of the pair of copper foil pads 1a and 1b.
As described above, in relation to the first aspect of the present invention, it is possible to surely cope with the deviation in the width direction, solder more reliably, and from the width direction dimension of the solder paste and the metal foil pad. Since the width direction dimension of the metal foil pad to be formed is specified, it is possible to surely cope with the displacement in the width direction, and there is an effect that soldering can be performed more reliably.
In relation to claim 1, the embodiment of the present invention has the following specific configuration and operational effects.
Each of the metal foil pads composed of the pair of copper foil pads 1a and 1b has a rectangular portion 34 having an area larger than the area including the square portion 30 and the second trapezoidal portion 32 of the pair of solder pastes 3a and 3b. And a third trapezoidal portion 33 corresponding to the first trapezoidal portion 31 of the pair of solder pastes 3a and 3b.
As described above, in connection with the first aspect of the present invention, the pair of copper foil pads includes the square portion of the pair of solder pastes, the square portion corresponding to the second trapezoidal portion, and the first trapezoidal portions of the pair of solder pastes. It is comprised by the 3rd trapezoid part corresponding to.
Accordingly, the solder paste in the second trapezoidal portion heated and melted flows out over the entire rectangular portion of the copper foil pad and solders the entire rectangular electrode of the two-terminal component, and the two-terminal component and the two-terminal component due to the outflow of excessive solder. There is a feature that solder balls can be prevented from being generated with the printed wiring board.
In addition, when a large number of two-terminal parts are arranged and soldered in multiple rows, the combination of metal foil pads made of the correct copper foil pads can be easily visually identified, facilitating manual operations such as analysis and rework. There is a characteristic.

In relation to claim 2 , the embodiment of the present invention has the following specific configuration and operational effects.
Solder resist films 7a and 7b are coated on the wiring patterns 2a and 2b connected to the copper foil pads 1a and 1b,
The molten solder does not flow out from the periphery of the solder pastes 3a and 3b to the wiring patterns 2a and 2b.
As described above, in relation to claim 2 of the present invention, the solder resist film is applied so that the molten solder does not flow out to the wiring pattern connected to the copper foil pad.
Therefore, it is possible to prevent the generation of a component force that tends to be unevenly distributed on the side of one copper foil pad due to the surface tension acting on the molten solder of the two-terminal component to be soldered, and the wiring pattern drawing position and drawing direction There is a feature that can be done freely.

In relation to claim 3 , the embodiment of the present invention has the following specific configuration and operational effects.
The end face of one square electrode 5b of the minimum two-terminal component 5 having the minimum length and minimum width of the two-terminal components 4, 5, 6 is the first trapezoid of the one solder paste 3b. When in contact with the inclined portion of the portion 31, the other rectangular electrode 5a of the minimum two-terminal component 5 is in contact with the trapezoidal head of the second trapezoidal portion 32 of the other solder paste 3a.
As described above, in relation to the third aspect of the present invention, even when the two-terminal component having the minimum dimension is unevenly mounted on one solder paste side, the other rectangular electrode of the two-terminal component is the other The height dimension of the second trapezoidal part is determined so as to be able to reach the solder paste.
Therefore, even in two-terminal components of the minimum dimension envisaged to approximate to the center positions of the left and right by the centripetal action of the molten solder surface tension, has the characteristic that can be reliably soldered to a pair of copper foil pads .

In relation to claim 4 , the embodiment of the present invention has the following specific configuration and operational effects.
The height dimensions L1 and L2 of the first and second trapezoidal portions 31 and 32 have different values,
The inclination angle θ1 of the inclined portion of the first trapezoidal portion 31 is large and the height dimension L1 is small,
The inclination angle θ2 of the inclined portion of the second trapezoidal portion 32 is small and the height dimension L2 is large.
As described above, in relation to the fourth aspect of the present invention, the height of the first trapezoidal portion of the solder paste is lower than the height of the second trapezoidal portion.
Therefore, when the two-terminal component is long, the size of the square electrode that protrudes outside the square portion of the solder paste is suppressed, and the square electrode that is unevenly distributed due to the surface tension of the molten solder is removed from the center line of the left and right copper foil pads. There is a feature that can be moved in the direction.

  1a and 1b Copper foil pads (metal foil pads), 2a and 2b wiring patterns, 3a and 3b solder paste, 3A and 3B metal mask openings, 4 2-terminal parts (standard size), 4a and 4b rectangular electrodes, 5 2 Terminal parts (minimum size), 5a and 5b square electrodes, 62 terminal parts (maximum size), 6a and 6b square electrodes, 7a and 7b Solder resist film, 10 Printed wiring board, 30 Square part, 31 First trapezoid part , 32 second trapezoidal portion, 33 third trapezoidal portion, 34 rectangular portion, length dimension of L0 rectangular portion 30, L1 height dimension of first trapezoidal portion 31, L2 height of second trapezoidal portion 32 Dimensions, L13a Outer spacing between a pair of square portions 30, L13b Inner spacing between a pair of square portions 30, W0a Width dimensions of a copper foil pad, W0b Width dimensions of a rectangular portion 30.

Claims (4)

A pair of metal foil pads formed on the surface of the printed wiring board for soldering a two-terminal component having a pair of electrodes, and a pair of solder pastes applied to the surface of the metal foil pad are provided, and the solder A printed wiring board for surface mounting in which paste is heated and melted,
The planar shape of the pair of solder pastes before heating and melting is a rectangular portion having a predetermined length and width, and a first trapezoid portion having a first height dimension outside the rectangular portion, The second trapezoidal portion having the second height dimension inside the rectangular portion is formed in an integrated octagonal shape,
The distance between the outer ends of the square portions of the pair of solder pastes is equal to or greater than the dimension between the end faces of the rectangular electrodes of the longest two-terminal component in the two-terminal component,
The distance between the inner ends of the square portions of the pair of solder pastes is equal to or less than the dimension between the end faces of the rectangular electrodes of the shortest two-terminal component in the two-terminal component ,
The two-terminal component includes a pair of rectangular electrodes including individual variations in component dimensions, and the width dimension of the pair of metal foil pads is equal to or greater than the width dimension of the rectangular electrode having the maximum width dimension of the two-terminal components. As well as
The width dimension of the square part of the pair of solder pastes is a dimension equal to or less than the width dimension of the pair of metal foil pads,
Each of the pair of metal foil pads includes a square part having an area larger than an area including the square part and the second trapezoid part of the pair of solder pastes, and a first trapezoid part of the pair of solder pastes. Consists of corresponding third trapezoidal part
A printed wiring board characterized by that . The wiring pattern connected to the metal foil pad is coated with a solder resist film so that molten solder does not flow out from the periphery of the solder paste to the wiring pattern. printed circuit board according to 1. The end face of one rectangular electrode of the smallest two-terminal component having the smallest length dimension and the smallest width dimension of the two-terminal parts is in contact with the inclined portion of the first trapezoidal portion of the one solder paste. It is time, the printed wiring board according to claim 1, wherein the other of the rectangular electrode of the minimum two-terminal component in contact with the trapezoidal head of the second trapezoidal portion of the other of said solder paste. The height dimensions of the first and second trapezoidal portions have different values, the inclination angle of the inclined portion of the first trapezoidal portion is large and the height dimension is small, and the height of the inclined portion of the second trapezoidal portion is small. The printed wiring board according to claim 1 , wherein the inclination angle is small and the height dimension is large.

Images