JP4784009B2 - Processing method of polyimide resin film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for processing a polyimide resin molded body, and more particularly to improvement in processing dimensional accuracy of a polyimide resin molded body.
[0002]
[Prior art]
TAB, CSP, etc., which are known as IC and LSI mounting parts, are made of a so-called copper polyimide substrate with a copper film laminated on the surface of a polyimide resin film molded with a polyimide resin. , And by performing an etching treatment of the polyimide resin film.
[0003]
On the other hand, along with the recent downsizing and thinning of portable electronic devices, it is natural that the above-mentioned TAB, CSP, etc. are also required to be small and thin, that is, high density, and the processing dimensions are extremely High dimensional accuracy is required.
[0004]
Etching of the polyimide resin film described above is generally performed by forming a metal film such as copper or an organic resist on the polyimide resin film surface as an etching resist, and dissolving the exposed polyimide resin film with an alkaline solution or the like. It is used for.
[0005]
This method is widely used as a method for manufacturing conventional TAB, CSP, and the like. However, as mentioned above, when a higher density and a very high dimensional accuracy with respect to the processing dimensions are required, the processing dimensions of the polyimide resin film satisfy the required accuracy in the conventional processing method. There was a problem that I could not.
[0006]
[Problems to be solved by the invention]
In order to solve the above problems, an object of the present invention is to provide a method for processing a polyimide resin that satisfies the extremely high dimensional accuracy required for a polyimide resin film in the above-described method for processing a polyimide resin.
[0007]
[Means for solving the problems]
To solve the above problems, first means of the present invention, in the processing method of the polyimide resin film is etched portions of the polyimide resin film of copper polyimide substrate laminated copper film on the surface of the polyimide resin film, A method for processing a polyimide resin film , comprising performing heat treatment at 300 ° C. to 500 ° C. for 10 minutes to 2 hours after forming the polyimide resin film and before laminating a copper film and before performing the etching process .
[0008]
In addition, the polyimide resin film processing method according to the first means , wherein the etching processing is selected from dissolution processing using an alkaline solution or laser processing .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
When the present inventors etched a polyimide resin film by a conventional method, the processing accuracy varies depending on the portion of the polyimide resin film, and the variation and the degree of distortion of the polyimide orientation in the polyimide resin film. It has been found that there is a correlation, and further, by applying an appropriate heat treatment to the polyimide resin film, the degree of orientation distortion can be relaxed and the above problems can be solved.
[0010]
That is, the present invention provides a method for processing a polyimide resin film and performing by etching a portion of the polyimide resin film of copper polyimide substrate laminated copper film on the surface of the polyimide resin film, said polyimide After molding the resin film , heat treatment is performed at 300 ° C. to 500 ° C. for 10 minutes to 2 hours before lamination of the copper film and before performing the etching process . Moreover, it is preferable to perform the said heat processing in the range with which the breaking strength of the polyimide resin film after heat processing hold | maintains 50% or more of the breaking strength before heat processing.
[0011]
In general, as a method of molding a polyimide resin film, a polyamic acid, which is a polyimide precursor, is melted in a polar high boiling point organic solvent such as DMAc (dimethylacetamide), cast on a metal support surface to be in a semi-cured state, and peeled off. However, there is known a method of accelerating solvent removal and imide condensation by performing a predetermined heat treatment to finally obtain a film-like molded body.
[0012]
In addition, for the purpose of strengthening the mechanical strength of the polyimide resin film, the film edge portion is used for the purpose of adjusting the thickness and width of the film so as to be stretched together with the heat treatment or to be molded as a film. In many cases, the mold is chucked with a jig or the like and supported by applying stress in the width direction.
[0013]
It is known that the orientation of the polyimide polymer in the polyimide resin film obtained by the above treatment is affected by the strength and direction of the stress applied during film molding, and the orientation is oriented in the stressed direction. ing.
For example, when biaxial stretching is performed, the orientation of the polyimide polymer is aligned with the direction of synthesis of biaxial stretching force with respect to MD (roll length direction) or TD (roll width direction), and the direction is the film. Depending on the TD position, the polyimide resin film MD that is continuously molded under the same conditions has almost the same tendency regardless of the position.
[0014]
On the other hand, when the polyimide resin film is etched as described above, for example, the copper film formed on the polyimide resin film surface is dissolved and removed in a circular shape using a photolithographic technique to expose the polyimide resin in that portion. After that, when a via hole is formed by etching a polyimide resin using a hydrazine monohydrate solution, the top part and bottom part of the via hole are almost circular at the center of the film TD, and especially the distortion is observed in the shape. Not.
[0015]
However, as it becomes the end at the TD position, the circle becomes an elliptical shape, the degree of deformation becomes remarkable, and the orientation of the major axis of the ellipse is almost the same direction regardless of the position in the MD of the polyimide resin film. It turned out to be suitable.
[0016]
From the above findings, a correlation was observed between the orientation of the polyimide polymer and the anisotropy of etching. Accordingly, the present inventors, in order to improve the dimensional accuracy when the etching of the polyimide resin film, a phenomenon in which the orientation of the polyimide polymer is biased in a certain direction by the site of a polyimide resin film, i.e., a distortion, a method of alleviating the As a result of this, as a result of diligent research focusing on applying heat treatment to the polyimide resin film before laminating the copper film and before performing the etching process, the above object is achieved by applying predetermined heat treatment. Found that can be achieved.
[0017]
The heat treatment performed in the present invention is influenced by the structure of the polyimide polymer, the thickness of the molded body, the heat treatment conditions required at the time of molding, the magnitude of the stress applied at the time of molding, etc. An appropriate heat treatment condition range may be obtained from the point of dimensional accuracy after etching processing, but generally, the dimensional accuracy of etching processing performed thereafter tends to be improved when heat treatment is performed at a high temperature for a long time.
[0018]
However, when the heat treatment is performed at a temperature far exceeding the glass transition point of polyimide or for a very long time, the mechanical properties of the polyimide resin film change and the expected properties are sufficiently obtained. The problem of disappearing occurs.
[0019]
Therefore, in the present invention, it is also found that the heat load applied to the substrate by the heat treatment is preferably in a range in which the breaking strength of the polyimide resin film after the heat treatment maintains 50% or more of the breaking strength before the heat treatment. It was. For example, polyimide resin films such as Kapton (manufactured by Toray DuPont) and NPI (manufactured by Kaneka Chemical) may be subjected to heat treatment at about 300 to 500 ° C. for about 10 minutes to 2 hours. Equivalent to.
[0020]
The present invention is not particularly limited to the polyimide etching method, and for the case of performing a melting process using hydrazine or an alkaline solution as described above, or the case of performing a laser process such as a carbon dioxide laser or an excimer laser. Widely effective and applicable.
[0021]
【Example】
Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0022]
Example 1 A Kapton EN molded to a thickness of 50 μm and a width of 1048 mm was used as a polyimide resin film, and a heat treatment was performed at 400 ° C. for 30 minutes in a nitrogen atmosphere. The breaking strength of the polyimide resin film before the heat treatment was 340 MPa (measured according to JIS C-2318), the breaking strength after the heat treatment was 300 MPa, and the retention rate of the breaking strength was 88%.
[0023]
Thereafter, a copper film having a thickness of 1 μm is formed on both surfaces of the film by plating, a resist layer having a thickness of 20 μm is formed on the copper surface, and the lead width at the narrowest portion is 20 μm and the lead interval is 20 μm on one surface. Then, after patterning the resist layer by photolithography, leads were formed by electroplating on the exposed copper surface as a plating resist.
[0024]
Thereafter, the plating resist layer is removed, and the other surface on which the lead is formed is patterned into a circle having a diameter of 200 μm by the same photolithography technique, and the copper plating film exposed as an etching resist is etched and removed. The 1 μm thick copper plating film exposed between them was removed by etching. Thereafter, the polyimide portion exposed in a circular shape with a diameter of 200μm on the other surface forming the lead dissolved by etching. Etching conditions were such that the etching solution was hydrazine monohydrate concentration: 800 ml / liter, anhydrous ethylenediamine concentration: 200 ml / liter, and the etching conditions were a temperature of 50 ° C. and a time of 5 minutes.
[0025]
As a result of observing the via hole portion formed in the polyimide resin film obtained by the above processing using a microscope, the via hole top portion is etched into a circular shape having a diameter of 210 μm and the via hole bottom portion having a diameter of 110 μm. Further, it was found that the shape and dimensions thereof hardly changed depending on the positions of the film MD and TD, and the polyimide resin was etched and processed uniformly and accurately over the entire surface of the film.
[0026]
(Example 2) Except that the heat treatment applied to the polyimide resin film was 500 ° C for 10 minutes, a copper lead was formed on one side of the polyimide resin film in accordance with the same procedure as in Example 1, and a via hole was formed from the opposite side. did. In addition, the breaking strength retention of the polyimide resin film after heat processing was 55%.
[0027]
As a result of observing the via hole portion formed in the polyimide resin film obtained by the above processing using a microscope, the via hole top portion is etched into a circular shape having a diameter of 210 μm and the via hole bottom portion having a diameter of 110 μm. In addition, it was found that the shape and dimensions thereof hardly changed depending on the positions of the films MD and TD, and the polyimide resin was etched and processed uniformly and accurately over the entire surface of the film.
[0028]
(Example 3) Except that the heat treatment applied to the polyimide resin film was 300 ° C for 2 hours, a copper lead was formed on one side of the polyimide resin film in accordance with the same procedure as in Example 1, and a via hole was formed from the opposite side. did. In addition, the breaking strength retention of the polyimide resin film after heat processing was 94%.
[0029]
As a result of observing the via hole portion formed in the polyimide resin film obtained by the above processing using a microscope, the via hole top portion is etched into a circular shape having a diameter of 210 μm and the via hole bottom portion having a diameter of 110 μm. In addition, it was found that the shape and dimensions thereof hardly changed depending on the positions of the films MD and TD, and the polyimide resin was etched and processed uniformly and accurately over the entire surface of the film.
[0030]
(Example 4) Thickness 50μm as polyimide resin film, according to the procedure analogous to Example 1 except for using the NPI which is molded in the width 1028Mm, the copper leads are formed on one surface of the polyimide resin film, from the opposite surface thereof A via hole was formed. In addition, the breaking strength retention of the polyimide resin film after heat processing was 83%.
[0031]
As a result of observing the via hole portion formed in the polyimide resin film obtained by the above processing using a microscope, the via hole top portion is etched into a circular shape having a diameter of 210 μm and the via hole bottom portion having a diameter of 130 μm. In addition, it was found that the shape and dimensions thereof hardly changed depending on the positions of the films MD and TD, and the polyimide resin was etched and processed uniformly and accurately over the entire surface of the film.
[0032]
(Example 5) Etching of the polyimide resin film in Example 1 was carried out by removing the exposed polyimide portion with a processing energy of 100 J / cm 2 and a shot number of 2 using a carbon dioxide laser, and forming a via hole. A similar procedure was followed.
[0033]
As a result of observing the via hole part formed in the polyimide resin film obtained by the above treatment using a microscope, the via hole top part is etched into a circular shape having a diameter of 200 μm and the via hole bottom part having a diameter of 180 μm. In addition, it was found that the shape and dimensions thereof hardly changed depending on the positions of the films MD and TD, and the polyimide resin was etched and processed uniformly and accurately over the entire surface of the film.
[0034]
(Comparative Example 1) Example 1, in accordance with the same procedure except that no heat treatment is carried out for the polyimide resin film, a copper lead is formed on one surface of the polyimide resin film, a via hole was formed from the opposite surface.
[0035]
As a result of observing the via hole portion formed in the polyimide resin film obtained by the above treatment using a microscope, the via hole top portion at the center of the TD of the polyimide resin film has a diameter of 210 μm and the via hole bottom portion has a diameter of 130 μm. It was confirmed that it was etched into a shape. On the other hand, according to the TD end at the same MD position, the shape of the via hole top and bottom becomes elliptical, and at the position of 480 mm from the center of the TD, the via hole top part has a long axis of 230 μm in the direction of 40 degrees with respect to MD, and An elliptical shape having a minor axis of 200 μm so as to be orthogonal to the major axis, and an elliptical shape having a minor axis of 130 μm in the direction of 40 degrees with respect to MD and a minor axis of 100 μm so that the via hole bottom is perpendicular to the major axis. It turned out that it was processed.
[0036]
This cannot be said that the polyimide is etched uniformly and accurately over the entire surface of the film, and lacks reliability when used as a mounting component such as TAB or CSP.
[0037]
(Comparative Example 2) According to the same procedure as in Example 1 except that the heat treatment applied to the polyimide resin film was 600 ° C for 10 minutes, a copper lead was formed on one side of the polyimide resin film, and a via hole was formed from the opposite side. did. In addition, the fracture strength retention of the polyimide resin film after heat treatment is 48%, and when this is used as a material for mounting parts such as TAB and CSP, reliability is insufficient.
[0038]
【The invention's effect】
According to the present invention, it is possible to process extremely uniform and high dimensional accuracy over the entire polyimide resin film , which has been difficult in the past, and mount components such as high density, high accuracy, and high reliability TAB and CSP. Obtainable.

Claims (1)

In the polyimide resin film processing method of etching a part of the polyimide resin film of the copper polyimide substrate having a copper film laminated on the surface of the polyimide resin film,
After the polyimide resin film is molded, before the copper film is laminated and before the etching process, a heat treatment is performed at a temperature of 300 ° C. to 500 ° C. for 10 minutes to 2 hours ,
A method for processing a polyimide resin film, wherein the breaking strength of the polyimide resin film after the heat treatment is maintained at 50% or more of the breaking strength before the heat treatment .