JPH04268793A - 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, adhesive agent is printed on a heat-resistant film 9 to farm a releasable adhesive agent layer 7, the heat-resistant, film 9 is disposed an the chip component 4 making the adhesive agent layer 7 cover the chip component 4 and the connecting terminal 3, the adhesive agent of the adhesive agent layer 7 is hardened by heating, and the cream solder 6 is fused by heating to carry out 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 connection 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, chip components have become smaller and smaller, with a length of 1.0 mm and a width of 0.0 mm.
They are becoming as small as 5mm. On the other hand, there is a limit to the printing accuracy of the printing method, and a certain amount of printing misalignment may occur. Additionally, there are limits to controlling the amount of solder during solder printing and solder reflow.
Variations occur in the amount of solder between both electrodes of the chip component. As a result, 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 in 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 temporary fixing method is used in which an adhesive is applied between the pads 12 to form an adhesive layer 16 and the chip component 14 is fixed. ing. However, in this case, since the chip component 14 is extremely small as described above, 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. Then, pad 1
2. Adhesive will stick to the surface and cause defects. 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 a method for mounting chip components in which the chip component is soldered to the connection terminal by heating and melting, an adhesive is printed on a heat-resistant film to form a removable adhesive layer, and this heat-resistant film is bonded to the adhesive. After arranging the layer side on the chip component so as to cover the chip component and the connection terminal, the adhesive forming the adhesive layer is cured by heating, and then the cream solder is heated and melted to perform soldering. The gist is the method.

[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. On the other hand, a releasable adhesive layer is formed by printing a liquid adhesive on the heat-resistant film. This heat-resistant film is placed on the chip component so that the adhesive layer side covers the chip component and the connection terminal. Thereafter, the adhesive forming the adhesive layer is heated and cured. 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 chip components onto the printed circuit board 1 will be explained. As shown in Figures 2 and 3, cream solder 6 is applied on both pads 3 by screen printing.
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. On the other hand, as shown in FIG. 4, using a heat-resistant polyimide film 9,
A liquid adhesive is printed on this film 9 by a screen printing method to form a peelable adhesive layer 7. The above-mentioned liquid adhesive is a resin that can withstand the heat during reflow of the cream solder 6, and is an adhesive that can be easily peeled off after hardening. As this liquid adhesive, vinyl resin derivative 75
．． 0%, special liquid resin 10.0%, flame retardant agent 13.0
%, polymerization inhibitor 0.8%, thixotropic agent 1.0
%, organic pigment 0.2% (trade name: STRIP MASK, manufactured by Asahi Chemical Research Institute Co., Ltd.)
#448T) was used. This liquid adhesive is a resin with high viscosity and has excellent workability during printing.

[0010] The heat-resistant film 9 is
It is necessary that it is made of a resin that can withstand heating during reflow of the cream solder 6. As the film 9, in addition to the polyimide film described above, a film made of a fluororesin such as polytetrafluoroethylene (so-called Teflon), a silicone resin, or the like may be used.

Next, as shown in FIGS. 1 and 5, the film 9 is placed on the chip component 4 and the pad 3 with the adhesive layer 7 of the film 9 facing the chip component 4 before the adhesive is cured. And 1
The adhesive is cured by heating at 30° C. for 10 minutes. If this heating temperature is low, the strength of the adhesive layer 7 will decrease, making it difficult to peel off. By curing the adhesive by heating, a film 9 having an adhesive layer 7 can be formed on the pad 3 and the chip component 4.

[0012] Next, by reflow, the
℃ for several seconds to melt the cream solder 6. Then, as shown in FIG. 6, the electrodes 5 of the chip component 4 are fixed to the pads 3 to electrically connect them. Thereafter, the film 9 having the adhesive layer 7 is peeled off. In this way, the chip component 4 is mounted on the printed circuit board 1.

As described above, according to the method for mounting the chip component 4 of this embodiment, the chip component 4 is reliably fixed in a predetermined position on the pad 3 by the film 9 having the peelable adhesive layer 7. Therefore, even if the cream solder 6 is melted afterwards, there is no risk that the chip component 4 will move from its position. 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 above-mentioned film only needs to cover the entire mounting section consisting of the chip component 4, cream solder 6, and pad 3,
Unlike the adhesive temporary fixing method, it is not necessary to adjust the accuracy of the position where adhesive is applied and the amount of adhesive applied, and the accuracy for covering the mounting portion can be rough.

[0014] By processing the film 9 to match the shape of the chip parts to be covered and forming adhesive layers at necessary locations by screen printing, more chip parts can be covered. Furthermore, since the adhesive layer 7 of the film 9 has good releasability, by peeling off the film 9 having the adhesive layer 7, the chip component 4 can be easily exposed from the film 9, and other electronic It does not interfere with component mounting.

The present invention is not limited to the above-mentioned embodiments, but may be configured as follows without departing from the spirit of the invention. That is, in the above embodiment, when peeling the adhesive layer 7 of the film 9 from the electronic component 4, etc., the adhesive layer 7 is removed by dissolving it using a chlorine-based organic solvent such as trichloroethane or methylene chloride. You can also do that.

[0016]

According to the method for mounting chip components of the present invention, it is possible to achieve the excellent effect of preventing misalignment, floating, and tombstone phenomena during mounting of chip components.

[Brief explanation of the drawing]

FIG. 1 is a sectional view representing an embodiment of the present invention, showing a state in which a film having an adhesive layer is coated on a pad and a chip component.

FIG. 2 is a plan view showing a state in which a chip component is placed after printing cream solder 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 a film having an adhesive layer is placed above the chip component.

FIG. 5 is a plan view showing a state in which the chip component and the vicinity of the pad are covered with a film having an adhesive layer.

FIG. 6 is a cross-sectional view showing a state after mounting the chip component.

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, 5... Electrode, 6... Cream solder, 7... Adhesive layer, 9... Heat resistant film

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). , an adhesive is printed on the heat-resistant film (9) to form a removable adhesive layer (7), and this heat-resistant film (9) is attached to the chip component (4) with the adhesive layer (7) side facing the chip component (4).
) and the connection terminals (3), the adhesive forming the adhesive layer (7) is heated and cured, and then the cream solder (6) is heated and melted. A method for mounting chip components, which is characterized by soldering.