WO2021235196A1

WO2021235196A1 - Mounting structure for chip component

Info

Publication number: WO2021235196A1
Application number: PCT/JP2021/016755
Authority: WO
Inventors: 幸男小谷
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2020-05-21
Filing date: 2021-04-27
Publication date: 2021-11-25
Also published as: JPWO2021235196A1; CN115553074A; TW202145849A

Abstract

A mounting structure for a chip component according to the present disclosure is a mounting structure for a chip component in which both terminal electrodes of a miniature SMD component 2 are soldered to two lands 3 on a print wiring board 1. The size of the miniature SMD component 2 is 0.6mm × 0.3mm, and the dimension between the two lands 3 is 0.23-0.25mm.

Description

Mounting structure of chip parts

This disclosure relates to the mounting structure of chip components.

Conventionally, the flow soldering method and the reflow soldering method are well known as methods for mounting electronic components on a printed wiring board.

Patent Document 1 discloses a flow soldering method. The printed wiring board used in this flow soldering method corresponds to a board in which various circuit elements are surfaced and a hole is formed in which a lead terminal of a lead component is inserted, and a board is opened. It is composed of a peelable sheet member having an opening formed at a position where the solder is formed. Then, an adhesive layer having adhesiveness is formed at a predetermined position other than the substrate electrode formed on the substrate, and the surface on which the adhesive layer is formed is covered with the sheet member.

Patent Document 2 discloses a reflow soldering method. The mounting structure of this reflow soldering method is a mounting structure of a chip component formed by soldering terminal electrodes at both ends of the chip component to two lands on a printed wiring board. In this mounting structure, the two lands formed on the printed wiring board are a conductor film in which a part of the circular opposite side is cut off and the two cut-out sides face each other in parallel. It is a thing.

Japanese Unexamined Patent Publication No. 8-116153 JP-A-2007-194462

The present disclosure provides a chip component mounting structure that enables stable bond printing on a printed wiring board and mounting arrangement of small chip components.

The mounting structure of the chip component in the present disclosure is a mounting structure of the chip component in which both terminal electrodes of the chip component are soldered to two lands on the printed wiring board in the flow soldering process. The chip component is a small SMD component of 0.6 mm × 0.3 mm, and the dimension between the two lands is 0.23 mm or more and 0.25 mm or less.

The mounting structure of the chip component in the present disclosure is a printed wiring on which a small SMD (Surface Mounted Device) component (for example, 0.6 mm × 0.3 mm (0603 size)), which is a chip component, is mounted, which was not possible in the past. Stable bond printing can be performed on the board. This makes it possible to mount and arrange small SMD components. By defining the dimensions between the two lands, it is possible to eliminate bond printing defects and eliminate the dropout of small SMD parts during flow soldering work.

FIG. 1 is a plan view showing a mounting structure of a chip component according to an embodiment. FIG. 2 is a plan view showing a mounting structure of other chip components in the embodiment.

(Findings, etc. that form the basis of this disclosure)
At the time when the inventors came up with this disclosure, the flow soldering method was extremely productive.

With the recent miniaturization of SMD components (surface mount components), the size of SMD components mounted on printed wiring boards has also been miniaturized. As an example, the surface area of the SMD component is about 1/2 size, from 1.0 mm × 0.5 mm (1005 size) to 0.6 mm × 0.3 mm (0603 size).

In the flow soldering method, the size limit of SMD parts that can be flow soldered is 1.0 mm x 0.5 mm, and the number of small SMD parts that cannot be mounted by the flow soldering method is increasing.

A major problem in mounting a small SMD component with an SMD component size of 0.6 mm × 0.3 mm by the flow soldering method is that it is extremely difficult to perform stable bond printing on the printed wiring board. .. This is because the component size is small, so it is not possible to secure the land size and the distance between lands where bond printing can be performed on the lower part of the SMD component.

Even if bond printing can be performed, the bond amount (adhesive force) cannot be secured, and the target small SMD parts may come off due to the solder jet in the flow tank during flow soldering work. Further, due to the displacement of the bond printing position, soldering defects such as red eyes and solder bridges may occur even if soldering is performed in the flow tank. The inventors have discovered a problem that it is difficult to ensure the quality of the substrate when mounting such a small SMD component by the flow soldering method, and have come to construct the subject of the present disclosure in order to solve the problem. rice field.

Therefore, the present disclosure provides a chip component mounting structure that enables stable bond printing on a printed wiring board and mounting and placement of small chip components.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations for substantially the same configuration may be omitted. This is to prevent the following explanation from becoming unnecessarily redundant and to facilitate the understanding of those skilled in the art.

It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment)
Hereinafter, embodiments will be described with reference to FIGS. 1 and 2.

[1-1. composition]
FIG. 1 is a plan view showing a mounting structure of a chip component according to an embodiment. FIG. 1 shows a mounting structure of a small SMD component 2 which is a chip component having a size of 0.6 mm × 0.3 mm. The mounting structure shown in FIG. 1 is an example in which the small SMD component 2 is mounted in a shape that conforms to the land shape, and the solder resist has an NSMD (Non Solder Mask Defined) structure that partially conforms to the land shape. An example is shown.

Two lands 3 on which the small SMD component 2 is mounted are formed on the printed wiring board 1. The dimension t1 between the insides of the two lands 3 is set to 0.23 mm or more and 0.25 mm or less. The dimension t2 of the portion of the land 3 on which the small SMD component 2 is mounted is set to 0.2 mm, and the width dimension t3 is set to 0.3 mm. The longitudinal dimension t4 of each of the two lands 3 is set to 0.65 mm or more and 1.2 mm or less. The direction of the width dimension t3 referred to here coincides with the lateral direction of the small SMD component 2. Further, the direction of the longitudinal dimension t4 coincides with the longitudinal direction of the small SMD component 2.

The dimension t1 is set to 0.23 mm or more and 0.25 mm or less, but if the dimension t1 is smaller than 0.23 mm, printing such that a bond is applied on the land 3 due to a deviation in bond printing or the like is printed. There is a problem that mistakes occur. Further, if the dimension t1 is smaller than 0.23 mm, there is a problem that a solder bridge is generated between the terminal electrodes at both ends of the small SMD component 2 during soldering. Further, if the dimension t1 is larger than 0.25 mm, there is a problem that the terminal electrode of the small SMD component 2 and the land 3 are not soldered due to the misalignment when the component is mounted, and there is a high possibility that a soldering error occurs. The above problem can be solved by setting the dimension t1 to 0.23 mm or more and 0.25 mm or less.

Further, the longitudinal dimension t4 of each of the two lands 3 is set to 0.65 mm or more and 1.2 mm or less, but in the case of a small SMD component 2 having a size of 0.6 mm × 0.3 mm, soldering is performed. Since the land 3 is very small, if the longitudinal dimension t4 is smaller than 0.65 mm, moisture gas may be generated between the substrate and the solder when performing the flow soldering work, which may hinder soldering. There's a problem. The above problem can be solved by setting the longitudinal dimension t4 to 0.65 mm or more and 1.2 mm or less. Further, by setting the longitudinal dimension t4 to 1.2 mm or less, the small SMD component 2 can be mounted on the printed wiring board 1 at a high density.

Further, in the other three directions of each land 3, a convex portion 4a for drawing in a circuit pattern 4 connected to a GND pattern, a power supply pattern circuit, or the like is provided. The convex portion 4a includes a copper foil. That is, the land 3 has the convex portion 4a. The circuit pattern 4 connected to the land 3 is connected via the convex portion 4a along the shape of the convex portion 4a. In the present embodiment, three convex portions 4a are provided, but at least one may be provided. In other words, the convex portion 4a may be provided at the position where the circuit pattern 4 of the land 3 is connected (the lead-in portion of the circuit pattern 4).

A solder resist 5 is formed around the land 3 and the circuit pattern 4. The solder resist 5 is an insulating printing (resist ink) portion, and when the pattern is pulled in, the soldered portion of the land 3 is prevented from becoming abnormally large.

Bond printing is performed between the insides of the two lands 3, and the small SMD component 2 is placed on the bond printing to temporarily fix the small SMD component 2. The bond printing may be performed using a metal mask or a dispenser device.

After that, turn the printed wiring board upside down again, and if there are irregularly shaped electronic parts, mount the parts by hand or use a robot mounting machine. Then, by performing the flow soldering work, the printed wiring board 1 and the mounted small SMD component 2 are soldered and electrically energized.

FIG. 2 is a plan view showing a mounting structure of other chip components in the embodiment. FIG. 2 shows a mounting structure of a small SMD component 2 having an SMD component size of 0.6 mm × 0.3 mm. In the mounting structure shown in FIG. 2, the pattern drawn into each of the two lands 3 indicates the wiring of the solid pattern 6. A thermal pattern (cross-shaped pattern) is formed by connecting the solid pattern 6 to the lead-in pattern of the circuit pattern 4. That is, in the mounting structure shown in FIG. 2, the land 3 has at least two convex portions 4a. A solid pattern 6 connected only to at least two convex portions 4a is provided on the printed wiring board 1. The solid pattern 6 is connected along the shape of each of the convex portions 4a of at least two convex portions 4a.

By doing so, it is possible to make the land size of the two lands 3 not significantly changed, and to suppress the amount of heat applied to the lands 3, that is, to keep the temperatures of the two lands 3 the same. Can be done. Then, it is possible to prevent the parts from being displaced, the parts from being cracked, and the like.

[1-2. Effect, etc.]
As described above, in the present embodiment, the mounting structure of the chip component is the mounting of the chip component in which both terminal electrodes of the small SMD component 2 are soldered to the two lands 3 on the printed wiring board 1 in the flow soldering process. It is a structure. The small SMD component has a size of 0.6 mm × 0.3 mm, and the dimension between the two lands 3 is 023 mm or more and 0.25 mm or less.

As a result, stable bond printing can be performed on the printed wiring board 1, which was not possible in the past, and the small SMD component 2 can be mounted and arranged. By defining the dimensions between the two lands 3, it is possible to eliminate bond printing defects and eliminate the dropout of the small SMD component 2 during flow soldering work.

By defining the dimension between the two lands 3 as 0.23 mm to 0.25 mm, it is possible to eliminate bond printing defects and eliminate the dropout of small SMD parts during flow soldering work.

The lengthwise dimension of the land 3 is 0.65 mm or more and 1.2 mm or less.

As a result, by defining the dimensions of the land 3 in the longitudinal direction, it is possible to improve the solder contact and solder wettability during the flow soldering operation.

Further, the mounting structure of the chip component is a shape that can draw the pattern to the land or a solid pattern in the mounting structure of the chip component in which the terminal electrodes at both ends of the chip component are soldered to the two lands on the printed wiring board 1. The shape will be a thermal land.

As a result, the stress on the small SMD component 2 mounted due to the expansion and contraction of the printed wiring board 1 is relaxed by performing pattern wiring along the pattern pulling shape to the convex portion for pulling into the two lands 3. It becomes possible to eliminate the destruction of parts. Further, when the solid pattern 6 is pulled in, the pattern wiring along the shape of the convex portion 4a becomes a thermal land, and it is possible to stabilize the amount of solder during the flow soldering work. The quality of soldering can be improved.

Further, the land 3 has a convex portion 4a. Then, the circuit pattern 4 connected to the land 3 is connected via the convex portion 4a along the shape of the convex portion 4a.

Further, the land 3 has at least two convex portions 4a. A solid pattern connected only to at least two convex portions 4a is provided on the printed wiring board 1. The solid pattern 6 is connected along the shape of each of the convex portions 4a of at least two convex portions 4a.

(Other embodiments)
As described above, embodiments have been described as an example of the techniques disclosed in this application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. have been made.

Therefore, other embodiments will be exemplified below.

The present invention is not limited to the above example, and the shape of the chip component may be any shape. Further, the land, the pattern, and the resist shape may be, for example, a shape with an R or a pattern arrangement only at a place where the pattern is actually drawn. The feature is that it is possible to solder to two lands with the same amount of solder during flow soldering, and it is possible to make the stress on the terminals at both ends of the chip component the same due to the expansion and contraction of the printed wiring board. ing.

Since the above-described embodiment is for exemplifying the technology in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the equivalent thereof.

The mounting structure of the chip parts in the present disclosure makes it possible to improve productivity and realize low-cost production costs, which are the characteristics of the flow soldering method, and is applicable to various electric appliances.

1 Printed wiring board 2 Small SMD parts (chip parts)
3 Land 4 Circuit pattern 4a Convex part 5 Solder mask 6 Solid pattern

Claims

In the mounting structure of a chip component in which both terminal electrodes of the chip component are soldered to two lands on the printed wiring board in the flow soldering process.
The chip component is a small SMD component having a size of 0.6 mm × 0.3 mm.
A chip component mounting structure in which the dimension between the two lands is 0.23 mm or more and 0.25 mm or less.
The mounting structure for a chip component according to claim 1, wherein the dimension of the land in the longitudinal direction is 0.65 mm or more and 1.2 mm or less.
In the mounting structure of the chip component in which the terminal electrodes at both ends of the chip component are soldered to the two lands on the printed wiring board, the shape is such that the pattern can be drawn into the land or the shape becomes a thermal land when the solid pattern is formed. The mounting structure of the chip component according to Item 1 or 2.
The land has a convex portion and has a convex portion.
The mounting structure of a chip component according to claim 1 or 2, wherein the circuit pattern connected to the land is connected via the convex portion along the shape of the convex portion.
The land has at least two protrusions and has at least two protrusions.
A solid pattern connected only to the at least two convex portions is provided on the printed wiring board, and the solid pattern is connected along the shape of each convex portion of the at least two convex portions. The mounting structure of the chip component according to claim 1 or 2.