JPH07321455A - Electronic parts mounting method - Google Patents

Abstract

PURPOSE:To provide a method for mounting electronic parts where an improved wire bonding property can be achieved without requiring a washing process in the surface-mounting technology using the mold chip advance-mounting method. CONSTITUTION:The title method is provided with a step for printing solder on a printed circuit board, a step for applying an adhesive for tentatively locking a protection sheet for protecting a COB-mounting part, a step for mounting a mold chip onto the solder, a step for tentatively locking the protection sheet with an adhesive, a step for hardening solder and fixing the mold chip onto the printed circuit board, a step for peeling the protection sheet, a step for mounting and fixing a bare chip to the COB-mounting part, and a step for performing resin-sealing of the bare chip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting method for mounting an electronic component on a printed circuit board, and more particularly to a molded chip when using both molded chip component mounting and COB mounting on one printed circuit board. The present invention relates to an electronic component mounting method called a tipping method.

[0002]

2. Description of the Related Art Conventionally, through-hole printed wiring technology and surface mounting technology (Surface Mounmt Technology: SM) have been used as printed wiring technology for mounting electronic components on a printed circuit board.
There is T). The former is to open a through hole in the printed circuit board and solder the legs of electronic parts to it.
The latter is to solder an electronic component directly to a copper conductor on the surface of a printed circuit board. In surface mounting technology, mold chip component mounting in which a mold chip component is mounted on a printed circuit board and COB (Chip On Board) mounting in which a bare chip is directly mounted on a printed circuit board are generally used. That is, in the mounting of the molded chip component, as shown in FIGS. 12 and 13, after mounting the molded chip component 7 on the printed board 1, the solder 5 is cured and fixed. In addition, COB mounting, as shown in FIG. 12 and FIG.
This is a method in which the bare chip 11 is mounted on the printed board 1 and fixed, then electrically connected by wire bonding 12 and resin-sealed by a coating member 13.

When the mold chip component mounting and the COB mounting are used together on one printed circuit board, there are two methods depending on which is to be carried out first. With the mold chip post-mounting method, in which the COB mounting is performed first and then the mold chip components are mounted, the COB mounting is performed directly on the delivered printed circuit board, so wire bonding is good and stable quality is obtained. Since the convex portion is formed on the printed circuit board, it is difficult to perform solder printing when mounting the mold chip component, and productivity is deteriorated. On the other hand, in the mold chip pre-mounting method in which the mold chip parts are mounted first and then the COB is mounted, the mold chip parts are mounted first, so that the solder can be processed by screen printing and high productivity can be achieved. Obtainable.

[0004]

In the case of this mold chip pre-mounting method, the heat contained in the mold chip parts causes the flux contained in the solder on the printed circuit board surface to scatter, which affects the wire bondability in COB mounting. give. For this reason, after mounting the molded chip component, in order to remove foreign matters such as dust and solder flux on the printed circuit board, ultrasonic cleaning is performed with a cleaning liquid such as CFC, and then COB mounting is performed. However, such a method not only requires control of the cleaning liquid that affects the wire bondability in COB mounting, but liquids such as CFCs are regulated in terms of pollution, and cleaning equipment and work are also required. Some methods are expensive in cost.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to achieve good wire bondability without requiring a cleaning step in the surface mounting technique using the mold chip pre-installation method. An object of the present invention is to provide an electronic component mounting method obtained.

[0006]

In order to solve such a problem, in the electronic component mounting method according to claim 1, the step of printing solder on the printed circuit board and the protective sheet for protecting the COB mounting portion are temporarily fixed. For applying adhesive for mounting, mounting mold chip on solder, temporarily fixing protective sheet with adhesive, curing solder to fix mold chip on printed circuit board, peeling protective sheet The method includes a step of mounting, fixing and mounting a bare chip on a COB mounting portion, connecting the bare chip to a printed board by wire bonding, and sealing the bare chip with a resin.

[0007]

According to the method of claim 1, the COB mounting portion is protected by the protective sheet at the time of mounting the molded chip component for hardening the solder and fixing the molded chip on the printed circuit board. Since foreign matter such as flux does not adhere and is kept clean, the wire bondability when connecting the bare chip to the printed circuit board is improved, and good electrical connection can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a flowchart of an electronic component mounting method, and FIGS. 2 to 10 are perspective views showing a state in which an electronic component is mounted at each step.

Reference numeral 1 denotes a printed circuit board, which has a COB mounting portion 2 and a molded chip component mounting portion 3 on a surface mounting portion 1a for mounting electronic components. This COB mounting unit 2
Although not shown in the drawing, a conductor pattern is drawn on the surface mounting portion 1a although it is on the end portion 1b of the surface mounting portion 1a and the other portion is the molded chip component mounting portion 3. Reference numeral 4 is a through-hole for peeling a protective sheet, which will be described later, and is provided in the vicinity of the COB mounting portion 2.

The sequence of the flow chart shown in FIG. 1 is as follows: solder screen printing as the first step, application of adhesive for temporary protection sheet protection as the second step, mounting of mold chips as the third step, protection as the fourth step. Temporary fixing of the sheet, solder hardening as the fifth step, peeling of the protective sheet as the sixth step, bare chip mounting as the seventh step, wire bonding as the eighth step, and resin sealing as the ninth step are performed for component mounting. The state of each step will be described below with reference to FIGS.
It will be described based on.

FIG. 2 shows the state of the first step in the flow chart, showing a state in which the solder 5 is screen-printed on the conductor portion of the portion for electrically connecting the mold chip component of the mold chip component mounting portion 3. ing. This solder 5 is creamy and uses RMA (Rosin Mild Active) type, which has less flux components.

FIG. 3 shows a state of the second step in the flow chart, and shows a state in which an adhesive 6 for temporarily fixing a protective sheet described later is applied. The adhesive 6 is a thermosetting resin and is applied in a small amount in the vicinity of the through hole 4 and on the opposite side of the COB mounting portion 2 with respect to the through hole 4.

FIG. 4 shows the state of the third step in the flow chart, and shows the state in which the molded chip component 7 is mounted on the solder 5 printed in the first step. Mounting of the mold chip component 7 is sequentially performed by a dedicated mounter in accordance with a program produced in advance. The molded chip part 7 includes various electronic parts such as resistors and capacitors.

FIG. 5 shows the state of the fourth step in the flow chart, in which the protective sheet 8 is attached with an adhesive.
The state is shown in which the COB mounting portion 2 is covered by temporarily fixing with. The protective sheet 8 is made of metal such as SUS having a thickness of about 0.1 mm, has a planar shape that completely covers the COB mounting portion 2, and is fixed by being closely attached onto the COB mounting portion 2. To do. This prevents the flux of the solder 5 from adhering to the COB mounting part 2 and reduces CO
It also suppresses the oxidation of the gold plating pattern (not shown) of the B mounting portion 2. FIG. 11 is a perspective view of the protective sheet feeding device 9 for the protective sheet 8, which shows the feeding air feeder 9
After the continuous hoop-shaped protective sheet 8 sent by a is cut by the cutting press 9b, it is carried on the printed board 1 by the general-purpose mounter head 9c.

FIG. 6 shows a state of the fifth step in the flow chart, and shows a state in which the solder 5 is cured and the mold chip component 7 is fixed on the printed board 1. It is desirable to cure the solder 5 in a nitrogen atmosphere.

FIG. 7 shows the state of the sixth step in the flow chart, and shows the state in which the protective sheet 8 has been peeled off. The protective sheet 8 is peeled off by pushing up the push-up bar 10 from the lower surface of the printed circuit board 1 through the through hole 4 to peel off the protective sheet 8 by the lever principle. The peeled protective sheet 8 is removed and reused as the case may be.

FIG. 8 shows a state of the seventh step in the flowchart, and shows a state in which the bare chip 11 is mounted and fixed on the COB mounting portion 2. The bare chip 11 is mounted by a die bonder.

FIG. 9 shows a state of the eighth step in the flow chart, and shows a state in which the bare chip 11 is electrically connected to the gold plating pattern of the printed board 1 by the wire bonding 12.

FIG. 10 shows a state of the ninth step in the flowchart, and shows a state in which the bare chip 11 is resin-sealed. In this resin encapsulation, the coating member 13 is discharged so as to cover the bare chip 11, and is cured and cured. This prevents the wire bonding 12 from being damaged.

By using the above method, in the mold chip pre-attachment method, by covering the COB mounting portion 2 with the protective sheet 8 at the time of mounting the mold chip,
Since the COB mounting unit 2 is kept clean, the COB mounting unit 2
After mounting the mold chip parts, make sure that the printed circuit board 1 does not get contaminated with foreign matter such as dust or solder flux.
Eliminates the need for cleaning.

In the embodiment, the electronic component mounting method has been described in the order as shown in the flowchart of FIG. 1, but the present invention is not limited to this. For example, the third step The order of the fourth step may be reversed, as long as the COB mounting portion is protected during the solder hardening in the fifth step when mounting the molded chip component.

[0022]

According to the electronic component mounting method of the first aspect of the present invention, the COB mounting portion is protected by the protective sheet at the time of mounting the molded chip component in which the solder is hardened and the molded chip is fixed on the printed board. Since the parts are kept clean without foreign matter such as solder flux, the wire bondability when connecting the bare chip to the printed circuit board is improved, and good electrical connection can be obtained, so that the quality can be improved. , Productivity is improved.

[Brief description of drawings]

FIG. 1 is a flowchart of an electronic component mounting method showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the state of the first step.

FIG. 3 is a perspective view showing a state of the second step.

FIG. 4 is a perspective view showing a state of a third step thereof.

FIG. 5 is a perspective view showing the state of the fourth step.

FIG. 6 is a perspective view showing a state of a fifth step thereof.

FIG. 7 is a perspective view showing a state of a sixth step thereof.

FIG. 8 is a perspective view showing the state of the seventh step.

FIG. 9 is a perspective view showing a state of the eighth step.

FIG. 10 is a perspective view showing a state of the ninth step.

FIG. 11 is a perspective view of the protective sheet supply device.

FIG. 12 is a top view showing a conventional example of the present invention when an electronic component is mounted.

FIG. 13 is a cross-sectional view when mounting the electronic component.

[Explanation of symbols]

 1 Printed circuit board 2 COB mounting part 3 Molded chip component mounting part 5 Solder 6 Adhesive 7 Molded chip component 8 Protective sheet 11 Bare chip 12 Wire bonding 13 Coating member

Claims (1)

[Claims] 1. A method of printing solder on a printed circuit board, a step of applying an adhesive for temporarily fixing a protective sheet for protecting a COB mounting portion, a step of mounting a mold chip on the solder, and a protective sheet. Temporarily fixing with adhesive, fixing the mold chip on the printed circuit board by hardening the solder, peeling the protective sheet, mounting and fixing the bare chip on the COB mounting part, wire bonding the bare chip to the printed circuit board An electronic component mounting method including a step of connecting to a semiconductor chip and a step of sealing a bare chip with resin.