WO2020050330A1 - Method of applying solder paste and mask - Google Patents

Abstract

This method of applying solder paste onto an object (B) to be applied onto is provided with: a step of applying solder paste onto an application region (T) of which at least a part is positioned in a bonding region (P) of the object (B) to be applied onto, in such a way that a non-application region (N) is formed in the bonding region (P). The application region (T) includes a plurality of peripheral regions (A1) which are arranged at intervals in a circumferential direction around the center (O) of the bonding region (P).

Description

Solder paste application method and mask

The present invention relates to a method for applying a solder paste and a mask.
Priority is claimed on Japanese Patent Application No. 2018-166395 filed on September 5, 2018, the content of which is incorporated herein by reference.

Conventionally, solder paste is widely used in surface mount technology (SMT) in which electronic components such as LGA (Land Grid Array) and BGA (Ball Grid Array) are mounted on the surface of a printed circuit board or the like. The solder paste is produced by mixing a solder powder with a flux. In surface mounting, first, a solder paste is applied to a surface of a printed circuit board on which pads (electrodes) are provided. At this time, the solder paste is applied to the pad, and the application range is equal to the area of the pad. Next, the electronic component is placed on the surface of the printed board so that the pads of the printed board and the lands (electrodes) of the electronic component face each other. At this time, the solder paste is located between both electrodes of the printed circuit board and the electronic component. Finally, the printed circuit board on which the electronic components are mounted is heated (reflowed) in a reflow oven, and the solder powder of the solder paste is melted and bonded to each other, and then solidified again to electrically connect the two electrodes. , Surface mounting is completed. In order to secure an appropriate electrical connection, the resistance value of the solder connecting between the electrodes must be equal to or less than a predetermined value. Further, even if a shock or the like is applied to the printed circuit board after surface mounting, the solder is required to have a predetermined strength in order to maintain appropriate electrical connection without being damaged.

In order to apply the solder paste to the surface of a printed circuit board, for example, screen printing using a mask disclosed in Patent Document 1 is used.

JP 2001-77521 A

は ん だ Solder connecting between both electrodes after the reflow process may include so-called voids. The void is a void formed in the solder, and the void is filled with a gas obtained by vaporizing a resin component of the flux or a solvent of the flux. When a void is formed, the electrical resistance between the two electrodes increases, and there is a possibility that an appropriate electrical connection cannot be secured. In addition, the voids cause a reduction in the strength of the solder, and when an impact or the like is applied, the electrical connection between the two electrodes may not be maintained. In addition, a relatively small void may not cause such a defect, and since the void causing the above-described defect is a relatively large void, the size of the generated void is suppressed in the field of surface mounting. Is required.

The present invention has been made in view of such circumstances, and even when a void is formed in solder in surface mounting, a solder paste coating method and a mask that can suppress the size of the void. The purpose is to provide.

The present invention employs the following means in order to solve the above problems.
A first aspect of the present invention is a method of applying a solder paste to an object to be applied, wherein at least a part of the solder paste is positioned in the joint area so as to form a non-application area in the joint area of the object to be applied. Applying a solder paste to an application region to be formed, wherein the application region has a plurality of peripheral regions arranged at intervals in a circumferential direction around a center of the joining region.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged to face each other with the center of the joining region interposed therebetween.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged so as to extend in a direction intersecting the direction in which the plurality of peripheral regions oppose each other.

In the first aspect of the present invention, a gap between the plurality of peripheral regions may be 30% or more and 70% or less of a maximum diameter of the joining region.

In the first aspect of the present invention, the gap between the plurality of peripheral regions may be not less than 85.7% and not more than 200% of the width of each peripheral region in the direction facing the plurality of peripheral regions.

In the first aspect of the present invention, the number of the plurality of peripheral regions may be two to six.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged at equal intervals in the circumferential direction.

In the first aspect of the present invention, the plurality of peripheral regions include a first region and a second region having different circumferential lengths, and the first region and the second region are arranged in the circumferential direction. May be arranged alternately.

In the first aspect of the present invention, opposing sides of the plurality of peripheral regions adjacent in the circumferential direction may be parallel to each other.

In the first aspect of the present invention, the application region may further include a central region located radially inside the plurality of peripheral regions.

In the first aspect of the present invention, opposing sides of the central region and each peripheral region may be parallel to each other.

In the first aspect of the present invention, the area of the central region may be not less than 44.4% and not more than 278% of the area of each peripheral region.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged so as to partially contact each other.

In the first aspect of the present invention, the circumferential width of each peripheral region may be gradually increased from the center of the joint region toward the outside in the radial direction.

In the first aspect of the present invention, a ratio of a gap between the plurality of peripheral regions, which opens radially outward from a center of the bonding region, to a whole circumference of the bonding region is 11.5%. It may be the above.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged so as to overlap an outer edge of the joining region.

In the first aspect of the present invention, the plurality of peripheral regions may be arranged in the joining region.

According to a second aspect of the present invention, there is provided a method of applying a solder paste to an object to be applied, wherein at least a part of the solder paste is positioned in the joint region so as to form a non-application region in the joint region of the object. A step of applying a solder paste to an application area to be formed, wherein the application area includes an extension area including the center of the bonding area and extending in one direction.

In the second aspect of the present invention, the extension region may be arranged so as to overlap an outer edge of the joining region.

In the second aspect of the present invention, the extension region may be arranged in the joining region.

In the second aspect of the present invention, the application region may further include a plurality of side regions arranged so as to sandwich the extension region in a direction intersecting the longitudinal direction of the extension region.

In the second aspect of the present invention, opposing sides of the extension region and each side region may be parallel to each other.

In the second aspect of the present invention, the plurality of side regions may be arranged so as to overlap an outer edge of the joining region.

In the second aspect of the present invention, the plurality of side regions may be arranged in the joining region.

A third aspect of the present invention is a mask used in the method for applying a solder paste according to the first or second aspect, wherein an opening is formed at a position corresponding to the application region.

According to the above aspect of the present invention, even when a void is formed in the solder during surface mounting, the size of the void can be suppressed. Therefore, it is possible to secure an appropriate electrical connection between the object to be coated such as a substrate and the two electrodes of the electronic component, and to prevent a decrease in the strength of the solder connecting between the two electrodes. Etc. can be provided.

1 is a schematic diagram illustrating a solder printing apparatus according to an embodiment of the present invention. It is a top view of a substrate which is an application object concerning one embodiment of the present invention. It is a top view of the mask used for screen printing concerning one embodiment of the present invention. It is a schematic diagram showing each process of the application method of the solder paste concerning one embodiment of the present invention. FIG. 7 is a schematic view showing a step after a solder paste application step in surface mounting. FIG. 3 is a plan view showing a solder paste application region in the first embodiment. FIG. 10 is a plan view showing a solder paste application region in a second embodiment. FIG. 13 is a plan view illustrating a solder paste application region in a third embodiment. FIG. 14 is a plan view showing a solder paste application region in a fourth embodiment. FIG. 14 is a plan view showing a solder paste application region in a fifth embodiment. FIG. 15 is a plan view showing a solder paste application region in a sixth embodiment. FIG. 15 is a plan view showing a solder paste application region in a seventh embodiment. FIG. 19 is a plan view showing a solder paste application region in Example 8. FIG. 21 is a plan view showing a solder paste application region in a ninth embodiment. FIG. 21 is a plan view showing a solder paste application region in Example 10. FIG. 21 is a plan view showing a solder paste application region in an eleventh embodiment. FIG. 39 is a plan view showing a solder paste application region in Example 12. FIG. 39 is a plan view showing a solder paste application region in a thirteenth embodiment. FIG. 39 is a plan view showing a solder paste application region in Example 14. FIG. 39 is a plan view showing a solder paste application region in Example 15. FIG. 39 is a plan view showing a solder paste application region in Example 16. FIG. 39 is a plan view showing a solder paste application region in Example 17. FIG. 39 is a plan view showing a solder paste application region in Example 18. FIG. 39 is a plan view showing a solder paste application region in Example 19. FIG. 39 is a plan view showing a solder paste application region in Example 20. FIG. 39 is a plan view showing a solder paste application region in Example 21. FIG. 39 is a plan view showing a solder paste application region in Example 22. FIG. 39 is a plan view showing a solder paste application region in Example 23. FIG. 39 is a plan view showing a solder paste application region in Example 24. FIG. 35 is a plan view showing a solder paste application region in Example 25. FIG. 39 is a plan view showing a solder paste application region in Example 26.

Hereinafter, a solder printing apparatus and a method for applying a solder paste according to an embodiment of the present invention will be described with reference to the accompanying drawings.

は ん だ The solder printing apparatus 1 of the present embodiment is a screen printing apparatus using a mask M. As shown in FIG. 1, the solder printing apparatus 1 includes a substrate supporting unit 2 that supports a substrate B on which a solder paste S is to be applied, a printing unit 3 that is disposed vertically above the substrate supporting unit 2, And a housing 4 for accommodating the support unit 2 and the printing unit 3. The mask M is held at a predetermined position in the housing 4 by a mask support (not shown) fixed to the housing 4 and the like.

The substrate supporting unit 2 includes a stage 21 that supports the substrate B from below vertically so that the mounting surface of the substrate B faces vertically upward, and a stage that can move the stage 21 in the horizontal and vertical directions and can rotate around an axis that extends in the vertical direction. And a moving unit 22. The stage 21 is provided with a clamp member 23 for holding the substrate B. Further, the solder printing apparatus 1 is provided with a board transport section (not shown) for loading and unloading the board B between the board support section 2 and the outside of the housing 4.

The printing unit 3 includes a squeegee 31 for moving the solder paste S on the surface (upper surface) of the mask M, a vertical moving device 32 that can move the squeegee 31 up and down, and a horizontal moving device 33 that can move the vertical moving device 32 horizontally. And The squeegee 31 is a member that spreads the solder paste S supplied on the mask M by moving in the horizontal + X direction while being in contact with the surface of the mask M. The squeegee 31 is connected to a vertical moving device 32. The squeegee 31 may be a plate member made of a single material such as metal, resin, or rubber, or a plate member in which a portion of the metal plate or the like that contacts the mask M is covered with resin or rubber. You may. The squeegee 31 is arranged so as to be inclined vertically downward in the −X direction opposite to the + X direction. The inclination angle of the squeegee 31 may be adjustable manually or automatically.

The vertical moving device 32 is supported by the horizontal moving device 33 and includes, for example, a ball screw. The vertical moving device 32 can press the lower end of the squeegee 31 against the surface of the mask M with a predetermined force. The horizontal moving device 33 is fixed to the housing 4, and has a linear guide 34 that guides the vertical moving device 32 in a horizontal direction, and a motor that rotates a ball screw (not shown) provided in parallel with the linear guide 34. 35. The horizontal moving device 33 can move the vertical moving device 32 connected to the ball screw via a nut member in the horizontal direction by driving of the motor 35. The horizontal moving device 33 moves the vertical moving device 32 in the horizontal direction while the squeegee 31 presses the mask M downward by the vertical moving device 32, so that the squeegee 31 presses the mask M. While moving in the horizontal direction. Further, the solder printing apparatus 1 is provided with a dispenser (not shown) for supplying the solder paste S on the mask M.

The housing 4 has sufficient rigidity to support the mask support section and the printing section 3. The housing 4 may have a structure capable of hermetically sealing the inside. When the solder paste S is applied under a reduced-pressure atmosphere, the housing 4 may be provided with an exhaust device such as a vacuum pump and an atmosphere release valve.

2A is a plan view of the substrate B, and FIG. 2B is a plan view of the mask M. In this embodiment, the “plan view” refers to a view as seen from a direction perpendicular to the mounting surface of the substrate B and the upper surface of the mask M.

As shown in FIG. 2A, the substrate B to which the solder paste S is applied in the present embodiment is a printed circuit board made of a hard plate-shaped base material, and has a plurality of pads P (electrodes, bondings) on at least one plate surface. Area). This one plate surface is a mounting surface on which an electronic component E described later is mounted. Examples of the material of the pad P include copper, gold, and silver. A solder resist having a property of repelling molten solder is applied to a region other than the plurality of pads P on the mounting surface of the substrate B.

As shown in FIG. 2B, the mask M used in the present embodiment is made of a metal plate such as stainless steel and has a plurality of openings H penetrating in the thickness direction. The thickness of the mask M is, for example, from 30 μm to 200 μm, but may be changed as appropriate according to the thickness of the solder paste S to be applied on the substrate B. In a conventional screen printing mask, an opening is formed in a region corresponding to a pad of a substrate at a position facing the pad, but the opening H of the present embodiment is formed on a plane different from the pad P of the substrate B. It has a visual shape. That is, in the mask M of the present embodiment, an opening H for applying the solder paste S to an application region at least partially located in the pad P is formed so as to form a non-application region in the pad P of the substrate B. Is formed. In other words, the opening H is formed in the same shape at a position corresponding to the application region. The shape of the opening H in the mask M of the present embodiment, that is, the shape of the application region of the solder paste S applied to the substrate B will be described in detail in Examples 1 to 26 described later. In the mask M shown in FIG. 2B, two rectangular openings H are formed for one pad P, and these openings H are arranged to face each other with the center of the pad P interposed therebetween.

に は The solder paste S used in the present embodiment is not particularly limited, and may be appropriately selected according to the use mode such as the coating atmosphere, the temperature, the opening size and the shape of the mask M. As described above, the solder paste is produced by mixing the solder powder with the flux. Copper, tin, silver, alloys thereof, and the like are used for the solder powder, and the shape of the solder powder may be spherical or irregular. The flux includes, for example, a resin such as rosin, a solvent for adjusting the viscosity and the like, an activator for cleaning the surface of the electrode, and a thixotropic agent for adjusting the viscosity, tackiness and thixotropy. May be appropriately adjusted according to the mode of use.

Next, a method of applying the solder paste S using the solder printing apparatus 1 of the present embodiment will be described with reference to FIG. In FIG. 3, the configuration of the solder printing apparatus 1 other than the squeegee 31 is omitted.

(4) The substrate B is placed on the stage 21 by the substrate transport unit, and the substrate B is held on the stage 21 by the clamp members 23. Subsequently, the horizontal position of the substrate B with respect to the fixed mask M and the rotational position about an axis extending in the vertical direction with respect to the fixed mask M are adjusted by the operation of the stage moving unit 22, and then the stage moving unit 22 is moved from the state shown in FIG. The stage 21 is raised, and the upper surface (mounting surface) of the substrate B is brought into close contact with the lower surface of the mask M as shown in FIG. At this time, since the adjustment of the horizontal position and the rotation position of the substrate B by the stage moving unit 22 has been completed, the opening H of the mask M is arranged at an appropriate position with respect to the pad P of the substrate B. That is, when the surface of the substrate B on which the pads P are provided and the mask M come into contact with each other, a position of the mask M corresponding to (opposed to) the region (application region) where the solder paste S is applied to the substrate B. , An opening H is formed.

(3) Subsequently, as shown in FIG. 3C, the dispenser supplies the solder paste S onto the mask M where the squeegee 31 advances, that is, on the + X side of the squeegee 31. The squeegee 31 is lowered by the driving of the vertical moving device 32, and presses the mask M downward with a predetermined force. In this state, the horizontal moving device 33 moves the vertical moving device 32 in the + X direction, so that the squeegee 31 moves in the + X direction while pressing the mask M. Since the solder paste S is supplied to the position where the squeegee 31 advances, the solder paste S moves in the + X direction as the squeegee 31 moves. Further, since the squeegee 31 is inclined as described above, a force directed vertically downward is applied to the solder paste S as the squeegee 31 moves. For this reason, as shown in FIG. 3D, the solder paste S is pressed into the opening H of the mask M and filled, and comes into contact with the upper surface (mounting surface) of the substrate B. Further, since the squeegee 31 moves in the + X direction while pressing the mask M downward, the squeegee 31 can be moved while scraping the solder paste S from the upper surface of the mask M other than the opening H, so that the solder paste S is supplied only to the opening H. Can be. When the horizontal movement of the squeegee 31 by the horizontal movement device 33 is completed, the filling of the solder paste S into the plurality of openings H of the mask M is completed as shown in FIG.

(3) Subsequently, as shown in FIG. 3F, the stage B is moved down by the stage moving unit 22 so that the substrate B is separated downward from the lower surface of the mask M. At this time, since the solder paste S filled in the opening H adheres to the upper surface of the substrate B, the solder paste S is also separated from the mask M, and thus has a pattern corresponding to the opening H of the mask M. Is printed on the mounting surface of the substrate B. Since the opening H of the mask M has a shape as shown in FIG. 2B, the method of applying the solder paste according to the present embodiment employs a method in which the non-applied region is formed in the pad P on the substrate B. And a step of applying a solder paste S to an application region where at least a part is located. When the substrate B is separated from the lower surface of the mask M and the solder paste S is printed on the substrate B, the solder paste application process of the present embodiment is completed. The board B to which the solder paste S has been applied is carried out of the solder printing apparatus 1 by the board transport unit.

Next, steps after the solder paste application step of the present embodiment in surface mounting will be described with reference to FIG.
First, as shown in FIG. 4A, the electronic component E is mounted on the mounting surface of the substrate B on which the solder paste S has been applied. The electronic component E may be an LGA or a BGA. A plurality of lands L (electrodes) are provided on the bottom surface of the electronic component E (the surface facing the substrate B) so as to correspond to the plurality of pads P of the substrate B. In the step shown in FIG. 4A, the electronic component E is mounted on the substrate B such that the pads P of the substrate B and the lands L of the electronic component E face each other. At this time, the solder paste S is located between the pad P of the substrate B and the land L of the electronic component E.

Subsequently, as shown in FIG. 4B, the substrate B on which the electronic component E is mounted is heated in a reflow furnace (not shown), and the solder powder in the solder paste S is melted and bonded to each other. The molten solder contacts both electrodes of the substrate B and the electronic component E. At this time, due to the action of the flux contained in the solder paste S, the wettability of the molten solder to the pads P is improved, and the surface of the substrate B other than the pads P is coated with a solder resist that repels the molten solder. The molten solder flows radially inward of the pad P. That is, even when the solder paste S is applied to the two regions as in the present embodiment, the solder included in the two regions is integrated in the reflow process. Thereafter, by cooling and solidifying the molten solder, both electrodes of the board B and the electronic component E are electrically connected by the solder S1. Thus, the surface mounting of the electronic component E on the substrate B is completed.

Next, a plurality of specific examples of the method of applying a solder paste according to the present embodiment will be described with reference to the drawings. Further, for comparison with these examples, comparative examples corresponding to the conventional coating method were also examined.
In the following Examples 1 to 26, the application region of the solder paste is described with reference to FIGS. 5 to 30 which are plan views of the mounting surface of the substrate B. This is an enlarged view of one pad P. In each embodiment, the shape of the pad P in plan view was a circle having a diameter of 1.0 mm. In the following description, a direction passing through the center of the pad P and crossing an axis orthogonal to the mounting surface of the substrate B is referred to as a radial direction, and a direction around the axis is referred to as a circumferential direction. Further, for convenience, the vertical direction of the drawing of each drawing may be simply referred to as “vertical direction”, and the horizontal direction of the drawing may be simply referred to as “lateral direction”.
In these examples and comparative examples, a gap ratio GR, a coating area ratio AR, and a maximum void area ratio VR described below were confirmed.

The gap ratio GR refers to a ratio of a gap between a plurality of peripheral regions A1 described later that opens radially outward from the center of the pad P with respect to the entire circumference of the pad P. In other words, when two straight lines extending radially outward from the center of the pad P and not including any of the peripheral regions A1 can be drawn, the ratio of the angle between these two straight lines to 360 ° is defined. The gap ratio GR is set. In the case where a plurality of pairs of two straight lines that do not include the peripheral area A1 can be drawn between them, the ratio of the total angle between the two straight lines of each pair to 360 ° is defined as the gap ratio GR. Note that the calculation of the gap ratio GR does not consider the presence of a central region A2 described later.

The application area ratio AR refers to the ratio of the entire application area of the solder paste applied to one pad P to the area of the pad P. In addition, the circular constant π was set to 3.14.

When confirming the maximum void area ratio VR, two test substrates in which 36 pads P were arranged for each example were prepared, and solder connections were made to electronic components having the same number of lands, respectively. Then, a total of 72 solder connection samples of the pads P were obtained. For this solder connection, the surface mounting method shown in FIGS. 3 and 4 was used. The ratio of the area of the generated voids (area in plan view) to the area of one pad P (hereinafter referred to as void area ratio) is calculated for each of the 72 pads P, and the largest void area ratio among them is calculated. Was defined as the “maximum void area ratio” in each example. The planar shape of the land of the electronic component was equivalent to the pad P.

(Comparative example)
The comparative example has a conventional configuration in which a solder paste is applied to a pad P having a diameter of 1.0 mm in the same region as the pad P. This comparative example is indicated by “Ref” in Table 1 below. In this comparative example, since there is no plurality of peripheral regions, the gap ratio GR cannot be calculated, and the application area ratio AR is 100%. Further, the maximum void area ratio VR was 43.5%.

(Example 1)
The application region of the solder paste in the first embodiment will be described with reference to FIG.
In the first embodiment, the solder paste is applied to the application region T at least partially located in the pad P so as to form the non-application region N in the pad P of the substrate B. In FIG. 5, the region where the solder paste is applied is shaded (the same applies to other FIGS. 6 to 30). The application region T has a plurality (two) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P. Each peripheral area A1 has a rectangular shape extending in one direction, has a length in the longitudinal direction of 0.7 mm, and a width in the transverse direction orthogonal to the longitudinal direction is 0.35 mm.
The plurality of peripheral areas A1 are arranged to face each other with the center O of the pad P interposed therebetween.
The plurality of peripheral areas A1 are arranged so as to extend in a direction orthogonal to the direction in which the plurality of peripheral areas A1 are opposed to each other (vertical direction in FIG. 5). That is, each peripheral area A1 extends in the left-right direction on the paper. Note that a plurality of peripheral regions A1 may be arranged so as to extend in a direction intersecting the opposing direction.
The size of the gap between the plurality of peripheral regions A1 (the gap in the facing direction) is 0.7 mm. Therefore, the gap between the plurality of peripheral regions A1 is 70% of the maximum diameter (1.0 mm) of the pad P, and is 200% of the width of each peripheral region A1 in the facing direction.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
Opposite sides a and b of the plurality of peripheral regions A1 are parallel to each other. The opposite sides a and b may be non-parallel to each other.
The plurality of peripheral areas A1 are arranged so as to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located radially outside the pad P. Note that the configuration may be such that the plurality of peripheral regions A1 are all arranged in the pad P.

When the application region T of this embodiment is divided into four by two straight lines passing through the center O and extending in the vertical and horizontal directions, for example, a straight line L1 extending from the center O to the right side of the paper and extending from the center O to an upper side of the paper Since the section between the straight line L2 and the other three sections is the same or a mirror image, the ratio of the angle θ _{G to} 90 ° between the straight lines L1 and L2 is defined as the gap ratio GR of the present embodiment. The angle θ _G is an angle between the straight line L1 and a straight line L3 extending radially outward from the center O and in contact with the lower right vertex of the peripheral area A1 on the upper side of the drawing. No peripheral area A1 is arranged between the straight lines L1 and L3. Therefore, the gap ratio GR of the present embodiment is (arctan (0.35 / 0.35) / 90 °) = 50%.
The application area ratio AR in this embodiment is (0.7 × 0.35 × 2) / (0.5 ² × π) = 62.4%.
The maximum void area ratio of the present example was 2.3%.

(Example 2)
The application area of the solder paste in the second embodiment will be described with reference to FIG. In the second embodiment, only the configuration different from the first embodiment will be described below, and the description of the other configurations will be omitted.
The size of the gap between the plurality of peripheral areas A1 (the gap in the facing direction) is 0.3 mm. Therefore, the gap between the plurality of peripheral regions A1 is 30% of the maximum diameter (1.0 mm) of the pad P, and is 85.7% of the width of each peripheral region A1 in the facing direction.

The gap ratio GR of the present embodiment is (arctan (0.15 / 0.35) / 90 °) = 25.8%.
The maximum void area ratio of the present example was 13.8%.

(Example 3)
The region where the solder paste is applied in the third embodiment will be described with reference to FIG. In the third embodiment, only the configuration different from the first embodiment will be described below, and the description of the other configurations will be omitted.
The size of the gap (gap in the facing direction) between the plurality of peripheral areas A1 is 0.4 mm. Therefore, the gap between the plurality of peripheral regions A1 is 40% of the maximum diameter (1.0 mm) of the pad P, and is 114% of the width of each peripheral region A1 in the facing direction.

The gap ratio GR of the present embodiment is (arctan (0.2 / 0.35) / 90 °) = 33%.
The maximum void area ratio of the present example was 11.7%.

(Example 4)
The solder paste application area in the fourth embodiment will be described with reference to FIG. In the fourth embodiment, only configurations different from those of the first embodiment will be described below, and descriptions of other configurations will be omitted.
The size of the gap between the plurality of peripheral areas A1 (the gap in the facing direction) is 0.5 mm. Therefore, the gap between the plurality of peripheral regions A1 is 50% of the maximum diameter (1.0 mm) of the pad P, and is 143% of the width of each peripheral region A1 in the facing direction.

The gap ratio GR of the present embodiment is (arctan (0.25 / 0.35) / 90 °) = 39.5%.
The maximum void area ratio of the present example was 7.0%.

(Example 5)
The application region of the solder paste in the fifth embodiment will be described with reference to FIG. In the fifth embodiment, only the configuration different from the first embodiment will be described below, and the description of the other configurations will be omitted.
The size of the gap between the plurality of peripheral areas A1 (the gap in the facing direction) is 0.6 mm. Therefore, the gap between the plurality of peripheral regions A1 is 60% of the maximum diameter (1.0 mm) of the pad P, and is 171% of the width of each peripheral region A1 in the facing direction.

The gap ratio GR in this embodiment is (arctan (0.3 / 0.35) / 90 °) = 45.1%.
The maximum void area ratio in the present example was 4.2%.

(Study of Examples 1 to 5)
The maximum void area ratios VR of Examples 1 to 5 were all lower than those of Comparative Examples. Therefore, it can be seen that the size of the generated voids could be suppressed in any of Examples 1 to 5.
The reason why the size of the void could be suppressed will be discussed below. When the solder powders melted in the reflow step are bonded to each other, the resin component of the flux located between the solder powders before the melting is extruded outward by the bonding of the molten solder. However, if the solder paste application area is large, the solder cools and solidifies before the resin component is discharged from the solder, so that the resin component was left in the solder (ie, voids). Can be On the other hand, in Examples 1 to 5, the width of each peripheral area A1 is 0.35 mm, which is significantly smaller than the maximum diameter (1.0 mm) of the pad P. For this reason, when the resin component or the like of the flux moves in the short direction of the peripheral area A1, the flux is discharged from the molten solder relatively early, and the size of the void is suppressed in each peripheral area A1 as compared with the comparative example. It is thought that.
Further, as shown in FIG. 4, the solder powder in the solder paste applied to the two regions is also integrated in the reflow process. That is, the solder powder melted in the two peripheral regions A1 flows toward the center O of the pad P and comes into contact with each other near the center of the pad P. Since the flow of the molten solder flowing inward in the radial direction is maintained, the connection portion of the molten solder flowing from the two regions expands outward in the radial direction. It is considered that since the connecting portion expands outward in the radial direction, a force for causing the resin component of the flux to move outward in the radial direction is generated, and it is considered that the resin component can be discharged toward the outside of the solder by this force.

In Examples 1 to 5, the gap between the plurality of peripheral regions A1 was 30% or more and 70% or less of the maximum diameter (1.0 mm) of the pad P.
The gap between the plurality of peripheral regions A1 was 85.7% or more and 200% or less of the width of each peripheral region A1 in the facing direction of the plurality of peripheral regions A1.

(Modifications of Embodiments 1 to 5)
The following modifications are conceivable in the first to fifth embodiments.
Each peripheral area A1 has a rectangular shape in plan view, but may have an elliptical or elliptical shape in plan view. Although the opposing sides a and b of the plurality of peripheral areas A1 are formed in a straight line, the opposing sides may have a shape that bulges inward in the radial direction, or may bulge outward in the radial direction. It may have a concave shape. Similarly, the radially outer side of the peripheral region A1 may be depressed inward in the radial direction or may bulge outward in the radial direction.

(Example 6)
The solder paste application area in the sixth embodiment will be described with reference to FIG.
In the sixth embodiment, the solder paste is applied to the application region T at least partially located in the pad P so as to form the non-application region N in the pad P of the substrate B. The application region T includes a plurality (six) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the plurality of peripheral regions A1. And Each of the peripheral area A1 and the central area A2 has a square shape with a side length of 0.3 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral areas A1 are arranged at substantially equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
Opposite sides a and b of a plurality of peripheral regions A1 circumferentially adjacent to each other are parallel to each other. The opposite sides a and b may be non-parallel to each other.
Opposite sides c and d of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides c and d may be non-parallel to each other.
The area of the central area A2 is the same (100%) as the area of each peripheral area A1.
The plurality of peripheral areas A1 are arranged so as to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located radially outside the pad P. Note that the configuration may be such that the plurality of peripheral regions A1 are all arranged in the pad P.

When the application region T of this embodiment is divided into four by two straight lines passing through the center O and extending in the vertical and horizontal directions, for example, a straight line L1 extending from the center O to the right side of the paper and extending from the center O to an upper side of the paper Since the section between the straight line L2 and the other three sections is the same or a mirror image, the ratio of the sum of the angle θ _G1 and the angle θ _G2 to 90 ° formed between the straight lines L1 and L2 is determined by the gap in the present embodiment. The ratio GR was set. The angle θ _G1 is an angle between the straight line L1 and a straight line L3 extending radially outward from the center O and in contact with the lower right vertex of the peripheral area A1 on the upper right of the paper, and arctan (0.1 / 0) .65). The angle θ _G2 is a straight line L4 extending radially outward from the center O and in contact with the upper left vertex of the peripheral area A1 on the upper right of the drawing, and a straight line L4 extending radially outward from the center O and a lower right apex of the upper peripheral area A1 on the drawing. And an angle between the straight line L5 and the arc L, which is expressed by (arctan (0.35 / 0.15) -arctan (0.4 / 0.35)). Therefore, the gap ratio GR of the present embodiment is (θ _G1 + θ _G2 ) /90°=29.7%.
The application area ratio AR in this embodiment is (0.3 ² × 7) / (0.5 ² × π) = 80.3%.
The maximum void area ratio of the present example was 4.8%.

(Example 7)
The application area of the solder paste in the seventh embodiment will be described with reference to FIG. In the seventh embodiment, only the configuration different from the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The central area A2 has a square shape with a side length of 0.4 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
Area of the central region A2 is ^178% of the area of each peripheral regions ^{A1 (= 0.4 2 /0.3 2)} .

The gap ratio GR of the present embodiment is 29.7%, similarly to the sixth embodiment.
The application area ratio AR in this embodiment is (0.3 ² × 6 + 0.4 ² ) / (0.5 ² × π) = 89.2%.
The maximum void area ratio of the present example was 3.9%.

(Example 8)
The solder paste application area in the eighth embodiment will be described with reference to FIG. In the eighth embodiment, only the configuration different from the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The central region A2 has a square shape with a side length of 0.5 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The area of the central area A2 is 278% (= 0.5 ² /0.3 ² ) of the area of each peripheral area A1.

The gap ratio GR of the present embodiment is 29.7%, similarly to the sixth embodiment.
The application area ratio AR in this embodiment is (0.3 ² × 6 + 0.5 ² ) / (0.5 ² × π) = 100.6%.
The maximum void area ratio of the present example was 13.9%.

(Example 9)
The application area of the solder paste in the ninth embodiment will be described with reference to FIG. In the ninth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The central area A2 has a square shape with a side length of 0.2 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The area of the central area A2 is 44.4% (= 0.2 ² /0.3 ² ) of the area of each peripheral area A1.

The gap ratio GR of the present embodiment is 29.7%, similarly to the sixth embodiment.
The application area ratio AR in this embodiment is (0.3 ² × 6 + 0.2 ² ) / (0.5 ² × π) = 73.9%.
The maximum void area ratio of the present example was 12.3%.

(Example 10)
The application area of the solder paste in the tenth embodiment will be described with reference to FIG. In the tenth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application area T includes a plurality (two) of peripheral areas A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central area A2 located radially inside the plurality of peripheral areas A1. And Each of the peripheral area A1 and the central area A2 has a square shape with a side length of 0.3 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
Opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides a and b may be non-parallel to each other.

When the application region T of this embodiment is divided into four by two straight lines passing through the center O and extending in the vertical and horizontal directions, for example, a straight line L1 extending from the center O to the right side of the paper and extending from the center O to an upper side of the paper Since the section between the straight line L2 and the other three sections is the same or a mirror image, the ratio of the angle θ _{G to} 90 ° between the straight lines L1 and L2 is defined as the gap ratio GR of the present embodiment. The angle θ _G is an angle between the straight line L1 and a straight line L3 extending radially outward from the center O and in contact with the lower right vertex of the peripheral region A1 on the upper side of the drawing. No peripheral area A1 is arranged between the straight lines L1 and L3. Therefore, the gap ratio GR of the present embodiment is (arctan (0.35 / 0.15) / 90 °) = 74.2%.
The application area ratio AR in this example is (0.3 ² × 3) / (0.5 ² × π) = 34.4%.
The maximum void area ratio of the present example was 3.1%.

(Example 11)
The application region of the solder paste in the eleventh embodiment will be described with reference to FIG. In the eleventh embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (three) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the peripheral regions A1. And The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral areas A1 are arranged at substantially equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
Opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides a and b may be non-parallel to each other.

When the application region T of the present embodiment is divided into two by a straight line extending through the center O and extending in the up-down direction, the right-hand section of the straight line is a mirror image of the left-hand section, and therefore, the straight line L1 extending upward from the center O. The ratio of the sum of the angles θ _G1 , θ _G2, and θ _{G3 to} 180 ° formed between the straight line L2 extending downward from the center O is defined as the gap ratio GR of the present embodiment. The angle θ _G1 is an angle between a straight line L3 extending from the center O to the right side of the drawing and a straight line L4 extending radially outward from the center O and in contact with the lower right vertex of the peripheral region A1 on the upper side of the drawing. , Arctan (0.35 / 0.15). The angle θ _G2 is an angle between the straight line L2 and a straight line L5 extending radially outward from the center O and in contact with the lower left vertex of the peripheral area A1 on the lower right side of the drawing, and is (90 ° −arctan (0 .45 / 0.35)). The angle θ _G3 is an angle between the straight line L3 and a straight line L6 extending radially outward from the center O and in contact with the upper right vertex of the peripheral area A1 on the lower right of the paper, and arctan (0.15 / 0) .65)). Therefore, the gap ratio GR of the present embodiment is (θ _G1 + θ _G2 + θ _G3 ) /90°=65.4%.
The application area ratio AR in this example is (0.3 ² × 4) / (0.5 ² × π) = 45.9%.
The maximum void area ratio of the present example was 4.0%.

(Example 12)
The application area of the solder paste in the twelfth embodiment will be described with reference to FIG. In the twelfth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (four) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the peripheral regions A1. And Each of the peripheral area A1 and the central area A2 has a square shape with a side length of 0.3 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
Opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides a and b may be non-parallel to each other.

When the application region T of this embodiment is divided into four by two straight lines passing through the center O and extending in the vertical and horizontal directions, for example, a straight line L1 extending from the center O to the right side of the paper and extending from the center O to an upper side of the paper Since the section between the straight line L2 and the other three sections is the same or a mirror image, the ratio of the angle θ _{G to} 90 ° between the straight lines L1 and L2 is defined as the gap ratio GR of the present embodiment. The angle θ _G is a straight line L3 extending radially outward from the center O and in contact with the upper left vertex of the peripheral region A1 on the right side of the drawing, and a straight line L3 extending radially outward from the center O and a lower right vertex of the peripheral region A1 on the upper side of the drawing. And the straight line L4 that is in contact with No peripheral area A1 is arranged between the straight lines L3 and L4. Therefore, the gap ratio GR in the present embodiment is (arctan (0.35 / 0.15) -arctan (0.15 / 0.35)) = 48.4%.
The application area ratio AR in this embodiment is (0.3 ² × 5) / (0.5 ² × π) = 57.1%.
The maximum void area ratio in the present example was 2.6%.

(Example 13)
The solder paste application area in the thirteenth embodiment will be described with reference to FIG. In the thirteenth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (four) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the peripheral regions A1. And The plurality of peripheral regions A1 have a first region A11 and a second region A12 having different circumferential lengths, and the first region A11 and the second region A12 are alternately arranged in the circumferential direction. The first area A11 and the second area A12 are provided two by two. The first region A11 has a rectangular shape extending in one direction, has a length in the longitudinal direction of 0.6 mm, and has a width in the short direction orthogonal to the longitudinal direction of 0.3 mm. Each of the second area A12 and the central area A2 is a square having a side length of 0.3 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of first regions A11, the plurality of second regions A12, and the central region A2 is shown in FIG.
Opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides a and b may be non-parallel to each other.

The gap ratio GR of the present embodiment is calculated in the same manner as in the twelfth embodiment, and is (arctan (0.35 / 0.15) -arctan (0.3 / 0.35)) = 29.1%.
The application area ratio AR in this embodiment is (0.6 × 0.3 × 2 + 0.3 ² × 3) / (0.5 ² × π) = 34.6%.
The maximum void area ratio in this example was 1.8%.

(Example 14)
The area where the solder paste is applied in Example 14 will be described with reference to FIG. In the fourteenth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (six) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the plurality of peripheral regions A1. And Each of the peripheral area A1 and the central area A2 has a square shape with a side length of 0.3 mm. However, in the peripheral area A1, a portion radially outside the outer edge of the pad P is excluded. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
Opposite sides a and b of a plurality of peripheral regions A1 circumferentially adjacent to each other are parallel to each other. The opposite sides a and b may be non-parallel to each other.
Opposite sides c and d of the central area A2 and the peripheral areas A1 are parallel to each other. The opposite sides c and d may be non-parallel to each other.

The gap ratio GR of the present embodiment was calculated by the same method as in the sixth embodiment. However, since the angle θ _G1 is represented by arcsin (0.05 / 0.5), the gap ratio GR is (θ a _G1 + _{θ G2) /90°=11.5%.}
The application area ratio AR of this embodiment is about 43%.
The maximum void area ratio of the present example was 13.8%.

(Study of Examples 6 to 14)
The maximum void area ratios VR of Examples 6 to 14 were all lower than those of Comparative Examples. Therefore, it can be seen that the size of the generated voids could be suppressed in any of Examples 6 to 14.
The reason why the size of the void could be suppressed will be discussed below. First, since the peripheral region A1 and the central region A2 are smaller than the application region of the comparative example, it is considered that the resin component of the flux is easily discharged from the molten solder early as in the first to fifth embodiments. .
Further, although all of Examples 6 to 14 have the central region A2, the solder powder in the solder paste applied to the central region A2 flows radially outward after melting. Note that the ratio of the gap between the plurality of peripheral regions A1 opening radially outward from the center O of the pad P to the entire circumference of the pad P is calculated as the gap ratio GR. It was also found that in the embodiment of the present invention, the opening was provided from the center O toward the outside in the radial direction with an interval G therebetween. For this reason, it is considered that the molten solder from the central region A2 can appropriately flow radially outward through the gap G, and thereby the resin component of the flux can be discharged radially outward.
In Examples 6 to 14, the area of the central region A2 was 44.4% or more and 278% or less of the area of each peripheral region A1.

(Example 15)
The application region of the solder paste in the embodiment 15 will be described with reference to FIG. In the fifteenth embodiment, only the configuration different from that of the twelfth embodiment will be described below, and the description of the other configurations will be omitted.
The fifteenth embodiment has a configuration in which the central region A2 is excluded from the twelfth embodiment.
The gap ratio GR of the present embodiment is the same as that of the twelfth embodiment, and is 48.4%.
The application area ratio AR of this embodiment is (0.3 ² × 4) / (0.5 ² × π) = 45.7%.
The maximum void area ratio of the present example was 13.4%.

(Example 16)
The application region of the solder paste in the sixteenth embodiment will be described with reference to FIG. In the sixteenth embodiment, only the configuration different from that of the thirteenth embodiment will be described below, and the description of the other configurations will be omitted.
The sixteenth embodiment has a configuration in which the central region A2 is excluded from the thirteenth embodiment.
The gap ratio GR of the present embodiment is the same as that of the thirteenth embodiment, and is 29.1%.
The coating area ratio AR in this embodiment is (0.6 × 0.3 × 2 + 0.3 ² × 2) / (0.5 ² × π) = 23.2%.
The maximum void area ratio of the present example was 13.8%.

(Study of Examples 15 and 16)
The maximum void area ratios VR of Examples 15 and 16 were all lower than those of Comparative Examples. Therefore, it can be seen that in each of Examples 15 and 16, the size of the generated void could be suppressed.
When the cause of the suppression of the size of the void is examined below, since the peripheral region A1 and the central region A2 are smaller than the application region of the comparative example, the resin component of the flux is easily discharged from the molten solder at an early stage. It is considered to be the same as in Examples 1 to 5.

(Example 17)
The application area of the solder paste in the seventeenth embodiment will be described with reference to FIG. In the seventeenth embodiment, only the configuration different from that of the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (six) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the plurality of peripheral regions A1. And Each of the peripheral area A1 and the central area A2 has a circular shape with a diameter of 0.3 mm. The center of each peripheral area A1 is located on the outer peripheral edge of the pad P. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
The area of the central area A2 is the same (100%) as the area of each peripheral area A1.
The plurality of peripheral areas A1 are arranged so as to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located radially outside the pad P. Note that the configuration may be such that the plurality of peripheral regions A1 are all arranged in the pad P.

The gap ratio GR according to the present embodiment is calculated. The angle θ _C is defined by a straight line L1 extending radially outward from the center O and passing through the center of the peripheral area A1 on the upper right of the drawing, and a straight line L2 extending radially outward from the center O and contacting the peripheral area A1 on the upper right of the drawing. The angle between, expressed as arcsin (0.15 / 0.5). The peripheral area A1 is located between the straight lines L1 and L2. Therefore, the gap ratio GR of the present embodiment is (180 ° −6 × θ _C ) /180°=41.8%.
The application area ratio AR in this embodiment is (0.15 ² × π × 7) / (0.5 ² × π) = 63%.
The maximum void area ratio of the present example was 10.9%.

(Example 18)
The area to which the solder paste is applied in Example 18 will be described with reference to FIG. In the eighteenth embodiment, only the configuration different from that of the seventeenth embodiment will be described below, and the description of the other configurations will be omitted.
The central area A2 has a circular shape with a diameter of 0.4 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The area of the central area A2 is 178% of the area of each peripheral area A1.
The gap ratio GR of the present embodiment is 41.8% as in the seventeenth embodiment.
The application area ratio AR in this embodiment is (0.15 ² × π × 6 + 0.2 ² × π) / (0.5 ² × π) = 43.1%.
The maximum void area ratio of the present example was 4.6%.

(Example 19)
The application area of the solder paste in the nineteenth embodiment will be described with reference to FIG. In the nineteenth embodiment, only the configuration different from that of the seventeenth embodiment will be described below, and description of the other configurations will be omitted.
The central area A2 has a circular shape with a diameter of 0.5 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The area of the central area A2 is 278% of the area of each peripheral area A1.
The gap ratio GR of the present embodiment is 41.8% as in the seventeenth embodiment.
The application area ratio AR in this embodiment is (0.15 ² × π × 6 + 0.25 ² × π) / (0.5 ² × π) = 48.7%.
The maximum void area ratio in the present example was 12.4%.

(Example 20)
The solder paste application area in the twentieth embodiment will be described with reference to FIG. In the twentieth embodiment, only the configuration different from that of the seventeenth embodiment will be described below, and the description of the other configurations will be omitted.
The central region A2 has a circular shape with a diameter of 0.2 mm. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. FIG. 24 shows the mutual positional relationship between the plurality of peripheral areas A1 and the central area A2.
The area of the central area A2 is 44.4% of the area of each peripheral area A1.
The gap ratio GR of the present embodiment is 41.8% as in the seventeenth embodiment.
The coating area ratio AR in this embodiment is (0.15 ² × π × 6 + 0.1 ² × π) / (0.5 ² × π) = 35.7%.
The maximum void area ratio of the present example was 17.8%.

(Example 21)
The application region of the solder paste in the twenty-first embodiment will be described with reference to FIG. In the twenty-first embodiment, only the configuration different from the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application area T includes a plurality (two) of peripheral areas A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central area A2 located radially inside the plurality of peripheral areas A1. And Each of the peripheral area A1 and the central area A2 has a circular shape with a diameter of 0.3 mm. The center of each peripheral area A1 is located on the outer peripheral edge of the pad P. The central area A2 is arranged such that the center thereof coincides with the center O of the pad P in plan view. The positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
The gap ratio GR of this embodiment is (180 ° −2 × θ _C ) /180°=80.6% with reference to the seventeenth embodiment.
The application area ratio AR in this embodiment is (0.15 ² × π × 3) / (0.5 ² × π) = 27%.
The maximum void area ratio of the present example was 3.8%.

(Example 22)
The area to which the solder paste is applied in Example 22 will be described with reference to FIG. In the twenty-second embodiment, only the configuration different from the sixth embodiment will be described below, and the description of the other configurations will be omitted.
The application region T includes a plurality (four) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central region A2 located radially inward of the peripheral regions A1. And Each of the peripheral area A1 and the central area A2 has a circular shape with a diameter of 0.3 mm. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
The gap ratio GR of the present embodiment is (180 ° −4 × θ _C ) /180°=61.2% with reference to the seventeenth embodiment.
The application area ratio AR of this embodiment is (0.15 ² × π × 5) / (0.5 ² × π) = 45%.
The maximum void area ratio in this example was 4.9%.

(Study of Examples 17 to 22)
The maximum void area ratios VR of Examples 17 to 22 were all lower than those of Comparative Examples. For this reason, it can be seen that in all of Examples 17 to 22, the size of the generated void could be suppressed.
The reason why the size of the void could be suppressed will be discussed below. First, since the peripheral region A1 and the central region A2 are smaller than the application region of the comparative example, it is considered that the resin component of the flux is easily discharged from the molten solder early as in the first to fifth embodiments. .
In addition, although Examples 17 to 22 all have the central region A2, the solder powder in the solder paste applied to the central region A2 flows radially outward after melting. The ratio of the gap between the plurality of peripheral regions A1 opening radially outward from the center O of the pad P with respect to the entire circumference of the pad P is calculated as the gap ratio GR. It was also found that in the embodiment of the present invention, the opening was provided from the center O toward the outside in the radial direction with an interval G therebetween. For this reason, it is considered that the molten solder from the central region A2 can appropriately flow radially outward through the gap G, and thereby the resin component of the flux can be discharged radially outward.
In Examples 17 to 22, the area of the central area A2 was 44.4% or more and 278% or less of the area of each peripheral area A1.

(Example 23)
The area to which the solder paste is applied in Example 23 will be described with reference to FIG.
In the embodiment 23, the solder paste is applied to the application region T where at least a part is located in the pad P so that the non-application region N is formed in the pad P of the substrate B. The application region T has a plurality (two) of peripheral regions A1 arranged at intervals G in the circumferential direction around the center O of the pad P. The two peripheral regions A1 are arranged so as to be in contact with each other at a part on the radially inner side. In the present embodiment, the contact points of the two peripheral areas A1 are arranged at the same position as the center O in plan view. The shape of each peripheral area A1 is a right-angled isosceles triangle having a vertex located at the center O and an apex angle of 90 °. The length of the bottom side (side facing the apex) of each peripheral area A1 is 1.0 mm. The distance between the bottom sides of the two peripheral areas A1 is also 1.0 mm. The circumferential width of each peripheral area A1 gradually increases from the center O of the pad P toward the outside in the radial direction.
The plurality of peripheral regions A1 are arranged at equal intervals in the circumferential direction. Note that the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.
The plurality of peripheral areas A1 are arranged so as to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located radially outside the pad P. Note that the configuration may be such that the plurality of peripheral regions A1 are all arranged in the pad P.
The gap ratio GR of the present embodiment is 50%.
The application area ratio AR in this embodiment is (1.0 ² /2)/(0.5 ² × π) = 63.7%.
The maximum void area ratio of the present example was 12.5%.

(Example 24)
The application area of the solder paste in Example 24 will be described with reference to FIG. In the twenty-fourth embodiment, only the configuration different from that of the twenty-third embodiment will be described below, and the description of the other configurations will be omitted.
The length of the base of each peripheral area A1 is 1.3 mm. The distance between the bases of the two peripheral regions A1 is also 1.3 mm.
The application area ratio AR in this embodiment is (1.3 ² /2)/(0.5 ² × π) = 107.6%.
The maximum void area ratio in this example was 14.6%.

(Study of Examples 23 and 24)
The maximum void area ratios VR of Examples 23 and 24 were all lower than those of Comparative Examples. Therefore, it can be seen that in each of Examples 23 and 24, the size of the generated void could be suppressed.
The reason why the size of the void could be suppressed will be discussed below. First, since the peripheral region A1 is smaller than the application region of the comparative example, it is considered that the resin component of the flux is easily discharged from the molten solder at an early stage, as in the case of Examples 1 to 5.
Although Examples 23 and 24 do not have a central area, the radially inner part of the peripheral area A1 reaches the central part of the pad P. For this reason, the solder powder in the solder paste applied to the radially inner portion of the peripheral region A1 may flow in the lateral direction on the paper toward the radially outer side after melting. In addition, by calculating the gap ratio GR, it was found that in each of the embodiments 23 and 24, the opening was provided from the center O toward the outside in the radial direction with a gap G therebetween. For this reason, the molten solder from the radially inner portion of the peripheral region A1 can appropriately flow radially outward through the gap G, whereby the resin component and the like of the flux can be discharged radially outward. it is conceivable that.

(Modifications of Embodiments 23 and 24)
The following modifications are conceivable for the embodiments 23 and 24.
In these embodiments, two peripheral areas A1 are provided, but the number of peripheral areas A1 may be three or more. In this case, the rate of expansion in the circumferential direction of each peripheral region A1 toward the outside in the radial direction may be reduced. Further, the contact point between the two peripheral regions A1 may be arranged at a position different from the center O of the pad P in plan view.

(Example 25)
The application area of the solder paste in the twenty-fifth embodiment will be described with reference to FIG.
In the twenty-fifth embodiment, the solder paste is applied to the application region T at least partially located in the pad P so as to form the non-application region N in the pad P of the substrate B. The application region T includes an extension region A3 that includes the center O of the pad P and extends in one direction (in the present embodiment, the left-right direction in the drawing). The planar shape of the extension region A3 is rectangular, the length in the longitudinal direction is 1.3 mm, and the width in the lateral direction is 0.3 mm.
The extension region A3 is arranged so as to overlap the outer edge of the pad P. That is, a part of the extension region A3 is located radially outside the pad P. In the present embodiment, both longitudinal ends of the extension region A3 are located radially outside the pad P. Note that the configuration may be such that the entire extension region A3 is arranged in the pad P, or only one end in the longitudinal direction of the extension region A3 may be located radially outside the pad P.
In the present embodiment, the gap ratio GR cannot be calculated because the extension region A3 reaches the outside of the pad P in the radial direction.
The application area ratio AR in this embodiment is (1.3 × 0.3) / (0.5 ² × π) = 49.7%.
The maximum void area ratio of the present example was 17.5%.

(Example 26)
The solder paste application region in the twenty-sixth embodiment will be described with reference to FIG. In the twenty-sixth embodiment, only the configuration different from that of the twenty-fifth embodiment is described below, and the description of the other configurations is omitted.
The application region T further includes a plurality (two) of side regions A4 arranged so as to sandwich the extension region A3 in a direction intersecting the longitudinal direction of the extension region A3. The planar shape of each side area A4 is a square having a side of 0.3 mm in length, and one side of the side area A4 extends in the vertical direction on the paper. The mutual positional relationship between the plurality of side regions A4 and the extended region A3 is shown in FIG.
Opposite sides a and b of the extension region A3 and the side regions A4 are parallel to each other. The opposite sides a and b may be non-parallel to each other.
The plurality of side areas A4 are arranged so as to overlap the outer edge of the pad P. That is, a part of each side area A4 is located radially outside the pad P. Note that the configuration may be such that the plurality of side regions A4 are all arranged in the pad P.
The application area ratio AR of this embodiment is (1.3 × 0.3 + 0.3 ² × 2) / (0.5 ² × π) = 72.6%.
The maximum void area ratio in the present example was 15.0%.

(Study of Examples 25 and 26)
The maximum void area ratios VR of Examples 25 and 26 were all lower than those of Comparative Examples. Therefore, it can be seen that in each of Examples 25 and 26, the size of the generated void could be suppressed.
When the cause of the suppression of the size of the voids is examined below, since the extending region A3 and the side region A4 are smaller than the application region of the comparative example, the resin component of the flux is easily discharged from the molten solder at an early stage. This is considered to be the same as in Examples 1 to 5.

(Modifications of Embodiments 25 and 26)
The following modifications can be considered for the embodiments 25 and 26.
For example, the number of the plurality of side regions A4 may be three or more.

Table 1 shows the gap ratio GR, the coating area ratio AR, and the maximum void area ratio VR of Examples 1 to 26 described above.

最大 The maximum void area ratios VR of Examples 1 to 26 were all lower than those of Comparative Examples. Therefore, it can be seen that the size of the generated voids could be suppressed in all of the examples. Therefore, it is possible to secure an appropriate electrical connection between the object to be coated such as a substrate and the two electrodes of the electronic component, and to prevent a decrease in strength of a solder connecting between the two electrodes. Can be provided.

Although an embodiment of the present invention has been described above, the present invention is not limited to the embodiment. Additions, omissions, substitutions, and other modifications of the configuration can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the shape of the pad P on the substrate B, which is the object to be coated, is circular in plan view, but is not limited thereto, and may be, for example, rectangular or polygonal.

In the above embodiment, a printed board made of a hard plate-shaped base material is used as an object to be applied, but a flexible substrate may be used as an object to be applied with a solder paste. When one electronic component is directly connected to another electronic component, a solder paste may be applied to the electrode surface of the one electronic component as an application target. The object to be applied may be any member as long as the solder paste can be applied.

In the above embodiment, when the solder paste is applied to the object to be applied, screen printing using the mask M is used. However, the dispenser having the discharge nozzle movable on the substrate is used, and A method of directly applying the solder paste to the application region as shown in FIG. 26 without using a mask or the like may be used.

Further, the present invention may include the following aspects.
A fourth aspect of the present invention is a mask for applying a solder paste to an application object, at least a part of which is formed in the bonding region so as to form a non-application region in the bonding region of the application object. An opening is formed at a position corresponding to the located application region, and the opening has a plurality of peripheral openings arranged at intervals in a circumferential direction around a center of the joining region.
According to a fifth aspect of the present invention, there is provided a mask for applying a solder paste to an object to be applied, wherein at least a part of the mask is formed in the joining region so as to form a non-application region in the joining region of the object. An opening is formed at a position corresponding to the located application region, and the opening has an extension opening including the center of the joining region and extending in one direction.

INDUSTRIAL APPLICABILITY The present invention is applicable to a method of applying a solder paste to an object to be applied such as a printed circuit board, and a mask used for the application. Even when voids are formed in solder in surface mounting, the voids may be formed. Can be suppressed.

A1 Peripheral area A11 First area A12 Second area A2 Central area A3 Extended area A4 Side area B Substrate (object to be coated)
N Non-coating area O Center P Pad (joining area)
S Solder paste T Application area

Claims (25)

1. A method of applying a solder paste to an object to be applied,
   A step of applying a solder paste to an application region at least partially located in the bonding region so as to form a non-application region in a bonding region of the application target,
   The method of applying a solder paste, wherein the application region has a plurality of peripheral regions arranged at intervals in a circumferential direction around a center of the bonding region.
2. The solder paste application method according to claim 1, wherein the plurality of peripheral regions are arranged to face each other with the center of the bonding region interposed therebetween.
3. The method according to claim 2, wherein the plurality of peripheral regions are arranged so as to extend in a direction intersecting a direction in which the plurality of peripheral regions oppose each other.
4. 4. The solder paste application method according to claim 2, wherein a gap between the plurality of peripheral regions is 30% or more and 70% or less of a maximum diameter of the joining region. 5.
5. 5. The solder according to claim 2, wherein a gap between the plurality of peripheral regions is equal to or greater than 85.7% and equal to or less than 200% of a width of each peripheral region in a direction facing the plurality of peripheral regions. Paste application method.
6. The method according to claim 1, wherein the number of the plurality of peripheral regions is two to six.
7. 7. The method according to claim 1, wherein the plurality of peripheral regions are arranged at equal intervals in the circumferential direction. 8.
8. The plurality of peripheral regions include a first region and a second region having different circumferential lengths,
   The method of claim 1, wherein the first region and the second region are alternately arranged in the circumferential direction.
9. The solder paste application method according to any one of claims 1 to 8, wherein opposing sides of the plurality of peripheral regions adjacent in the circumferential direction are parallel to each other.
10. 10. The method of applying a solder paste according to claim 1, wherein the application region further has a central region located radially inward of the plurality of peripheral regions. 11.
11. The solder paste application method according to claim 10, wherein opposing sides of the central region and each peripheral region are parallel to each other.
12. The solder paste application method according to claim 10 or 11, wherein the area of the central region is not less than 44.4% and not more than 278% of the area of each peripheral region.
13. The method according to claim 1, wherein the plurality of peripheral regions are partially arranged in contact with each other.
14. 14. The method of applying a solder paste according to claim 13, wherein the circumferential width of each peripheral region gradually increases from the center of the joining region toward the outside in the radial direction.
15. The ratio of a gap between the plurality of peripheral regions, which opens radially outward from the center of the bonding region, to the entire periphery of the bonding region is 11.5% or more. A method for applying the solder paste according to any one of the preceding claims.
16. The method according to any one of claims 1 to 15, wherein the plurality of peripheral regions are arranged so as to overlap an outer edge of the bonding region.
17. The method according to any one of claims 1 to 15, wherein the plurality of peripheral regions are arranged in the bonding region.
18. A method of applying a solder paste to an object to be applied,
    A step of applying a solder paste to an application region at least partially located in the bonding region so as to form a non-application region in a bonding region of the application target,
    The solder paste application method, wherein the application area includes an extension area including the center of the bonding area and extending in one direction.
19. 19. The method for applying a solder paste according to claim 18, wherein the extension region is disposed so as to overlap an outer edge of the joining region.
20. 19. The method for applying a solder paste according to claim 18, wherein the extension region is disposed in the bonding region.
21. The solder according to any one of claims 18 to 20, wherein the application region further has a plurality of side regions arranged so as to sandwich the extension region in a direction intersecting the longitudinal direction of the extension region. How to apply the paste.
22. 22. The method for applying a solder paste according to claim 21, wherein opposing sides of the extension region and the side regions are parallel to each other.
23. 23. The method for applying a solder paste according to claim 21, wherein the plurality of side regions are arranged so as to overlap an outer edge of the bonding region.
24. 23. The method of applying a solder paste according to claim 21, wherein the plurality of side regions are arranged in the bonding region.
25. A mask used in the method for applying a solder paste according to any one of claims 1 to 24,
    A mask having an opening formed at a position corresponding to the application region.

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