JPH047064A - Spin coating method for ceramic substrates - 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] [Summary] Regarding a ceramic substrate spin coating method for printed circuit boards that is widely used in the construction of various electronic devices, the present invention relates to a ceramic substrate spin coating method that can form a uniform thin film of a coating agent on the surface of the substrate. For the purpose of providing a spin coating method, a certain amount of a coating agent is dropped onto a substrate fixed on a rotating table of a spin coating device, and when the coating agent naturally spreads to a certain size on the substrate, The rotary table is rotated at a low speed of about 50 rpm, and kept at the low speed until the outer periphery of the coating agent reaches each end surface of the substrate, and then the rotation speed is rotated at a constant acceleration of about 2
After increasing the speed to 000 rpm and holding it for a certain period of time, it is stopped.

[Industrial Field of Application] The present invention relates to a ceramic substrate spin coating method for printed boards, which is widely used in the construction of various electronic devices.

Recently, printed circuit boards used in large computers, etc. are required to have larger circuit scales and higher speeds, and as a result, ceramic boards have become larger and the conductor patterns formed on the boards have to be smaller and more dense. It has become. However, since the conductor pattern described above is formed by spin-coating photoresist on the surface of the substrate and then developing the predetermined pattern to form a conductor pattern with a fine width, unevenness in the thickness of the formed photoresist film may cause uneven development. As a result, the line width accuracy of the formed conductor pattern deteriorates, so there is a need for a new ceramic substrate spin coating method that can form a uniform photoresist thin film on the surface of the substrate.

[Prior Art] In the conventionally widely used spin coating method for ceramic substrates, as shown in FIG. Then, the substrate 1 is suctioned and fixed by a vacuum chuck 3-1a provided on a rotary table 3-1, and a photoresist or the like is applied through a nozzle 3-2 provided at the upper part facing the center of the rotary table 3-1. Coating agent 2 with high viscosity is applied to substrate 1
A certain amount of water is dripping onto the top surface.

Then, as shown in FIG. 2, the rotary table 3-1 is accelerated in rotation in the direction of the arrow, for example, from point E at the same time as the coating agent 2 is dropped, and the rotation is approximately 2000 rpm. By holding the rotation speed at this speed for a certain period of time from point F, the coating agent 2 flows toward the outer periphery due to centrifugal force, and the excess coating agent 2 is scattered from the outer periphery of the substrate 1. By sequentially decelerating and stopping the rotation at the zero point, a photoresist thin film of approximately 10 μm is formed on the surface of the substrate.

[Problems to be Solved by the Invention] The problem with the conventional spin-coating method for ceramic substrates described above is that the coating agent 2 spin-coated on the top surface of the substrate 1, as shown in FIG. The film thickness is uniform inside the circle touching each end surface of the substrate 1, but the coating agent 2 outside the circle has an arc-shaped pattern toward each corner of the substrate 1. As shown in the cross-sectional view of FIG. 4(b), the film thickness of the coating agent 2 in this part is wavy with an average film thickness of about 10 μm, and uneven development occurs during pattern development. A problem has arisen in that the line width accuracy of the conductor pattern is degraded.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to provide a new spin coating method for a ceramic substrate, which can form a uniform thin film of a coating agent on the surface of the substrate.

[Means for Solving the Problems] The present invention, as shown in FIG. 3, drips a certain amount of coating agent 2 onto a substrate l fixed on a rotary table 3-1 of a spin coater 3, and then coats the substrate in a natural state. The coating agent 2
is spread to a constant diameter on the substrate, the rotary table 3-1 is rotated at a low speed of about 500 rpm as shown in FIG.
is rotated and held at low speed until the outer periphery of the coating agent 2 reaches each end surface of the substrate 1, then the rotation speed is increased to about 2000 rpm with a constant acceleration, held for a certain period of time, and then stopped.

[Two functions] In the present invention, when the coating agent spreads to a certain diameter on the substrate, a rotary table as shown in Fig. 1 is rotated at a low speed, and then the rotation speed is increased at a constant acceleration. Experiments have shown that by holding the coating for a certain period of time and then stopping it for two seconds, the thickness of the coating agent formed on the surface of the substrate can be made uniform.

Embodiments] The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 shows a time chart of the spin coating method for a ceramic substrate according to this embodiment.

In the spin coating method of this embodiment, as shown in FIG. The coating agent 2 is suctioned and fixed by the vacuum chuck 3-1a, and a certain amount of the coating agent 2 is dropped onto the upper surface of the substrate l from a nozzle 3-2 provided at the upper part of the rotary table 3-1.

Then, the dropped coating agent 2 is applied to the substrate l in its natural state.
When it spreads out into a circle with a diameter of about 1/4 of one side,
That is, from point A shown in FIG. 1, the rotary table 3-1 is rotated approximately 500 rpm in the direction of the previous arrow by a control circuit (not shown).
The substrate 1 is rotated at a low speed until the coating agent 2 spreads due to the centrifugal force and its outer periphery reaches each end surface of the substrate 1 at a low speed. After that, it is accelerated so that the rotation speed reaches 2000 rpm, which is the same as before, for a certain period of time 3, for example, 10 seconds, and from the 0 point where it reaches this high speed of 2000 rpm, it is rotated at that high speed for a certain period of time, and from point D, it is decelerated to a certain degree. to stop it.

As a result, a uniform thin film of the coating agent 2 can be formed on the surface of the substrate 1.

[Effects of the Invention] As is clear from the above explanation, the present invention has advantages such as being able to form a uniform thin film of coating agent on the surface of the substrate by an extremely simple method, and has the effect of significantly improving the reliability. It is possible to provide a spin coating method for ceramic substrates that can be expected to provide the following benefits.

[Brief explanation of the drawing]

FIG. 1 is a time chart showing a spin coating method for a ceramic substrate according to an embodiment of the present invention, FIG. 2 is a time chart showing a conventional spin coating method, and FIG. 3 is a schematic cross-sectional view showing a spin coating apparatus. FIG. 4 is a diagram showing the problem. In the figure, ① indicates a substrate, and 2 indicates a coating agent.

Claims (1)

[Claims] A certain amount of the coating agent (2) is dropped onto the substrate (1) fixed on the rotary table (3-1) of the spin coater (3), and the coating agent (2) is kept constant on the substrate in a natural state. When it has spread to a size of , rotate the rotary table (3-1) at a low speed of about 500 rpm and hold it at low speed until the outer periphery of the coating agent (2) reaches each end surface of the substrate (1). . A method for spin coating a ceramic substrate, which comprises: increasing the rotational speed to approximately 2000 rpm at a constant acceleration, holding the rotation speed for a certain period of time, and then stopping the rotation speed.