JP2004055845A - Circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve coverage at step portions with protection layers. <P>SOLUTION: This circuit board comprises a heat generating resistor layer 13 formed on a substrate 11, a pair of electrode wiring 14a, 14b formed on the substrate 11 so as to penetrate into the heat generating resistor layer 13, a first protection layer 17 formed all over the substrate 11 to cover the electrode wiring 14a, 14b and the heat generating resistor layer 13, and a second protection layer 16 formed on the surface of the first protection layer 17 to cover the heat generating resistor layer 13 and connecting parts between the resistor layer 13 and the electrode wiring 14a, 14b. The thickness of the electrode wiring 14a, 14b is set to be 1500-3000 Å, and the thickness of the first protection layer 17 is set to be 1.0-2.0 times the thickness of the electrode wiring 14a, 14b. The cross section of the electrode wiring 14a, 14b is set to be a taper shape having a taper angle θ of 30-70°. <P>COPYRIGHT: (C)2004,JPO

Description

【００４１】
表１に示すように、電極配線１４ａ，１４ｂのテーパ角度θを７０°以下とした場合には、上記のように非常に厳しい条件の評価においても、発熱抵抗体層１３が浸蝕されず不良の発生がないことがわかる。このことから、テーパ角度θを７０°以下にした場合は、段差部１５，２３での第１保護層１７／第２保護層１６のカバーレージ性が飛躍的に向上していると考えられる。
【００４２】
これに対して、電極配線１４ａ，１４ｂのテーパ角度θを７０°よりも大きくした場合には、発熱抵抗体層１３が浸蝕されて不良が発生していることがわかる。このことから、テーパ角度θを７０°よりも大きくした場合は、段差部１５，２３で第１保護層１７／第２保護層１６の膜厚が薄くなる等の膜厚の不均一が生じ、この膜厚の不均一によりカバーレージ性が悪化していると考えられる。
【００４３】
以上のことから、インクジェットヘッドの使用条件が今後さらに厳しくなったとしても、電極配線１４ａ，１４ｂのテーパ角度θを７０°以下とすれば、段差部１５，２３での第１保護層１７／第２保護層１６のカバーレージ性が飛躍的に向上するため、発熱抵抗体層１３にインクが浸蝕することを回避できると考えられる。また、電極配線１４ａ，１４ｂを再現性良く作製するためには、上述のようにテーパ角度θを３０°以上とする必要がある。以上のことから、電極配線１４ａ，１４ｂのテーパ角度θは３０°〜７０°が好ましい範囲である。
【００４４】
ここで、図４の記録素子基板Ｈ１１００の主要部の平面形状を図８に示し、図８のＸＶＩＩＩ−ＸＶＩＩＩ矢視断面構造を図９に示す。
【００４５】
これらの図において、２５は吐出口１９が形成された吐出口形成部材、２７は上述のように作製された回路基板、２６は回路基板２７と吐出口形成部材２５との密着性を向上させるための密着層である。なお、上述の記録素子基板Ｈ１１００は、回路基板２７に密着層２６および吐出口形成部材２５を形成して作製したものに対応する。以下、その作製方法について説明する。
【００４６】
まず、上述の手順で回路基板２７を形成後、密着層２６として、ポリエーテルアミド樹脂を厚み２．０μｍで形成し、続いて、ＯＤＵＲ（商品名：東京応化工業社製）などの溶解可能な感光性材料であるポジレジストを塗布し、インク流路パターン（不図示）をパターニングする（厚み１２μｍ程度）。
【００４７】
さらに、回路基板２７上に、吐出口形成部材２５として被覆樹脂層を形成し、パターニングによって吐出口１９を形成する。被覆樹脂層としては、吐出口１９をフォトリソグラフィーで容易にかつ精度よく形成できることから、感光性のものが好ましい。また、下部の回路基板２７との密着性、耐インク性を有することが要求されるため、ここではエポキシ樹脂のカチオン重合硬化物を構造材料とするものを用いた。
【００４８】
その後、ＣＤＥ（ケミカルドライエッチング）でインク供給口２１上のＰ−ＳｉＮ膜を除去し、溶解液に浸すことによりＯＤＵＲを除去することにより、インク供給口２１上のＰ−ＳｉＮ膜およびＯＤＵＲからなるインク流路パターンを除去し、さらにエポキシ樹脂を完全に硬化させて吐出口形成部材２５を形成する。この吐出口形成部材２５は、図８、図９に示したように第２保護層１６の一部および第２保護層１６によって覆われていない第１保護層１７の部分に密着層２６を介して接合されている。このように密着層２６を介することにより、第１保護層１７および第２保護層１６を形成した回路基板２７と吐出口形成部材２５との密着性を向上させることができる。また、上述のように、回路基板２７には、第２保護層１６によって覆われた第１保護層１７の部分と第２保護層１６によって覆われていない第１保護層１７の部分との境界部近傍に側壁２８として段差を形成しているため、第２保護層１６の近傍における第１保護層１７と密着層２６との密着性が向上し、吐出口形成部材２５の剥れが生じにくくなる。
【００４９】
次に、上述した回路基板を利用した記録ヘッドカートリッジを組立てた状態の斜視図を図１に、図１の記録ヘッドカートリッジの分解斜視図を図２に、図２のインクジェットヘッドを斜め下方から観た分解斜視図を図３にそれぞれ示す。
【００５０】
図１に示すように、本実施形態に係るインクジェットヘッドＨ１００１は、記録ヘッドカートリッジＨ１０００を構成する一構成要素となっている。この記録ヘッドカートリッジＨ１０００は、インクを貯留するインクタンクＨ１９００と、このインクタンクＨ１９００から供給されるインクを吐出口から吐出させるインクジェットヘッドＨ１００１とから構成されており、不図示のインクジェット記録装置本体のキャリッジに対して着脱可能に搭載される、いわゆるカートリッジ方式を採るものとなっている。この記録ヘッドカートリッジＨ１０００は、キャリッジに搭載された状態で記録媒体の搬送方向と交差する方向に走査されながら、インクジェットヘッドＨ１００１の吐出口からインクを吐出することで記録媒体に対する記録を行う。
【００５１】
ここに示す記録ヘッドカートリッジＨ１０００には、写真調の高画質なカラー記録を可能とするため、インクタンクＨ１９００として、例えばブラック、ライトシアン、ライトマゼンタ、シアン、マゼンタ、およびイエローの各色独立のインクタンクが用意されており、図２に示すように、それぞれがインクジェットヘッドＨ１００１に対して着脱自在となっている。
【００５２】
そして、インクジェットヘッドＨ１００１は、図３の分解斜視図に示すように、本発明の回路基板を利用した上述の記録素子基板Ｈ１１００と、第１のプレートＨ１２００と、電気配線基板Ｈ１３００と、第２のプレートＨ１４００と、タンクホルダＨ１５００と、流路形成部材Ｈ１６００と、フィルタＨ１７００と、シールゴムＨ１８００とから構成されている。
【００５３】
記録素子基板Ｈ１１００には、Ｓｉ基板の片面にインクを吐出するための複数の記録素子（電気熱変換素子）と各記録素子に電力を供給するＡｌ等の電極配線とで構成される熱エネルギー変換手段が成膜技術により形成され、この記録素子に対応した複数のインク流路と複数の吐出口Ｈ１１００Ｔとがフォトリソグラフィ技術により形成されると共に、複数のインク流路にインクを供給するためのインク供給口が裏面に開口するように形成されている。また、記録素子基板Ｈ１１００は第１のプレートＨ１２００に接着固定されており、この第１のプレートＨ１２００には、記録素子基板Ｈ１１００にインクを供給するためのインク連通口Ｈ１２０１が形成されている。さらに、第１のプレートＨ１２００には、開口部を有する第２のプレートＨ１４００が接着固定されており、この第２のプレートＨ１４００は、電気配線基板Ｈ１３００と記録素子基板Ｈ１１００とが電気的に接続されるよう、電気配線基板Ｈ１３００を保持している。この電気配線基板Ｈ１３００は、記録素子基板Ｈ１１００にインクを吐出するための電気信号を印加するものであり、記録素子基板Ｈ１１００に対応する電気配線と、この電気配線端部に位置し記録装置本体からの電気信号を受け取るための外部信号入力端子Ｈ１３０１とを有しており、外部信号入力端子Ｈ１３０１は、タンクホルダＨ１５００の背面側に位置決め固定されている。
【００５４】
一方、インクタンクＨ１９００を着脱可能に保持するタンクホルダＨ１５００には、流路形成部材Ｈ１６００が超音波溶着され、インクタンクＨ１９００から第１のプレートＨ１２００に亙るインク流路Ｈ１５０１を形成している。また、インクタンクＨ１９００と係合するインク流路Ｈ１５０１のインクタンク側端部には、フィルタＨ１７００が設けられ、外部からの塵埃の侵入を防止し得るようになっている。また、インクタンクＨ１９００との係合部にはシールゴムＨ１８００が装着され、係合部からのインクの蒸発を防止し得るようになっている。
【００５５】
さらに、前述のようにタンクホルダＨ１５００、流路形成部材Ｈ１６００、フィルタＨ１７００、およびシールゴムＨ１８００から構成されるタンクホルダ部と、記録素子基板Ｈ１１００、第１のプレートＨ１２００、電気配線基板Ｈ１３００、および第２のプレートＨ１４００から構成される記録素子部とを接着等で結合することにより、インクジェットヘッドＨ１００１を構成している。
【００５６】
なお、本実施形態では、吐出口１９と電気熱変換素子１８とが対向するサイドシュータータイプのインクジェットヘッドＨ１００１について説明したが、吐出口の開口方向が電気熱変換素子の表面に対してほぼ直交するエッジシュータータイプのインクジェットヘッドに対しても本発明を応用することが可能である。
【００５７】
【発明の効果】
以上説明したように本発明によれば、電極配線の厚みを１５００〜３０００Åと薄くするだけでなく、電極配線の断面形状をテーパ角度３０〜７０°のテーパ形状とすることにより、電極配線と発熱抵抗体層とによる段差部での保護層のカバーレージ性をさらに向上させることができる。したがって、本発明をインクジェットヘッドなどの液体吐出ヘッドに適用すれば、発熱抵抗体層がインクなどの液体に浸蝕されるのを防止でき、特に効果的である。
【００５８】
また、第１保護層の厚みを一対の電極配線の１．０〜２．０倍に薄くすることにより、発熱抵抗体層の熱効率を向上することができる。したがって、本発明をインクジェットヘッドなどの液体吐出ヘッドに適用すれば、液体の急速加熱が可能となって発泡安定性を向上させることができる。その結果、液体吐出ヘッドの省電力化および昇温の抑制が可能となり、基板の蓄熱が抑制されて熱応答性が向上し、駆動周波数を高めて高品位のプリント作業を実現することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に用いる記録ヘッドカートリッジを組立てた状態の斜視図である。
【図２】図１に示した記録ヘッドカートリッジの分解斜視図である。
【図３】図２に示したインクジェットヘッドを斜め下方から観た分解斜視図である。
【図４】図３に示した記録素子基板の概略構造を表す破断斜視図である。
【図５】図４に示した記録素子基板のうち本発明の回路基板の主要部を示す平面図である。
【図６】図５中のＸＩＩＩ−ＸＩＩＩ矢視断面図である。
【図７】図５中のＸＩＶ−ＸＩＶ矢視断面図である。
【図８】図４に示した記録素子基板の主要部を示す平面図である。
【図９】図８中のＸＶＩＩＩ−ＸＶＩＩＩ矢視断面図である。
【符号の説明】
１１　　基板
１２　　酸化層
１３　　発熱抵抗体層
１４ａ，１４ｂ　　電極配線
１５　　段差部
１６　　第１保護層
１７　　第２保護層
１８　　電気熱変換素子
１９　　吐出口（Ｈ１１００Ｔ）
２０　　インク室
２１　　インク供給口
２２　　凹部
２３　　段差部
２５　　吐出口形成部材
２６　　密着層
２７　　回路基板
２８　　側壁
Ｈ１０００　　記録ヘッドカートリッジ
Ｈ１００１　　インクジェットヘッド
Ｈ１１００　　記録素子基板
Ｈ１１００Ｔ　　吐出口
Ｈ１２００　　第１のプレート
Ｈ１２０１　　インク連通口
Ｈ１３００　　電気配線基板
Ｈ１３０１　　外部信号入力端子
Ｈ１４００　　第２のプレート
Ｈ１５００　　タンクホルダ
Ｈ１５０１　　インク流路
Ｈ１６００　　流路形成部材
Ｈ１７００　　フィルタ
Ｈ１８００　　シールゴム
Ｈ１９００　　インクタンク[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit board provided with a plurality of heating resistors and a method of manufacturing the same, and more particularly, to a liquid discharge head such as an ink jet head that converts electric energy into heat energy and discharges a liquid using the heat energy. The present invention relates to a circuit board for a liquid ejection head and a method of manufacturing the same.
[0002]
[Prior art]
The ink jet head includes a circuit board provided with a thermal energy generating unit for forming a flying ink droplet by discharging ink from a discharge port. This thermal energy generating means is composed of a heating resistor (electrothermal conversion element) layer that generates heat when energized, and a pair of electrode wires for supplying electricity to the heating resistor layer.
[0003]
When the heating resistor layer is in direct contact with the ink, the heat energy generating means may cause electricity to flow through the ink depending on the electric resistance value of the ink, or may cause the ink itself to be electrolyzed by the flow of electricity through the ink. In addition, when the heating resistor layer is energized, the heating resistor layer and the ink react with each other, which may cause a change in resistance value due to corrosion of the heating resistor layer, or damage or destruction of the heating resistor layer. Was.
[0004]
Therefore, conventionally, alloys such as Ni and Cr, ZrB ₂ , HfB ₂ The heating resistor layer is made of an inorganic material having relatively excellent properties as a heating resistor material such as a metal boride such as metal boride, and SiO 2 is formed on the heating resistor layer made of these materials. ₂ A first protective layer made of a material having excellent oxidation resistance, such as SiN or SiN, prevents the heating resistor layer from directly contacting the ink, solves the above-described problem, and improves reliability and repetition. It has been proposed to improve the durability of use.
[0005]
By the way, when such a thermal energy generating means is formed, it is general that a heating resistor layer is formed on a predetermined substrate, and then an electrode wiring and a first protective layer are sequentially laminated. Such a first protective layer is provided with various functions such as a layer for protecting the heating resistor layer from being damaged or a short circuit between electrode wirings as described above. It is required to uniformly cover a required portion of the wiring without having a defect such as a pinhole.
[0006]
Further, a relatively thin second protective layer is generally provided on the first protective layer so that the first protective layer and the ink are completely shut off. The second protective layer is generally formed by sputtering a thin film of a metal such as Ta. By providing this second protective layer, SiO 2 ₂ , SiN, etc., plays a role in preventing the invasion of ink even if cracks or the like occur due to repeated heat generation by the heating resistor. Further, the second protective layer also plays a role of cavitation protection by repeating foaming and defoaming, and the second protective layer has been intended to improve the durability of repeated use.
[0007]
[Problems to be solved by the invention]
However, in such an ink jet head, as described above, since the electrode wiring is generally formed on the heating resistor layer, a step is generated between the electrode wiring and the heating resistor layer. Since such a step portion is likely to have a non-uniform film thickness, the step portion is provided with a first protective layer / a second protective layer so as not to produce an exposed portion of the heating resistor layer. Have to be fully covered. In a state where the coverage of the stepped portion by the first protective layer / second protective layer is insufficient, the exposed portion of the heating resistor layer comes into direct contact with the ink, and the ink is electrolyzed, In some cases, a chemical reaction occurs between the material and the material forming the heating resistor layer, and the heating resistor layer is eroded and destroyed. In addition, when the film thickness becomes uneven in such a stepped portion, thermal stress generated in the first protective layer / second protective layer due to repetition of heat generation is caused to cause partial concentration of the first protective layer / second protective layer. In some cases, the ink may penetrate into the cracks, causing the above-described heating resistor layer to break.
[0008]
Conventionally, in order to solve such a problem, it is generally practiced to increase the thickness of the first protective layer to about 6000 to 8000 ° so as to improve the coverage of the step portion and reduce the number of pinholes. However, if the first protective layer is made thicker, the thermal resistance of the first protective layer increases and the thermal efficiency decreases, so that more heat than necessary must be generated in the heating resistor layer, and the heat is stored in the substrate. As a result, thermal responsiveness deteriorates, and another problem arises that the durability of the heat generating resistor layer deteriorates due to excessive power.
[0009]
Such a problem can be overcome by reducing the thickness of the first protective layer to about 3000 ° to improve the thermal efficiency of the first protective layer. However, when the first protective layer is thinned, as described above, the cover rage of the step portion is reduced. A problem such as erosion of the heat-generating resistor layer due to deterioration of the properties arises.
[0010]
Therefore, conventionally, when the first protective layer is formed to be thin, the thickness of the electrode wiring, which was about 4000 to 8000 °, is reduced to about 2000 ° to reduce the step, thereby improving the poor coverage of the step. Accordingly, both improvement of the thermal efficiency and improvement of the coverage of the step portion have been achieved.
[0011]
On the other hand, in recent inkjet heads, the use conditions have been higher than in the past, such as the demand for further improvement in durability and the demand for further improvement in the corrosion resistance of ink resistance due to the diversification of ink types. Also tend to be more severe.
[0012]
Therefore, in order to prevent the heating resistor layer from being eroded even under the conditions of use of such an ink jet head, it is important to form the first protective layer / second protective layer on the step portion with good coverage. However, there is a possibility that this cannot be achieved only by reducing the thickness of the electrode wiring, and it is required to further improve the coverage of the step portion by the first protective layer / second protective layer.
[0013]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit board and a method of manufacturing the circuit board, which can further improve the coverage by a protective layer in a stepped portion formed by an electrode wiring and a heating resistor layer.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a circuit board according to the present invention includes an electrothermal conversion element formed on a surface portion of the substrate for generating thermal energy, and a surface portion of the substrate so as to be electrically connected to the electrothermal conversion element. And a first protective layer formed over substantially the entire surface of the substrate to cover the electrode wiring and the electrothermal transducer, wherein the thickness of the electrode wiring is 1500. And the thickness of the first protective layer is 1.0 to 2.0 times the thickness of the pair of electrode wires, and the cross-sectional shape of the pair of electrode wires is 30 to 70. It has a tapered shape in the range of °.
[0015]
According to this configuration, not only the thickness of the electrode wiring is reduced to 1500 to 3000 °, but also the cross-sectional shape of the electrode wiring is tapered at a taper angle of 30 to 70 °. It is possible to further improve the coverage of the protective layer in the portion.
[0016]
Further, the tapered shape of the pair of electrode wires may be formed by dry etching.
[0017]
In order to achieve the above object, a method of manufacturing a circuit board according to the present invention includes the steps of forming an electrothermal conversion element for generating thermal energy on the surface of the board; Forming an electrode wiring having a thickness of 3000 ° on the surface of the substrate, and processing the electrode wiring into a tapered shape having a taper angle of 30 to 70 °; and forming the electrode wiring and the electrothermal transducer. Forming a first protective layer having a thickness of 1.0 to 2.0 times as large as the electrode wiring over substantially the entire surface of the substrate.
[0018]
Further, the tapered shape of the pair of electrode wirings may be formed by dry etching.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
The circuit board and the method of manufacturing the same according to the present invention can be applied to any circuit board provided with a plurality of heating resistors, and among them, the circuit board is provided in a liquid ejection head such as an inkjet head. It is particularly suitably applied to a circuit board. Therefore, hereinafter, a circuit board provided in an ink jet head and a method for manufacturing the same will be described as an example of a circuit board and a method for manufacturing the same according to the present invention.
[0020]
FIG. 4 is a cross-sectional view of a part of a printing element substrate H1100 to which the circuit board of the present invention is applied, and FIG. 5 particularly shows a plan shape of a main part of the circuit board of the present invention. 6 and 7 show a cross-sectional structure and a cross-sectional structure taken along the line XIV-XIV, respectively.
[0021]
In these figures, reference numeral 11 denotes a substrate provided with an electrothermal conversion element (recording element) 18, and the electrothermal conversion element 18 is formed by the heating resistor layer 13 located between the pair of electrode wirings 14a and 14b. Is done. Reference numerals 15 and 23 denote steps formed from the pair of electrode wires 14a and 14b and rising from the heating resistor layer 13, reference numeral 17 denotes a first protective layer, and reference numeral 16 denotes a second protective layer. Reference numeral 19 denotes a discharge port for discharging ink droplets, reference numeral 20 denotes an ink chamber for supplying ink to the discharge port 19, and reference numeral 21 denotes an ink supply port which opens to the substrate 11 for supplying ink to the ink chamber 20. is there.
[0022]
The substrate 11 is formed by patterning a heating resistor layer 13 and a pair of electrode wirings 14a and 14b on a Si wafer by a photolithography technique, forming an ink chamber 20 and a discharge port 19 with a photosensitive resin, and performing anisotropic etching. Is formed by cutting the Si wafer after the ink supply port 21 is formed. Then, an electric wiring board H1300 (see FIG. 3) for transferring electric signals for driving the electrothermal transducer 18 is connected to the substrate 11 by a mounting technique. That is, on the electric wiring substrate H1300, a power transistor for switching the current to the electrothermal transducer 18 and a CMOS logic circuit for controlling the power transistor are formed using semiconductor technology as driving means. It is connected to the electrothermal transducer 18 via 14a and 14b.
[0023]
In the present embodiment, the two rows of discharge ports 19 parallel to each other with the ink supply port 21 interposed therebetween are arranged in a so-called zigzag manner by being shifted by half a pitch from each other, and ink chambers 20 corresponding to the discharge ports 19 of each row are arranged. Are arranged at a pitch of 600 dpi.
[0024]
An electrothermal conversion element (recording element) 18 is provided in each ink chamber 20 so that a predetermined amount of ink droplet can be ejected from each ejection port 19.
[0025]
In this embodiment, first, a Si wafer is used as the substrate 11, and this Si wafer is thermally oxidized to a SiO.sub. ₂ An oxide layer 12, which is a film, is formed.
[0026]
Next, a heating resistor layer 13 is formed on the oxide layer 12 by sputtering to a thickness of about 500 °. Although TaN is used as the heating resistor layer 13 in this embodiment, HfB ₂ Or TaSiN may be used.
[0027]
Then, after forming an Al layer as the electrode wirings 14a and 14b to a thickness of about 2000 ° with a tolerance of ± 300 °, a wiring region is patterned using a mask. In the present embodiment, Al is used for the electrode wires 14a and 14b, but an alloy such as Al-Si, Al-Cu, or Al-Si-Cu may be used.
[0028]
Increasing the film thickness of the electrode wirings 14a and 14b causes unevenness in the film thickness of the first protective layer 17 / second protective layer 16, particularly at the step portions 15 and 23, and leads to deterioration of the coverage property. It becomes. On the other hand, reducing the film thickness of the electrode wirings 14a and 14b increases the wiring resistance, and the power consumption increases due to the wiring resistance, and the temperature of the substrate 11 increases. Therefore, the thickness of the electrode wirings 14a and 14b is preferably in the range of 1500 to 3000 ° in view of the above points. 6 is dry-etched at the time of forming the first protective layer 17 / second protective layer 16 in order to improve the adhesion with the discharge port forming member 25 (see FIGS. 8 and 9) described later. The discharge port forming member 25 is formed on the side wall 28, so that there is no problem with the coverage of the step on the side wall 28.
[0029]
Next, in order to form a portion of the electrothermal conversion element 18, patterning is performed using a mask, and thereafter, the Al layer of the portion of the electrothermal conversion element 18 is removed by wet etching. Then, the portion where the Al layer remains is subjected to dry etching simultaneously with the heating resistor layer 13 to form the electrode wirings 14a and 14b having a tapered cross section. The taper angle θ of the electrode wirings 14a and 14b is preferably in the range of 30 ° to 70 °, but the basis of this numerical value will be described later.
[0030]
Next, a first protective layer 17 of P-SiN is formed by a CVD method. The film thickness of the first protective layer 17 is about 3000 ° and the film is formed with a tolerance of ± 400 °. However, it is also possible to form silicon oxide as the first protective layer 17.
[0031]
Increasing the thickness of the first protective layer 17 causes deterioration of the durability of the heating resistor layer 13 due to a decrease in thermal efficiency. On the other hand, if the thickness of the first protective layer 17 is reduced, the thickness of the electrode wirings 14a and 14b may be uneven, particularly at the step portions 15 and 23, depending on the thickness of the electrode wires 14a and 14b. Will be invited. Therefore, the thickness of the first protective layer 17 is preferably in the range of 1.0 to 2.0 times the electrode wirings 14a and 14b in view of the above points.
[0032]
Next, Ta was formed as the second protective layer 16 by sputtering. The film thickness was set to 2300 ° and the film was formed within a tolerance range of ± 280 °. TaN, TaSiN, or the like may be used as the second protective layer 16 instead of Ta.
[0033]
Next, in order to remove an unnecessary portion of Ta which is the second protective layer 16, patterning is performed again, and then removed by a dry etching method. The dry etching time is set in the concave portion 22 between the heating resistor layers 13 (and the electrode wirings 14a and 14b alternately arranged on the heating resistor layers 13) arranged in parallel along the arrangement direction of the electrothermal transducers 18. The over-etched state is set so that the layer 16 does not remain. If there is a pinhole in the first protection layer 17 below the remaining portion where the second protection layer 16 remains, the remaining portion and the wiring electrodes 14a and 14b are energized and the remaining portion is oxidized. Here, when the remaining portion is energized with the second protective layer 16 left as necessary, the necessary portion of the second protective layer 16 is oxidized, and cavitation protection may not be possible. Therefore, in order to remove unnecessary portions of the second protective layer 16 without remaining, it is preferable that the over-etching amount is 100 ° or more.
[0034]
In this dry etching, the jetting direction of the etching gas is set, for example, perpendicular to the surface of the substrate 11, thereby forming the heating resistor layer 13 and the electrode wirings 14 a and 14 b to form the surface of the substrate 11 (in the illustrated example, The first protective layer 17 at the steps 15, 23 rising from the surface of the oxide layer 12) is inclined with respect to the direction of jetting the etching gas. As a result, there is no problem that the electrode wirings 14a and 14b overlapping the heating resistor layer 13 are damaged. However, if the first protective layer 17 is excessively etched away by the over-etching, the electrode portions 14a and 14b may be damaged because the steps 15 and 23 having a rough film quality are quickly etched.
[0035]
By performing such anisotropic dry etching, even if the first protection layer 17 of the steps 15 and 23 rising from the surface of the substrate 11 has a crack, the electrode wiring 14 a overlapping the heating resistor layer 13 is formed. , 14b are less likely to be damaged.
[0036]
Further, when the over-etching state is performed by such dry etching, a portion of the first protection layer 17 covered by the second protection layer 16 and a portion of the first protection layer 17 not covered by the second protection layer 16 are formed. A step may be formed as a side wall 28 in the vicinity of the boundary between the openings to improve the adhesion to the discharge port forming member 25 described later.
[0037]
Hereinafter, the grounds for setting the taper angle θ of the electrode wires 14a and 14b in the range of 30 to 70 ° will be described. Here, the following evaluation was performed in order to obtain the optimum range of the taper angle θ of the electrode wires 14a and 14b.
[0038]
First, 6,400 circuit boards each having the taper angles θ of the electrode wires 14a and 14b of 30 °, 50 °, 70 °, 75 °, 80 °, and 85 ° were manufactured by the above-described procedure. If the taper angle θ was less than 30 °, the dimensional accuracy was unstable, and it was not possible to manufacture with good reproducibility. At this time, the thickness of the electrode wirings 14a and 14b is 2000 °, and the thickness of the first protective layer 17 is 3000 ° (1.5 times the electrode wirings 14a and 14b).
[0039]
Then, the circuit board manufactured as described above is immersed in a solution of BHF (buffered hydrofluoric acid), which is a main component of the ink, and the first protective layer 17 / second protective layer 16 deteriorates the coverage therefrom. The erosion of the heating resistor layer 13 was regarded as defective, and the number thereof was evaluated. Table 1 shows the evaluation results.
[0040]
[Table 1]

[0041]
As shown in Table 1, when the taper angle θ of the electrode wirings 14a and 14b is set to 70 ° or less, the heating resistor layer 13 is not eroded even in the evaluation of the very severe conditions as described above, and the defect is not good. It can be seen that there is no occurrence. From this, it is considered that when the taper angle θ is set to 70 ° or less, the coverage of the first protective layer 17 / second protective layer 16 at the steps 15 and 23 is dramatically improved.
[0042]
On the other hand, when the taper angle θ of the electrode wires 14a and 14b is set to be larger than 70 °, the heating resistor layer 13 is eroded and a defect occurs. For this reason, when the taper angle θ is larger than 70 °, the thickness of the first protective layer 17 / the second protective layer 16 becomes uneven at the steps 15, 23, and the film thickness becomes non-uniform. It is considered that the unevenness of the film thickness deteriorates the coverage property.
[0043]
From the above, even if the use conditions of the inkjet head become more severe in the future, if the taper angle θ of the electrode wirings 14a and 14b is set to 70 ° or less, the first protective layer 17 / the It is considered that since the coverage of the second protective layer 16 is dramatically improved, it is possible to prevent the ink from eroding the heating resistor layer 13. Further, in order to manufacture the electrode wirings 14a and 14b with good reproducibility, the taper angle θ needs to be 30 ° or more as described above. From the above, the taper angle θ of the electrode wires 14a and 14b is preferably in the range of 30 ° to 70 °.
[0044]
Here, FIG. 8 shows a plan shape of a main part of the printing element substrate H1100 in FIG. 4, and FIG. 9 shows a cross-sectional structure taken along the line XVIII-XVIII in FIG.
[0045]
In these figures, reference numeral 25 denotes a discharge port forming member in which the discharge ports 19 are formed, 27 denotes a circuit board manufactured as described above, and 26 denotes a circuit board 27 for improving the adhesion between the circuit board 27 and the discharge port forming member 25. Is an adhesion layer. Note that the above-described recording element substrate H1100 corresponds to one manufactured by forming the adhesion layer 26 and the discharge port forming member 25 on the circuit board 27. Hereinafter, the manufacturing method will be described.
[0046]
First, after the circuit board 27 is formed by the above-described procedure, a polyetheramide resin is formed to a thickness of 2.0 μm as the adhesion layer 26, and then a dissolvable material such as ODUR (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) A positive resist, which is a photosensitive material, is applied, and an ink flow path pattern (not shown) is patterned (thickness: about 12 μm).
[0047]
Further, a coating resin layer is formed as the discharge port forming member 25 on the circuit board 27, and the discharge ports 19 are formed by patterning. The coating resin layer is preferably photosensitive because the discharge port 19 can be easily and accurately formed by photolithography. Further, since it is required to have adhesiveness to the lower circuit board 27 and ink resistance, here, a structure material made of a cationically polymerized and cured epoxy resin is used.
[0048]
Thereafter, the P-SiN film on the ink supply port 21 is removed by CDE (chemical dry etching), and the ODUR is removed by immersing the P-SiN film in the solution and the P-SiN film and the ODUR on the ink supply port 21 are formed. The ink flow path pattern is removed, and the epoxy resin is completely cured to form the discharge port forming member 25. As shown in FIGS. 8 and 9, the discharge port forming member 25 has an adhesive layer 26 interposed between a part of the second protective layer 16 and a part of the first protective layer 17 not covered by the second protective layer 16. Are joined. By interposing the adhesion layer 26 in this manner, the adhesion between the circuit board 27 on which the first protection layer 17 and the second protection layer 16 are formed and the ejection port forming member 25 can be improved. As described above, the circuit board 27 has a boundary between the portion of the first protective layer 17 covered by the second protective layer 16 and the portion of the first protective layer 17 not covered by the second protective layer 16. Since the step is formed as the side wall 28 in the vicinity of the portion, the adhesion between the first protective layer 17 and the adhesive layer 26 in the vicinity of the second protective layer 16 is improved, and the discharge port forming member 25 is less likely to peel off. Become.
[0049]
Next, FIG. 1 is a perspective view showing a state where the recording head cartridge using the above-described circuit board is assembled, FIG. 2 is an exploded perspective view of the recording head cartridge of FIG. 1, and FIG. The exploded perspective views are shown in FIG.
[0050]
As shown in FIG. 1, the ink jet head H1001 according to the present embodiment is one component of a print head cartridge H1000. The recording head cartridge H1000 includes an ink tank H1900 for storing ink and an ink jet head H1001 for discharging ink supplied from the ink tank H1900 from a discharge port. A so-called cartridge system which is removably mounted on the printer is adopted. The recording head cartridge H1000 performs recording on the recording medium by ejecting ink from the ejection openings of the inkjet head H1001 while scanning in a direction intersecting the transport direction of the recording medium while being mounted on the carriage.
[0051]
The recording head cartridge H1000 shown here includes, for example, black, light cyan, light magenta, cyan, magenta, and yellow independent ink tanks as the ink tank H1900 in order to enable high-quality photographic color recording. As shown in FIG. 2, each is detachable from the inkjet head H1001.
[0052]
Then, as shown in the exploded perspective view of FIG. 3, the inkjet head H1001 includes the above-described recording element substrate H1100 using the circuit board of the present invention, a first plate H1200, an electric wiring substrate H1300, and a second It comprises a plate H1400, a tank holder H1500, a flow path forming member H1600, a filter H1700, and a seal rubber H1800.
[0053]
The printing element substrate H1100 includes a plurality of printing elements (electrothermal conversion elements) for ejecting ink to one side of a Si substrate and electrode wirings such as Al for supplying power to each printing element. The means is formed by a film forming technique, a plurality of ink flow paths and a plurality of ejection ports H1100T corresponding to the recording elements are formed by a photolithography technique, and ink for supplying ink to the plurality of ink flow paths is provided. The supply port is formed to open on the back surface. The printing element substrate H1100 is bonded and fixed to a first plate H1200. The first plate H1200 has an ink communication port H1201 for supplying ink to the printing element substrate H1100. Further, a second plate H1400 having an opening is adhered and fixed to the first plate H1200, and the second plate H1400 is electrically connected to the electric wiring substrate H1300 and the recording element substrate H1100. So that the electric wiring board H1300 is held. The electric wiring board H1300 is for applying an electric signal for discharging ink to the recording element substrate H1100. The electric wiring corresponding to the recording element substrate H1100 and an electric wiring located at the end of the electric wiring and from the main body of the printing apparatus. And an external signal input terminal H1301 for receiving the electric signal of the above. The external signal input terminal H1301 is positioned and fixed to the rear side of the tank holder H1500.
[0054]
On the other hand, a flow path forming member H1600 is ultrasonically welded to a tank holder H1500 that detachably holds the ink tank H1900 to form an ink flow path H1501 extending from the ink tank H1900 to the first plate H1200. In addition, a filter H1700 is provided at the end of the ink flow path H1501 on the ink tank side that engages with the ink tank H1900, so that intrusion of dust from the outside can be prevented. In addition, a seal rubber H1800 is attached to an engagement portion with the ink tank H1900, so that evaporation of ink from the engagement portion can be prevented.
[0055]
Further, as described above, the tank holder section including the tank holder H1500, the flow path forming member H1600, the filter H1700, and the seal rubber H1800, the recording element substrate H1100, the first plate H1200, the electric wiring board H1300, and the second The inkjet head H1001 is configured by bonding the recording element unit composed of the plate H1400 with an adhesive or the like.
[0056]
In the present embodiment, the side shooter type ink jet head H1001 in which the discharge port 19 and the electrothermal conversion element 18 face each other has been described, but the opening direction of the discharge port is substantially orthogonal to the surface of the electrothermal conversion element. The present invention can be applied to an edge shooter type inkjet head.
[0057]
【The invention's effect】
As described above, according to the present invention, not only the thickness of the electrode wiring is reduced to 1500 to 3000 °, but also the cross-sectional shape of the electrode wiring is tapered at a taper angle of 30 to 70 °. It is possible to further improve the coverage of the protective layer at the step due to the resistor layer. Therefore, when the present invention is applied to a liquid ejection head such as an ink jet head, it is possible to prevent the heating resistor layer from being eroded by a liquid such as ink, which is particularly effective.
[0058]
Further, by reducing the thickness of the first protective layer to 1.0 to 2.0 times the thickness of the pair of electrode wires, the thermal efficiency of the heating resistor layer can be improved. Therefore, if the present invention is applied to a liquid ejection head such as an ink jet head, rapid heating of the liquid becomes possible, and the foaming stability can be improved. As a result, it is possible to save power and suppress a rise in temperature of the liquid ejection head, suppress heat storage of the substrate, improve thermal responsiveness, and increase the driving frequency to realize high-quality printing.
[Brief description of the drawings]
FIG. 1 is a perspective view of an assembled state of a recording head cartridge used in an embodiment of the present invention.
FIG. 2 is an exploded perspective view of the recording head cartridge shown in FIG.
FIG. 3 is an exploded perspective view of the inkjet head shown in FIG. 2 as viewed obliquely from below.
FIG. 4 is a cutaway perspective view showing a schematic structure of the recording element substrate shown in FIG.
FIG. 5 is a plan view showing a main part of the circuit board of the present invention among the printing element substrates shown in FIG. 4;
FIG. 6 is a sectional view taken along the arrow XIII-XIII in FIG. 5;
FIG. 7 is a sectional view taken along the arrow XIV-XIV in FIG. 5;
FIG. 8 is a plan view showing a main part of the recording element substrate shown in FIG.
9 is a sectional view taken along the arrow XVIII-XVIII in FIG.
[Explanation of symbols]
11 Substrate
12 Oxidation layer
13 Heating resistor layer
14a, 14b electrode wiring
15 Step
16 First protective layer
17 Second protective layer
18 Electrothermal conversion element
19 Discharge port (H1100T)
20 ink chamber
21 Ink supply port
22 recess
23 Step
25 Discharge port forming member
26 Adhesion layer
27 circuit board
28 Side wall
H1000 print head cartridge
H1001 inkjet head
H1100 printing element substrate
H1100T outlet
H1200 first plate
H1201 Ink communication port
H1300 Electric wiring board
H1301 External signal input terminal
H1400 Second plate
H1500 Tank holder
H1501 Ink flow path
H1600 channel forming member
H1700 filter
H1800 Seal rubber
H1900 ink tank

Claims (4)

An electrothermal conversion element formed on the surface of the substrate to generate thermal energy, an electrode wiring formed on the surface of the substrate so as to conduct to the electrothermal conversion element, A first protective layer formed over substantially the entire area and covering the electrode wiring and the electrothermal transducer.
The thickness of the electrode wiring is in the range of 1500 to 3000 °, the thickness of the first protective layer is in the range of 1.0 to 2.0 times the thickness of the pair of electrode wirings, and the cross section of the pair of electrode wirings is A circuit board having a tapered shape in a taper angle range of 30 to 70 °. The circuit board according to claim 1, wherein the tapered shape of the electrode wiring is formed by dry etching. Forming an electrothermal transducer for generating thermal energy on the surface of the substrate;
Forming electrode wiring having a thickness of 1500 to 3000 ° on the surface of the substrate so as to conduct to the electrothermal transducer, and processing the electrode wiring into a tapered shape having a taper angle of 30 to 70 °; When,
Forming a first protective layer having a thickness of 1.0 to 2.0 times the electrode wiring over substantially the entire surface of the substrate, covering the electrode wiring and the electrothermal transducer;
A method for manufacturing a circuit board, comprising: 4. The method according to claim 3, wherein the tapered shape of the electrode wiring is formed by dry etching.

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