JPH0459119B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a highly reliable double-sided printed wiring board in which component mounting holes are formed by punching. BACKGROUND OF THE INVENTION Recent printed wiring boards have a remarkable increase in the number of component mounting holes as electronic devices become more densely packaged. Composite laminates, in which component mounting holes can be formed by punching, are attracting attention as insulating substrates in place of glass cloth-based epoxy resin laminates, which require only drilling to form component mounting holes. When conducting printed circuits on both sides of an insulating board using through holes,
Currently, through holes formed by punching are less reliable than those formed by drilling.
Therefore, through holes are formed by drilling, and component mounting holes are formed by punching. Problems to be Solved by the Invention However, when forming component mounting holes by punching, double-sided printed wiring boards are more likely to cause delamination around the mounting holes on the insulating substrate than normal single-sided printed wiring boards. However, there is a problem in that the peel strength of the land portion where the component mounting hole is provided is significantly deteriorated. In view of the above points, the present invention provides the following features when forming component mounting holes by punching on a double-sided printed circuit board.
The purpose is to prevent delamination around holes in the insulating substrate and deterioration of peel strength in land areas. Means for Solving the Problems In order to achieve the above object, the present invention provides a method for forming component mounting holes penetrating land portions in a double-sided printed circuit board by punching, the land forming surface of an insulating substrate. An isolated land with a size larger than the die hole diameter of the punching mold is formed on the opposite side, and the isolated land is placed so as to cover the die hole, and a hole for mounting the component is provided by punching. It is characterized by Effects As a result of a detailed study of the causes of delamination of layers around component mounting holes on insulating substrates and deterioration of beer strength in land areas, the following findings were obtained. That is,
In the conventional punching process, as shown in FIG. 2, due to the thickness of the circuit 4 formed by etching, the surface of the insulating substrate 3 does not come into close contact with the surface of the die 5 of the punching mold, and is placed over the die hole. There is a pause. Therefore, when punching a component mounting hole through the insulating substrate 3 at the land 2 for mounting the component, the effect of the clearance between the punch 1 and the die 5 is not reflected, resulting in delamination and deterioration of peel strength. I found out that this happens. In the present invention, as shown in FIG.
An isolated land 6 having a size larger than the hole diameter of the die 5 is formed on a surface opposite to the surface on which the land 2 is formed, and the isolated land 6 is arranged so as to cover the hole of the die 5. Therefore, there is no gap between the hole of the die 5 and the insulating substrate 3, and the punching process can be performed satisfactorily. The dimensions of the isolated land should be at least the diameter of the die hole in the mold, but are preferably 0.2 mm larger than the diameter of the die hole in the mold.
It is better if it is larger in mm and smaller than the component mounting land.
If the dimension of the isolated land is less than the diameter of the die hole of the mold, the isolated land will enter the die hole during punching and will be ineffective. Furthermore, in order to perform high-density mounting, it is better for the isolated land to be smaller than the component mounting land. Examples Examples of the present invention will be described below. Examples 1 to 3, Comparative Example 1 After cutting a 1.6 mm thick double-sided copper-clad laminate (composite laminate made by Shin-Kobe Electric, trade name E-665) to the work size, through-holes were made by drilling, and then the through-holes were drilled. The walls were plated to provide continuity. Thereafter, through a process of circuit formation by printing and etching, isolated lands of various diameters shown in Table 1 were formed on the opposite side of the 2φ component mounting land. Using a punching die with a punch diameter of 1.00φ and a die diameter of 1.07φ, the punching die was arranged as shown in FIG. 1, and the outer shape was punched out at the same time as the holes for mounting the parts, to obtain a double-sided through-hole printed wiring board. Comparative Example 2 After cutting a 1.6 mm thick single-sided copper-clad laminate (composite laminate made by Shin-Kobe Electric, trade name E-565) to the work size, a 2φ component mounting land was formed through the same circuit formation process as in the example. Formed. Using a mold with a punch diameter of 1.00φ and a die diameter of 1.07φ, the die was arranged as shown in FIG. 2, and the outer shape was punched out simultaneously with holes for mounting parts, thereby obtaining a single-sided printed wiring board. Appearance of component mounting holes and component mounting land (2φ) for printed wiring boards obtained in Examples and Comparative Examples
The results of evaluating the peel strength are shown in Table 1.

[Table] Evaluation criteria ○: No delamination
△: Slight delamination
×: Effect of the invention with delamination As is clear from Table 1, according to the present invention, a double-sided printed wiring board that suppresses delamination around component mounting holes during punching and maintains sufficient land peel strength is produced. It can be manufactured and its industrial value is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the state of punching of a component mounting hole in the present invention, and FIG. 2 is a cross-sectional view showing a state of punching of a conventional component mounting hole. 1 is a punch, 2 is a land, 3 is an insulating substrate, 4 is a circuit, 5 is a die, and 6 is an isolated land.

Claims (1)

[Claims] 1 In a method of etching metal foil pasted on both sides of an insulating substrate into a predetermined shape to form circuit and component mounting lands, and punching out component mounting holes that penetrate through the land portions, A double-sided device characterized in that an isolated land having a size larger than the die hole diameter of the punching mold is formed on the surface, the isolated land is arranged to cover the die hole, and a part mounting hole is provided by punching. Manufacturing method for printed wiring boards.