JP3251515B2 - Resin etching solution and etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin etching solution and an etching method.

[0002]

2. Description of the Related Art Hitherto, polyimide resins having various excellent properties such as heat resistance and electrical insulation have been widely used in the field of electronics. For example, it is used for a flexible printed board, a TAB tape, and the like.

[0003] The polyimide resin is used in various forms such as a film, a sheet, and a coating agent. However, in the case of a film, not only a single form but also a copper It is also used in the form of a so-called laminate, such as attaching a foil with an adhesive, performing copper sputtering-copper electrolytic plating, or casting or coating a polyimide resin on a copper foil.

[0004] For this reason, many such substrates are commercially available from related companies. For example, typical examples of the polyimide film alone include Kapton (trade name of DuPont, USA), Upilex R (trade name of Ube Industries, Ltd.), and Apical (trade name of Kanebuchi Chemical Co., Ltd.). .

[0005] Further, as typical examples of a product formed by casting a polyimide resin on a copper foil, Neoflex (trade name of Mitsui Toatsu Chemical Co., Ltd.) and Espanex (trade name of Nippon Steel Chemical Co., Ltd.) Name).

As typical examples of the coating agent, Trenice (trade name, manufactured by Toray Industries, Inc.), and as typical examples of the polyimide bonding sheet, UPA (trade name, manufactured by Ube Industries, Ltd.) and SPB (Nippon Steel Chemical Co., Ltd.) Co., Ltd.).

[0007] Among the polyimide resins used in various forms, a polyimide film used as a base material of a circuit board is provided with through holes and device holes. In general, a hole is formed by a chemical etching method, and at this time, an alkali-hydrazine-based etchant is used.

That is, for example, Japanese Patent Application Laid-Open No. Hei 3-10122
No. 8 discloses an etchant comprising hydrazine monohydroxide and potassium hydroxide, or disclosed in JP-A-5-202206.
An etching solution containing sodium hydroxide, ethylenediamine, hydrazine monohydrate, dimethylamine solution, and N, N-dimethylformamide is used.

[0009]

However, since such a hydrazine-based etching solution has toxicity (possibly carcinogenicity) and a short life, it is necessary to pay close attention to solution management. Therefore, it is difficult to perform the etching under the optimum condition.

In addition, such a hydrazine-based etchant easily penetrates into the interface between the polyimide film and a mask used to form holes of a predetermined shape, and is therefore particularly formed by laminating a polyimide film and a copper foil. In the case of a substrate, when an attempt is made to etch using a patterned copper foil as a mask, the copper foil and the polyimide film are peeled off before the polyimide film is etched to form a through hole (etching hole). However, there is also a disadvantage that a situation in which it is difficult to form an etching hole is likely to occur.

[0011] Incidentally, other etching liquid, for example, disclosed in Japanese Patent Public Sho 60-14776 discloses, but are also used etching solution or the like consisting of urea and an alkali metal compound, the etching solution, the former In comparison with the above, the etching rate is remarkably inferior, the shape of the etching hole is easily deformed (the shape and dimensions are not predetermined),
If the etching temperature is set to a higher temperature in order to increase the etching rate, urea is decomposed and ammonia with a strong irritating odor is generated, which is a problem in environmental hygiene.

Further, any of these conventional etching solutions can etch a polyimide film (for example, the Kapton or the Apical) obtained by polycondensation of pyromellitic dianhydride and an aromatic diamine. Even, compared to that kind of polyimide film, it is excellent in dimensional stability and chemical resistance at the time of heating, and is suitable for forming a finer circuit pattern, and a biphenyltetracarboxylic dianhydride and diaminobenzene are preferred. The polyimide film obtained by the polycondensation, for example, has a fatal defect that etching of a UPIREX S (trade name of Ube Industries, Ltd.) is difficult.

Therefore, for example, a two-layer polyimide film comprising a copper foil and the above-mentioned Upilex S is provided with a diameter of 200 mm.
For example, when a fine through-hole of submicron or less is to be formed, processing by an expensive excimer laser method or the like is unavoidable, and a solution to this point has been strongly desired.

In addition to the above-mentioned etching solution,
For example, [0068] of JP-A-7-157560
Dimethylformamide solution containing ethanolamine, which is difficult to etch with respect to an organic solvent-insoluble polyimide resin, and the Kapton, which is an organic solvent-insoluble polyimide film. And the above-mentioned ubilex cannot be used.

The present invention has been made in view of the above, and is not limited to etching of a polyimide resin obtained by polycondensation of pyromellitic dianhydride and an aromatic diamine, but also biphenyl. An etching solution suitable for etching of a polyimide resin obtained by polycondensation of tetracarboxylic dianhydride and diaminobenzene, and a method for quickly and satisfactorily etching a film composed of such a resin. As a result of intensive studies to provide an etching method capable of achieving the above, an etching solution containing an oxyalkylamine and an alkali metal compound was found, and the present invention was completed.

[0016]

That is, one of the resin etching solutions according to the present invention contains at least an oxyalkylamine and an alkali metal compound in an etching solution for a polyimide resin. It is characterized by doing.

Further, another one of the resin etching solutions according to the present invention comprises a polyimide resin
The etchant for use in the present invention is characterized in that it contains urea in addition to the oxyalkylamine and the alkali metal compound.

Further, another one of the resin etching solutions according to the present invention comprises a polyimide resin
The etching solution for use in the present invention contains an organic polar solvent in addition to the oxyalkylamine and the alkali metal compound.

According to a fourth aspect of the present invention, there is provided a resin etching liquid according to the present invention, wherein the oxyalkylamine comprises a first oxyalkylamine. One of a secondary amine and a secondary amine or a mixture thereof.

According to another aspect of the present invention, in the resin etching solution according to the fourth aspect, the primary amine is ethanolamine, propanolamine. , Butanolamine or N (β-aminoethyl) ethanolamine, and the secondary amine is diethanolamine, dipropanolamine, N-methylethanolamine or N-ethylethanolamine. .

Further, another one of the resin etching solutions according to the present invention is, as described in claim 6, claim 1, 2, 3, or 4;
The resin etching solution according to 3, 4, or 5, wherein the alkali metal compound is any one of potassium hydroxide, sodium hydroxide, and lithium hydroxide or a mixture thereof.

According to a seventh aspect of the present invention, there is provided an etching method according to the first to third aspects.
A polyimide film having a resist pattern formed on both surfaces or one surface is etched using the resin etching solution described in 4, 5, or 6.

Another aspect of the etching method according to the present invention is as described in claim 8.
Using the resin etching solution described in 3, 4, 5, or 6,
The method is characterized in that a polyimide film having a metal layer pattern having the same shape as a resist pattern formed on both surfaces or one surface is etched.

Another aspect of the etching method according to the present invention is the polyimide film immersed in a resin etching solution in the etching method according to claim 7 or 8. It is characterized by irradiating the substrate with ultrasonic waves and etching.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The resin etching solution according to the present invention contains at least an oxyalkylamine and an alkali metal compound, and the oxyalkylamine contains a water-soluble compound having an amino group and an alcoholic hydroxyl group in the same molecule. Either primary or secondary amines or mixtures thereof are used.

The primary amine may be ethanolamine, propanolamine such as n-propanolamine or isopropanolamine, butanolamine such as n-butanolamine or 2-amino-1-butanol, or N (β- Aminoethyl) ethanolamine.

These are preferable because an economical etching rate can be obtained and the shape of the etching hole can be prevented. The etching hole may have any shape such as a circular shape and a square shape.

Further, examples of the secondary amine include diethanolamine, dipropanolamine, N-methylethanolamine and N-ethylethanolamine. These are inferior in etching properties to polyimide resins having excellent chemical resistance such as the above-mentioned Upilex S,
It is preferably used for pyromellitic acid-based polyimide resin such as Kapton because it is good.

As described above, the use of a primary or secondary amine and not the use of a tertiary amine having an alcoholic hydroxyl group, such as triethanolamine or tripropanolamine, is not economically efficient. This is not preferable because a proper etching rate cannot be obtained, and the polyimide resin may swell and a minute crack may be generated.

[0030] The concentration of oxyalkylated amine, 4% to 70% relative to the etching of sets formed aqueous solution may be any preferably 5% to 40%. If the concentration of the oxyalkylamine is too low, the etching rate is reduced, and if it exceeds 70% or more, the concentration of the alkali metal compound, which is another essential component, is reduced, and the etching rate is undesirably reduced.

In addition, potassium hydroxide is most preferable as the alkali metal water compound in terms of obtaining an economical etching rate, but other compounds such as sodium hydroxide and lithium hydroxide can be used, and These can be used alone or in combination.

The concentration is from 5%, and a saturated solution at the operating temperature is used. If the concentration is too low, the etching rate is reduced, and at the same time, the shape of the etching hole is deformed (the shape and dimensions are not predetermined). On the other hand, if the temperature is too low, there is a risk of clogging of pipes and the like when the temperature is lowered.
About 8% is preferable. Generally, from the viewpoint of obtaining an economical etching rate and preventing the shape of the etching hole from being lost, 20% to 45% is most preferable.

It is necessary to select an appropriate etching temperature according to the type of the polyimide resin to be etched. Generally, it is in the range from 20 ° C. to the boiling point of the system used, but is preferably from 30 ° C. to 90 ° C.

When the polyimide film is etched from one side, a taper is likely to occur as a difference between the upper and lower diameters of the penetrated etching hole. To reduce the taper, it is effective to add urea.

The etching rate does not change even if urea is added. In addition, since the decomposition is suppressed, the smell of ammonia can be reduced. This is because the etching agent according to the present invention using an oxyalkylamine can be used under milder conditions than a conventional hydrazine-based etching solution.

Further, by adding and mixing an organic polar solvent to the etching solution, the wall surface of the etching hole can be made smooth and the etching residue can be removed. Therefore, it is preferable to mix as needed. As such an organic polar solvent, N-methyl-2-pyrrolidone (NMP) is suitable. Note that both urea and an organic polar solvent may be added.

The resin etching solution according to the present invention comprises:
Although it can be used not only for a film body but also for any form of polyimide resin, it is preferably used for a film body.

If necessary, it may be used for resins other than the polyimide resin. However, it is preferable to use a polyimide resin, especially a polycondensation of biphenyltetracarboxylic dianhydride or an ester thereof with diaminobenzene. Obtained, for example, polyimide resin having excellent heat resistance, dimensional stability and chemical resistance such as the above-mentioned Upilex S, that is, etching was difficult with a conventional hydrazine-based etchant or an alkali-urea-based etchant. Polyimide resin is preferentially selected.

However, other polyimide resins, for example, polyimide resins obtained by polycondensation of pyromellitic dianhydrides and aromatic diamines (for example, Kapton and Apical, etc.) can also be used in the conventional etching described above. Compared to etching with liquid, under milder conditions
This is preferable because etching can be favorably performed in a short time.

The polyimide film to be etched using the resin etching solution according to the present invention may be a polyimide film having a resist pattern formed on both sides or one side, or a metal layer pattern having the same shape as the resist pattern on both sides or one side. Any of the formed polyimide films may be used.

That is, in the former case, a polyimide film having a resist pattern formed directly on the film surface is used. In the latter case, a resist pattern is formed by interposing a metal layer such as copper on the film surface. Is used, and in any case, a predetermined etching hole can be formed by etching the exposed film portion.

In this case, it is preferable to perform etching while irradiating an ultrasonic wave or to spray an etching solution to an etching portion through a nozzle (preferably a spray nozzle). This is because the etching by such a method can shorten the etching time and facilitate the operation of forming a fine pattern.

In order to avoid the deterioration of the etching solution, the ultrasonic type is more preferable than the nozzle type. In the case of the ultrasonic type, an ultrasonic oscillator and / or a propeller type or a jet type is used. The object to be etched may be immersed in an etching solution in a processing tank equipped with a stirrer. At that time, only ultrasonic irradiation or only stirring may be performed, but it is most preferable to perform ultrasonic irradiation and stirring together.

This is because the shape of the etching hole can be prevented from being deformed and the taper can be further reduced. It should be noted that performing only ultrasonic irradiation is more effective in preventing the shape of the etching hole from being deformed than performing only stirring.

FIG. 1 shows an ultrasonic etching mode. An etching object 3 (for example, a polyimide film specimen) is added to an etching solution 2 in a processing tank 1.
Is immersed, and ultrasonic waves are emitted from the ultrasonic oscillator 4 mounted on the bottom of the tank. The etching liquid 2 is heated by a heater 6 to be maintained at a predetermined liquid temperature and is stirred by a propeller type stirring device 5.

Therefore, various forms of polyimide resin can be favorably etched using the resin etching solution according to the present invention. For example, it is suitable for a metal-based semiconductor package.

Such a semiconductor package is electromagnetically shielded and can be mounted with good heat dissipation, so that it is suitable for high-density mounting, and includes a mounted semiconductor chip, a conductor circuit, and a plurality of external connections. It is composed of a metal substrate in which terminals and necessary portions are covered with an insulating layer, and one or more such insulating layers are formed, and a conductor circuit is formed on each insulating layer.

For this reason, a polyimide film is suitable as a material for forming the insulating layer, and it is necessary to form a through hole or a via hole in the polyimide film. Through holes and the like can be economically etched while preventing shape loss.

Also, in a printed circuit board comprising a conductor circuit, a plurality of external connection terminals and an insulating layer, one or more such insulating layers are formed and a conductor circuit is formed on each insulating layer. Therefore, polyimide film is considered to be suitable as the constituent material,
ADVANTAGE OF THE INVENTION According to the resin etching liquid which concerns on this invention, while etching through holes etc. can be prevented from deforming, it can be economically etched.

As is well known, printed wiring circuit boards for high-density mounting are manufactured by various methods, that is, a fine wiring pattern formed on a conductive substrate by electrolytic plating is formed on a metal sheet. A thermal pattern is transferred from the conductive substrate onto an insulating layer made of a polyimide film, or a wiring pattern is formed by a photoetching method on the copper foil of a substrate obtained by laminating a copper foil on an insulating layer formed on a metal sheet. Or, furthermore, it is manufactured by a method such as forming a copper thin film on an insulating layer formed on a metal sheet by a sputtering method and then forming a wiring pattern by a photoplating method. According to the liquid, the polyimide film used for them can be favorably etched as described above.

A polyimide film obtained from biphenyltetracarboxylic dianhydride and diaminobenzene, such as Iupirex S, which has excellent heat resistance, dimensional stability and chemical resistance, has one or more insulating layers. Layer and a conductor circuit formed on each insulating layer.
It is suitable as a material for forming such an insulating layer of AB tape, and it is strong even in a thin film of 75 microns or less and has excellent dimensional stability. However, according to the resin etching solution according to the present invention, it is possible to etch such a polyimide film, and conventionally, it is difficult to form through holes and device holes, which are difficult, while preventing their shape from being lost. Can be etched.

[0052]

【Example】

Example 1 A 50 μm thick polyimide film manufactured by Ube Industries, Ltd., that is, a 10 mm × 5 mm test piece was prepared from Upilex S, and an etching solution 100 containing ethanolamine and potassium hydroxide was prepared.
g. At this time, the dissolution rate of the test piece was measured by varying the concentrations of potassium hydroxide and ethanolamine contained in the etching solution, and the results are shown in FIG.

At an ethanolamine concentration of 3%, the upilex S did not dissolve, and at 5%, it began to dissolve almost without swelling, and the film thickness was reduced. Further, the dissolution rate became higher as the concentrations of potassium hydroxide and ethanolamine were higher.

[Examples 2 to 4] ... Metaroyal film manufactured by Toyo Metallizing Co., Ltd. (a polyimide film having a thickness of 50 microns manufactured by Ube Industries, Ltd.,
A product having a 8 μm copper foil formed on one surface of the above-mentioned IUPIREX S) is coated with 7 μm of a positive type resist PMER manufactured by Tokyo Ohka Co., Ltd., dried and subjected to ultraviolet exposure and alkali development to obtain a 150 μm diameter. A resist pattern in which micron holes were arranged at intervals of 200 microns was formed.

Next, the exposed copper foil was etched with an etching solution containing ferric chloride to form a copper foil pattern having the same shape as the resist pattern. After that, a PET-based masking tape was stuck on the surface of the metal royal film on which the copper foil was not formed, and then 80 ° C. using an etching solution having a different concentration.
To perform polyimide etching. Table 1 shows the results.

[0056]

[Table 1] Example 5 Etching was performed under the same conditions as in Example 3 except that isopropanolamine was used instead of ethanolamine. As a result, good etching holes could be obtained.

Example 6: Etcherflex manufactured by Mitsui Toatsu Chemicals, Inc. (thickness 12 manufactured by DuPont, USA)
On both surfaces of a 5 micron Kapton V, a positive resist PMER manufactured by Tokyo Ohka Co., Ltd. was applied and dried on both surfaces of the copper foil of an 18 micron copper foil, and was subjected to ultraviolet exposure and alkali development. A resist pattern in which holes having a diameter of 150 microns were arranged at intervals of 200 microns was formed. Next, the exposed copper foil was etched with an etching solution containing ferric chloride to form a copper foil pattern having the same shape as the resist pattern.

In an etching solution comprising 50% of diethanolamine, 25% of potassium hydroxide and 25% of water,
When the etcher flex film on which the pattern was formed was immersed and etched at 60 ° C. for 5 minutes while oscillating, an etched through hole having the same size and the same shape and a good edge as the copper pattern was obtained.

Example 7 Etching was performed under the same conditions as in Example 6 except that dipropanolamine was used in place of diethanolamine. A good edge having the same dimensions and the same shape as the copper pattern was obtained. Was obtained.

Example 8: 50% ethanolamine
The metalloyal film (the one used in Examples 2 to 4) was etched at 80 ° C. for 20 minutes using an etching solution equipped with an ultrasonic oscillator using an etching solution composed of 25% potassium hydroxide and 25% water. However, an etched through hole having the same dimensions as the copper pattern and having a well-shaped edge was obtained.

Example 9: 50% ethanolamine,
The etcher flex film prepared under the same conditions as in Example 6 was set in an etching apparatus equipped with an ultrasonic oscillator using an etching agent composed of 25% of potassium hydroxide and 25% of water, and etched at 80 ° C. for 3 minutes. As a result, an etched through hole having an edge having the same size and shape as the copper pattern was obtained.

Example 10 Ethanolamine 30
%, Potassium hydroxide 17%, N-methylpyrrolidone 16
%, Urea 20%, and water 17%, except that etching was performed at 70 ° C. for 8 minutes under the same conditions as in Example 9 to obtain an etching through having a good shape. A hole could be obtained.

Example 11 Ethanolamine 36
%, Urea 24%, potassium hydroxide 20%, and water 20%, and etching was performed under the same conditions as in Example 9 except that etching was performed at 70 ° C. for 6 minutes and 30 seconds. Etching through-holes of various shapes could be obtained.

[0064]

[Comparative example]

Comparative Example 1 Etching was performed under the same conditions as in Example 4 except that hydrazine was used instead of ethanolamine. When the treatment was performed for 20 minutes, peeling occurred between the copper foil and the polyimide film, and the polyimide film was also etched, but an etching through hole having a predetermined shape was not obtained.

When the etching time was shortened to 4 minutes, the polyimide film was not etched despite the peeling between the copper foil and the polyimide film. As described above, the etching was performed while changing the temperature and time in various ways, but no conditions for obtaining a good etching through hole could be found.

Comparative Example 2 An etching solution described in Example 3 of JP-A-3-101228,
That is, hydrazine monohydrate / potassium hydroxide = 10
Etching was performed under the same conditions as in Example 4 except that this etching solution was used using 0 / 18.7 (parts by weight), and peeling occurred between the copper foil and the polyimide film. Other portions of the polyimide were also dissolved, so that it was not possible to find conditions that allowed the holes to penetrate the polyimide film satisfactorily.

Comparative Example 3 An etching solution described in Example 4 of JP-A-5-202206, that is, 70% by volume of a 40% aqueous solution of sodium hydroxide, 8% by volume of hydrazine monohydrate, and ethylenediamine 20
% Aqueous solution 22 vol%, dimethylamine solution 12 vol
The metal royal film having a pattern formed on the surface of the copper foil prepared in Example 2 was etched at 75 ° C. using an etching solution containing 1% and 12 vol% of N, N-dimethylformamide. It was not possible to find a condition under which holes could be satisfactorily penetrated through the polyimide film so that peeling between the polyimide films did not occur.

Comparative Example 4 A metalloyal film having a pattern formed on the surface of a copper foil was etched at 80 ° C. under the same conditions as in Example 4 except that diethanolamine was replaced with urea. Etching time 30
In spite of the fact that peeling began to occur at the interface between the polyimide film and the copper foil pattern in a minute, the etching was not performed. After 45 minutes, the peeling further proceeded, but the etching of the polyimide film was not sufficient, and as a result, the holes could not be satisfactorily penetrated through the polyimide film.

[0069]

As described above, according to the present invention, not only polyimide resin obtained by polycondensation of pyromellitic dianhydride and aromatic diamine but also biphenyltetracarboxylic dianhydride and diaminobenzene Polyimide resin obtained by the polycondensation of can be satisfactorily etched, it is possible to obtain a versatile resin etching solution and among various types of resins, particularly, an etching method suitable for etching a polyimide film Is obtained.

In addition, during etching, an economical etching rate can be obtained, the shape of the etching hole can be prevented from being deformed (the shape and dimensions are not in a predetermined state), and the tapering of the etching hole can be further reduced. It can be made even smaller and its wall surface (hole peripheral surface) can be made smooth.

At the time of etching, the generation of ammonia having a strong pungent odor can be reduced, and the problem of environmental hygiene can be solved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an ultrasonic etching mode.

FIG. 2 is a diagram showing the relationship between the concentrations of potassium hydroxide and ethanolamine and the dissolution rate of a polyimide film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing tank 2 Etching liquid 3 Etching object 4 Ultrasonic oscillator 5 Stirrer 6 Heater

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masanori Akita 1-1-45 Oe, Otsu City, Shiga Prefecture Examiner, Toray Engineering Co., Ltd. Yoshiko Maeda (56) References JP-A-4-219933 (JP, A) JP-A-6-234870 (JP, A) JP-A-4-20539 (JP, A) JP-A-4-15233 (JP, A) JP-A-6-302586 (JP, A) JP-A-5-202206 (JP, A) JP-A-5-283486 (JP, A) JP-A-1-120557 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/40 C08J 7 / 00 H05K 3/00 C08J 7/12 H05K 3/06

Claims (9)

(57) [Claims] 1. An etching solution for a polyimide resin.
Te, the resin etching solution, characterized by containing at least oxyalkylated amines and alkali metal compounds. 2. The resin etching solution according to claim 1, further comprising urea in addition to the oxyalkylamine and the alkali metal compound. 3. The resin etching solution according to claim 1, further comprising an organic polar solvent in addition to the oxyalkylamine and the alkali metal compound. 4. The resin etching solution according to claim 1, wherein the oxyalkylamine is one of a primary amine and a secondary amine or a mixture thereof. 5. The method according to claim 1, wherein the primary amine is ethanolamine, propanolamine, butanolamine or N (β-aminoethyl) ethanolamine, and the secondary amine is diethanolamine, dipropanolamine, N
The resin etching solution according to claim 4, wherein the resin etching solution is -methylethanolamine or N-ethylethanolamine. 6. The method according to claim 1, wherein the alkali metal compound is any one of potassium hydroxide, sodium hydroxide and lithium hydroxide or a mixture thereof. Resin etchant. 7. An etching method comprising etching a polyimide film having a resist pattern formed on both surfaces or one surface using the resin etching solution according to claim 1, 2, 3, 4, 5, or 6. 8. A method for etching a polyimide film having a metal layer pattern having the same shape as a resist pattern on both surfaces or one surface using the resin etching solution according to claim 1, 2, 3, 4, 5, or 6. Characteristic etching method. 9. The etching method according to claim 7, wherein the polyimide film immersed in the resin etching solution is irradiated with ultrasonic waves to perform etching.