JP2004039882A

JP2004039882A - Chip type thermistor and its manufacturing method

Info

Publication number: JP2004039882A
Application number: JP2002195416A
Authority: JP
Inventors: Shoichi Muramoto; 村本　昭一; Masakuni Tateno; 立野　昌邦; Yoji Ueda; 植田　要治
Original assignee: Tateyama Kagaku Kogyo Co Ltd
Current assignee: Tateyama Kagaku Kogyo Co Ltd
Priority date: 2002-07-04
Filing date: 2002-07-04
Publication date: 2004-02-05

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip type thermistor with a small size and high accuracy and to provide its manufacturing method. <P>SOLUTION: There are provided, on an insulating substrate 1, a pair of distal electrodes 2, 3; a series of the thermistors 4 straddling between the distal electrodes 2, 3, and an intermediate electrode 5 that sandwiches a thermistor body 4 and is positioned opposite to the distal electrodes 2, 3. A bypass resistance value between the pair of the distal electrodes 2, 3 is made to be sufficiently larger than the sum of resistance values between the distal electrode 2 and the intermediate electrode 5 and that between the distal electrode 3 and the intermediate electrode 5. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、チップ型サーミスタ及びその製造方法に関する。
【０００２】
【従来の技術】
近年、コンピュータ及びその周辺機器の普及、並びにそれらの高性能化によって、回路基板に用いられる抵抗器等の電子部品においても、その抵抗値の高精度化が第一に求められている。前記抵抗器は熱により抵抗値が変動するという短所があり、所望の抵抗値への高精度な調整が困難という課題があった。
【０００３】
【発明が解決しようとする課題】
本発明は、上記実情に鑑みて成されたものであって、高精度でチップサイズの小さいチップ型サーミスタとその製造方法の提供を目的とする。
【０００４】
【課題を解決するための手段】
上記目的を達成するために、本発明のうち請求項１記載のチップ型サーミスタは、絶縁基板上に、対をなす端部電極と、前記両端部電極間にまたがる一連のサーミスタ体と、当該サーミスタ体を挟んで前記端部電極に対向する中間電極とを備え、前記対をなす端部電極間のバイパス抵抗値は、一方の端部電極と中間電極間の抵抗値と、他方の端部電極と中間電極間の抵抗値との和よりも、十分大きい値にすることを特徴とする。
【０００５】
ここで、「バイパス抵抗値」とは、中間電極を介さない場合の、サーミスタ体を挟んだ端部電極間の抵抗成分である。また、「十分大きい値」とは、一方の端部電極と中間電極間の抵抗値と、他方の端部電極と中間電極間の抵抗値との和からなるサーミスタ全体の定数に影響を与えない程度に大きい値をいう。
尚、前記サーミスタ体を挟む端部電極及び中間電極の上下関係は、適宜変更可能である。即ち、所定の大きさの絶縁基板と、前記中間電極に重なる一連のサーミスタ体を前記絶縁基板上に具備し、当該サーミスタ体の上に各々前記中間電極を具備した構成でも良い。
【０００６】
請求項１記載のチップ型サーミスタを得るための製造方法は、請求項２記載のように、所定の大きさの絶縁基板上に、一対の端部電極を形成する端部電極形成工程と、前記両端部電極間にまたがる一連のサーミスタ体を形成するサーミスタ体形成工程と、両端部電極間にまたがって形成されたサーミスタ体上に、前記両端部電極に対向する中間電極を形成する中間電極形成工程と、サーミスタ全体が所定抵抗値と成るよう前記サーミスタ体上の前記中間電極の一部を切削する中間電極切削工程とを備えていることを特徴とする。
【０００７】
また、請求項１記載のチップ型サーミスタを得るために他の製造方法として、請求項３記載のように、所定の大きさの絶縁基板上の中央部に中間電極を形成する中間電極形成工程と、前記中間電極に重なる一連のサーミスタ体を形成するサーミスタ体形成工程と、前記サーミスタ体の上に、前記中間電極と対向する対を成す端部電極を形成する端部電極形成工程と、サーミスタ全体が所定抵抗値と成るよう前記サーミスタ体上の前記端部電極の一部を切削する端部電極切削工程とを備えるていることを特徴とする。
【０００８】
【発明の実施の形態】
以下、本発明によるチップ型抵抗器の実施形態を、その製造方法と共に図１から図１１を参照して説明する。
【０００９】
ここで示すチップ型抵抗器の製造方法は、アルミナ製の絶縁基板（以下、絶縁基板１と記す。）上に、予めＶ字状の分割溝を碁盤目状に刻設することによって等面積同形状の区画された単位領域を複数形成し、各単位領域に一つの抵抗器本体を、導電ペーストや抵抗ペースト、或いはガラス等の絶縁ペーストを印刷し焼成することによって形成し、適宜、分割工程を経ながら外部電極形成及び仕上げのメッキ処理を施すという多数一括製造方法を採用している。
【００１０】
始めに、図１に示す様な端部電極２，３が中間電極５より下にある場合の本発明によるチップ型抵抗器の第一の実施形態例をその製造方法と共に説明する。まず、端部電極形成工程で、絶縁基板１の上面に端部電極の電極パターンを形成する（図７の（イ）参照）。本実施の形態では、上述したように絶縁基板の単位領域毎に両端部電極２，３となるパターンを、印刷又はエッチング等の方法でそれぞれ形成する。そして例えば８５０℃で約十分間加熱焼成することにより各端部電極２，３が形成される。
【００１１】
そして、サーミスタ体形成工程でこのようにしてできた端部電極２及び端部電極３上に印刷等でサーミスタ体４となるパターンを形成し、これを例えば８５０℃で約十分間加熱焼成することによりサーミスタ体４が形成される。このサーミスタ体４は単位領域毎に端部電極２及び端部電極３間にまたがり一連に形成される（図７の（ロ）参照）。
【００１２】
続いて中間電極形成工程で、図７の（ハ）に示す様に、サーミスタ体４の上面にサーミスタ体４のほぼ全面を覆う中間電極５のパターンを印刷又は、エッチング等の方法で形成する。そして例えば８５０℃で約十分間加熱焼成することにより中間電極５が形成される。
【００１３】
前記サーミスタ体形成工程と前記中間電極形成工程により、一方の端部電極２と中間電極５間、及び他方の端部電極３と中間電極５間、並びに一方の端部電極２と他方の端部電極３間には抵抗値が出現するが、図４に示す様に、一方の端部電極２と他方の端部電極３間の抵抗成分は、端部電極２と中間電極５間、及び端部電極３と中間電極５間の抵抗成分のいずれよりも十分大きい値とするので、前記端部電極２と端部電極３間の抵抗成分は無視出来るものとなる。
【００１４】
また、一方の端部電極２と中間電極５間と、他方の端部電極３と中間電極５間の両抵抗成分を比較して、前記両抵抗成分が等しくなる様、前記端部電極形成工程及び前記中間電極形成工程において、端部電極２と中間電極５の対向面積及び、端部電極３と中間電極５の対向面積が調整されている（図３の斜線部参照）。
【００１５】
なお、上述した例では、両端部電極２，３及びサーミスタ体４の焼成、並びに中間電極５の焼成を各工程毎にそれぞれ別個に行う例を示したが、各形成工程において焼成を行わずにパターン形成のみを行い、乾燥後に一括して焼成してもよい。
【００１６】
そして、次に中間電極切削工程を実行する。一方の端部電極２と中間電極５または他方の端部電極３と中間電極５の重なり合う部分の面積を（Ｓ）、この部分のサーミスタ体４の膜厚を（ｔ）、サーミスタ体の比抵抗を（ρ）とすると、得られる抵抗値Ｒは、Ｒ＝ρ（ｔ／Ｓ）となる。従って、トリミング前の初期抵抗値を測定しておき、目的とする抵抗値を得るべく前記面積（Ｓ）を計算により割り出して、実際に切削すべき面積を求め、この求めた量だけ中間電極５におけるサーミスタ体４と一方の端部電極２が重合する部分や、中間電極５におけるサーミスタ体４と他方の端部電極３が重合する部分を切削することにより、所望の抵抗値とできる（図７の（ニ）参照）。
【００１７】
なお、この中間電極切削工程を本実施例ではレーザトリミングで行うものとする。そして、切削の深さは、少なくとも中間電極５を貫通する深さを要し、たとえその深さがサーミスタ体４にまで至ったとしても前記端部電極２，３の表面に至らない深さとし、前記中間電極５と前記端部電極２，３との間の短絡を防止する。前記所望の抵抗値に調整する場合は、前記両抵抗成分のうちどちらか一方の抵抗成分を構成する中間電極５の領域を大きく切削して粗調整を行い、他方の抵抗成分を構成する前記中間電極５の領域を小刻みに切削して微調整を行う。
【００１８】
次に、前記中間電極形成行程で形成した中間電極５の全体を、単位領域毎の両端部電極２，３を露出した状態で、ガラスを素材とした保護膜６を被覆する保護膜形成工程を行う。この例では、横分割溝にそって連続した帯状の膜を以て横方向に連続した複数の単位領域の保護膜６を一連に形成する。続いて、横分割溝を以て、横並びにチップ抵抗器が連結したブロック単位で分割する分割工程を行う。
【００１９】
更に、前記分割工程により分離したブロックの分断面、即ち、各チップ型サーミスタの両端面に導電塗料を定着させ、絶縁基板１上の端部電極２の露出面から、絶縁基板１の端面と、更に絶縁基板１裏面の前記端部電極２に対向した領域に亘る一体物の外部電極８と、絶縁基板１上の端部電極３の露出面から絶縁基板１の端面と、更に絶縁基板１裏面の前記端部電極３に対向した領域に亘る一体物の外部電極８を形成する外部電極形成工程を行う。この工程は、前記ブロックを構成する全てのチップ抵抗器の端面について一連の外部電極８を形成する形で行われる。当該外部電極８は、例えば、銀とガラスとバインダ樹脂を混合してペースト化した導電素材を被覆したものである。
【００２０】
そして、最後に、当該分割工程で、上記工程を終えたブロックを更にチップ型サーミスタ一個毎に分割し、外部電極形成工程を経て構築された外部電極８の表面にメッキ膜７を形成する為、必要に応じてニッケルメッキ処理を行った後に、半田メッキ処理あるいは錫メッキ処理を施すメッキ工程を施して、図１０に示す様な回路基板へ実装する際の定着性を高めた個々のチップ型サーミスタが完成する（図８の（へ）乃至（チ）参照）。
【００２１】
この様にして製作した本実施例のチップ型サーミスタは、例えば、幅１．２ｍｍ、長さ２．０ｍｍ、絶縁基板１の厚さ０．６ｍｍ、電極部の厚さ１０μｍ、サーミスタ体４の厚さ４０μｍ程度に形成する。また、絶縁基板上に形成される端部電極２と端部電極３間の長さ約０．５ｍｍとする。
【００２２】
上記実施形態によるチップ型サーミスタの抵抗は製造工程上、図６の（イ）に示す如くバイパス抵抗とサーミスタＡとサーミスタＢの３つの抵抗成分から成るが、前記の如く、前記端部電極２，３間のバイパス抵抗値は無視できるものであるから、図４に示す如く端部電極２と中間電極５間の抵抗成分（サーミスタＡ）及び端部電極３と中間電極５間の抵抗成分（サーミスタＢ）から成る中間電極５を介した抵抗成分のみで考えることができ、等価回路図で表すと図６の（ロ）の構成となる。
【００２３】
本実施形態例ではレーザートリミング処理を施して抵抗値の調節を行うが、上記構成を採用することにより、電極間に挟まれたサーミスタ体４に熱による悪影響を殆ど与えることなく抵抗値調節ができることは勿論、粗調整抵抗成分の調整と、微調整抵抗成分の調整とを分割して行うことにより、抵抗値調整の高精度化が可能であり、レーザートリミング時の温度変化による抵抗値の変動を少なく出来る。また、端部電極２と中間電極５間のサーミスタ体４及び端部電極３と中間電極５間のサーミスタ体に、それぞれ印可される電圧が分割して印可される為に薄膜化も可能であり、チップ全体を薄くできる。
【００２４】
次に、図２に示す如く中間電極５が端部電極２，３より下にある場合のチップ型サーミスタの第二の実施形態例を図９に示す製造方法と共に説明する。まず、中間電極形成工程で、絶縁基板１の単位領域毎に中間電極５となる電極パターンを形成する（図９の（イ）参照）。本実施の形態では、上述したように絶縁基板１の単位領域の上面に中間電極５を印刷又は、エッチング等の方法で形成する。そして例えば８５０℃で約十分間加熱焼成することにより中間電極５が形成される。
【００２５】
そして、サーミスタ体形成工程で、前記中間電極形成工程で形成した絶縁基板１の単位領域毎に、前記中間電極５に重なり合うサーミスタ体４となるパターンを印刷等で形成する（図９の（ロ）参照）。そして例えば８５０℃で約十分間加熱焼成することにより、サーミスタ体４のパターンが形成される。
【００２６】
続いて端部電極形成工程で、図９の（ハ）に示す様に、サーミスタ体４の上面に、端部電極２及び端部電極３となるパターンを当該サーミスタ体４の端部及び前記単位領域毎の端部に亘って印刷又は、エッチング等の方法で形成する。そして例えば８５０℃で約十分間加熱焼成することにより、端部電極２と端部電極３が形成される。
【００２７】
これにより、端部電極２と中間電極５間及び端部電極３と中間電極５間、並びに端部電極２と端部電極３間には抵抗成分が出現するが、図５に示す様に、両端部電極２，３間の抵抗成分は、一方の端部電極２と中間電極５間及び他方の端部電極３と中間電極５間の抵抗成分のいずれよりも十分大きい値とするので、前記第一の実施形態同様無視出来るものである。
【００２８】
また、一方の端部電極２と中間電極５間の抵抗値と、他方の端部電極３と中間電極５間の抵抗値とが等しくなるように、前記端部電極形成工程及び前記中間電極形成工程において、端部電極２と中間電極５の対向面積と、端部電極３と中間電極５の対向面積とが等しくなる様調整されている。
【００２９】
なお、上述した例においても、端部電極２、端部電極３及び中間電極５の焼成、並びにサーミスタ体４の焼成を各工程毎にそれぞれ別個に行う例を示したが、本実施例はこの例に限るものではなく、各形成工程では焼成を行わずにパターン形成のみを行い、乾燥後に一括して焼成してもよい。
【００３０】
そして、次に端部電極切削工程を実行する。前記端部電極切削工程は前記中間電極切削工程と同様に、はじめに初期抵抗値を測定しておき、切削する面積を計算により割り出して実際の切削の面積を求め、端部電極２や端部電極３がそれぞれ中間電極５と重合する部分を切削する（図９の（ニ）参照）。
【００３１】
尚、この第二の実施形態においても、所望の抵抗値に調整する場合は、前記両抵抗成分のうちどちらか一方の抵抗成分を構成する前記端部電極２の領域を大きく切削して粗調整を行い、他方の抵抗成分を構成する前記端部電極３の領域を小刻みに切削して微調整を行う。また、上記実施形態における等価回路図は、前記第一の実施形態の等価回路図と同様である（図６の（ロ）参照）。また、切削の深さは、少なくとも端部電極２，３を貫通する深さを要し、たとえその深さがサーミスタ体４にまで至ったとしても前記中間電極５の表面に至らない深さとして、前記端部電極２，３と中間電極５との間の短絡を防止する。
【００３２】
後に、前記第一の実施形態と同様の、保護膜形成工程、外部電極形成工程、分割工程、メッキ工程を経て、図１１に示す様なチップ型サーミスタが複数完成する（図８の（ホ）乃至（チ））。
【００３３】
【発明の効果】
以上の如く本発明によるチップ型サーミスタを使用すれば、サーミスタ体の抵抗値がトリミング時の熱により変動することを低減でき、所望の抵抗値への高精度な調整が可能である。更に、等価的に直列接続された各サーミスタにかかる印可電圧が分割されることによりチップの薄膜化が実現でき、高精度で信頼性の高いサーミスタチップを提供できる。
【図面の簡単な説明】
【図１】本発明によるチップ型サーミスタの一例を示す側面図である。
【図２】本発明によるチップ型サーミスタの一例を示す側面図である。
【図３】本発明によるチップ型サーミスタの一例を示す平面図である。
【図４】図１の部分的拡大図である。
【図５】図２の部分的拡大図である。
【図６】（イ）（ロ）
本発明によるチップ型サーミスタの等価回路図である。
【図７】（イ）（ロ）（ハ）（ニ）
一般的なチップ型サーミスタの製造方法の一例を示す工程図である。
【図８】（ホ）（ヘ）（ト）（チ）
一般的なチップ型サーミスタの製造方法の一例を示す工程図である。
【図９】（イ）（ロ）（ハ）（ニ）
一般的なチップ型サーミスタの製造方法の一例を示す工程図である。
【図１０】本発明によるチップ型サーミスタの一例を示す側面図である。
【図１１】本発明によるチップ型サーミスタの一例を示す側面図である。
【符号の説明】
１　絶縁基板，２　端部電極，３　端部電極，４　サーミスタ体，
５　中間電極，６　保護膜，７　メッキ膜，８　外部電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chip thermistor and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the spread of computers and their peripheral devices and their high performance, electronic components such as resistors used for circuit boards are also required to have high resistance values first. The resistor has a disadvantage that the resistance value fluctuates due to heat, and there is a problem that it is difficult to adjust the resistance value to a desired value with high accuracy.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and has as its object to provide a highly accurate chip type thermistor having a small chip size and a method of manufacturing the same.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, a chip-type thermistor according to claim 1 of the present invention comprises a pair of end electrodes, a series of thermistors spanning between the both end electrodes on an insulating substrate, and the thermistor. An intermediate electrode opposed to the end electrode with the body interposed therebetween, wherein a bypass resistance value between the pair of end electrodes is a resistance value between one end electrode and the intermediate electrode, and a resistance value of the other end electrode. And a resistance value between the intermediate electrode and the intermediate electrode.
[0005]
Here, the “bypass resistance value” is a resistance component between the end electrodes sandwiching the thermistor body when not passing through the intermediate electrode. The “sufficiently large value” does not affect the constant of the thermistor as a whole, which is the sum of the resistance between one end electrode and the intermediate electrode and the resistance between the other end electrode and the intermediate electrode. A value that is as large as possible.
The vertical relationship between the end electrode and the intermediate electrode sandwiching the thermistor body can be changed as appropriate. That is, a configuration may be adopted in which an insulating substrate of a predetermined size and a series of thermistor bodies overlapping the intermediate electrode are provided on the insulating substrate, and the intermediate electrodes are provided on the thermistor bodies.
[0006]
A manufacturing method for obtaining a chip type thermistor according to claim 1 includes, as described in claim 2, an end electrode forming step of forming a pair of end electrodes on an insulating substrate having a predetermined size; A thermistor body forming step of forming a series of thermistor bodies extending between both end electrodes; and an intermediate electrode forming step of forming an intermediate electrode facing the both end electrodes on the thermistor body formed between the both end electrodes. And an intermediate electrode cutting step of cutting a part of the intermediate electrode on the thermistor body so that the entire thermistor has a predetermined resistance value.
[0007]
Further, as another manufacturing method for obtaining the chip type thermistor according to claim 1, as in claim 3, an intermediate electrode forming step of forming an intermediate electrode at a central portion on an insulating substrate having a predetermined size is provided. A thermistor body forming step of forming a series of thermistor bodies overlapping the intermediate electrode; an end electrode forming step of forming a pair of end electrodes facing the intermediate electrode on the thermistor body; And an end electrode cutting step of cutting a part of the end electrode on the thermistor body so as to have a predetermined resistance value.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a chip-type resistor according to the present invention will be described with reference to FIGS.
[0009]
The method of manufacturing the chip resistor shown here is the same as that described above, in which V-shaped dividing grooves are previously cut in a grid pattern on an insulating substrate made of alumina (hereinafter, referred to as insulating substrate 1). A plurality of unit regions divided in shape are formed, and one resistor main body is formed in each unit region by printing and baking an insulating paste such as a conductive paste or a resistive paste, or glass. A multi-batch manufacturing method is employed in which external electrode formation and finish plating are performed while passing through.
[0010]
First, a first embodiment of the chip-type resistor according to the present invention in which the end electrodes 2 and 3 as shown in FIG. First, in an end electrode forming step, an electrode pattern of an end electrode is formed on the upper surface of the insulating substrate 1 (see FIG. 7A). In the present embodiment, as described above, the patterns to be the both end electrodes 2 and 3 are formed in each unit region of the insulating substrate by a method such as printing or etching. Then, for example, by heating and firing at 850 ° C. for about 10 minutes, the end electrodes 2 and 3 are formed.
[0011]
Then, a pattern to become the thermistor body 4 is formed on the end electrode 2 and the end electrode 3 thus formed in the thermistor body formation step by printing or the like, and this is heated and baked at 850 ° C. for about ten minutes. Thereby, the thermistor body 4 is formed. The thermistor body 4 is formed in a series over the end electrode 2 and the end electrode 3 for each unit area (see FIG. 7B).
[0012]
Subsequently, in the intermediate electrode forming step, as shown in FIG. 7C, a pattern of the intermediate electrode 5 covering almost the entire surface of the thermistor body 4 is formed on the upper surface of the thermistor body 4 by a method such as printing or etching. The intermediate electrode 5 is formed by, for example, heating and firing at 850 ° C. for about 10 minutes.
[0013]
By the thermistor body forming step and the intermediate electrode forming step, between the one end electrode 2 and the intermediate electrode 5, between the other end electrode 3 and the intermediate electrode 5, and between the one end electrode 2 and the other end Although a resistance value appears between the electrodes 3, as shown in FIG. 4, the resistance component between one end electrode 2 and the other end electrode 3 is between the end electrode 2 and the intermediate electrode 5, and between the end electrode 2 and the intermediate electrode 5. The resistance component between the end electrode 2 and the end electrode 3 is negligible because the resistance value between the end electrode 2 and the end electrode 3 is sufficiently larger than any of the resistance components between the part electrode 3 and the intermediate electrode 5.
[0014]
Further, the resistance component between one end electrode 2 and the intermediate electrode 5 and the resistance component between the other end electrode 3 and the intermediate electrode 5 are compared, and the end electrode forming step is performed so that the resistance components are equal. Also, in the intermediate electrode forming step, the facing area between the end electrode 2 and the intermediate electrode 5 and the facing area between the end electrode 3 and the intermediate electrode 5 are adjusted (see the hatched portion in FIG. 3).
[0015]
In the above-described example, the firing of the both-end electrodes 2 and 3 and the thermistor body 4 and the firing of the intermediate electrode 5 are performed separately for each process, but the firing is not performed in each forming process. It is also possible to perform only the pattern formation, and fire it all after drying.
[0016]
Then, an intermediate electrode cutting step is executed next. The area of the portion where one end electrode 2 and the intermediate electrode 5 or the other end electrode 3 and the intermediate electrode 5 overlap is (S), the thickness of the thermistor body 4 in this part is (t), and the specific resistance of the thermistor body is Is (ρ), the obtained resistance value R is R = ρ (t / S). Therefore, the initial resistance value before trimming is measured, the area (S) is calculated by calculation to obtain the desired resistance value, the area to be actually cut is obtained, and the intermediate electrode 5 is obtained by the obtained amount. By cutting the portion where the thermistor body 4 and one end electrode 2 overlap in the above-mentioned and the portion where the thermistor body 4 and the other end electrode 3 overlap in the intermediate electrode 5, a desired resistance value can be obtained (FIG. 7). (D)).
[0017]
In this embodiment, this intermediate electrode cutting step is performed by laser trimming. The cutting depth needs to be at least a depth penetrating the intermediate electrode 5, and even if the depth reaches the thermistor body 4, the cutting depth does not reach the surfaces of the end electrodes 2 and 3. A short circuit between the intermediate electrode 5 and the end electrodes 2 and 3 is prevented. When the resistance value is adjusted to the desired value, the area of the intermediate electrode 5 that constitutes one of the two resistance components is roughly cut to perform coarse adjustment, and the intermediate resistance that constitutes the other resistance component is made. Fine adjustment is performed by cutting the area of the electrode 5 in small increments.
[0018]
Next, a protective film forming step of covering the entire intermediate electrode 5 formed in the intermediate electrode forming step with a protective film 6 made of glass in a state where both end electrodes 2 and 3 for each unit area are exposed. Do. In this example, the protective films 6 in a plurality of unit regions that are continuous in the lateral direction are formed in series with a band-shaped film that is continuous along the horizontal division grooves. Subsequently, a dividing step is performed in which the horizontal dividing groove is used to divide the block into units of blocks to which the chip resistors are connected.
[0019]
Further, a conductive coating material is fixed on the cross-section of the block separated in the dividing step, that is, on both end surfaces of each chip-type thermistor, and from the exposed surface of the end electrode 2 on the insulating substrate 1, the end surface of the insulating substrate 1; Further, an integrated external electrode 8 extending over a region facing the end electrode 2 on the back surface of the insulating substrate 1, an end surface of the insulating substrate 1 from the exposed surface of the end electrode 3 on the insulating substrate 1, and a back surface of the insulating substrate 1 An external electrode forming step of forming an integrated external electrode 8 over a region opposed to the end electrode 3 is performed. This step is performed by forming a series of external electrodes 8 on the end faces of all the chip resistors constituting the block. The external electrode 8 is, for example, coated with a conductive material that is made by mixing silver, glass, and a binder resin into a paste.
[0020]
Finally, in the dividing step, the block after the above step is further divided into chip-type thermistors, and a plating film 7 is formed on the surface of the external electrode 8 constructed through the external electrode forming step. An individual chip type thermistor having an improved fixability when mounted on a circuit board as shown in FIG. 10 by performing a plating process of performing a solder plating process or a tin plating process after performing a nickel plating process as necessary. Is completed (see (f) to (h) in FIG. 8).
[0021]
The chip-type thermistor of this example manufactured in this manner has, for example, a width of 1.2 mm, a length of 2.0 mm, a thickness of the insulating substrate 1 of 0.6 mm, a thickness of the electrode portion of 10 μm, and a thickness of the thermistor body 4. It is formed to a thickness of about 40 μm. The length between the end electrodes 2 and 3 formed on the insulating substrate is about 0.5 mm.
[0022]
The resistance of the chip type thermistor according to the above-described embodiment is composed of a bypass resistor and three resistance components of the thermistor A and thermistor B as shown in FIG. The resistance between the end electrode 2 and the intermediate electrode 5 (thermistor A) and the resistance between the end electrode 3 and the intermediate electrode 5 (thermistor A) as shown in FIG. It can be considered only by the resistance component via the intermediate electrode 5 composed of B), and when represented by an equivalent circuit diagram, the configuration shown in FIG.
[0023]
In this embodiment, the resistance value is adjusted by performing a laser trimming process. However, by adopting the above-described configuration, the resistance value can be adjusted with little adverse effect of heat on the thermistor body 4 sandwiched between the electrodes. Of course, by dividing the adjustment of the coarse adjustment resistance component and the adjustment of the fine adjustment resistance component separately, the accuracy of the resistance value adjustment can be improved, and the fluctuation of the resistance value due to the temperature change during laser trimming can be reduced. Can be reduced. Further, the applied voltage is divided and applied to the thermistor body 4 between the end electrode 2 and the intermediate electrode 5 and the thermistor body between the end electrode 3 and the intermediate electrode 5, so that the film can be thinned. The entire chip can be made thinner.
[0024]
Next, a description will be given of a second embodiment of the chip type thermistor in the case where the intermediate electrode 5 is below the end electrodes 2 and 3 as shown in FIG. 2, together with the manufacturing method shown in FIG. First, in an intermediate electrode forming step, an electrode pattern to be the intermediate electrode 5 is formed for each unit region of the insulating substrate 1 (see FIG. 9A). In the present embodiment, the intermediate electrode 5 is formed on the upper surface of the unit region of the insulating substrate 1 by a method such as printing or etching as described above. The intermediate electrode 5 is formed by, for example, heating and firing at 850 ° C. for about 10 minutes.
[0025]
Then, in the thermistor body forming step, a pattern to be the thermistor body 4 overlapping with the intermediate electrode 5 is formed by printing or the like for each unit area of the insulating substrate 1 formed in the intermediate electrode forming step (FIG. 9 (b)). reference). Then, for example, by heating and firing at 850 ° C. for about 10 minutes, the pattern of the thermistor body 4 is formed.
[0026]
Subsequently, in the end electrode forming step, as shown in FIG. 9C, a pattern to be the end electrode 2 and the end electrode 3 is formed on the upper surface of the thermistor body 4 at the end of the thermistor body 4 and the unit. It is formed by a method such as printing or etching over the end of each region. Then, for example, by heating and baking at 850 ° C. for about 10 minutes, the end electrode 2 and the end electrode 3 are formed.
[0027]
Thereby, a resistance component appears between the end electrode 2 and the intermediate electrode 5, between the end electrode 3 and the intermediate electrode 5, and between the end electrode 2 and the end electrode 3, as shown in FIG. The resistance component between both end electrodes 2 and 3 is set to a value sufficiently larger than any of the resistance components between one end electrode 2 and intermediate electrode 5 and between the other end electrode 3 and intermediate electrode 5. It can be ignored as in the first embodiment.
[0028]
Further, the end electrode forming step and the intermediate electrode forming step are performed such that the resistance between one end electrode 2 and the intermediate electrode 5 is equal to the resistance between the other end electrode 3 and the intermediate electrode 5. In the process, the facing area between the end electrode 2 and the intermediate electrode 5 is adjusted to be equal to the facing area between the end electrode 3 and the intermediate electrode 5.
[0029]
Note that, in the above-described example, the example in which the firing of the end electrode 2, the end electrode 3, and the intermediate electrode 5, and the firing of the thermistor body 4 are separately performed in each process is shown. The present invention is not limited to this example. In each forming step, only pattern formation may be performed without firing, and firing may be performed after drying.
[0030]
Then, an end electrode cutting step is executed. In the end electrode cutting step, as in the case of the intermediate electrode cutting step, an initial resistance value is measured first, an area to be cut is determined by calculation, and an actual cutting area is obtained. 3 cuts a portion that overlaps with the intermediate electrode 5 (see (d) in FIG. 9).
[0031]
Also in the second embodiment, when the resistance value is adjusted to a desired value, the area of the end electrode 2 constituting one of the two resistance components is roughly cut to roughly adjust the resistance value. And fine adjustment is performed by cutting the area of the end electrode 3 constituting the other resistance component in small increments. The equivalent circuit diagram in the above embodiment is similar to the equivalent circuit diagram in the first embodiment (see (b) of FIG. 6). Further, the cutting depth needs to be at least a depth penetrating the end electrodes 2 and 3, and even if the depth reaches the thermistor body 4, the cutting depth does not reach the surface of the intermediate electrode 5. The short circuit between the end electrodes 2 and 3 and the intermediate electrode 5 is prevented.
[0032]
Thereafter, a plurality of chip-type thermistors as shown in FIG. 11 are completed through the same protective film forming step, external electrode forming step, dividing step, and plating step as in the first embodiment (FIG. 8 (e)). Or (H)).
[0033]
【The invention's effect】
As described above, by using the chip-type thermistor according to the present invention, it is possible to reduce the fluctuation of the resistance value of the thermistor body due to heat during trimming, and it is possible to adjust the resistance value to a desired value with high accuracy. Furthermore, by dividing the applied voltage applied to each thermistor connected in series equivalently, the chip can be made thinner, and a highly accurate and highly reliable thermistor chip can be provided.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a chip type thermistor according to the present invention.
FIG. 2 is a side view showing an example of a chip thermistor according to the present invention.
FIG. 3 is a plan view showing an example of a chip thermistor according to the present invention.
FIG. 4 is a partially enlarged view of FIG. 1;
FIG. 5 is a partially enlarged view of FIG. 2;
FIG. 6 (a) (b)
FIG. 3 is an equivalent circuit diagram of the chip thermistor according to the present invention.
FIG. 7 (a) (b) (c) (d)
It is a process drawing showing an example of a manufacturing method of a general chip type thermistor.
FIG. 8 (e) (f) (g) (h)
It is a process drawing showing an example of a manufacturing method of a general chip type thermistor.
FIG. 9 (a) (b) (c) (d)
It is a process drawing showing an example of a manufacturing method of a general chip type thermistor.
FIG. 10 is a side view showing an example of a chip thermistor according to the present invention.
FIG. 11 is a side view showing an example of a chip type thermistor according to the present invention.
[Explanation of symbols]
1 insulating substrate, 2 end electrode, 3 end electrode, 4 thermistor body,
5 intermediate electrode, 6 protective film, 7 plating film, 8 external electrode

Claims

絶縁基板（１）上に、対をなす端部電極（２，３）と、前記端部電極（２，３）間にまたがる一連のサーミスタ体（４）と、当該サーミスタ体（４）を挟んで前記端部電極（２，３）に対向する中間電極（５）とを備え、
前記対をなす端部電極（２，３）間のバイパス抵抗値は、一方の端部電極（２）と中間電極（５）間の抵抗値と、他方の端部電極（３）と中間電極（５）間の抵抗値との和よりも、十分大きい値にすることを特徴とするチップ型サーミスタ。A pair of end electrodes (2, 3), a series of thermistor bodies (4) extending between the end electrodes (2, 3), and the thermistor bodies (4) sandwiched on the insulating substrate (1). And an intermediate electrode (5) facing the end electrodes (2, 3).
The bypass resistance value between the pair of end electrodes (2, 3) includes a resistance value between one end electrode (2) and the intermediate electrode (5), and a resistance value between the other end electrode (3) and the intermediate electrode. (5) A chip-type thermistor characterized in that the value is set to a value sufficiently larger than the sum of the resistance values between (5).

所定の大きさの絶縁基板（１）上に、一対の端部電極（２，３）を形成する端部電極形成工程と、前記端部電極（２，３）間にまたがる一連のサーミスタ体（４）を形成するサーミスタ体形成工程と、端部電極（２，３）間にまたがって形成されたサーミスタ体（４）上に、前記端部電極（２，３）に対向する中間電極（５）を形成する中間電極形成工程と、サーミスタ全体が所定抵抗値と成るよう前記サーミスタ体（４）上の前記中間電極（５）の一部を切削する中間電極切削工程と、を備えることを特徴とするチップ型サーミスタの製造方法。An end electrode forming step of forming a pair of end electrodes (2, 3) on an insulating substrate (1) having a predetermined size, and a series of thermistor bodies (2) extending between the end electrodes (2, 3); 4) forming a thermistor body; and forming an intermediate electrode (5) facing the end electrode (2, 3) on the thermistor body (4) formed across the end electrodes (2, 3). ), And an intermediate electrode cutting step of cutting a part of the intermediate electrode (5) on the thermistor body (4) so that the entire thermistor has a predetermined resistance value. A method for manufacturing a chip thermistor.

所定の大きさの絶縁基板（１）上の中央部に、中間電極（５）を形成する中間電極形成工程と、前記中間電極（５）に重なる一連のサーミスタ体（４）を形成するサーミスタ体形成工程と、前記サーミスタ体（４）の上に、前記中間電極（５）と対向する対を成す端部電極（２，３）を形成する端部電極形成工程と、サーミスタ全体が所定抵抗値と成るよう前記サーミスタ体（４）上の前記端部電極（２，３）の一部を切削する端部電極切削工程と、を備えることを特徴とするチップ型サーミスタの製造方法。An intermediate electrode forming step of forming an intermediate electrode (5) at a central portion on an insulating substrate (1) having a predetermined size, and a thermistor body forming a series of thermistor bodies (4) overlapping the intermediate electrode (5) A forming step, an end electrode forming step of forming a pair of end electrodes (2, 3) facing the intermediate electrode (5) on the thermistor body (4), and the entire thermistor having a predetermined resistance value An end electrode cutting step of cutting a part of the end electrodes (2, 3) on the thermistor body (4).