JP2001053399A - Surface mounted unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a surface mounted unit which allows easy check of a mounted state of a surface mounted device on a printed board, even after the device is mounted on the printed board by disposing the unit so that it overhang the peripheral edge of a package of the surface mounted device. SOLUTION: Alignment patterns 23 formed on the side faces of a BGA device 21 are so disposed, that left and right boundary lines 50a, 50b of each alignment pattern 23 are on the same lines as left and right boundary lines 51a, 51b of each position indication land 24 formed on a printed board 22. In this state, solder balls 3 and a cream solder 5 on the lands 24 are melted by a reflow connection method, etc., and then are cooled to be connected to each other, resulting in completed connection between each of the solder balls 3 and the cream solder 5 on the lands 4 without deviations in positions. Accordingly, by merely checking by visual inspection whether the left and right boundary lines 50a, 50b of each alignment pattern 23 and the left and right boundary lines 51a, 51b of each position indication land 24 are on the same lines, a mounted state can be checked of its guality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting unit comprising a surface mounting device and a printed circuit board, and more particularly, to a surface mounting unit for accurately and easily positioning a surface mounted device on a printed circuit board. About.

[0002]

2. Description of the Related Art Conventionally, in order to mount a surface-mounted device on a printed circuit board at a high density, the surface-mounted device has been made thinner and smaller, a fine pitch of lead terminals drawn out from the device body, and a high pin count. Has been requested. For example, fine pitch and multiple pins are required for surface mount devices (SMD: surface mount device) of the type called SOP (small outline package) or QFP (quad flat package). Have been. However, SOP and QF
In a surface mount device of the type in which a large number of lead terminals protrude from the side of the package body as shown by P, the area occupied on the printed circuit board is increased by the length of the lead terminals protruding laterally from the package body. I do. In any case, this type of surface mount device has a disadvantage that the occupied area on the printed circuit board is increased by the length of the lead terminal, so recently, instead of the above type of surface mount device, A BGA (ball grid array) type or CSP (chip scale package) type surface mount device in which solder balls, gold bumps, etc. are fixed in advance to a plurality of electrodes exposed on the package bottom surface, or a grid on the package bottom surface An LGA (lead grid array) type surface mount device in which electrodes arranged in a shape are exposed is widely used. When mounting BGA type and CSP type surface mount devices (hereinafter, both types are integrated and referred to as BGA devices) and LGA type surface mount devices (hereinafter referred to as LGA devices) on a wiring pattern on a printed circuit board In advance, apply cream solder on the wiring pattern (land) corresponding to each solder ball or each electrode on the bottom surface of the component, and position each solder ball or each electrode so as to correspond to each pad on a one-to-one basis. While placing each device. Such B
Since the GA device or the LGA device has no members protruding to the side of the package, the area occupied on the printed circuit board can be reduced.

[0003] Referring to the drawings, a package of a conventional BGA device and a conventional LGA device and a mounting method thereof will be described. FIG. 3A is a diagram showing a BGA device and a printed board which are conventional surface mount devices. In FIG. 3A, a plurality of electrodes 12 exposed on the bottom surface of the package body 1A of the BGA device 1 include:
Each solder ball 3 is fixed. At the position on the printed circuit board 2 corresponding to each solder ball 3, a land 4 of metal foil is formed by etching or the like, and cream solder 5 is applied on each land 4, and each solder ball 3 is BGA so that it is accurately placed on the
The device 1 is placed on the printed circuit board 2. That is,
The BGA device 1 is fixed to the position of the BGA device 1 ′ indicated by the dotted line on the printed circuit board 2 in FIG. Thereafter, the solder balls 3 and the cream solder 5 are melted by a reflow method or the like, and then the BGA device 1 is connected to the printed circuit board 2 by cooling. FIG. 3B shows an LG having a configuration in which the solder balls 3 fixed to the electrodes 12 of the BGA device of FIG.
A device 11 is shown. This LGA device 11
Is fixed on a land on a printed board (not shown) by a reflow method using cream solder. FIG.
(C) shows a state where the BGA device 1 or the LGA device 11 is mounted on the printed circuit board 2. As shown in FIG. 3C, in the BGA device or the LGA device, since there is no member protruding to the side of the package body 1A, the area occupied on the printed circuit board 2 is smaller than the package. This is only the area occupied by the main body 1A.

[0004]

However, the BGA
When connecting the device 1 or the LGA device 11 to the printed circuit board 2, the solder balls 3 or the leads 12 connected to the lands 4 on the printed circuit board 2 are hidden by the bottom surface of the surface mounting device 1 or 11 body. There is a problem that the quality of the soldered state cannot be visually checked after the mounting on the printed circuit board 2 is completed. For this reason, in order to confirm the mounting state of the mounted BGA device 1 or LGA device 11, an inspection involving many man-hours is required, which causes a decrease in productivity. SUMMARY OF THE INVENTION The present invention of claim 1 has been made in order to solve the above-described conventional problems, and provides a surface mounting unit that allows easy checking of a mounting state on a printed circuit board even after mounting on a printed circuit board. The purpose is to do. Further, when mounting the conventional BGA device 1 on the printed circuit board 2, the lands 4 and the electrodes 12 on the package side are connected by using the cream solder 5 and the solder balls 3, so that sufficient connection strength can be obtained. On the other hand, in the case of the LGA device 11, since the planar land 4 and the planar electrode 12 are merely connected using the cream solder 5, the connection strength is weakened. That is, in the case of the LGA device 11, there is a problem that connection reliability is reduced. Therefore, conventionally, when connecting to the printed circuit board 2 using the LGA device 11, the connection strength between the two has been reinforced by using a resin (by underfilling) to improve the connection reliability. The present invention of claim 2 has been made in order to solve the conventional problems as described above, and it is an object of the present invention to provide a method of mounting a surface mounting device that does not require reinforcement of connection strength using a resin or the like. Aim.

[0005]

According to one aspect of the present invention, there is provided a surface mounting device having a plurality of surface mounting electrodes on at least one surface of a package.
A printed circuit board having a plurality of lands on the surface thereof connected to the respective electrodes provided on the package in a one-to-one manner, wherein at least one electrode is provided on at least one side surface of the package of the surface-mounted device. An alignment pattern for indicating the position of the row is provided, and a position indicating land for indicating the position of at least one land row is provided on the surface of the printed circuit board, and the position indicating land is a regular position on the printed circuit board. When the surface mounting device is mounted on the device, the device is arranged at a position protruding from the outer peripheral edge of the package of the surface mounting device.
The invention according to claim 2 is such that a part of the alignment pattern is extended to the one surface of the package to be a connection reinforcing part, and a part of the position display land is in one-to-one correspondence with the connection reinforcing part on the package side. The connection reinforcing portion is characterized in that each connection reinforcing portion is connected by soldering when each electrode and each land are connected by soldering.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a block diagram showing an overall configuration of a package of a BGA device and a printed board constituting a surface mounting unit according to a first embodiment of the present invention. In FIGS. 1 and 2, the same reference numerals are given to portions having the same functions as those of the conventional surface mount device and the printed circuit board shown in FIG. 3, and duplicate description will be omitted. FIG. 1 shows a surface mount device B of the present embodiment.
Package and printed circuit board 22 of GA device 21
It is shown. In FIG. 1A, solder balls 3 are fixed to a plurality of electrodes 12 arranged vertically and horizontally on the bottom surface of a package body 21A of a BGA device 21. The lands 4 are formed on the printed circuit board 22 at positions corresponding to the respective electrodes 12, and cream solder 5 is applied on the lands 4 for reflow connection. In the present embodiment, a positioning pattern 23 is provided on the side surface of the package body 21A of the BGA device 21 so as to indicate the positions of the vertical rows 3a and the horizontal rows 3b of the solder balls 3. The alignment pattern 23 is formed simultaneously when the electrode 12 is formed by etching or vapor deposition. By forming the alignment pattern 23 on the externally visible side surface in this way, unlike the case where an alignment pattern or the like is later printed on a silk screen in accordance with the position of each electrode 12, the row of the electrodes 12 is formed. The situation where the alignment pattern 23 is misaligned from (the same as the row 3a of the solder balls 3 in the case of the present embodiment) is eliminated. In this embodiment, since the solder balls are formed in five rows and four rows as shown in FIG. 1, the alignment pattern 23 is formed on an extension of each of the columns and rows. Although FIG. 1A shows the alignment pattern 23 formed on only one side surface,
The alignment patterns 23 are provided on all side surfaces for each row.

In this embodiment, the alignment pattern 23 is formed so as to correspond to all columns and rows of the electrodes 12. For example, the outermost column in each column 3a of the solder balls 3, ie, the outermost column, Alternatively, the alignment pattern 23 may be provided only for the column 3a1 closest to both ends of one side surface of the package body 21A. in this way,
It is also effective to provide one alignment pattern 23 on each side of the package body 21A of the BGA device 21. This is because, as described above, since the electrode 12 and the alignment pattern 23 are formed at the same time without any positional deviation, the positional deviation between each column 3 a of the solder balls 3 formed on the electrode 12 and the alignment pattern 23. Therefore, the solder ball 3 and the alignment pattern 23
Is not changed from the positional relationship of the design values, and if there is at least one alignment pattern 23 on each side, alignment with a position display land 24 described later can be performed. is there. In this case, the same number of position display lands 24 on the printed circuit board to be described later may be provided at the corresponding positions. The relationship between each row 3b of the solder balls and the alignment pattern 23 is the same as above.

Next, a position indicating land 24 is formed on the surface of the printed circuit board 22 facing the alignment pattern 23 provided on the package body 21A. The position indicating lands 24 are formed at the same time when the lands 4 are formed on the printed board by etching or vapor deposition. By forming the position display lands 24 on the surface of the substrate corresponding to the vertical or horizontal rows of the lands, the position display lands 24 are not displaced from the rows of the lands 4. The shape of this position display land 24 is
At least the width 51 is the width 5 of the alignment pattern 23.
0, and the positions at which the position display lands 24 are formed on the printed circuit board 22 correspond one-to-one to the position alignment lands 24 with the respective alignment patterns 23 on the package body side. In addition, when the BGA device 21 is mounted on the printed circuit board 22, the position display lands 24 are located at positions protruding outward from the outer peripheral edge of the BGA device 21 (visible positions). The relationship between the vertical width 52 of the position display land 24 and the width of the pattern 23 is the same. Thus, the position display lands 24 are formed, and the left and right boundary lines 50a and 50b indicating the width 50 of the alignment pattern 23 and the left and right boundary lines 51a and 51b indicating the width 51 of the position display lands 24 are on the same line. By arranging the BGA device 21 in such a manner, each solder ball 3 and the cream solder 5 on each land 4 are in a position directly facing each other.
As shown in the BGA device 21 ′ of FIG. Therefore, at the time of mounting, when mounting the BGA device 21 on the printed circuit board 22, the left and right boundary lines 50a and 50b indicating the width 50 of each alignment pattern 23 and the left and right boundary lines 51a and 51b of the position display land 24 Are arranged so as to be located on the same line, the solder balls 3 and the cream solder 5 are melted by reflow or the like, and the BGA device 21 is mounted on the printed circuit board 22.

FIG. 1B shows a BG on a printed circuit board 22.
This shows a state in which the A device 21 is mounted. As shown in FIG. 1B, the left and right border lines 50 of the alignment pattern 23 provided on the side surface of the BGA device 21.
a, 50b and the left and right boundary lines 51a, 51b of the position display lands 24 provided on the printed circuit board 22 are arranged so as to be on the same line. In this state, the solder balls 3 and the cream solder 5 on the lands 4 are melted by a reflow connection method or the like and then cooled to complete the connection, so that each of the solder balls 3 and the cream solder 5 on the lands 4 are misaligned. Connected without having to connect. Therefore, according to the present embodiment, the BGA device 2
1 is mounted, the left and right borders 50a and 50b of the alignment pattern 23 and the left and right borders 51a and 51b of the position display lands 24 provided on the printed circuit board 22 are each on the same line. Only by visual confirmation, it is possible to accurately confirm whether or not the BGA device 21 on the printed circuit board 22 is correctly mounted at the connection position, thereby facilitating the confirmation.

FIG. 2A is a diagram showing the overall configuration of a package and a printed board of an LGA device according to a second embodiment of the present invention. A plurality of electrodes 12 are arranged in a grid on the bottom surface of the package body 31A of the LGA device 31. Also, on the printed circuit board 32, each electrode 12
The lands 4 are formed at the positions corresponding to the above, and a cream solder 5 for reflow connection is applied on each of the lands 4. Further, in the present embodiment, the side faces of the package body 31A of the LGA device 31
a, an alignment pattern 33 is provided to indicate each position of the row 12b. This alignment pattern 33
Is formed at the same time when the electrode 12 is formed by etching or vapor deposition. By forming the alignment pattern 33 in this way, the alignment pattern 33 does not shift from the row of the electrodes 12.
In the present embodiment, as shown in FIG. 2A, the electrodes 12 are formed in five columns and four columns, so that the alignment pattern 33 is formed on an extension of each column 12a and each row 12b. Is done. Although FIG. 2A shows the alignment pattern 33 formed on only one side surface,
The alignment pattern 33 is provided on all side surfaces. Further, in the present embodiment, the alignment pattern 33 provided on each side of the LGA device 31 includes the electrode 12 from each side.
Is provided so as to wrap around to the bottom surface where is provided. The portion that goes around the bottom surface of the alignment pattern 33 is referred to as a connection reinforcing portion 33a. This is because not only the alignment pattern 33 is used as a mere display unit, but also the connection reinforcing portion 3 for solder connection with a position display land 34 described later.
3a. Also, the alignment pattern 33 of the present embodiment may be provided corresponding to only the column 12a-1 closest to both ends of one side surface of the package body 31a for the same reason as in the first embodiment.
One (or two or more) alignment patterns 33 may be provided at desired positions on each side surface of the package body 31A of the GA device 31. Note that column 12a
The same applies to row 12b.

Next, a position display land 34 is formed on the surface of the printed circuit board 32 facing the alignment pattern 33 provided on the package body 31A. The position indicating lands 34 are formed simultaneously when the lands 4 are formed by etching or vapor deposition. By forming the position display lands 34 in this manner, the problem that the position display lands 34 are displaced from the row of the lands 4 is eliminated. The shape of the position display lands 34 is such that at least the horizontal width 51 is the same as the horizontal width 50 of the alignment pattern 33, and the position at which each position display land 34 is formed on the printed circuit board 32 is
The position display lands 34 correspond one-to-one, and when the LGA device 31 is mounted on the printed circuit board 32, each position display land 34 is set to a position protruding outward from the outer peripheral edge of the LGA device 31. However, in the present embodiment, since the connection reinforcing portion 33a is provided in the alignment pattern 33, the connection reinforcing portion 34a is formed on the surface of the printed circuit board 32 facing the connection reinforcing portion 33a so as to be continuous with each position display land 34. Is formed. The connection reinforcing portion 34a corresponds to the connection reinforcing portion 33a, and the surface mounting device can be firmly fixed on a printed circuit board by connecting them by soldering without performing reinforcement using a resin. It becomes possible. Thus, the position display land 34 is formed, and the width 50 of the alignment pattern 33 is set.
Boundary lines 50a and 50b indicating the position and the position display land 3
By arranging the LGA device 31 such that the left and right border lines 51a and 51b indicating the horizontal width 51 of each of the LADs 4 are on the same line, each electrode 12 and the cream solder 5 on each of the lands 4 come to a position directly facing each other. LGA device 3
1 is correctly mounted on the printed circuit board 32 as shown in the LGA device 31 'of FIG.

FIG. 2B is a diagram showing the overall configuration of a package and a printed board of an LGA device according to a third embodiment of the present invention. A plurality of electrodes 12 are exposed on the bottom surface of the package body 41a of the LGA device 41. The lands 4 are formed on the printed circuit board 42 at positions corresponding to the respective electrodes 12, and the cream solder 5 is applied on the lands 4. In the present embodiment, an alignment pattern 43 is provided on the side surface of the package body 41A of the LGA device 41 so as to indicate the positions of the columns 12a and the rows 12b of the electrodes 12. The alignment pattern 43 is formed simultaneously with the formation of the electrode 12 by etching or vapor deposition. The effect is to prevent the alignment pattern 43 from being displaced from the row of the electrodes 12 as in the above embodiments. In this embodiment, as shown in FIG. 2B, the electrodes 12 are formed in five columns and four columns, so that the alignment pattern 43 is formed in each column 12a and each row 12a.
formed on extension of b. In addition, in FIG.
Although the alignment pattern 43 formed only on the side surface is shown, the alignment pattern 43 is provided on all side surfaces. In the present embodiment, the alignment pattern 43 provided on each side of the LGA device 41 is
Unlike the embodiment of (a), the electrodes 12 are provided so as not to go around from the side surfaces to the bottom surface on which the electrodes 12 are provided.
Further, the alignment pattern 43 of the present embodiment is also the same as the package body 4 for the same reason as in the first and second embodiments.
The alignment pattern 43 corresponding to only the column 12a-1 closest to both ends of one side surface of the first side 1a or only the other portion.
May be provided, and one alignment pattern 43 may be provided on each side surface of the package body 41A of the LGA device 41.

Next, a position display land 44 is formed on the surface of the printed circuit board 42 facing the alignment pattern 43 provided on the package body 41A. The position indicating land 44 is formed at the same time when the land 4 is formed by etching or vapor deposition. By forming the position display lands 44 in this manner, the position display lands 44 do not shift from the rows of the lands 4.
The shape of the position display land 44 has at least a width 51.
Are made equal to the width 50 of the alignment pattern 43, and each position display land 44 is
The position formed on the LGA device 41 is such that the position display lands 44 correspond to the respective alignment patterns 43 on a one-to-one basis, and when the LGA device 41 is mounted on the printed circuit board 42, It is set to a position protruding outward from the outer peripheral edge. In addition, unlike the embodiment of FIG. 2A, the position indicating land 44 of the present embodiment does not have the alignment pattern 43 wrapping around the bottom surface of the LGA device 41, so that no land facing it is formed. The position indication lands 44 are formed in this manner, and the left and right border lines 50a, 5a indicating the width 50 of the alignment pattern 43 are formed.
0b and the left and right boundary lines 51a and 51b indicating the horizontal width 51 of the position display land 44 are aligned on the same line.
By arranging the device 41, each electrode 12 and the cream solder 5 on each land 4 become a position facing each other,
As a result, the LGA device 41 is correctly mounted on the printed circuit board 42 as shown in the LGA device 41 'of FIG. It should be noted that what has been said about the column 12a applies to the row 12b as well.

Next, FIG. 2C shows a state where the LGA device 31 is mounted on the printed circuit board 32 shown in FIG. 2A. In FIG. 2C, reference numerals shown in parentheses denote printed circuit boards 42 and LG shown in FIG.
A code corresponding to the A device 41. This FIG. 2 (c)
As shown in the figure, the left and right border lines 50a and 50b of the alignment pattern 33 (43) provided on the side surface of the LGA device 31 (41) and the position display land 34 (provided on the printed board 32 (42)). 44) Left and right border 51
a and 51b are arranged on the same line. In this state, the cream solder 5 on the land 4 is melted and connected by reflow or the like, so that each electrode 12 and the cream solder 5 on each land 4 are connected without displacement. Therefore, according to the present embodiment, even after mounting the LGA device 31 (41) on the printed circuit board 32 (42), the left and right border lines 50a and 50b of the alignment pattern 33 (43) and the printed circuit board 32 (42). Left and right border line 5 of position display land 34 (44) provided on top
It is necessary to confirm whether or not the LGA device 31 (41) on the printed circuit board 32 (42) is correctly mounted at the connection position only by confirming whether or not the LGA devices 31a and 51b are on the same line. And the confirmation becomes easy. In the present embodiment, as shown in FIG. 2C, the alignment leads 33 (43) and the position display lands 34 (4)
4) can be connected by the solder 35 (45). Therefore, when mounting the LGA device 31 (41) on the printed circuit board 32 (42),
Even if the cream solder 5 on the land 4 is melted and connected by reflow or the like, the connection strength cannot be sufficiently obtained, and the alignment pattern 33 (4
3) and the position indicating land 34 (44) are
By the connection according to (45), sufficient strength can be obtained. Therefore, by using this embodiment, it is possible to eliminate the reinforcement of the connection strength using the resin for improving the connection reliability.

[0015]

As described above, according to the first aspect of the present invention, the position of an arbitrary land or pattern on a printed circuit board can be compared with the alignment pattern indicating the electrode provided on the surface mount device. To provide a surface mount unit that makes it easy to check the connection position of a surface mount device on a printed circuit board and to check the mounting state on the board even after the surface mount device is mounted on the printed circuit board. Can be. Also, it is only necessary to check whether the left and right borders of the alignment pattern and the left and right borders of the position display lands provided on the printed board are on the same line, and the connection position of the surface mount device on the printed board is determined. Therefore, it is possible to provide a surface mount unit that can easily check the mounting state on the board even after the surface mount device is mounted on the printed board. According to the second aspect of the present invention, since the positioning electrode and the position indicating land are connected by soldering, it is possible to eliminate the reinforcement of the connection strength using a resin for improving the connection reliability of the surface mount device.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a surface mount unit according to a first embodiment of the present invention.

FIG. 2A is a block diagram showing the entire configuration of a package and a printed board of an LGA device according to a second embodiment of the present invention, and FIG. 2B is an LGA according to a third embodiment of the present invention;
FIG. 3 is a block diagram illustrating the overall configuration of a device package and a printed board, and FIG. 3C illustrates a state in which an LGA device is mounted on the printed board.

FIGS. 3A to 3C are diagrams showing a conventional surface mount device and a printed circuit board (and pads).

[Explanation of symbols]

1, 21, 21 '... BGA device (surface mount device), 2, 22, 32, 42 ... printed circuit board, 3
... Solder ball, 4 ... Land, 5 ... Cream solder, 11, 31, 31 ', 41, 41' ... L
GA device (surface mount device), 12 ... electrode,
23 ... positioning pattern, 24, 34, 44 ...
・ Position display land, 33 ・ ・ ・ Positioning pattern, 3
5 ... Solder

Claims (2)

[Claims] 1. A surface mount device having a plurality of electrodes for surface mounting on at least one surface of a package, a printed circuit board provided on the surface with a plurality of lands connected one-to-one with each electrode provided on the package, In a surface mounting unit comprising: a positioning pattern for indicating a position of at least one electrode row on at least one side surface of the package of the surface mounting device; and at least one land row on the surface of the printed circuit board. Position display land is provided to indicate the position of the surface mount device, and the position display land is disposed at a position protruding from the outer peripheral edge of the package of the surface mount device when the surface mount device is mounted at a regular position on the printed circuit board. A surface mount unit characterized by the following. 2. A part of the alignment pattern is extended to the one surface of the package to form a connection reinforcing part,
A part of the position display lands is a connection reinforcement part corresponding to the connection reinforcement part on the package side in a one-to-one correspondence, and each connection reinforcement part is configured to be solder-connected when each electrode and each land are connected by solder. The surface mount unit according to claim 1, wherein: