JP6111035B2 - Method for surface modification of ceramics - Google Patents
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Description
本発明は、絶縁性であるセラミックス材料の表面に、電極や回路となりうる導電部を形成する方法に関する。詳しくは、金属酸化物系セラミックスから酸素を除去し、その表面の所定の箇所に金属単体部分をパターン状に形成する、セラミックスの表面改質方法に関する。 The present invention relates to a method of forming a conductive portion that can be an electrode or a circuit on the surface of an insulating ceramic material. More specifically, the present invention relates to a ceramic surface modification method in which oxygen is removed from a metal oxide ceramic and a single metal portion is formed in a pattern at a predetermined portion of the surface.
従来、セラミックスの表面に導電部を形成する方法としては蒸着法やスパッタ法が用いられた。導電部を所定のパターン形状とするには、マスクを用意して不要部分への金属層形成を防ぐか、あるいはセラミックスの表面全体に金属層を形成した後エッチングによって不要部分の金属を除去するといった方法がとられる。他の方法としては、導電性ペーストを印刷した後焼成して導電パターンを形成する方法、めっき触媒を含むインクを用いて印刷した後めっきを実施して導電パターンを形成する方法などがあげられる。 Conventionally, a vapor deposition method or a sputtering method has been used as a method for forming a conductive portion on a ceramic surface. In order to make the conductive portion have a predetermined pattern shape, a mask is prepared to prevent formation of a metal layer on the unnecessary portion, or a metal layer is formed on the entire surface of the ceramic and then the unnecessary portion of the metal is removed by etching. The method is taken. Other methods include a method of forming a conductive pattern by printing a conductive paste and printing, and a method of forming a conductive pattern by performing plating after printing using an ink containing a plating catalyst.
しかしながらこれらの方法ではパターンの精度に問題があり、微細なパターンを形成するのは困難であった。マスクを用いた蒸着法やスパッタ法では、セラミックス基材とマスクとの間に隙間があった場合は導電パターンにズレやにじみが出来て正確なパターンが得られない。セラミックス表面の全面に金属層を形成した後エッチングによって不要部分を除去してパターンを形成する方法においても、エッチングの条件が強すぎた場合には残すべき導電パターン部を浸蝕してしまう虞がある。導電性ペーストやめっき触媒を含むインクによって印刷する方法では、印刷精度の限界や、その後のめっき処理によるパターンの拡大から、微細パターンの形成は困難であった。更に、導電パターンを形成するために複数の工程を必要とする煩雑さがあった。 However, these methods have a problem in pattern accuracy, and it is difficult to form a fine pattern. In a vapor deposition method or a sputtering method using a mask, if there is a gap between the ceramic substrate and the mask, the conductive pattern can be displaced or smeared, and an accurate pattern cannot be obtained. Also in the method of forming a pattern by removing unnecessary portions by etching after forming a metal layer on the entire surface of the ceramic surface, there is a risk of eroding the conductive pattern portion to be left if the etching conditions are too strong. . In the method of printing with an ink containing a conductive paste and a plating catalyst, it is difficult to form a fine pattern due to the limit of printing accuracy and the expansion of the pattern by subsequent plating treatment. Furthermore, there is a complexity that requires a plurality of steps to form a conductive pattern.
これらの問題を解消する方法として、特許文献１には、セラミックス材料の表面に対して、所定パターンに対応したマスクを介してエネルギー的にセラミックス材料の内殻電子を励起させることが可能な高輝度短波長光ビームまたはそれとエネルギー的に等価な電子ビームを照射することを特徴とするセラミックスの改質加工方法が開示されている。これによりセラミックス材料の表面部に原子の内殻電子の励起に基づく反応を生ぜしめ、酸素原子または窒素原子あるいは炭素原子を脱離させ、導電部を形成することができる。 As a method for solving these problems, Patent Document 1 discloses a high brightness capable of energizing inner shell electrons of a ceramic material energetically through a mask corresponding to a predetermined pattern on the surface of the ceramic material. A ceramic modification method characterized by irradiating a short wavelength light beam or an electron beam energetically equivalent to it is disclosed. As a result, a reaction based on the excitation of the inner core electrons of the ceramic material is caused on the surface portion of the ceramic material, and an oxygen atom, a nitrogen atom, or a carbon atom is desorbed to form a conductive portion.
また、特許文献２や３には、非酸化性雰囲気中でセラミックス表面にレーザー等のエネルギー線を照射して導電部を形成する方法が記載されている。これらの方法によれば、エネルギー線を照射するという工程のみでセラミックス表面に導電パターンを形成できるという利点を有し、高精度に微細なパターンを形成できるというメリットがある。 Patent Documents 2 and 3 describe a method of forming a conductive portion by irradiating a ceramic surface with an energy beam such as a laser in a non-oxidizing atmosphere. According to these methods, there is an advantage that a conductive pattern can be formed on the ceramic surface only by a process of irradiating energy rays, and there is an advantage that a fine pattern can be formed with high accuracy.
しかしながら、上記方法で得られる導電部については、十分な導電性を示すものを得られていないのが実情である。そのため、上記方法にて導電部を形成した後、更にめっき処理を行うことによってより確実な導電層を積層させる方法がとられている。 However, as for the electroconductive part obtained by the said method, what is showing sufficient electroconductivity is the actual condition. Therefore, after forming a conductive part by the said method, the method of laminating a more reliable conductive layer by performing a plating process is taken.
そこで本発明が解決しようとする課題は、レーザー照射工程のみで十分な導電性を有する導電部をセラミックス表面に形成することが可能なセラミックスの表面改質方法を提供することにある。 Therefore, the problem to be solved by the present invention is to provide a ceramic surface modification method capable of forming a conductive portion having sufficient conductivity on the ceramic surface only by the laser irradiation step.
前記課題を解決するため、本発明者は鋭意研究を重ねた結果、セラミックスの改質部分を特定の被覆剤で覆った状態でレーザー照射することで、高い導電性を有する導電部を形成できることを見出し、本発明を完成するに至った。 In order to solve the above-mentioned problems, the present inventor has conducted extensive research, and as a result, a conductive portion having high conductivity can be formed by irradiating a laser with the modified portion of the ceramic covered with a specific coating agent. The headline and the present invention were completed.
すなわち、本発明は、セラミックス表面にレーザー照射をすることによって導電部を形成するセラミックスの表面改質方法であって、改質すべきセラミックス表面部分を被覆剤で覆った状態で、波長３００ｎｍ〜９００ｎｍのレーザーを照射する工程を有する、セラミックスの表面改質方法である。
That is, the present invention is a ceramic surface modification method for forming a conductive portion by irradiating a ceramic surface with a laser, wherein the ceramic surface portion to be modified is covered with a coating agent and has a wavelength of 300 nm to 900 nm. A method for surface modification of ceramics, comprising a step of irradiating a laser.
前記被覆剤は照射するレーザーに対し、透明であることが好ましい。また、前記被覆剤は液体状被覆剤であって、セラミックス基材がこの液体に浸漬された状態でレーザー照射されてもよい。前記液体状被覆剤は水、酢酸、アルコール類、アセトンから選ばれる１種あるいは２種以上の混合物であってもよい。 The coating agent is preferably transparent to the irradiating laser. Moreover, the said coating agent is a liquid coating agent, Comprising: Laser irradiation may be performed in the state in which the ceramic base material was immersed in this liquid. The liquid coating agent may be one or a mixture of two or more selected from water, acetic acid, alcohols, and acetone.
本発明のセラミックスの表面改質方法によれば、レーザー照射工程のみでセラミックス表面に高精度に、高い導電性を有する導電部の微細パターンを形成することができる。 According to the ceramic surface modification method of the present invention, a fine pattern of a conductive portion having high conductivity can be formed on the ceramic surface with high accuracy only by a laser irradiation step.
本発明のセラミックスの表面改質方法は、特に金属酸化物系のセラミックスの表面改質に適しており、例えばアルミナ、酸化チタン、酸化亜鉛、酸化マグネシウム、ジルコニア、酸化スズ、酸化銅などのセラミックスに対して利用できる。
The surface modification method for ceramics according to the present invention is particularly suitable for surface modification of metal oxide ceramics. For example, for ceramics such as alumina, titanium oxide, zinc oxide, magnesium oxide, zirconia, tin oxide, and copper oxide. Available against.
使用できるレーザーは光源としてＹＡＧレーザー、チタンサファイアレーザー、Ｙｂファイバーレーザー、半導体レーザー、色素レーザーなどが挙げられ、そのエネルギーは１Ｗから２００Ｗであることが好ましい。エネルギーが１Ｗ未満ではセラミックス基板の改質が充分に行えないという問題があり、エネルギーが２００Ｗを超えるとセラミックス基材自体が損傷するという問題がある。また、レーザーの発振波長としては３００ｎｍから９００ｎｍであることが好ましい。この範囲より短波長あるいは長波長の場合、レーザー光が液状被覆物に吸収されてしまい、セラミックス基板の改質を効率よく行えないという問題がある。 Examples of the laser that can be used include a YAG laser, a titanium sapphire laser, a Yb fiber laser, a semiconductor laser, and a dye laser, and the energy is preferably 1 W to 200 W. If the energy is less than 1 W, there is a problem that the ceramic substrate cannot be sufficiently modified. If the energy exceeds 200 W, the ceramic base material itself is damaged. The laser oscillation wavelength is preferably from 300 nm to 900 nm. When the wavelength is shorter or longer than this range, the laser beam is absorbed by the liquid coating, and there is a problem that the ceramic substrate cannot be modified efficiently.
本発明ではセラミックス基材の表面を被覆剤で覆った状態とし、その被覆剤で覆われたセラミックス基材の表面部分に上記レーザーを照射させることで導電部を形成する。被覆剤の介在によって高い導電性を発現することができるが、そのメカニズムについては不明である。ひとつの可能性としては、金属酸化物系セラミックスからレーザー照射によって酸素原子を除去するにあたり、介在する被覆剤が除去される酸素原子を効果的に捕集するような働きをするものと推測される。 In the present invention, the surface of the ceramic substrate is covered with a coating agent, and the conductive portion is formed by irradiating the surface portion of the ceramic substrate covered with the coating agent with the laser. High conductivity can be expressed by the intervention of the coating agent, but the mechanism is unknown. One possibility is that when removing oxygen atoms from metal oxide ceramics by laser irradiation, the intervening coating agent is supposed to work to effectively collect oxygen atoms that are removed. .
このような被覆剤としては、前記レーザーに対して透明であることが好ましい。透明でない場合、すなわちレーザーを吸収、散乱する場合には発熱による蒸散が起きたり、レーザーのエネルギーが奪われたりすることとなり効率が低下する。 Such a coating agent is preferably transparent to the laser. If it is not transparent, that is, if it absorbs and scatters the laser, transpiration due to heat generation occurs or the energy of the laser is deprived and efficiency is reduced.
また、被覆剤は液体であることが好ましい。液体状被覆剤であると改質されるべきセラミックスの表面を容易に覆うことができる。また、セラミックス基材を液体状被覆剤に浸漬させた状態でレーザー照射することも可能である。 The coating agent is preferably a liquid. If it is a liquid coating agent, the surface of the ceramic to be modified can be easily covered. It is also possible to irradiate a laser with the ceramic substrate immersed in a liquid coating material.
被覆剤の厚みは１．５ｍｍ以下が好ましく、０．５ｍｍ以上１．５ｍｍ以下であることがより好ましい。１．５ｍｍを超える場合、均一にレーザー改質を行うことが困難となり、０．５ｍｍ未満の場合、被覆層の維持が困難となる。 The thickness of the coating agent is preferably 1.5 mm or less, and more preferably 0.5 mm or more and 1.5 mm or less. When it exceeds 1.5 mm, it is difficult to uniformly modify the laser, and when it is less than 0.5 mm, it is difficult to maintain the coating layer.
被覆剤として好適に用いられるのは水、酢酸、アルコール類、アセトンである。これらを単独で用いてもよいし、２種類以上を混合して使用してもよい。また、添加剤として増粘材、酸化防止剤、還元剤などを添加してもよい。添加剤を加える場合はレーザー発振波長に吸収がないものを用いることが好ましい。 Water, acetic acid, alcohols and acetone are preferably used as the coating agent. These may be used alone or in combination of two or more. Moreover, you may add a thickener, antioxidant, a reducing agent, etc. as an additive. In the case of adding an additive, it is preferable to use one having no absorption at the laser oscillation wavelength.
基材は、酸化チタン粉末（高純度化学研究所製、ＴＩＯ１４ＰＢ）を４０ＭＰａで圧縮成型し電気炉に投入した後、５時間かけて１２００℃まで昇温、５時間維持し、５時間かけて室温まで降温させて作製した。また、レーザーにはパルス発振ＹＡＧレーザー（５３２ｎｍ）（ＭｅｇａＯｐｔｏ社製、モデル名：高繰り返しパルスグリーンレーザー 型番：＃３０１−０１）を用いた。被覆剤としてのエタノールに酸化チタンセラミックスを浸漬させ、繰り返し周波数３５ｋＨｚ、出力１．２Ｗ、走査速度１２００ｍｍ／ｍｉｎにて走査長１１ｍｍ、走査回数２５０回、ピッチ５μｍでレーザー照射をおこない、幅１．２５ｍｍの直線パターンの導電部を酸化チタンセラミックス表面に形成した。このとき、酸化チタンセラミックス上方のエタノールの厚さ、すなわちレーザーの透過経路におけるエタノールの厚さは１ｍｍであった。導電性の評価は、直線導電パターンの両端間の抵抗値をデジタルハイテスター ３２５６−５０（日置電機株式会社製）にて測定した。抵抗値が小さいほど導電性が高いことをあらわす。得られた導電部の抵抗値は３．７×１０３ｋΩであった。 The substrate was compression-molded with titanium oxide powder (manufactured by High Purity Chemical Laboratory, TIO14PB) at 40 MPa and charged into an electric furnace, then heated to 1200 ° C. over 5 hours, maintained for 5 hours, and room temperature over 5 hours. It was made to cool down to. In addition, a pulsed YAG laser (532 nm) (manufactured by MegaOpto, model name: high repetition pulse green laser, model number: # 301-01) was used as the laser. Titanium oxide ceramics are immersed in ethanol as a coating agent, laser irradiation is performed at a repetition frequency of 35 kHz, an output of 1.2 W, a scanning length of 11 mm, a scanning frequency of 250 times, a pitch of 5 μm, and a width of 1.25 mm. The conductive part of the linear pattern was formed on the titanium oxide ceramic surface. At this time, the thickness of ethanol above the titanium oxide ceramics, that is, the thickness of ethanol in the laser transmission path was 1 mm. For the evaluation of conductivity, the resistance value between both ends of the linear conductive pattern was measured with a digital high tester 3256-50 (manufactured by Hioki Electric Co., Ltd.). The smaller the resistance value, the higher the conductivity. The resistance value of the obtained conductive part was 3.7 × 10 3 kΩ.
被覆剤として酢酸を用いた以外は実施例１と同様にして導電部を形成した。得られた導電部の抵抗値は４．７×１０３ｋΩであった。 A conductive portion was formed in the same manner as in Example 1 except that acetic acid was used as a coating agent. The resistance value of the obtained conductive part was 4.7 × 10 3 kΩ.
被覆剤としてアセトンを用いた以外は実施例１と同様にして導電部を形成した。得られた導電部の抵抗値は４．２×１０３ｋΩであった。 A conductive portion was formed in the same manner as in Example 1 except that acetone was used as the coating agent. The resistance value of the obtained conductive part was 4.2 × 10 3 kΩ.
被覆剤として水を用いた以外は実施例１と同様にして導電部を形成した。得られた導電部の抵抗値は７．４×１０３ｋΩであった。
[比較例１]
A conductive portion was formed in the same manner as in Example 1 except that water was used as the coating agent. The resistance value of the obtained conductive part was 7.4 × 10 3 kΩ.
[Comparative Example 1]
被覆剤は用いず、大気中でレーザー照射を行った以外は実施例１と同様にして導電部を形成した。得られた導電部の抵抗値は１．２×１０５ｋΩであった。
[比較例２]
A conductive part was formed in the same manner as in Example 1 except that no coating agent was used and laser irradiation was performed in the atmosphere. The resistance value of the obtained conductive part was 1.2 × 10 5 kΩ.
[Comparative Example 2]
被覆剤は用いず、非酸化性雰囲気下（ＣＯ２雰囲気下）でレーザー照射を行った以外は実施例１と同様にして導電部を形成した。得られた導電部の抵抗値は２．３×１０５ｋΩであった。 A conductive part was formed in the same manner as in Example 1 except that no coating agent was used and laser irradiation was performed in a non-oxidizing atmosphere (CO 2 atmosphere). The resistance value of the obtained conductive part was 2.3 × 10 5 kΩ.
１ セラミックス基材
２ 被覆剤
３ レーザー装置
４ レーザー
DESCRIPTION OF SYMBOLS 1 Ceramic base material 2 Coating agent 3 Laser apparatus 4 Laser
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