JP2021174975A - Printed circuit board and printed circuit board manufacturing method - Google Patents

Abstract

To provide a printed circuit board and a manufacturing method thereof capable of preventing cream solder used for mounting a component on a pad from flowing into a through-hole via.SOLUTION: A printed circuit board 10 includes a substrate body 2 having a plurality of layers of conductor patterns 1 formed on an insulating substrate, and a surface mount component C mounted on a pad 3 provided on the substrate body 2 via a cream solder 4, and a land 6 of a through-hole via 5 formed on the substrate body 2 is covered with a solder resist 7 for preventing the inflow of the cream solder 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to a printed circuit board and a method for manufacturing a printed circuit board, which can contribute to miniaturization and an increase in component mounting density.

The techniques shown in Patent Documents 1 and 2 are known as this type of printed circuit board.
The printed wiring board shown in Patent Document 1 includes a plurality of layers of conductor patterns formed on an insulating substrate and a plurality of plated through holes formed through the insulating substrate and conducting different conductor patterns.
The plated through holes are arranged near the pads of the conductor pattern in which the connectors are mounted by soldering, and the upper surface thereof is covered with an insulating layer made of a silk printing layer.
Further, in this printed wiring board, a solder resist layer is further laminated on the insulating layer made of the silk printed layer at the peripheral edge of the opening of the plated through hole.
Then, in such a solder resist layer, by covering the peripheral portion of the opening of the plating through hole provided in the vicinity of the pad, a short circuit of the wiring due to solder residue, a solder ball, or the like is prevented.

In the motherboard of an electronic device shown in Patent Document 2, a through hole land on the upper surface side provided close to an electrode pad on which a SOP (Small Outline Package) or a chip component is mounted has an SMD (Solder Mask Defined) structure. There is.
In such a motherboard, the through-hole land is almost covered with an insulating film, so that even if the solder scatters during reflow or flow, the solder bridge or solder between the electrode pad and the through-hole land, and between the through-hole lands The occurrence of short circuits can be reduced or prevented.

Japanese Unexamined Patent Publication No. 09-116271 Japanese Unexamined Patent Publication No. 2013-258330

The printed circuit boards shown in Patent Documents 1 and 2 have a configuration for preventing a short circuit of wiring due to solder residue or the like when solder is scattered by covering the peripheral edge of the opening of the through hole.
However, such measures are limited, and for example, when cream solder is used when mounting parts, the cream solder may flow into the through hole and lead to a big trouble.

Specifically, in printed circuit boards as described above, surface mount components (chip types) are becoming smaller, but from the viewpoint of wiring design, the design is such that through holes are adjacent to the pads. I wasn't.
This is a result of considering the risk from the manufacturing side that the cream solder used for component mounting flows into the through hole and the solder is defective if the design is such that the pad and the through hole are close to each other.
In the future, even if the parts are further miniaturized, it is necessary to separate the through holes from the pads by a certain length in consideration of the above manufacturing risks. Therefore, for example, 1005 size to 0603 size (JIS abbreviation (mm notation)). ), The chip size can be reduced by 64%, but when the through-hole vias and patterns are included, it can be reduced by only 21%, and the wiring pattern length is also improved by about 10%.

In other words, conventional printed circuit boards have not fully enjoyed the benefits of component downsizing, and it is necessary to change the current wiring standards and bring the pads and through-holes closer together to further improve the efficiency of the mounting area. It has become.
Furthermore, if through holes are created in close proximity to the pads, there is a risk that the cream solder applied to the pads will flow into the through holes in the reflow process, causing solder defects. It's not easy.

The present invention has been made in view of the above circumstances, and can prevent cream solder used for mounting components on a pad on a substrate from flowing into through holes, and at the same time, have a high density of components. Provided are a printed circuit board that can be mounted and a method for manufacturing a printed circuit board.

In order to solve the above problems, the present invention proposes the following means.
In the printed circuit board shown in the first aspect of the present invention, a substrate body having a plurality of layers of conductor patterns formed on an insulating substrate and a surface mount component mounted on a pad provided on the substrate body via cream solder. The through-hole via land formed on the substrate body is covered with a solder resist for preventing the inflow of the cream solder.

In the method for manufacturing a printed circuit board shown in the second aspect of the present invention, the printed circuit board is mounted on a substrate body having a plurality of layers of conductor patterns formed on an insulating substrate and a pad provided on the substrate body via cream solder. The printed circuit board including the surface mount component is characterized by having a resist step of coating the lands of through-hole vias formed on the substrate body with a solder inflow prevention solder resist that prevents the inflow of cream solder. And.

According to the present invention, cream solder used for mounting components on a pad on a substrate is prevented from flowing into through-hole vias, which enables high-density mounting of components on a substrate.

It is a top view which shows the minimum structure which concerns on the printed circuit board of this invention. It is a top view of the printed circuit board which concerns on embodiment. It is a top view of the printed circuit board which concerns on the modification 1 of embodiment. It is a top view of the pad which concerns on the modification 2 of embodiment.

The minimum configuration according to the printed circuit board 10 of the present invention will be described with reference to FIG.
The printed circuit board 10 includes a substrate main body 2 having a conductor pattern 1 and a surface mount component C mounted on the substrate main body 2.

The substrate main body 2 has a plurality of layers of conductor patterns 1 on an insulating substrate (not shown), and FIG. 1 shows only a part of conductor patterns 1 located on the surface.
The surface mount component C is mounted on the pad 3 provided on the substrate main body 2 via the cream solder 4.

The entire land 6 of the through-hole via 5 formed on the substrate main body 2 is covered with a solder resist 7 for preventing the inflow of the cream solder 4.

According to the printed circuit board 10 of the present invention described above, the land 6 of the through-hole via 5 formed on the substrate main body 2 is covered with the solder resist 7 for preventing the inflow of the cream solder 4.
As a result, in the printed circuit board 10, when the cream solder 4 used for mounting the components on the pad 3 on the printed circuit board 10 is reflowed, the cream solder 4 is prevented from flowing into the through-hole via 5. be able to.
As a result, in the printed circuit board 10, the through-hole via 5 and the surface mount component C can be arranged at close positions, and the component can be mounted on the substrate at a high density.

(Embodiment)
The printed circuit board 100 according to the embodiment of the present invention will be described with reference to FIG. 2 as viewed from the front surface side.
The printed circuit board 100 includes a substrate main body 12 having a conductor pattern wiring 11 and a surface mount component C1 mounted on the substrate main body 12.

As the surface mount component C1, a chip component or a package substrate having an electrode shape in which solder balls such as BGA (ball grid array) are arranged in a grid pattern is used.
Further, as the surface mount component C1 of this example, a surface mount component C1 formed in a rectangular shape in a plan view is used.
Further, the illustrated conductor pattern wiring 11 is located on the surface of the substrate main body 12, and only a portion connecting the surface mount component C1 and the land 16 (described later) of the through-hole via 15 is shown.

The substrate main body 12 is a laminated body having a plurality of layers of conductor pattern wiring 11 on an insulating substrate (not shown).
The surface mount component C1 is mounted on the pad 13 provided on the substrate main body 12 via the cream solder 14.
The pad 13 of this example has two pad pieces 13A for one surface mount component C1, and these two pad pieces 13A are in the length direction of the surface mount component C1 (vertical direction in the drawing). Are arranged so as to be spaced from each other.

A through-hole via 15 is formed on the substrate body 12.
The through-hole via 15 connects the conductor pattern wiring 11 laminated on the substrate main body 12 up and down, and is provided in the vicinity of the surface mount component C1.
Only two through-hole vias 15 are shown, and the other through-hole vias 15 are not shown.

The land 16 of the through-hole via 15 is coated with a solder resist 17 for preventing the inflow of the cream solder 14.
The solder resist 17 for preventing solder inflow is applied to the through-hole vias 15 and the lands 16 and their surroundings so that the cream solder 14 applied on the pads 13 of the substrate main body 12 does not flow into the through-hole vias 15.
Further, the solder resist 17 for preventing solder inflow is arranged so as to integrally cover the plurality of through-hole vias 15 and lands 16 and is arranged on the long side side of the surface mount component C1 formed in a rectangular shape in a plan view. ..
Further, the solder resist 17 for preventing the inflow of solder is provided so as to integrally cover the lands 16 of a plurality of through-hole vias 15 composed of two (or more).

Then, in such a printed circuit board 100, in the process of mounting the surface mount component C1 on the substrate body 12, the cream solder 14 flows into the through-hole via 15 in the reflow process after applying the cream solder 14 to the pad 13. Can be prevented.

Specifically, in the manufacturing process of the printed circuit board 100, the process proceeds with a drilling process, a plating process, an outer layer pattern forming process, an etching process, and a resist process (resist coating / exposure / development) of the through hole via 15 after the laminated press. .. At this time, in the resist step, the solder resist 17 is applied around the through-hole via 15 and the land 16 in the vicinity of the pad 13 as shown in FIG.
As a result, in the manufacturing process of the printed circuit board 100, the coating pattern is only changed so as to leave the solder resist 17 around the land 16 of the through-hole via 15 located near the pad 13 during the normal resist process. There is no cost increase due to the increase in.

According to the printed circuit board 100 of the present embodiment described in detail above, the land 16 of the through-hole via 15 formed on the substrate body 12 is covered with the solder resist 17 for preventing the inflow of the cream solder 14. ing.
As a result, in the printed circuit board 100, when the cream solder 14 used for mounting the components on the pad 13 on the printed circuit board 100 is reflowed, the cream solder 14 is prevented from flowing into the through-hole via 15. be able to.
As a result, in the printed circuit board 100, the through-hole via 15 and the surface mount component C1 can be arranged at close positions, and the component can be mounted on the substrate at a high density.

As a more specific effect, in the printed circuit board 100 of the present embodiment, the length of the conductor pattern wiring 11 is reduced to 2/3 of the previous length by bringing the through-hole via 15 and the surface mount component C1 closer to each other. And the inductance can be reduced to 5/8, which is almost half.
This leads to an improvement in the performance of the capacitor in the high frequency range, and when compared with the mounting area of a 0603 size chip, it can be reduced by about 25%, which can contribute to high-density mounting of the surface mount component C1. Become.

The above embodiment may be modified as follows.
[Modification 1]
The solder resist 17 for preventing solder inflow of FIG. 2 integrally covers a plurality of through-hole vias 15 and lands 16 and is arranged on the long side side of the surface mount component C1 formed in a rectangular shape in a plan view.
However, the present invention is not limited to this, and in the modified example 1, each through-hole via 15 and the land 16 are individually covered as shown in FIG. Solder resists 17 for preventing solder inflow may be arranged at the upper and lower sides in the figure). As a result, in the first modification, the through-hole via 15 and the surface mount component C1 can be brought closer to each other, and the length and inductance of the conductor pattern wiring 11 can be reduced.

[Modification 2]
In the first modification, when the through-hole vias 15 are formed on the short side (upper and lower sides in the drawing) of the surface mount component C1 as shown in FIG. 3, the solder resist 17 is applied in the immediate vicinity of the pad 13. , There is a possibility that the soldering of the surface mount component C1 will fail in the reflow process.
In that case, as shown in FIG. 4 shown as the second modification, a margin portion 13a (in this example, on the left and right sides in the drawing) on which the surface mount component C1 is not mounted is provided around the pad piece 13A constituting the pad 13. Therefore, the surface mount component C1 may be smoothly soldered in the reflow process.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within a range not deviating from the gist of the present invention are also included.

The present invention relates to a printed circuit board and a method for manufacturing a printed circuit board, which can contribute to miniaturization and an increase in mounting density.

1 Conductor pattern 2 Board body 3 Pad 4 Cream solder 5 Through-hole via 6 Land 7 Solder resist for solder inflow prevention 10 Printed circuit board 11 Conductor pattern wiring 12 Board body 13 Pad 13A Pad piece 13a Margin 14 Cream solder 15 Through-hole via 16 Land 17 Solder resist for solder inflow prevention 100 Printed circuit board C Surface mount component C1 Surface mount component

Claims (7)

A printed circuit board comprising a substrate body having a plurality of layers of conductor patterns formed on an insulating substrate, and surface mount components mounted on a pad provided on the substrate body via cream solder.
A printed circuit board characterized in that the through-hole via land formed on the substrate body is covered with a solder resist for preventing the inflow of the cream solder. The printed circuit board according to claim 1, wherein the solder resist for preventing solder inflow is provided so as to cover only one through-hole via land. The printed circuit board according to claim 1, wherein the solder resist for preventing solder inflow is provided so as to integrally cover a plurality of through-hole via lands. The surface mount component on the substrate body is formed in a rectangular shape in a plan view, and the through-hole via and the solder resist for preventing solder inflow that covers the through-hole via are arranged on the long side and / or the short side thereof. The printed circuit board according to any one of claims 1 to 3. The pad according to any one of claims 1 to 4, wherein the pad on the substrate body is formed in a relatively large shape so as to have a margin portion at the peripheral edge portion with respect to the surface mount component. Printed circuit board. In a printed circuit board including a substrate body having a plurality of layers of conductor patterns formed on an insulating substrate and a surface mount component mounted on a pad provided on the substrate body via cream solder.
A method for manufacturing a printed circuit board, which comprises a resist step of coating a land of through-hole vias formed on the substrate body with a solder resist for preventing the inflow of the cream solder. The method for manufacturing a printed circuit board according to claim 6, wherein the solder resist for preventing solder inflow is formed by changing a resist coating pattern in a resist step of forming a resist on the substrate body.

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