TW202034752A - Application method of solder paste and mask - Google Patents

Abstract

The application method of solder paste to an application object (B), includes a step of applying solder paste to an application area (T), in which at least part of the application area (T) is positioned in a boding area (P) of the application object (B), such that a non-application area (N) is formed in the bonding area (P), wherein the application area (T) includes a plurality of peripheral areas (A1) disposed at intervals in a circumferential direction around the center (O) of the bonding area (P).

Description

Soldering paste coating method and mask

The present invention relates to a coating method and mask of solder paste.

This case claims priority based on Japanese Patent Application No. 2018-166395 filed in Japan on September 5, 2018, and the content of the Japanese application is used here.

In the past, in the surface mount technology (SMT: Surface Mount Technology) that mounts electronic components such as LGA (Land Grid Array) and BGA (Ball Grid Array) on the surface of a printed circuit board, the solder paste (solder paste) It is widely used. The solder paste is made by mixing solder powder with flux. Surface mounting technology is to first apply solder paste on the surface of the printed circuit board with pads (electrodes). At this time, the solder paste is applied to the aforementioned solder pad, and its application range is the same as the size of the solder pad. Then, the pads of the printed circuit board are opposed to the land (electrode) of the electronic component, and the electronic component is placed on the surface of the printed circuit board. At this time, the solder paste is located between the printed circuit board and the electrodes on both sides of the electronic component. Finally, use a reflow oven (retlow oven) to heat (reflow) the printed circuit board on which the electronic components are placed, so that the solder powder of the solder paste is melted and combined. After cooling and solidification, the two electrodes are electrically connected to This surface installation is complete. In order to ensure proper electrical connection, the resistance of the solder connecting the two electrodes must be below a predetermined value. In addition, even if the printed circuit board after surface mounting is In the case of shocks, etc., proper electrical connections are maintained without damage, and there is a requirement for solder to have a predetermined strength.

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

[Prior Technical Literature] [Patent Literature]

(Patent Document 1) JP 2001-77521 A

The solder that connects the two electrodes after the reflow process sometimes contains so-called voids. The air bubbles are formed in the voids in the solder, and the voids are filled with gas formed by the vaporization of the resin component of the flux and the solvent of the flux. If bubbles are formed, the resistance between the two electrodes will rise, and there is a possibility that proper electrical connection cannot be ensured. In addition, air bubbles are also the cause of the decrease in the strength of the solder, and there is a possibility that the electrical connection between the two electrodes cannot be maintained in the event of impact. Smaller bubbles are less likely to cause the above problems. The bubbles that cause the above problems are relatively large bubbles. Therefore, in the technical field of surface mounting, the requirement for the generated bubbles is to suppress the size of the bubbles.

The present invention was made in view of the above-mentioned problems, and its object is to provide a solder paste coating method and a mask that can suppress the size of bubbles even when bubbles are formed in solder during surface mounting.

In order to solve the aforementioned problems, the present invention adopts the following means.

The first aspect of the present invention is a coating method for applying solder paste to an object to be coated, including a procedure of applying solder paste to the coating area in a manner that forms a non-coating area in the bonding area of the object to be coated , Wherein at least a part of the coating area is located in the bonding area, and the coating area has a plurality of peripheral areas arranged at intervals in a circumferential direction surrounding the center of the bonding area.

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

In the first aspect of the present invention, the plurality of peripheral regions may extend and be arranged in a direction intersecting the opposing direction of the plurality of peripheral regions.

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

In the first aspect of the present invention, the gap between the plurality of peripheral regions may be 85.7% or more and 200% or less of the width of each peripheral region in the opposing direction of the plurality of peripheral regions.

In the first aspect of the present invention, the number of the plurality of peripheral regions may be 2 to 6.

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 may have a first region and a second region whose lengths in the circumferential direction are different, and the first region and the second region may alternate in the circumferential direction. Configuration.

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

In the aforementioned first aspect of the present invention, the aforementioned coating area may further have a central area located at the radial inner side of the aforementioned plurality of peripheral areas.

In the first aspect of the present invention, the opposite sides of the central area and the peripheral areas may be parallel to each other.

In the first aspect of the present invention, the area of the central region may be 44.4% to 278% of the area of each peripheral region.

In the aforementioned first aspect of the present invention, the aforementioned plurality of peripheral regions may be partially connected and arranged.

In the aforementioned first aspect of the present invention, the width in the circumferential direction of each peripheral area may gradually increase from the center of the joint area toward the outside in the radial direction.

In the first aspect of the present invention, the ratio of the gaps between the plurality of peripheral regions that open from the center of the bonding region toward the radially outer side relative to the entire circumference of the bonding region may be 11.5% or more.

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

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

The second aspect of the present invention is a coating method for applying solder paste to an object to be coated, including: applying the solder paste to a non-coating area in the bonding area of the object to be coated The procedure of the coating area, wherein at least a part of the coating area is located in the bonding area, and the coating area has an extension area that includes the center of the bonding area and extends in a single direction.

In the second aspect of the present invention, the extension area may be arranged to overlap the outer edge of the bonding area.

In the aforementioned second aspect of the present invention, the aforementioned extension area may be disposed in the aforementioned bonding area.

In the second aspect of the present invention, the coating area may further have a plurality of side areas arranged with the extension area interposed in a direction intersecting the longitudinal direction of the extension area.

In the aforementioned second aspect of the present invention, the opposite sides of the aforementioned extension area and each side area may be parallel to each other.

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

In the aforementioned second aspect of the present invention, the aforementioned plurality of side areas may be arranged in the aforementioned joint area.

The third aspect of the present invention is a mask used in the solder paste coating method of the first or second aspect, which is formed with an opening at a position corresponding to the coating area.

According to the aforementioned aspect of the present invention, even if bubbles are formed in the solder during surface mounting, the size of the bubbles can be suppressed. Therefore, it is possible to provide: a suitable electrical connection between the coated object such as a substrate and the electrodes on both sides of the electronic component can be ensured, and the strength of the solder that connects the electrodes on both sides can be prevented from being reduced, and the surface is shock-resistant After mounting the board, etc.

A1‧‧‧ Surrounding area

A2‧‧‧Central area

A3‧‧‧Extended area

A4‧‧‧Side area

A11‧‧‧First area

A12‧‧‧Second area

a,b‧‧‧the opposite side

B‧‧‧Substrate (coating object)

G‧‧‧Interval

L1,L2,L3‧‧‧Straight

N‧‧‧Non-coated area

O‧‧‧ Center

P‧‧‧Pad (joining area)

S‧‧‧Solder Paste

T‧‧‧coating area

Fig. 1 is a schematic diagram showing a solder printing apparatus related to an embodiment of the present invention.

Fig. 2A is a plan view of a substrate as an object to be coated according to an embodiment of the present invention.

Fig. 2B is a plan view of a mask used for screen printing according to an embodiment of the present invention.

Fig. 3 is a schematic diagram showing each procedure of the solder paste coating method according to one embodiment of the present invention.

Figure 4 is a schematic diagram showing the procedure after the solder paste application procedure in the entire surface mounting process.

Fig. 5 is a plan view showing the application area of the solder paste in Example 1.

Fig. 6 is a plan view showing the application area of the solder paste in Example 2.

Fig. 7 is a plan view showing the application area of the solder paste in Example 3.

Fig. 8 is a plan view showing the application area of the solder paste in Example 4.

Fig. 9 is a plan view showing the application area of the solder paste in Example 5.

Fig. 10 is a plan view showing the application area of the solder paste in Example 6.

Fig. 11 is a plan view showing the application area of the solder paste in Example 7.

Figure 12 is a plan view showing the application area of the solder paste in Example 8.

Fig. 13 is a plan view showing the application area of the solder paste in Example 9.

Fig. 14 is a plan view showing the application area of the solder paste in Example 10.

Fig. 15 is a plan view showing the application area of the solder paste in Example 11.

FIG. 16 is a plan view showing the application area of the solder paste in Example 12.

Fig. 17 is a plan view showing the application area of the solder paste in Example 13.

Fig. 18 is a plan view showing the application area of the solder paste in Example 14.

Figure 19 is a plan view showing the application area of the solder paste in Example 15.

FIG. 20 is a plan view showing the application area of the solder paste in Example 16.

Fig. 21 is a plan view showing the application area of the solder paste in Example 17.

Fig. 22 is a plan view showing the application area of the solder paste in Example 18.

FIG. 23 is a plan view showing the application area of the solder paste in Example 19.

FIG. 24 is a plan view showing the application area of the solder paste in Example 20.

Fig. 25 is a plan view showing the application area of the solder paste in Example 21.

FIG. 26 is a plan view showing the application area of the solder paste in Example 22. FIG.

Fig. 27 is a plan view showing the application area of the solder paste in Example 23.

FIG. 28 is a plan view showing the application area of the solder paste in Example 24. FIG.

Fig. 29 is a plan view showing the application area of the solder paste in Example 25.

FIG. 30 is a plan view showing the application area of the solder paste in Example 26.

Hereinafter, the solder printing apparatus and the solder paste application method related to an embodiment of the present invention will be described with reference to the accompanying drawings.

The solder printing apparatus 1 of this embodiment is a screen printing apparatus using a mask M. As shown in Fig. 1, the solder printing apparatus 1 is provided with: a substrate support 2 supporting a substrate B as an object to be coated with solder paste S; a printing unit 3 arranged directly above the substrate support 2; and a housing substrate support Section 2 and the housing 4 of the printing section 3. The mask M is held at a predetermined position in the casing 4 by a mask support portion (not shown) fixed to the casing 4 and the like.

The substrate support portion 2 is provided with: a platform 21 that supports the substrate B from directly below so that its mounting surface faces directly upward; and allows the platform 21 to be movable in the horizontal and vertical directions and centered on an axis extending in the vertical direction Rotating platform moving part 22. The platform 21 is provided with a clamping member 23 for holding the substrate B. In addition, the solder printing apparatus 1 is provided with a board conveying unit (not shown) for conveying the board B in and out between the board supporting unit 2 and the outside of the housing 4.

The printing section 3 is provided with: a squeegee 31 for moving the solder paste S on the surface (upper surface) of the mask M; a vertical movement device 32 that allows the squeegee 31 to be raised and lowered, and a vertical movement device 32 Horizontal moving device 33 that can move horizontally. The squeegee 31 is a member that can move in the +X direction in the horizontal direction while contacting the surface of the mask M, and is used to push the solder paste S supplied to the mask M out. The scraper 31 is connected to the vertical movement device 32. The squeegee 31 may be a plate member made of a single material such as metal, resin, rubber, etc., or a plate member formed by covering a part of a metal plate, etc., that is to be in contact with the mask M with resin or rubber . The squeegee 31 is arranged to be inclined downward toward the X direction which is opposite to the +X direction. The inclination angle of the scraper 31 can be adjusted 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 to the surface of the mask M with a predetermined force. The horizontal moving device 33 is fixed on the housing 4 and is provided with: a linear guide 34 that guides the vertical moving device 32 in the horizontal direction; and a motor 35 that rotates a ball screw (not shown) arranged in parallel with the linear guide 34 . The horizontal moving device 33 is driven by the motor 35 to move the vertical moving device 32 connected to the ball screw through the nut member in the horizontal direction. The horizontal moving device 33 moves the vertical moving device 32 in the horizontal direction when the vertical moving device 32 causes the scraper 31 to press down on the mask M, so that the scraper 31 can press the mask M while pressing Move horizontally. In addition, the solder printing apparatus 1 is provided with a dispenser (not shown) for supplying the solder paste S to the mask M.

The housing 4 has sufficient rigidity to support the aforementioned mask support part and the printing part 3. The housing 4 may be configured to have a structure capable of making its inside airtight. In addition, when the solder paste S is to be applied under a reduced pressure environment, an exhaust device such as a vacuum pump and a valve for opening and closing the atmosphere can be installed in the housing 4.

FIG. 2A is a plan view of the substrate B, and FIG. 2B is a plan view of the mask M. The "plan view" in this specification refers to a view seen from a direction perpendicular to the mounting surface of the substrate B and the upper surface of the mask M.

As shown in Figure 2A, the substrate B to be coated with solder paste S in this embodiment is a printed circuit board composed of a rigid plate-shaped substrate, and a plurality of pads are arranged on at least one side of the board. ) P (electrode, junction area). The board surface on this side is the mounting surface where the electronic component E described later is to be mounted. Examples of the material of the pad P include copper, gold, and silver. In the mounting surface of the substrate B, regions other than the plurality of pads P are coated with a solder resist having a property of repelling molten solder.

As shown in FIG. 2B, the mask M used in this 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 in the range of, for example, 30 μm to 200 μm, and can be appropriately changed depending on how thick the solder paste S is applied on the substrate B. In the conventional screen printing mask, an opening of the same size as the pad is formed at a position corresponding to the pad of the substrate. The opening H of this embodiment has a different plan view from the pad P of the substrate B The shape. That is, the opening H formed in the mask M of this embodiment is used to apply the solder paste S to at least a part of the solder paste S in a manner that forms a non-coating area in the solder pad P on the substrate B. The opening of the coating area in P. In other words, an opening H of the same shape is formed at a position corresponding to the application area. The shape of the opening H in the mask M of the present embodiment, that is, the shape of the application area of the solder paste S to be applied to the substrate B, will be described in detail using Examples 1 to 26 described later. Figure 2B In the mask M shown, two rectangular openings H are formed corresponding to one pad P, and the two openings H are arranged opposite to each other with the center of the pad P interposed therebetween.

The solder paste S used in this embodiment is not particularly limited, and can be appropriately selected according to the application environment, temperature, the size and shape of the opening of the mask M, and the like. As mentioned above, the solder paste is made by mixing solder powder with flux. The solder powder can be copper, tin, silver, and alloys of the metals listed above, and the shape of the solder powder can be spherical or indefinite. The flux includes, for example, resin such as rosin, a solvent used to adjust viscosity, an active agent used to clean the electrode surface, and a thixotropic agent used to adjust viscosity, adhesion, and thixotropy. The content of etc. can be adjusted appropriately according to the state of use.

Next, with reference to FIG. 3, the coating method of the solder paste S using the solder printing apparatus 1 of this embodiment is demonstrated. In Fig. 3, the configuration of the solder printing device 1 other than the squeegee 31 is omitted.

The substrate B is placed on the platform 21 by the aforementioned substrate conveying part, and the substrate B is held on the platform 21 by the clip member 23. Next, the movement of the platform moving part 22 is used to adjust the horizontal position of the substrate B relative to the fixed mask M and the rotation position centered on the axis extending in the vertical direction. Then, the platform moving part 22 moves the platform 21 from Fig. 3 The state shown in (a) ascends until the upper surface (mounting surface) of the substrate B is in close contact with the lower surface of the mask M as shown in FIG. 3(b). At this time, since the horizontal position and rotation position of the substrate B have been adjusted by the platform moving part 22 first, the opening H of the mask M will be arranged at an appropriate position relative to the pad P of the substrate B. That is, when the surface of the substrate B on which the pads P are provided is in contact with the mask M, the area of the substrate B (coating area) where the solder paste S is to be applied in the mask M corresponds (opposite) The position will be formed with an opening H.

Next, as shown in FIG. 3(c), the solder paste S is supplied to the mask M through which the squeegee 31 will pass, that is, the +X side of the squeegee 31, by using the aforementioned dispenser. Moreover, using the vertical movement device 32 The squeegee 31 is driven to descend, and the mask M is pressed downward with a predetermined force. In this state, the horizontal moving device 33 moves the vertical moving device 32 in the +X direction, and the squeegee 31 moves in the +X direction while keeping the mask M pressed. Because the solder paste S is supplied to the position where the squeegee 31 is about to pass, the solder paste S moves in the +X direction as the squeegee 31 moves. In addition, the squeegee 31 is inclined as described above, so as the squeegee 31 moves, a vertical downward force acts on the solder paste S. Therefore, as shown in FIG. 3(d), the solder paste S is pressed to fill the opening H of the mask M and contact the upper surface (mounting surface) of the substrate B. Furthermore, since the squeegee 31 moves in the +X direction while pressing the mask M downwards, the solder paste S can be scraped off and moved from the upper surface of the mask M other than the opening H, so that the solder paste S can only be removed. Supply to opening H. The horizontal movement of the squeegee 31 driven by the horizontal movement device 33 ends, as shown in FIG. 3(e), the filling of the solder paste S for the plurality of openings H of the mask M is completed.

Next, as shown in FIG. 3(f), the stage moving part 22 lowers the stage 21 to move the substrate B downward and away from the lower surface of the mask M. At this time, because the solder paste S filled into the opening H will adhere to the upper surface of the substrate B, the solder paste S will also be separated from the mask M, so the mounting surface of the substrate B is printed with the mask M The solder paste S of the pattern corresponding to the opening H. Because the opening H of the mask M has a shape as shown in FIG. 2B, the solder paste coating method of this embodiment includes: forming a non-coated area in the pad P on the substrate B. The paste S is applied to at least a part of the application area located in the pad P. The substrate B is separated from the lower surface of the mask M, the solder paste S is printed on the substrate B, and the solder paste application procedure of this embodiment is completed. The substrate B coated with the solder paste S is carried out from the solder printing apparatus 1 by the above-mentioned substrate transport section.

Next, referring to Fig. 4, the procedure after the solder paste application procedure of this embodiment of the entire surface mounting process will be described.

First, as shown in Fig. 4(a), the electronic component E is placed on the mounting surface of the substrate B coated with the solder paste S. The electronic component E can be LGA or BGA. On the bottom surface (the surface facing the substrate B) of the electronic component E, a plurality of land surfaces L (electrodes) corresponding to the plurality of pads P of the substrate B are provided. The program shown in Fig. 4(a) is to mount the electronic component E on the substrate B so that the pad P of the substrate B will face the land L of the electronic component E. 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.

Next, as shown in Fig. 4(b), the substrate B on which the electronic component E is mounted is heated by a reflow furnace (not shown) to melt the solder powder in the solder paste S and combine, and the molten solder It will contact the electrodes on both sides of the substrate B and the electronic component E. At this time, due to the effect of the flux contained in the solder paste S, the wettability of the molten solder to the pad P will be improved. In addition, since the surface of the substrate B other than the pad P is coated with a solder resist that repels the molten solder, it melts The solder flows toward the inner side of the pad P in the radial direction. That is, even if the solder paste S is applied to two areas as in the present embodiment, the solder in the two areas will be integrated in the reflow process. Then, the molten solder cools and solidifies, and the electrodes on both sides of the substrate B and the electronic component E are electrically connected to each other under the connection of the solder S1. After the above procedure, the surface mounting of the electronic component E on the substrate B is completed.

Next, a plurality of specific examples of the solder paste application method of this embodiment will be described with reference to the drawings. In addition, in order to compare with these examples, a comparative example equivalent to the conventional coating method was also discussed.

The following Examples 1 to 26 use Figures 5 to 30 of the plan view showing the mounting surface of the substrate B to illustrate the solder paste application area. Each plan view is an enlarged display of one pad P of the substrate B as an example of the bonding area之图. In each embodiment, the shape of the pad P as seen from a plan view is a circle with a diameter of 1.0 mm. In the following description, it will intersect the axis passing through the center of the pad P and perpendicular to the mounting surface of the substrate B The direction of the fork is called the radial direction, and the direction around the axis is called the circumferential direction. In addition, for convenience, the up-down direction on the paper of each figure is sometimes referred to as the "up and down direction", and the left-right direction on the paper is sometimes referred to as the "left-right direction".

In these Examples and Comparative Examples, the gap ratio GR, the coating area ratio AR, and the maximum bubble area ratio VR described below were confirmed.

The gap ratio GR refers to the ratio of the gap between a plurality of peripheral regions A1 to be described later that opens from the center of the pad P toward the radially outer side with respect to the entire circumference of the pad P. In other words, if only two straight lines extending from the center of the pad P to the radially outer side without any peripheral area A1 between them can be drawn, the ratio of the angle between the two straight lines to 360° is the gap ratio GR . If two straight lines that do not include the peripheral area A1 in between can draw multiple pairs, the gap ratio GR is the ratio of the sum of the angles between the two straight lines in each pair relative to 360°. In the calculation of the gap ratio GR, the existence of the central area A2 described later is not considered.

The coating area ratio AR refers to the ratio of all coating areas of the solder paste applied to one solder pad P to the area of the solder pad P. The pi ratio is 3.14.

The calculation of the maximum bubble area rate VR is to prepare two test substrates each with 36 pads P for each embodiment, and respectively perform solder connection with electronic components with the same number of lands. For each example, a total of 72 solder connection samples of the pads P were obtained. For this solder connection, the surface mounting method shown in Figure 3 and Figure 4 is used. For 72 pads P, calculate the ratio of the bubble area (area seen from the plan view) to the area of one pad P (hereinafter referred to as the bubble area rate), and take the largest bubble area rate As the "maximum bubble area ratio" of each example. The shape of the land surface of the electronic component as seen from the plan view is made substantially the same as the pad P.

(Comparative example)

The comparative example adopts a conventional structure in which solder paste is applied to a pad P with a diameter of 1.0 mm in the same area as the pad P. This comparative example is represented by "Ref" in Table 1 below. In this comparative example, since there are no plural peripheral regions, the gap ratio GR cannot be calculated, and the coating area ratio AR is 100%. In addition, the maximum bubble area ratio VR is 43.5%.

(Example 1)

The application area of the solder paste in Example 1 will be described with reference to FIG. 5.

In the first embodiment, a non-coating area N is formed in the solder pad P on the substrate B, and the solder paste is applied to at least a part of the coating area T located in the solder pad P. In Figure 5, dots are added to the area where the solder paste is applied (this is the same in Figures 6 to 30). The coating area T has a plurality of (two) peripheral areas A1 arranged at intervals G in the circumferential direction around the center O of the pad P. Each peripheral area A1 is a rectangle extending in a single direction, the length in the long side direction is 0.7 mm, and the width in the short side direction orthogonal to the long side direction is 0.35 mm.

The plurality of peripheral regions A1 are arranged opposite to each other with the center O of the pad P interposed therebetween.

The plurality of peripheral regions A1 are arranged to extend in a direction orthogonal to the opposing direction of the plurality of peripheral regions A1 (the vertical direction of the paper in FIG. 5). That is, each peripheral area A1 extends in the left-right direction on the paper surface. A plurality of peripheral regions A1 may extend in a direction intersecting the aforementioned opposing direction.

The size of the gap between the plurality of peripheral regions A1 (the aforementioned gap in the opposing 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 200% of the width of each peripheral region A1 in the aforementioned opposing direction.

The plurality of peripheral areas A1 are arranged at equal intervals in the circumferential direction. In addition, a plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The opposite sides a and b of the plurality of peripheral areas A1 are parallel to each other. In addition, the opposite sides a and b may not be parallel.

The plurality of peripheral regions A1 are arranged to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located outside the pad P in the radial direction. In addition, the plurality of peripheral areas A1 may also be configured to be all arranged in the pad P.

In the case where the coating area T of this embodiment is divided into four blocks by two straight lines passing through the center O and extending in the up-down direction and the left-right direction, for example, the straight line L1 extending from the center O to the right side of the paper is different from the center O The block between the straight line L2 extending to the upper side of the paper has the same or mirror image relationship with the other three blocks, so the ratio of the angle θ _G to the 90° included angle between the straight lines L1 and L2 is taken as the gap ratio of this embodiment GR. Here, the angle θ _G is the angle between the straight line L1 and the straight line L3 extending from the center O to the radially outer side and tangent to the lower right vertex of the peripheral area A1 on the upper side of the paper. The peripheral area A1 is not arranged between the straight lines L1 and L3. Therefore, the gap ratio GR of this embodiment is (arctan(0.35/0.35)/90°)=50%.

The coating area ratio AR of this embodiment is (0.7×0.35×2)/(0.5 ² ×π)=62.4%.

The maximum bubble area ratio of this embodiment is 2.3%.

(Example 2)

The application area of the solder paste in Example 2 will be described with reference to FIG. 6. In the following description of the second embodiment, only the configuration that is different from the foregoing embodiment 1 will be described, and the description of the other configurations will be omitted.

The size of the gap between the plurality of peripheral regions A1 (the aforementioned gap in the opposing 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 85.7% of the width of each peripheral region A1 in the aforementioned opposing direction.

The gap ratio GR of this embodiment is (arctan(0.15/0.35)/90°)=25.8%.

The maximum bubble area ratio of this embodiment is 13.8%.

(Example 3)

The application area of the solder paste in Example 3 will be described with reference to FIG. 7. In the following description of Embodiment 3, only the configuration that is different from the foregoing Embodiment 1 will be described, and the description of other configurations will be omitted.

The size of the gap between the plurality of peripheral regions A1 (the aforementioned gap in the opposing direction) 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 114% of the width of each peripheral region A1 in the aforementioned opposing direction.

The gap ratio GR of this embodiment is (arctan(0.2/0.35)/90°)=33%.

The maximum bubble area ratio of this embodiment is 11.7%.

(Example 4)

The application area of the solder paste of Example 4 will be described with reference to FIG. 8. In the following description of Embodiment 4, only the configuration that is different from the foregoing Embodiment 1 will be described, and the description of other configurations will be omitted.

The size of the gap between the plurality of peripheral regions A1 (the aforementioned gap in the opposing 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 143% of the width of each peripheral region A1 in the aforementioned opposing direction.

The gap ratio GR of this embodiment is (arctan(0.25/0.35)/90°)=39.5%.

The maximum bubble area ratio of this embodiment is 7.0%.

(Example 5)

The application area of the solder paste in Example 5 will be described with reference to Fig. 9. In the following description of Embodiment 5, only the configuration that is different from the foregoing Embodiment 1 will be described, and the description of other configurations will be omitted.

The size of the gap between the plurality of peripheral regions A1 (the aforementioned gap in the opposing 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 171% of the width of each peripheral region A1 in the aforementioned opposing direction.

The gap ratio GR of the embodiment is (arctan(0.3/0.35)/90°)=45.1%.

The maximum bubble area ratio of this embodiment is 4.2%.

(Review of Examples 1 to 5)

The maximum bubble area ratio VR of Examples 1 to 5 is lower than that of Comparative Example. From this, it can be seen that all of Examples 1 to 5 can suppress the size of bubbles generated in the solder paste.

The reason for suppressing the size of bubbles is discussed below. When the molten solder powder is combined in the reflow process, the resin component of the flux between the solder powder before the melting is pushed out due to the combination of the molten solder. However, if the application area of the solder paste is large, it will happen that the aforementioned resin component is too late to be discharged from the solder and the solder has cooled and solidified, so the resin component will remain in the solder (that is, bubbles are formed). As for Examples 1 to 5, the width of each peripheral area A1 is 0.35 mm, which is much smaller than the maximum diameter (1.0 mm) of the pad P. Therefore, when the resin component of the flux moves in the short-side direction of the peripheral area A1, it is discharged from the molten solder more quickly. Therefore, in each peripheral area A1, the size of bubbles is suppressed compared to the comparative example.

In addition, as shown in Figure 4, the solder powder applied in the solder paste in the two areas will also be 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 is combined near the center of the pad P. Because the molten solder continues to flow radially inward during the reflow process, the joint portion of the molten solder flowing from the two regions will expand radially outward. Since this connection part expands radially outward, there is a force that causes the resin component of the flux to move radially outward, and this force can also discharge the resin component to the outside of the solder.

In Examples 1 to 5, the gap between the plurality of peripheral regions A1 is 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 is 85.7% to 200% of the width of each peripheral region A1 in the opposing direction of the plurality of peripheral regions A1.

(Modifications of Examples 1 to 5)

Examples 1 to 5 can consider the following modifications.

Although the shape of each peripheral area A1 is rectangular when viewed from a plan view, it may be oval or oblong when viewed from a plan view. Although the opposing sides a and b of the plurality of peripheral regions A1 are formed in a linear shape, the two opposing sides may be convex inward in the radial direction or concave in the radial outward direction. Similarly, the radially outer side of the peripheral area A1 may be concave toward the radially inner side or convex toward the radially outer side.

(Example 6)

The application area of the solder paste in Example 6 will be described with reference to Fig. 10.

In the sixth embodiment, the non-coating area N is formed in the solder pad P on the substrate B, and the solder paste is applied to at least a part of the coating area T located in the solder pad P. The coating area T has a plurality of (six) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a square with a side length of 0.3 mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 10.

The plurality of peripheral regions A1 are arranged at substantially equal intervals in the circumferential direction. In addition, the plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

Opposing sides a and b of a plurality of peripheral regions A1 adjacent in the circumferential direction are parallel to each other. In addition, the opposite sides a and b may not be parallel to each other.

The opposite sides c and d of the central area A2 and the peripheral areas A1 are parallel to each other. In addition, the opposite sides c and d may not be 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 regions A1 are arranged to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located outside the pad P in the radial direction. In addition, the plurality of peripheral areas A1 may also be configured to be all arranged in the pad P.

In the case where the coating area T of this embodiment is divided into four blocks by two straight lines passing through the center O and extending in the up-down direction and the left-right direction, for example, the straight line L1 extending from the center O to the right side of the paper is different from the center O The block between the straight line L2 extending to the upper side of the paper has the same or mirror image relationship with the other three blocks, so the ratio of the sum of the angle θ _G1 and the angle θ _G2 to the 90° included angle between the straight lines L1 and L2 is taken as The gap ratio GR of this embodiment. The angle θ _G1 is the angle between the straight line L1 and the straight line L3 extending from the center O to the radially outer side and tangent to the lower right vertex of the upper right peripheral area A1 on the paper surface, and can be expressed as arctan (0.1/0.65). The angle θ _G2 is a straight line L4 extending radially outward from the center O and tangent to the upper left vertex of the peripheral area A1 on the upper right of the paper, and the lower right vertex of the peripheral area A1 extending radially outward from the center O and on the upper right of the paper. The angle between the tangent lines L5 can be expressed as (arctan(0.35/0.15)-arctan(0.4/0.35)). Therefore, the gap ratio GR of this embodiment is (θ _G1 +θ _G2 )/90°=29.7%.

The coating area ratio AR of this embodiment is (0.3 ² ×7)/(0.5 ² ×π)=80.3%.

The maximum bubble area ratio of this embodiment is 4.8%.

(Example 7)

The application area of the solder paste in Example 7 will be described with reference to FIG. 11. In the following description of the seventh embodiment, only the configuration that is different from the foregoing embodiment 6 will be described, and the description of the other configurations will be omitted.

The central area A2 is a square with a side length of 0.4mm. The center area A2 is arranged so that its center coincides with the center O of the pad P when viewed in plan. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 11.

The area of the central area A2 is 178% (=0.4 ² /0.3 ² ) of the area of each peripheral area A1.

The gap ratio GR of this embodiment is the same as that of the aforementioned embodiment 6, which is 29.7%.

The coating area ratio AR of this embodiment is (0.3 ² ×6+0.4 ² )/(0.5 ² ×π)=89.2%.

The maximum bubble area ratio of this embodiment is 3.9%.

(Example 8)

The application area of the solder paste in Example 8 will be described with reference to Fig. 12. In the following description of the eighth embodiment, only the configuration different from that of the aforementioned embodiment 6 will be described, and the description of the other configurations will be omitted.

The central area A2 is a square with a side length of 0.5mm. The center area A2 is arranged so that its center coincides with the center O of the pad P when viewed in plan. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 12.

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 this embodiment is the same as that of the aforementioned embodiment 6, which is 29.7%.

The coating area ratio AR of this embodiment is (0.3 ² ×6+0.5 ² )/(0.5 ² ×π)=100.6%.

The maximum bubble area ratio of this embodiment is 13.9%.

(Example 9)

The application area of the solder paste in Example 9 will be described with reference to FIG. 13. In the following description of the ninth embodiment, only the configuration that is different from the foregoing embodiment 6 will be described, and the description of the other configurations will be omitted.

The central area A2 is a square with a side length of 0.2mm. The center area A2 is arranged so that its center coincides with the center O of the pad P when viewed in plan. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 13.

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 this embodiment is the same as that of the aforementioned embodiment 6, which is 29.7%.

The coating area ratio AR of this embodiment is (0.3 ² ×6+0.2 ² )/(0.5 ² ×π)=73.9%.

The maximum bubble area ratio of this embodiment is 12.3%.

(Example 10)

The application area of the solder paste of Example 10 will be described with reference to Fig. 14. In the following description of Embodiment 10, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (two) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a square with a side length of 0.3 mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 14.

The plural peripheral regions A1 are arranged at equal intervals in the circumferential direction. The plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The 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 not be parallel to each other.

In the case where the coating area T of this embodiment is divided into four blocks by two straight lines passing through the center O and extending in the up-down direction and the left-right direction, for example, the straight line L1 extending from the center O to the right side of the paper is different from the center O The block between the straight line L2 extending to the upper side of the paper has the same or mirror image relationship with the other three blocks, so the ratio of the angle θ _G to the 90° included angle between the straight lines L1 and L2 is taken as the gap ratio of this embodiment GR. Here, the angle θ _G is the angle between the straight line L1 and the straight line L3 extending from the center O to the radially outer side and tangent to the lower right vertex of the peripheral area A1 on the upper side of the paper. The peripheral area A1 is not arranged between the straight lines L1 and L3. Therefore, the gap ratio GR of this embodiment is (arctan(0.35/0.15)/90°)=74.2%.

The coating area ratio AR of this embodiment is (0.3 ² ×3)/(0.5 ² ×π)=34.4%.

The maximum bubble area ratio of this example is 3.1%.

(Example 11)

The application area of the solder paste in Example 11 will be described with reference to FIG. 15. In the following description of Embodiment 11, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (three) 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 on the radial inner side of the plurality of peripheral areas A1. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 15.

The plurality of peripheral regions A1 are arranged at substantially equal intervals in the circumferential direction. The plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. It may also be that the opposite sides a and b are not parallel to each other.

In the case where the coating area T of this embodiment is divided into two blocks by a straight line passing through the center O and extending in the up and down direction, since the block on the right of the straight line is a mirror image of the block on the left, the angle θ _G1 and The ratio of the sum of θ _G2 and θ _G3 to the 180° included angle between the straight line L1 extending upward from the center O and the straight line L2 extending downward from the center O serves as the gap ratio GR of the present embodiment. Among them, the angle θ _G1 is the angle between a straight line L3 extending from the center O to the right side of the paper and a straight line L4 extending from the center O to the radially outer side and tangent to the lower right vertex of the peripheral area A1 on the upper side of the paper. Into arctan(0.35/0.15). The angle θ _G2 is the angle between the straight line L2 and the straight line L5 extending from the center O to the radially outer side and tangent to the lower left vertex of the lower right peripheral area A1 on the paper, and can be expressed as (90°-arctan(0.45/0.35 )). The angle θ _G3 is the angle between the straight line L3 and the straight line L6 extending from the center O radially outward and tangent to the upper right vertex of the lower right peripheral area A1 on the paper, and can be expressed as arctan (0.15/0.65)). Therefore, the gap ratio GR of this embodiment is (θ _G1 +θ _G2 +θ _G3 )/90°=65.4%.

The coating area ratio AR of this embodiment is (0.3 ² ×4)/(0.5 ² ×π)=45.9%.

The maximum bubble area ratio of this embodiment is 4.0%.

(Example 12)

The application area of the solder paste in Example 12 will be described with reference to Fig. 16. In the following description of Embodiment 12, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (four) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a square with a side length of 0.3 mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 16.

The plural peripheral regions A1 are arranged at equal intervals in the circumferential direction. The plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. It may also be that the opposite sides a and b are not parallel to each other.

In the case where the coating area T of this embodiment is divided into four blocks by two straight lines passing through the center O and extending in the up-down direction and the left-right direction, for example, the straight line L1 extending from the center O to the right side of the paper is different from the center O The block between the straight line L2 extending to the upper side of the paper has the same or mirror image relationship with the other three blocks, so the ratio of the angle θ _G to the 90° included angle between the straight lines L1 and L2 is taken as the gap ratio of this embodiment GR. Among them, the angle θ _G is a straight line L3 extending from the center O to the radially outer side and tangent to the upper left vertex of the peripheral area A1 on the right side of the paper, and is connected to the right of the peripheral area A1 extending from the center O to the radially outer side and on the upper side of the paper The angle between the lines L4 whose lower vertices are tangent. The peripheral area A1 is not arranged between the straight lines L3 and L4. Therefore, the gap ratio GR of this embodiment is (arctan(0.35/0.15)-arctan(0.15/0.35))=48.4%.

The coating area ratio AR of this embodiment is (0.3 ² ×5)/(0.5 ² ×π)=57.1%.

The maximum bubble area ratio of this embodiment is 2.6%.

(Example 13)

The application area of the solder paste in Example 13 will be described with reference to FIG. 17. In addition, in the following description of the thirteenth embodiment, only the configuration different from that of the aforementioned embodiment 6 will be described, and the description of the other configurations will be omitted.

The coating area T has a plurality of (four) 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 on the radial inner side of the plurality of peripheral areas A1. In addition, the plurality of peripheral areas A1 have a first area A11 and a second area A12 having different lengths in the circumferential direction, and the first area A11 and the second area A12 are alternately arranged in the circumferential direction. There are two first areas A11 and two second areas A12. The first area A11 is a rectangle extending in a single direction, the length in the long side direction is 0.6 mm, and the width in the short side direction orthogonal to the long side direction is 0.3 mm. Both the second area A12 and the central area A2 are squares with a side length of 0.3 mm. Central area A2 system The center is set to coincide with the center O of the pad P in plan view. The mutual positional relationship between the plurality of first areas A11 and the plurality of second areas A12 and the central area A2 is as shown in FIG. 17.

The opposite sides a and b of the central area A2 and the peripheral areas A1 are parallel to each other. It may also be that the opposite sides a and b are not parallel to each other.

The gap ratio GR of the present embodiment is calculated in the same manner as in the foregoing embodiment 12, and is (arctan(0.35/0.15)-arctan(0.3/0.35))=29.1%.

The coating area ratio AR of this embodiment is (0.6×0.3×2+0.3 ² ×3)/(0.5 ² ×π)=34.6%.

The maximum bubble area ratio of this embodiment is 1.8%.

(Example 14)

The application area of the solder paste in Example 14 will be described with reference to FIG. 18. In addition, in the following description of Embodiment 14, only the configuration different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (six) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a square with a side length of 0.3 mm. However, the actual shape of the peripheral area A1 is a shape obtained by cutting away a portion located on the radially outer side of the outer edge of the pad P from a square. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 18.

Opposing sides a and b of a plurality of peripheral regions A1 adjacent in the circumferential direction are parallel to each other. It may also be that the opposite sides a and b are not parallel to each other.

The opposite sides c and d of the central area A2 and the peripheral areas A1 are parallel to each other. It can also be that the opposite sides c and d are not parallel to each other.

The gap ratio GR of this embodiment is calculated by the same method as the above-mentioned Embodiment 6, but the angle θ _G1 is arcsin (0.05/0.5), so the gap ratio GR is (θ _G1 +θ _G2 )/90°=11.5%.

The coating area ratio AR of this example is about 43%.

The maximum bubble area ratio of this embodiment is 13.8%.

(Review of Examples 6-14)

The maximum bubble area ratio VR of Examples 6 to 14 is lower than that of Comparative Example. From this, it can be seen that all Examples 6 to 14 can suppress the size of bubbles generated in the solder paste.

The reason for suppressing the size of bubbles is discussed below. First, the peripheral area A1 and the central area A2 are both smaller than the coating area of the comparative example, so the resin component of the flux is easily and quickly discharged from the molten solder. This point is the same as in Examples 1 to 5.

In addition, although Examples 6 to 14 all have a central area A2, the solder powder applied in the solder paste in the central area A2 flows radially outward after melting. Regarding the central area of each of Examples 6-14, all open from the center O toward the radial outside through the gap G, so the same is to calculate the plural peripheries that open from the center O of the pad P to the radial outside The ratio of the gap between the regions A1 to the entire circumference of the pad P is defined as the gap ratio GR. Therefore, the molten solder flowing out from the central area A2 can flow appropriately to the radially outer side through the gap G, so that the resin component of the flux can be discharged to the radially outer side.

In Examples 6 to 14, the area of the central area A2 was 44.4% to 278% of the area of each peripheral area A1.

(Example 15)

The application area of the solder paste in Example 15 will be described with reference to Fig. 19. In addition, in the following description of the fifteenth embodiment, only the configuration that is different from the aforementioned embodiment 12 will be described, and the description of the other configurations will be omitted.

Example 15 has a configuration in which the central area A2 is removed from Example 12.

The gap ratio GR of this example is the same as that of Example 12, which is 48.4%.

The coating area ratio AR of this embodiment is (0.3 ² ×4)/(0.5 ² ×π)=45.7%.

The maximum bubble area ratio of this embodiment is 13.4%.

(Example 16)

The application area of the solder paste in Example 16 will be described with reference to Fig. 20. In addition, in the following description of the 16th embodiment, only the configuration different from the aforementioned embodiment 13 will be described, and the description of the other configurations will be omitted.

Example 16 has a configuration in which the central area A2 is removed from Example 13.

The gap ratio GR of this example is the same as that of Example 13, and is 29.1%.

The coating area ratio AR of this embodiment is (0.6×0.3×2+0.3 ² ×2)/(0.5 ² ×π)=23.2%.

The maximum bubble area ratio of this embodiment is 13.8%.

(Review of Examples 15 and 16)

The maximum bubble area ratio VR of Examples 15 and 16 is lower than that of Comparative Example. From this, it can be seen that both Examples 15 and 16 can suppress the size of bubbles generated in the solder paste.

Discuss the reason why the size of bubbles can be suppressed. The same is because the peripheral area A1 and the central area A2 are smaller than the coating area of the comparative example, so the resin component of the flux is easily and quickly discharged from the molten solder. This is the same as that of Example 1~ 5 same.

(Example 17)

The application area of the solder paste in Example 17 will be described with reference to Fig. 21. In addition, in the following description of Embodiment 17, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (six) peripheral areas A1 arranged at intervals G in the circumferential direction around the center O of the pad P, and a central area located at the radial inner side of the plurality of peripheral areas A1 Domain A2. Each of the peripheral area A1 and the central area A2 is a circle with a diameter of 0.3 mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 21.

The plural peripheral regions A1 are arranged at equal intervals in the circumferential direction. 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 regions A1 are arranged to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located outside the pad P in the radial direction. The plurality of peripheral regions A1 may also be a configuration in which all are arranged in the pad P.

The gap ratio GR of this example is calculated. The angle θ _C is between a straight line L1 extending from the center O to the radial outside and passing through the center of the peripheral area A1 on the upper right of the paper, and a straight line L2 extending from the center O to the radial outside and tangent to the upper right peripheral area A1 of the paper. The angle can be 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 this embodiment is (180°-6×θ _C )/180°=41.8%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×7)/(0.5 ² ×π)=63%.

The maximum bubble area ratio of this embodiment is 10.9%.

(Example 18)

The application area of the solder paste in Example 18 will be described with reference to Fig. 22. In the following description of Embodiment 18, only the configuration different from the foregoing Embodiment 17 will be described, and the description of other configurations will be omitted.

The central area A2 is a circle with a diameter of 0.4mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in Fig. 22.

The area of the central area A2 is 178% of the area of each peripheral area A1.

The gap ratio GR of this example is the same as that of Example 17, which is 41.8%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×6+0.2 ² ×π)/(0.5 ² ×π)=43.1%.

The maximum bubble area ratio of this embodiment is 4.6%.

(Example 19)

The application area of the solder paste in Example 19 will be described with reference to Fig. 23. In addition, in the following description of Embodiment 19, only the configuration different from the foregoing Embodiment 17 will be described, and the description of other configurations will be omitted.

The central area A2 is a circle with a diameter of 0.5mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 23.

The area of the central area A2 is 278% of the area of each peripheral area A1.

The gap ratio GR of this example is the same as that of Example 17, which is 41.8%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×6+0.25 ² ×π)/(0.5 ² ×π)=48.7%.

The maximum bubble area ratio of this embodiment is 12.4%.

(Example 20)

The application area of the solder paste in Example 20 will be described with reference to Fig. 24. In addition, in the following description of the embodiment 20, only the configuration different from the foregoing embodiment 17 will be described, and the description of the other configurations will be omitted.

The central area A2 is a circle with a diameter of 0.2mm. The central area A2 is arranged so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in Fig. 24.

The area of the central area A2 is 44.4% of the area of each peripheral area A1.

The gap ratio GR of this example is the same as that of Example 17, which is 41.8%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×6+0.1 ² ×π)/(0.5 ² ×π)=35.7%.

The maximum bubble area ratio of this embodiment is 17.8%.

(Example 21)

The application area of the solder paste in Example 21 will be described with reference to Fig. 25. In the following description of Embodiment 21, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (two) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a circle 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 so that its center coincides with the center O of the pad P in a plan view. The mutual positional relationship between the plurality of peripheral areas A1 and the central area A2 is shown in FIG. 25.

The plural peripheral regions A1 are arranged at equal intervals in the circumferential direction. The plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The gap ratio GR of this embodiment can be calculated with reference to the foregoing embodiment 17, and is (180°-2×θ _C )/180°=80.6%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×3)/(0.5 ² ×π)=27%.

The maximum bubble area ratio of this embodiment is 3.8%.

(Example 22)

The application area of the solder paste in Example 22 will be described with reference to Fig. 26. In addition, in the following description of Embodiment 22, only the configuration that is different from the foregoing Embodiment 6 will be described, and the description of other configurations will be omitted.

The coating area T has a plurality of (four) 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 on the radial inner side of the plurality of peripheral areas A1. Each of the peripheral area A1 and the central area A2 is a circle 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. 26.

The plural peripheral regions A1 are arranged at equal intervals in the circumferential direction. The plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The gap ratio GR of this embodiment can be calculated with reference to the foregoing embodiment 17, and is (180°-4×θ _C )/180°=61.2%.

The coating area ratio AR of this embodiment is (0.15 ² ×π×5)/(0.5 ² ×π)=45%.

The maximum bubble area ratio of this embodiment is 4.9%.

(Review of Examples 17-22)

The maximum bubble area ratio VR of Examples 17 to 22 is lower than that of Comparative Examples. From this, it can be seen that all of Examples 17 to 22 can suppress the size of bubbles generated in the solder paste.

The reason for suppressing the size of bubbles is discussed below. First, the peripheral area A1 and the central area A2 are both smaller than the coating area of the comparative example, so the resin component of the flux is easily and quickly discharged from the molten solder. This point is the same as in Examples 1 to 5.

In addition, although Examples 17 to 22 all have a central area A2, the solder powder applied in the solder paste in the central area A2 flows radially outward after melting. It can be understood that the central area of each of Examples 17 to 22 is opened from the center O toward the radial outside through the gap G, so the same is to calculate the plural number of openings from the center O of the pad P to the radial outside The ratio of the gap between the peripheral regions A1 to the entire circumference of the pad P is taken as the gap ratio GR. Therefore, the melt flowing from the central area The molten solder can flow tangentially outward in the radial direction through the gap G, so that the resin component of the flux can be discharged outward in the radial direction.

In Examples 17 to 22, the area of the central area A2 was 44.4% to 278% of the area of each peripheral area A1.

(Example 23)

The application area of the solder paste in Example 23 will be described with reference to Fig. 27.

In Embodiment 23, the non-coating area N is formed in the pad P on the substrate B, and the solder paste is applied to at least a part of the coating area T located in the pad P. The coating area T has a plurality of (two) peripheral areas A1 arranged at intervals G in the circumferential direction around the center O of the pad P. The two peripheral regions A1 are arranged such that a part of the radial inner side is in contact with each other. In this embodiment, the meeting point of the two peripheral areas A1 is located at the same position as the center O in a plan view. The shape of each peripheral area A1 is a right-angled isosceles triangle with a vertex located at the center O and a vertex angle of 90°. The length of the base (side opposite to the aforementioned vertex) of each peripheral area A1 is 1.0 mm. The distance between the bottom edges of the two peripheral areas A1 is also 1.0 mm. The width in the circumferential direction of each peripheral area A1 gradually increases from the center O of the pad P to the radially outer side.

The plurality of peripheral areas A1 are arranged at equal intervals in the circumferential direction. In addition, a plurality of peripheral regions A1 may not be arranged at equal intervals in the circumferential direction.

The plurality of peripheral regions A1 are arranged to overlap the outer edge of the pad P. That is, a part of each peripheral area A1 is located outside the pad P in the radial direction. In addition, the plurality of peripheral areas A1 may also be configured to be all arranged in the pad P.

The gap ratio GR of this embodiment is 50%.

The coating area ratio AR of this embodiment is (1.0 ² /2)/(0.5 ² ×π)=63.7%.

The maximum bubble area ratio of this embodiment is 12.5%.

(Example 24)

The application area of the solder paste in Example 24 will be described with reference to Fig. 28. In the following description of the embodiment 24, in addition, only the configuration different from the foregoing embodiment 23 will be described, and the description of the other configurations will be omitted.

The length of the bottom side of each peripheral area A1 is 1.3 mm. The distance between the bottom edges of the two peripheral areas A1 is also 1.3 mm.

The coating area ratio AR of this embodiment is (1.3 ² /2)/(0.5 ² ×π)=107.6%.

The maximum bubble area ratio of this embodiment is 14.6%.

(Review of Examples 23 and 24)

The maximum bubble area ratio VR of Examples 23 and 24 is lower than that of Comparative Example. From this, it can be seen that both Examples 23 and 24 can suppress the size of bubbles generated in the solder paste.

The reason for suppressing the size of bubbles is discussed below. First, the peripheral area A1 and the central area A2 are both smaller than the coating area of the comparative example, so the resin component of the flux is easily and quickly discharged from the molten solder. This point is the same as in Examples 1 to 5.

In addition, although Examples 23 and 24 do not have a central area, the radially inner portion of the peripheral area A1 reaches the central portion of the pad P. Therefore, the solder powder in the solder paste applied to the radially inner portion of the peripheral area A1 may flow toward the radially outer side in the left-right direction of the paper after being melted. In each of Examples 23 and 24, the radially inner portion of the peripheral area A1 is also open from the center O toward the radially outer side through the gap G, so the gap ratio GR is calculated in the same way. Therefore, the molten solder in the radially inner portion of the peripheral area A1 can flow appropriately to the radially outer side through the gap G, so that the resin component of the flux can be discharged to the radially outer side.

(Modifications of Examples 23 and 24)

Examples 23 and 24 can consider the following modifications.

In the two embodiments, two peripheral areas A1 are provided, but the number of peripheral areas A1 can be more than three. In this case, it is possible to reduce the ratio at which the circumferential width of each peripheral area A1 expands toward the radially outer side. In addition, the contact point of the two peripheral regions A1 may be arranged at a position different from the center O of the pad P in a plan view.

(Example 25)

The application area of the solder paste in Example 25 will be described with reference to Fig. 29.

In Embodiment 25, a non-coating area N is formed in the solder pad P on the substrate B, and the solder paste is applied to at least a part of the coating area T located in the solder pad P. The coating area T has an extension area A3 that includes the center O of the pad P and extends in a single direction (in this embodiment, in the left-right direction of the paper). The extension area A3 has a rectangular shape as seen from a plan view, the length in the long side direction is 1.3 mm, and the width in the short side direction is 0.3 mm.

The extension area A3 is arranged to overlap the outer edge of the pad P. That is, a part of the extension area A3 is located on the radially outer side of the pad P. In this embodiment, both ends of the extension area A3 in the longitudinal direction are located outside the pad P in the radial direction. The extension area A3 can also be all arranged in the pad P, or only one end of the extension area A3 in the longitudinal direction is outside the pad P in the radial direction.

In this embodiment, since the extension area A3 extends to the radially outer side of the pad P, the gap ratio GR cannot be calculated.

The coating area ratio AR of this embodiment is (1.3×0.3)/(0.5 ² ×π)=49.7%.

The maximum bubble area ratio of this embodiment is 17.5%.

(Example 26)

The application area of the solder paste in Example 26 will be described with reference to Fig. 30. In the following description of the 26th embodiment, only the configuration that is different from the foregoing embodiment 25 will be described, and the description of the other configurations will be omitted.

The coating area T further has a plurality of (two) side areas A4 arranged with the extending area A3 interposed therebetween in a direction intersecting the longitudinal direction of the extending area A3. The shape of each side area A4 as seen from a plan view is a square with a side length of 0.3 mm, and one side extends in the vertical direction on the paper. The mutual positional relationship between the plurality of side areas A4 and the extension area A3 is shown in FIG. 30.

The opposite sides a and b of the extended area A3 and the side areas A4 are parallel to each other. The opposite sides a and b may not be parallel to each other.

The plurality of side areas A4 are arranged to overlap the outer edge of the pad P. That is, a part of each side area A4 is located outside the pad P in the radial direction. The plurality of side areas A4 may also be a configuration in which all are arranged in the pad P.

The coating area ratio AR of this embodiment is (1.3×0.3+0.3 ² ×2)/(0.5 ² ×π)=72.6%.

The maximum bubble area ratio of this example is 15.0%.

(Review of Examples 25 and 26)

The maximum bubble area ratio VR of Examples 25 and 26 is lower than that of Comparative Example. From this, it can be seen that both Examples 25 and 26 can suppress the size of bubbles generated in the solder paste.

Discuss the reason why the size of the bubbles can be suppressed. The same is because the extended area A3 and the side area A4 are smaller than the coating area of the comparative example, so the resin component of the flux is easily and quickly discharged from the molten solder. This is the same as Example 1. ~5 Same.

(Modifications of Examples 25 and 26)

In Examples 25 and 26, the following modifications can be considered.

For example, the number of the plurality of side areas A4 may be three or more.

The gap ratio GR, the coating area ratio AR, and the maximum bubble area ratio VR of the foregoing Examples 1 to 26 are summarized and shown in Table 1.

[Table 1]

The maximum bubble area ratio VR of Examples 1 to 26 is lower than that of Comparative Examples. From this, it can be seen that all the examples can suppress the size of bubbles generated in the solder paste. Therefore, it is possible to provide: a suitable electrical connection between the coated object such as a substrate and the electrodes on both sides of the electronic component, and the impact resistance of the surface mount substrate can be prevented because the strength of the solder connecting the two electrodes can be prevented Wait.

As mentioned above, an embodiment of the present invention has been described. However, the present invention is not limited to the foregoing embodiment, but can be modified without departing from the spirit of the present invention.

For example, in the foregoing embodiment, although the shape of the pad P on the substrate B as the coating target object is circular in plan view, it is not limited to this, and may be rectangular or polygonal, for example.

In the foregoing embodiment, although a printed circuit board composed of a hard plate-shaped base material is used as an object to be coated, a flexible substrate may be used as an object to be coated with solder paste. In addition, when directly connecting another electronic component to one electronic component, the aforementioned one electronic component can be regarded as an object to be coated and the solder paste can be applied to the electrode surface. The object to be coated may be any member as long as it can be coated with solder paste.

In the foregoing embodiment, when the solder paste is applied to the coating object, screen printing using a mask M is used. However, it is also possible to directly use a discharge nozzle that can move on the substrate without using a mask or the like. The dispenser applies solder paste to the coating area as shown in the foregoing Examples 1 to 26.

The present invention may also include the following aspects.

The fourth aspect of the present invention is a mask for applying solder paste to an object to be coated, which is located in a bonding area with at least a part of the object to be coated so that non-coating is formed in the bonding area. An opening is formed at a position corresponding to the coating area of the area, and the opening has a plurality of peripheral openings arranged at intervals in the circumferential direction around the center of the bonding area.

The fifth aspect of the present invention is a mask for applying solder paste to an object to be coated, which is in a bonding area with at least a part of the object to be coated so that non-coating is formed in the bonding area. An opening is formed at a position corresponding to the coating region of the region, and the opening has an extension opening that includes the center of the bonding region and extends in a single direction.

[Industrial availability]

The present invention can be applied to a method of applying solder paste to a coated object such as a printed circuit board, and a mask used for the coating, and can suppress the bubbles even when bubbles are formed in the solder during surface mounting the size of.

A1‧‧‧ Surrounding area

a,b‧‧‧the opposite side

B‧‧‧Substrate (coating object)

G‧‧‧Interval

L1,L2,L3‧‧‧Straight

N‧‧‧Non-coated area

O‧‧‧ Center

P‧‧‧Pad (joining area)

T‧‧‧coating area

Claims (25)

A solder paste coating method is a coating method for applying solder paste to a coating object, including: A procedure of applying solder paste to the coating area in such a way that a non-coating area is formed in the joining area of the coating object, wherein at least a part of the coating area is located in the aforementioned joining area, The coating area has a plurality of peripheral areas arranged at intervals in a circumferential direction surrounding the center of the bonding area. The solder paste coating method as described in item 1 of the scope of patent application, wherein: The plurality of peripheral regions are arranged opposite to each other with the center of the bonding region interposed therebetween. The solder paste coating method as described in item 2 of the scope of patent application, wherein: The plurality of peripheral regions are arranged to extend in a direction crossing the opposing direction of the plurality of peripheral regions. Such as the solder paste coating method described in item 2 or 3 of the scope of patent application, wherein: The gap between the plurality of peripheral regions is 30% or more and 70% or less of the maximum diameter of the bonding region. The solder paste coating method as described in any one of items 2 to 4 of the scope of patent application, wherein: The gap between the plurality of peripheral regions is 85.7% or more and 200% or less of the width of each peripheral region in the opposing direction of the plurality of peripheral regions. The solder paste coating method as described in item 1 of the scope of patent application, wherein: The number of the aforementioned plural peripheral regions is 2 to 6. Such as the solder paste coating method described in item 1 or 6 of the scope of patent application, wherein: The plurality of peripheral regions are arranged at equal intervals in the circumferential direction. Such as the solder paste coating method described in item 1, 6 or 7 of the scope of patent application, wherein: The plurality of peripheral regions have first and second regions with different lengths in the circumferential direction, The first area and the second area are alternately arranged in the circumferential direction. The solder paste coating method as described in any one of items 1 to 8 of the scope of patent application, wherein: The opposing sides of the plurality of peripheral regions adjacent in the circumferential direction are parallel to each other. The solder paste coating method as described in any one of items 1 to 9 of the scope of patent application, wherein: The coating area further has a central area located at the radial inner side of the plurality of peripheral areas. The solder paste coating method described in item 10 of the scope of patent application, wherein: The opposite sides of the aforementioned central area and each peripheral area are parallel to each other. The solder paste coating method described in item 10 or 11 of the scope of patent application, wherein: The area of the aforementioned central area is 44.4% to 278% of the area of each peripheral area. The solder paste coating method as described in item 1 of the scope of patent application, wherein: The plurality of peripheral regions are partially connected and arranged. The solder paste coating method as described in item 13 of the scope of patent application, wherein: The width in the circumferential direction of each peripheral region gradually increases from the center of the joining region toward the radially outer side. The solder paste coating method as described in any one of items 1 to 14 of the scope of patent application, wherein: The ratio of the gaps between the plurality of peripheral regions that open from the center of the bonding region toward the radially outer side relative to the entire circumference of the bonding region is 11.5% or more. The solder paste coating method as described in any one of items 1 to 15 in the scope of patent application, wherein: The plurality of peripheral regions are arranged to overlap the outer edges of the bonding region. The solder paste coating method as described in any one of items 1 to 15 in the scope of patent application, wherein: The plurality of peripheral regions are arranged in the joint region. A solder paste coating method is a coating method for applying solder paste to a coating object, including: A procedure of applying solder paste to the coating area in such a way that a non-coating area is formed in the joining area of the coating object, wherein at least a part of the coating area is located in the aforementioned joining area The coating area has an extension area that includes the center of the bonding area and extends in a single direction. The solder paste coating method as described in item 18 of the scope of patent application, wherein: The extension area is arranged to overlap the outer edge of the joining area. The solder paste coating method as described in item 18 of the scope of patent application, wherein: The extension area is arranged in the joining area. The solder paste coating method described in any one of items 18 to 20 of the scope of patent application, wherein: The coating area further has a plurality of side areas arranged with the extending area interposed in a direction crossing the longitudinal direction of the extending area. The solder paste coating method as described in item 21 of the scope of patent application, wherein: The opposite sides of the aforementioned extended area and each side area are parallel to each other. The solder paste coating method as described in item 21 or 22 of the scope of patent application, wherein: The plurality of side regions are arranged to overlap the outer edges of the joint region. The solder paste coating method as described in item 21 or 22 of the scope of patent application, wherein: The plurality of side regions are arranged in the joint region. A mask used in the solder paste coating method described in any one of the scope of the patent application from 1 to 24, and an opening is formed at a position corresponding to the aforementioned coating area.

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