JPH05121868A - Soldering package method of electronic part on printed substrate - Google Patents

Abstract

PURPOSE:To reduce generation of a side ball at a side of an electrode part by applying cream solder to a surface of a component pad making non- application parts of cream solder remain in two corner parts at an electronic component side among four corner parts of the component pad. CONSTITUTION:Punched holes 5, 6 in a mask plate 4 are provided with tilting corner-remaining parts 5a, 5b, 6a, 6b at parts corresponding to two corner parts at a side of an electronic component among four corner parts of each of component pads 2, 3. Cream solders 7, 8 are applied making non-application parts 7a, 7b, 8a, 8b of cream solder remain at two corner parts along at the side of the electronic component A among four corner parts of each component pads 2, 3. Thereby, generation of side ball of a side of an electrode part can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a structure in which connecting electrodes are formed on both left and right ends of a main body, such as a chip capacitor or a chip resistor, on a printed circuit board on which printed wiring is provided in advance. The present invention relates to a mounting method in which a chip-type electronic component is mounted by soldering.

[0002]

2. Description of the Related Art Conventionally, one method of mounting this type of chip type electronic component on a printed circuit board by soldering is as follows. First, as shown in FIG. In order to connect the two electrode parts A ₁ and A ₂ in the component A, the substantially rectangular component pads 2 and 3 having the width dimension W ₁ and the length dimension L ₁ are formed. As shown in FIGS. 7 and 8, after the mask plate 4 having the through holes 5 and 6 is superposed on the corresponding portions of the component pads 2 and 3, cream solder is applied to the surface of the mask plate 4. As a result, the component pads 2,
As shown in FIG. 9, cream solders 7 and 8 are applied to the entire surface of each of the Nos. 3 and 3, and then the electronic component A is applied to each of the cream solders 7 and 8 as shown in FIG. After mounting, the entire printed circuit board 1 is placed in a heating furnace and heated to a temperature not lower than the melting point of the solder, so that the electronic component A is soldered to the component pads 2 and 3.

In this soldering method,
Note Length L of each component pad 2 and 3 ₁The electronic components
Each electrode part A in A₁, A₂Greater than the length dimension L of
As a result, the respective component pads 2 and 3 become electronic parts.
Each electrode part A in product A₁, A₂I'm going to stick out more
Each of the holes in the mask plate 4
5 and 6 are rectangles of the same size as the component pads 2 and 3
Each of the component pads 2 and 3 is formed by forming a hole.
Apply cream solder 7,8 over the entire surface
I am trying.

[0004]

According to this conventional method, since the cream solders 7 and 8 are applied over the entire surfaces of the component pads 2 and 3 on the printed circuit board 1, the component pads 2 and 2 of the electronic component A are applied. When soldered to 3, the solder is applied to both electrode portions A ₁ and A ₂ of the electronic component A, as shown in FIG. Since it is possible to form the solder fillets 9 and 10 that bulge obliquely upward, there is an advantage that the reliability of soldering can be improved.

On the other hand, however, the amount of surplus solder increases, and this surplus solder adheres to the side surfaces of the electrode parts A ₁ and A ₂ in the electronic component A in a ball-like state from the side surfaces. Then, so-called solder side balls are generated. Therefore, not only the amount of cream solder used increases, but also when the plurality of electronic components A are mounted adjacent to each other, the solder side balls are connected to each other between adjacent electronic components A and short-circuit. So to avoid this,
It is necessary to widen the pitch interval P between the electronic components A, which leads to an increase in the size of the printed circuit board.

In order to suppress the generation of the side balls of the solder, the mask plate 4 is applied to each of the component pads 2 and 3 and the cream solder 7 and 8 is applied thereto. By making the size of each of the holes 5 and 6 in 4 smaller than that of the respective component pads 2 and 3,
As shown in FIG. 12, cream solder 7, 8 may be applied to a narrow area of the surface of each component pad 2, 3, but in this case, each solder fillet 9, 1 is formed.
The rising height of 0 becomes low, or the solder fillets 9 and 10 cannot be formed, so that soldering failure occurs.

According to the present invention, when the chip type electronic component as described above is soldered to a printed circuit board,
Provided is a soldering mounting method capable of reliably preventing generation of a side ball of solder on a side surface of an electrode part of the electronic component without causing a defective soldering of the electronic component to a printed circuit board. This is a technical issue.

[0008]

In order to achieve this technical object, the present invention comprises applying cream solder to the surface of a substantially rectangular component pad formed on a printed circuit board, and then providing the electrode section. In the soldering mounting method, the chip-type electronic component is placed so that the electrode part of the electronic component overlaps a part of the component pad and then heated to the melting point of the solder. When applying the cream solder to the surface of the pad, it was decided to apply the cream solder to the two corners on the electronic component side of the four corners of the component pad, leaving the non-painted portion of the cream solder. .

[0009]

[Operation] When applying cream solder to the surface of the component pad on the printed circuit board, the non-cream solder is applied to the two corners on the electronic component side out of the four corners on the component pad as described above. When the coating is performed leaving the coating portion, a sufficient amount of cream solder can be secured in the portion of the component pad protruding from the electrode portion of the electronic component, while Since the amount of cream solder in the portion where the electronic component overlaps the component pad can be reduced by the amount of the non-coated portion of the cream solder, when soldering with the cream solder, the amount of the cream solder is changed from the electronic component of the component pad. While the solder fillet can be reliably formed on the part protruding to the outside, on the side surface of the electrode part in the electronic component, It is possible to reliably reduce the occurrence of side balls due to excess solder.

[0010]

As described above, according to the present invention, under the condition that the reliability of soldering by the solder fillet is secured,
Since it is possible to reliably reduce the occurrence of side balls of solder, the amount of cream solder used can be reduced and the cost can be reduced, and when a plurality of electronic components are mounted side by side on a printed circuit board, There is an effect that the pitch interval between them can be narrowed to reduce the size of the printed board.

[0011]

Embodiments of the present invention will now be described with reference to the drawings (FIGS. 1 to 3).
Will be described. In the figure, reference numeral 1 indicates a printed circuit board. On the upper surface of the printed circuit board 1, two component pads 2 and 3 are formed for one chip-type electronic component A. The two component pads 2 and 3 are It has a substantially rectangular shape with a width dimension W ₁ and a length dimension L ₁ , and when the electronic component A is placed on this, a part of both component pads 2 and 3 protrudes from the electronic component A to the outside. It is configured.

Reference numeral 4 indicates a mask plate used when cream solder is applied to the surfaces of the component pads 2 and 3 on the printed circuit board 1, and the mask plate 4 includes the component pads 2 , 3 are formed in the rectangular shape of the same size as the component pads 2 and 3, so that the holes 5 and 6 are formed.
The cream solder 7, 8 is applied only to the portion inside 6.

In this case, the holes 5 and 6 in the mask plate 4 have portions corresponding to the two corners on the electronic component A side among the four corners of the component pads 2 and 3, respectively. In addition, the inclined corner remaining portions 5a, 5b, 6
By providing a and 6b, the cream solder 7, 8 can be formed.
Is applied to only the two corners on the electronic component A side out of the four corners of each of the component pads 2 and 3 so as to leave the non-coated portions 7a, 7b, 8a and 8b of the cream solder. To wear.

In this way, each of the component pads 2,
A sufficient amount of cream solder can be secured in a portion of the electronic component A that extends out of the electrode portions A ₁ and A ₂ of the electronic component A, while in the component pads 2 and 3 with respect to the relevant component pad. The amount of cream solder in the portion where the electronic component A overlaps is determined by
Since only 7b, 8a, 8b can be used, when soldering with the cream solder 7, 8, a solder fillet is surely formed on a portion of each component pad 2, 3 protruding from the electronic component A to the outside. The electrode parts A ₁ , A ₂ in the electronic component A
It is possible to reliably reduce the occurrence of solder side balls on the side surface of the.

According to the experiments conducted by the present inventors, the mask
Corner-remaining portions 5a, 5b, 6 of the holes 5, 6 in the plate 4
Width dimension of a and 6b with respect to component pads 2 and 3
Method S is the width W of the component pads 2 and 3₁Against
Each hole in the mask plate 4 is reduced to about one-third
Parts in corner remaining portions 5a, 5b, 6a, 6b of 5, 6
The length T of the pads 2 and 3 is the component pad.
Length dimension L in 2 and 3 ₁Can be about half
Preferably, in particular, the corner-remaining portions 5a, 5a,
The dimension S in 5b, 6a, 6b is the component pad 2, 3
Width W at ₁If it is close to half of, that is, before
The corner remaining portions 5a, 5b, 6a in the respective punched holes 5, 6
6b are continuous with each other as shown in FIG.
When the holes 5 and 6 are almost in the shape of a pentagon
Applied cream solder in each of these holes 5 and 6.
When lifting the mask plate 4 from the printed circuit board 1,
Part of the cream solder in the holes 5 and 6 is a mass.
Peel from the component pads 2 and 3 while attached to the black plate 4.
Cream solder on the surface of each component pad 2 and 3
As shown in Fig. 5, 7 and 8 are
Therefore, soldering failure occurs.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment according to the method of the present invention.

FIG. 2 is a perspective view when cream solder is applied to each component pad in the method of the present invention.

FIG. 3 is a perspective view when an electronic component is mounted in the method of the present invention.

FIG. 4 is a perspective view of a mask plate used before reaching the present invention.

FIG. 5 is a perspective view when cream solder is applied on the mask plate of FIG. 4;

FIG. 6 is a perspective view of a printed circuit board showing a conventional method.

FIG. 7 is a perspective view when a mask plate is overlaid on the upper surface of a printed circuit board by a conventional method.

FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG. 7.

FIG. 9 is a perspective view when cream solder is applied to each component pad in the conventional method.

FIG. 10 is a perspective view when an electronic component is mounted by a conventional method.

FIG. 11 is a vertical sectional front view of the soldered state.

FIG. 12 is a perspective view showing another conventional method.

[Explanation of Codes] A Chip-type electronic component A ₁ , A ₂ Electrode part 1 Printed circuit board 2, 3 Component pad 4 Mask plate 5, 6 Punch hole 5a, 5b, 6a, 6b Corners left in punch hole 7, 8 Cream Solder 7a, 7b, 8a, 8b Non-coated part of cream solder

Claims (1)

[Claims] 1. A chip-type electronic component provided with cream solder on the surface of a substantially rectangular component pad formed on a printed circuit board, and then the electrode portion of the electronic component is the component. In a soldering mounting method in which the pad is placed so that it overlaps with a part of the pad, and then the solder is heated to the melting point of solder, when cream solder is applied to the surface of the component pad, A method for soldering and mounting an electronic component on a printed circuit board, characterized in that two non-adhesive portions of cream solder are applied to two of the four corner portions on the electronic component side, leaving an uncoated portion.