JPH08250874A - Vibration damper for printed board - Google Patents

Abstract

PURPOSE: To prevent reworking at the time of modification from being extremely difficult or optic performance of an optic system from deteriorating due to discharged gas and to prevent mounting efficiency of a printed board from dropping without increasing the weight of an entire device or complicating the console structure. CONSTITUTION: A damper sheet 5 is pasted to a rear face of a printed board 1 on a main part obtained by a vibration analysis result, that is a part where displacement is maximum or a phase is reversed when the printed board 1 is resonates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping structure for a printed board, and more particularly to a vibration damping mounting method for a printed board used in electronic equipment in the aerospace field exposed to the surrounding environment such as vibration and shock.

[0002]

2. Description of the Related Art Conventionally, in a printed circuit board mounted on an electronic device, in order to protect mounted electronic components from the influence of the surrounding environment such as vibration and shock, the entire printed circuit board has a certain thickness of foam. There is a method of covering with a conductive material.

There is also a method of preventing damage to the mounted electronic components by increasing the number of mounting positions of the printed board or mounting a vibration proof rubber at the mounting locations so that the printed board itself does not vibrate excessively.

A method for protecting mounted electronic parts from the influence of the surrounding environment such as the above-mentioned vibration and shock is disclosed in Japanese Patent Laid-Open Publication No.
3-102300 and the method disclosed in Japanese Utility Model Publication No. 1-
Method disclosed in Japanese Laid-Open Patent Publication No. 133382 and Actual Kaihei 1-
There is a method disclosed in Japanese Patent No. 163385.

[0005]

In the conventional vibration damping mounting method for a printed board described above, in the case of a method of covering the entire printed board with a foam material, rework at the time of repair becomes extremely difficult, and the foam material is used. Since a large amount of gas is released into the vacuum (outgas), the released gas adheres to the lens of the optical system and deteriorates the optical performance.

Further, in the case of the method of increasing the number of mounting points of the printed board, the number of mounting points of the printed board increases the number of fixing portions on the housing side. When the central part is fixed, the structure of the housing becomes complicated, and there are many restrictions on the circuit design of the printed board in order to avoid interference with the circuit pattern of the housing and the printed circuit board, and mounted electronic components. Mounting efficiency decreases.

Further, in the case of the method of attaching the vibration proof rubber to the mounting location, the vibration can be absorbed only in a certain frequency band having a low frequency range, or the natural frequency is extremely lowered, and the vibration amplitude is reversed. It may increase. In the case of using this anti-vibration rubber, since the anti-vibration rubber also releases a large amount of gas into the vacuum, as with the foamable material above, the released gas adheres to the lens of the optical system and deteriorates the optical performance. I will let you.

Therefore, an object of the present invention is to solve the above-mentioned problems and prevent rework at the time of repair from becoming extremely difficult and preventing the optical performance of the optical system from being deteriorated by the released gas. Therefore, it is an object of the present invention to provide a vibration damping structure for a printed board that can prevent a reduction in mounting efficiency of the printed board without increasing the weight of the entire apparatus and complicating the housing structure.

[0009]

A vibration control structure for a printed board according to the present invention is a vibration control structure for a printed board of an electronic device mounted on a spacecraft, wherein a transient response generated when the printed board resonates. A vibration-damping sheet made of a vibration-damping material having a high vibration energy absorbing ability for damping the acceleration and suppressing the self-excited vibration of the printed board is provided.

In addition to the above structure, another vibration damping structure for a printed board according to the present invention includes a thin plate which covers the vibration damping sheet and has a high tensile elastic modulus.

[0011]

According to the vibration damping method of the present invention, the main part obtained from the vibration analysis result of the vibration damping sheet formed of the vibration damping material having a high vibration energy absorbing ability on the printed board, that is, the displacement becomes maximum when the printed board resonates. The effect of preventing damage to the electronic components mounted on the printed board can be obtained by attaching the adhesive to a portion or a boundary surface where the phase is inverted to minimize self-excited vibration of the printed board.

Further, regarding the damping sheet, the material and shape,
And by changing the thickness, the frequency band, temperature conditions,
It is possible to select and supply the most suitable material to meet the requirements for degassing (outgassing) characteristics, low specific gravity, and flame retardancy.

[0013]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, the flat package 2, the chip components 3, and the DIP (Dua
Mounted electronic components such as an IInline Package component 4 are mounted, and the printed board 1 is attached to a mounting portion of the housing 6 with screws 7.

On the back surface of the printed board 1, a vibration damping sheet 5 is attached to the main portion obtained from the vibration analysis result, that is, the portion where the displacement is maximum when the printed board 1 resonates and the boundary surface where the phase is inverted. Has been done. The material for the vibration damping sheet 5 is an optimum material (eg, dibrominated epoxy resin, etc.) to meet the requirements of any frequency band, temperature conditions, degassing (outgas) characteristics, low specific gravity, flame retardancy, etc. Can be selected.

FIG. 2 is a vibration mode diagram of the printed board 1 used in one embodiment of the present invention. FIG. 2 is a displacement diagram of the first-order mode. A in FIG. 2 indicates a maximum displacement portion (= measurement point) at the time of resonance of the printed-circuit board 1 when the printed-circuit board 1 is mounted at ten places (first-order mode, 3rd mode) is shown. In one embodiment of the present invention, the damping sheet 5 is attached to the maximum displacement portion of the printed board 1 at the time of resonance.

FIG. 3 is a diagram showing vibration characteristics of the printed board 1 according to an embodiment of the present invention. FIG. 3A shows vibration characteristics when the vibration damping sheet 5 is not attached, and FIG.
Shows vibration characteristics when the damping sheet 5 is attached. 3 is a printed board 1 [100 mm × 150 m
m × 1.6 mm (thickness)] to 26 mm × 26 mm × 1.
Using a vibration damping sheet 5 of a 5 mm (thickness) dibrominated epoxy resin, vibration 10 G, 100 Hz to 2000 Hz, 200
It is a vibration characteristic view when sweeping at t / min.

As shown in these figures, when the vibration damping sheet 5 is not attached, the transient response acceleration (G) at the time of resonance of the printed board 1 becomes 215 G in the primary mode and 510 G in the tertiary mode. On the other hand, when the vibration damping sheet 5 is attached, the transient response acceleration (G) when the printed board 1 resonates
Becomes 150G in the primary mode and 150G in the tertiary mode.

As described above, when the damping sheet 5 is attached to the printed board 1, the transient response acceleration (G) at resonance of the printed board is 30 as compared with the case where the damping sheet 5 is not attached.
% To 70% can be reduced.

FIG. 4 is a sectional view of another embodiment of the present invention. In the figure, another embodiment of the present invention shows that a constraining plate 8 which is a thin plate having a high tensile elastic modulus is provided on the vibration damping sheet 5 [eg,
26 mm × 26 mm × 1.0 mm (thickness)], the configuration is the same as that of the embodiment of the present invention shown in FIG. 1, and the same components are designated by the same reference numerals.

The constraining plate 8 is covered on the vibration damping sheet 5 attached to the portion where the displacement of the printed board 1 is maximum when the printed board 1 resonates or the boundary surface where the phase is inverted, and the flexure when the printed board 1 resonates ( Strain energy) is more easily absorbed than when only the vibration damping sheet 5 is used. As a result, the other embodiment of the present invention can further improve the vibration damping effect than the one embodiment of the present invention.

As described above, the transient response acceleration generated at the resonance of the printed board 1 of the electronic equipment (not shown) mounted on the spacecraft (not shown) is attenuated and the self-excited vibration of the printed board 1 is suppressed. By attaching the vibration damping sheet 5 made of a vibration damping material having a high vibration energy absorbing ability to at least one of the portion of the printed board 1 where the displacement is maximum at the time of resonance and the boundary surface where the phase is inverted, , Printed board 1
It is possible to attenuate the transient response acceleration generated at the time of resonance and suppress the self-excited vibration of the printed board 1.

As a result, by suppressing the self-excited vibration of the printed board 1 to the minimum, it is possible to prevent the electronic parts mounted on the printed board 1 from being damaged, and the entire printed board 1 can be protected as in the prior art. Since it is not covered with foamable material,
Rework for refurbishment becomes extremely easy.

Further, by using a material such as an epoxy dibromide resin, which releases a small amount of gas (outgas) into a vacuum, as the material of the vibration damping sheet 5, the released gas adheres to the lens of the optical system. Is reduced, it is possible to prevent the optical performance of the optical system from deteriorating.

Further, since it is not necessary to increase the number of mounting positions of the printed board 1 or to attach the vibration proof rubber to the mounting positions, the weight of the entire apparatus can be increased without increasing the fixing portion on the housing 6 side. Since it is not necessary to fix the central part of the printed board 1, the structure of the housing 6 can be simplified and the circuit design of the printed board 1 is less restricted. You can prevent the decline.

In other words, it is possible to prevent rework at the time of refurbishment from becoming extremely difficult, and to prevent the optical performance of the optical system from being deteriorated by the released gas, increasing the weight of the entire apparatus and the housing structure. It is possible to prevent the mounting efficiency of the printed board 1 from decreasing without complicating.

Since the vibration damping sheet 5 can be designed in terms of material design, cross-sectional shape, thickness, specific gravity, etc. that absorb specified vibration energy in an arbitrary frequency band, the most effective vibration damping method can be adopted. There is an advantage that you can.

[0028]

As described above, according to the present invention, the vibration that attenuates the transient response acceleration generated when the printed board of the electronic equipment mounted on the spacecraft resonates and suppresses the self-excited vibration of the printed board. By attaching a damping sheet made of a damping material with high energy absorption capacity to at least one of the part where the displacement is maximum when the printed board resonates and the boundary surface where the phase is inverted, rework during repair can be performed. It is possible to prevent it from becoming extremely difficult or degrading the optical performance of the optical system due to the released gas, without increasing the weight of the entire device and complicating the housing structure,
There is an effect that it is possible to prevent a reduction in the mounting efficiency of the printed board.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a vibration mode diagram of a printed board used in an embodiment of the present invention.

3A is a diagram showing vibration characteristics when the damping sheet of FIG. 1 is not attached, and FIG. 3B is a diagram showing vibration characteristics when the damping sheet of FIG. 1 is attached. is there.

FIG. 4 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Printed board 5 Damping sheet 6 Housing 7 Screw 8 Restraint plate

Claims (4)

[Claims] 1. A vibration control structure for a printed board of an electronic device mounted on a spacecraft, which attenuates transient response acceleration generated when the printed board resonates and suppresses self-excited vibration of the printed board. A vibration-damping structure for a printed board, comprising a vibration-damping sheet made of a vibration-damping material having high vibration energy absorption ability. 2. The vibration damping sheet is configured to be attached to at least one of a portion in which the displacement of the printed board is maximum when the printed board resonates and a boundary surface where the phase is inverted. Damping structure of the printed board described. 3. The vibration damping material is a material having a low specific gravity having degassing characteristics and flame retardancy.
Alternatively, the printed board vibration damping structure according to claim 2. 4. The vibration damping structure for a printed board according to claim 1, further comprising a thin plate which covers the vibration damping sheet and has a high tensile elastic modulus.