JP2004006454A - Land construction of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the land construction of a substrate for definitely mounting electronic parts or the like on the substrate. <P>SOLUTION: If a land 2 is formed to mount a predetermined circuit wiring pattern and the electronic parts or the like on an insulation base material 5 or the substrate where a surface protective layer 3 having an opening 4 for the land 2 at a predetermined position on the circuit wiring pattern is formed is constructed, the opening 4 is formed so as to allow a part of the land 2 to be exposed and the land 2 is constructed so as to allow a hole 1 to be formed on the inside of the opening 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a land structure of a circuit board for securely mounting electronic components and the like on the circuit board.
[0002]
[Conventional technology and its problems]
On the circuit board, to form lands for mounting electronic components, etc., copper foil is etched, or copper or other lands are formed by an additive method, and a cover film is opened and bonded to the lands. It is common to form a surface protective layer by the above method.
[0003]
In order to mount electronic components, it is desirable that both lands have the same size such as dimensions and shapes. However, as electronic components and lands are miniaturized, the effect of the displacement of the opening position of the surface protection layer such as a cover film is reduced. Is a serious problem.
[0004]
In addition, when the bonding accuracy of the cover film is insufficient, it is necessary to adopt another method having a higher land forming position accuracy, for example, use of a photo cover or a photoresist, which may cause a cost increase. Has become.
[0005]
Here, cream solder is printed on the land where the opening position of the cover film is misaligned, and after that, when electronic components are mounted and reflowed, defects such as generation of solder balls, insufficient solder fillets, excessive fillets or chip standing Is more likely to occur.
[0006]
In order to solve such a problem, it is possible to attach a cover film having an opening larger than the outer dimensions of the land so that the displacement of the cover film does not affect the land size. In this method, since there are few portions where the land is pressed by the cover film, land peeling is apt to occur, and in particular, environmental resistance is lowered, which is not preferable.
[0007]
[Means for Solving the Problems]
Therefore, in the present invention, a circuit wiring pattern and a land for mounting components are formed on the insulating base material, and a predetermined portion of the land for the land is formed on the circuit wiring pattern. In a circuit board provided with a surface protective layer having an opening, the opening is formed so as to expose a part of the land, and the land is provided with a hole inside the opening. A structure is provided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a view showing a land structure of a circuit board according to one embodiment of the present invention, wherein 2 is a land for mounting components, and a land 2 for both positive and negative electrodes of an electronic component is on an insulating base material. Are formed opposite to each other. Reference numeral 3 denotes a surface protection layer formed of a cover film formed by bonding an insulating film of polyimide or the like with an adhesive or the like, and reference numeral 4 denotes an opening formed in the surface protection layer 3. The opening 4 is formed such that three sides of the land 2 are pressed by the surface protection layer 3.
[0009]
On the lands 2, elongated holes 1 are formed on three sides located outside the lands 2 and inside the openings 4 of the surface protection layer 3 so as not to cover the surface protection layer 3. I have.
[0010]
According to such a land structure, both lands 2 can have the same shape and the same dimensions even when the formation position of the surface protection layer 3 is displaced.
[0011]
FIG. 2 is a cross-sectional configuration view of the land structure of the circuit board shown in FIG. 1, and reference numeral 5 denotes an insulating base material.
[0012]
FIG. 3 shows another embodiment of the present invention, in which holes 1 located above and below the land shape shown in FIG. 1 are deleted from the land shape shown in FIG. In the land structure shown in FIG. 3, when only the right and left shifts of the surface protection layer 3 are dealt with, the land shape can be appropriately adopted.
[0013]
【The invention's effect】
According to the land structure of the circuit board according to the present invention, since the surface protective layer is adhered so as to press the outermost portion of the land, it has an effect of adhering the surface protective layer to the land and pressing the land against the insulating base material. However, it is possible to suitably prevent the mechanical properties, particularly the land peeling.
[0014]
In addition, since the lands according to the present invention have holes, even if the surface protective layer such as a cover film is misaligned, the lands on the component mounting portion must have the same shape and the same dimensions on both lands. Can be done.
[0015]
Therefore, the amount of solder for mounting the electronic component can be evenly formed at the left and right terminals of the electronic component, and it is possible to prevent excessive solder supply to one land and to prevent heat conduction during reflow to the left and right lands. Since uniformity can be achieved, mounting-related defects such as generation of solder balls, shortage of solder fillets, excessive fillets, and chip standing can be reduced.
[Brief description of the drawings]
FIG. 1 is a plan view of a land structure of a circuit board according to an embodiment of the present invention.
FIG. 2 is a cross-sectional configuration diagram of FIG.
FIG. 3 is a plan view of a land structure of a circuit board according to another embodiment of the present invention.
[Explanation of symbols]
1 hole 2 land 3 surface protective layer 4 opening

Claims (1)

A circuit in which a circuit wiring pattern and a land for mounting components are formed on an insulating base material, and a surface protection layer having an opening for the land in a required portion is formed on the circuit wiring pattern. A land structure of a circuit board, wherein the opening is formed so as to expose a part of the land, and the land has a hole inside the opening.

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