JP2001085832A - Method and device for manufacturing electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting structure where stresses at expansion/contraction is relaxed, to suppress crackings for improved soldering junctions. SOLUTION: Each pair of multiple lands 2, provided on a mounting surface 1A of a printed wiring board 1 and multiple electrodes 15 of a BGA(ball grid array) 12 are connected with a bump 14. Here, a land-forming surface 2A provided at the mounting surface 1A is divided into a plurality of land formation surface sections 20, 21, and 22, among which steps are provided so to be deeper the closer it is to the outside, with lands 2-1, 2-2, and 2-3 provided at the land formation surface parts 20, 21, and 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic components such as chip components, ICs, packages with leads,
The present invention relates to a mounting structure such as a GA (ball grid array) and a mounting method thereof.

[0002]

2. Description of the Related Art Conventionally, electronic parts (chip parts, ICs, etc.)
In the surface mounting method, solder paste is printed on a printed wiring board using a screen mask, components are mounted (mounted), and soldering is performed.

That is, as shown in FIG.
A land 32 is formed on the mounting surface 31A of the printed wiring board 31. Then, as shown in FIG. 24 (2), in the printing step, a screen mask 34 is arranged on the mounting surface 31A of the printed wiring board 31, and the screen mask 34
By supplying the solder paste 35 on the top and pushing and moving the solder paste 35 with a squeegee 36,
Solder paste 35 is applied to land 3 from mask opening 34A.
Feed to 2.

[0006] Next, as shown in FIG. 24 (3), the chip component 36 is mounted (mounted) on the mounting surface 31 A in a mounting step, and thereafter, in a reflow step as shown in FIG. 24 (4). Then, the chip component 36 is soldered by heating (reflow).

[0005] With the miniaturization of electronic components, the electrodes of these electronic components have become smaller and smaller. For this reason, the lands 32 and the mask openings 34A are also miniaturized.
In order to secure and improve the reliability of soldering, it is important to increase the amount of solder supplied.

[0006]

However, according to the above-described conventional mounting method, the lands 32 and the mask openings 34A are miniaturized, so that the lands 32 and the mask openings 34A are aligned with the electrodes of the electronic component. If the solder paste 35 is too small, the solder paste 35 cannot be supplied sufficiently. Therefore, there is a problem that it is difficult to secure and improve the reliability. The ratio (mask thickness / mask opening width) becomes large, and there is a problem that it is difficult to print the solder paste 35 according to the mask opening dimensions.

Further, if the mask opening 34A is widened in the width direction in order to increase the amount of solder supplied, there is a problem that a bridge defect in which leads are connected by solder at the time of melting the solder is likely to occur because the electrode terminals are narrow. Was.

In general, a BGA (ball grid array) 37 is used for surface mounting of an LSI in which solder balls 38 are arranged in a grid on electrodes 39 provided on a package body 40 as shown in FIGS. It is an area array type package. In the case of the BGA 37, the electrodes 39 are within the size range of the package, the electrodes 39 are arranged at the same size and at the same pitch, and the electrodes 39 are provided with solder balls 37 of the same size.

In a method of mounting a BGA (Ball Grid Array) 37 as an electronic mounting component,
As shown in FIG. 25A, in the printing process, a screen mask 34 is arranged on the mounting surface 31A of the printed wiring board 31, and the solder paste 3 is placed on the screen mask 34.
The solder paste 35 is supplied to the land 32 through the mask opening 34A by pushing and moving the solder paste 35 with a squeegee 36.

Next, as shown in FIG. 25 (3), the solder balls 38 of the BGA 37 are
2 and is mounted (mounted) on the mounting surface 31A while being in contact with the solder paste 35 supplied to the substrate 2, and then (4) in FIG.
The BGA 37 is soldered by heating (reflow) in the reflow step as shown in FIG.

In order to increase the solder supply amount by the above-described conventional mounting method and increase the height H7 of the bump 41 shown in FIG. 31, the size of the land 32 and the size of the mask opening 34A of the screen mask 34 are increased. There are two methods of increasing only the size of the mask opening 34A of the screen mask 34. However, since the terminal pitch is narrow, the solder paste 35 for increasing the size of the land 32 and the size of the mask opening 34A is used. There was a problem that they contacted each other.

The mounting surface 31A of the printed wiring board 31
The BGA 37 mounted on the device repeats expansion and contraction due to a temperature change due to an outside air temperature or heat generation. At this time, since the thermal expansion coefficients of the printed wiring board 31 and the BGA 37 are different, a difference occurs in the amount of expansion and contraction displacement at the joint. The displacement amount is large on the inside and outside of the BGA 37.
The stress F of the expansion / contraction applied to the bump 41 shown in FIG.

It is known that the higher the bump 41, the better the bonding reliability because it absorbs the difference in the displacement amount. However, in the current BGA 37, the bumps 41 are all the same size regardless of the stress F. In addition, there is a problem that the difference in the displacement amount cannot be completely absorbed by the outer bumps 41, and cracks are easily generated in the corner portions 42 as shown in FIGS.

The present invention has been made in view of the above problems, and a first object of the present invention is to increase the amount of supplied solder and increase the thickness of the solder under the electronic mounting component. Accordingly, an object of the present invention is to provide an electronic component mounting structure in which the reliability of a soldered joint is improved.

A second object of the present invention is to reduce the stress at the time of expansion and contraction, suppress the occurrence of cracks, and improve the reliability of the soldered joint. It is to provide a component mounting structure.

A third object of the present invention is to provide an electronic component mounting method for improving the reliability of a soldered joint.

[0017]

According to a first aspect of the present invention, there is provided an electronic component mounting structure according to the first aspect of the present invention, wherein a land provided on a mounting surface of a printed wiring board has a concave shape. The terminals are brought into contact with the solder paste supplied to the lands to mount the electronic components, and the electronic components are soldered to the printed wiring board by reflow.

With this configuration, since the land has a concave shape, the amount of supplied solder increases, the thickness of the solder under the electronic mounting component increases, and the reliability of the soldered joint can be improved.

According to a second aspect of the present invention, there is provided an electronic component mounting structure according to the first aspect, wherein the electronic component is a chip component. The terminal side of the chip component is soldered with the solder paste supplied to the land.

With this configuration, since the land has a concave shape, the amount of supplied solder increases, the thickness of the solder under the chip component increases, and the reliability of the soldered joint can be improved.

According to a third aspect of the present invention, there is provided an electronic component mounting structure according to the first aspect, wherein the electronic component is a package having leads. The leads of the package component are soldered by the solder paste supplied to the land.

With this configuration, since the land has a concave shape, the supply amount of solder increases, the back fillet can be increased, and the reliability of the solder joint can be improved. Also, even when the solder is melted, there is no flow to the adjacent lead, so that a bridge failure does not occur.

According to a fourth aspect of the present invention, there is provided an electronic component mounting structure according to the first aspect, wherein the electronic component is mounted on the electrode side. This is a semiconductor package in which solder balls are arranged, and the solder balls are soldered by solder paste supplied to the lands.

According to this configuration, since the land has a concave shape, the amount of supplied solder is increased, and the height of the bump at the time of joining can be increased. Also, the amount of solder to be supplied can improve the reliability of the soldered joint by controlling the depth of the concave portion of the land,
Also, by increasing the width of the land to the same width as the diameter of the solder ball, the reliability of the soldered joint can be improved.

According to a fifth aspect of the present invention, there is provided an electronic component mounting structure comprising a semiconductor package in which a solder ball is arranged on an electrode side, and a printed wiring. The land provided on the mounting surface of the plate was formed in a concave shape, and solder balls were inserted directly into the land and soldered.

With this configuration, a screen mask is not required, and defects due to the printing process can be prevented.

According to another aspect of the present invention, there is provided an electronic component mounting structure according to the present invention, wherein each of the lands provided on the mounting surface of the printed wiring board and the plurality of electrodes of the semiconductor package is provided. Is an electronic component mounting structure in which opposing pairs are connected by bumps, and the diameter and height are increased as the number of bumps is increased.

With such a configuration, since the diameter and the height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be alleviated, the generation of cracks can be suppressed, and the solder joint can be suppressed. Can be improved in reliability.

According to another aspect of the present invention, there is provided an electronic component mounting structure according to the present invention, comprising a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package. Electronic component mounting structure in which each pair is connected by a bump, the land forming surface provided on the mounting surface is divided into a plurality of land forming surface portions, and the outer one of these land forming surface portions becomes deeper. With a step,
The lands were arranged on the land forming surface.

According to this configuration, since the diameter and height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be relaxed, cracks can be suppressed, and the solder joints can be suppressed. Can be improved in reliability.

In order to achieve the first object, the electronic component mounting structure according to the invention of claim 8 is the electronic component mounting structure according to claim 7, wherein , Increased its diameter.

With such a configuration, since the diameter and the height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be alleviated, the generation of cracks can be suppressed, and the solder joints can be reduced. Can be improved in reliability.

In order to achieve the above-mentioned second object, an electronic component mounting structure according to a ninth aspect of the present invention provides a semiconductor device comprising: a plurality of lands provided on a mounting surface of a printed wiring board; The mounting structure of an electronic mounting component in which each pair is connected by a bump, the larger the outside of a large number of lands, the larger the diameter and the height of the electrode forming surface of the semiconductor package from the center to the outer peripheral portion. A large number of electrodes are arranged on the electrode forming surface, and the outer diameter of these electrodes is larger.

According to this structure, since the diameter and the height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be alleviated, and the occurrence of cracks can be suppressed. Can be improved in reliability.

In order to achieve the second object, the electronic component mounting structure according to the tenth aspect of the present invention includes a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package. Electronic component mounting structure in which each pair is connected by a bump, the larger the outside of a large number of lands, the larger the diameter is, and the electrode forming surface of the semiconductor package is divided into a plurality of electrode forming surface portions. Steps are provided so that the outer side of the electrode forming surface of
The electrodes are arranged on the electrode forming surface portion, and the diameters of the electrodes outside the electrodes are increased as they are located.

With this configuration, since the diameter and height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be reduced, cracks can be suppressed, and the solder joints can be reduced. Can be improved in reliability.

In order to achieve the above-mentioned second object, an electronic component mounting structure according to the present invention is characterized in that a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are provided. Electronic component mounting structure in which each pair is connected by a bump, the larger the outside of a large number of lands, the larger the diameter is, and the electrode forming surface of the semiconductor package is divided into a plurality of electrode forming surface portions. Steps are provided so that the outer side of the electrode forming surface of
The electrodes were arranged on the electrode forming surface, and all the electrodes were the same size.

With such a configuration, since the diameter and height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be alleviated, the generation of cracks can be suppressed, and the solder joints can be reduced. Can be improved in reliability.

According to another aspect of the present invention, there is provided an electronic component mounting structure comprising: a plurality of lands provided on a mounting surface of a printed wiring board; and a plurality of electrodes of a semiconductor package. Is an electronic component mounting structure in which each pair is connected by a bump, and the electrodes are enlarged with respect to the lands, and the bumps are shaped so that the land joining surface is larger and conical in width than the electrode joining surface. It was done.

With this configuration, stress during expansion and contraction can be reduced, cracks can be suppressed, and the reliability of the soldered joint can be improved.

According to a third aspect of the present invention, there is provided an electronic component mounting method according to the third aspect, wherein the land provided on the mounting surface of the printed wiring board is formed in a concave shape.
A solder paste is supplied to a land in a printing process, an electronic mounting component is mounted by bringing a terminal side into contact with the solder paste in a mounting process, and the electronic mounting component is soldered by reflow in a reflow process.

Therefore, since the land has a concave shape, the amount of supplied solder increases, the thickness of the solder under the electronic mounting component increases, and the reliability of the soldered joint can be improved.

According to a third aspect of the present invention, there is provided a method of mounting an electronic component, wherein the electronic component is a semiconductor package in which solder balls are arranged on an electrode side. The land provided on the mounting surface was formed into a concave shape, the solder balls were directly inserted into the lands in a mounting step, and the electronic mounting parts were soldered by reflow in a reflow step.

Therefore, a screen mask is not required, and defects due to the printing process can be prevented.

According to a third aspect of the present invention, there is provided an electronic component mounting method, comprising: supplying a solder paste to a land provided on a mounting surface of a printed wiring board in a printing step; An electronic component mounting method in which an electronic mounting component is mounted by bringing a terminal side into contact with a solder paste in a mounting process, and an electronic mounting component is soldered by reflow in a reflow process. A semiconductor package with solder balls,
The land formation surface provided on the mounting surface is divided into a plurality of land formation surfaces, steps are provided so that the outer sides of these land formation surfaces become deeper, lands are arranged on the land formation surface, and used in the printing process Using a thick mask as the screen mask to be formed, the solder paste was supplied to the lands from the mask openings of the screen mask, so that the amount of the solder supplied to the outer lands became larger.

Therefore, the larger the outside of the bumps, the larger their diameter and height, so that the stress at the time of expansion and contraction can be reduced, and the occurrence of cracks can be suppressed.
The reliability of the solder joint can be improved.

According to a third aspect of the present invention, there is provided an electronic component mounting method, comprising: supplying a solder paste to a land provided on a mounting surface of a printed wiring board in a printing step; An electronic component mounting method in which the terminals are brought into contact with a solder paste in a mounting process to mount the electronic components, and in a reflow process, the electronic components are soldered by reflow. A semiconductor package with solder balls,
The land formation surface provided on the mounting surface is divided into a plurality of land formation surfaces, steps are provided so that the outer sides of these land formation surfaces become deeper, lands are arranged on the land formation surface, and used in the printing process As the screen mask to be used, a screen mask whose diameter becomes larger as the outer mask opening is used, and the solder paste is supplied from the mask opening to the land so that the amount of solder supplied to the outer land becomes larger.

Therefore, since the diameter and height of the bumps outside the large number of bumps increase, the stress at the time of expansion and contraction can be reduced, and the occurrence of cracks can be suppressed.
The reliability of the solder joint can be improved.

[0049]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) (1) to (1) of FIG.
(4) shows a first embodiment of the present invention. The electronic component in the first embodiment is a chip component.

In the first embodiment of the present invention, the land 2 provided on the mounting surface 1A of the printed wiring board 1 is formed in a concave shape, and the terminal side is brought into contact with the solder paste 5 supplied to the land 2. The chip component 7 as an electronic mounting component is mounted, and the chip component 7 is mounted on the printed wiring board 1 by reflow.
Is to be soldered.

That is, as shown in FIG. 1A, lands 2 are formed on the mounting surface 1A of the printed wiring board 1, and these lands 2 are formed in a concave shape. The depth H1 of these concave lands 2 is determined by deriving the required amount of solder from the fillet height H2 required when the fillet 8 is formed. A Cu pattern 3 is formed on the bottom surface of the land 2 having the concave shape, and the stability of the shape of the fillet 8 is secured.

Then, as shown in FIG. 1B, in the printing step, the screen mask 4 is arranged on the mounting surface 1A of the printed wiring board 1. In this case, the mask opening 4A of the screen mask 4 is positioned directly above the land 2 having the concave shape.

Then, the solder paste 5 is supplied onto the screen mask 4, and the solder paste 5 is pushed and moved by the squeegee 6, so that the solder paste 5 is supplied from the mask opening 4A to the land 2 having a concave shape. In this case, since the land 2 is not a flat surface but a concave portion, the amount of supplied solder increases.

Next, as shown in FIG. 1C, the chip component 7 is mounted (mounted) on the mounting surface 1A in a mounting step, and thereafter, in a reflow step as shown in FIG. Then, the chip component 7 is soldered by heating (reflow).

In the above-described first embodiment of the present invention, since the land 2 is processed into a concave shape, the amount of supplied solder increases, and the thickness of the solder under the chip component 7 increases. And the reliability of the soldered joint is improved.

(Second Embodiment) FIGS.
(5) shows a second embodiment of the present invention. The electronic component according to the second embodiment is a package component with leads.

The mounting structure of the electronic mounting component according to the present invention (second embodiment) is such that the land 2 provided on the mounting surface 1A of the printed wiring board 1 is formed into a concave shape and the solder paste supplied to the land is formed. The package component 10 is mounted by contacting the leads 10A, and the package component 10 is reflowed.
Are soldered.

That is, as shown in FIG. 2A, lands 2 are formed on the mounting surface 1A of the printed wiring board 1, and these lands 2 are formed in a concave shape. And
A Cu pattern 3 is provided on the bottom surface of the concave land 2 to ensure the stability of the fillet shape.

In this case, the mounting surface 1A of the printed wiring board 1
The maximum depth H3 of the recessed land 2 formed in the above is the length from the lowermost end of the lead 10A to the lower end of the package component 10.

Then, as shown in FIG. 2 (2), in the printing step, the screen mask 4 is arranged on the mounting surface 1 A of the printed wiring board 1. In this case, the mask opening 4A of the screen mask 4 is positioned directly above the land 2 having the concave shape. Then, the solder paste 5 is supplied onto the screen mask 4, and the solder paste 5 is pushed and moved by the squeegee 6, thereby supplying the solder paste 5 from the mask opening 4A to the land 2 having a concave shape. In this case, since the land 2 is not a flat surface but a concave portion, the amount of supplied solder increases.

Next, as shown in FIG. 2C, in a mounting step, the package component 10 with leads is mounted by bringing the leads 10A into contact with the solder paste 5 supplied to the lands 2 having the concave shape. Mounted on surface 1A (mount)
Then, as shown in (4) and (5) of FIG. 2, by heating (reflow) in a reflow step, the leads 10A of the package component 10 are soldered.

In the above-described second embodiment of the present invention, since the land 2 is processed into a concave shape, the amount of supplied solder is increased, and the back fillet 11 can be raised. The reliability of the solder joint can be improved. Further, since the land 2 is processed into a concave shape, no bridging defect occurs because there is no outflow to the adjacent lead 10A even when the solder is melted.

(Third Embodiment) FIGS.
(4) shows a third embodiment. The electronic mounting component according to the third embodiment is a semiconductor package, that is, a BGA (ball grid array) (a surface mounting area array type package of an LSI in which solder balls 13 are arranged in a lattice on the lower surface). It is.

As shown in FIG. 3A, lands 2 are formed on the mounting surface 1A of the printed wiring board 1, and the lands 2 are formed in a concave shape. A Cu pattern 3 is provided on the bottom surface of the land 2 having the concave shape to secure the stability of the fillet shape.

Then, as shown in FIG. 3B, in the printing step, the screen mask 4 is arranged on the mounting surface 1A of the printed wiring board 1. In this case, the mask opening 4A of the screen mask 4 is positioned directly above the land 2 having the concave shape. Then, the solder paste 5 is supplied onto the screen mask 4, and the solder paste 5 is pushed and moved by the squeegee 6, thereby supplying the solder paste 5 from the mask opening 4A to the land 2 having a concave shape. In this case, since the land 2 is not a flat surface but a concave portion, the amount of supplied solder increases.

Next, as shown in FIG. 3C, in a mounting step, the solder balls 13 of the BGA 12 are brought into contact with the solder paste 5 supplied to the concave lands 2 and mounted on the mounting surface 1A. ) And then (4) in FIG.
As shown in (1), the BGA 12 is soldered by heating (reflow) in the reflow step.

In the third embodiment of the present invention, since the land 2 is processed into a concave shape, the amount of supplied solder increases, and the height H4 of the bump 14 at the time of bonding increases.
Can be higher. The amount of solder to be supplied is land 2
Is controlled by the depth H1 of the concave portion. Thereby, the reliability of the soldered joint can be improved. In addition, by increasing the width of the land 2 to the same width as the diameter of the solder ball 13, the reliability of the solder joint can be further improved.

(Fourth Embodiment) FIG.
(3) shows a fourth embodiment of the present invention. The electronic mounting component according to the fourth embodiment is a BGA 12 in which solder balls 13 are arranged on the electrode side.
Is directly inserted into the land 2 and soldered.

That is, as shown in FIG. 4A, lands 2 are formed on the mounting surface 1A of the printed wiring board 1, and these lands 2 are formed in a concave shape. The width of the land 2 is slightly larger than the diameter of the solder ball 13. A Cu pattern 3 is provided on the bottom surface of the land 2 having the concave shape to secure the stability of the fillet shape.

Then, without supplying the solder paste 5 to the concave land 2, as shown in FIG. 4 (2), the BGA 12 is fitted with the solder ball 13 to the concave land 2 in the mounting step. And mounted on the mounting surface 1A, and then heated (reflowed) in a reflow step as shown in FIG.
Soldering.

In the above-described fourth embodiment of the present invention, the screen mask 4 is not required, and defects caused by the printing process can be prevented.

(Fifth Embodiment) FIGS. 5 to 11 show a fifth embodiment of the present invention. The electronic mounting component according to the fifth embodiment is a BGA (ball grid array) 12.

As shown in FIGS. 7 and 8, on the land forming surface 2A of the mounting surface 1A of the printed wiring board 1, inner, middle and outer land forming surfaces 20, 21 and 22 are formed concentrically. Yes, inner, middle and outer land forming surfaces 2
The heights h1, h2, and h3 of 0, 21, and 22 are stepped so as to be lower (deeper) in this order.

A large number of lands are formed on each of the inner, middle and outer land forming surfaces 20, 21 and 22. That is, the land 2-1 is located on the inner land forming surface portion 20, the land 2-2 is located on the intermediate land forming surface portion 21, and the land 2-3 is located on the outer land forming surface portion 22.
Are arranged, and the diameter of the middle land 2-2 is larger than the diameter of the inner land 2-1 and the diameter of the outer land 2-3 is larger than the diameter of the middle land 2-2.

As shown in FIGS. 9 and 10, a thick mask is used for the screen mask 4. That is, inside, middle and outside mask opening forming portions 23, 24 and 25 are formed on the back surface of the screen mask 4, and inside, middle and outside mask opening forming portions 2 are formed.
The heights f1, f2, f3 of 3, 24, 25 are stepped so as to be lower in this order.

The inner, middle, and outer mask opening forming portions 23, 24, and 25 have a large number of mask openings 4A.
Are formed, and the diameters of the mask openings 4A are the same.

Then, as shown in FIGS. 11A and 11B, in the printing step, the screen mask 4 is arranged on the mounting surface 1A of the printed wiring board 1. In this case, the mask opening 4A of the screen mask 4 is located immediately above the land 2. In this case, the inner, middle, and outer mask opening forming portions 23, 24, 25 come into contact with the inner, middle, and outer land forming surface portions 20, 21, 22.

Then, the solder paste 5 is supplied onto the screen mask 4 and the solder paste 5 is supplied to the squeegee 6.
To move the solder paste 5 from each mask opening 4A to each land 2-1, 2-2, 2-.
Supply 3 In this case, the amount of the supplied solder increases as the outer lands 2-3 increase.

Next, as shown in FIG. 11C, in the mounting step, the solder balls 13 of the BGA 12 are
-1, 2-2, and 2-3 are mounted on the mounting surface 1A in contact with the solder paste 5 supplied thereto.
As shown in FIG. 11D, in the reflow step, the BGA 12 is soldered by heating (reflow). In this case, the diameter and height of the outer bumps 14 increase.

In the above-described fifth embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Sixth Embodiment) FIGS. 12 to 14 show a sixth embodiment of the present invention. In the sixth embodiment, the electronic mounting component is a BGA (ball grid grid).
Array 12).

In the sixth embodiment, the same printed wiring board 1 as used in the fifth embodiment is used as the printed wiring board 1.

As shown in FIG. 12, a screen mask having a uniform thickness as a whole is used for the screen mask 4. The screen mask 4 has a large number of inner, middle and outer mask openings 4A-1, 4A-2, 4A-3, respectively.
The diameter of the intermediate mask opening 4A-2 is larger than the diameter of A-1 and the diameter of the mask opening 4A-3 outside the diameter of the mask opening 4A-2 is larger than the diameter of the mask opening 4A-2.

Then, as shown in FIG. 13, in the printing step, the screen mask 4 is arranged on the mounting surface 1 A of the printed wiring board 1. In this case, the mask openings 4A (4A-1, 4A-2, 4A-3) of the screen mask 4 are positioned immediately above the lands 2-1 2-2, 2-3.

Then, the solder paste 5 is supplied onto the screen mask 4 and the solder paste 5 is supplied to the squeegee 6.
To move the solder paste 5 into each mask opening 4A (4A-1, 4A-2, 4A-3).
To each land 2-1, 2-2, 2-3. In this case, the opening area (diameter) of the outer mask opening 4A-3
Since the outer lands 2-3 are larger, the amount of supplied solder is larger.

Next, in the same manner as in the fifth embodiment, FIG.
As shown in 1 (3), BGA12
The solder ball 13 is mounted on the mounting surface 1A by contacting the solder paste 5 supplied to the lands 2-1, 2-2, 2-3, and then, as shown in FIG. BGA by heating (reflow)
12 is soldered. In this case, the outer bump 14
The larger the diameter and the higher the height.

In the above-described sixth embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Seventh Embodiment) FIGS. 15 and 16 show a seventh embodiment of the present invention. The electronic mounting component according to the seventh embodiment is a BGA (Ball Grid
Array 12).

Many lands are formed on the mounting surface 1A of the printed wiring board 1. That is, on the mounting surface 1A, the inner, first, second middle and outer lands 2-1 and 2-
2, 2-3, and 2-4 are formed in large numbers, and the first intermediate land 2-2 is formed from the diameter of the inner land 2-1.
Is larger than the diameter of the first intermediate land 2-2 by the diameter of the second intermediate land 2-3.
The diameter of each of the lands 2-4 outside the diameter of the lands 3 is made larger.

The electrode forming surface 12A of the BGA 12 is
It has a shape that becomes higher from the center to the outer periphery, and a plurality of electrodes 15 are radially arranged on the electrode forming surface 12A from the center to the outer periphery. That is, a large number of inner, first, second, and outer electrodes 15-1, 15-2, 15-3, and 15-4 are formed on the electrode forming surface 12A, respectively. The diameter of the first intermediate electrode 15-2 is smaller than the diameter of the first intermediate electrode 15-2, and the diameter of the second intermediate electrode 15-3 is smaller than the diameter of the first intermediate electrode 15-2. Electrode 1 outside diameter of -3
The diameters of 5-4 are respectively enlarged.

Then, the electrodes 15 (15-1, 15-2,
15-3 and 15-4) have solder balls 1 respectively.
3 (13-1, 13-2, 13-3, 13-4) are attached, and these solder balls 13 (13-1, 13
-2, 13-3, 13-4), the larger the outer diameter, the larger.

Then, the BGA 12 is connected to the solder balls 13 (13-1, 13-2, 13-3, 13-4) of the printed wiring board 1 by the lands 2-1 2-2, 2-3, 2-
4 by mounting (mounting) on the mounting surface 1A by contacting with the mounting surface 4 and then heating (reflowing) in a reflow process.
The BGA 12 is soldered. In this case, the diameter and height of the outer bumps 14 increase.

In the above-described seventh embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Eighth Embodiment) FIGS. 17 and 18 show an eighth embodiment of the present invention. The electronic mounting component in the eighth embodiment is a BGA (ball grid grid).
Array 12).

A large number of lands 2 are randomly formed on the mounting surface 1 A of the printed wiring board 1.
The larger the diameter (area) of the outer side, the larger.

The electrode forming surface 12A of the BGA 12 is
The shape is such that the height increases from the center to the outer periphery, and a plurality of electrodes 15 are randomly arranged on the electrode forming surface 12A from the center to the outer periphery. The diameters (areas) of these electrodes 15 are made larger as they are located outside.

The electrodes 15 are provided with solder balls 13 respectively.
The outside diameter is larger for the outer one.

Then, the BGA 12 is mounted (mounted) on the mounting surface 1A by bringing the solder balls 13 into contact with the lands 2 of the mounting surface 1A of the printed wiring board 1, and then heated (reflowed) in a reflow step. , BGA1
2, the diameter and the height of the outer bump 14 are larger.

In the above-described eighth embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Ninth Embodiment) FIGS. 19 and 20 show a ninth embodiment of the present invention. The electronic component in the ninth embodiment is a BGA (Ball Grid Array) 12.

A large number of lands are formed on the mounting surface 1A of the printed wiring board 1. That is, a large number of inner, middle and outer lands 2-1 2-2, 2-3 are formed on the mounting surface 1A, respectively. The diameter of the middle land 2-2
The diameters of the lands 2-3 on the outer side of the diameter of the lands 2-3 are made larger.

The electrode forming surface 12A of the BGA 11 is concentrically formed on the inner, middle and outer electrode forming surfaces 26,
27, 28 are formed (partitioned), and the heights n1, n2 of the inner, middle, and outer electrode forming surface portions 26, 27, 28,
n3 is provided with a step so as to be higher in this order.

A large number of electrodes 15 are formed on the inner, middle and outer electrode forming surfaces 26, 27 and 28, respectively. That is, the electrode 15-1 is disposed on the inner electrode forming surface portion 26, the electrode 15-2 is disposed on the intermediate electrode forming surface portion 27, and the electrode 15-3 is disposed on the outer electrode forming surface portion 28. The diameter of the middle electrode 15-2 is larger than the diameter of the first electrode 15-1, and the diameter of the outer electrode 15-3 is larger than the diameter of the middle electrode 15-2.

The electrodes 15-1, 15-2, 15-
Each of the solder balls 3 has a solder ball 13 attached thereto.

Then, the BGA 12 and the solder balls 13 are connected to the lands 2-1 on the mounting surface 1A of the printed wiring board 1,
The BGA 12 is soldered by being mounted (mounted) on the mounting surface 1A in contact with the 2-2 and 2-3 and then heated (reflow) in a reflow step. In this case, the diameter and height of the outer bumps 14 increase.

In the ninth embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Tenth Embodiment) FIGS. 21 and 22
Shows a tenth embodiment of the present invention. The electronic component according to the tenth embodiment is a BGA (Ball Grid Array) 12.

In the tenth embodiment of the present invention, the configuration different from that of the ninth embodiment of the present invention
The inner, middle and outer electrode forming surfaces 26, 2 of the GA 12
7, 28, a large number of electrodes 15-1, 15-2,
Where the diameters of 15-3 are all the same,
The other configuration is the same as that of the ninth embodiment, so the same reference numerals are given and the description is omitted.

In the tenth embodiment of the present invention, since the outer bump 14 has a larger diameter and height, the stress at the time of expansion and contraction is reduced, and the occurrence of cracks is suppressed. The bonding reliability can be improved.

(Eleventh Embodiment) FIG. 23 shows an eleventh embodiment of the present invention. The electronic component in the eleventh embodiment is a ball grid array (BGA) 12.

A large number of lands 2 are radially formed on the mounting surface 1A of the printed wiring board 1. The electrode forming surface 14 of the BGA 12 is a flat surface perpendicular to the axis of the BGA 12.
5 are arranged radially, and the areas of these electrodes 15 are all the same. The area (land diameter) of the land 2 is larger than the area of the electrode 15.

When the BGA 12 is soldered to the lands 2, the bumps 14 have a land-bonding surface 17 having a larger conical spread than the electrode-bonding surface 18.

In the eleventh embodiment of the present invention described above, the bump 14 has a land-bonding surface 17 which is larger than the electrode-bonding surface 18 and has a conical expansion, so that the bump 14 is inflated. Stress at the time of shrinkage can be reduced, cracks can be suppressed, and bonding reliability can be improved.

[0115]

As described above, according to the electronic component mounting structure according to the present invention, the land provided on the mounting surface of the printed wiring board is formed into a concave shape, and the solder paste supplied to the land is connected to the terminal side. And the electronic mounting parts are mounted, and the electronic mounting parts are soldered to the printed wiring board by reflow.
The thickness of the solder under the electronic mounting component is increased, and the reliability of the soldered joint can be improved.

If the electronic component is a chip component, the terminal side of the chip component is soldered with solder paste supplied to the land, so that the solder thickness under the chip component increases, and In addition, when the electronic mounting components are packaged components with leads, the leads of the packaged components are soldered with the solder paste supplied to the lands, but the amount of supplied solder increases. As a result, the back fillet can be raised, the reliability of the solder joint can be improved, and the bridge defect does not occur because there is no flow to the next lead even when solder is melted. Become.

When the electronic component is a semiconductor package having solder balls arranged on the electrode side, the solder balls are soldered with the solder paste supplied to the lands, but the lands are formed in a concave shape. To
The supply amount of solder increases, and the height of the bump at the time of joining can be increased. In addition, the amount of solder to be supplied can improve the reliability of the solder joint by controlling the depth of the concave portion of the land, and the width of the land can be set to the same width as the diameter of the solder ball. By expanding the solder joint, the reliability of the soldered joint can be improved.

Further, the electronic packaging component is a semiconductor package in which solder balls are arranged on the electrode side. By directly inserting the solder balls into the lands and soldering, a screen mask becomes unnecessary, resulting in a printing process. Failure can be prevented.

Further, according to the electronic component mounting structure according to the present invention, an electronic component mounting structure in which lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected to each other by bumps. However, by increasing the diameter and height of the bumps outside, the stress during expansion and contraction can be reduced, cracks can be suppressed, and the reliability of the soldered joint can be reduced. Can be improved.

Further, according to the electronic component mounting structure according to the present invention, the electronic component mounting structure in which each pair of a large number of lands provided on the mounting surface of the printed wiring board and a large number of electrodes of the semiconductor package is connected by bumps. The land forming surface provided on the mounting surface is divided into a plurality of land forming surface portions, steps are provided so as to be deeper as those outside the land forming surface portions, and lands are arranged on the land forming surface portions. The larger the outside of the bumps, the larger the diameter and height, so the stress during expansion and contraction can be reduced, cracks can be suppressed, and the reliability of the soldered joints is improved. Can be done.

Further, even if the outer diameter of a large number of lands is larger, the outer diameter of a large number of bumps is larger in diameter and height. , Can suppress the occurrence of cracks,
The reliability of the solder joint can be improved.

Further, the diameter of the outer side of a large number of lands is increased, and the electrode forming surface of the semiconductor package is
It is formed so as to be higher from the center to the outer periphery, and a large number of electrodes are arranged on the electrode forming surface. Since the diameter and height are increased, the stress at the time of expansion and contraction can be reduced, cracks can be suppressed, and the reliability of the soldered joint can be improved.

Further, the diameters of the lands outside the lands are increased, and the electrode forming surface of the semiconductor package is divided into a plurality of electrode forming surfaces. Steps are provided, and the electrodes are arranged on the electrode forming surface portion.
Its diameter may be increased. Further, all the electrodes may have the same size.

Further, according to the electronic component mounting structure according to the present invention, the electronic component mounting structure in which each pair of a large number of lands provided on the mounting surface of the printed wiring board and a large number of electrodes of the semiconductor package is connected by bumps. Therefore, by increasing the electrode with respect to the land, the bump is formed in a shape in which the land joint surface has a larger conical spread than the electrode joint surface, thereby relaxing the stress during expansion and contraction, The occurrence of cracks can be suppressed, and the reliability of the soldered joint can be improved.

Further, according to the electronic component mounting method of the present invention, the land provided on the mounting surface of the printed wiring board is formed into a concave shape, the solder paste is supplied to the land in the printing step, and the solder paste is formed in the mounting step. By mounting the electronic mounting parts by contacting the terminal side and soldering the electronic mounting parts by reflow in the reflow process, the solder supply amount increases, the solder thickness under the electronic mounting parts increases, The reliability of the solder joint can be improved.

Further, according to the electronic component mounting method of the present invention, the electronic mounted component is a semiconductor package in which solder balls are arranged on the electrode side, and the solder balls are inserted directly into the lands and soldered. A screen mask is not required, and defects due to the printing process can be prevented.

Further, according to the electronic component mounting method of the present invention, the solder paste is supplied to the lands provided on the mounting surface of the printed wiring board in the printing step, and the terminals are brought into contact with the solder paste in the mounting step. An electronic component mounting method in which a mounting component is mounted and an electronic mounting component is soldered by reflow in a reflow process.The electronic mounting component is a semiconductor package in which solder balls are arranged on an electrode side. The provided land forming surface is divided into a plurality of land forming surface portions, steps are provided so as to be deeper as those outside the land forming surface portions, lands are arranged on the land forming surface portions, and a screen used in a printing process is provided. Using a thick mask as a mask, solder paste is supplied to the lands from the mask openings of the screen mask, and the outer lands are soldered. By increasing the supply amount, the larger the outside of the bumps, the larger the diameter and height, so that the stress during expansion and contraction can be relaxed, and the occurrence of cracks can be suppressed, The reliability of the soldered joint can be improved.

According to the electronic component mounting method of the present invention, the solder paste is supplied to the land provided on the mounting surface of the printed wiring board in the printing step, and the terminals are brought into contact with the solder paste in the mounting step. An electronic component mounting method in which a mounting component is mounted and an electronic mounting component is soldered by reflow in a reflow process.The electronic mounting component is a semiconductor package in which solder balls are arranged on an electrode side. The provided land forming surface is divided into a plurality of land forming surface portions, steps are provided so as to be deeper as those outside the land forming surface portions, lands are arranged on the land forming surface portions, and a screen used in a printing process is provided. Use a screen mask that has a larger diameter as the outer mask opening becomes the mask, and apply solder paste to the land from the mask opening. Then, by increasing the amount of solder supplied to the outer lands, the diameter and height of the outer bumps of a large number of bumps are increased. Generation can be suppressed, and the reliability of the soldered joint can be improved.

[Brief description of the drawings]

FIGS. 1 (1) to 1 (4) are process explanatory diagrams of a first embodiment of an electronic component mounting method according to the present invention.

FIGS. 2 (1) to (5) are process explanatory diagrams of a second embodiment of the electronic component mounting method according to the present invention.

FIGS. 3 (1) to (4) are process explanatory views of a third embodiment of the electronic component mounting method according to the present invention.

FIGS. 4 (1) to (3) are process explanatory diagrams of a fourth embodiment of the electronic component mounting method according to the present invention.

FIG. 5 is a plan view of an electronic component mounting structure according to the present invention.

FIG. 6 is a sectional view taken along line AA of FIG.

FIG. 7 is a plan view of a land formation surface of a printed wiring board and a land arrangement state provided on the land formation surface in the electronic component mounting structure.

FIG. 8 is a sectional view taken along line BB of FIG. 7;

FIG. 9 is a plan view of a screen mask.

FIG. 10 is a sectional view taken along line CC of FIG. 9;

FIGS. 11 (1) to (4) are process explanatory diagrams of a fifth embodiment of the electronic component mounting method according to the present invention.

FIG. 12 is a plan view of a screen mask.

FIG. 13 shows a sixth embodiment of the electronic component mounting method according to the present invention.
It is an explanatory view of a printing process of an embodiment.

FIG. 14 is a sectional view of an electronic component mounting structure manufactured by the electronic component mounting method.

FIG. 15 is an explanatory diagram of a bump arrangement in an electronic component mounting structure (seventh embodiment) according to the present invention.

FIG. 16 is a sectional view of the electronic component mounting structure (seventh embodiment).

FIG. 17 is an explanatory diagram of a bump arrangement in an electronic component mounting structure (eighth embodiment) according to the present invention.

FIG. 18 is a sectional view of the same electronic component mounting structure (eighth embodiment).

FIG. 19 is an explanatory diagram of a bump arrangement in an electronic component mounting structure (ninth embodiment) according to the present invention.

FIG. 20 is a sectional view of the electronic component mounting structure (ninth embodiment).

FIG. 21 is an explanatory diagram of a bump arrangement in an electronic component mounting structure (tenth embodiment) according to the present invention.

FIG. 22 is the same electronic component mounting structure (tenth embodiment);
FIG.

FIG. 23 is a cross-sectional view of an electronic component mounting structure (eleventh embodiment) according to the present invention.

24 (1) to (4) are process explanatory views of a conventional electronic component mounting method.

25 (1) to (4) are process explanatory views of a conventional electronic component mounting method.

FIG. 26 is a front view of a BGA (Ball Grid Array).

FIG. 27 is a rear view of the BGA (ball grid array).

FIG. 28 is a front view of a conventional electronic component mounting structure.

FIG. 29 is a plan view of a conventional electronic component mounting structure.

FIG. 30 is a front view of a conventional electronic component mounting structure.

FIG. 31 is an enlarged sectional view of a D part in FIG. 30;

[Explanation of symbols]

 Reference Signs List 1 printed wiring board 2 land 2-1 land 2-2 land 2-3 land 2A land forming surface 3 Cu pattern 4 screen mask 4A mask opening 5 solder paste 6 squeegee 7 chip component (electronic mounting component) 8 fillet 10 package component (Electronic mounting component) 10A Lead 11 Back fillet 12 BGA (Electronic mounting component) (semiconductor package) 12A Electrode forming surface 13 Solder ball 14 Bump 15 Electrode 17 Land bonding surface 18 Electrode bonding surface 20 Land forming surface 21 Land forming surface 22 Land Forming surface portion 23 Mask opening forming portion 24 Mask opening forming portion 25 Mask opening forming portion 26 Electrode forming surface portion 27 Electrode forming surface portion 28 Electrode forming surface portion

Claims (16)

[Claims] A land provided on a mounting surface of a printed wiring board is formed in a concave shape, and a terminal side is brought into contact with solder paste supplied to the land to mount an electronic mounting component, and the electronic mounting component is reflowed. An electronic component mounting structure characterized by being soldered to the printed wiring board. 2. The electronic component is a chip component,
2. The electronic component mounting structure according to claim 1, wherein the terminal side of the chip component is soldered by the solder paste supplied to the land. 3. The electronic component mounting according to claim 1, wherein the electronic component is a package component having leads, and the leads of the package component are soldered by the solder paste supplied to the lands. Construction. 4. The electronic package component according to claim 1, wherein the electronic mounting component is a semiconductor package having solder balls arranged on an electrode side, and the solder balls are soldered by the solder paste supplied to the lands. Electronic component mounting structure. 5. An electronic component comprising a semiconductor package in which solder balls are arranged on an electrode side, a land provided on a mounting surface of a printed wiring board is formed in a concave shape, and the solder ball is directly inserted into the land. An electronic component mounting structure characterized by being soldered. 6. An electronic component mounting structure in which a pair of opposing lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, wherein the plurality of bumps are outside the bumps. An electronic component mounting structure characterized in that its diameter and height are increased. 7. An electronic component mounting structure in which respective pairs of a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, and a land formed on the mounting surface is provided. An electronic component mounting structure, wherein a surface is divided into a plurality of land forming surface portions, steps are provided so as to become deeper as those outside the land forming surface portions, and the lands are arranged on the land forming surface portions. 8. The electronic component mounting structure according to claim 7, wherein the outer diameter of the plurality of lands is larger. 9. An electronic component mounting structure in which respective pairs of a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, wherein the plurality of lands are outside the lands. The larger the diameter,
The electrode forming surface of the semiconductor package was formed so as to be higher from the center to the outer periphery, and a large number of the electrodes were arranged on the electrode forming surface, and the outer diameter of these electrodes was increased. An electronic component mounting structure, characterized in that: 10. An electronic component mounting structure in which respective pairs of a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, wherein the plurality of lands are outside the lands. The diameter of the semiconductor package is divided into a plurality of electrode forming surfaces, and a step is provided so that the outer surface of the electrode forming surface becomes higher, and the electrode forming surface is provided with a step. An electronic component mounting structure in which electrodes are arranged, and the diameters of the outside of these electrodes are increased. 11. An electronic component mounting structure in which respective pairs of a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, wherein the plurality of lands are outside the lands. The diameter of the semiconductor package is divided into a plurality of electrode forming surfaces, and a step is provided so that the outer surface of the electrode forming surface becomes higher, and the electrode forming surface is provided with a step. An electronic component mounting structure, wherein electrodes are arranged and all the electrodes have the same size. 12. An electronic component mounting structure in which respective pairs of a plurality of lands provided on a mounting surface of a printed wiring board and a plurality of electrodes of a semiconductor package are connected by bumps, wherein said electrodes are connected to said lands. An electronic component mounting structure, wherein the size of the bump is increased, and the bump has a shape in which a land bonding surface has a conical spread larger than an electrode bonding surface. 13. A land provided on a mounting surface of a printed wiring board is formed into a concave shape, a solder paste is supplied to the land in a printing step, and a terminal side is brought into contact with the solder paste in a mounting step to form an electronic mounting component. An electronic component mounting method, wherein the electronic component is mounted and soldered by reflow in a reflow step. 14. The electronic package component is a semiconductor package in which solder balls are arranged on the electrode side, the land provided on the mounting surface of the printed wiring board is formed in a concave shape, and the solder ball is directly inserted into the land in a mounting step. An electronic component mounting method, wherein the electronic component is soldered by reflow in a reflow step. 15. A solder paste is supplied to a land provided on a mounting surface of a printed wiring board by a printing process, and a terminal is brought into contact with the solder paste in a mounting process to mount an electronic mounting component. An electronic component mounting method for soldering the electronic mounted component, wherein the electronic mounted component is a semiconductor package in which solder balls are arranged on an electrode side, and a plurality of land forming surfaces provided on the mounting surface are provided. It is divided into land forming surface portions, and a step is provided so that the outer side of these land forming surface portions becomes deeper, the lands are arranged on the land forming surface portions, and a thick mask is used as a screen mask used in the printing step. The solder paste is supplied to the lands from the mask openings of the screen mask by using Electronic component mounting method is characterized in that as the amount of feed is increased. 16. A solder paste is supplied to a land provided on a mounting surface of a printed wiring board in a printing step, and a terminal side is brought into contact with the solder paste in a mounting step to mount an electronic mounting component. An electronic component mounting method for soldering the electronic mounted component, wherein the electronic mounted component is a semiconductor package in which solder balls are arranged on an electrode side, and a plurality of land forming surfaces provided on the mounting surface are provided. Divided into land forming surface portions, steps are provided so that the outer ones of these land forming surface portions become deeper, the lands are arranged on the land forming surface portions, and a screen mask used in the printing step has an outer surface. A screen mask having a larger diameter in the mask opening is used, and the solder paste is supplied from the mask opening to the land. , The electronic component mounting method is characterized in that as the solder supply amount as outside of the lands is increased.