JP2001291952A - Board design method, mounting board manufacturing method, and mounting board - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a board designing method, a mounting board manufacturing method, and a mounting board which can perform cream solder printing without causing printing defects even on fine pitch electrodes and do not cause mounting defects. The purpose is to: SOLUTION: In a board design method for determining an arrangement of electrodes formed on a board on which electronic components are mounted, a pattern hole of a mask plate 2 used for screen-printing cream solder on the electrodes is formed on the mask plate. Regarding the electrode of the type formed in the concave portion 2 d whose upper surface has been removed by a predetermined thickness, the electrode is arranged so that the concave portion 2 d does not exist at two or more positions on the longitudinal line of the squeegee 13 at each moving position of the squeegee 13 at the time of screen printing. Place. Thereby, the followability of the squeegee 13 into the concave portion 2d can be ensured, and the printing failure can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of designing a board for determining the arrangement of electronic components on a board on which electronic components are mounted, a method of manufacturing a mounting board having electronic components mounted on the board, and a mounting board. Things.

[0002]

2. Description of the Related Art In mounting electronic components by soldering, a screen printing method is widely used as a method for supplying solder to electrodes on a substrate. In this method, a cream plate is formed on a surface of an electrode through a pattern hole by moving a squeegee on the mask plate using a mask plate in which a pattern hole is formed according to the opposition of the electrode.

There are various types of electronic components mounted by soldering, and electrodes having various shapes and dimensions are formed on the same mounting board according to the type of each electronic component. The appropriate amount of cream solder, that is, the print thickness differs depending on the type of the electrode. For this reason, in order to realize these different printing thicknesses using the same mask plate, depending on the type of electrode, a pattern hole may be formed in a concave portion obtained by partially etching and removing the upper surface of the mask plate. is there. Hereinafter, screen printing of a board designed by a conventional board designing method will be described with reference to the drawings. FIG. 6 is an explanatory diagram of conventional screen printing.

[0006] In FIG. 6, a mask plate 2 is mounted on a substrate 1. The mask plate 2 is provided with a plurality of pattern holes corresponding to electrodes of a plurality of different types of electronic components. The pattern hole 5a shown in FIG.
Is a pattern hole provided corresponding to an electrode to which a fine-pitch type terminal is to be soldered. A predetermined area on the upper surface of the mask plate 2 is removed by etching to reduce the printing thickness, thereby forming a recess 2d. Have been.
The pattern hole 5a is formed in the recess 2d.

When the squeegee 13 passes over the recess 2d during squeegeeing at the time of screen printing, the distal end portion 13a of the squeegee 13 which is made of an elastic material and has high flexibility.
Is pressed from above into the recess 2 d to push the cream solder 6 into the pattern hole 5 a, and the cream solder 6 in the recess 2 d is scraped off by the tip 13 a of the squeegee 13.

[0006]

However, when the pattern holes 5a formed in the recess 2d are simultaneously present at a plurality of locations on the same line in the longitudinal direction of the squeegee 13 when the squeegee 13 is moved, the following reasons exist. Printing defects are likely to occur. That is, the method of forming the concave portion 2 d for the purpose of realizing different printing thicknesses by the mask plate 2 which originally has the same thickness is based on the tip portion 13 of the squeegee 13.
This is adopted on the premise that squeezing can be normally performed in a state where a is properly pushed into the bottom surface of the concave portion 2d.

However, when the same squeegee 13 is pushed into the plurality of recesses 2d at the same time, the tip 13a of the squeegee 13 does not reach the bottom of the recess 2d as shown in FIG. A gap is likely to be formed between the bottom surface and the tip 13a. When such a gap occurs, printing cannot be performed with a correct printing thickness via the pattern hole 5a in the concave portion 2d, and a printing failure occurs.

When the printing pressure for pressing the squeegee 13 is increased for the purpose of improving the state of the squeegee 13 entering the recess 2d, the pattern hole of a normal size that does not require the recess 2d can be used. As a result, the cream solder 6 protrudes from the lower surface of the mask plate 2 (so-called "bleeding") as a result that the portion 13a easily enters from the upper surface of the pattern hole.

As described above, a conventional substrate on which electronic components are mounted by solder bonding includes a mask plate having a pattern hole formed in a concave portion in which the upper surface of the mask plate is partially removed corresponding to a fine pitch. When printing cream solder on the substrate electrode using
As a result, there is a problem that a mounting failure may be induced.

Accordingly, the present invention provides a board designing method, a mounting board manufacturing method, and a mounting board which can perform cream solder printing on fine-pitch electrodes without causing printing defects and do not cause mounting defects. With the goal.

[0011]

According to a first aspect of the present invention, there is provided a method for designing a board, the method comprising: determining a layout of an electrode formed on a board on which an electronic component is mounted and to which the electronic component is soldered; For an electrode of a type in which a pattern hole of a mask plate used for screen-printing cream solder on the electrode is formed in a concave portion obtained by removing a predetermined thickness from the upper surface of the mask plate, the concave portion is formed at the time of screen printing. The electrodes are arranged so that no two or more electrodes are simultaneously present on the longitudinal line of the squeegee at each moving position of the squeegee.

According to a second aspect of the present invention, there is provided a substrate for mounting electronic parts,
An electronic component mounting substrate in which an electrode to which the electronic component is soldered is formed on a substrate on which the electronic component is mounted,
For an electrode of a type in which a pattern hole of a mask plate used for screen-printing cream solder on the electrode is formed in a concave portion obtained by removing a predetermined thickness from the upper surface of the mask plate, the concave portion has a squeegee at the time of screen printing. The electrodes are arranged so that there are no two or more positions on the longitudinal line of the squeegee at each of the moving positions.

According to a third aspect of the present invention, there is provided a method of manufacturing a mounting substrate, wherein an electronic component is soldered to an electrode formed on the substrate and mounted thereon, wherein the electronic component is soldered. For a type of electrode in which pattern holes of a mask plate used for screen-printing cream solder are formed in a concave portion obtained by removing a predetermined thickness from the upper surface of the mask plate, the concave portion has a movement of a squeegee during screen printing. Determining the electrode arrangement so that there are no more than two places on the longitudinal line of the squeegee at the same time at the position, forming an electrode on the substrate based on the electrode arrangement, and removing a predetermined thickness of the upper surface of the mask plate A mask plate including a pattern hole formed in the concave portion is mounted on a substrate, and a squeegee is moved on the mask plate to move the mask plate. And a step of screen printing a cream solder on the electrode of the substrate, a step of mounting the electronic components on a substrate after the screen printing, a step of the solder joint between the electronic component and the substrate electrode by heating the substrate.

According to a fourth aspect of the present invention, there is provided a mounting substrate formed by soldering an electronic component to an electrode formed on the substrate, wherein cream solder is screen-printed on the electrode to which the electronic component is soldered. For an electrode of the type in which the pattern holes of the mask plate used for the purpose are formed in a concave portion obtained by removing the upper surface of the mask plate by a predetermined thickness, the concave portion is located on the longitudinal line of the squeegee at each moving position of the squeegee during screen printing. Determining the electrode arrangement so as not to exist at two or more places at the same time, forming an electrode on the substrate based on the electrode arrangement, and forming a pattern formed in a concave portion obtained by removing an upper surface of the mask plate by a predetermined thickness. A mask plate including holes is mounted on a substrate, and a squeegee is moved on the mask plate to apply cream half to electrodes of the substrate. A step of screen printing, a step of mounting the electronic components on a substrate after the screen printing,
The electronic component and the electrode of the substrate are soldered by heating the substrate to produce a mounting substrate.

According to the present invention, for an electrode of a type in which a pattern hole is formed in a concave portion obtained by removing the upper surface of a mask plate by a predetermined thickness, the concave portion is formed in a longitudinal direction of the squeegee at each moving position of the squeegee during screen printing. By arranging the electrodes so that two or more electrodes do not exist on the line at the same time, the followability of the squeegee into the concave portion during screen printing can be ensured, and printing defects can be prevented.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a plan view of a substrate for mounting electronic components according to one embodiment of the present invention, FIG. 2A is a plan view of a screen mask according to one embodiment of the present invention, and FIG. Partial sectional view of a screen mask of one embodiment,
3 and 4 are explanatory views of screen printing on a board according to an embodiment of the present invention, and FIG. 5 is an explanatory view of steps in a method of manufacturing a mounting board according to an embodiment of the present invention.

First, an electronic component mounting board 1 on which electronic components are mounted will be described with reference to FIG. In FIG. 1, electrodes for soldering terminals and bumps of electronic components are formed on a resin substrate on the upper surface of a substrate 1. The rectangular regions 1a and 1b shown on the substrate 1 indicate ranges where electrodes for soldering different types of electronic components are formed.

Of these regions, the hatched region 1a is a CSP (Chip Size Packa).
ge) is a fine pitch electrode region in which minute electrodes (see electrodes 7a on the substrate 1 shown in FIG. 3B) for soldering electronic components having fine pitch bumps such as ge) are formed at a narrow pitch. The other region 1b is a normal electrode region where an electrode (see the electrode 7b on the substrate 1 shown in FIG. 3B) for soldering an electronic component having a normal terminal such as a chip component is formed.

Next, referring to FIG. 2, a screen mask used for screen-printing cream solder for solder bonding on each of the electrodes 7a and 7b formed on the substrate 1 shown in FIG. 1 will be described. In FIG. 2A, a screen mask 3 is configured by mounting a mask plate 2 on a holder 4, and a large number of patterns are included in a print range 2c (a range corresponding to the shape of the substrate 1) of the mask plate 2. A hole is formed. When printing is performed using the screen mask 3, the squeegee is moved in the direction of arrow a to print cream solder on the substrate through the pattern holes.

Areas 2a and 2 indicated by broken lines in printing range 2c
“b” indicates a region where a pattern hole is formed corresponding to the regions 1a and 1b of the substrate 1. That is, the area 2a is a fine pitch pattern hole area where a pattern hole 5a for printing cream solder on the fine pitch electrode 7a is formed, and the area 2b is a pattern hole for printing cream solder on the normal electrode 7b. This is a normal pattern hole area where 5b is formed.

Around the area 2a of the fine pitch pattern hole, there is provided a concave portion 2d in which the upper surface of the mask plate 2 is removed by a predetermined thickness by a method such as etching, and the pattern hole is formed as shown in FIG. 5a is recess 2
d is formed on the bottom surface. On the other hand, in the normal pattern hole area 2b, the mask plate 2
The pattern hole 5b is formed through the thickness of the hole as it is.

The concave portion 2d provided around the fine pitch pattern hole region 2a as described above is intended to secure an appropriate printing amount with the same mask plate for each of the different electrodes on the same substrate. . That is, when a mask plate having a thickness suitable for printing an appropriate amount of cream solder on the normal type electrode 7b is used, the printing state becomes unstable for the fine pitch electrode 7a, and the printing amount becomes excessive. Becomes

Therefore, when printing is performed on such different kinds of electrodes using the same screen mask, the mask plate having a thickness corresponding to the electrode to be printed is selected by providing the recess 2d as described above. The same effect can be obtained as in the conventional use. These recesses 2d are arranged such that, at each moving position of the squeegee 13 at the time of screen printing, two or more recesses 2d do not exist on the longitudinal line of the squeegee 13 for the reason described below, ie, in the direction of arrow a. Any orthogonal straight line (L1, L2 ...
・) The arrangement is such that there are no more than two recesses 2d above.

Next, the arrangement of electronic components on the substrate 1, that is, the arrangement of each electrode will be described. In the present embodiment, the electrode arrangement when different types of electronic components are mixed on the same substrate is determined by the following method in consideration of the effect on print quality during screen printing.

First, the screen printing performed using the mask plate 2 having the concave portion 2d on the upper surface as described above will be described with reference to FIGS. The screen printing is performed by a screen printing device as shown in FIG. The substrate 1 is held by a holder 11 provided on a moving table 10, and printing is performed in a state where the substrate 1 is pressed against the lower surface of the mask plate 2 of the screen mask 3.

At the time of printing, the cream solder 6 is supplied onto the mask plate 2 and the squeegee 1
This is performed by moving the squeegee head 12 in the horizontal direction while the cylinder 3 is pressed down by the cylinder 14 onto the upper surface of the mask plate 2. As a result, the cream solder 6 is raked in the traveling direction by the squeegee 13 and the pattern holes 5a,
5b is printed on the electrodes 7a and 7b of the substrate 1 via 5b.
FIG. 3B shows a state where printing is performed in this manner. An appropriate amount of cream solder 6 is printed on each of the electrodes 7a and 7b to which the fine pitch electronic component and the normal electronic component are soldered.

FIG. 4 shows the state of the squeegee 13 when the cream solder 6 is filled in the pattern hole 5a formed in the recess 2d in this screen printing. FIG.
As shown in (a), when the squeegee 13 moves on the concave portion 2d, the squeegee 13 is pressed against the mask plate 2 by the cylinder 14 (applying a printing pressure), whereby a squeegee made of a material having a high elasticity is obtained. 13 tip 13a
Partially penetrates into the concave portion 2d and comes into contact with the bottom surface of the concave portion 2d. When the squeegee 13 moves in this state, the other portion of the mask plate 2 (the pattern hole 5
Similarly to b), the cream solder 6 is scraped by the tip 13a of the squeegee 13 and filled in the pattern hole 5a.

In the screen printing for the pattern hole 5a in the concave portion 2d, in order to obtain an appropriate print quality, first, it is required that the front end portion 13a of the squeegee 13 completely contacts the bottom surface of the concave portion 2d without any gap. Can be In order to realize such a good state, the squeegee 13
That the squeegee 13 does not simultaneously perform squeezing on two or more concave portions 2d during the scraping operation by
That is, the recess 2 into which the tip 13a of the squeegee 13 enters.
It has been empirically confirmed that a good contact state can be obtained if d is always one.

In other words, if the mask plate does not have two or more concave portions 2d on the longitudinal line of the squeegee 13 at each moving position of the squeegee 13 during the screen printing, the printing failure due to the above-described factors is eliminated. Can be prevented. Since the electrode requiring the concave portion 2d corresponds to a specific type of electrode, the above condition is satisfied in the design of the board for determining the arrangement of the electrode to which the terminal of the electronic component is bonded on the board 1. Electrode arrangement is determined as described above.

That is, for an electrode of a type in which the pattern holes of the mask plate 2 used for screen printing are formed in the recesses 2d in which the upper surface of the mask plate 2 is removed by a predetermined thickness, the recesses 2d are formed when the screen printing is performed. At each moving position of the squeegee 13, there should be no more than two locations on the longitudinal line of the squeegee 13 at the same time (FIG.
(See (a)) The electrode arrangement shown in FIG. 1 is determined. This prevents a situation in which the squeegee 13 simultaneously performs squeezing on two or more concave portions 2d at the time of screen printing from the design stage of the substrate.

Next, a method of manufacturing a mounting substrate by mounting electronic components on the substrate 1 on which the arrangement of the electrodes is determined by such a method will be described with reference to FIGS. 3, 4 and 5. FIG.
First, an electrode 7a for soldering a bump of a fine pitch electronic component and an electrode 7b for joining a terminal are formed on the substrate 1 based on the above-described electrode arrangement. Next, the electrodes 7a,
The substrate 1 on which the electrodes 7a and 7b are formed is set on the screen printing apparatus shown in FIG. 3A, and the mask plate 2 on which the pattern holes 5a and 5b corresponding to the electrodes 7a and 7b are formed.
To print the cream solder 6.

As a result, as shown in FIG. 3B, an appropriate amount of the cream solder 6 is printed on each of the electrodes 7a and 7b. At this time, the arrangement of the electronic components on the substrate 1 is determined so that the concave portion 2d does not exist at two or more places on the longitudinal direction line of the squeegee 13 at the same time as described above. Enters the recess 2d with good followability and contacts the bottom surface. Therefore, the cream solder 6 can be filled in the pattern hole 5a in the concave portion 2d in a favorable state. Further, since it is not necessary to excessively increase the printing pressure for pressing the squeegee 13, the cream solder 6 does not protrude due to the excessive printing pressure.

Next, electronic components are mounted on the substrate 1 on which the screen printing of the cream solder 6 has been performed as described above. That is, as shown in FIG. 5A, a CSP electronic component 15 is mounted on the electrode 7a, and a normal chip-type electronic component 16 is mounted on the electrode 7b. At this time, the electrode 7a
Is aligned with the bump 15a of the electronic component 15, and the electrode 7b is aligned with the terminal 16a of the electronic component 16.

Next, the substrate 1 on which the electronic components 15 and 16 are mounted is sent to a reflow process, and the substrate 1 is heated as shown in FIG. As a result, the cream solder 6 is melted, and as shown in FIG.
Then, the terminals 16a are soldered to the electrodes 7b, respectively, to form the soldered portions 6 '. At this time, each electrode 7a, 7
Since a proper amount of the cream solder 6 is supplied to b, a good solder joint 6 ′ having no shape defect is formed,
A mounting board for electronic components having excellent reliability without mounting defects is completed.

[0035]

According to the present invention, for an electrode of a type in which a pattern hole is formed in a concave portion obtained by removing the upper surface of a mask plate by a predetermined thickness, the concave portion is provided at each moving position of the squeegee during screen printing. The arrangement of the electrodes is determined so that two or more electrodes do not exist on the longitudinal direction at the same time, so that the squeegee can follow the inside of the concave portion at the time of screen printing, and printing defects can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a board for mounting electronic components according to an embodiment of the present invention.

2A is a plan view of a screen mask according to one embodiment of the present invention; FIG. 2B is a partial cross-sectional view of the screen mask according to one embodiment of the present invention;

FIG. 3 is an explanatory diagram of screen printing on a substrate according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of screen printing on a substrate according to an embodiment of the present invention.

FIG. 5 is a process explanatory view of a method for manufacturing a mounting board according to an embodiment of the present invention;

FIG. 6 is an explanatory diagram of conventional screen printing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Mask plate 2d Depression 5a, 5b Pattern hole 6 Cream solder 7a, 7b Electrode 13 Squeegee

Claims (4)

[Claims] 1. A method for designing a board which determines an arrangement of electrodes formed on a board on which an electronic component is mounted and to which the electronic component is soldered, and which is used for screen-printing cream solder on the electrode. For the electrode of the type in which the pattern hole of the mask plate to be formed is formed in a concave portion obtained by removing the upper surface of the mask plate by a predetermined thickness, the concave portion is simultaneously positioned on the longitudinal line of the squeegee at each moving position of the squeegee during screen printing. A method for designing a substrate, comprising arranging electrodes so that the electrodes do not exist in more than one place. 2. A substrate for mounting an electronic component on which an electrode to which the electronic component is soldered is formed on a substrate on which the electronic component is mounted, wherein the substrate is used for screen-printing cream solder on the electrode. For an electrode of the type in which the pattern holes of the mask plate are formed in the concave portions obtained by removing the upper surface of the mask plate by a predetermined thickness, the concave portions are simultaneously formed at two positions on the longitudinal line of the squeegee at each moving position of the squeegee during screen printing. A substrate for mounting electronic components, wherein electrodes are arranged so as not to exist. 3. A method of manufacturing a mounting board, wherein an electronic component is solder-bonded to an electrode formed on a substrate and mounted, the screen being used to screen-print cream solder on an electrode to which the electronic component is soldered. For the electrode of the type in which the pattern hole of the mask plate to be formed is formed in a concave portion obtained by removing the upper surface of the mask plate by a predetermined thickness, the concave portion is simultaneously positioned on the longitudinal line of the squeegee at each moving position of the squeegee during screen printing. Including a step of determining an electrode arrangement so as not to be present in more than one place, a step of forming an electrode on a substrate based on the electrode arrangement, and a pattern hole formed in a concave portion obtained by removing an upper surface of the mask plate by a predetermined thickness. A mask plate is mounted on a substrate, and a squeegee is moved on the mask plate to apply cream solder to the electrodes of the substrate. A method of manufacturing a mounting board, comprising: a printing step; a step of mounting an electronic component on the board after the screen printing; and a step of heating the board and soldering the electronic component to an electrode of the board. . 4. A mounting board formed by soldering an electronic component to an electrode formed on a substrate, the mask plate being used for screen-printing cream solder on an electrode to which the electronic component is soldered. For an electrode of the type in which the pattern hole is formed in a concave portion obtained by removing the upper surface of the mask plate by a predetermined thickness, the concave portion does not exist at two or more positions on the longitudinal line of the squeegee at each moving position of the squeegee at the time of screen printing. Determining the electrode arrangement as described above, forming an electrode on the substrate based on the electrode arrangement, and removing the mask plate including a pattern hole formed in a concave portion by removing the upper surface of the mask plate by a predetermined thickness. A step of screen printing cream solder on the electrodes of the substrate by moving the squeegee on the mask plate mounted on the mask plate A step of mounting an electronic component on the substrate after the screen printing, and a step of heating the substrate and soldering the electronic component to the electrode of the substrate. Mounting board.