JP2000156589A - Printed board mounted with electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an electronic part against electrostatic breakdown by coating the upper surface side of the electronic part with an aluminum foil connected electrically with the GND of a printed board and then coating the electronic part and the aluminum foil with silicon resin. SOLUTION: An electronic part 2 is coated entirely with an aluminum foil 4 which is applied tightly to the electronic part 2 at the intermediate part and to a printed board 1 at the opposite ends. End part of the aluminum foil 4 is connected electrically with the GND of the printed board 1. The electronic part 2 coated with the aluminum foil 4 is further coated with silicon resin 32. The electronic part 2 may generate static electricity due to various factors, e.g. mutual influence between circuit parts but since it is earthed to the GND of the printed board 1 through the aluminum foil 4, static electricity generated in the electronic part 2 can be grounded immediately and electrostatic breakdown thereof can be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the prevention of electrostatic breakdown of electronic components, and more particularly to a printed circuit board on which electronic components are mounted.

[0002]

2. Description of the Related Art A printed circuit board incorporated in various electric / electronic devices mounts various electronic components to form a circuit required for each device. Among electronic components mounted on a printed circuit board, there are electronic components having low electrostatic resistance, such as FETs and ICs. When handling such an electronic component having a weak resistance to static electricity, care must be taken so that the electronic component is not destroyed by the electrostatic spark.

For this reason, conventionally, as a measure for preventing electrostatic spark destruction, an antistatic pallet is used for transporting a printed circuit board during a manufacturing operation, a worker of a manufacturing line is grounded to a human body, or a floor of the manufacturing line is grounded. Measures such as laying an antistatic mat on the floor.

[0004]

However, none of the above measures can completely prevent electrostatic breakdown of electronic components, and all of these measures require careful handling of a printed circuit board on which electronic components are mounted. And the workability is inferior, requiring the attention of the worker.

Accordingly, the present invention proposes a printed circuit board on which electronic components are mounted so that the electronic components can be prevented from being destroyed by static electricity and can be easily handled by a worker on a production line.

[0006]

The printed circuit board on which the electronic component of the present invention is mounted has a lower surface side of the electronic component mounted on the printed circuit board and an upper surface side covered with aluminum foil. The end is electrically connected to the GND of the printed circuit board while covering the component, and the electronic component and the aluminum foil are covered with a silicon resin.

[0007]

Embodiments of the present invention will be described with reference to the drawings. The printed circuit board on which the electronic component of the present invention is mounted has the electronic component 2 mounted on a printed circuit board 1 on which a conductive foil is formed in advance. This electronic component 2 is FE
It is an electronic component having weak static resistance such as T or IC. The electronic component 2 is provided with four lead terminals 21 from both sides of a rectangular parallelepiped resin case, and these lead terminals 21 are electrically connected to the conductive foil of the printed circuit board 1 by soldering or the like.

Next, the lead terminals 21 provided on both sides of the electronic component 2 are each coated with a silicon resin 31. Thereafter, the entire electronic component 2 is covered with the aluminum foil 4. As shown in FIG. 2, the aluminum foil 4 is in close contact with the upper surface of the rectangular parallelepiped electronic component 2 in the middle portion, and is in close contact with the printed circuit board 1 in both end portions. Therefore, while the aluminum foil 4 has a height difference by the height of the electronic component 2,
The entire electronic component 2 is covered. The end of the aluminum foil 4 is electrically connected to GND of the printed circuit board 1. As a method of adhering the aluminum foil 4, an adhesive tape having an adhesive property may be used, or an adhesive or the like may be used. The electrical connection to the printed circuit board 1 is made by a conductive adhesive. The aluminum foil 4 and the lead terminals 21 of the electronic component 2 are insulated by the silicon resin 31.

Then, the electronic component 2 covered with the aluminum foil 4
Is covered with the silicon resin 32 from above the aluminum foil 4. The silicon resin 32 has a role of insulating so as to prevent the conductive aluminum foil 4 from being exposed to the outside and a role of preventing peeling of the aluminum foil 4.

The electronic component 2 may generate static electricity due to various factors such as the influence between circuit components and the like, but since the electronic component 2 is grounded to the GND of the printed circuit board 1 by the aluminum foil 4, The static electricity generated in the electronic component 2 is immediately grounded to reduce the possibility that the electronic component 2 is broken by the static electricity.

By covering the electronic component 2 with the aluminum foil 4, the electronic component 2 is not destroyed even if a spark voltage is applied which has been destroyed in the conventional electronic component 2 not provided with the aluminum foil 4. That has been confirmed.

That is, the results of a test performed using the test circuit diagram shown in FIG. 3 will be described below. In this test, a printed circuit board used for a lithium ion battery pack battery is used. A lithium ion battery pack battery has a built-in printed circuit board on which a protection circuit for controlling charging and discharging is mounted. The protection circuit uses an FET that controls switching of a charging current and a discharging current.

In this test circuit diagram, a spark tester is brought into contact with the gate terminal of the FET, and the voltage at which the FET is destroyed is measured while gradually increasing or decreasing the applied voltage from 1 kV. The atmosphere during the test was a temperature of 25 ° C. and a humidity of 65%. Further, the VGS-ID characteristics of the FET were measured.

As a result, the conventional FET without aluminum foil or silicon resin was broken at +5 V or -5 V, whereas the FET according to the present invention with aluminum foil or silicon resin was broken at +15 V or No destruction was observed up to about -15 V, confirming the effect of the present invention.

[0015]

According to the present invention, static electricity generated in an electronic component is grounded by electrically connecting an aluminum foil covering the electronic component to GND of a printed circuit board. The silicon resin applied thereon insulates the aluminum foil and prevents the aluminum foil from peeling or being damaged. Therefore, the present invention can prevent electrostatic breakdown of electronic components mounted on a printed circuit board and obtain a printed circuit board mounted with electronic components that can be easily handled by a production line worker. it can.

As a result, for example, the present invention can be used for a printed circuit board incorporated in a battery pack of a lithium ion battery. In this case, the reliability of the battery pack can be improved by preventing the electrostatic discharge of the FET that switches the charging current and the discharging current. Furthermore, even if the electrolyte of the lithium ion battery leaks out and adheres to the FET mounted on the printed circuit board, since it is coated with the silicon resin according to the present invention, short-circuiting due to the electrolyte or an element etc. Can be prevented, and can be used extremely safely.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a printed circuit board on which electronic components according to the present invention are mounted.

FIG. 2 is a sectional view of a main part in FIG.

FIG. 3 is a test circuit diagram

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Electronic component 21 Lead terminal 31 Silicon resin 32 Silicon resin 4 Aluminum foil

Claims (1)

[Claims] 1. A lower surface of an electronic component is mounted on a printed circuit board, and an upper surface of the electronic component is covered with aluminum foil, and the aluminum foil is electrically connected to GND of the printed circuit board while covering the electronic component. A printed circuit board on which electronic components are mounted, wherein the electronic components and the aluminum foil are covered with a silicone resin.