JPS60234864A - Thermal head - Google Patents

Abstract

PURPOSE:To ensure a moderate length of bonding wire while allowing uniformization of printing record density by varying the pattern width of an individual conductor by several stages in a conductor resistance correction area. CONSTITUTION:In an ''n'' area of individual conductors L1-Lm connected to resistors R1-Rm, when the individual conductors are formed with the pattern with less than that of those contacting heating resistors, the pattern width is varied by several staircases or monotonously in the single conductor so as to uniformize the conductor resistors of the individual conductors L1-Lm. That is, in a conductor resistance correction area ''n'', the smallest pattern width at the lower part is set at 0.04mm., a value which will not lower the yield in practice while the area ''W'' is provided with an intermediate pattern width at the upper part. For example, the pattern width of the area is set at 0.08mm. and in the discrete conductors contacting the resistance, the pattern width at 0.115mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head, and particularly to the shape of its conductor.

A conventional example will be described below with reference to the drawings.

FIG. 1 shows an example of a plan view of essential parts of a thermal head for a line printer. In the same figure, heating resistors R1 to Rm connected to a single driver IC are connected to conductors C, -C, . . . branched into strips from a common electrode C. A large number of individual conductors L1 to Lm are connected to the other end of the resistor, and these individual groove conductors are formed to extend to the bonding terminals T1 to Tm of the IC.An insulating layer is formed on the individual conductors. An IC indicated by a broken line is mounted through the bonding terminal.If desired, a terminal and a conductor for grounding the recording current are provided on the outside of the bonding terminal.This structure is the basic form and many arranged on a substrate are used as a line. This is a thermal head for printers.

Now, an A4-size thermal head having a total number of resistors of 1728 and a resolution of 8 resistors/rttpn will be explained as an example. If a single IC drives 32 resistors (m=32), then the IC is 4. A total of 54 pieces are arranged on the board at an own pitch. When m=64, a total of 27 ICs are arranged on the substrate at a pitch of 30 mm.

Here, m is 64, the width of each resistor R1 to Rm is 0.115 mm, and the gap between the resistors is 0.01++ m.
Then, the distance indicated by %Sa" is 7.99 mm.

Also, the distance indicated by (%b) is &0■, and the bond
The dimensions of the leading terminals T1 to Tm are preferably 0.5 m each. Therefore, if the gap between adjacent T1 and Tm is 0.1 m, the batten width of the individual conductors L1 to Lm in the area indicated by V"S" is calculated as follows: (7,9-0,5X2 )÷64#0.107 or less. That is, if the batten gap is 0.017, the batten width is approximately 0.09 m, and the width of the individual conductor in the area in contact with the resistor R1-m is approximately 78 mm, which is 0.115 mm. When bonding terminal Tp is TB and Tm is T64, in the narrow conductor width region "S", T32 and TBS are the longest and TI and T64 are the shortest, so L
The conductor resistance of 1tI164 is several ohms lower than the conductor resistance of I" 3! + L 33. For example, if the difference in conductor resistance is 50, then the resistance value of
000, 5 at rated operation with a power supply voltage of 12V.
The resistance deviation of Ω is 0. This becomes a power deviation of the OIW, and causes a periodic density deviation in the print recording density of the thermal head.

In other words, the print density recorded by the resistor connected to the portion corresponding to the terminals Tp and Tq of the 27 ICs is the lowest, and the print density recorded by the resistor connected to the portion corresponding to Ts=Tm is the lowest. Become the highest.

As a method to eliminate such drawbacks, for example, the patent application
8-185428, a method of equalizing the conductor resistance of the conductors L1 to Lm is generally used. That is, the first
As shown in the figure, on the IC mounting part side of the individual conductors L1 to Lm connected to the resistor parts 1 to 1m, a width smaller than the width of the button in contact with the resistor part (for example, 90, M5ms+ as cited) is attached. A conductor resistance correction area V″n″ is provided.
The width of the button in the area n'' is, for example, 0.09W in the above cited example.
It can be set as +. For example, this 1n" area is T1
In the case of the individual conductors Ll and Lm connected to Tm and Tm, the longest length is taken, and as it approaches Tp or Tq from Tl or Tm, the length is monotonically shortened, or if <L, Tp and Tq, the shortest length is taken. , individual conductors L1 to Lm
The conductor resistance deviation can be made uniform to 1Ω or less.

However, m=64. In other words, when a single IC drives 64 resistors, the dimension indicated by %Sn becomes long, which in turn increases the substrate width of the thermal head.For example, the width of the substrate between adjacent resistors increases. “Difference in dimension is 0.
3 tm, %% when m = 32, “dimension is 0
．． 3w + IX (32/2-1); it is about 4.5 wn, whereas the 1n" dimension in the case of m = 64 is 0.3 wn
X (64/2-1) ”: It has a large width of about 9.3ml11, and the width of the manufactured thermal head is essentially limited by the length of the conductor resistance correction area. In addition, in order to make the length of this correction region similar to the conventional one, 'X''n between adjacent resistors was
If the dimensional difference in " is reduced to half of the conventional one, the thermal head manufactured due to incomplete correction of the conductor resistance results in the above-mentioned periodic recording print density.

In order to eliminate these drawbacks, as the individual conductor moves from Tl to Tp section or from Tm to Tq section, as already filed by the same applicant as the present application on March 26, 1980, In other words, as the individual conductor approaches the center side of the mounted IC, the length of the bonding wire from the electrode on the IC to the bonding terminal on the board is gradually shortened, thereby reducing the length of the "n" conductor resistance correction region. A shortening method is also used for thermal heads.

That is, in FIG. 1, TI+T1 or Tm, Tm
-1 to T3. When the individual conductor moves to T, Tm-1, Tm-5, the distance of the latter individual conductor is 0.3
Since the conductor resistance is shortened to a certain extent, the conductor resistance is reduced, and therefore the total length n'' of the conductor resistance correction region is shortened.

However, in the thermal head using this method, the bonding wire length from the electrode on the IC to TI or Tmi is the longest, and the bonding wire length from Tp or Tq is the shortest.
Alternatively, it is inevitable that the bonding length up to Tm will be excessively longer than a practically allowable length.

In other words, if the width of the IC is 2rtas, the maximum bonding length when m=64 is (7,9-9-2)/2≠3
This makes the distance approximately 50 inches longer than the practically acceptable length of 2m+n. Long bonding wires come into contact with the end face of the mounted IC or short-circuit with the wiring on the substrate, reducing the yield of manufactured thermal heads. In order to eliminate this drawback, if the width of the individual conductor in the "S" region is made smaller, the conductor resistance correction region in the "n" region becomes longer and the substrate of the thermal head becomes wider.

Therefore, an object of the present invention is to provide a miniaturized thermal head that can make the length of the bonding wire that connects the electrodes of an IC and the terminals on the substrate to be appropriate, and can uniformly print and record once.

According to the present invention, in an individual conductor that is connected to a heating resistor, is formed to extend to a bonding terminal of an IC, and has a conductor resistance correction region having a batten width narrower than a portion in contact with the resistor, a conductor resistance The width of the button of the individual conductor in the correction region is varied in multiple steps, so that the width of the button is effectively widened for the individual conductor placed on the center side of the IC, and the width of the button is effectively widened for the individual conductor placed on the end face side of the IC. According to the present invention, a thermal head is obtained which is characterized in that the batten width is effectively narrowed.

Also, according to the present invention, it is connected to the heating resistor.

In an individual conductor formed with a narrow conductor width region disposed on the bottom surface of an IC via an insulating layer and extending to a bonding terminal of the IC, the button width of the individual conductor in the narrow conductor width region By varying the width in multiple steps, the width of the batten is effectively made wider for the individual conductors placed on the center side of the IC, and the width of the batten is effectively made narrower for the individual conductors placed on the edge side of the IC. It is also possible to obtain a thermal head characterized by the following.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 2 shows individual conductors L connected to resistors fL1 to Rm.
In the region of 1n'' from 1 to Lm, when forming the individual conductor to have a batten width narrower than the batten width of the individual conductor in contact with the heat generating resistor, the batten width is formed in a plurality of steps in a single individual conductor. In other words, within the conductor resistance correction region 1n'', the narrowest width at the bottom is determined by the manufacturing yield in practical terms. 0, 04+++n+, which is a value that does not reduce For example, it is set to 0.115W+, and in the longest distance individual conductor connected to Tp or Tq, the entire conductor width is effectively formed to reduce the conductor resistance and connected to L, Tt or Tm. Among the individual conductors having the shortest distance, C is one in which the conductor width is effectively narrowed while limiting the conductor width to the minimum dimension that does not reduce the yield, thereby increasing the conductor resistance. Therefore, the width dimension of the individual conductor i1 on the bottom surface of the IC v″d″
, 5×2 )=6.9wn Even if the length was lowered from about 3 wn, the length of the conductor resistance correction region ''n'' could be kept at the same level as the conventional one. As a result, the bonding wire length can be reduced to 2.5 van or less at most, and most bonding wires and wires have a length of 1 to 2 m, which is ideal for practical use.
The distance could be as follows.

Therefore, the thermal head of the present invention has a high manufacturing yield because it is manufactured with an appropriate length of bonding wire and the conductor width dimension is also set appropriately, and the thermal head has a high manufacturing yield. Since the conductor resistance is made uniform, it is compact and can provide uniform recording print density.

The effect of the present invention becomes significant when the conductor width is reduced to improve the recording resolution or when the film thickness of the individual conductor is reduced, or when the conductor resistance per unit length is increased.

Since the present invention exhibits the above effects, the material and film thickness of the individual conductor, the batten width, the number of steps for narrowing (widening) the batten width in the v′n" and "W" regions, or the method for narrowing (widening) (step change or monotonous change), the number of resistors that a single IC can drive.

Naturally, there are no restrictions on the resolution of the heat generating resistor, etc., and the application of the thermal head of the present invention is not particularly limited either, and it can naturally be used in line heads, serial heads, etc. Furthermore, the present invention brings the bonding terminal surface closer to the IC side one by one, and provides a conductor in an arbitrary shape in the gap created by the short bonding terminal for grounding the recording current flowing through the one heating resistor. You can also do it. Moreover, the present invention can be applied to the S" area with a narrow button width and to individual conductors on the lower surface of an IC mounting area.

In the present invention, for example, the area % having an intermediate batten width
It goes without saying that the formation of wII may start from a position that is the same size lower than the heating resistor box, and the widths of the tabs may be mutually different from L1 to Lm.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the main parts of a conventional example. FIG. 2 is a plan view showing essential parts of an embodiment of the present invention. C (C, ~Cm)... Common electrode, FL, ~R
m...Heating resistor, LL-Lm...Individual conductor s' Tl~Tm...Bonding terminal, S region...Narrow conductor width area, n area...conductor resistance correction area, W area...intermediate conductor width conductor resistance correction area. ht country 2nd flash

Claims (2)

[Claims] (1) In an individual conductor that is connected to a heating resistor and is formed to extend to a bonding terminal of an IC, and has a conductor resistance correction region whose button width is narrower than the part in contact with the resistor, the conductor resistance correction is performed. The width of the button of the individual conductor in the area is varied in multiple steps, so that the width of the button is effectively widened for the individual conductor placed in the center of the IC.
A thermal head characterized in that the batten width is formed to be effectively narrow in the individual conductors arranged on the end face side of the thermal head. (2) The individual conductor further includes a narrow conductor layer region disposed on the bottom surface of the IC via an insulating layer, and the batten width of the individual conductor in the narrow conductor width region is varied in multiple stages.
A patent characterized in that the individual conductors arranged on the center side of the IC have an effectively wide batten width, and the individual conductors arranged on the end face side of the IC have an effective batten width narrowed. A thermal head according to claim (1).