JP2015215585A - Photosensitive insulator film for via hole formation, and via hole formation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive insulator film for via hole formation, and a via hole formation method using the same.SOLUTION: According to one embodiment of the present invention, a photosensitive insulator film for via hole formation comprises a base substrate, a first insulator film formed on the base substrate, and a second insulator film formed on the first insulator film. The photosensitivity of the first insulator film is greater than the photosensitivity of the second insulator film.

Description

  The present invention relates to a photosensitive insulating film for forming a via hole and a method for forming a via hole using the same.

  The printed circuit board is obtained by laminating a copper foil for wiring on a substrate made of a material such as a polymer resin, and forming a pattern so as to match the design circuit by techniques such as pattern printing and etching. .

  Recently, with the development of electronic technology, the density of printed circuit boards has been gradually increased. As a result, the size and thickness of the printed circuit board are reduced, and the number of vias provided in the printed circuit board is further increased.

  Conventionally, an epoxy resin composition is cured as an interlayer insulating film of a multilayer printed wiring board to form a cured film, and then via holes are formed in a printed circuit board by a laser drill or drill tip process. It was.

  However, the laser drill and drill tip process has a problem in that it requires a lot of equipment and time since the number of via holes in the printed circuit board has recently exceeded tens of thousands to hundreds of thousands per panel.

  Therefore, a method of forming a via hole by photolithography is used. This is a technique in which an epoxy resin or the like is modified and a photoinitiator is introduced so that a via hole can be formed by exposure and development processes.

  Although this technique has the advantage that a large number of holes can be formed at one time, an open defect of a via hole occurs depending on the exposure amount, or a defect occurs during via fill plating depending on the shape of the via hole formed. There was a problem to do.

JP 2007-042395 A

  One embodiment of the present invention is a photosensitive insulating film for forming a via hole that can prevent a via hole open defect when forming a via hole by exposure and development processes, and can form a via hole having a shape that does not cause a defect during via fill plating. And a via hole forming method using the same.

  One embodiment of the present invention includes a base substrate, a first insulating film formed on the base substrate, and a second insulating film formed on the first insulating film. Provided is a photosensitive insulating film for forming a via hole, wherein the photosensitivity of the insulating film is higher than the photosensitivity of the second insulating film.

The difference in the exposure amount of the first insulating film and the second insulating film may be ^{100mJ / cm 2 ~1000mJ / cm 2} .

The first difference in the exposure amount in the insulating film and the second insulating film may be ^{200mJ / cm 2 ~500mJ / cm 2} .

  The first insulating film may have a thickness of 10 μm to 100 μm.

  The thickness of the second insulating film may be 1 μm to 50 μm.

  The thickness ratio between the first insulating film and the second insulating film may be 1: 1 to 100: 1.

  Another embodiment of the present invention is a base substrate, a first insulating film formed on the base substrate, and formed on the first insulating film and having a lower photosensitivity than the first insulating film. A via hole penetrating the first insulating film and the second insulating film, wherein the via hole has a taper shape with an upper diameter larger than a lower diameter. Insulating film is provided.

  The via hole may have a ratio of a lower diameter to an upper diameter of 0.6 or more.

The difference in the exposure amount of the first insulating film and the second insulating film may be ^{100mJ / cm 2 ~1000mJ / cm 2} .

The first difference in the exposure amount in the insulating film and the second insulating film may be ^{200mJ / cm 2 ~500mJ / cm 2} .

  The first insulating film may have a thickness of 10 μm to 100 μm.

The thickness of the second insulating film may be 1 μm to 50 μm.

  The thickness ratio between the first insulating film and the second insulating film may be 1: 1 to 100: 1.

  Another embodiment of the present invention includes a base substrate, a first insulating film formed on the base substrate, and a second insulating film formed on the first insulating film, Providing a photosensitive insulating film for forming a via hole having a photosensitivity of the first insulating film greater than the photosensitivity of the second insulating film; and forming and exposing a patterned mask on the photosensitive insulating film; and And developing the exposed photosensitive insulating film. A method for forming a via hole is provided.

The first difference in the exposure amount in the insulating film and the second insulating film may be ^{200mJ / cm 2 ~500mJ / cm 2} .

  The first insulating film may have a thickness of 10 μm to 100 μm.

  The thickness of the second insulating film may be 1 μm to 50 μm.

  The thickness ratio between the first insulating film and the second insulating film may be 1: 1 to 100: 1.

  The photosensitive insulating film for forming a via hole according to an embodiment of the present invention can prevent a via hole from being defective when forming a via hole by an exposure and development process, and can form a via hole having a shape that does not cause a defect during via fill plating. it can.

It is sectional drawing of the photosensitive insulating film for via-hole formation by one Embodiment of this invention. It is sectional drawing of the photosensitive insulating film in which the via hole by one Embodiment of this invention was formed. It is sectional drawing which showed the via hole formed in the insulating film whose photosensitivity of a 2nd insulating film is larger than the photosensitivity of a 1st insulating film. It is sectional drawing of the photosensitive insulating film in which the via hole by one Embodiment of this invention which showed the upper diameter and lower diameter of the via hole was formed. 1A and 1B sequentially illustrate a method for forming a via hole according to an embodiment of the present invention. 1A and 1B sequentially illustrate a method for forming a via hole according to an embodiment of the present invention. 1A and 1B sequentially illustrate a method for forming a via hole according to an embodiment of the present invention. It is the photograph which observed the via hole formed in the insulating film whose photosensitivity of a 2nd insulating film is larger than the photosensitivity of a 1st insulating film with the scanning electron microscope (SEM, Scanning Electron Microscope). It is the photograph which observed the cross section of the photosensitive insulating film in which the via hole by one Embodiment of this invention was formed with the scanning electron microscope. It is the photograph which observed the cross section of the photosensitive insulating film in which the via hole by one Embodiment of this invention was formed with the scanning electron microscope.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for a clearer description.

  FIG. 1 is a cross-sectional view of a photosensitive insulating film for forming a via hole according to an embodiment of the present invention.

  Referring to FIG. 1, a photosensitive insulating film 100 for forming a via hole according to an embodiment of the present invention includes a base substrate 10, a first insulating film 21 formed on the base substrate 10, and the first insulation. A second insulating film 22 formed on the film 21, and the first insulating film 21 may have a higher photosensitivity than the second insulating film 22.

  The base substrate 10 is not particularly limited as long as it can perform a support function, and may include, for example, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, or the like, and may have a thickness of 5 μm to 100 μm. .

  The first insulating film 21 and the second insulating film 22 may include a photosensitive material, and adjust the photosensitivity by adjusting the type and content of a photoinitiator and a photosensitizer. be able to.

  By forming the photosensitivity of the first insulating film 21 higher than that of the second insulating film 22, the shape of the via hole can be controlled so that no defect occurs during via fill plating when the via hole is formed by exposure and development processes. it can.

  FIG. 2 is a cross-sectional view of a photosensitive insulating film in which a via hole is formed according to an embodiment of the present invention.

  Referring to FIG. 2, the via hole 30 formed so as to penetrate the first insulating film 21 and the second insulating film 22 may have a tapered shape with an upper diameter larger than a lower diameter.

  Since the photosensitivity of the first insulating film 21 is larger than the second insulating film 22, more photocuring occurs in the first insulating film 21 having a higher photosensitivity than the second insulating film 22 having a lower photosensitivity during exposure. A tapered via hole 30 having an upper diameter larger than the lower diameter can be formed.

  FIG. 3 is a cross-sectional view showing a via hole formed in an insulating film in which the photosensitivity of the second insulating film 24 is greater than the photosensitivity of the first insulating film 23.

  If the photosensitivity of the second insulating film 24 is greater than the photosensitivity of the first insulating film 23, more photocuring occurs in the second insulating film 24. Therefore, as shown in FIG. A via hole 40 is formed. Such a shape of the via hole 40 may cause a problem that voids are generated due to uneven plating during via fill plating.

  Accordingly, in order to prevent defects during via fill plating, the upper diameter is larger than the lower diameter by forming the photosensitivity of the first insulating film 21 larger than that of the second insulating film 22 according to one embodiment of the present invention. A tapered via hole 30 can be formed.

The difference in the exposure amount of the first insulating film 21 and the second insulating film 22 may be ^{100mJ / cm 2 ~1000mJ / cm 2} .

When the difference in exposure dose is less than 100 mJ / cm ² , the first insulating film 21 located at the lower portion is less cured, causing an undercut at the lower portion of the via hole, or having a tapered shape in which the upper diameter is smaller than the lower diameter. If the difference in the exposure dose exceeds 1000 mJ / cm ² , the first insulating film 21 is excessively photocured, resulting in an open failure of the via hole. There is a fear.

A first insulating film 21 is the difference between the exposure amount of the second insulating film ^22, and more preferably ^{200mJ / cm 2 ~500mJ / cm 2} .

The via hole formed when the difference in exposure amount is satisfied has a ratio of the lower diameter r ₂ to the upper diameter r ₁ (r ₂ / r ₁ ) of 0.6 or more. Moreover, the thickness of the 1st and 2nd insulating films 21 and 22 after an exposure and image development process is 70% or more of the thickness before an exposure and image development process.

  The first insulating film 21 may have a thickness of 10 μm to 100 μm, and the second insulating film 22 may have a thickness of 1 μm to 50 μm.

  The thickness ratio between the first insulating film 21 and the second insulating film 22 may be 1: 1 to 100: 1.

  When the thickness ratio of the first insulating film 21 and the second insulating film 22 satisfies the above range, it is possible to prevent a via hole from being poorly opened and to effectively form a tapered via hole in which the upper diameter is larger than the lower diameter. it can.

  FIG. 4 is a cross-sectional view of a photosensitive insulating film having a via hole according to an embodiment of the present invention, showing an upper diameter and a lower diameter of the via hole.

Referring to FIG. 4, the via hole 30 may have a ratio of the lower diameter r ₂ to the upper diameter r ₁ expressed by r ₂ / r ₁ , and r ₂ / r ₁ may be 0.6 or more.

If r ₂ / r ₁ is less than 0.6, the lower diameter r ₂ of the via hole 30 is too small, and a via hole open defect may occur, or pores due to uneven plating during via fill plating may occur.

In order to prevent defects during via fill plating, it is preferable that the upper diameter r ₁ of the via hole 30 has a taper shape larger than the lower diameter r ₂ , so that r ₂ / r ₁ is 0.6 ≦ r ₂ / r _1. <1 can be satisfied.

The first insulating film 21 difference in the exposure amount of the second insulating film 22, more preferably satisfy the ^{200mJ / cm 2 ~500mJ / cm 2} , _thereby, r 2 / _{r 1} is 0.6 or more via holes 30 Is formed.

  The first insulating film 21 and the second insulating film 22 may further include an inorganic filler in order to improve physical properties such as heat resistance and strength.

  Usually, it will not specifically limit if it is an electrically insulating substance used as an inorganic filler, For example, 1 or more selected from the group which consists of a talc, a silica, barium sulfate, and a titanium oxide may be sufficient. The inorganic filler may have a diameter of 10 μm or less. If the diameter of the inorganic filler exceeds 10 μm, the via hole may not be formed well.

  5 to 7 sequentially illustrate a method for forming a via hole according to an embodiment of the present invention.

  Referring to FIG. 5, a via hole forming photosensitive insulating film 100 having a photosensitivity of the first insulating film 21 higher than the photosensitivity of the second insulating film 22 according to an embodiment of the present invention is prepared. After a patterned mask is formed on the insulating film 100, exposure can be performed.

  At the time of exposure, the UV wavelength is not particularly limited, but the exposure can usually be performed with UV having a wavelength of 350 to 450 nm.

  Referring to FIG. 6, the exposed via hole forming photosensitive insulating film 100 may be photocured except for a portion that is covered with the patterned mask and does not reach light.

  At this time, the first insulating film 21 with high photosensitivity can be photocured in a wider area than the second insulating film 22.

  Referring to FIG. 7, the exposed via hole forming photosensitive insulating film 100 can be developed to form a via hole 30.

  In the developing stage, as the developer, a single organic solvent, a mixed organic solvent, or an organic solvent mixed with water may be used, and one or more surfactants may be included.

  Any one selected from the group consisting of spraying the developer onto the insulating film, shaking after immersing the insulating film in the developer, and sonicating the insulating film in the developer. This can be done in one way.

  According to the method for forming a via hole according to an embodiment of the present invention, the open defect of the via hole can be prevented, and the via hole 30 is formed in a tapered shape whose upper diameter is larger than the lower diameter, thereby preventing a defect during via fill plating. Can do.

  FIG. 8 is a photograph of a via hole formed in an insulating film where the photosensitivity of the second insulating film is greater than the photosensitivity of the first insulating film, observed with a scanning electron microscope (SEM). I understand that.

  9 to 10 are photographs obtained by observing a cross section of a photosensitive insulating film in which a via hole is formed according to an embodiment of the present invention with a scanning electron microscope.

FIG. 9 shows a case where the difference in the exposure amount between the first insulating film and the second insulating film exceeds 500 mJ / cm ² , and the lower first insulating film was excessively cured, resulting in open defects in the via holes. Therefore, it is more preferable that the difference of the exposure amount of the first insulating film and the second insulating film is ^{200mJ / cm 2 ~500mJ / cm 2} .

FIG. 10 shows a case where the difference in exposure amount between the first insulating film and the second insulating film is 350 mJ / cm ² , and it can be seen that a tapered via hole having an upper diameter larger than the lower diameter was formed. Thereby, the defect at the time of via fill plating can be prevented.

  The embodiment of the present invention has been described in detail above, but the scope of the present invention is not limited to this, and various modifications and variations can be made without departing from the technical idea of the present invention described in the claims. It will be apparent to those having ordinary knowledge in the art.

100 Photosensitive insulating film 10 for forming via holes Base base materials 21 and 23 First insulating films 22 and 24 Second insulating films 30 and 40 Via holes

Claims (18)

A base substrate;
A first insulating film formed on the base substrate;
A second insulating film formed on the first insulating film,
A photosensitive insulating film for forming via holes, wherein the photosensitivity of the first insulating film is greater than the photosensitivity of the second insulating film. The difference in the exposure amount of the first insulating film and said second insulating film is ^{100mJ / cm 2 ~1000mJ / cm 2} , the photosensitive insulating film for forming the via hole according to claim 1. The difference in the exposure amount of the first insulating film and said second insulating film is ^{200mJ / cm 2 ~500mJ / cm 2} , the photosensitive insulating film for forming the via hole according to claim 1.   The photosensitive insulating film for forming a via hole according to claim 1, wherein a thickness of the first insulating film is 10 μm to 100 μm.   The photosensitive insulating film for forming a via hole according to claim 1, wherein the second insulating film has a thickness of 1 μm to 50 μm.   The photosensitive insulating film for forming a via hole according to claim 1, wherein a thickness ratio of the first insulating film to the second insulating film is 1: 1 to 100: 1. A base substrate;
A first insulating film formed on the base substrate;
A second insulating film formed on the first insulating film and having a lower photosensitivity than the first insulating film;
A photosensitive insulating film for forming a via hole, wherein a via hole penetrating the first insulating film and the second insulating film is formed, and the via hole has a tapered shape with an upper diameter larger than a lower diameter.   The photosensitive insulating film for forming a via hole according to claim 7, wherein the via hole has a ratio of a lower diameter to an upper diameter of 0.6 or more. The difference in the exposure amount of the first insulating film and said second insulating film is ^{100mJ / cm 2 ~1000mJ / cm 2} , the photosensitive insulating film for forming the via hole according to claim 7. The difference in the exposure amount of the first insulating film and said second insulating film is ^{200mJ / cm 2 ~500mJ / cm 2} , the photosensitive insulating film for forming the via hole according to claim 7.   The photosensitive insulating film for forming a via hole according to claim 7, wherein the first insulating film has a thickness of 10 μm to 100 μm.   The photosensitive insulating film for forming a via hole according to claim 7, wherein the second insulating film has a thickness of 1 μm to 50 μm.   The photosensitive insulating film for forming a via hole according to claim 7, wherein a thickness ratio between the first insulating film and the second insulating film is 1: 1 to 100: 1. A base substrate, a first insulating film formed on the base substrate, and a second insulating film formed on the first insulating film, wherein the photosensitivity of the first insulating film is the second insulating film. Preparing a photosensitive insulating film for via hole formation greater than the photosensitivity of
Forming a patterned mask on the photosensitive insulating film and exposing;
Developing the exposed photosensitive insulating film;
A method for forming a via hole including: The difference in the exposure amount of the first insulating film and said second insulating film is ^{200mJ / cm 2 ~500mJ / cm 2} , a method for forming a via hole according to claim 14.   The method for forming a via hole according to claim 14, wherein the first insulating film has a thickness of 10 μm to 100 μm.   The method for forming a via hole according to claim 14, wherein the second insulating film has a thickness of 1 μm to 50 μm.   The method for forming a via hole according to claim 14, wherein a thickness ratio between the first insulating film and the second insulating film is 1: 1 to 100: 1.

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