JPH11195867A - Printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high insulation between solders on adjacent connection pads, and to achieve peel strength between solder of solder balls of electronic components and connection pads and between connection pads and pattern wiring. To prevent the occurrence of connection failure between the electronic component and the printed circuit wiring board. SOLUTION: A mounting surface 45 on which a surface mount type electronic component 43 is mounted, a first pad portion 46, and second pad portions 47a, 4 protruding outward from the first pad portion 46.
7b, and a resist film is formed over the second pad portions 47a and 47b of each connection pad 42 and the surface of the insulating base such that the peripheral side surface of the first pad portion 46 is exposed. 49 are formed, and the second pad portions 47a and 47b are pressed on the surface of the insulating base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a BGA (Ball Gri
d Array type electronic components and CSP (Chip Scale Package)
Also, the present invention relates to a mounting structure of a printed circuit wiring board to which surface mount electronic components such as a chip size package electronic component are connected by a reflow soldering method.

[0002]

2. Description of the Related Art In recent years, as a mounting form of an electronic component such as an LSI package, a surface mounting type called a flat package has become mainstream. As this surface-mounted electronic component, an LSI bare chip is mounted on a printed circuit wiring board (also called a printed wiring board) and sealed, and spherical array terminals called solder balls are formed on the back surface of the board. A BGA type and a CSP type in which a spherical array terminal similar to the BGA is formed on the back surface of a package having substantially the same dimensions as a bare chip are well known.

[0003] Such a BGA type electronic component and CSP
When the electronic components are mounted on the printed circuit board, the solder balls on the back of the package and the connection pads on the printed circuit board are connected by reflow soldering in a state where they face each other. In a so-called collapsed portion, which is a fusion bonding portion with the electronic component, an electronic component and a printed circuit wiring board, for example, 2
Mechanical stress and thermal stress are generated due to natural temperature cooling and shrinkage of the plastic mold from the state where the temperature is raised and heated in the reflow heating temperature atmosphere of about 35 ° C., so that the electronic component and the printed circuit wiring board are not connected. Connection failure may occur.

FIG. 11 is a plan view showing a mounting surface 2 of a conventional printed circuit wiring board 1. On the back surface of the electronic component 3 which is a BGA type electronic component or a CSP type electronic component, as described above, the spherical solder balls are formed in a two-dimensional matrix, for example, at predetermined terminal pitches ΔL1 and ΔL2 in the vertical and horizontal directions. The terminal pitches ΔL1 and ΔL2 are selected to be relatively large values, such as 1.5 mm or 1.27 mm, for a BGA type electronic component, as compared with a CSP type electronic component described later. In the case of a CSP type electronic component, for example, 0.
The value is selected to be relatively small, such as 8 mm, 0.65 mm, 0.5 mm, or 0.4 mm, as compared with the above-mentioned BGA type electronic component.

[0005] A plurality of connection pads 4 are formed on the mounting surface 2 of the printed circuit wiring board 1 on which the electronic component 3 is mounted at the same interval according to the terminal pitches ΔL1 and ΔL2 of the electronic component 3. . The planar shape of each connection pad 4 is, for example, circular, and a part of the plurality of connection pads 4 is connected to the pattern wiring 5 on the insulating base material 8. A resist film 6 is formed on the surface 8a of the insulating base material 8 on which the connection pads 4 and the pattern wirings 5 are formed so as to expose the connection pads 4 and cover the pattern wirings 5.

FIG. 12 is an enlarged plan view showing the vicinity of the connection pad 4 of the printed circuit wiring board 1 shown in FIG.
FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. The land diameter D1 of the connection pad 4 is BGA
In the case of mounting electronic components, for example, D1 =
0.8 to 1.0 mm, and when mounting a CSP type electronic component, the land diameter D for the BGA type electronic component.
Even smaller than 1, for example D1 = 0.3-0.8
mm. The thickness T1 of the connection pad 4 is BG
Regardless of whether an A-type electronic component or a CSP-type electronic component is mounted, T1 is about 20 to 40 μm.

The connection pad 4 has a circular shape having the land diameter D1 as described above, and a resist film 6 having the same thickness is formed around the connection pad 4. This resist film 6
Contact is made over substantially the entire circumference of the cylindrical outer peripheral surface 7 of the connection pad 4, and covers the surface 8 a of the insulating base material 8 exposed between the adjacent connection pads 4. It prevents adhesion to the surface 8a of the base material 8.

FIG. 14 is an enlarged cross-sectional view of a part of another conventional printed circuit wiring board 11. This prior art is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 9-1350069.
In this conventional technique, a solder ball of an electronic component 12 to be mounted is heated and melted and deformed as shown in FIG. 1 to form a collapse 13, which is connected to a connection pad 15 on a pattern wiring 14. A resist film 18 is formed over the peripheral portion 16 of the connection pad 15 and the surface 22a of the insulating base material 22. The electronic component 12 is a BGA type electronic component. A concave portion 19 is formed by the resist film 18 corresponding to the position of the solder ball, and the connection pad 15 is formed on the bottom surface of the concave portion 19. The distance ΔT1 between the back surface 20 of the electronic component 12 where the solder balls are provided and the surface 22a of the concave portion 19 is set to an appropriate value for preventing the flow of the molten solder, and the short circuit and the insulation failure between the adjacent connection pads 15 are reduced. It is configured to avoid.

Specifically, the diameter of the solder ball is 0.5 m
m, the height from the back surface 20 is 0.46 mm, and the pitch is 1.
When a 0 mm BGA type electronic component is mounted, the diameter D2 of the pattern wiring 14 of the printed circuit wiring board 11 is 0.4 m.
m, the diameter D3 of the connection pad 15 is 0.8 mm, the thickness of the connection pad 15 is 0.06 mm, the thickness of the resist film 18 is 0.12 mm, and the diameter D4 of the concave portion 19 is 0.6 mm.
Even when the electronic component 12 is displaced from the mounting position, when the solder ball is melted by heating, the melted solder stays in the recess 19 and is prevented from flowing out to the adjacent connection pad 15. .

FIG. 15 is an enlarged plan view of a part of another conventional printed circuit wiring board 25. This prior art is disclosed, for example, in Japanese Patent Application Laid-Open No. 5-304353. In this prior art, a land 27 which is an elliptical connection pad is formed on a surface 26a of an insulating base material 26, a hole 28 is formed in the center thereof, and both ends in the short-axis direction in the horizontal direction in FIG. The protruding part 29 with a sharp tip
a, 29b are formed. Such protrusions 29a, 2
9b, the protrusions 29a, 29
The molten solder invades the surface of the land 27, and the angle between the outer surface of the solder and the surface of the land 27 is reduced, so that a solder bridge is formed between the adjacent lands 27 without reducing the peel strength of the land 27. It is configured to prevent such a situation.

[0011]

Problems to be Solved by the Invention FIGS.
In the prior art shown in FIG. 1, after the electronic component 3 is mounted on the printed circuit board 1, the molten solder balls of the electronic component 3 are easily peeled off from the connection pads 4 due to the generation of mechanical stress and thermal stress. Since the printed circuit board 4 is easily peeled off from the insulating base material 8, there is a problem that a connection failure between the printed circuit board 1 and the electronic component 3 occurs.

In another conventional technique shown in FIG.
Since the peripheral portion 16 of the connection pad 15 is pressed by the resist film 18, the connection pad 15 is prevented from being separated from the pattern wiring 14 by the mechanical stress and the thermal stress, but the collapse 13 has a large peel strength. In order to be joined to the connection pad 15, the bottom surface 20 of the connection pad 15 must be exposed in the recess 19 with a large area. On the other hand, since the wiring pattern of each pattern wiring 14 is determined according to the terminal pitch of the solder balls of the electronic component 12, the space Δ
L2 becomes small, and as a result, there is a problem that the distance ΔL3 between the adjacent collapses 13 becomes small and a solder bridge is easily formed. Conversely, in order to increase the distance ΔL3 between the adjacent collapses 13 so that a solder bridge is not formed, it is necessary to reduce the diameter D2 of the bottom surface 21, and in this case, the peel strength decreases. The contradictory problem arises.

In another conventional technique shown in FIG. 15, the protrusions 29a and 29b are provided at both ends of the connection pad 27 in the short axis direction.
Is formed, but the solder also flows into the projections 29a and 29b, and the solder on the adjacent connection pads 27 comes close to each other.
There is a problem that insulation properties are reduced.

An object of the present invention is to achieve high insulation between solders on adjacent connection pads, and to achieve peel strength between the solder of the solder bridge of the electronic component and the connection pads and between the connection pads and the pattern wiring. It is an object of the present invention to provide a printed circuit board capable of preventing the occurrence of connection failure between an electronic component and a printed circuit board.

[0015]

According to a first aspect of the present invention, there is provided a method for mounting a surface mount type electronic component on a mounting surface.
A plurality of connection pads having a pad portion and a second pad portion protruding outward from the first pad portion are formed, and a second side of each connection pad is exposed such that a peripheral side surface of the first pad portion is exposed. A printed circuit board, wherein a resist film is formed over a pad portion and a surface of an insulating base material.

According to the present invention, the connection pad has its first
A second pad portion protruding from the pad portion is formed, and a resist film is formed over the second pad portion and the surface of the insulating base material, so that a large peel strength is achieved between the connection pad and the printed circuit wiring board. can do. Further, since the peripheral side surface of the connection pad is formed so as to be exposed from the resist film, the molten solder of the solder ball of the electronic component which has been heated and melted at the time of mounting adheres from the surface of the first pad portion to the peripheral side surface. And the occurrence of connection failure between the electronic component and the printed circuit board can be prevented. In particular, in the present invention, unlike the related art of FIG. 14, the peripheral portion of the connection pad is not pressed by the resist film over the entire periphery, so that the bonding area between the first pad portion and the solder is not reduced, and Adheres to the peripheral side surface of the first pad portion, so that the bonding area increases as compared with the prior art, improving insulation between solders on adjacent connection pads, and printing with electronic components due to mechanical stress and thermal stress. Poor connection with the circuit wiring board can be prevented.

According to a second aspect of the present invention, the resist film is formed over a middle position between a base end and a free end of the second pad portion connected to the first pad portion and a surface of the insulating base material. It is characterized by that.

According to the present invention, the area between the base end of the second pad portion connected to the first pad portion and the free end portion, which is closer to the free end portion than the intermediate position between the free end portion and the surface of the insulating base material. Since the resist film is formed, the molten solder is prevented from intruding from the first pad portion to the free end portion from the base end portion of the second pad portion beyond the halfway position, whereby the adjacent connection is prevented. The insulation between the solders on the pads can be improved.

[0019]

FIG. 1 is a plan view showing a printed circuit board 41 according to an embodiment of the present invention. FIG. 2 is an enlarged view of a connection pad 42 of the printed circuit board 41 shown in FIG. FIG. 3 is a bottom view showing the structure of the back surface 44 of the electronic component 43 mounted on the printed circuit wiring board 41, and FIG. 4 is a side view of the electronic component 43 viewed from above in FIG. It is.

The printed circuit wiring board 41 of the present embodiment has a mounting surface 45 on which a BGA type electronic component (hereinafter simply referred to as electronic component) 43 which is a surface mount type electronic component is mounted.
In addition, a plurality of connection pads 42 having a circular first pad portion 46 and a pair of second pad portions 47a and 47b protruding radially outward from the first pad portion 46,
The predetermined intervals are set to ΔL3 and ΔL4 in the vertical and horizontal directions in a dimensional matrix.
With the opening, for example, formed by a printing method,
A resist film 49 is formed over the second pad portions 47 a and 47 b of each connection pad 42 and the surface 65 a of the insulating base material 65 so that the peripheral side surface 48 of the first pad portion 46 is exposed.

The electronic component 43 is formed by mounting a bare chip of a semiconductor element such as an LSI on a printed circuit wiring board and sealing it, and a plurality of solder balls 50 are formed in a two-dimensional matrix on the back surface 44 of the board. The vertical and horizontal pitches of the solder balls 50 are the same as the pitches ΔL3 and ΔL4 of the connection pads 42 of the printed circuit board 41.

In the present embodiment, the printed circuit wiring board 4
1, a copper-clad laminate with a Cu foil is used as an insulating base material 65, a via hole is formed in the insulating base material 65 by drilling, and the substrate surface 65a and the inner surface of the via hole are collectively plated with Cu. The copper clad laminate has a Cu foil thickness of 18
μm, and the Cu plating thickness is selected to be about 10 μm to 20 μm. Therefore, a Cu conductive layer in which a Cu plating layer is adhered to the surface of a Cu foil is formed on the surface 65a of the insulating base material 65, and its thickness is set to 30 μm to 40 μm.
The wiring pattern is etched on the copper-clad laminate thus formed, and the pattern wiring 51 is formed.

On the substrate on which the pattern wiring 51 is formed as described above, the connection pad 42 and the resist film 4 are formed.
9 is formed and used as a printed circuit wiring board 41. The pattern wiring 51 of the printed circuit wiring board 41
Is formed as a mounting surface 45.

FIG. 5 is a sectional view taken along line VV of FIG. 2, FIG. 6 is a sectional view taken along line VI-VI of FIG. 2, and FIG. Second pad part 4
FIG. 7 is a partial perspective view showing a state in which 7a and 47b are pressed by a resist film 49. In the connection pad 42, the diameter D11 of the first pad portion 46 is 0.4 mm, and each of the second pad portions 47a and 47b is radially outward in the diameter direction from the outer peripheral portion of the first pad portion 46, respectively. The projection lengths L3 and L4 are 0.1.
mm. The widths B1 and B2 of the second pad portions 47a and 47b in the vertical direction in FIG. 2 are selected to be 0.1 mm.

The resist film 49 is formed on the second pad portion 4.
7a, 47b, the base end portion 52 connected to the first pad portion 46
The second pad portions 47a and 47b are formed over a region 54 closer to the free end portion 53 than a middle position between the free end portions 53 and the surface 65a of the insulating base material 65.
Pressed with. The peripheral side surface 48 of the first pad portion 46 is composed of a pair of arc surfaces 56a, 56b extending in an arc in the circumferential direction on both sides of each of the second pad portions 47a, 47b. Each of the arc surfaces 56a, 56b has a respective second pad portion 47a, 47
The two side surfaces 57a, 57b; 58a, 58b exposed from the resist film 49 excluding the region 54b of FIG. Further, the inner peripheral surface 61 of the resist film 49 is formed with the respective arc surfaces 56a, 56b.
And are formed at substantially constant intervals radially outward from the side surfaces 57a, 57b; 58a, 58b.

Thus, the inner diameter D1 of the resist film 49 is
A pair of semicircular voids 62a and 62b are formed between the inner peripheral surface 61 of 2 = 0.5 mm and the connection pad 42,
Each solder ball 50 melts and flows into each of the gaps 62a and 62b by the reflow heating when the electronic component 43 is mounted, and the arc surfaces 56a and 56b of the first pad portion 46 and the side surface 57a of the second pad portions 47a and 47b. , 57
b; attached to 58a, 58b and electrically connected. The molten solder is also applied to the upper surface 63 of the first pad portion 46 and the upper surfaces 64a, 64 of the second pad portions 47a, 47b.
b, and the peel strength between the solder ball 50 and the connection pad 42 is improved.

Also, as described above, each second pad portion 47
Since a and 47b are pressed by the resist film 49 in the region 54 near the free end 53, the peel strength between the connection pad 42 and the surface 65a of the insulating base material 65 is improved. In the present embodiment, a pair of second pad portions 47a and 47b are formed so as to protrude from the first solder pad portion 46, and the regions 54 of the second pad portions 47a and 47b on the free end 53 side are formed in the present embodiment. In FIG. 14, the resist film 49 is used to hold about 0.05 mm, that is, about L3 / 2 or L4 / 2, so that the peripheral portion 16 of the connection pad 15 extends over the entire circumference in the circumferential direction as in the prior art shown in FIG. Compared to the configuration pressed by the resist film 18,
The pitch between the connection pads 42 can be reduced,
Thereby, the density of the wiring pattern can be increased.

The printed circuit board 41 as described above can be manufactured as follows. That is, a land is formed by fixing copper or a conductive material as a base at the position where the connection pad 42 is to be formed, and a via hole is formed at the center position of the land by drilling, and the substrate surface 65a and the inner surface of the via hole are made of copper or the conductive material. Plated with
Unnecessary portions of the plating pattern are dissolved and removed by etching to form connection pads 42 and pattern wirings 51.
To form After that, the resist film 49 is surface-treated with a heat-resistant coating material in a range in which solder is not to be attached. Using a liquid photo-solder resist having high finishing accuracy, gaps 62 a and 62 are provided between the connection pad 42 and the resist film 49.
b is formed.

The procedure for manufacturing such a substrate is only one method, and it may be manufactured by various different procedures.

FIG. 8 is an enlarged plan view showing the vicinity of a connection pad 42 provided on a printed circuit wiring board according to another embodiment of the present invention. The mounting surface 4 on which the same electronic components 43 as described above are mounted on the printed circuit wiring board of the present embodiment.
5, a circular first pad portion 67, and four second pad portions 68 a, 68 b, projecting radially outward from the first pad portion 67 at intervals of 90 ° in the circumferential direction.
A plurality of connection pads 42a having 68c and 68d are formed. Four arc surfaces 69a of the first pad portion 67,
A peripheral side surface 74 having 69b, 69c, 69d, and a pair of side surfaces 70a, 70a,
70a; 71a, 71b; 72a, 72b; 73a, 7
3b so that the second connection pads 42a are exposed.
A resist film 75 is formed over the pad portions 68a to 68d and the surface of the insulating base material.

With such a configuration, the space between the inner peripheral surface 76 of the resist film 75 and the peripheral side surface 74 of the connection pad 42a is divided for each of the second pad portions 68a to 68d.
Two voids 76a, 76b, 76c, 76d are formed. The molten solder of the solder ball 50 of the electronic component 43 flows into and adheres to these gaps 76a to 76d at the time of mounting, as in the embodiment shown in FIGS.
The peel strength between the solder ball 50 and the connection pad 42a is improved, and the peel strength of the connection pad 42a to the insulating base material is improved. The peel strength of the connection pad 42a with respect to the insulating base material is equal to the four second pad portions 68a-68.
68 g are provided and are pressed by the resist film 75, so that a greater strength can be achieved.

Further, in the present embodiment, the resist film 7
5 is a region 89 on the free end portion 80 side of the intermediate portion between the base end portion 79 and the free end portion 80 connected to the first pad portion 67 of each of the second pad portions 68a to 68d; And formed over. Thereby, the electronic component 43
And a land shape having an optimum size for mounting the semiconductor device, and arc-shaped voids 76a, 76b, 76c, and 76b separated by the second pad portions 68a to 68d between the first pad portion 67 and the resist film 75. Solder flows into 76d and the first and second pad portions 67, 68a to 68d
Arc surfaces 69a to 69d and respective side surfaces 70a, 70b;
71a, 71b; 72a, 72b; 73a, 73b, and the peel strength between the solder and the connection pad 42a can be improved. Particularly, in the present embodiment, since the four second pad portions 68a to 68d are formed, the mechanical stress and the thermal stress generated in the collapse of the solder are dispersed in four directions to act on the second pad portions 68a to 68d. The peeling force can be reduced, thereby reducing each second
The amount h of the pad portions 68a to 68d protruding radially outward from the first pad portion 67 can be reduced to reduce the distance between adjacent connection pads, thereby increasing the terminal pitch.

As still another embodiment of the present invention, as shown in a plan view of FIG.
Instead of 2a, a first pad portion 81 having a square planar shape
And a connection pad 42b having a pair of second pad portions 82a and 82b formed on both opposing side portions so as to protrude outward.

As still another embodiment of the present invention, as shown by virtual lines 83a and 83b in FIG.
In addition to the second pad portions 82a and 82b, second pad portions may be formed on the other side portions.
Also in this embodiment, the same effects as those of the embodiments shown in FIGS. 1 to 8 can be achieved.

As another embodiment of the present invention, as shown in a plan view of FIG. 10, a first pad portion 85 having an elliptical planar shape, and both ends of the first pad portion 85 in the major axis direction. A pair of second pad portions 86 projecting outward from the second pad portions 86
a and 86b are connected to the connection pad 42c shown in FIGS.
Connection pads 42, 42a, 42 of the respective embodiments shown in FIG.
It may be used instead of b. Also in this case, the same effects as those of the embodiments shown in FIGS. 1 to 9 can be achieved.

Further, as another embodiment of the present invention, as shown by imaginary lines 87a and 87b in FIG. 10, second elliptical first pad portions 85 project outward from both ends in the short axis direction of the first pad portions 85. A pad portion may be formed in addition to the second pad portions 86a and 86b projecting outward from both ends in the long axis direction.

As still another embodiment of the present invention, the second pad portions 86 at both ends in the longitudinal direction in FIG.
A connection pad in which only the second pad portions 87a and 87b at both ends in the short axis direction may be used without forming the a and 86b.

In each of the embodiments shown in FIGS. 1 to 10 described above, a pair of second pad portions are formed on the first pad portion at 180 ° intervals in the circumferential direction, or 90 ° in the circumferential direction.
Although the configuration in which the four second pad portions are formed at intervals of every ° has been described, as still another embodiment of the present invention, the planar shape of the first pad portion is not limited to the above, and the first pad portion is not limited to the above. The position and shape where the two pad portions are formed with respect to the first pad portion are not limited to the above, and can be appropriately changed according to the wiring pattern without departing from the present invention.

[0039]

According to the first aspect of the present invention, since the second pad portion is pressed by the resist film so that the peripheral side surface of the first pad portion is exposed, the degree of freedom of the wiring pattern is greatly limited. High insulation between the connection pads can be obtained without any trouble, the peel strength between the solder of the solder balls of the electronic component and the connection pad and between the connection pad and the pattern wiring can be improved, and the electronic component and the printing It is possible to prevent the occurrence of connection failure with the circuit wiring board.

According to the second aspect of the present invention, since the free end portion of the second pad portion is pressed by the resist film with respect to the intermediate position thereof, it is optimal for mounting the surface mount electronic component on the first pad portion. A large land shape can be obtained, and the molten solder adheres to the surface of the second pad portion that is not covered with the resist film and is connected to the second pad portion, so that even higher peel strength can be realized. .

[Brief description of the drawings]

FIG. 1 shows a printed circuit board 41 according to an embodiment of the present invention.
FIG.

FIG. 2 is an enlarged plan view showing a connection pad 42 of the printed circuit wiring board 41 shown in FIG.

FIG. 3 is a bottom view showing the structure of the back surface 44 of the electronic component 43 mounted on the printed circuit wiring board.

FIG. 4 is a side view of the electronic component 43 as viewed from above in FIG.

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 2;

FIG. 6 is a sectional view taken along section line VI-VI in FIG. 2;

FIG. 7 shows second pad portions 47a and 47 of the connection pad 42.
FIG. 9 is a partial perspective view showing a state where b is pressed by a resist film 49;

FIG. 8 is an enlarged plan view showing the vicinity of a connection pad 42a provided on a printed circuit wiring board according to another embodiment of the present invention.

FIG. 9 is an enlarged plan view showing the vicinity of a connection pad 42b provided on a printed circuit wiring board according to still another embodiment of the present invention.

FIG. 10 is an enlarged plan view showing the vicinity of a connection pad 42c provided on a printed circuit wiring board according to still another embodiment of the present invention.

FIG. 11 is a plan view showing a mounting surface 2 of a conventional printed circuit wiring board 1.

FIG. 12 is an enlarged plan view showing a connection pad 4 of the printed circuit wiring board 1 shown in FIG.

FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. 12;

FIG. 14 is an enlarged sectional view of a part of another conventional printed circuit wiring board 11;

FIG. 15 shows another prior art printed circuit wiring board 25;
3 is an enlarged plan view of a part of FIG.

[Explanation of symbols]

41 Printed circuit wiring board 42, 42a, 42b, 42c Connection pad 43 Electronic component 44 Back surface 45 Mounting surface 46, 67 81, 85 First pad portion 47a, 47b; 68a to 68d; 82a, 82b;
6a, 86b Second pad portion 48 Peripheral side surface 49, 75 Resist film 50 Solder ball 51 Pattern wiring 52 Base end 53 Free end 54 Area

Claims (2)

[Claims] A plurality of connection pads having a first pad portion and a second pad portion protruding outward from the first pad portion are formed on a mounting surface on which the surface mount electronic component is mounted; A printed circuit board, wherein a resist film is formed over a second pad portion of each connection pad and a surface of an insulating base material such that a peripheral side surface of the first pad portion is exposed. 2. The method according to claim 1, wherein the resist film is formed over a middle position between a base end and a free end of the second pad portion connected to the first pad portion and a surface of the insulating base material. Item 2. The printed circuit wiring board according to Item 1.