JPH06350243A - Printed wiring board - Google Patents

Abstract

PURPOSE:To provide a printed wiring board having such structure as requiring no modification of pattern by providing the printed wiring board with soldering lands corresponding to large and small electrodes. CONSTITUTION:A surface mounting component, e.g. a diode, is soldered onto a printed wiring board 5. A land 2 is soldered to the cathode electrode of a surface mounting diode 11. When the surface mounting diode 11 has a large anode electrode 12, both lands 1a, 1b are soldered whereas when the diode 11 has a small anode electrode 12', only the land 1a is soldered. Consequently, two types of component can be soldered and mounted positively without requiring any modification of the land pattern on the printed wiring board 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a printed wiring board for mounting components, which is mainly called a printed circuit board, and particularly when a chip type element having different electrode sizes is soldered to the surface. And a printed wiring board having

[0002]

2. Description of the Related Art Conventionally, an element (or SMD) of a surface mount component such as a chip type on a printed wiring board such as a printed circuit board.
When soldering, form an insulating film called a green mask on the upper surface of the wiring printed on the substrate, expose only the soldering part (land) of the wiring terminal, and place solder on that part Place the element and solder it. The performance of these chip elements improves year by year,
It has the same function but is becoming smaller. If the board is completed by designing electronic parts that use the board and some changes are made due to trial production, or if a new product, SMD, appears and is to be replaced, the size of the part will change. Since it may be different, there was no way to correct the change other than redesigning the pattern of the board. Therefore, even if a slight change is made, it is necessary to redo all the production of the board, which causes a problem of enormous correction time and cost. Since this is a great obstacle to the completion of the product, there is a demand for a substrate that can be easily and quickly changed, or a method for avoiding the change.

Therefore, a printed wiring board has been proposed in which lands for a large element and a land for a small element are provided in the same component mounting electrode portion so as to be able to cope with a change in the component (Nippon Denso Publication). Technique 78-005). This is based on not only the size of the device to be mounted, but also the size of the device expected, and the lands that will be the electrodes in advance are used for large devices in distant regions and for small devices in close regions. The green mask is left uncovered against and.

[0004]

However, in the land of this system, if there is a difference in the shape and size of the electrodes of the surface mount component, the land should be provided in accordance with the wide electrode such as a large element. Is required and is later changed to a small electrode for a small element, or in the case of a small electrode such as a new alternative product, if this small electrode is soldered to the land, the solder will be the element. The surface tension of the molten solder acts on the land that is not covered by the electrode, causing the small element to move to the larger land side, causing other electrodes to separate from the land, or the electrodes contacting both lands. Then, a problem such as short circuit occurs. Therefore, an object of the present invention is to avoid the change of the substrate and to make the change promptly and efficiently by devising the structure of the land so that it can be surely mounted even if the size of the electrode of the element is changed. It is in.

[0005]

In order to solve the above problems, the structure of the present invention is a printed wiring board in which soldering lands corresponding to surface mounting type elements having different sizes are formed in the same element region. In the soldering land, a land for one electrode is soldered together with the first land for a small electrode of an element and a large land for another element together with the first land. The second land portion is formed separately.

[0006]

When the electrode of the element is large, it is soldered to the outer and inner lands, and when the electrode of the element is small, it is soldered only to the inner land. Since the outer land is separated, when the small electrode is soldered, the small electrode is not pulled by the large land by the surface tension of the molten solder.

[0007]

In the case of a small-sized electrode, it is not necessary to use all the lands formed for the large-sized electrode, and if only the necessary small-sized land is used, the surface tension of the molten solder of other small lands will be reduced. Almost no displacement occurs due to. In the case of soldering a large electrode, since the inner land is also used for soldering, there is an effect of effectively using the pattern while improving soldering strength. Further, since the change of parts is considered in advance, no major design change such as pattern design is required.

[0008]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a diagram schematically showing a part of a printed wiring board (printed circuit board) 5 showing an embodiment of the present invention. Of printed wiring patterns, surface mounting components such as functional elements are soldered. The electrode part is shown. The anode electrode side land 1 is divided into two regions by an insulating film called a green mask, or the pattern is completely divided (second land, third land), and a land division 3 is provided. When soldering an element component (not shown), between the cathode electrode side land (first land) 2 and the outside and inside lands (second land, third land) in the case of a large electrode, small In the case of electrodes, only the inner land (second land) is soldered. Both electrode lands 1, 2
From this, the wiring pattern 4 is routed to other required regions.

With such a land pattern, as shown in FIG.
When soldering the surface mount component 11 (here, the shape of a diode is imitated) as shown in (a),
Since the anode electrode 12 of the component is large, it is soldered over the inner region 1a and the outer region 1b of the land on the anode electrode side. On the other hand, when the anode electrode 12 'becomes smaller as in the surface mount component 11' of another shape (also imitating another diode shape) as shown in FIG. 2 (b), the land on the anode electrode side is Will be soldered only to the inner area 1a (second land).

Even when the small electrode shape is soldered to the same land area as shown in FIG. 2 (b), the solder is deposited in the area 1b, but since it does not contact the anode electrode 12, the component 11 'is During soldering, the surface tension of the molten solder does not pull the land 1b toward the land 1b, and the cathode electrode 13 does not separate from the cathode electrode side land 2.

(Second Embodiment) Further, the land division 3 of the land 1 on the anode electrode side is not completely separated as shown in FIG. 1, but a part thereof is connected to form a pattern as shown in FIG. Even if it is realized, this may be more convenient depending on the wiring pattern if there is no problem in mounting, and it can be designed according to the purpose.

As described above, the land corresponding to the large electrode side can be soldered corresponding to the large electrode and the small electrode of the element by forming the divided pattern, so that it is possible to change the design or to make a new product. Even when the element is changed to a small element or the like, the element electrode does not move to the area for the large electrode due to surface tension. In addition, it is not necessary to redesign the pattern even when changing parts, and it is possible to quickly respond to the completion of the product.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a land division shape of the present invention.

FIG. 2 is an explanatory view when soldering mounting components to the land of FIG.

FIG. 3 is an explanatory view showing a land division shape of a second embodiment.

[Explanation of symbols]

1 Anode Electrode Side Land 1a Anode Electrode Side Land (Second Land) 1b Anode Electrode Side Land (Third Land) 2 Cathode Electrode Side Land (First Land) 3 Land Division 4 Wiring Pattern 5 Printed Circuit Board 11, 11 'Surface Mount Parts (SMD, element, diode) 12, 12 'Anode electrode 13 Cathode electrode

Claims (1)

[Claims] 1. A printed wiring board in which soldering lands corresponding to surface-mounted elements of different sizes are formed in the same element region, wherein one of the soldering lands has a land corresponding to one electrode. The first land to be soldered to the small electrode of the element,
A printed wiring board formed by being divided into a second land portion to be soldered together with the first land to a large electrode in the case of another element.