KR100642741B1 - Method for making double sides wiring substrate - Google Patents

Abstract

Forming a first seed layer on one side of the prepared polyimide substrate; Forming a first plating layer over the first seed layer; Forming a via hole by processing only the polyimide substrate so that the diameter at the inlet and the bottom is the same from the other side opposite to the one side of the polyimide substrate; Forming a second seed layer on the other side of the polyimide substrate; Forming a second plating layer such that the other side of the polyimide substrate including the second seed layer is planarized; And coating a photoresist on the first and second plating layers, performing patterning through exposure and development in response to a predetermined pattern, and peeling the photoresist.

Wiring Board, Laser, Both Sides, Via Hole, Fine Pitch, Seed Layer, Drill

Description

Method for making double sides wiring substrate

1 is a process chart showing a manufacturing method of a double-sided wiring board according to the present invention.

The present invention relates to a method for manufacturing a double-sided wiring board, and more particularly, by forming a via hole after the formation of a lead pattern, the via-hole pattern alignment of both sides is precisely achieved, and the double-sided wiring board capable of realizing fine pitch by laser etching. It relates to a manufacturing method of.

In double-sided wiring boards such as double-sided tape carriers, which are used as electronic components, wiring patterns such as inner leads are generally formed on the substrate surface, and various hole patterns such as via holes and ground patterns are formed. Is formed on the back side.

The via hole is a through hole penetrating through the insulator substrate and leading to the conductive lead, and serves to electrically conduct the lead and the back surface formed on the surface by plating a metal on the wall thereof.

Wet etching, laser processing, a mechanical drill, etc. are applied as a processing method of a via hole.

Referring to the method of processing via holes, first, a metal layer of several microns is formed on both sides of an insulator substrate made of polyimide by electroless copper plating.

After the photoresist is applied to the back surface, a desired via hole pattern is patterned using photolithography technology, and the metal layer is exposed by exposing and developing according to the formed pattern.

Subsequently, when the exposed metal layer is etched and the residual photoresist is subsequently peeled off, since the via hole pattern is formed in the metal layer, the insulator substrate at the desired via hole formation position is exposed.

Subsequently, the metal layer on which the via-hole pattern is formed is immersed in a strong alkali solution as an etching mask, and the exposed insulator substrate is wet-etched to completely remove the insulator substrate to reach the surface lead, thereby forming through holes in the portion to obtain a desired via hole. Can be.

On the other hand, in recent years, as the demand for higher density increases, narrower pitches and multi-pinning of lead widths are progressing. For example, when applied to a product having a narrow pitch with a lead space of 40 μm for a lead width of 40 μm or less, a via hole is also used. Thus, it must be formed on an extremely narrow lead.

The via hole is not allowed to protrude from the land so that the diameter of the via hole hole needs to be made smaller than the width of the land.

However, as described above, when forming the through-hole by dissolving the insulator by the wet etching method, since the lateral etching called side etching also proceeds simultaneously, the wall surface of the through-hole is not vertically formed, thereby forming a taper. The opening diameter of the insulator substrate surface becomes larger than the opening diameter of the back surface.

In addition, the via hole must be densified with higher density of the lead pattern, but the distance between adjacent via holes also becomes smaller. Therefore, the opening diameter of the surface of the insulator substrate is increased by side etching. do.

Accordingly, it is an object of the present invention to provide a method for manufacturing a double-sided wiring board which minimizes problems related to the shape of the via hole such as the nonuniformity of the diameter inside the via hole generated when forming the via hole.

Another object of the present invention is to provide a method for manufacturing a double-sided wiring board capable of realizing fine pitch by laser etching.

Further objects, features and advantages of the present invention will be more clearly understood through the embodiments described below.

According to the present invention, forming a first seed layer on one side of the prepared polyimide substrate; Forming a first plating layer over the first seed layer; Forming a via hole by processing only the polyimide substrate so that the diameter at the inlet and the bottom is the same from the other side opposite to the one side of the polyimide substrate; Forming a second seed layer on the other side of the polyimide substrate; Forming a second plating layer such that the other side of the polyimide substrate including the second seed layer is planarized; And coating a photoresist on the first and second plating layers, performing patterning through exposure and development in response to a predetermined pattern, and peeling the photoresist.

Preferably, forming a mounting conductive layer to cover exposed portions of the first and second seed layers and the first and second metal layers, and applying the exposed portions of the polyimide with a non-conductive solder resist It may further include.

In addition, the predetermined pattern corresponds to the ground pattern and the via land in the first plating layer, and corresponds to the lead pattern and the via hole pattern in the second plating layer.

Preferably, the via hole is formed by a laser beam or a mechanical drill.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a process chart showing a manufacturing method according to an embodiment of the present invention.

Referring to FIG. 1, a polyimide substrate 10 having a thickness of 20 to 200 μm is prepared (FIG. 1A).

Subsequently, as illustrated in FIG. 1B, the first seed layer 20 having a thickness of preferably 1 μm or less is formed on the back surface of the substrate 10. The first seed layer 20 forms one of Ni, Pd, Cr or Cu or a mixture thereof by sputtering or electroless plating.

Alternatively, the first seed layer 20 may be formed, and the first plating layer 30 for wiring using copper or the like may be continuously formed thereon.

Subsequently, as shown in FIG. 1D, the via hole 12 is formed by processing only the polyimide substrate 10 using a laser beam or a mechanical drill on a surface opposite to the back surface on which the seed layer 20 is formed. . The formed via hole 12 is formed corresponding to a preset via hole pattern.

As such, since only the polyimide substrate is processed, there is an advantage in that the selection of the drilling source, such as a laser beam or a mechanical drill, can be expanded. In particular, by using a laser beam, since a via hole having a fine diameter can be formed, it becomes denser and can cope with a lead pattern having a fine line width.

In particular, in the prior art, since the lateral etching, also called side etching, proceeds at the same time, the wall surface of the through hole is not formed vertically, but a taper is formed. According to the present invention, the side surface of the via hole 12 and the seed layer 20 are formed. ) Is almost vertical, not exceeding 100 °.

After the via hole 12 is formed, the second seed layer 20a is formed on the entire surface of the polyimide substrate 10 by sputtering or electroless plating, as shown in FIG. 1 (e), and as shown in FIG. 1 (f). The second plating layer 30a is formed thereon so as to planarize the entire surface thereof.

Referring to FIG. 1G, the photoresist 40 is coated on the entire surface of the first and second plating layers 30 and 30a, and the back surface on which the first plating layer 30 is formed corresponds to a ground pattern and a via land. Patterning is performed on the surface on which the second plating layer 30a is formed through exposure and development so as to correspond to the lead pattern and the via hole pattern. The photoresist may use a liquid or dry film.

Subsequently, as shown in FIG. 1H, after the patterning of the photoresist 40 is completed, the photoresist 40 is peeled off.

Referring to FIG. 1 (i), the mounting conductive layer 50 is formed to cover the exposed first and second seed layers 20 and 20a and the first and second plating layers 30 and 30a. Gold or tin can be used.

In addition, a non-conductive solder resist 60 is applied on the exposed polyimide substrate 10 to protect the substrate.

In the above embodiment, as shown in the figure, the upper side is referred to as the surface, the lower side is referred to as the back side, which is for convenience of explanation and the same result can be obtained even if the reverse process.

Although the above has been described with reference to the preferred embodiments of the present invention, various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limited to the above embodiments, but should be determined by the claims described below.

 As described above, the present invention has various advantages.

First, since only polyimide substrates are processed, there is an advantage in that the choice of drilling source, such as a laser beam or a mechanical drill, can be expanded.

In addition, by using the laser beam, there is an advantage that the difference in diameter between the inlet and the bottom of the via hole can be minimized. In addition, since a via hole having a fine diameter can be formed, it is possible to correspond to a lead pattern having a high density and a fine line width.

Claims (4)

Forming a first seed layer on one side of the prepared polyimide substrate; Forming a first plating layer on the first seed layer; Forming a via hole by processing only the polyimide substrate so that the diameter at the inlet and the bottom surface is the same from the other surface opposite to one side of the polyimide substrate; Forming a second seed layer on the other side of the polyimide substrate; Forming a second plating layer such that another surface of the polyimide substrate including the second seed layer is planarized; And And applying a photoresist on the first and second plating layers, performing patterning through exposure and development corresponding to a predetermined pattern, and peeling the photoresist. 2. The method of claim 1, further comprising: forming a mounting conductive layer to cover exposed portions of the first and second seed layers and the first and second metal layers, and exposing the exposed portions of the polyimide to non-conductive solder. The method of manufacturing a double-sided wiring board further comprising the step of applying with a resist. The double-sided wiring board of claim 1 or 2, wherein the predetermined pattern corresponds to a ground pattern and a via land in the first plating layer and a lead pattern and a via hole pattern in the second plating layer. Manufacturing method. The method of claim 1 or 2, wherein the via hole is formed by a laser beam or a mechanical drill.

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