JPH05337396A - Metal powder removing device - Google Patents

Abstract

PURPOSE:To obtain a metal powder removing device sucking and removing the magnetic metal powder mixed with insulating varnish in a highly efficient manner. CONSTITUTION:A trap main body 11 is incorporated on the way of piping 10 and the insulating varnish flowing through the trap main body 11 is stirred while the passage thereof is changed by weir plates 14 and the metal powder mixed with the insulating varnish is attracted by the magnetic bodies 12 arranged to the under surface of the trap main body 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal powder removing device capable of sucking and removing magnetic metal powder mixed in an insulating varnish with high efficiency.

[0002]

2. Description of the Related Art A prepreg, which is a base material for a copper-clad laminated board or a multilayer printed wiring board, is manufactured by impregnating an insulating varnish into a glass cloth and drying it. Since this prepreg is used as an insulating base material such as a copper-clad laminate or a multilayer printed wiring board, it is necessary to prevent metal powder that may cause dielectric breakdown from entering the insulating varnish.

However, since the insulating varnish is pressure-fed through the pipe by using a pressure pump such as a gear pump, abrasion powder from the pressure pump or valves or metal powder contained in the constituent material of the insulating varnish is mixed. There is. Therefore, it is necessary to provide a device for removing metal powder that causes dielectric breakdown in the pipe for pumping the insulating varnish.

Next, a conventional metal powder removing device will be described. The structure shown in FIG. 3 has a configuration in which a tubular metal powder removing trap body 2 is installed sideways in the middle of the pipe 1, and the trap body 2 has an O-ring 3 on its upper surface side.
The magnetic body 4 is attached via. A baffle plate 5 is hung from the upper surface side of the trap body 2.

FIG. 4 shows a structure in which a tubular metal powder removing trap body 6 is installed upright in the middle of the pipe 1, and the cylindrical trap body 6 has a structure shown in FIG. As also shown in FIG. 1, magnet rods 7, which are magnetic bodies for adsorbing the metal powder, are arranged in the vertical direction with a predetermined space therebetween.

[0006]

By the way, the viscosity of the insulating varnish is as high as 0.1 to 1,000 Pa.s, and the metal powder having a diameter of 0.01 to 0.1 mm mixed in the insulating varnish has a magnetic force. To be sucked by and move 20 mm 1
It takes 0 to 20 seconds. Therefore, in order to adsorb the metal powder with high efficiency and remove the metal powder from the insulating varnish by suction, the flow of the insulating varnish is slowed down, the flow layer of the insulating varnish is thinned, and the contact time with the magnetic material is lengthened. Also, it is necessary to increase the contact area.

However, the above-described conventional metal powder removing device has the drawback that the contact time between the insulating varnish and the magnetic bodies 5, 7 in the trap bodies 2, 6 is short and the contact area is small. .. Therefore, the removal rate of the metal powder in the insulating varnish is as low as 30 to 60%, and the metal powder is mixed into the prepreg coated with the insulating varnish, which often causes defects in the copper-clad laminate and the multilayer printed wiring board. There is.

The present invention has been made in view of such circumstances, and an object of the present invention is to remove metal powder mixed in the insulating varnish with high efficiency. The purpose is to provide a device.

[0009]

In order to achieve such an object, the present invention provides a trap body which is incorporated in the middle of a pipe for pumping an insulating varnish and which circulates the insulating varnish.
A magnetic body that is arranged over the entire lower surface of the trap body and that attracts the metal powder mixed in the insulating varnish,
It is characterized in that it is installed perpendicularly to the flow direction of the insulating varnish in the trap body, regulates the thickness of the flow layer of the insulating varnish, and has a weir plate that stirs while changing the flowing direction of the insulating varnish. is there.

[0010]

[Operation] The metal powder on the top of the insulating varnish is moved to the magnetic side within the minimum time of flowing on the magnetic body due to the difference in gravity and potential energy, and is installed perpendicular to the flow direction of the insulating varnish. The flow direction is changed by the dammed cuffs, and the insulating varnish is accelerated to cause agitation, so that the metal powder is efficiently collected in the magnetic body.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory cross-sectional view showing a metal powder removing device according to the present invention along a flow path, and a trap body 11 for removing metal powder is attached with a pressure pump (not shown) such as a gear pump. It is incorporated between the pipes 10 and 10. Although not shown, the trap body 11 flows an insulating varnish while utilizing gravity and potential energy difference. Of course, in the case of pressure feeding, it is necessary to provide a lid on the upper part of the trap body 11 to withstand the internal pressure.

As described above, the viscosity of the insulating varnish is 0.
It is as high as 1 to 1,000 Pa · s, and it takes 10 to 20 seconds for the metal powder (diameter 0.01 to 0.1 mm) in the insulating varnish to move 20 mm due to the attraction of the magnet. for that reason,
The trap body 11 needs to slow the flow of the insulating varnish and thin the flow layer of the insulating varnish. In practice, the flow of the insulating varnish is always 20 mm or less, and the contact time with the magnetic body 12 (magnetic field) is 20 seconds or more. Secure and set so that a large amount of insulating varnish can be processed.

The area of the magnetic body 12, which is determined from the viscosity and flow velocity of the insulating varnish, is arranged over the entire lower surface of the trap body 11, and the arrangement is continuous so that the magnetic field is not cut off. It should be noted that the stronger the magnetic force is, the more expensive it is.
It must be T or higher, preferably 0.1 T or higher.
Further, the cover plate (SUS plate) 13 of the magnetic body 12 needs to be as thin as possible.

Further, the trap body 11 is provided with a weir plate 14 perpendicularly to the flow direction of the insulating varnish so that the trap varnish 11 can be stirred while flowing the insulating varnish.
Change the flow direction of the insulating varnish. Also, the trap body 1
The corner portion of the side plate 15 of No. 1 is suitable for removing the metal powder when it is provided with a curvature, and the curvature may be such that the fingertip is in close contact (see FIG. 2). The height of the weir plate 14 is set to be equal to or less than the thickness of the flow layer of the insulating varnish calculated from the flow velocity and the flow rate. If the insulating varnish flows over the height of the weir 14, the calculated time for contact with the magnetic body 12 cannot be kept.
Therefore, the height of the insulating varnish is regulated so that the flow of the insulating varnish is always less than or equal to the calculated value and that the flow can be determined at a glance.
It should be noted that two or more cuffs 14 are required for height monitoring.

Next, the results will be described below together with specific examples. The trap body 11 having a width of 300 mm and a length of 1500 mm is formed, and the height of the weir 14 is 10 mm.
No. 4 was installed in three places, and magnets having a magnetic force of 0.15 T were arranged. Then, the viscosity of 6 Pa in the trap body 11
s of insulating varnish was poured. At this time, the collection rate of the metal powder having a diameter of 5 μm or more was 99.5%.

[0016]

As described above, according to the present invention,
Metal powder mixed in highly viscous insulating varnish can be removed by suction with high efficiency, and a prepreg containing no metal powder can be produced, so copper-clad laminates and multilayer printed wiring boards, etc. It is possible to reduce the defect occurrence rate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a metal powder removing device according to the present invention along a flow path.

FIG. 2 is a cross-sectional view showing a side surface side of the device shown in FIG.

FIG. 3 is a cross-sectional view showing a conventional metal powder removing device.

FIG. 4 is a cross-sectional view showing another example of a conventional metal powder removing device.

5 is a cross-sectional view showing a plane side of the device shown in FIG.

[Explanation of symbols]

 10 Piping 11 Trap Main Body 12 Magnetic Material 13 Cover Body 14 Weir Board

Front page continued (72) Inventor Tsuyoshi Arai 1500 Ogawa, Shimodate, Ibaraki Hitachi, Ltd. Shimodate factory (72) Inventor Kei Takahashi 1500, Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd. Shimodate factory

Claims (1)

[Claims] 1. A trap main body, which is incorporated in the middle of a pipe for pumping an insulating varnish, and which circulates the insulating varnish, and a magnetic metal powder mixed in the insulating varnish, which is arranged over the entire lower surface of the trap main body. And a dam that is installed perpendicular to the flow direction of the insulating varnish in the trap body, regulates the thickness of the flow layer of the insulating varnish, and stirs while changing the flowing direction of the insulating varnish. Characteristic metal powder removal device.