JPH06140753A - Electronic circuit board - Google Patents

Abstract

PURPOSE:To eliminate a shift of a chip component and an erected chip component or to make possible a soldering of a small chip component by a method wherein the form of a land of a printed-wiring board is formed into a square to the chip component on its inside and into the form of a semicircle combined with the square on its outside. CONSTITUTION:The form of a land 1 with a solder on a chip component 5 on a printed-wiring board, which is used as an electronic circuit board, is formed into a square inscribed a semicircle therein and into the form of a semicircle combine with the square. Or the form of a land 2 with a solder is formed into a forum lacking one part of a circle. In such a way, the form of a land with a solder is formed into a form of a combination of a square and a semicircle, whereby an erected chip component subsequent to a reflow and a misalignment of a chip component can be be significantly reduced. Moreover, an irregularity in a mounting process, such as an irregularity in printing, can be well absorbed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit board aimed at improving the soldering quality of chip parts.

[0002]

2. Description of the Related Art FIGS. 3 and 4 are views showing the shape of a soldered land of a chip part of an electronic circuit. FIG. 3 shows a square shape of the soldered land 3 and FIG. The shape is circular.

Conventionally, the shape of the soldered land of the chip part of the electronic circuit has been a square or a circle as shown in FIGS.

[0004]

In recent years, small components such as 1005 chip components (width 0.5 mm, length 1.0 mm) have been mounted on electronic circuit boards by soldering.

Conventionally, the 1005 chip component is a component of a size that is very difficult to inspect by human eyes, which is the main character of the inspection. Conventionally, there is a defect when soldering a chip component of a level of 1608 chip component (width 0.8 mm, length 1.6 mm), that is, misalignment, chip component standing (one side of the chip component is lifted up), etc. In the soldering process for parts, the problem has been highlighted more greatly.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide an electronic circuit board in which there is no misalignment or chip component standing or little soldering when soldering chip components. And

[0007]

In order to achieve the above object, the electronic circuit board of the present invention has a land shape of a printed wiring board to be soldered which is a square inside the chip part and a semicircle outside the chip part. It has a united shape.

[0008]

In the present invention, it has been found that by forming the land shape with solder into a shape combining a square and a semicircle, the chip component standing after the reflow and the chip component displacement are significantly reduced.

[0009]

1 is a plan view showing the shape of a soldering land of a chip component in a printed wiring board as an electronic circuit board according to an embodiment of the present invention, the shape being a square with a semicircle inscribed therein. And a half circle are combined. Also,
FIG. 2 is a plan view showing another shape of the soldered land, which is a shape in which a part of a circle is cut out.

In FIGS. 1 and 2, reference numerals 1 and 2 denote soldering lands, respectively.

Now, in the soldering land of the printed wiring board as shown in FIGS. 1, 2 and 3, 1005 of the shape shown in FIG.
The chip parts were reflow soldered. In FIG.
Reference numeral 5 is a chip component, and 5a is a soldering electrode for this chip component.

Soldering is performed with a metal mask of 150 μt, and a circular eutectic solder paste having a diameter of 0.5 mm is printed on each soldering land of the printed wiring board with time-temperature characteristics shown in FIG. The chips were deviated 0.2 mm forward and backward or left and right, and 4,000 chips each were mounted.

The results are shown in FIG. FIG. 7 is a diagram showing the probability of occurrence of defective products when each of the soldering lands 1, 2, and 3 is displaced 0.2 mm in the front and back and 0.2 mm in the left and right to solder 4000 chip parts. . As can be seen from the results of FIG. 7, the soldered land shape according to the present embodiment (particularly FIG. 1) shows favorable results in any item, and it is understood that the land shape is excellent.

[0014]

As described above, the chip part soldering land shape of the present invention is a mode in which variations in the mounting process such as mount deviation or printing variations are well absorbed as compared with the conventional shape. I understand.

The existence of defective soldered parts having a probability of 42/4000 of the conventional example as the resistance and capacitance of the chip parts used on the order of several hundreds on one electronic circuit board is a very large value, Therefore, the improvement of the soldering quality of the electronic circuit board of the present invention is remarkable.

[Brief description of drawings]

FIG. 1 is a plan view showing the shape of a soldered land of a chip component in a printed wiring board as an electronic circuit board that is an embodiment of the present invention.

FIG. 2 is a plan view showing another shape of the land with solder.

FIG. 3 is a view showing a shape (square) of a conventional soldered land.

FIG. 4 is a view showing a shape (circular shape) of a conventional land with solder.

5A and 5B are a side sectional view and a plan view showing a chip part used in an example of the present invention.

FIG. 6 is a diagram showing time-temperature characteristics when the soldering of the present invention is performed.

FIG. 7 is a diagram comparing results of soldering of chip components when the present invention is implemented.

[Explanation of symbols]

 1,2,3,4 Solder land 5 Chip parts 5a Solder electrodes for chip parts

Claims (1)

[Claims] 1. In an electronic circuit board for soldering a plurality of chip components having a pair of soldered electrodes to a printed wiring board, the land shape of the printed wiring board to be soldered is rectangular inside the chip components and outside thereof. An electronic circuit board having a shape in which semicircles are united with each other.