JPH10321998A - Printed wiring board and part soldering structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize reliable soldering of a large size capacitor in a printed wiring board. SOLUTION: A large land 11A for a large-size capacitor 20 has an rectangular outline having a size, corresponding to the size of a large-size electrode 21 and also having two slits 40, 41 at a part of the internal side. The land 11A, when viewed in the direction Y, has a structure such that the land 42, slit 40, land 43 and slit 31 and land 44 are arranged. The cream solder embedding the slits 40, 41 among the cream solder layer is collected, when it is solved, to the land portions 42, 43, 44. Thereby amount of solder on the lands 42, 43, 44 increases so that the large-size electrode 21-1 of the large-size capacitor 20 and the large land 11A can be soldered reliably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a component soldering structure, and more particularly to a printed wiring board and a component soldering structure on which surface-mounted electronic components are soldered and surface-mounted. In general, for a surface-mounted electronic component, a printed wiring board was prepared by printing and applying cream solder all together on the surface of each land of the printed wiring board using a mask, and the cream solder was applied. Temporarily fix the electronic components on the printed wiring board with an adhesive or the like, mount them, and melt the cream solder through a reflow oven.
Soldered by reflow soldering. In addition, small-sized electronic components having small electrodes and large-sized electronic components having large electrodes are mixed in the printed wiring board. It is important that both small and large electronic components are soldered with good reliability.

[0002]

2. Description of the Related Art FIG. 7 shows a part of a conventional printed wiring board 10 in an enlarged manner. Reference numeral 11 denotes a large land for a large-sized capacitor 20. Large size capacitor 2
0 has a large-sized electrode 21, and the land 11 has a size corresponding to this. Reference numeral 12 denotes a small land for a small-sized capacitor 30. The small-sized capacitor 30 has a small-sized electrode 31,
The land 12 has a size corresponding to this.

[0003] The large land 11 is simply a larger version of the small land 12. The large-sized capacitor 20 and the small-sized capacitor 21 are soldered on the printed wiring board 10 by reflow soldering. Prior to the reflow soldering, cream solder is collectively printed on the surface of each land 11 and 12 on the printed wiring board 10 using a mask (not shown) as shown in FIG. And apply. Reference numeral 15 denotes a cream solder layer applied on the lands 11 and 12. FIG. 8B shows the solder 16 when the cream solder layer 15 is heated and melted and solidified without mounting the capacitor 20.
The solder 16 spreads over the entire surface of the lands 11 and 12, and has a thickness of t2.

As shown in FIG. 9, a large-sized capacitor 20 is connected to each electrode 21 by solder 17-1 and 17-2.
-1, 21-2 are fixed to the land 11 by soldering. If the thickness of the applied cream solder layer 15 is too large, the solder in the small-sized capacitor 21 becomes excessive, and soldering failure occurs. Therefore, the thickness t1 of the cream solder layer 15 is smaller than that of the small-sized capacitor 21.
(Small size electrode 31) has an appropriate thickness.

[0005]

For this reason, in the case of the large-sized capacitor 20, the solder becomes insufficient in some cases, and the solder 17-2 for fixing the left electrode 21-2 in FIG. Thus, the solder does not protrude from the electrode 21-2 to the outside and stays below the electrode 21-2,
Therefore, the fillet was not formed, and the soldering strength might be insufficient. Note that normal soldering refers to a state in which the solder protrudes outward from the electrode 21-1 and the fillet 17a is firmly formed, as in the case of the soldering of the right electrode 21-1 in FIG. .

In order to solve the above-mentioned problem, a mask for the small land 12 and a mask for the large land 11 are prepared, and cream solder printing is performed twice. In the case of using a solder paste, it is conceivable that the thickness of the solder paste is made different from that of printing the cream solder thicker.However, this increases the man-hours and increases the manufacturing cost of electronic equipment. There is also a limit to printing thicker solder.

Accordingly, an object of the present invention is to provide a printed wiring board and a component soldering structure which solve the above problems.

[0008]

According to a first aspect of the present invention, there is provided a printed wiring board having a land used for soldering a component, wherein the land is provided with a solder having a molten solder not attached to a part thereof. This has a configuration in which a rejected area is formed, and the remaining portion forms a land portion to which the molten solder is attached.

According to a second aspect of the present invention, in the first aspect, the solder adhesion rejection region has a shape that is long in a direction in which the paired lands are arranged, and the land portion is formed of the paired lands. It is configured to have a shape that is long in the arranged direction. According to a third aspect of the present invention, the surface mounting type component is configured such that its electrodes are soldered to the lands of the printed wiring board according to the first or second aspect.

[0010]

FIG. 1 shows a printed wiring board 10A according to a first embodiment of the present invention. 1 to 4, the same components as those shown in FIGS. 7 to 9 are denoted by the same reference numerals, and portions corresponding to the components shown in FIGS. Assign a sign.

Reference numeral 11A denotes a large land for the large-sized capacitor 20. The large-sized capacitor 20 has a large-sized electrode 21, and the land 11A has a size corresponding to this. Reference numeral 12 denotes a small land for a small-sized capacitor 30. The small-sized capacitor 30 has a small-sized electrode 31, and the land 12 has a size corresponding to this. The large land 11A and the small land 12 are provided on the substrate body 13.
And are mixed. Each land 11A, 12 is located at the tip of a wiring pattern (not shown).

The large land 11A is paired with two lands.
X is the direction in which the large lands 11 forming a pair are arranged.
Y is a direction orthogonal to X. As shown in FIG. 2A, the large land 11A has a rectangular outline, has a size corresponding to the size of the large-sized electrode 21, and has two slits 40 and 41 in an inner portion. Having a pattern having The width of each of the slits 40 and 41 is w1.
And has a shape that is long in the X direction and is apart from the dimension a in the Y direction. Therefore, when viewed in the Y direction, the large land 11A has the land 42, the slit 40, and the land 4
3, a configuration in which the slit 41 and the land portion 44 are arranged, that is, a configuration in which the three land portions 42, 43, and 44 are arranged at intervals of the width w1. Between the adjacent land portions are landless portions 45 and 46 having no land. The base of the landless portions 45 and 46 is a solder resist surface 47 and repels solder. The landless portions 45 and 46 (slits 40 and 41) constitute a “solder refusal area” in the claims. Further, since the slits 40 and 41 have a shape elongated in the X direction, the land portions 42 and 43,
44 also has a shape elongated in the X direction.

The large-sized capacitor 20 and the small-sized capacitor 21 are soldered on the printed wiring board 10A by reflow soldering. Prior to the reflow soldering, as shown in FIG. 2B, each land 1 on the printed wiring board 10A using a mask (not shown).
Cream solder is collectively printed and applied to the surfaces of 1A and 12. Reference numeral 15 denotes a cream solder layer applied to the lands 11A and 12A. Reference numeral 15a denotes cream solder filling the landless portions 45 and 46 of the land 11A.

If the cream solder layer 15 is heated and melted and solidified without mounting the capacitors 20 and 30, the result is as shown in FIG. 2C. Land 12
, The solder 16 is spread over the entire surface of the land 12, and the thickness is t2. Next, the land 11A will be described.

The cream solder layer 15 on each of the lands 42, 43, and 44 is melted and then melted.
Stay on 44. When the cream solder 15a filling the landless portion 45 is melted, it is repelled by the solder resist surface 47, and approximately half is gathered on the land portion 42 as indicated by an arrow 50 in FIG. Almost half is gathered on the land 43 as shown by the arrow 51.
When the cream solder 15b filling the non-land portion 46 is melted, the cream solder 15b is repelled by the solder resist surface 47, and approximately half of the land portion 43 is indicated by an arrow 52 in FIG.
The other half is drawn to the land portion 44 as shown by an arrow 53 and collected. Thereby, each land part 42, 43, 4
The solder 16A on 4 has a thickness of t3 slightly thicker than t2.

When the land 11A is scanned in the Y direction, portions where solder is present and portions where no or little solder is present are alternately present, and portions where solder is present are smaller than before. It has a thick thickness t3. As shown in FIG.
Each electrode 21- is connected by the solder 17A-1, 17A-2.
1, 21-2 are fixed to the land 11A by soldering. Here, the portion where the solder is present has a thickness t3 that is thicker than before, and since there is a larger amount than before, each of the solders 17A-1 and 17A-2 is connected to the electrode 21-1. , 21-2, and fillet 17 a is attached to each land portion 4 as shown in FIGS. 3 and 4.
It is firmly formed every 2, 43, 44. Therefore, the large-sized capacitor 20 is soldered and fixed with high reliability similarly to the small-sized capacitor 30.

FIG. 5 shows a part of a printed wiring board 10B according to a second embodiment of the present invention. Large land 11B
Has a rectangular outline, has a size corresponding to the size of the large-sized electrode 21 described above, and has two solder resist bands 60 and 61 having a width w1 printed with a solder resist and having a width w1. It is a configuration that crosses. Of the lands, the portions of the solder resist strips 60 and 61 correspond to the solder resist strips 60 and 6.
Hidden by one. 62, 63 and 64 are exposed lands. When the cream solder on the solder resist strips 60, 61 is melted, the cream solder is repelled by the solder resist strips 60, 61 and collected on the lands 62, 63, 64. Therefore, the amount of solder is sufficient when looking at the local parts to be soldered, and even for the large-sized capacitor 20, the fillet is firmly formed at the soldered part, and the large-sized capacitor 20 is small. As in the case of the capacitor 30 described above. The solder resist strips 60 and 61 constitute the “solder refusal area” in the claims.

FIG. 6 shows a part of a printed wiring board 10C according to a third embodiment of the present invention. Large land 11C
Has a rectangular outline, a size corresponding to the size of the large-sized electrode 21 described above, and a silk-printed width w
This is a configuration in which two printing bands 70 and 71 having the number 1 cross in the X direction. The printing bands 70 and 71 of the land are hidden by the printing bands 70 and 71. 72, 7
Numerals 3 and 74 are exposed lands. Printing belt 70,
When the cream solder on 71 is melted, the printed bands 70, 71
And are gathered on the lands 72, 73 and 74. Therefore, the amount of solder is sufficient when looking at the local parts to be soldered, and even for the large-sized capacitor 20, the fillet is firmly formed at the soldered part, and the large-sized capacitor 20 is small. As in the case of the capacitor 30 described above. The printing bands 70 and 71 constitute the “solder refusal area” in the claims section.

The printed wiring boards 10, 1 of the present invention
0A to 10C are not limited to reflow soldering in which cream solder is applied and passed through a reflow furnace, and printed circuit boards 10, 10A to 10C on which electronic components are temporarily fixed by an adhesive.
The present invention can also be applied to dip soldering which is applied to a solder bath in which C is melted, and has the same effect as described above. Note that the “solder refusal area” formed on the land is not limited to a property in which no solder is attached, and may have a property in which solder is not easily attached.

[0020]

As described above, according to the first aspect of the present invention, a land used for soldering a component has a solder adhesion rejection area where a molten solder does not adhere or hardly adheres to a part of the land. With this configuration, when performing reflow soldering, when the cream solder applied to the lands melts, the solder on the solder refusal area is gathered on the lands, and thus fillets are formed on the lands. It is in a state where a large amount of solder which is enough to be formed is put on it,
Even in the case of a component having a large electrode size, a soldered portion can be firmly soldered like a component having a small electrode size in such a manner that a fillet is formed at a soldered portion. In other words, it is possible to use limited solder effectively by gathering the solder on the land portion, and by using the limited solder effectively, a large component that has been liable to be short of solder in the past. Can be soldered firmly.

According to the second aspect of the present invention, the solder attachment refusal region has a shape that is long in the direction in which the paired lands are arranged, and the land portion has a shape that is long in the direction in which the paired lands are arranged. Therefore, when a large component is soldered, a fillet of the solder can be formed at the longitudinal end of the large component. by this,
It is possible to securely solder a large component, which was apt to be short of solder in the past.

According to the third aspect of the present invention, since the surface mounting type component is configured such that its electrodes are soldered to the lands of the printed wiring board according to the first or second aspect, limited solder is provided. By effectively using, it is possible to realize an electronic device in which a large component that has been liable to be short of solder in the past is securely soldered.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of gathering molten solder when cream solder is applied to a land of FIG. 1 and melted;

FIG. 3 is a view showing a state of soldering when a capacitor is mounted on the printed wiring board of FIG. 1;

FIG. 4 is a perspective view showing a state of soldering when a capacitor is mounted on the printed wiring board of FIG. 1;

FIG. 5 is a perspective view showing a part of a printed wiring board according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing a part of a printed wiring board according to a third embodiment of the present invention.

FIG. 7 is a perspective view showing a part of a conventional printed wiring board.

FIG. 8 is a diagram showing a state when cream solder is applied to the land of FIG. 7 and melted.

FIG. 9 is a diagram showing a state of soldering when a capacitor is mounted on the printed wiring board of FIG. 7;

[Explanation of symbols]

 10A, 10B, 10C Printed wiring board 11A, 11B, 11C Land 13 Board body 17-1, 17-2 Solder 17a Fillet 40, 41 Slit 42, 43, 44 Land part 45, 46 Landless part 47 Solder resist surface 50 to 53 Arrow indicating that solder is gathered 60, 61 Solder resist strip 62, 63, 64 Land 70, 71 Printing strip 72, 73, 74 Land

Claims (3)

[Claims] 1. A printed wiring board having a land used for soldering a component, wherein the land has a solder adhesion rejection area in which a molten solder does not adhere to a part of the land, and the remaining part is molten. A printed wiring board, wherein a land portion to which solder is applied is formed. 2. The solder attachment rejection region has a shape that is long in the direction in which the paired lands are arranged, and the land portion has a shape that is long in the direction in which the paired lands are arranged. The printed wiring board according to claim 1, wherein 3. A component soldering structure in which a surface mounting type component is configured by soldering its electrodes to the lands of the printed wiring board according to claim 1.