JP4235036B2 - Fluorescent display tube - Google Patents

Description

表１から、Ａｇの含有量が１０ｖｏｌ％以上であれば電気抵抗率が１０Ω／□以下となっている。
【００３３】
Ａｇの比率が１０ｖｏｌ％以上含まれていれば、３５０℃焼成で８０ｇ、４５０℃焼成で１０００ｇ以上の固着強度が得られ、蛍光表示管の途中工程及び完成品の固着強度として十分なものであった。
前述の導電性組成物（Ａ）を使用して作製した蛍光表示管のグリッドを、バネばかりで剥がして固着強度を測定したところ、４５０℃の固着強度は１８０ｇであり、４５０℃で焼成後冷却して形成した中付け電極６はグリッドを剥がすとグリッドに付着して、陽極基板から剥離した。
【００３４】
これに対し、本願発明の導電性組成物を使用した蛍光表示管を作成して、グリッドをバネばかりで剥がす固着強度試験を実施したところ、４５０℃の固着強度が１８０ｇ以上であった。
４５０℃で焼成後冷却して形成した中付け電極６で固着されたグリッドを剥がしたところ、グリッドのみが離脱され、陽極基板に固着され剥離しなかった。
さらに、本願の導電性組成物を使用した場合は中付け電極６の剥離及び基板側のクラックも激減した。
Ａｇ含有量が７０ｖｏｌ％を越すと熱膨張係数が１５７．３×１０^−７／℃以上となりソーダライムガラス上面に当該導電性電極を形成するとクラックが発生してしまうことを示している。
以上から、Ａｇの含有量は１０〜６０ｖｏｌ％、好ましくは１０〜３５ｖｏｌ％が好適である事ことを示している。
【００３５】
次に、低融点ガラスの含有量の組成範囲を確定する為に、顔料の含有量を１０ｖｏｌ％に固定して、Ａｇの含有量を１０〜６０ｖｏｌ％としたときに、熱膨張係数を６０×１０^−７／℃よりも大きくなるように低融点ガラスの組成比率を変化させて、Ａｇ、フィラー、顔料を組み合わせて導電ペーストを作成後、該導電ペーストをガラス基板上面に塗布後４５０℃焼成して、電気抵抗、熱膨張係数、固着強度を測定した結果を表２〜表７に示す。
【００３６】
【表２】
Ａｇの含有率を１０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００３７】
【表３】
Ａｇの含有率を２０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００３８】
【表４】
Ａｇの含有率を３０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００３９】
【表５】
Ａｇの含有率を４０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００４０】
【表６】
Ａｇの含有率を５０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００４１】
【表７】
Ａｇの含有率を６０ｖｏｌ％に固定し、低融点ガラスの含有量を変化させた場合の電気抵抗、熱膨張係数、固着強度を示す表。

【００４２】
前記、表２〜表７から、低融点ガラスの含有率が１０ｖｏｌ％未満では、１００ｇに満たない為十分な固着力が得られず、７０ｖｏｌ％を越すと熱膨張係数が１４８．４×１０^−７／℃をなることから、低融点ガラスの含有量は１０ｖｏｌ％〜７０ｖｏｌ％が好適であること示している。
次に、フィラー、及び、顔料の含有量の最適値を求める為に、Ａｇの含有量を下限値の１０ｖｏｌ％及び上限値の６０ｖｏｌ％とし、低融点ガラスの含有量を下限値の１０ｖｏｌ％及び上限値の３０ｖｏｌ％とし、顔料を１０ｖｏｌ％に固定して導電ペーストを作成後、該導電ペーストをガラス基板上面に塗布後３５０℃及び４５０℃で焼成して、電気抵抗、熱膨張係数、固着強度を測定した結果を表８に示す。
【００４３】
【表８】
顔料とフィラーの含有量の最適値を求める表。

表８から、フィラーは顔料との相乗効果を奏して７０ｖｏｌ％含んでいてもＡｇ，ガラスがそれぞれ１０ｖｏｌ％含まれていれば、導電性組成物としての中付け電極の働きをすることを示している。
【００４４】
【表９】
導電性組成物の銀粉末と低膨張フィラー粉末が重量比を求める表

表９は、ガラス粉末の量を従来よりも少ない２０ｖｏｌ％を一定にして、Ａｇ粉末を１０〜６０ｖｏｌ％の間で変化させ、ジルコン粉末（低融点フィラー）の量を調整することにより焼成後の熱膨張率が６０×１０^−７／℃よりも大きくなる様に作成した導電性組成物を中付け電極とした場合の基板のクラック状態を調査した。
前述の低融点ガラスＢｉ_２Ｏ_３−Ｂ_２Ｏ_３系低融点ガラスと、フィラーとしてジルコンを使用して、熱膨張率が導電性組成物の導電性組成物のＡｇ粉末と低膨張フィラー粉末の組成比が、Ａｇ粉末と低膨張フィラー粉末が重量比で１：７〜１１：５の比率であれば実用上問題がないこと示している。
【００４５】
以上から、Ａｇ：１０〜６０Ｖｏｌ％、低融点ガラス：１０〜８０Ｖｏｌ％、フィラー：０〜７０Ｖｏｌ％、顔料：５〜８０Ｖｏｌ％をビークルに混練した導電性ペースト作成し、該導電性ペーストを３００〜５００℃で焼成した場合、表面抵抗が２Ω/□以下であり、熱膨張率が６２．７×１０^−７／℃〜１３３．３５×１０^−７／℃の導電性組成物が得られた。
【００４６】
前記、Ａｇ粒子、低融点ガラス及びフィラーの粒径は、１〜２０μｍが好ましい。粒径が大きすぎると低融点ガラス及びＡｇ粒子等が溶融したときのコンプレッションが低下して低効率が上昇し、かつ、スクリーン印刷をした場合に通常使用されるスクリーンの開口部６０μｍ□を通過し難くなる。
粒径が小さすぎる場合は、粒子同士が緻密に充填されることになる。従って、各粒子間のバインダーが焼成に際にブリスター（空洞）を形成して接着強度が弱くなるために好ましくない。
【００４７】
前記Ａｇ粒子の形状はフレーク状が好ましい。その理由として、フレーク状の場合には低融点ガラスが溶融した時、Ａｇ粒子は面接触して低抵抗化するものである。
低融点ガラス及びフィラーの形状は、フレーク状のみの配合ではチクソ比が高くなり作業性は悪くなる。又、適度なレベリング性を出すため球状を併用したペーストを使用して印刷性を向上できる。
【００４８】
本願発明の適用例として蛍光表示管用グリッド電極を固着する為の導電性接着剤として使用した中付け電極６を採用した蛍光表示管について図１を参考に説明する。
前記ガラス基板１の上面には配線導体２ａ、２ｂのパターンが配設されている。
配線導体２ｂはグリッド電極９と外囲器の外側に延出しているリード１５と接続させるグリッド配線２ａと、陽極導体３と蛍光体４から構成されるアノード５に接続されるアノード配線２ａがある。
【００４９】
配線２の上には絶縁層８がスクリーン印刷法で被着される。この絶縁層８には、アノード５の位置及びグリッド９とグリッド配線２ｂを接続させる位置にスルーホール７が設けられている。そして、絶縁層８には黒色顔料が混入されており、黒色の背景として作用している。
前記アノード配線２ａの端部のスルーホール７上に黒鉛ペーストを塗布して形成した陽極導体３上に蛍光体層４が被着形成されてアノード５を形成している。
又、グリッド配線２ｂの外囲器内の端部にはスルーホール７上に導電性接着剤として作用する中付け電極６が配設され、そこにグリッド９の足部が埋め込まれて、固着している。
【００５０】
前記中付け電極６は、導電物質としての粒径１〜２０μｍのＡｇ粉末を２０．０〜２４．０ｖｏｌ％(好適には２２.５ｖｏｌ％)、接着成分の一部を構成するフリットガラスとして粒径１〜２０μｍのＢｉ_２Ｏ_３−Ｂ_２Ｏ_３系低融点ガラスを１２．５〜２０．０ｖｏｌ％（好適には１５ｖｏｌ％）、フィラーとしてジルコンを４８．５〜５５．０ｖｏｌ％(好適には５２．５ｖｏｌ％)、顔料として径１〜２０μｍのＣｕ−Ｃｒ系顔料を７．５〜１４．５ｖｏｌ％(好適には１０ｖｏｌ％)からなる導電性組成物を、ターピネオール等の有機溶剤中に印刷性向上のためのエチルセルロース等のバインダーを１〜５％溶解してなるペースト化する為の有機ビークルはそれぞれ従来と同様に６ｖｏｌ％前後を使用して導電性ペーストとして使用される。
【００５１】
次に、該中付け電極６に対し、グリッド９を固着する場合にて説明する。
前記導電性組成物を含む導電性ペーストをスクリーン印刷法で被着し、その後グリッド９を載置した状態で、導電性ペーストの有機成分を分解蒸発させることにより、グリッド９を陽極基板に固着する。
このようにして、表面に蛍光体層を有するアノード５及び該陽極の上方に配設されるグリッド９が配設された陽極基板が完成する。
【００５２】
前述の工程で完成した陽極基板を一部として、前面版１３、側面版１４を低融点ガラスにより真空容器を構成し、内部に前述の陽極５、グリッド９、該グリッド固着用導電性組成物からなる中付け電極６、熱電子を放出するためのカソード、外部からの電気信号を入力するための金属リード１５からなる蛍光表示管を構成し、内部を高真空にした蛍光表示管が完成する。
【００５３】
蛍光表示管の用途拡大により、ガラス基板上面と絶縁層の間にＳｉＯ _２ 等の層１１を設ける場合や、前記導電性組成物（中付けパターン）の上面に結晶性ガラス層１２を設ける場合がある。
この場合は、ソーダライムガラス中のＮａイオンを遮蔽するため等に使用されるＳｉＯ _２ 層１１の形成や、中付け用導電性組成物上に結晶化ガラス１２の塗布を実施する場合に、クラックが発生し易くなっている。
【００５４】
上述の導電性組成物を蛍光表示管の中付け電極６に使用した蛍光表示管に於いては、前記中付け電極６にひび割れは発生せず、陽極基板のクラックも発生していなかった。
更に、前記蛍光表示管の陽極基板上に設けた厚み１．０ｍｍの導電性組成物も剥離せずに、基板側のクラックも発生していなかった。
更に、配線導体２ａ、２ｂの端子部にされた配線導体に本願発明の導電性組成物を該配線導体上面に形成した端子電極１６と、金属リード１５と接続することにより一層接続の信頼性を向上することが出来る。
【００５５】
【効果】
本願発明による効果は以下の通りである。
３００μｍ以上の厚い膜をひび割れ・剥離を発生させずに形成する場合に適応できる導電性焼結体を得られたことによる効果は産業上大きいものである。
更に、蛍光表示管の表示内容の複雑化及び多様化に伴い従来問題となる微細な中付けパターンとの界面の基板クラック及び剥離を防止できたことによる効果は産業上大きいものである。
並びに、環境負荷物質である鉛を含まない低融点ガラスを使用した前記厚い導電性組成物を提供できたことによる効果は産業上大きいものである。
【００５６】
【図面の簡単な説明】
【図１】従来のグリッド中付け方式蛍光表示管の断面図
【図２】Ａｇと、Ｂｉ_２Ｏ_３−Ｂ_２Ｏ_３系低融点ガラスと、ジルコン粒子と、金属酸化物系顔料を各々３００℃及び３５０℃で焼成して固着強度を測定したグラフ
【図３】前記導電性ペーストＡ、Ｂをソーダライムガラス上面に塗布後、１００℃〜５００℃で焼成して固着力を焼成したときの固着強度を示す図。
【図４】前記導電性ペーストＡ、Ｂをソーダライムガラス上面に塗布後、３００℃、３５０℃で焼成して固着力を焼成したときの固着強度を示す図。
【符号の説明】
１ ...ガラス基板
２ａ...アノード配線
２ｂ...グリッド配線
３ ...陽極導体
４ ...蛍光体
５ ...アノード
６ ...中付け電極
７ ...スルーホール
８ ...絶縁層
９ ...グリッド
１０...カソード
１１...ＳｉＯ２層
１２...結晶性ガラス
１３...前面板
１４...側面板
１５...金属リード
１６...端子電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive composition formed on an insulating substrate, and a fluorescent display tube using the conductive composition as an electrode.
[0002]
[Prior art]
When an electrode is formed on an insulating substrate, a conductive paste is prepared by kneading Ag particles as a conductive material and low melting point glass as a fixing component in an organic vehicle, and the conductive paste is applied by a printing method or the like. By firing the formed insulating substrate in a high temperature atmosphere, the conductive composition mainly composed of the Ag particles and the low-melting glass is fixed to the insulating substrate.
The conductive composition formed on the insulating substrate is used as various electrodes.
In particular, since the conductive electrode formed on the upper surface of a glass such as a fluorescent display tube is formed by firing in a relatively low temperature range of 300 to 500 ° C., lead-based glass has been used as a fixing component. .
[0003]
FIG. 1 is a partial cross-sectional view of a conventional grid-attached fluorescent display tube, in which a conductive composition is used for the intermediate electrode 6.
The conventional intermediate electrode 6 is formed by patterning a conductive paste obtained by kneading a conductive material such as Ag or low melting glass in an organic vehicle for imparting viscosity by screen printing or the like. A conductive composition formed by baking a patterned insulating substrate in an atmosphere of 300 to 500 ° C. to scatter the organic vehicle and vitrifying the low-melting glass is used as an electrode. is doing.
[0004]
In attaching the grid 9 using the intermediate electrode 6, the grid 9 is first attached to a predetermined position on the glass substrate 1 using the viscosity of the paste.
Then, the glass substrate 1 to which the grid 9 is attached by the conductive paste pattern is baked to melt the low melting point glass in the paste, and the low melting point glass is solidified, so that the grid 9 and the glass substrate 1 are fixed. At the same time, the grid 9 and the grid wiring 2 b are electrically connected by the conductive material in the solidified intermediate electrode 6.
[0005]
Further, an intermediate electrode 6 is used for fixing the grid 9 to the glass substrate 1 and electrically connecting it to the grid wiring 2b. First, the intermediate electrode 6 is composed of a conductive material composed of 36.7 wt% Ag particles and 20 wt% Al particles, a low melting point glass, lead titanate (43.3 wt%), and a metal oxide pigment. Then, a conductive paste kneaded in an organic vehicle or the like is formed on the electrode pattern by a screen printing method or the like.
Next, after fixing the grid with the conductive paste, the grid 9 is fixed on the glass substrate 1 by the intermediate electrode 6 obtained by cooling after baking at 300 to 500 ° C.
By doing so, the technique which reduced the generation | occurrence | production of the crack of a glass substrate is disclosed. (For example, refer to Patent Document 1.)
[0006]
Further, as the conductive paste, Ag powder, a conductive material in which 10 to 100 wt% of the graphite powder is combined to 40 wt% with respect to the Ag powder, Pb—Si—Zn—B based glass, an organic vehicle, etc. A technique in which the occurrence of cracks in a glass substrate is reduced by using a paste that is configured is disclosed. (For example, refer to Patent Document 2.)
[0007]
On the other hand, a conductive material composed of 36.5 to 50 wt% of Ag particles, low melting point glass and lead titanate 39 to 50 wt%, an organic metal 2 to 18 wt%, an organic vehicle, etc. A technique is disclosed that reduces the occurrence of cracks and peeling of the intermediate electrode 6 formed by using a paste and fixing the grid 9 and then firing and cooling at 300 to 500 ° C. (For example, refer to Patent Document 3.)
[0008]
As disclosed in Patent Document 3, in the heat treatment step, the organic vehicle in the conductive paste decomposes and evaporates at about 180 ° C., and the conductive paste is dried and loses its adhesiveness. On the other hand, the softening point of frit glass made of low-melting glass is 320 ° C. or higher. Therefore, in the temperature range during this period, the adhesive force due to the conductive paste acting on the interface between the glass substrate 1 and the grid 9 is significantly reduced.
[0009]
Further, in the heating step, the grid 9 and the glass substrate 1 are also heated and expand, but both have different coefficients of thermal expansion, and as a result, there is a difference in the expansion amount between them. A force exceeding the reduced adhesive force of the conductive composition paste acts on the interface with the grid 9, and the intermediate electrode 6 and the grid 9 are separated from the glass substrate 1.
As countermeasures against peeling caused by cracks in the intermediate electrode 6, a conductive material composed of 36.5 to 50 wt% of Ag particles, low melting point glass and lead titanate 39 to 50 wt% as a filler, and organic metal 2 to 18 wt% %, And a technique for forming the intermediate electrode 6 using a conductive composition paste composed of an organic vehicle or the like.
The grid electrode of the fluorescent display tube fixed by the intermediate electrode 6 was peeled off with a spring alone and the fixing strength was measured. When the grid was peeled off, the intermediate electrode adhered to the grid and was peeled off from the anode substrate.
[0010]
The cracks in the intermediate electrode 6 include soda lime glass having a thermal expansion coefficient of 85 to 90 × 10 ⁻⁷ / ° C., an insulating layer of 65 to 80 × 10 ⁻⁷ / ° C., and 100 × 10 ⁻⁷ / ° C. (at 400 (42% Ni-6% Cr-residual Fe) alloy, SUS 430 alloy, SUS 398 alloy, SUS 343 alloy, and other grid material thin plate interfaces, resulting in an internal strain, which is said to occur.
[0011]
On the other hand, a conductive paste for wiring formed on an insulating substrate that does not contain lead, which is an environmentally hazardous substance, has recently been disclosed. The thickness of the conductive sintered body by the conductive paste for wiring is 10 μm or less. (For example, refer to Patent Documents 5 and 6.)
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-152837 [Patent Document 2]
JP-A-4-269404 [Patent Document 3]
JP-A-7-254360 [Patent Document 4]
Japanese Patent Laid-Open No. 11-329072 [Patent Document 5]
JP 2000-48642 A
[Problems to be solved by the invention]
It is an object of the present invention to obtain a conductive composition that does not cause peeling or cracking without impairing the adhesion and electrical characteristics of the conventional conductive composition to an insulating substrate.
Further, the intermediate electrode is not peeled off and the intermediate electrode and the substrate are not cracked in the intermediate process and the finished product without impairing the adhesion force and electrical characteristics of the conventional conductive composition to the insulating substrate. The object is to obtain a fluorescent display tube using an intermediate electrode 6 made of a conductive composition.
Another object of the present invention is to provide a conductive composition using low melting point glass not containing lead which is an environmentally hazardous substance.
[0014]
[Means for solving the problems]
According to the first aspect of the present invention, the grid wiring 2 a is formed on the upper surface of the glass substrate 1, and the insulating layer 8 provided with the through hole 7 is deposited on the grid wiring 2 a, and the conductive material is formed on the through hole 7. In a fluorescent display tube having an anode substrate in which an intermediate electrode 6 acting as a conductive adhesive is disposed and a foot portion of a grid 9 is fixed by the intermediate electrode 6, the intermediate electrode 6 has a total amount. against it, Ag particles _{10~35vol%, Bi 2 O 3 -B} 2 O 3 based glass 10 to 30 vol%, zircon particles 45~70vol%, conductivity of Cu-Cr-based metal oxide pigment is comprised of 10 vol% a gender composition, the 1 in the Ag powder and the zircon particles volume ratio: 7 to 7: 9 relates to a fluorescent display tube, characterized in that the electrically conductive composition formed from the ratio of.
[0015]
According to a second aspect of the present invention, in the fluorescent display tube according to the first aspect, the conductive composition is 10 to 35 vol% of the Ag particles, and the Bi ₂ O with respect to the total amount of the conductive composition. _{The present} invention relates to a fluorescent display tube characterized in that _3- B ₂ O ₃ glass is 10 to 30 vol%, the zircon particles are 45 to 70 vol%, and the Cu—Cr metal oxide pigment is 10 vol%.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the conductive composition of the present invention will be specifically described, and an example in which the conductive composition is applied to a conductive electrode for a fluorescent display tube will be described. (The structure of the fluorescent display tube will be described with reference to FIG.
[0020]
[Action]
The conductive composition fixed to the upper surface of the insulating substrate and / or the cause of the occurrence of cracks at the interface between the conductive composition and the insulating substrate is that there is a firing step in the fluorescent display tube manufacturing process. It appears to be generated because the conductive composition becomes larger than the thermal expansion of the glass substrate.
Assuming that the thermal expansion coefficient of the glass substrate and the conductive composition needs to be compatible with each other, the inventors of the present application calculated the thermal expansion coefficient of the conductive composition as the thermal expansion coefficient of the soda lime glass substrate. in a 90 × ^{10 -7} / ℃ which can reduce the occurrence of the cracks by adapting to 69.0 × ^{10 -7} /℃~140.0×10 ^-7 / ℃ near to the推慮did.
Therefore, the inventors of the present application searched for a substance having an adhesive force in the conductive composition at a temperature of 300 ° C. or lower at which the low melting point glass is solidified.
[0021]
As a result, it is possible to maintain the adhesive force even in the firing step of forming an electrode made of an electrically conductive composition, and the intermediate electrode 6 for fixing the grid, with Ag having an adhesive property of 300 ° C. or less. I found it.
Furthermore, by using a conductive composition in which a composition containing a filler or metal oxide pigment made of ceramic particles is contained in a larger amount than in the past and using a conductive composition as a conductive material, the thermal expansion coefficient of soda lime glass is increased. We have succeeded in producing a conductive composition with a close composition.
By using the conductive composition as the intermediate electrode 6 of the grid-attached fluorescent display tube, the conductive composition has not been a problem in the past due to the complicated and diversified display contents of the fluorescent display tube. An intermediate electrode 6 having no fine cracks at the interface and peeling of the glass substrate and the grid was obtained.
Details will be described below.
[0022]
Conventionally used PbO-B with respect to the thermal expansion coefficient of the above-mentioned soda-lime glass plate glass having a thermal expansion coefficient of 85 to 90 × 10 ⁻⁷ / ° C. and an insulating layer of 65 to 80 × 10 ⁻⁷ / ° C. The thermal expansion coefficient of ₂ O ₃ system glass is 100 to 120 × 10 ⁻⁷ / ° C., and the thermal expansion coefficient of lead titanate particles is 40 to 65 × 10 ⁻⁷ / ° C., which is larger than that of glass.
Therefore, the PbO—B ₂ O ₃ glass and the low-melting glass not containing lead, which is an environmentally hazardous substance closer to the glass having a thermal expansion coefficient than lead titanate, have a thermal expansion coefficient of 70 to 90 × 10 ⁻⁷ / ° C. The Bi ₂ O ₃ —B ₂ O ₃ low melting point glass and zircon having a thermal expansion coefficient of 35 to 45 × 10 ⁻⁷ / ° C. were used as fillers, and the thermal expansion coefficient was made closer to that of glass. The results are shown below.
[0023]
FIG. 2 is a graph in which fixing strength was measured by firing Ag, Bi ₂ O ₃ —B ₂ O ₃ -based low-melting glass, zircon particles, and metal oxide pigments at 300 ° C. and 350 ° C., respectively. .
First, Ag powder, Bi ₂ O ₃ —B ₂ O ₃ -based low melting glass, zircon particles, and metal oxide pigments, which are main components of the conductive composition of the present invention, are 300 ° C. and 350 ° C., respectively. Then, each sticking strength was measured. As a result, Ag is about 1200 to 1300 [g], indicating that the other low melting glass, filler and inorganic pigment are 30 g or less.
Next, the inventors of the present application conducted extensive studies and repeated experiments. As a result, it was found that when the Ag powder was fired, the surface softened at 212 ° C. and started to be substantially sintered.
This phenomenon is because, although the melting point of Ag is 960 ° C., AgNO ₃ having a melting point of 212 ° C. is contained in a trace amount in the Ag powder because the Ag powder starts to be substantially sintered at 212 ° C. _It was assumed that the adhesion strength could be obtained by sintering No. 3.
In order to confirm the inference, when AgNO ₃ was heated to 444 ° C., it was confirmed that Ag was deposited.
[0024]
Here, the method for measuring the adhesive strength of the conductive paste is to separate inorganic particles such as Ag, low melting point glass, and filler constituting a conductive sintered body having a diameter of 2 mm on the upper surface of soda lime glass which is an insulating substrate. After arranging the kneaded conductive paste in the organic vehicle, the conductive composition is fired at a predetermined temperature to form conductive compositions having a height of 0.5 mm, 0.7 mm, 1.0 mm, and 2 mm.
Push-pull gauge when the conductive composition is peeled off by applying a pressing force in parallel to the surface of the insulating substrate by using a push-pull gauge while fixing the insulating substrate. Was used as the fixing strength. (When measuring the fixing strength of the conductive composition, it was measured by the same measuring method.)
[0025]
Next, in order to investigate the cause of peeling of the conductive composition from the substrate, for forming a conductive composition that is a conventional conductive electrode,
(1) Ag content,
(2) Lead titanate content,
In view of the above, the adhesive strength of the conductive composition of the present invention in the form of a paste (B) and the conventional conductive paste A were prepared and compared.
[0026]
(A) A conductive composition paste using only Ag as a conductive material.
Conductive material composed of 29.9 vol% Ag particles, 32.3 vol% low melting glass, 13.5 vol% zircon filler, 24.3 vol% metal oxide pigment, 1-5 wt% ethyl cellulose and other binders Is an electrically conductive composition paste formed by kneading in an organic vehicle obtained by dissolving in an organic solvent such as terpineol.
[0027]
(B) A conductive composition paste in which the composition ratio of filler to Ag is improved by increasing the amount of Ag as a conductive material.
Specifically, a conductive material composed of 22.5 vol% of Ag particles, 15 vol% of low-melting glass, 52.5 vol% of zircon as a filler, 10 vol% of pigment, 1-5 wt% of ethyl cellulose and other binders are terpineol. A conductive paste formed by kneading in an organic vehicle dissolved in an organic solvent such as
[0028]
FIG. 3 is a diagram showing the fixing strength when the conductive pastes A and B are applied to the upper surface of soda lime glass and then fired at 100 ° C. to 500 ° C. to fire the fixing force.
As a result, what was fixed by the binder up to about 100 ° C. to 200 ° C. was lost due to the high temperature in the vicinity of 300 to 350 ° C., and the low melting point glass was not yet vitrified, so the fixing force was not sufficient. It shows that the adhesion is weak, and that when the temperature is raised to 350 to 500 ° C., the low melting point glass is vitrified to increase the fixing force.
[0029]
FIG. 4 is a diagram showing the fixing strength when the conductive pastes A and B are applied to the upper surface of soda lime glass and then fired at 300 ° C. and 350 ° C. to fire the fixing force.
The adhesion force of firing at 300 to 350 ° C. is a temperature at which the grid starts to thermally deform and stretches, and a load is applied to the adhesion interface between the intermediate plate and the substrate. The amount of Ag as a conductive material is increased by increasing the filler. Sample B of the present invention with reduced overall conductive material is the strongest at about 90 g when fired at 300 ° C. and about 110 g when fired at 350 ° C.
[0030]
If the electrical resistivity of the grid fixing intermediate electrode 6 of the fluorescent display tube exceeds 10 Ω / □, the voltage applied to the grid decreases due to the resistance of the intermediate electrode 6 and the display becomes dark. Therefore, when the intermediate electrode 6 is used, it is desirable that the electric resistance value is 10Ω / □ or less.
[0031]
A composition ratio of Bi ₂ O ₃ —B ₂ O ₃ -based low melting glass having a thermal expansion coefficient of 70 to 90 × 10 ⁻⁷ / ° C. and zircon of 35.0 to 45.0 × 10 ⁻⁷ / ° C. as a filler. Adjust
When the composition ratio of Ag having a thermal expansion coefficient of 197.0 × 10 ⁻⁷ / ° C. is changed by 0 to 100%, the conductivity is increased so that the thermal expansion coefficient becomes larger than 65.0 × 10 ⁻⁷ / ° C. The electrical resistivity of the conductive composition and the thermal expansion coefficient of the sintered body were examined.
The pigment was made constant at 10.0 vol% because antireflection of the conductive composition, such as external light, and the thermal expansion of the conductive composition were adjusted in cooperation with the filler.
If 10.0 vol% of the pigment is contained, a conductive composition having a desired coefficient of thermal expansion can be obtained even when there is no filler.
A method of printing an electrically conductive composition paste formed by kneading the inorganic solid in an organic vehicle obtained by dissolving 1 to 5 wt% of ethyl cellulose or other binder in an organic solvent such as terpineol on the upper surface of soda lime glass After the formation by coating, etc., the conductive composition was prepared by baking at 350 ° C. and 450 ° C., and the electrical resistivity and thermal expansion coefficient of the conductive composition were determined.
[0032]
[Table 1]
The table | surface which shows an electrical resistivity, a thermal expansion coefficient, and fixed strength when the composition ratio of Ag is made into 10% increments in the range of 0-100 vol%.

From Table 1, when the Ag content is 10 vol% or more, the electrical resistivity is 10 Ω / □ or less.
[0033]
If the Ag ratio is 10 vol% or more, a fixing strength of 80 g can be obtained by baking at 350 ° C. and 1000 g or more can be obtained by baking at 450 ° C., which is sufficient as an intermediate process of the fluorescent display tube and a fixing strength of the finished product. It was.
The grid of the fluorescent display tube produced using the conductive composition (A) described above was peeled off with a spring alone, and the fixing strength was measured. The fixing strength at 450 ° C. was 180 g, and it was cooled after firing at 450 ° C. The intermediate electrode 6 thus formed adhered to the grid when the grid was peeled off, and was peeled off from the anode substrate.
[0034]
On the other hand, when a fluorescent display tube using the conductive composition of the present invention was prepared and a fixing strength test was performed by peeling off the grid with only a spring, the fixing strength at 450 ° C. was 180 g or more.
When the grid fixed by the intermediate electrode 6 formed by baking after cooling at 450 ° C. was peeled off, only the grid was detached and fixed to the anode substrate and did not peel off.
Further, when the conductive composition of the present application was used, peeling of the intermediate electrode 6 and cracks on the substrate side were also greatly reduced.
When the Ag content exceeds 70 vol%, the thermal expansion coefficient becomes 157.3 × 10 ⁻⁷ / ° C. or more, which indicates that cracking occurs when the conductive electrode is formed on the upper surface of soda lime glass.
From the above, it is shown that the Ag content is preferably 10 to 60 vol%, preferably 10 to 35 vol%.
[0035]
Next, in order to determine the composition range of the content of the low-melting glass, when the pigment content is fixed at 10 vol% and the Ag content is 10 to 60 vol%, the thermal expansion coefficient is 60 ×. The composition ratio of the low-melting glass is changed so as to be larger than 10 ⁻⁷ / ° C., and a conductive paste is prepared by combining Ag, filler and pigment, and the conductive paste is applied to the upper surface of the glass substrate and then fired at 450 ° C. Tables 2 to 7 show the results of measuring the electrical resistance, the thermal expansion coefficient, and the fixing strength.
[0036]
[Table 2]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 10 vol%, and changing content of a low melting glass, a thermal expansion coefficient, and fixed strength.

[0037]
[Table 3]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 20 vol%, and changing content of a low melting glass, a thermal expansion coefficient, and fixed strength.

[0038]
[Table 4]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 30 vol%, and changing content of a low melting glass, a thermal expansion coefficient, and fixed strength.

[0039]
[Table 5]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 40 vol%, and changing content of a low melting glass, a thermal expansion coefficient, and fixed strength.

[0040]
[Table 6]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 50 vol%, and changing the content of a low melting glass, a thermal expansion coefficient, and adhering strength.

[0041]
[Table 7]
The table | surface which shows the electrical resistance at the time of fixing the content rate of Ag to 60 vol%, and changing content of a low melting glass, a thermal expansion coefficient, and a fixed strength.

[0042]
From Table 2 to Table 7, when the content of the low melting point glass is less than 10 vol%, the adhesive strength is not obtained because it is less than 100 g, and when it exceeds 70 vol%, the thermal expansion coefficient is 148.4 × 10 ^{−. 7} / ° C. indicates that the content of the low melting point glass is preferably 10 vol% to 70 vol%.
Next, in order to obtain the optimum values of the filler and pigment content, the Ag content is set to 10 vol% of the lower limit value and 60 vol% of the upper limit value, and the content of the low melting point glass is set to 10 vol% of the lower limit value and The upper limit is set to 30 vol%, and the pigment is fixed to 10 vol% to prepare a conductive paste. The conductive paste is applied to the upper surface of the glass substrate and then baked at 350 ° C. and 450 ° C. to obtain electric resistance, thermal expansion coefficient, and fixing strength. The results of measuring are shown in Table 8.
[0043]
[Table 8]
The table | surface which calculates | requires the optimal value of content of a pigment and a filler.

Table 8 shows that the filler has a synergistic effect with the pigment, and even if it contains 70 vol%, if it contains 10 vol% of Ag and glass, it functions as an intermediate electrode as a conductive composition. Yes.
[0044]
[Table 9]
Table for obtaining a weight ratio of silver powder and low expansion filler powder of conductive composition

Table 9 shows that the amount of glass powder is constant at 20 vol%, which is smaller than before, the Ag powder is changed between 10 to 60 vol%, and the amount of zircon powder (low melting point filler) is adjusted to adjust the amount of glass powder after firing. The crack state of the board | substrate was investigated when the electrically conductive composition created so that a thermal expansion coefficient might become larger than 60 * 10 < ^-7 > / degreeC was used as an intermediate electrode.
Using the aforementioned low melting glass Bi ₂ O ₃ -B ₂ O ₃ low melting glass and zircon as a filler, the thermal expansion coefficient of the conductive composition Ag powder and the low expansion filler powder If the composition ratio of Ag powder and low expansion filler powder is a ratio of 1: 7 to 11: 5 by weight, it indicates that there is no practical problem.
[0045]
From the above, a conductive paste was prepared by kneading Ag: 10-60 Vol%, low melting glass: 10-80 Vol%, filler: 0-70 Vol%, pigment: 5-80 Vol%, and the conductive paste was 300- when firing at 500 ° C., and a surface resistance of 2 [Omega / □ or less, the conductive composition of the thermal expansion coefficient 62.7 × ^{10 -7} /℃~133.35×10 ^-7 / ℃ was obtained.
[0046]
As for the particle size of the said Ag particle, low melting glass, and a filler, 1-20 micrometers is preferable. If the particle size is too large, the compression when the low-melting glass and Ag particles are melted is lowered and the low efficiency is increased, and it passes through the screen opening of 60 μm □ that is usually used for screen printing. It becomes difficult.
If the particle size is too small, the particles will be packed densely. Therefore, the binder between the particles is not preferable because it forms blisters (cavities) during firing and the adhesive strength becomes weak.
[0047]
The shape of the Ag particles is preferably a flake shape. The reason is that, in the case of flakes, when the low melting point glass is melted, the Ag particles are brought into surface contact to lower the resistance.
When the low melting point glass and the filler are blended only in the form of flakes, the thixo ratio increases and workability deteriorates. Moreover, in order to obtain an appropriate leveling property, the printability can be improved by using a paste combined with a spherical shape.
[0048]
As an application example of the present invention, a fluorescent display tube employing an intermediate electrode 6 used as a conductive adhesive for fixing a grid electrode for a fluorescent display tube will be described with reference to FIG.
On the upper surface of the glass substrate 1, patterns of wiring conductors 2a and 2b are disposed.
The wiring conductor 2b includes a grid wiring 2a connected to the grid electrode 9 and leads 15 extending outside the envelope, and an anode wiring 2a connected to the anode 5 composed of the anode conductor 3 and the phosphor 4. .
[0049]
An insulating layer 8 is deposited on the wiring 2 by a screen printing method. The insulating layer 8 is provided with a through hole 7 at a position of the anode 5 and a position where the grid 9 and the grid wiring 2b are connected. The insulating layer 8 is mixed with a black pigment and acts as a black background.
A phosphor layer 4 is deposited on the anode conductor 3 formed by applying a graphite paste on the through hole 7 at the end of the anode wiring 2a to form the anode 5.
Further, an intermediate electrode 6 acting as a conductive adhesive is disposed on the through hole 7 at the end of the grid wiring 2b in the envelope, and a foot portion of the grid 9 is embedded and fixed thereto. ing.
[0050]
The intermediate electrode 6 is composed of 20.0 to 24.0 vol% (preferably 22.5 vol%) of Ag powder having a particle diameter of 1 to 20 μm as a conductive material, and is formed as a frit glass constituting a part of an adhesive component. the _Bi 2 _O 3 _-B 2 _{O 3} based low-melting glass diameter 1~20μm 12.5~20.0vol% (preferably 15 vol% is), 48.5~55.0vol% zircon as a filler (preferably 52.5 vol%), and a conductive composition comprising 7.5 to 14.5 vol% (preferably 10 vol%) of a Cu-Cr pigment having a diameter of 1 to 20 μm as a pigment in an organic solvent such as terpineol. An organic vehicle for making a paste formed by dissolving 1 to 5% of a binder such as ethyl cellulose for improving printability is used as a conductive paste using about 6 vol% as in the prior art.
[0051]
Next, the case where the grid 9 is fixed to the intermediate electrode 6 will be described.
The conductive paste containing the conductive composition is applied by screen printing, and then the grid 9 is fixed to the anode substrate by decomposing and evaporating the organic components of the conductive paste in a state where the grid 9 is placed. .
In this way, an anode substrate is completed in which the anode 5 having a phosphor layer on the surface and the grid 9 disposed above the anode are disposed.
[0052]
The front plate 13 and the side plate 14 are made of a low-melting glass with a part of the anode substrate completed in the above-described process, and a vacuum vessel is formed inside. A fluorescent display tube comprising the intermediate electrode 6 to be formed, a cathode for emitting thermoelectrons, and a metal lead 15 for inputting an electric signal from the outside is constructed, and a fluorescent display tube having a high vacuum inside is completed.
[0053]
Due to the expanded use of fluorescent display tubes, a layer 11 such as SiO ₂ is provided between the upper surface of the glass substrate and the insulating layer, or a crystalline glass layer 12 is provided on the upper surface of the conductive composition (intermediate pattern). is there.
In this case , cracks may occur when forming the SiO ₂ layer 11 used to shield Na ions in soda lime glass or applying the crystallized glass 12 on the intermediate conductive composition. Is likely to occur.
[0054]
In the fluorescent display tube using the above-mentioned conductive composition for the intermediate electrode 6 of the fluorescent display tube, the intermediate electrode 6 was not cracked, and the anode substrate was not cracked.
Further, the conductive composition having a thickness of 1.0 mm provided on the anode substrate of the fluorescent display tube was not peeled off, and no cracks on the substrate side were generated.
Furthermore, the connection reliability can be further improved by connecting the metal lead 15 to the terminal electrode 16 formed on the upper surface of the wiring conductor with the conductive composition of the present invention applied to the wiring conductor formed in the terminal portions of the wiring conductors 2a and 2b. Can be improved.
[0055]
【effect】
The effects of the present invention are as follows.
The effect obtained by obtaining a conductive sintered body that can be applied to the case where a thick film of 300 μm or more is formed without cracking or peeling is significant in the industry.
Further, the effect of preventing the substrate cracking and peeling at the interface with the fine intermediate pattern, which has been a problem in the past due to the complicated and diversified display contents of the fluorescent display tube, is industrially significant.
In addition, the effect obtained by providing the thick conductive composition using the low-melting glass not containing lead, which is an environmentally hazardous substance, is large industrially.
[0056]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a conventional grid-attached fluorescent display tube. FIG. 2 shows 300 parts of Ag, Bi ₂ O ₃ —B ₂ O ₃ low melting point glass, zircon particles, and metal oxide pigments. Fig. 3 is a graph showing the fixing strength measured by baking at 350 ° C and 350 ° C. Fig. 3 shows a state in which the conductive pastes A and B are applied to the upper surface of soda lime glass and then baked at 100 ° C to 500 ° C. The figure which shows fixation strength.
FIG. 4 is a view showing the fixing strength when the conductive pastes A and B are applied to the upper surface of soda lime glass and then fired at 300 ° C. and 350 ° C. to fire the fixing force.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2a ... Anode wiring 2b ... Grid wiring 3 ... Anode conductor 4 ... Phosphor 5 ... Anode 6 ... Intermediate electrode 7 ... Through hole 8 .. Insulating layer 9 ... Grid 10 ... Cathode 11 ... SiO2 layer 12 ... Crystalline glass 13 ... Front plate 14 ... Side plate 15 ... Metal lead 16 ... Terminal electrode

Claims (2)

A grid wiring 2 a is formed on the upper surface of the glass substrate 1, and an insulating layer 8 provided with a through hole 7 is deposited on the grid wiring 2 a, and acts as a conductive adhesive on the through hole 7. In a fluorescent display tube having an anode substrate in which an attached electrode 6 is disposed and a foot of a grid 9 is fixed by the intermediate electrode 6,
The intermediate electrode 6 is composed of 10 to 35 vol% Ag particles, 10 to 30 vol% Bi ₂ O ₃ —B ₂ O ₃ glass, 45 to 70 vol% zircon particles, and Cu—Cr metal based on the total amount. The conductive composition is composed of 10 vol% oxide pigment,
Wherein 1 Ag powder and said zircon particles volume ratio: 7 to 7: 9 fluorescent display tube, characterized in that the electrically conductive composition formed from the ratio of. A grid wiring 2 a is formed on the upper surface of the glass substrate 1, and an insulating layer 8 provided with a through hole 7 is deposited on the grid wiring 2 a, and acts as a conductive adhesive on the through hole 7. In a fluorescent display tube having an anode substrate in which an attached electrode 6 is disposed and a foot of a grid 9 is fixed by the intermediate electrode 6,
The intermediate electrode 6 is composed of 20.0 to 24.0 vol% of Ag powder having a particle diameter of 1 to 20 μm and 12.5 to 20.0 vol of Bi ₂ O ₃ —B ₂ O ₃ glass having a particle diameter of 1 to 20 μm. %, Zircon particles are 48.5 to 55.0 vol%, and a Cu—Cr metal oxide pigment having a particle diameter of 1 to 20 μm is a conductive composition comprising 7.5 to 14.5 vol%. Fluorescent display tube.

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