JPS61121490A - Electronic component mounting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mounting device for a printed circuit board on which electronic components are wired.

Conventional Structures and Problems There are broadly two methods for attaching electronic components, particularly chip components, to soldering lands of a wired circuit section and making solder connections using a wired circuit board. One is to use the non-soldered parts of the chip components on the board surface between the soldering lands to be fixed to the printed circuit board using adhesive, and then use a solder jet bath to connect the electrodes of the chip components to the printed circuit board. The other method is the flow soldering method, in which soldering is performed on the soldering land of the printed circuit board.The other method is to print or apply cream solder to the soldering land of the wiring circuit board, then apply it with a dispenser, attach the chip parts, and then apply the cream solder to the soldering land of the circuit board. A reflow soldering method is used in which the adhesiveness of the solder is used to temporarily hold the solder at a temperature higher than that at which the solder melts, or to solder using a flow bath.

The present invention relates to the latter method, and the conventional example is shown in FIGS.
It is shown in Figure 4.

FIG. 1 is a diagram showing an example of a wired circuit portion 2 and a soldering land 3 formed on a wired circuit board 1, and a hatched portion 4 indicates a solder resist overcoated on the wired circuit. FIG. 2 shows a state in which cream solder 5 is applied to the soldering land, and FIG. 3 shows a state in which chip components are attached.

In FIG. 3, the cream solder 5 applied to the soldering land 3 is formed by attaching the chip component 6 to the bottom surface of the chip, which is generated due to the thickness of the electrode of the chip component 6 and the thickness of the soldering land 3. It is in a state where it is swept away into the space C on the upper surface of the printed circuit board 1.

When soldered in one reflow tank under the above conditions, the fourth
As shown in the figure, the molten solder does not fully return to the soldering rad 3 and a ball-shaped solder remains on the bottom surface of the chip component 6, causing a short circuit between the electrodes of the chip component 6 due to the solder ball 7. was there.

OBJECTS OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to improve the soldering quality in soldering chip components to printed circuit boards based on the reflow one-way method.

Structure of the Invention In order to achieve all of these objects, the present invention provides a dimension that is higher than the height to the bottom surface of the chip component placed on the substrate surface between the soldering lands to which the electrode portion of the chip component is soldered. This structure prevents the formation of solder balls between the chip electrodes. :It's something I lost.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is a sectional view based on an embodiment of the present invention corresponding to FIG. 2 of the conventional example, and FIG. 6 is a sectional view of FIG. 5 with all chip components attached.

In FIG. 5, the shaded area shows the solder resist 8 which is also overcoated by printing between the soldering lands.
The thickness is such that no space is created between the lower surface of the mounted chip component 6 and the upper surface of the printed circuit board 1, that is, the thickness is larger than the dimension C shown in FIG.

When the chip component 6 gold is mounted on the printed circuit board 1 shown in FIG. 6, the cream solder 5 applied as shown in FIG. However, since the upper surface of the solder resist 8 comes into contact with the lower surface of the tip component 6, the solder resist 8
The flow of cream solder 6 stops at end face 9 of .

By performing soldering in one reflow bath in the above state, it is possible to prevent short circuits caused by solder balls between the electrodes of the chip component 6 on the lower surface of the chip component 6.

Effects of the Invention As described above, according to the present invention, in the cream solder applied to the soldering land portion of a printed circuit board, even if the amount of application and the application position with respect to the soldering land occur more than before, the soldering land can be easily maintained. The solder resist in between prevents cream solder from flowing to the bottom surface of the chip component, and also provides margin for work accuracy, preventing short circuits between the electrodes of the chip component and improving soldering quality. be able to.

In addition, the number of man-hours required for corrections such as short circuits between electrodes of chip components, check inspections, and corrections in the event of short circuits is also reduced, making it possible to reduce the number of man-hours.

In addition, as another embodiment of the present invention, for example, using an alumina base material, a wiring circuit part and a soldering land are formed on the alumina base material by printing and firing silver or silver alloy or other metal paste, Even in aluminum wiring boards where the circuit parts other than the soldering lands are coated with glass, alumina wiring can be achieved by applying glass coating on the surface of the alumina base material between the soldering lands for soldering the electrodes of chip components. The same effect can be achieved on the substrate as well.

[Brief explanation of drawings]

Figure 1 is a plan view showing a printed circuit board in a conventional electronic component mounting device, Figure 2 is a cross-sectional view of the same board, and Figure 3 is a cross-section showing a state in which chip components are mounted on the board in Figure 2. 4 is a cross-sectional view showing a state in which the IJ-mu solder shown in FIG. 3 has been hardened. FIG. 6
The figure is a sectional view showing a state in which chip components are attached to the same board. 1... Wired circuit board, 3... Soldering land, 4°8... Solder resist, 5... Cream solder, 6... Chip parts. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4 Figure 5

Claims (1)

[Claims] An electronic component characterized in that an insulating layer having a dimension higher than the height to the bottom surface of the chip component placed on the substrate is formed on the substrate surface between the soldering lands to which the electrode portion of the chip component is soldered. mounting device.