JPH04268792A - Method of mounting chip component - Google Patents

Abstract

PURPOSE:To provide a chip component mounting method where a chip component can be protected against a tomb stone phenomenon and prevented from getting out of position and floating. CONSTITUTION:Cream solder 6 is applied onto a connecting terminal 3 of a printed board 1, and a chip component 4 provided with electrodes 5 at its ends is placed thereon. Then, the connecting terminal 3 on the printed board 1 and the chip component 4 are coated with a separable heat-resistant resin film 7b, the resin film 7b is set by heating, and then the cream solder 6 is fused by heating to execute a soldering operation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting chip components, which connects the chip components to connecting terminals on a printed circuit board by soldering.

0002

[Prior Art] Conventionally, when mounting chip components such as chip resistors and chip capacitors on a printed circuit board, cream solder is first printed on the pads of the printed circuit board, and before the cream solder dries, a chip is placed on top of it. Place the parts. Next, the cream solder is melted by reflow, and the chip components are connected to the pads. In this way, chip components can be mounted on the printed circuit board.

0003

However, the chip component 14 has become smaller and smaller, with a length of 1.0 mm and a width of 0.5 mm. on the other hand,
There is a limit to the printing accuracy of printing methods, and a certain amount of printing misalignment may occur. Furthermore, there are limits to the control of the amount of solder during solder printing and solder reflow, resulting in variations in the amount of solder between both electrodes of the chip component. Therefore, as shown in FIG. 7, the chip component 14 having both electrodes 15 may be misaligned at the position of the cream solder 13 on the pad 12, or the end may be lifted, or in more extreme cases, as shown in FIG. There is a problem that a tombstone phenomenon occurs in which the chip component 14 stands up.

In order to solve this problem, as shown in FIGS. 9 and 10, an adhesive is applied between the pads 12 to form an adhesive layer 16.
An adhesive temporary fixing method is used to form and fix the chip component 14. However, in this case, as mentioned above, since the chip component 14 is extremely small, there is not enough space to form the adhesive layer 16, and the position of the adhesive applied may shift or the amount applied may be too large. Otherwise, the adhesive will stick to the pad 12, causing a defect. Therefore, there is a problem in that it is difficult to accurately apply an appropriate amount of adhesive to a small part. As a result, there is still a problem that it is not possible to prevent the chip component 14 from being misaligned or floating when it is mounted, and furthermore, the tombstone phenomenon cannot be prevented.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for mounting chip components that can prevent misalignment, floating, and tombstone phenomena during chip component mounting.

[0006]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a chip component having an electrode at an end is placed on a connecting terminal of a printed circuit board coated with cream solder, and then the cream solder is applied. In the method for mounting a chip component in which the chip component is soldered to the connection terminal by heating and melting the chip component, the connection terminal on the printed circuit board and the chip component are coated with a peelable heat-resistant resin coating, and then the heat-resistant resin coating is The gist of the present invention is a method for mounting chip components, which is characterized in that the cream solder is heated and cured, and then the cream solder is heated and melted to perform soldering.

[0007]

[Operation] First, a chip component having an electrode at the end is placed on a connecting terminal on a printed circuit board coated with cream solder. Next, these connection terminals and chip components are covered with a peelable heat-resistant resin film. Thereafter, the heat-resistant resin coating is cured by heating. Next, the chip component is mounted at a predetermined position of the connection terminal on the printed circuit board by heating and melting the cream solder and soldering the chip component to the connection terminal.

[0008]

[Embodiments] Examples embodying the present invention will be described below with reference to FIGS. 1 to 6. As shown in FIGS. 2 and 3, a pair of pads 3 as connecting terminals formed at the ends of a wiring pattern 2 are arranged on a printed circuit board 1 at positions facing each other with a constant interval. . On the other hand, a chip component 4 such as a chip resistor or a chip capacitor has a rectangular parallelepiped shape and has electrodes 5 at both ends thereof. Then, this chip component 4 is placed on both pads 3, so that the electrode 5 of the chip component 4 and both pads 3 can be connected.

Now, a method for mounting the chip component 4 onto the printed circuit board 1 will be explained. As shown in FIGS. 2 and 3, cream solder 6 is applied by screen printing onto both pads 3 of a printed circuit board 1 provided with a solder resist 10.
print. Then, before the cream solder 6 dries, the chip component 4 is placed so that the electrodes 5 of the chip component 4 are placed on both pads 3.

Next, as shown in FIG. 4, a peelable heat-resistant resin 7a is applied using a dispenser 8, which is a coating machine.
It flows down onto the pad 3, cream solder 6, and chip component 4 so as to entirely cover them. in this case,
It is necessary to flow down from directly above the pad 3 and the chip component 4 so that the position of the chip component 4 on the pad 3 does not shift. The removable heat-resistant resin 7a is a resin that can withstand heating during reflow of the cream solder 6 and can be easily peeled off. As this heat-resistant resin 7a, 75.0% vinyl resin derivative,
A resin composition consisting of 10.0% special liquid resin, 13.0% flame retardant agent, 0.8% polymerization inhibitor, 1.0% thixotropic agent, and 0.2% organic pigment (Asahi Chemical Research Institute Co., Ltd.) Product name: STRIP MASK #448T
) was used. This resin composition is a paste-like resin and has excellent workability during coating.

Next, in this state, the heat-resistant resin 7a is cured by heating at 130° C. for 10 minutes. If this heating temperature is low, the strength of the resin coating will decrease and it will become difficult to peel off. In this way, the heat-resistant resin film 7b is formed on the pad 3 and the chip component 4, as shown in FIGS. 1 and 5. Next, the cream solder 6 is melted by heating at 150 to 200[deg.] C. for several seconds by reflow. and,
As shown in FIG. 6, the electrode 5 of the chip component 4 is fixed to the pad 3 to electrically connect them. At this time, since the heat-resistant resin coating 7b has sufficient heat resistance, a constant shape is maintained. Thereafter, the heat-resistant resin coating 7b is peeled off if necessary. At this time, the heat-resistant resin coating 7b
has good releasability, so it can be easily peeled off from the chip component 4 and the like. In this way, the chip component 4 is mounted on the printed circuit board 1.

As described above, according to the mounting method of the chip component 4 of this embodiment, the chip component 4 is reliably fixed in a predetermined position on the pad 3 by the heat-resistant resin coating 7b, so that the cream solder is then applied. There is no risk that the chip component 4 will move from its position even if the chip component 6 is melted. Therefore, when the chip component 4 is mounted, the chip component 4 does not shift or float relative to the pad 3, and the tombstone phenomenon does not occur. In addition, since the heat-resistant resin coating 7b only needs to cover the entire mounting portion consisting of the chip component 4, cream solder 6, and pad 3, the accuracy of the position where the adhesive is applied, the amount of application, etc. It does not require any adjustment, and only rough accuracy is required to cover the mounting part.

Furthermore, since the heat-resistant resin coating 7b has good peelability, by peeling off the heat-resistant resin coating 7b, the chip component 4 can be easily exposed from the heat-resistant resin coating 7b, and other It does not interfere with the mounting of electronic components. The present invention is not limited to the above embodiments, and may be configured as follows, for example, without departing from the spirit of the invention.

That is, in the above embodiment, when the heat-resistant resin coating 7b is peeled off, a chlorine-based organic solvent such as trichloroethane or methylene chloride is used to remove the heat-resistant resin coating 7b.
It can also be removed by dissolving it.

[0015]

According to the method for mounting chip components of the present invention, it is possible to reliably prevent misalignment, floating, and even tombstone phenomena during the mounting of chip components.

[Brief explanation of the drawing]

FIG. 1 is a sectional view representing an embodiment of the present invention and showing a state in which a heat-resistant resin film is formed on a pad and a chip component.

FIG. 2 is a plan view showing a state in which a chip component is placed after cream solder is printed on a pad.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a cross-sectional view showing a state in which heat-resistant resin is flowing down from above the chip component.

FIG. 5 is a plan view showing a state where the chip components and the vicinity of the pads are coated with a heat-resistant resin film.

FIG. 6 is a cross-sectional view showing the state after chip components are mounted.

FIG. 7 is a diagram showing a conventional example, in which after printing cream solder on a pad, placing a chip component and reflowing,
FIG. 3 is a plan view showing a state in which the chip components are misaligned.

FIG. 8 is a cross-sectional view showing a state where a chip component has caused a tombstone phenomenon.

FIG. 9 is a plan view showing a state in which an adhesive layer is provided between both pads.

FIG. 10 is a cross-sectional view showing a state in which an adhesive layer is provided between both pads.

[Explanation of symbols]

1...Printed circuit board, 3...pad as a connection terminal, 4...
Chip parts, 6...Cream solder, 7b...Heat-resistant resin coating

Claims (1)

[Claims] Claim 1: An electrode (5) is placed at the end on the connection terminal (3) of the printed circuit board (1) coated with cream solder (6).
) in the mounting method of the chip component (4), which comprises placing the chip component (4) having the above-mentioned components, and then heating and melting the cream solder (6) to solder the chip component (4) to the connection terminal (3). , After coating the connection terminals (3) and chip components (4) on the printed circuit board (1) with a peelable heat-resistant resin film (7b), the heat-resistant resin film (7b)
A method for mounting chip components, characterized in that the cream solder (6) is heated and cured, and then the cream solder (6) is heated and melted to perform soldering.