JPH02160560A - Thermosensitive head - Google Patents
Thermosensitive headInfo
- Publication number
- JPH02160560A JPH02160560A JP31389588A JP31389588A JPH02160560A JP H02160560 A JPH02160560 A JP H02160560A JP 31389588 A JP31389588 A JP 31389588A JP 31389588 A JP31389588 A JP 31389588A JP H02160560 A JPH02160560 A JP H02160560A
- Authority
- JP
- Japan
- Prior art keywords
- substrate
- conductor
- drive
- ceramic substrate
- wire
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 43
- 239000004020 conductor Substances 0.000 claims abstract description 27
- 239000000919 ceramic Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims description 12
- 239000011347 resin Substances 0.000 abstract description 2
- 229920005989 resin Polymers 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 230000002093 peripheral effect Effects 0.000 abstract 1
- 238000005476 soldering Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 10
- 230000007547 defect Effects 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Landscapes
- Electronic Switches (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、感熱ヘッドの構造に係り、特に、駆動ＩＣと
発熱抵抗体につながる導電体との接続部の信頼性が高く
、しかも、低コストの感熱ヘットに関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a thermal head, and in particular, the connection portion between the drive IC and the conductor connected to the heating resistor has high reliability and low heat resistance. Regarding the cost of thermal head.
従来の感熱ヘッドは、第２図に示すように、アルミナ、
炭化硅素等のセラミック基板２上に部分グレーズ、全面
グレーズ等が形成され、更に、薄膜状、あるいは、厚膜
状からなる発熱抵抗体１、及び、それにつづく導電体７
が基板２上に形成され、かつ、発熱抵抗体１を駆動する
ための駆動ＩＣ５をも基板２上に搭載した構造であった
。また、特開昭６２−２４４６６０号公報の感熱ヘッド
は、第３図に示すように、駆動ＩＣ５をセラミック基板
２上から除去してセラミック基板２の面積を小さくシ、
ガラスエポキシ基板のような安価な多層配線基板６（以
後、配線基板と称す）上に駆動ＩＣを搭載して、セラミ
ック基板２上に形成された発熱抵抗体につながる導電体
７と駆動ＩＣ５とをワイヤボンディング４により接続し
た構造である。Conventional thermal heads are made of alumina, as shown in Figure 2.
A partial glaze, a full glaze, etc. are formed on a ceramic substrate 2 made of silicon carbide, etc., and a heating resistor 1 in the form of a thin film or a thick film, and a conductor 7 following it.
was formed on the substrate 2, and a driving IC 5 for driving the heating resistor 1 was also mounted on the substrate 2. Furthermore, as shown in FIG. 3, the thermal head disclosed in Japanese Patent Application Laid-Open No. 62-244660 removes the drive IC 5 from the ceramic substrate 2 to reduce the area of the ceramic substrate 2.
A drive IC is mounted on an inexpensive multilayer wiring board 6 (hereinafter referred to as a wiring board) such as a glass epoxy board, and a conductor 7 connected to a heat generating resistor formed on a ceramic substrate 2 and a drive IC 5 are connected to each other. This structure is connected by wire bonding 4.
上記従来の感熱ヘッドでは、高価なセラミック基板の面
積が大きいため、感熱ヘッド自体も必然的に高価になら
ざるを得ないという欠点がある。The conventional thermal head described above has a drawback in that the expensive ceramic substrate has a large area, so the thermal head itself inevitably becomes expensive.
また、感熱ヘッドをより低コストとするために発熱抵抗
体につながる導電体の膜厚を薄くすると、第４図に示す
ように、ワイヤボンディング部の接合強度が低下してし
まう。更に、導電体の膜厚が薄い感熱ヘッドに、急熱急
冷を繰り返す温度サイクル試験を実施すると、５０サイ
クル目から不良が発生してしまうという問題がある。こ
れは、導電体の膜厚が厚い場合は、基板の影響をあまり
受けないので、ボンディングの際、ワイヤだけではなく
導電体の瞑の変形も起こり易く、ワイヤがそれほど変形
しなくとも十分な接合が生じるが、導電体の膜厚が薄く
なると硬いセラミック基板の影響が大きいため、ワイヤ
の変形のみが促進され、接合部の肉厚が薄くなりすぎる
ことが原因である。Furthermore, if the thickness of the conductor connected to the heating resistor is made thinner in order to lower the cost of the thermal head, the bonding strength of the wire bonding portion will be reduced, as shown in FIG. Furthermore, when a thermal head having a thin conductor film is subjected to a temperature cycle test in which rapid heating and cooling are repeated, there is a problem in that defects occur from the 50th cycle onwards. This is because when the conductor film is thick, it is not affected much by the substrate, so during bonding, not only the wire but also the conductor is likely to be deformed, and even if the wire does not deform much, sufficient bonding can be achieved. However, as the thickness of the conductor becomes thinner, the influence of the hard ceramic substrate becomes greater, so only the deformation of the wire is accelerated, and the reason is that the thickness of the joint becomes too thin.
また、特開昭６２−２４４６６０号公報に記載の感熱ヘ
ッドでは、駆動ＩＣを安価な配線基板に搭載しているの
で、従来の感熱ヘッドに比べ、低コストであるが、セラ
ミック基板と配線基板の分離部をワイヤボンディングで
接続しているため、熱応力等がボンディング部に集中し
、ワイヤの破断が起こるという問題もある。In addition, the thermal head described in JP-A No. 62-244660 has a drive IC mounted on an inexpensive wiring board, so the cost is lower than that of conventional thermal heads. Since the separated portions are connected by wire bonding, there is also the problem that thermal stress and the like concentrate on the bonding portions, causing the wires to break.
また、セラミック基板上に導電体を形成するには、金属
ペーストを塗布後、焼成を行う方法やスパッタ法により
膜の形成を行う方法があるが、前者では、膜厚が不均一
であったり、焼成時に炉壁の異物が混入しやすく、後者
では、１０μｍ程度の厚膜を形成するには時間がかかり
すぎるという欠点がある。In addition, to form a conductor on a ceramic substrate, there are two methods: applying a metal paste and then firing it, and forming a film by sputtering. However, in the former method, the film thickness may be uneven, Foreign matter from the furnace wall tends to get mixed in during firing, and the latter has the disadvantage that it takes too much time to form a thick film of about 10 μm.
上記目的は、発熱抵抗体周辺のみをセラミック基板上に
形成することにより、セラミック基板の面積を小さくし
、かつ、発熱抵抗体につながる導電体と駆動ｒｃとの接
続は、駆動ＩＣが搭載されている配線基板上でワイヤボ
ンディングを行うことにより達成される。The above purpose is to reduce the area of the ceramic substrate by forming only the area around the heat generating resistor on the ceramic substrate, and to connect the conductor connected to the heat generating resistor and the drive RC with the drive IC mounted. This is achieved by wire bonding on the existing wiring board.
駆動ＩＣを搭載する配線基板は、例えばガラスエポキシ
基板のような多層プリント板であるので、セラミック基
板と比較すると、安価であり、基板硬さもそれ程、硬く
はない。The wiring board on which the drive IC is mounted is a multilayer printed board, such as a glass epoxy board, so it is less expensive and less hard than a ceramic board.
また、配線である導電体は、めっき法により形成するこ
とができるので、均一な膜厚を得ることができ、しかも
、１０μｍ程度の厚膜も比較的容易に形成することがで
きる。Further, since the conductor, which is the wiring, can be formed by a plating method, a uniform film thickness can be obtained, and a film as thick as about 10 μm can be formed relatively easily.
これにより、ボンディングの際、基板の影響を受け、ワ
イヤの変形のみが促進されて接合部の肉厚が薄くなりす
ぎることはなくなるので、ワイヤがそれほど変形しなく
とも、膜と十分な接合を得ることができるため、高い接
合強度が得られる。As a result, during bonding, only the deformation of the wire is promoted due to the influence of the substrate, and the wall thickness of the bonded part does not become too thin. Therefore, sufficient bonding with the film can be achieved even if the wire does not deform much. As a result, high bonding strength can be obtained.
さらに、発熱抵抗体につながる導電体と駆動ＩＣの接続
は、駆動ＩＣが搭載されている配線基板上で行うので、
熱応力等がワイヤボンディング部に集中することもない
ため、ワイヤ破断が起こるという問題も解決される。Furthermore, since the connection between the conductor connected to the heating resistor and the drive IC is made on the wiring board on which the drive IC is mounted,
Since thermal stress and the like are not concentrated on the wire bonding portion, the problem of wire breakage is also solved.
以下１本発明の一実施例を第１図により説明する。 An embodiment of the present invention will be described below with reference to FIG.
第１図は、発熱抵抗体周辺のみをセラミック基板上に形
成した感熱ヘッドの断面図である。FIG. 1 is a sectional view of a thermal head in which only the periphery of a heating resistor is formed on a ceramic substrate.
発熱抵抗体１が形成されたセラミック基板２と駆動ＩＣ
５を搭載した配線基板６は放熱板３上に隣接して固定さ
れている。発熱抵抗体につながる導電体７は配線基板６
上までつづいており、この基板上で、駆動ＩＣ５とボン
ディングワイヤ４によって電気的に接続されている。こ
のように、配線基板上でワイヤボンディングを行った際
の接合強度は第６図に示すように、セラミック基板上の
それと比べてはるかに高い。Ceramic substrate 2 on which heating resistor 1 is formed and drive IC
A wiring board 6 on which a wiring board 5 is mounted is fixed adjacent to the heat sink 3. The conductor 7 connected to the heating resistor is the wiring board 6
It continues to the top and is electrically connected to the drive IC 5 by bonding wires 4 on this board. As shown in FIG. 6, the bonding strength when wire bonding is performed on a wiring board is much higher than that on a ceramic substrate.
また、急熱急冷を繰り返し行う温度サイクル試験でも、
２００〜終了後も不良は発生しない。In addition, in a temperature cycle test in which rapid heating and cooling are repeated,
No defects occur even after 200~.
次に、セラミック基板２と配線基板６の電気的接続方法
を第７図ないし第９図で詳述する。Next, a method for electrically connecting the ceramic substrate 2 and the wiring board 6 will be described in detail with reference to FIGS. 7 to 9.
第７図は、発熱抵抗体周辺のみをセラミック基板上に形
成した感熱ヘッドの平面図である。発熱抵抗体につなが
る導電体７は幅１００μｍ程度の配線であり、配線基板
６上で駆動ＩＣ５とボンディングワイヤ４で接続されて
いる。FIG. 7 is a plan view of a thermal head in which only the periphery of the heating resistor is formed on a ceramic substrate. The conductor 7 connected to the heat generating resistor is a wiring having a width of about 100 μm, and is connected to the drive IC 5 on the wiring board 6 by a bonding wire 4.
第８図、第９図は、セラミック基板２と配線基板６の接
続部の断面図である。二つの基板の電気的な接続法には
、第８図に示すように、基板の側面まで導電体を形成し
、互いに接着する方法や、第９図に示すように、各々の
基板に導電体を形成後、二つの基板を接着し、導電体間
を半田ペースト８のような導電性樹脂等により接続する
方法などがある。これらの方法は、従来より公知の方法
であり、容易に行うことができる。8 and 9 are cross-sectional views of the connection portion between the ceramic substrate 2 and the wiring board 6. FIG. There are two methods for electrically connecting two substrates: as shown in Figure 8, conductors are formed up to the sides of the substrates and then bonded to each other, and as shown in Figure 9, conductors are formed on each substrate. After forming the two substrates, there is a method of bonding the two substrates and connecting the conductors with a conductive resin such as solder paste 8. These methods are conventionally known methods and can be easily performed.
本発明によれば、ボンディングの際、ワイヤがそれほど
変形しなくても、すなわち、接合部のワイヤの肉厚が厚
い状態でも、十分な接合が可能であるので、ワイヤボン
ディングの接合部の信頼度が高くなる。According to the present invention, sufficient bonding is possible even if the wire does not deform much during bonding, that is, even if the wire at the bonding portion is thick, the reliability of the wire bonding bond is increased. becomes higher.
第１図は本発明の一実施例の感熱ヘッドの断面図、第２
図、第３図は従来の感熱ヘッドの断面図、第４図は、セ
ラミック基板上の導電体の膜厚と接合強度の関係を示す
グラフ、第５図は温度サイクル試験の回数とセラミック
基板上のワイヤボンディング部の不良数との関係を示す
グラフ、第６図は配線基板上、及び、セラミック基板上
のワイヤボンディング部の接合強度を示すグラフ、第７
図は第１図の平面図、第８図、第９図はセラミック基板
と配線基板の接合部の晴面図である。
１・・・発熱抵抗体、２・・・セラミック基板、３・・
・放熱板、４・・・ボンディングワイヤ、５・・駆動Ｉ
Ｃ，６・・・配線基板、７・・・導電体、８・・・半田
ペースト。
第 １０
第４０
４９ｆ、、繰六Ｅ、（ｅη・ン
第９図
第３図FIG. 1 is a sectional view of a thermal head according to an embodiment of the present invention, and FIG.
Fig. 3 is a cross-sectional view of a conventional thermal head, Fig. 4 is a graph showing the relationship between the film thickness of the conductor on the ceramic substrate and the bonding strength, and Fig. 5 is a graph showing the relationship between the number of temperature cycle tests and the bonding strength on the ceramic substrate. Figure 6 is a graph showing the relationship between the number of defective wire bonding parts and the number of defects in wire bonding parts on wiring boards and ceramic substrates.
The figure is a plan view of FIG. 1, and FIGS. 8 and 9 are clear views of the joint portion between the ceramic substrate and the wiring board. 1... Heat generating resistor, 2... Ceramic substrate, 3...
- Heat sink, 4... Bonding wire, 5... Drive I
C, 6... Wiring board, 7... Conductor, 8... Solder paste. 10th 40th 49f,, 6E, (eη・n Fig. 9 Fig. 3
Claims (1)
抵抗体を駆動するための駆動ＩＣを搭載している配線基
板と放熱板とからなる感熱ヘッドにおいて、 前記発熱抵抗体列につながる導電体と前記駆動ＩＣとの
接続は、前記配線基板上で行うことを特徴とする感熱ヘ
ッド。 ２、特許請求項第１項に記載の感熱ヘッドにおいて、 前記発熱抵抗体列につながる前記導電体と前記駆動ＩＣ
との接続は、ワイヤボンディング法により行われること
を特徴とする感熱ヘッド。[Scope of Claims] 1. A thermal head comprising a ceramic substrate provided with a row of heat generating resistors, a wiring board and a heat sink on which a driving IC for driving the heat generating resistors is mounted, and the heat generating resistors: A thermal head characterized in that the conductor connected to the body array and the drive IC are connected on the wiring board. 2. In the thermal head according to claim 1, the conductor connected to the heating resistor array and the drive IC
A thermal head characterized in that connection to the head is made by a wire bonding method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31389588A JPH02160560A (en) | 1988-12-14 | 1988-12-14 | Thermosensitive head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31389588A JPH02160560A (en) | 1988-12-14 | 1988-12-14 | Thermosensitive head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02160560A true JPH02160560A (en) | 1990-06-20 |
Family
ID=18046804
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31389588A Pending JPH02160560A (en) | 1988-12-14 | 1988-12-14 | Thermosensitive head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02160560A (en) |
-
1988
- 1988-12-14 JP JP31389588A patent/JPH02160560A/en active Pending
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