JPH03235412A - Developing method for printed board - Google Patents

Abstract

PURPOSE:To remove developing unevenness, and simultaneously, to shorten developing time by rotating a board in a developer, and moving every part of the board close by an ultrasonic wave oscillator to ultrasonic-vibrate the developer. CONSTITUTION:While the developer 6 is ultrasonic-vibrated by the ultrasonic wave oscillator 7 as swinging the board 1 immersed in the developer (pure water) 6 up and down and right and left, the board 1 held by a jig 5 is rotated, and the part of the board 1 positioned far away from the ultrasonic wave oscillator 7 is moved by turns to the vicinity of the ultrasonic wave oscillator 7. Thus, every part of the printed board 1 brought into contact uniformly with the developer 6 ultrasonic-vibrated by strong energy at the vicinity of the ultrasonic wave oscillator 7.

Description

[Detailed Description of the Invention] [Summary] Regarding a photoresist development method, the purpose is to prevent uneven development and shorten the development time. After partially exposing the printed circuit board, the printed circuit board is immersed in a developer, and the photoresist is developed while the developer is vibrated ultrasonically using an ultrasonic oscillator. The structure was such that the substrate was rotated in the developer.

[Industrial Application Field] The present invention relates to a method for developing a photoresist such as a photocurable (photosensitive) polymide that is formed as an insulating layer on the surface of a printed circuit board, such as a ceramic substrate.

[Conventional technology]

In recent years, as printed wiring boards used in computers, etc., a surface multilayer film consisting of a metal layer that forms a conductive pattern and an insulating layer is formed on the surface of a ceramic substrate, and mounted parts and components are mounted on the surface of the surface multilayer film. A system has been developed in which a ceramic substrate is connected to a circuit through a via conductor that penetrates a metal layer and a core insulating layer in a surface multilayer film. This surface multilayer film is formed, for example, according to the procedure shown in FIG.

That is, the coating process (b) is applied to the surface of a ceramic substrate (hereinafter simply referred to as a substrate) 1 whose surface has been polished in the polishing process (a).
), for example, photosensitive polyimide 2 is applied as a liquid or gel photoresist, and in the exposure step (C), the portions corresponding to, for example, the peer holes 2a are covered with the light-shielding portions 3a of the pattern mask 3, thereby forming the pattern of the insulating layer 2. Only the portion 2b is exposed to light and photocured, and in the development step (d), the uncured photosensitive polyimide 2 in the portion of the pier hole 2a is eluted into the developer 6 and removed, resulting in the image shown in FIG. As shown, a pier hole 2a penetrating the photosensitive polyimide (insulating layer) 2 is formed.

In the development step (d), the substrate 1 to which the photosensitive polyimide 2 is attached is held by a jig 15 suspended by a hanger frame 9 and immersed in a developer (pure water) 6. In order to shorten the development time, the substrate 1 is swung both vertically and horizontally along the surface direction within the developer 6 using the swing drive device 10 via the hanger frame 9 and the jig 15. The developer 6 is vibrated ultrasonically by the ultrasonic oscillator 7.

After this, in the metal thin film forming step (, f), sputtering,
Metal thin film 8 consisting of via conductor 8a and surface conductor 8b is formed by a known thin film forming method such as vapor deposition. Then, in a pattern forming step (g), the surface conductor 8b is formed into a predetermined pattern by etching or the like.

The steps from the coating step (b) to the pattern forming step (g) of the surface conductor 8b are repeated multiple times as necessary. Finally, a footprint for connecting mounted components is formed as a surface conductor 8b on the surface of the surface multilayer film. Although there is a positional error in the position of the footprint and the corresponding position of the conductor on the surface of the substrate 1 due to shrinkage of the substrate 1, the position of the peer hole 3 of each insulating layer 2 can be adjusted little by little, for example, by 5 to 10 μm. By shifting, the footprint and the conductor of the substrate 1 are connected through the via conductor 8a and the surface conductor 8b filled in the peer hole 3 of each insulating layer 2.

[Problem to be solved by the invention]

However, in the developing step (d), the energy of the ultrasonic waves propagating from the ultrasonic oscillator 4 to the developer 5 rapidly attenuates as the distance from the ultrasonic oscillator 4 increases.
The state of elution of seeds such as a varies depending on the distance from the ultrasonic oscillator 7, and it takes a long time to elute uncured parts such as the pier hole 2a at a position far from the ultrasonic oscillator 7 than a predetermined species. There is a problem that it takes.

The present invention has been developed in consideration of the above circumstances, and an object of the present invention is to provide a method for developing a photosensitive synthetic resin that can prevent the occurrence of uneven development and shorten the development time.

[Means to solve the problem]

The present invention provides a printed circuit board 1 as shown in FIG. 1, for example.
After applying a photoresist to the surface of 0 and partially exposing the photoresist, the printed circuit board 1 is immersed in a developer 6, and the photoresist is developed while the developer 6 is vibrated ultrasonically by an ultrasonic oscillator 7. In the developing method, in order to achieve the above object, a measure is taken in which the direction of the printed circuit board 1 is rotated in the developer 6.

[For production]

In the present invention, by rotating the direction of the printed circuit board 1 in the developer, it is possible to move the portion of the printed circuit board l located far away from the ultrasonic oscillator 7 closer to the ultrasonic oscillator 7. , each part of the printed circuit board 1 can be sequentially and evenly brought into contact with the developer 6 vibrating ultrasonically with strong energy near the ultrasonic oscillator 7.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram of a developing device for carrying out a method for developing a polyimide insulating layer according to an embodiment of the present invention. This method for developing a polyimide insulating layer is shown in FIG. ) and the development step (d) performed after the exposure step (c).

That is, the substrate 1 whose surface has been polished in the polishing step (a)
In the coating step (b), a gel-like photosensitive polyimide (hereinafter simply referred to as polyimide) 2 is coated to a predetermined thickness. After that, in an exposure step (C), a pattern mask 3 leaving a light shielding part 3a corresponding to, for example, the pier hole 2a is covered and exposed. In this exposure process,
The pattern portion 2b of the polyimide 2 is cured by being exposed to the light that has passed through the transparent portion 3b of the pattern mask 3, and the portion of the pier hole 2b covered by the light shielding portion 3a of the pattern mask 3 remains uncured. .

Now, in this developing step (d), by using a jig 5 to be described later, the substrate 1 immersed in the developer (pure water) 6 is developed with an ultrasonic oscillator 7 while being swung vertically and horizontally. While the liquid 6 is being ultrasonically vibrated, the substrate 1 held in the jig 5 is rotated, and parts of the substrate 1 located far away from the ultrasonic oscillator 7 are sequentially moved closer to the ultrasonic oscillator 7. ing.

Here, the substrate 1 is moved 90 degrees along the surface every 15 seconds.
Although an intermittent manual rotation operation was performed in which the substrate 1 was rotated by degrees in a fixed direction, the substrate 1 may be rotated continuously using a motor or the like, for example.

Further, when the substrate 1 is rotated continuously, the rotation speed may be kept constant, or the rotation speed may be changed such that it becomes slower at the corners of the substrate 1.

Further, the rotation speed of the substrate 1 is not particularly limited, but it is preferably set so that it rotates at least once within the development processing time. The development processing time is roughly determined by the concentration of the developer 6, the size of the substrate 1, the area of uncured parts such as the peer holes 2a of the polyimide 2, etc., but in this example, the development processing time is 1 to 1.5 minutes. Therefore, the substrate 1 was rotated once in the processing time by rotating in a fixed direction by 90° every 15 seconds to 22.5 seconds as described above.

The jig 5 may be configured so that the substrate l held thereon can be rotated one rotation or more, and for example, as shown in FIGS. 1, 2, and 3, The holder frame 52 may be configured by a support frame 51 that holds the substrate 1 and is rotatably supported by the support frame 51.

As shown in FIGS. 2 and 3, the support frame 51 includes a main body 51a, a pair of hooks 51b and 51b provided on the upper part of the main body 51a at an appropriate distance from each other, and a lower part of the entire surface of the main body 51a. and a ring 51c supported at a predetermined distance from the main body 51a. The holder frame 52 includes a pair of front and rear square frames 52a and 52b, and a roller 5 rotatably supported at the center of each side of the rear square frame 52b.
Equipped with 2C. The outer peripheral surface of each roller 52c is a ring 51
The holder frame 52 is attached to the hanger frame 51 by fitting the outer circumferential surface of the roller 52c to the outer circumferential surface of the ring 51c in a movable manner. It is designed to be rotatably supported.

Furthermore, each of the square frames 52a and 52b of the holder frame 52
Tightening bolts 53, which are rotatably inserted into the front square frame 52a and screwed into the rear square frame 52b so that they can be screwed back and forth, are provided at two locations at appropriate intervals on each side. and each square frame 52a, 5 of the holder frame 52.
Board holders 54a and 5 protrude inside each square frame 52a and 52b at two locations on each side of 2b at appropriate intervals.
4b are arranged in series. And both square frames 52a and 52b
By inserting the peripheral edge of the board 1 between the mutually corresponding board holding parts 54a and 54b and tightening the respective tightening bolts 53, the mutually corresponding board holding parts 53a and 53
The peripheral edge of the substrate 1 is held between the two portions b.

In the development step (d), portions such as the uncured pier holes 2a that were not exposed in the exposure step are eluted into the developer, and the patterned portions of the polyimide 2 are formed on the surface as shown in FIG. 4(e). A substrate 1 with 2b remaining is obtained.

According to the developing method according to this embodiment, the substrate 1 is coated with the developing solution 6.
By rotating each part of the substrate 1 in turn, it is moved closer to the ultrasonic oscillator 7.

As a result, each part of the substrate 1 is brought into uniform contact with the developer 6 which vibrates ultrasonically with strong energy in the vicinity of the ultrasonic oscillator 7. As a result, uncured pier hole 2
The polyimide 2 of a is efficiently eluted into the developer 6 over the entire substrate 1, and the state of the elution is averaged.

An experiment was conducted in which a large number of pier holes 2a each having a diameter of 80 μm were formed on the surface of a 260111 square substrate 1 using the developing method according to this example and the conventional developing method. As a result, in the conventional example, the processing time was 2 to 3 minutes, and the average finished diameter χ
= 74.4 μm 1 Maximum deviation value o = 6.67 μm. On the other hand, in the example, the processing time was halved to about 1 to 1.5 minutes, and the average finished diameter χ=80.3
μm, the maximum deviation value o=3.66 μm, and the variation in pier hole diameter was reduced to less than half.

Although the above embodiment has been described with reference to the case where the peer hole 2a is formed in the polyimide 2 as an insulating layer formed on the surface of the substrate 1, the present invention is not limited to this case. It is also widely applied when developing photoresist patterns.

〔Effect of the invention〕

As described above, according to the present invention, by rotating the substrate in the developer solution, each part of the substrate is sequentially moved to the vicinity of the ultrasonic oscillator that ultrasonically vibrates the developer solution. As a result, the photosensitive synthetic resin adhered to the surface of each part of the substrate is sequentially contacted with the developer that vibrates ultrasonically with strong energy and is developed with high efficiency, which eliminates uneven development and reduces the processing time. Can be shortened.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a developing device for carrying out a method for developing a polyimide insulating layer according to an embodiment of the present invention, and FIG.
FIG. 3 is a front view of the jig, FIG. 3 is a side view of the jig, and FIG. 4 is a flowchart of the step of forming a surface multilayer film on a ceramic substrate. In the figure, 1... Ceramic substrate, 2... Photo-curable polyimide, 6... Developer, 7... Ultrasonic oscillator. 1 o ratio duty 5 oar 1st column of 14th row 1st w Continuous layer, l-plane drawing 2nd figure

Claims (1)

[Scope of Claims] [1] After applying a photoresist to the surface of a printed circuit board (1) and partially exposing the photoresist, the printed circuit board (1) is immersed in a developer (6), Developer (6)
In this development method, the printed circuit board (1) to which the partially exposed photoresist (2) is attached is rotated in the developer (6). A developing method for a printed circuit board, characterized by: