JPH10178262A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the floating or positional deviations of parts or the occurrence of solder balls by respectively providing alignment sections which symmetrically become narrower in width toward the positions where the main bodies of surface mounting electronic parts having terminals connected to lands are set at the lands connecting the terminals of the electronic parts. SOLUTION: A pair of lands 3 are provided in a row so that the trapezoidal alignment sections of the lands 3 can be oppositely faced to each other at an interval. In the constitution of each land, the alignment section is formed in an equal-leg trapezoid having a depth which is equal to the total depth of the land 3. In addition, the top side 6 of the trapezoid is made narrower than the width of the terminal of mounted chip parts and the top side 6 and its vicinity of the equal-leg trapezoid is made to slightly get in the main body 4 area of the chip parts. In addition, the width of the bottom side 6 of the trapezoid, namely, the width of the land 3 is made nearly equal to the width of the terminal of the chip parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board on which lands for surface mounting are formed.

[0002]

2. Description of the Related Art In today's remarkable increase in packaging density,
Circuit boards with electronic components surface mounted are not uncommon. Most of the electronic components to be surface-mounted are two-terminal components and three-terminal components, but the lands to which those terminals are soldered are mostly rectangular.

[0003]

However, in the land of the conventional shape, not only the terminal portion of the electronic component,
When solder enters under the main body, the electronic component floats to a considerable extent, and the protruding solder becomes a ball and remains on the side of the component main body after mounting. It is not uncommon that the solder balls will cause problems such as short circuit of the circuit later. In addition, in the land of the conventional shape,
Since the solder is uniformly placed over a width wider than each terminal width of the electronic component, there is a problem that the positioning effect of the electronic component is small and the mounting position of each electronic component is easily shifted.

The present invention has been made in view of the above circumstances, and provides a circuit board capable of preventing the floating of components and the occurrence of solder balls during surface mounting, and further preventing the displacement during mounting (soldering). With the goal.

[0005]

A circuit board according to the present invention, which has been made to solve the above-mentioned problems, has terminals to be connected to respective lands to terminals to which terminals of surface-mounted electronic components are connected. And an alignment section whose width is symmetrically narrowed toward a position where the electronic component body is set. Even for surface mount components, there are components that are likely to float and those that are unlikely to occur, and there are components that are likely to be misaligned and those that are less likely to occur, or layouts that are likely to be misaligned and layouts that are less likely to occur.
Regarding the surface mounting lands formed on the same circuit board, those having an alignment portion and those which do not need to be provided may be appropriately selected.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a circuit board according to an embodiment of the present invention. FIG. 1 shows a land configuration for mounting a two-terminal chip component.
In this case, a pair of lands 3 and 3 are provided in alignment,
A trapezoidal alignment portion 5 is formed for each land 3 so as to be engaged with each other at intervals. In this land configuration, the alignment portions 5 of the lands 3 each have the shape of an equilateral trapezoid, and one third of the depth of the entire land 3 is set as the depth. The upper base 6 of the isosceles trapezoid is
The width of the terminal is smaller than the terminal width of the chip component to be mounted, and the vicinity of the upper base 6 of the isosceles trapezoid formed by each alignment portion 5 is set so as to slightly enter the inside of the chip component body 4 from the terminal 2 side. . Further, the width of the lower base 6, that is, the land 3, of the trapezoid is set substantially equal to the terminal width of the chip component.

With the above-described configuration, a portion where the land 3 does not exist below both sides of the terminal 2 of the chip component occurs. Therefore, the solder 7 existing on the land 3 and below the chip component body 4 is formed. , Spreads on both sides along the surface of the terminal 2, and as a result, the thickness of the solder 7 existing under the chip component body 4 is inevitably reduced.
And the generation of the solder balls 8 can be prevented. In addition, the upper base 6 of an equal leg trapezoid formed by each alignment unit 5.
Since the vicinity is set so as to slightly enter the inside of the chip component body 4 from the terminal 2 side, the action of the molten solder on the land 3 causes the electronic component body 4 to move in the direction in which the alignment portion 5 faces. Is set at the center of the region sandwiched between the lands 3, and the width of the lands 3 is set to be substantially equal to the terminal width of the chip component 1. In addition, a positioning action to pull the position of each terminal 2 of the electronic component 1 toward the center of the land 3 in a direction perpendicular to the direction in which the alignment portion 5 faces also occurs, and the mounted chip component 1 tilts or shifts. Can be prevented.

FIG. 2 shows a land configuration for mounting a mini-mold three-terminal component. In this case, the three lands 3a, 3b, 3c are arranged like vertices of an isosceles triangle, and the two lands 3b, 3b, 3b, 3c arranged as both ends of the base of the isosceles triangle formed by the three lands 3a, 3b, 3c.
The alignment portions 5b and 5c of the 3c and the alignment portions 5a of the remaining one land 3a are arranged alternately in a state where they face each other. Similarly to the above-mentioned chip component, the alignment portions 5a, 5b, 5 of the lands 3a, 3b, 3c are formed.
c has an equilateral trapezoidal shape and is provided at a depth of about one third of the depth of the entire land 3.
The vicinity of the upper base 6 of the isosceles trapezoid formed by 5b and 5c is set so as to slightly enter the inside of the component body 4 from the terminal 2 side. The upper bases 6, 6, 6 of the lands 3a, 3b, 3c are almost exactly aligned with the positional relationship of the terminals 2a, 2b, 2c of the mini-mold three-terminal component 1, and The length of each of the terminals 6 and 6 is set substantially equal to or slightly larger than the width of each of the terminals 2a, 2b and 2c in the mini-mold three-terminal part 1.

With the land 3 configured as described above, unnecessary solder existing on the land 3 and below the component body 4 is reduced as in the case of the chip component. As a result, the component body 4 Inevitably, the thickness of the solder 9 existing underneath is reduced, so that the floating of the component 1 and the generation of solder balls can be suppressed. In addition, the vicinity of the upper base 6 of the equilateral trapezoidal shape formed by each alignment portion 5 is set so as to slightly enter the inside of the component body 4 from the terminal 2 side. In the direction in which the electronic components 6 face each other (arrow Y in FIG. 7), a positioning operation is performed in which the electronic component main body 4 is set to the center of the region sandwiched between the lands 3a, 3b, 3c.

Further, the upper bottoms 6, 6, 6 of the lands 3a, 3b, 3c are almost exactly aligned with the positional relationship of the terminals 2a, 2b, 2c of the mini-mold three-terminal component 1, and Since the lengths of the upper bases 6, 6, 6 are set substantially equal to the widths of the terminals 2a, 2b, 2c in the minimold three-terminal part 1, the alignment portion 5a is formed by the action of the molten solder tension. And the alignment unit 5b,
The direction perpendicular to the direction in which 5c faces (arrow X in FIG. 7)
There is also a positioning action for pulling the terminals 2a, 2b, 2c of the electronic component 1 to the upper bottom positions of the alignment portions 5a, 5b, 5c, thereby preventing the mounted electronic component 1 from tilting or shifting on a horizontal plane. Is what you can do.

The alignment section may be provided on a land for mounting a four-terminal component or a surface-mounting electronic component having more terminals, but in any case, the alignment section is provided with an electronic component. It must be provided facing the main body. Also, in the above description, the depth of the alignment portion was set to about one third of the depth of the entire terminal. However, focusing on the property that the molten solder tends to be spherical, the terminal is placed on the land. It is assumed that the lands have an approximately equal aspect ratio such that a necessary and sufficient amount of solder is placed on the solder joint between the lands and the solders are protruded in a spherical shape. This is an example of a mode in which the outer edge of the narrowed portion can be formed in a shape close to the outer edge of the raised portion of the solder. In other words, the outer edge of the land including the alignment portion is selected from the simplest shapes among those determined so as to inscribe a circle as close as possible to a perfect circle. If the number of constituent sides is increased, the proportion occupied by the alignment portion having a small width may slightly increase. This shape is also a means for suppressing waste of solder.

As described above, various shapes of the alignment portion are conceivable. However, in order to obtain a positioning effect by combining the narrow terminal 2 of the mini-mold three-terminal component 1 and the land 3 wider than that, it is necessary to mount the solder. High part (top 6) and low part (on both sides of top 6)
It can be said that an isosceles trapezoid that can clarify is one of the most desirable shapes.

In the above-described embodiment, in particular, in the case of a two-terminal electronic component having terminals formed at both ends of the electronic component body, such as the chip component, the amount of solder placed on the land is uneven in position. It is necessary to provide a symmetrical alignment section with respect to the central axis along the terminal arrangement direction of the electronic component body on the land for mounting components, since it is easy to tilt up and down. Even in electronic components, the same phenomenon occurs even if the degree (lightness) varies, so that it is desirable that the electronic components have as symmetrical shapes as possible. Further, as the symmetric shape, it is conceivable to form the land in a convex shape. In the two-terminal chip component, since the width of the land is set substantially equal to the width of the terminal, a predetermined effect of reducing the amount of solder accumulated below the terminal is achieved. In this case, since the width of the terminal is sufficiently smaller than the width of the land, the existence of the protruding portions on both sides of the convex shape is sparse, which is not practical.

The land structure of the circuit pattern formed on the surface layer of the circuit board, which is the feature of the circuit board according to the present invention, is a single-layer circuit board except for a so-called flexible board. It can be applied to most existing circuit boards such as multilayer circuit boards, synthetic resin circuit boards, ceramic circuit boards, circuit boards with conductive metal patterns and circuit boards with conductive paint patterns. There is also a method for manufacturing the circuit board by appropriately selecting an insulating substrate, forming a circuit pattern by etching a conductive metal foil, forming a circuit pattern by printing and firing a conductive paint, and laminating the substrate by press-bonding or build-up. A conventional method such as the method may be used.

[0015]

As described above, when the circuit board according to the present invention is used, it is possible to prevent the floating of the electronic components and the generation of balls by soldering, and also to prevent the dislocation of the mounted electronic components from being disturbed. Therefore, many causes of troubles such as short-circuiting of the circuit and contact between the electronic components can be eliminated, thereby contributing to improvement of the reliability of the electronic circuit and the electronic device.

[Brief description of the drawings]

FIG. 1 is a plan view showing a land formed on a circuit board according to the present invention.

FIG. 2 is a plan view showing lands formed on a circuit board according to the present invention.

FIG. 3 is a side view showing a mounting state on a land formed on a circuit board according to the present invention.

FIG. 4 is a side view showing a mounting state on a land formed on a conventional circuit board.

FIG. 5 is a side view showing a mounting state on a land formed on a circuit board according to the present invention.

FIG. 6 is a side view showing a mounting state on a land formed on a conventional circuit board.

FIG. 7 is a plan view showing a positional relationship between lands formed on a circuit board according to the present invention and electronic components.

[Description of Signs] 1 component 2 terminal 3 land 4 component body 5 alignment unit

Claims (1)

[Claims] 1. A terminal (2) of a surface mounting electronic component (1).
, The width of which is narrowed symmetrically toward a position where an electronic component body (4) having a terminal (2) connected to each land (3) is set on a land (3) to which the land is connected. A circuit board provided with each part (5).