JP3896696B2 - Electronic component mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of mounting electronic components whereby bubbles between a circuit board and electronic components can be prevented and troubles due to the bubbles can be effectively avoided. SOLUTION: In a coating step, conductive adhesives 34-37 are coated discretely so that the spacing between the adjacent conductive adhesives 34-37 increases one by one from the centers of conductor lands 22 to their ends. In a mounting step, an IC chip 23 is mounted on the discretely coated conductive adhesives 34-37 wherein first the centers of the conductive lands 22 connect to the adjacent conductive adhesives 34-37 and then other parts from the centers to the ends connect the adjacent conductive adhesives 34-37 one by one, starting from the centers, and air residing at the centers of the conductor lands 22 is sucked out from the centers of the conductor lands 22.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic component mounting method in which an electronic component is mounted in a predetermined mounting region on a circuit board with an adhesive applied by mask printing.
[0002]
[Problems to be solved by the invention]
In recent years, a mounting method has been considered in which an electronic component is mounted on a circuit board by applying an adhesive to the mounting area on the circuit board by mask printing and mounting the electronic component on the mounting area to which the adhesive has been applied. ing.
[0003]
By the way, in this case, when the width of the squeegee moving direction is relatively large at the opening of the mask used in mask printing, when the adhesive is applied on the circuit board, the squeegee moving direction As shown in FIG. 10, when the squeegee 1 moves on the mask 2, a part of the adhesive 4 applied on the circuit board 3, particularly, is applied. There is a risk that the adhesive at the center portion will be scraped off. Therefore, it is assumed that the width of the opening 5 of the mask 2 (indicated by w in FIG. 10) needs to be limited to a certain size (for example, about 2.5 mm or less).
[0004]
In addition, when mounting an electronic component on a circuit board with an adhesive due to such circumstances, if the mounting area of the electronic component is relatively large, as shown in FIG. A plurality of (four in FIG. 11) rectangular openings 6a to 6d that satisfy the above-described conditions are formed in a region corresponding to (a region indicated by a two-dot chain line A in FIG. 11). By using the mask 6, as shown in FIG. 12, it is conceivable to divide and apply the adhesive to the mounting area on the circuit board 7 (area indicated by a two-dot chain line B in FIG. 12).
[0005]
In such a mounting method, after the adhesive is dividedly applied on the circuit board 7 and then the electronic component 8 is mounted, the dividedly applied adhesives 9 to 12 (shown by hatching in FIG. 12). When the pressure is applied to each of the adhesives 9 to 12, the adhesives 9 to 12 spread. However, at this time, when the portion applied to the end side of the mounting region is first connected to the adjacent adhesives 9 to 12 (see (c) and (d) in FIG. 12), the circuit board 7 Then, air remains between the electronic component 8 and the adhesive 13 to generate bubbles 14 (see (e) and (f) in FIG. 12). In some cases, expansion of the bubbles 14 and Due to the shrinkage, the mechanical connection strength between the circuit board 7 and the electronic component 8 may be reduced.
[0006]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent bubbles from being generated between the circuit board and the electronic component when the electronic component is mounted on the circuit board with an adhesive. It is an object of the present invention to provide an electronic component mounting method that can prevent the occurrence of defects caused by the bubbles.
[0007]
[Means for Solving the Problems]
According to the electronic component mounting method recited in claim 1, first, an application step of applying an adhesive to the mounting region is performed. At this time, the mask used in this coating process has a plurality of openings in an area corresponding to the mounting area so that an end side corresponding to the mounting area in the mask portion located between the openings is wider than the center side. In other words, the mask portion is formed with a relatively narrow central side corresponding to the mounting region, and an end side corresponding to the mounting region is formed relatively wide. Therefore, the adhesive is applied with a relatively small distance to the adjacent adhesive on the center side of the mounting area, and is applied with a relatively large distance to the adjacent adhesive on the end side of the mounting area. Will come to be.
[0008]
Next, after this coating process is performed, a mounting process for mounting electronic components on the mounting area is performed. At this time, due to the application process described above being performed, the adhesive is applied with a relatively small distance from the adjacent adhesive on the center side of the mounting area, and with the adjacent adhesive on the end side of the mounting area. In this mounting process, the divided and applied adhesive is first connected to the adhesive adjacent to the central portion of the mounting region, and then the mounting process is performed. A portion on the end side of the mounting area is connected to the adjacent adhesive.
[0009]
Therefore, since the central portion of the mounting area is connected to the adjacent adhesive in this way, the air staying at the central side of the mounting area is discharged outward from the central side of the mounting area. Will come to be. This can prevent air from remaining between the circuit board, the electronic component, and the adhesive, resulting in the formation of bubbles, and as a result, between the circuit board and the electronic component due to expansion and contraction of the bubbles. It is possible to prevent the mechanical connection strength from being lowered.
[0010]
According to the electronic component mounting method described in claim 2, first, an application step of applying an adhesive to the mounting region is performed. At this time, the mask used in the coating process is formed in a taper-like width as the mask portion moves from the center side corresponding to the mounting region to the end side. As it goes to the side, it is applied so that the distance between the adjacent adhesives becomes larger sequentially.
[0011]
Next, after this coating process is performed, a mounting process for mounting electronic components on the mounting area is performed. At this time, since the application process described above has been performed, the adhesive is applied so that the distance from the adjacent adhesive gradually increases from the center side to the end side of the mounting region. When the mounting process is performed, the adhesive that has been dividedly applied is first connected to the adhesive that is adjacent to the central portion of the mounting region, and then the adhesive that is adjacent to the end portion from the central side of the mounting region. The agent is sequentially connected from the central part.
[0012]
Therefore, also in this case, the central portion of the mounting area is connected to the adjacent adhesive, and then the portion from the central side to the end side of the mounting area is adjacent to the adhesive and the central portion. The air staying at the center side of the mounting area is discharged from the center side of the mounting area toward the outside, and the electronic component mounting according to claim 1 described above is mounted. The same effects as the method can be obtained.
[0013]
In addition, in this case, as described above, since the portion from the center side to the end side of the mounting region is sequentially connected from the adjacent adhesive and the central portion, the air remaining on the center side of the mounting region Is smoothly discharged from the center side to the outside of the mounting area.
[0014]
According to the electronic component mounting method of the third aspect, first, a first application step of applying an adhesive to the mounting region is performed. At this time, since the mask used in the first application step has a plurality of openings formed in the region corresponding to the mounting region, the adhesive is applied in a divided manner.
[0015]
Next, after the first application process is performed, a second application process for applying an adhesive to the mounting region is performed. At this time, in the second application step, the adhesive is applied so that the adhesive dividedly applied in the first application step is connected on the center side of the mounting region.
[0016]
Next, after the second coating process is performed, a mounting process for mounting the electronic component in the mounting area is performed. At this time, the adhesive is connected on the center side of the mounting region by the first coating step and the second coating step described above, and the amount of the adhesive is relatively small on the center side of the mounting region. In many cases, the coating is applied in a relatively small amount on the end side of the mounting region, and therefore, when this mounting process is performed, it flows from the center side to the end side of the mounting region.
[0017]
Accordingly, since the adhesive flows in this way from the center side to the end side of the mounting area, the air remaining on the center side of the mounting area is discharged outward from the center side of the mounting area. Also in this case, the same effects as those of the electronic component mounting method described in claims 1 and 2 described above can be obtained.
[0018]
According to the electronic component mounting method described in the fourth aspect, since the second application step is performed using a dispenser, the adhesive can be applied by a known simple method.
[0019]
According to the electronic component mounting method of the fifth aspect, since the adhesive is made conductive, the circuit board and the electronic component can be electrically connected in addition to being mechanically connected.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS.
First, FIG. 2 schematically shows a mounting form of the electronic component obtained by the present embodiment. In FIG. 2, a circuit board 21 is formed by printing and baking a Cu thick film paste material on a ceramic substrate, and a conductor land (mounting area in the present invention) 22 is provided at a predetermined portion thereof. ing. The IC chip (electronic component referred to in the present invention) 23 is bonded onto the conductor land 22 via a conductive adhesive 24. The conductive adhesive 24 is an amine-cured epoxy resin filled with an Ag filler and has a viscosity of 150 Pa · S (Pascal · second).
[0021]
As shown in FIG. 3, such a mounting form is performed by sequentially executing the coating step A1 and the mounting step A2, and the specific contents of the steps A1 and A2 will be described below.
[0022]
First, in application | coating process A1, the conductive adhesive 24 is apply | coated on the conductor land 22 of the circuit board 21 by mask printing. Now, the mask used in the coating step A1 is formed in a pattern as shown in FIG. That is, four openings 26 to 29 are formed in an area corresponding to the conductor land 22 in the mask 25 (area indicated by a two-dot chain line C in FIG. 4). Each mask part 30-33 located between the parts 26-29 is taperingly widened as it goes to the end side from the center side of the area | region corresponding to the conductor land 22, respectively. In this case, the thickness of the mask 25 is 70 μm, and in FIG. 4, a = 0.1 mm, b = 2.0 mm, c = 0.5 mm, and d = 0.3 mm, respectively.
[0023]
Then, mask printing is executed using the mask 25, and conductive adhesives 34 to 37 are applied onto the conductor lands 22 of the circuit board 21, as shown in FIG. At this time, as a printing condition, a metal squeegee is used, the printing load is 1 N, the moving speed of the squeegee is 30 mm / second, on-contact, and the thickness of the conductive adhesives 34 to 37 applied in a divided manner. The thickness (film thickness) is 70 ± 10 μm.
[0024]
Next, in the mounting step A <b> 2, the IC chip 23 is mounted on the conductor lands 22, that is, on the conductive adhesives 34 to 37 that are separately applied on the conductor lands 22. At this time, as mounting conditions, the load is 6 N, and the load application time is 1 second.
[0025]
At this time, the conductive adhesives 34 to 37 are adjacent to the conductive land 34 to 37 from the center side to the end side of the conductor land 22 by performing the coating step A1 as described above. It is applied so that the interval between and increases gradually. Therefore, when the IC chip 23 is mounted on the conductive adhesives 34 to 37, first, the central portion of the conductor land 22 is connected to the adjacent conductive adhesives 34 to 37, and then the center of the conductor land 22. Since the portions from the side to the end side are sequentially connected to the adjacent conductive adhesives 34 to 37 from the central portion, the air remaining on the central side of the conductive land 22 is the central side of the conductive land 22. The liquid is discharged from the outside toward the outside (see (c) and (d) in FIG. 1). In FIG. 1, the IC chip 23 is omitted in (a), (c) and (e).
[0026]
As described above, according to the first embodiment, the intervals between the conductive adhesives 34 to 37 are increased sequentially from the central side to the end side of the conductor land 22. Since the application process A1 for performing the divisional application is performed, and then the mounting process A2 for mounting the IC chip 23 on the conductive adhesives 34 to 37 that have been separately applied is performed. The conductive adhesives 34 to 37 are first connected to the conductive adhesives 34 to 37 adjacent to the central portion of the conductor land 22, and then the portions from the central side to the end side of the conductive land 22 are adjacent. The conductive adhesives 34 to 37 are sequentially connected to the central portion.
[0027]
Along with this, the air remaining on the center side of the conductor land 22 is discharged outward from the center side of the conductor land 22, and therefore, the conductor land 22, the IC chip 23, and the conductive adhesive. It is possible to prevent bubbles from being generated due to air remaining between the conductor land 22 and the mechanical connection strength between the conductor land 22 and the IC chip 23 due to expansion and contraction of the bubbles. Can be prevented.
[0028]
In particular, in this case, by applying the conductive adhesives 34 to 37 so that the distance from the adjacent conductive adhesives 34 to 37 sequentially increases from the center side to the end side of the conductor land 22, As described above, the divided conductive adhesives 34 to 37 are first connected to the adjacent conductive adhesives 34 to 37 at the center of the conductor land 22, and then the center of the conductor land 22. Since the portions from the side to the end side are sequentially connected to the adjacent conductive adhesives 34 to 37 from the central portion, the air remaining on the central side of the conductive land 22 is the central side of the conductive land 22. The liquid is smoothly discharged from the outside toward the outside.
[0029]
Further, in this case, since the conductive adhesives 34 to 37 are used as the adhesive, the conductor land 22 and the IC chip 23 can be electrically connected in addition to being mechanically connected. .
[0030]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different parts will be described.
In the second embodiment, the mask 41 shown in FIG. 5 is used in the coating step A1. Two openings 42 and 43 are formed in an area corresponding to the conductor land 22 in the mask 41 (area indicated by a two-dot chain line D in FIG. 5). The mask portions 44, 45 positioned between 42, 43 are tapered and widened from the center side to the end side of the region corresponding to the conductor land 22. In this case, the thickness of the mask 41 is 70 μm, and in FIG. 5, a = 0.1 mm, b = 2.0 mm, c = 0.5 mm, and d = 0.3 mm, respectively.
[0031]
As described above, according to the second embodiment, the mask 41 is formed in a tapered shape with the mask portions 44 and 45 extending from the center side to the end side of the region corresponding to the conductor land 22. Since the configuration is functionally the same as that of the mask 25 described in the first embodiment, the same function and effect as in the first embodiment can be obtained.
[0032]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different parts will be described.
In the third embodiment, as shown in FIG. 6, the mounting form shown in FIG. 2 is achieved by sequentially executing the first coating process B1, the second coating process B2, and the mounting process B3. Is. Hereinafter, the specific content of each process B1-B3 is demonstrated.
[0033]
First, in 1st application | coating process B1, a part of conductive adhesive 24 is apply | coated on the conductor land 22 of the circuit board 21 by mask printing. Now, the mask used in this coating step is formed in a pattern as shown in FIG. 7, which is the same as that described in “Problems to be Solved by the Invention”. In the region corresponding to the conductor land 22 (the region indicated by the broken line E in FIG. 7), four rectangular openings 52 to 55 are formed. In this case, the thickness of the mask 51 is 70 μm. In FIG. 7, a = 0.1 mm, b = 2.0 mm, and c = 0.5 mm, respectively.
[0034]
Then, mask printing is performed using this mask 51, and conductive adhesives 56 to 59 are applied onto the conductor lands 22 of the circuit board 21, as shown in FIG. Also at this time, as a printing condition, a metal squeegee is used, the printing load is 1.0 N, the moving speed of the squeegee is 30 mm / second, the on-contact, and the conductive adhesives 56 to 50 which are divided and applied The thickness (film thickness) 59 is 70 ± 10 μm.
[0035]
Next, in the second application step B2, the conductive adhesive 60, which is the remaining portion of the conductive adhesive 24, is divided into conductive conductors 56 to 59 by using a dispenser, so that the conductive lands 22 are divided. (See (c) and (d) in FIG. 8).
[0036]
Next, in the mounting step B <b> 3, the IC chip 23 is mounted on the conductor land 22, that is, on the conductive adhesives 56 to 60 applied on the conductor land 22.
Now, at this time, by performing the first application process and the second application process as described above, the conductive adhesives 56 to 59 pass through the conductive adhesive 60 on the center side of the conductor land 22. In addition, the amount of the conductive adhesive 60 applied is large. Therefore, when the IC chip 23 is mounted on the conductive adhesives 56 to 60, the conductive wire adhesive 60 flows from the center side to the end side of the mounting region, so that it remains on the center side of the conductor land 22. The discharged air is discharged from the central side of the conductor land 22 toward the outside (see (e) and (f) in FIG. 9). In FIG. 8, (a), (c) and (e), (g) in FIG. 9, the IC chip 23 is omitted.
[0037]
As described above, according to the third embodiment, the first application step B1 for dividing and applying the conductive adhesives 56 to 59 is performed, and then the divided and applied conductive adhesives 56 to 59 are applied to the conductor lands 22. Since the second application step B2 for applying the conductive adhesive 60 so as to be connected at the center side of the substrate and the mounting step B3 for mounting the IC chip 23 are performed, in the mounting step B3, the conductive wire The adhesive 60 flows from the center side to the end side of the conductor land 22.
[0038]
Along with this, the air remaining on the center side of the conductor land 22 is discharged outward from the center side of the conductor land 22, and therefore, the conductor land 22, the IC chip 23, and the conductive adhesive. It is possible to prevent bubbles from being generated due to air remaining between the conductor land 22 and the mechanical connection strength between the conductor land 22 and the IC chip 23 due to expansion and contraction of the bubbles. Can be prevented.
[0039]
In particular, in this case, since the second application step B2 is performed using a dispenser, the conductive adhesive 60 can be applied by a known simple method.
[0040]
(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
The adhesive is not limited to a conductive adhesive, and an insulating adhesive may be used, that is, a configuration in which a circuit board and an electronic component are mechanically connected only may be used.
[0041]
In the first embodiment and the second embodiment, the number of openings in the mask is not limited to two or four, but may be any other number, and the mask portion may be directed from the center side to the end side. Alternatively, it may be formed in a wide staircase shape.
The electronic components may be mounted on the circuit board by combining the first and second embodiments and the third embodiment.
[Brief description of the drawings]
FIG. 1 is a plan view (a), (c), (e) and sectional views (b), (d), (f) showing the operation of a first embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing a mounting form. FIG. 3 is a flow chart showing a process flow. FIG. 4 is a plan view of a mask. FIG. 5 is a view corresponding to FIG. 6 is a view corresponding to FIG. 3 showing a third embodiment of the present invention. FIG. 7 is a view corresponding to FIG. 4. FIG. 8 is a plan view (a), (c) and sectional views (b), (d) showing the operation.
FIG. 9 is a plan view (e), (g) and sectional views (f), (h) showing the operation.
FIG. 10 is a diagram schematically showing a coating process of a conventional example. FIG. 11 is a view corresponding to FIG. 4. FIG. 12 is a plan view (a), (c), (e) and a sectional view (b) showing the operation. (D), (f)
[Explanation of symbols]
In the drawings, 21 is a circuit board, 22 is a conductor land (mounting region), 23 is an IC chip (electronic component), 24 is a conductive adhesive, 25 is a mask, 26 to 29 are openings, and 30 to 33 are mask portions. , 34 to 37 are conductive adhesives, 41 is a mask, 42 and 43 are openings, 44 and 45 are mask parts, 51 is a mask, 52 to 55 are openings, and 56 to 60 are conductive adhesives.

Claims (5)

In an electronic component mounting method in which an electronic component is mounted on a predetermined mounting area on a circuit board with an adhesive applied by mask printing,
Use a mask in which a plurality of openings are formed such that the end side corresponding to the mounting region in the mask portion located between the openings formed corresponding to the mounting region is wider than the center side. Application process of applying an adhesive to the mounting area,
First, the portion on the center side of the mounting region is connected to the adjacent adhesive, and then the portion from the center side to the end side of the mounting region is sequentially connected to the adjacent adhesive from the center side portion. An electronic component mounting method comprising sequentially performing a mounting step of mounting electronic components in the mounting area.   2. The electron according to claim 1, wherein the coating step is performed using a mask formed in a taper and wider as the mask portion moves from a center side corresponding to the mounting region toward an end side. Component mounting method. In an electronic component mounting method in which an electronic component is mounted on a predetermined mounting area on a circuit board with an adhesive applied by mask printing,
A first application step of applying an adhesive to the mounting region using a mask having a plurality of openings formed in a region corresponding to the mounting region;
A second application step of applying an adhesive so that the adhesive dividedly applied in the first application step is connected on the center side of the mounting region;
An electronic component mounting method comprising sequentially performing a mounting step of mounting the electronic component in the mounting region.   4. The electronic component mounting method according to claim 3, wherein the second application step is performed using a dispenser.   The electronic component mounting method according to claim 1, wherein the adhesive is conductive.

Images