JPH0557941A - Thermal head and driving ic therefor - Google Patents

Abstract

PURPOSE:To simplify manufacturing process by arranging common electrode patterns on an IC chip side and in the opposite direction thereto through a heat generating resistor, connecting the patterns by N patterns, and arranging a driving terminal of the heat generating resistor on the side of the heat generating resistor of the IC chip. CONSTITUTION:Glass paste is printed on an alumina ceramic, dried, and baked so as to form a heat accumulating layer 2 on an alumina ceramic substrate 1. Next, a predetermined conductive pattern 3 is formed on the heat accumulating layer 2 by photomechanical process and etching. Also, a heat generating resistor 4 having a shape of continuous band is formed on the conductive pattern 3. The top surface of it is covered with a glass layer 5 as a protective layer so as to obtain a heat generating substrate 6. In the conductive pattern 3, an end common electrode 24a is provided placed on a discharging side of printing papers and connected to the heat generating resistor 4, and an IC lower common electrode 24b is arranged on a lower part of the mounting position of an IC chip 8. The common electrodes 24a and 24b are connected by a common electrode connecting pattern 27 and an individual electrode 25 is connected to the heat generating resistor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved thermal head.

[0002]

2. Description of the Related Art FIG. 21 is for example from Mitsubishi Electric Corporation 1990.
FIG. 22 is a partial perspective view of an F series thermal head published in April, FIG. 22 is a sectional view thereof, and FIG. 23 is an equivalent circuit diagram thereof. 21, 22, and 23, 1 is an alumina ceramic substrate, 2 is a heat storage layer, 3 is a conductor pattern, 4
Is a heating resistor, 5 is a protective film, 6 is a heating substrate, 7 is an adhesive, 8 is an IC chip, 9 is a gold wire, 10 is a printed circuit board, 11 is a backside solder resist, 12 is a backside pattern, 13
Is a surface pattern, 14 is a surface solder resist layer, 15 is a bonding terminal, 16 is a connector, 17 is solder, 18 is a support, 19 is double-sided tape, 20 is recording paper, 21 is platen roller, 22 is protective resin, 23 Is a cover, 57 is a pattern in which the common electrode is routed (hereinafter referred to as PCOM), 63 is a pattern in which the ground terminal is routed (hereinafter referred to as PGND), and 80
A circuit 90 of the IC chip 8 (hereinafter referred to as an IC circuit) 90 is a common reinforced portion formed to reduce the wiring pattern resistance of the common electrode pattern PCOM63.

FIG. 24 shows an IC of a conventional thermal head.
It is a chip mounting diagram, 34 is a probe terminal, 37, 38, 41,
42, 43, 44, 45, 46, 47a, 47b, 47c are IC chips 8
DATA IN, DATA OUT respectively
, CLOCK, VDD, ENH, ENL, GND-
L, LATCH, GND-H, and 48, 49, 5
0, 51, 52, 53, 54 are bonding terminals of the printed circuit board 10.
BC connected to each signal of the IC chip 8 at 15
LOCK, BVDD, BENH, BENL, BGND-
L, BLATCH, BGND-H, 100 is DAT
B DATA IN connected to A IN38, 101 is DA
BDATA OUT is connected to TA OUT 37, and 100 and 101 are sequentially pattern-connected on the printed circuit board 10 side. The BDATA IN100 extends to the end of the printed circuit board 10 because it also serves as a plating lead when the printed circuit board 10 is manufactured. Further, in the conventional thermal head, the adhesive protruding from the adhesive of the IC chip diffuses along the edge of the protective film 5, and the conductor pattern cannot be connected to the Au wire 9 due to the capillary phenomenon, or the Au wire 9 cannot be connected. However, poor connection such as weak strength occurred.

[0004]

Since the conventional thermal head is constructed as described above, there is a defect in wire bonding to the wire bonding terminal of the printed circuit board, or a common strengthening process is required.
Since the probe terminal is located on the recording paper discharge side, the thermal paper may have accumulated debris, leading to defective printing and impairing the reliability of the pattern. Further, there is a problem that the loss difference in the IC chip is large and the print quality is deteriorated. Also ENH, EN
When the L signal is not required, the pattern of the printed circuit board has to be changed considerably and the wiring becomes complicated. The present invention has been made to solve the above problems, and an object thereof is to simplify the process of manufacturing a thermal head, improve yield, improve reliability, improve print quality, and simplify the layout of conductor patterns. And

[0005]

In order to achieve the above object, in the thermal head of the present invention, a common electrode pattern is arranged on the IC chip side and in the opposite direction through a heating resistor, The common electrode pattern is connected in a plurality of patterns, the drive terminal of the heating resistor is arranged on the heating resistor side of the IC chip, and is connected to the conductor pattern.
This is effective when the heating resistor is a strip-shaped continuous resistor. Further, a probing point of a common electrode is provided between the heating resistor and the IC chip, or a high conductive film is brought into contact with such a probing point. IC
The width of the insulating pattern between the chip and the common electrode pattern may be partially changed. On the other hand, through the heating resistor,
A common electrode pattern is arranged on the IC chip side and in the opposite direction, the common electrode patterns are connected by N patterns, and the external common electrode pattern connected to the IC chip side common electrode pattern is the external common electrode. The connection connector was connected in a pattern substantially orthogonal to the pattern. Further, the print data input terminal and the print data output terminal are arranged on the heat generating resistor side of the IC chip, or the drive terminals of the heat generating resistor of the IC chip consist of a group of several arranged at the same pitch, The common electrode connection pattern is arranged so as to be located between the groups. Furthermore, it is preferable to arrange such groups at the same pitch of M at the end and 2M at the center. A common electrode may be arranged below the IC chip, or a drive signal terminal of the IC chip may be connected to a conductor pattern on another substrate, and a wide conductor pattern may be arranged below the connected conductor pattern position. The wide conductor pattern of another substrate may be a common electrode pattern connected to the common electrode pattern on the insulating substrate. It is also preferable that the conductor pattern to which the drive signal terminal of the IC chip on another substrate is connected does not extend to the substrate end on the IC chip side. A heating resistor drive terminal, a print data input terminal, and a print data output terminal are arranged on one side in the longitudinal direction of the IC chip, a ground terminal is arranged near the central portion, and an IC chip drive signal terminal is arranged on the other side. I
The driving terminals of the heating resistors of the C chip are M and 2M groups arranged at the same pitch, and the interval between the groups is changed to the arrangement pitch of the driving terminals, and the data input terminal and the data are provided at the end of the IC chip. Output terminals are arranged. There are three ground terminals, one of which is located at the center of the drive terminals of the L heating resistors, and the other two are located at a location separated from the center drive terminal by L / 4 to 2L / 5 terminals. did. An IC chip driving power supply terminal is adjacent to a signal terminal connected to a pull-down resistor inside the IC chip of the IC chip driving signal terminal, and an IC is adjacent to a signal terminal connected to a pull-up resistor inside the IC chip. Used as the ground side terminal of the chip drive power supply. A rectangular pattern for pattern recognition was provided on the connection terminal portion of another substrate connected to the drive signal terminal of the IC chip. The number of connection points between the drive signal terminal of the IC chip and the conductor pattern is two or more. The width of the common electrode pattern is made wider than the width of the individual electrode in the comb-shaped portion where the common electrode and the individual electrode alternate.

[0006]

In the thermal head according to the present invention, it is not necessary to fold all the common electrode patterns back. When the heating resistor has a strip shape, the heat of the heating resistor is transferred to the adjacent element. By providing the probing point at the above position, probing can be performed for each block, and dust on the thermal paper does not accumulate. Moreover, static electricity is conducted to the probing point by bringing the high conductive film into contact. As described above, the insulating pattern in which the pattern width is partially different prevents the capillary action of the adhesive agent. With the above configuration, the common electrode pattern can be routed from one side. By arranging the data input terminal, data output terminal, and drive terminal in the IC chip in one direction, and connecting them to the conductor pattern on the insulating board, it does not become a plating lead, and the print data input / output terminal is arranged on the heat generating board. By doing so, disconnection due to the difference in coefficient of thermal expansion between the heat generating substrate and the printed wiring board is prevented. By arranging the drive terminal arrangement in the IC chip into groups and arranging the common electrode connection pattern between the groups, the gold wire does not come into contact with the connection pattern. The drive terminals have the same pitch by forming M groups at the ends and 2M groups at the center. By disposing the common electrode under the IC chip, it is possible to effectively use the area of the heat generating substrate. By connecting the drive signal terminal of the IC chip to a conductor pattern on another substrate and disposing a wide conductor pattern below the connected conductor pattern position, the bottom of the wire stitch portion of the printed wiring board becomes flat. The common electrode pattern is facilitated by using the wide conductor pattern of another substrate as the common electrode pattern connected to the common electrode pattern on the insulating substrate. Since the conductor pattern to which the drive signal terminal of the IC chip on another substrate is connected does not reach the end of the substrate on the IC chip side, the plating lead of the printed circuit board becomes unnecessary. By arranging the heating resistor drive terminal, print data input terminal and print data output terminal on one side in the longitudinal direction of the IC chip, arranging the ground terminal near the center and arranging the IC chip drive signal terminal on the other side. , The pattern arrangement of the IC chip becomes easy, and the GND pattern can be widened in the center.
The driving terminals of the heat generating resistors of the IC chip are M and 2M groups arranged at the same pitch, and the intervals between the groups are different from the driving terminal array pitch, so that the driving terminals have the same pitch.
There are three ground terminals, one of which is located at the center of the drive terminals of the L heating resistors, and the other two are located at a location separated from the center drive terminal by L / 4 to 2L / 5 terminals. Then, the variation in loss voltage between bits is reduced. I
The IC chip drive power supply terminal is adjacent to the signal terminal connected to the pull-down resistor inside the IC chip of the C-chip driving signal terminal, and the IC terminal is adjacent to the signal terminal connected to the pull-up resistor inside the IC chip. The pattern can be shared by using the ground side terminal of the chip drive power supply. Since the rectangular pattern is provided on the terminal serving as the connection pattern of the separate board, the recognition rate in pattern recognition is increased. Since the separate substrate and the IC chip drive signal terminal are connected at two or more points, even if one of them is disconnected, it becomes a fail safe. By making the common electrode pattern width wider than the width of the individual electrode in the comb-shaped part where the common electrode and the individual electrode alternate, the loss of the common electrode connection pattern is reduced when the resistance value of the heating resistor is low and the current is large. be able to.

[0007]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial perspective view of a thermal head showing this embodiment, and FIG. 2 is a sectional view thereof. In FIGS. 1 and 2, 1 is an alumina ceramic substrate having an alumina purity of 96%, 2 is a glass layer formed by coating the alumina ceramic substrate 1, for example, to improve the base of the alumina ceramic substrate 1 and the thermal response of a thermal head. It affects the characteristics (hereinafter referred to as the heat storage layer). 3 is a conductor pattern patterned on the heat storage layer 2, 4 is a continuous strip-shaped heating resistor made of, for example, ruthenium oxide, etc. formed on the conductor pattern 3, and 5 is a resistance that covers the heating resistor 4. A glass layer serving as a wear and protection layer (hereinafter referred to as a protection film) also serves as an insulating layer covering a part of the conductor pattern 3. Reference numeral 6 denotes a substrate on which these heating resistors 4 are formed (hereinafter referred to as a heating substrate).
Reference numeral 7 denotes an adhesive agent applied on the heat-generating substrate 6, for example, an epoxy resin, and 8 is an IC chip having a function of selectively driving the heat-generating resistor 4 based on print information. It is fixed to. Reference numeral 9 is, for example, a gold wire that connects the conductor pattern 3 individually connected to the heating resistor 4 and the operation signal of the IC chip 8, and 10 is another board (hereinafter referred to as a printed circuit board) for routing the operation signal of the IC chip 8. The back surface side is a back surface solder resist layer 11 and a back surface pattern 12 which are insulating layers, and the front surface side is a surface pattern 13 and a surface solder resist layer which is an insulating layer covering the surface pattern 14. And the back surface pattern 12 are connected by a through hole (not shown). Further, a part of the surface pattern 13 is plated with gold to form a bonding terminal 15 which is connected to the IC chip 8 and the gold wire 9. Reference numeral 16 denotes a connector fixed to the printed circuit board 10 with solder 17, which is a connection point of the thermal head drive signal cable. Reference numeral 18 denotes a support base that adheres and supports the heat generating substrate 6 and the printed circuit board 10 with, for example, double-sided tape 19, for example, a support base made of aluminum, iron, polycarbonate or the like, 20 is recording paper such as thermal paper or transfer paper, and 21 is recording. A platen roller for transporting paper, which is positioned on the protective film 5 on the heating resistor 4 and rotates. Reference numeral 22 is a protective resin that protects the IC chip 8 and the gold wire 9, such as a silicone resin, and 23 is a cover that is also a resin such as polycarbonate that also serves as an external pressure-preventing recording paper 20 conveyance guide. 18
It is fixed on.

FIGS. 3 to 7 show a process of mounting the IC chip 8 on the heat generating substrate 6 and connecting the conductor pattern 3 to the gold wire 9. FIG. It is shown using the figure, and it shows that it is manufactured in the direction of the arrow. Here, for example, a glass paste in which a trace amount of strontium is mixed on an alumina ceramic having an alumina purity of 96% is printed to a thickness of about 70 μm, dried, and then placed in a firing furnace at 1200 ° C to 1300 ° C, and then cooled to an alumina ceramic substrate. The heat storage layer 2 is formed on the heat storage layer 1, and the surface roughness of the heat storage layer is made more uniform by mixing a small amount of strontium. Next, an organic gold paste is printed, dried, and baked on the entire surface of the heat storage layer 2 to form a conductor layer 300 of gold having a thickness of about 0.5 μm, a photosensitive resist is applied on the conductor layer 300, and photoengraving is performed. Then, the necessary conductor pattern 3 is formed by the etching technique. The thickness of the gold pattern of the conductor layer 300 is preferably as thick as possible in view of the wire bond strength of the gold wire 9, but it is necessary to minimize the amount of expensive gold, which is a precious metal, used. From the experiments and results, the wire bond strength began to drop extremely below 0.5 μm. The surface roughness of the heat storage layer 2 is 0.
When it was about 1 μmp-p or more, the capillaries did not evenly hit the conductor pattern during wire bonding, and the yield of wire bonding began to deteriorate.

FIG. 4 shows the arrangement of the conductor pattern 3 on the heat generating substrate 6. In FIG. 4, reference numeral 24a denotes an end common electrode located on the discharge side of the recording paper 21 and the heating resistor 4
Connected to. Further, as the distance from the heating resistor 4 is shorter, the thermal head can be downsized, and the recording by selectively driving the heating resistor 4 on the recording paper 20 can be seen immediately. 24b is an IC lower common electrode arranged below the mounting position of the IC chip 8, 25 is an individual electrode connected to the heating resistor 4, 26a and 26b are individual electrode groups a in which several individual electrodes are grouped, In the electrode group b shown in FIG. 4, the individual electrode group a26a corresponds to the individual electrode 254 and the individual electrode group b26b corresponds to the individual electrode 258. In addition, the individual electrode group a26a and the individual electrode group b26b are the end common electrode 24a,
It is partitioned by a common electrode connection pattern 27 that connects to the IC lower common electrode 24b. 28 is a terminal for connecting a print data input signal to the IC chip 8; a DIN terminal; 29 is a terminal for connecting a print data output signal from the IC chip 9; and a DOUT terminal, which is a DIN terminal 28. The DOUT terminal 29 is pattern-connected on the heating substrate. 30 is I
A recognition pattern for automatic recognition of the wire bonding of the C chip 8, 31 is a position recognition pattern indicating the position of the IC chip 8, 32 is a common electrode block terminal, 33 is an individual electrode 25, and a common electrode 24 pattern is arranged alternately. On the comb-shaped portion 33, for example, a resistive paste containing ruthenium oxide, a glass component, zirconia, etc., is directly drawn in a strip shape using a dispenser, dried and fired to form a plurality of heating resistors 4. Formation is made. The comb-shaped part shown in FIG.
The heating resistor is formed on the 33. Here, the direct drawing of the resistance paste is carried out by a device such that the positions are calculated by the automatic recognition of the recognition patterns 30, 31, etc., and they are accurately positioned on the comb-shaped portion 33. Individual electrode 25 of comb 33
In the case of a thermal head having a resolution of 8 dots per 1 mm and the pattern width of the common electrode 24a and the pattern interval, for example, the pattern width is 30 μm, the pattern interval is 32.5 μm, the length of the alternating comb portion is 0.6 mm, and the heating resistor 4 is used. Is formed with a width of 0.22 mm. When the resistive paste is applied by the printing method, the mesh shape of the printing screen causes the width of the heating resistor 4 to vary, and the strip-shaped resistor width is about 0.18 to 0.26 mm with respect to the center value of 0.22 mm. The heat generation temperature of the heat generating resistor 4 is different between the narrow portion and the wide portion of the resistor due to variations in the mesh shape, which causes uneven recording on the recording paper and leads to deterioration of print quality. In the direct drawing method, the width of the resistor and the thickness of the resistor can be made uniform by changing the drawing speed and the resistance paste application pressure by recognizing the pattern of the application position and the application shape. .. After the heating resistor 4 is formed, on the heating resistor 4,
A glass paste is screen-printed on the lower part of the IC chip 8 and dried and baked to form the insulating protective film 5. FIG. 6 shows the arrangement of the protective film 5, and the portions not covered by the protective film 5 are the common electrode connection pattern 27 and the DIN terminal.
28, DOUT terminal 29, recognition pattern 30, common electrode block terminal 32 part of probe terminal 34, individual electrode terminal 35,
It becomes the part of the common connection terminal 36. Here, the heating resistor 4
Is 1500Ω, the loss resistance of the common electrode lead is approximately 5Ω, M = 2048, N = 512 (where M is the number of heating resistors and N is the number of common electrode connection patterns).
Then, the loss per lead of the common electrode is about 0.3v, but since the common electrode is arranged, the loss is alleviated, and since it is a strip-shaped continuous resistor, heat is applied to the adjacent heating resistor. There is conduction and the image quality is not affected.

Now, the test items for manufacturing the heat generating substrate 6 are as follows.
This is to check the pattern shapes of the conductor pattern 3 and the protective film 5 and to measure the resistance value of the heating resistor that affects the performance of the thermal head. Further, in a thermal head using a ruthenium oxide type resistor, pulse trimming of the resistance value is also performed. Here, the measurement of the resistance value and the pulse trimming are performed by applying a pulse voltage to the probe terminal 34 serving as the terminal of the common electrode and the individual electrode terminal 35 with a probe having a needle-shaped tip. With an A4 size thermal head with a resolution of 8 dots per mm, the number of individual electrode terminals 35 is 1728, and the total length is 1728 x 1/8 = 21.
It will be 6 mm. Here, it is quite difficult to make 1728 needle-shaped probes with a pitch of 0.125 mm at 216 mm, and probing 1728 terminals at the same time is quite difficult considering the flatness of the heat generating substrate. is there. Due to the above-mentioned difficulties, at present, it is carried out by using a device that moves 64 times every 8 mm by using a probe with 64 individual electrode terminals 35 and a common electrode terminal. Since the position of the probe terminal 34 of the common electrode of the conventional thermal head is on the discharge side of the recording paper 20, the thermal paper of the recording paper 20 has accumulated debris, which may cause defective printing or adversely affect the conductor pattern. Since 34 is positioned in the feeding direction of the recording paper 20 so as not to touch the recording paper 20, the above problem does not occur. Also,
Since it is located at both ends of the IC as shown in the figure,
It can also be used as a mark for pattern recognition.

FIG. 7 shows a state in which the IC chip 8 is mounted on the heat generating substrate 6. Adjacent positions of the individual electrode terminals 35 are arranged in a staggered manner, and the gold wire 9 connection positions on the IC chip 8 side are arranged in a line. Here, the circuit diagram of the IC chip 8 is shown in FIG. 8 and has a 64-bit driver structure with a shift register latch. The print information of one line is synchronized with the CLOCK signal from the DATA terminal,
It is placed in a 64-bit shift register circuit. Next, the print information is transferred to the 64-bit latch circuit serving as a memory circuit at the timing of inputting the LATCH signal. Only when the ENL signal is LOW and the ENH signal is HIGH in the bit corresponding to HIGH in the print information of the latch circuit, DO1 is set.
~ DO64 is selectively switched. This DO1
By connecting the heating resistor 4 to the DO64,
Can be selectively driven based on the print information. In FIG. 8, VDD is a drive power supply terminal of the IC chip 8, GND-L is a circuit power supply ground terminal, GND-H is a grounding terminal of a switching element, DATA OUT is a data output terminal from a shift register, and an IC chip of the next stage. 8 DATA IN terminal. In a thermal head of A4 size and having a resolution of 8 dots per mm, there are 1728 heating resistors 4 and 27 64-bit IC chips 8 are mounted on the heating substrate 6 and connected. In this embodiment, the length of the IC chip 8 is 7.25 mm, and DO1 to DO4, DO
5 to DO12, DO13 to DO20, DO21 to DO28,
DO29 to DO36, DO37 to DO44, DO45 to DO
52, DO53 to DO60, DO61 to DO64 pitch 0.
At 105 mm, DO4 and DO5, DO12 and DO13, DO20 and DO21, DO28 and DO29, DO36 and DO37, DO44 and D
Distance between O45, DO52 and DO53, DO60 and DO61 (hereinafter,
The COM interval 40) is 0.12 mm. Then, the common electrode connection pattern 27 is positioned at the COM interval 40 position. DO1 to DO4 and DO60 to DO64 correspond to the individual electrode group a26a, and the other DO bits correspond to the individual electrode group b26b. Here, as for the size of the individual electrode terminal 35, if the diameter of the gold wire 9 is 25 μm, it is crushed to 90 μm or more when bonded to the individual electrode terminal 35 with a capillary at the time of wire bonding and the gold wire 8 and the individual electrode terminal
35 will be connected. Therefore, the individual electrode terminals 35 are arranged in a staggered arrangement so as not to contact the adjacent individual electrode terminals 36 even if this squeeze out occurs. Further, since the COM interval 40 is expanded and the common electrode connection pattern 27 is aligned,
This prevents contact with the common electrode connection pattern 27 due to the sagging of the gold wire 9. Further, the common electrode connection pattern 27 may be covered with the protective film 5, but it is difficult because the interval is only 0.12 mm. The accuracy of screen printing is ± 0.2 in terms of position accuracy.
mm, screen pattern accuracy is ± 0.05 mm, width variation due to screen mesh, bleeding of glass paste, and other problems are presently difficult.

DATA IN38 of the IC chip 8 is DIN
The DATA OUT 37 is connected to the terminal 29, the DOUT terminal 28 is connected to the DOUT terminal 28 by the gold wire 9, and the IC chip 8 is sequentially connected to data. Of course, the wire bonding of these gold wires 9 is performed accurately by performing the pattern recognition of the recognition pattern 30 and the position recognition pattern 31, while the printed board 10 and the IC chip 8 are shown in FIGS. 9 and 11. It shows an arrangement and a pattern for connecting the heat generating substrate 6 with a gold wire 9. In FIG. 9, the IC chip 8
In the above, 41 is CLOCK, 42 is VDD, 43 is ENH, 44 is ENL, 45 is GND-L, 46 is LATCH, 47 is GND.
There are three places at -H, 47a, 47b, and 47c. Further, 15 is a wire bonding terminal of the printed circuit board 10, which is a surface pattern 13
For example, 5-10 nickel on copper with a thickness of 15-30 μm
It is a portion of about .mu.m thick, and nickel is electrolytically plated with gold plating of about 0.5 .mu.m thick. Although gold can be directly plated on copper, since wire bonding is performed by heating, copper and gold are diffused, which leads to defective wire bonding and oxidation of copper. Therefore,
The nickel layer is interposed about 10 μm thick. Reference numeral 14 is a surface solder resist layer that covers the copper pattern of the surface pattern 13 and the substrate. 48 to 55 are signal terminals of the bonding terminal 15, 48 is BCLOCK connected to CLOCK41 of the IC chip 8 by the gold wire 9, and 49 is VDD42 similarly.
BVDD connected to, and BE connected to ENH43
NH, 51 is BENL connected to ENL44, 52 is GND
-L45 is connected to BGND-L, 53 is BLATCH connected to LATCH46, 54a, 54b and 54c are GND-
BGND-H, 55 connected to H47a, 47b, 47c is a BCOM connected to the common connection terminal 36. Further, the pattern drawn out from each bonding terminal is connected to each pattern 57 to 62 of the back surface pattern 13 through the through hole 56.

FIG. 10 is a view showing only the back surface pattern, 57 is a pattern to which the BCOM 55 of each IC block is connected (hereinafter referred to as PCOM), and 58 is a pattern to which the BCLOCK 48 of each IC block is connected. (Hereafter, PC
Similarly, 59 is a pattern in which BVDD49 is connected (hereinafter referred to as PVDD), and 60 is BENH.
50 connected pattern (hereinafter referred to as PBENH), 61
Is a pattern in which BENL51 is connected (hereinafter referred to as PBENL), 62 is a pattern in which BLATCH53 is connected (hereinafter referred to as PLATCH), 63 is BG on the surface pattern 13
A pattern in which ND-L52 and BGND-H54a, 54b, 54c are connected (hereinafter referred to as PGND).

FIG. 11 is a diagram showing the wire connection pattern, layout, etc. of the first IC chip 8 to which data is input.
Reference numeral 64 denotes a terminal (referred to as TDATA) that is pattern-connected to the DATA IN 37 and the DIN terminal 28 of the IC chip 8 and the terminal 65 (hereinafter, referred to as the terminal 65 of the wire bonding terminal 15 of the printed circuit board 10).
BDATA) and gold wire 9
The TA terminal 65 is connected to a pattern of 66 (hereinafter referred to as PDATA). Here, these PCOM57, PCLOC
K58, PVDD59, PENH60, PENL61, PLAT
CH62, PGND63 and PDATA66 are routed so as to be connected to the pins of the connector 16. Further, FIG. 20 shows an equivalent circuit of the first embodiment, and 80 shows a circuit (IC circuit) of the IC chip 8.

Next, the operation will be described. DATAIN37 and DATA of IC chip 8 of conventional thermal head
Since the OUT38 position was located on the printed circuit board 10 side, D
In order to provide the wire bonding terminals 15 of the ATA IN 37 and the DATA OUT 38 on the printed circuit board 10 side, it is difficult to provide the nickel and gold plated lead terminals on the connector pin side, so the wire bonding terminals are routed from the wire bonding terminal side. FIG. 12 shows a state in which the printed circuit board 10 of the conventional thermal head is being manufactured, and the printed circuit board 10 is taken in large numbers from one large board 70. Here, 71 is a plating lead, and nickel plating and gold plating are performed by tightening a screw having an electrode connected to a round hole position and immersing it in a plating solution. 72 is BDATA IN
100, BDATA OUT101 plating lead (hereinafter,
The wire bonding side plated lead), 73 is a plated lead drawn from the connector pin direction (hereinafter,
Connector plating lead)), and B1 to B27 are 8
27 blocks of mm pitch are shown, and 27 blocks of the IC chip 8 are shown. Here, the inventor has noticed that the defects of the wire bonding terminals 15 of the printed circuit board 10 in the conventional thermal head are considerably concentrated at the positions located on the wire bonding side plating leads 72, and the plating thickness of the wire bonding terminals 15 investigated. In the wire bonding terminal 15, the terminal without the wire bonding side plated lead 72, that is, the state where the nickel plating and the gold plating are performed from the connector side plated lead 73 has almost no thickness variation, and the nickel thickness is 10 μm.
m ± 2μm Gold plating was about 0.5μm ± 0.1μm, but the nickel thickness of the terminal that is connected to the wire bonding side plating lead 72 and becomes the wire bonding terminal 15 varies from 30μm to 15μm. The closer it was to the position, the thicker it was. This is shown in FIG. Further, it was found that the shapes of these terminals were not flat because the ends were raised, and it was found that these were the cause of the wire bonding failure.
In the first embodiment of the present invention, DATA I on the IC chip 8 is used.
N37 and DATA OUT38 not on the printed circuit board 10 side,
Since the individual electrode terminals 35 are provided on the heating substrate 6 side, the wire bonding terminals 15 do not directly serve as plating leads. Further, since the back surface pattern 12 below the wire bonding terminal 15 is a wide and stable pattern of the PCOM 57, the conditions in the wire bonding thickness direction are uniform.
If the PCOM 57 pattern is not present under the wire bonding terminal 15, the difference in thickness of the copper pattern is about 30 μm, the double-sided tape 19 and the rear surface solder resist layer are not adhered and float, which is not preferable for wire bonding. It is desirable that there is a wide back surface pattern under the wire bonding terminal 15.

Example 2. Next, the inventor investigated the positions of the GND-H 47a, 47b, 47c of the IC chip 8. Originally, the larger the GND-H connection position, the smaller the loss voltage due to the pattern wiring resistance inside the IC chip 8, but
To reduce the number of wire bond connection points, it is set to several points. In the first embodiment, there are three GND-H connection points. Here, the loss voltage when 9 mA was applied to 64 bits of the heating resistor driving terminal DO39 inside the IC chip 8 and the portion of GND-H was examined. The measurement results are shown in FIG. The lower part of Fig. 14 shows GN near DO1, DO32 and DO64.
The layout of the conventional IC chip in which DH is arranged, the above figure is DO
The results are obtained by arranging the GND-H near 12, DO32 and DO54. Maximum 50 mV variation between conventional products
The improvement was about 30 mV, about 40%, and the print results showed less variation. The position of GND-H47 is 2 at the position 16 to 25 bits away from the center.
By setting it at one place in the center and one place, it was within about 40 mV, and it was a position where about 20% of the case at the end could be improved.

Embodiment 3. As a signal arrangement of the IC chip 8, by placing ENH43 next to VDD42,
If the NH43 signal is not needed, PV as shown in Fig. 15
DD59 and PENH60 may be connected, and BVDD49 and BENH50, which are bonding terminals, may be connected, resulting in a simple pattern arrangement.

Example 4. As the signal arrangement of the IC chip 8, the ENL44 is arranged next to the GND-L45 so that when the ENL44 signal is not required, the BENL51, BGND-L52, BGND-H47b, 47 are arranged as shown in FIG.
It is sufficient to connect with c and it is also possible to connect with a pattern, resulting in a simple pattern arrangement.

Example 5. Further, by providing a rectangular pattern for wire bonding recognition as shown by 74 in FIG. 16, it is possible to improve the efficiency of recognition by the wire bonding automatic device. The recognition pattern may be a rectangular dent pattern. The circular recognition pattern is difficult to form a uniform circle by etching a copper pattern, nickel plating, and gold plating, and it is desired that the rectangular pattern has a uniform pattern.

Example 6. Further, as shown in FIG. 17, the signal of the IC chip 8 is struck by two gold wires 9 at a time, so that it becomes possible to prevent the wire bonding failure on the printed circuit board 10 side. The temperature at the time of wire bonding of the printed circuit board 10 is a low temperature due to the allowable temperature of the material of the printed circuit board and the difficulty of heat conduction, which is a low temperature, leading to defective wire bonding. By the way, when the wire bond is defective, IC
Although the chip 8 will be removed and replaced, the wire connection terminal on the heat generating substrate 6 side can be cleaned by removing the gold wire 9, but the wire bonding terminal 15 on the printed circuit board 10 side can remove the gold wire 9. However, when the IC chip 8 is replaced, the IC chip 8 is peeled off from the printed circuit board, making it difficult to reproduce. Therefore, more reliable wire bonding on the printed circuit board 10 side will lead to further improvement in manufacturing yield.

Example 7. Further, FIG. 18 shows a case where the printed circuit board 10 has a single-sided pattern, and the single-sided board 75 can be used by covering the portions other than the wire bonding terminal locations with the solder resist layer.

Example 8. Further, the heat generating substrate 6 may be made large without using the printed circuit board 10 to have a configuration similar to the pattern arrangement as shown in FIG. In this case, PCOM57P
To strengthen the GND58 wiring pattern, for example, a glass frit-based gold paste or silver paste is overprinted on the conductor pattern 3 made of an organic gold paste, and then a necessary portion is exposed with the glass paste to bond the wire with the gold wire 9. Should be done. Also, the connector 15 is 57, 58, 59, 6
The flexible printed circuit board may be pressure-contacted with the 0, 61, and 63 patterns and subjected to thermocompression bonding with an anisotropic conductive film, indium solder, or the like, and then the connector 15 may be soldered to the flexible printed circuit board. Further, the connector may be directly connected to the pattern using indium solder or the like, or may be a pressure contact structure.

Example 9. In Example 1, GND-L45 and G
Although the ND-H47 is connected to form the PGND63, the pin of the connector of the thermal head may be separated and connected in the vicinity of the terminal of the power source of the thermal head using device. Needless to say, the signal pattern wiring is not particularly limited.

Example 10. In the first embodiment, the common electrode pattern width of the comb-shaped portion and the individual electrode pattern width are the same. However, when the resistance value of the heating resistor is low and the current is large, the common electrode pattern width is increased to increase the common electrode pattern width. The loss of the connection pattern can be reduced.

Example 11. As shown in FIGS. 25 and 26, a high conductive film 400 may be further formed. Specifically, after the protective film 5 is formed, a conductive glass paste is screen-printed on the heating resistor 4 and dried and baked to form the protective film 5. The high conductive film 400 is a probe terminal of a part of the common electrode block terminal 32 which is not covered with the protective film 5.
By being connected to 34, static electricity generated during printing can be released to the outside through the common electrode block, and defects due to static electricity of the heating resistor 4 can be prevented.

Embodiment 12 FIGS. 27, 28 and 29 show
FIG. 6 is a plan view of a thermal head according to another embodiment of the present invention. In the conventional thermal head as shown in FIG. 30 and FIG. 31, the protruding adhesive spreads on the common electrode pad 24b along the edge of the protective film 5 and the common electrode pad 24b and the Au wire 9 due to the capillary phenomenon. Could not be connected, or even if it was connected, there was a connection failure such as weak strength. However, as shown in FIG. 27, the problem can be solved by forming the protective film 5 into a mountain shape so as to sandwich the common electrode pad 24b. Further, as shown in FIGS. 28 and 29, if the shape of the protective film 5 is valley-shaped or trapezoidal, the same effect can be obtained.

Embodiment 13 Regarding the connection method of the IC chips, instead of wire bonding, connection using a face-down method using a flip chip IC by solder pump or gold pump, or a tab method using a film, etc. Well, it is not particularly limited.

Example 14 Although the case where the conductor pattern is formed of the organic gold paste with a thickness of 0.5 μm is shown, other conductor materials may be used. In particular, as long as the resistance value of the heating resistor is high, it may be a pattern using a resin paste having a high specific resistance, for example, a metal such as Al or a conductor mixed therein, and is not particularly limited.

Fifteenth Embodiment Further, the operation circuit of the IC chip is not particularly limited, and it may be possible to omit the latch circuit or reduce the number of signal terminals.

[0030]

Since the present invention is constructed as described above, it has the following effects. A common electrode pattern is arranged on the IC chip side and in the opposite direction through the heat generating resistor, the common electrode patterns are connected in a plurality of patterns, and a drive terminal of the heat generating resistor is arranged on the heat generating resistor side of the IC chip. However, since it is not necessary to fold all the bits by connecting to the conductor pattern, the pattern density becomes low and the patterning becomes easy. In particular, when the heating resistor has a strip shape, the loss due to the loss resistance can be reduced by the heat accumulated by the transfer to the adjacent element. Probing points of the common electrode are provided between the heating resistor and the IC chip, so that probing can be performed for each block, reliability is improved, and debris of the thermal paper does not accumulate, which does not lead to poor image quality. In addition, static electricity can be prevented by bringing the high conductive film into contact with the probing point. By partially changing the insulating pattern between the IC chip and the common electrode pattern,
It is possible to prevent the adhesive from squeezing out, improve the yield, and increase the productivity. On the other hand, through the heating resistor, I
A common electrode pattern is arranged on the C chip side and in the opposite direction, and the common electrode pattern is connected by N patterns,
By connecting the external common electrode pattern connected to the IC chip side common electrode pattern from one side and connecting to the connector portion for connection, the device can be downsized, and the number of printed circuit boards per fixed area can be reduced. Can be increased. By arranging the data input terminal, data output terminal, and drive terminal in the IC chip in one direction and connecting them to the conductor pattern on the insulating board to arrange the print data input / output terminals on the heat generating board, the heat generating board and the print can be printed. Prevents disconnection due to the difference in coefficient of thermal expansion from the wiring board,
The yield can be improved. By grouping the drive terminal arrangements in the IC chip and arranging the common electrode connection pattern between the groups, the gold wire does not contact the connection pattern and reliability is improved. The reliability can be further improved by forming the driving terminals of the heat generating resistors of the IC chip into M and 2M groups arranged at the same pitch. Further, by disposing the common electrode below the IC chip, the area of the heat generating substrate can be effectively used, and the number of sheets taken per unit substrate is increased. I
By connecting the drive signal terminal of the C chip to a conductor pattern on another board and arranging a wide conductor pattern below the connected conductor pattern position, the bottom of the wire stitch portion of the printed wiring board becomes flat, and the double-sided tape Uniform contact with By making the wide conductor pattern of another substrate a common electrode pattern connected to the common electrode pattern on the insulating substrate, the adhesion with the double-sided tape is further improved. Since the conductor pattern to which the drive signal terminal of the IC chip of the other substrate is connected does not extend to the substrate end on the IC chip side, the plating lead of the printed circuit board becomes unnecessary and the yield is improved. A heating resistor driving terminal, a print data input terminal, and a print data output terminal are arranged on one side in the longitudinal direction of the IC chip, a ground terminal is arranged near the center, and an I terminal is arranged on the other side.
By arranging the C chip drive signal terminal, the pattern arrangement of the IC chip can be facilitated, the GND pattern can be widened in the center, the loss of the GND pattern in the IC can be reduced, and the GND at any place can be reduced. It is possible to take. The driving terminals of the heat generating resistors of the IC chip are composed of M and 2M groups arranged at the same pitch, and the intervals between the groups are different from the arrangement pitch of the driving terminals and have the same pitch, thus improving the yield. There are 3 ground terminals, 1
The location is located at the center of the drive terminals of the L heating resistors, and the other two locations are located at L / 4 to 2 from the center drive terminal location.
By separating the number of L / 5 terminals, it is possible to reduce the variation in loss voltage, which in turn reduces the variation in printing, which leads to an improvement in printing quality. An IC chip driving power supply terminal is adjacent to a signal terminal connected to a pull-down resistor inside the IC chip of the IC chip driving signal terminal, and an IC is adjacent to a signal terminal connected to a pull-up resistor inside the IC chip. By using the ground side terminal of the chip drive power source, the conductor pattern wiring to be connected becomes easy. Since the rectangular pattern is provided on the terminal serving as the connection pattern of the separate substrate, the recognition rate in pattern recognition is increased, and the yield is mainly improved. Further, since the separate substrate and the IC chip drive signal terminal are connected at two or more points, the reliability is further improved. In the comb-shaped part where the common electrode and the individual electrode alternate, if the resistance value of the heating resistor is low and the current is large, the common electrode pattern width can be made wider than the individual electrode width to reduce the loss of the common electrode pattern. However, the image quality can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a thermal head according to an embodiment of the present invention.

FIG. 2 is a sectional view of a thermal head according to an embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the thermal head according to the embodiment of the present invention.

FIG. 4 is a diagram showing a conductor pattern of a heat generating substrate of a thermal head according to an embodiment of the present invention.

FIG. 5 is a diagram showing a conductor pattern and a heating resistor of a heating substrate of a thermal head according to an embodiment of the present invention.

FIG. 6 is a diagram showing a protective film pattern of a heat generating substrate of a thermal head according to an embodiment of the present invention.

FIG. 7 is an IC chip mounting diagram on a heat generating substrate of a thermal head according to an embodiment of the present invention.

FIG. 8 is a circuit diagram of an IC chip for driving a thermal head according to an embodiment of the present invention.

FIG. 9 is another IC chip mounting diagram of a thermal head according to an embodiment of the present invention.

FIG. 10 is a rear surface pattern view of another substrate of the thermal head according to the embodiment of the present invention.

FIG. 11 is a mounting view of another substrate of the thermal head and the leading IC chip according to the embodiment of the present invention.

FIG. 12 is a diagram showing a plating step in the manufacturing process of another substrate of the conventional thermal head.

FIG. 13 is a diagram showing variations in terminal thickness due to plated leads.

FIG. 14 is a diagram showing a ground terminal position and a loss in the IC chip.

FIG. 15 is a pattern diagram of another substrate of the thermal head according to another embodiment of the present invention.

FIG. 16 is a pattern diagram of another substrate of the thermal head of another embodiment of the present invention.

FIG. 17 is a thermal head I of another embodiment of the present invention.
It is a C chip mounting view.

FIG. 18 is a diagram showing a thermal head of another embodiment of the present invention.

FIG. 19 is a diagram showing a thermal head of another embodiment of the present invention.

FIG. 20 is an equivalent circuit diagram of a thermal head according to an embodiment of the present invention.

FIG. 21 is a perspective view showing a conventional thermal head.

FIG. 22 is a sectional view showing a conventional thermal head.

FIG. 23 is an equivalent circuit diagram showing a conventional thermal head.

FIG. 24 is a diagram showing an IC chip of a conventional thermal head.

FIG. 25 is a diagram showing manufacturing steps of a thermal head according to another embodiment of the present invention.

FIG. 26 is a diagram showing a protection pattern and a high conductive film pattern of a heat generating substrate of a thermal head according to another embodiment of the present invention.

FIG. 27 is a plan view of a thermal head according to another embodiment of the present invention.

FIG. 28 is a plan view of a thermal head according to another embodiment of the present invention.

FIG. 29 is a plan view of a thermal head according to another embodiment of the present invention.

FIG. 30 is a plan view of a conventional thermal head.

FIG. 31 is a plan view of a conventional thermal head.

[Explanation of symbols]

 1 Alumina Ceramic Substrate 2 Heat Storage Layer 3 Conductor Pattern 4 Heating Resistor 5 Protective Film 6 Heating Board 7 Adhesive 8 IC Chip 9 Gold Wire 10 Printed Circuit Board 11 Backside Solder Resist Layer 12 Backside Pattern 13 Surface Pattern 14 Surface Solder Resist Layer 15 Bonding Terminal 16 Connector 17 Solder 18 Support 19 Double-sided tape 20 Recording paper 21 Platen roller 22 Protective resin 23 Cover 24a Edge common electrode 24b IC lower common electrode 25 Individual electrode 26a Individual electrode group a 26b Individual electrode group b 27 Common electrode connection pattern 28 DIN terminal 29 DOUT terminal 30 Recognition pattern 31 Position recognition pattern 32 Common electrode block terminal 33 Comb-shaped portion 34 Probe terminal 35 Individual electrode terminal 36 Common connection terminal 37 DATA OUT 38 DATA IN 39 DO 40 COM interval 41 CLOCK 42 VDD 43 ENH 44 ENL 45 GND-L 46 LAT H 47a GND-H 47b GND-H 47c GND-H 48 BCLOCK 49 BVDD 50 BENH 51 BENL 52 BGND-L 53 BLATCH 54a, 54b, 54c BGND-H 55 BCOM 56 56 Through-hole 57 PCOM 58 PECL 59 61 VDD 60PLOCK 59NH 62 PLATCH 63 PGND 64 TDATA 65 BDATA 66 PDATA 70 Large-sized board 71 Plating lead 72 Wire bonding side Plating lead 73 Connector side plating lead 74 Square pattern 75 Single-sided pattern 80 IC circuit 90 Common reinforced part 100 BDATA IN 101 BDATA OUT 300 Conductor layer 400 High conductive film

Claims (20)

[Claims] 1. A thermal head comprising a conductor pattern, M heat generating resistors on a substrate, and a plurality of IC chips for driving the heat generating resistors based on print information. , A common electrode pattern is arranged on the IC chip side and in the opposite direction, the common electrode patterns are connected by N patterns, and a drive terminal of the heat generating resistor is arranged on the heat generating resistor side of the IC chip. A thermal head characterized by being connected to. 2. The thermal head according to claim 1, wherein the heating resistor is a strip-shaped continuous resistor. 3. The thermal head according to claim 1, wherein a probing point of a common electrode is provided between the heating resistor and the IC chip. 4. A thermal head comprising a high conductive film in contact with a probing point. 5. A space between the IC chip and the IC chip, comprising a common electrode, an insulating pattern provided on the common electrode, and an adhesive provided to set an IC chip on the insulating pattern. In the structure in which the common electrode pattern is connected to the external common electrode pattern, the insulation pattern on the common electrode pattern between the IC chips is different from the insulation pattern width on the lower surface of the IC chip. 6. A thermal head comprising a conductor pattern, M heat generating resistors on a substrate, and a plurality of IC chips for driving the heat generating resistors based on printing information. , A common electrode pattern is arranged on the IC chip side and in the opposite direction, and the common electrode pattern is connected by N patterns so that it is parallel to the common electrode pattern connected to the IC chip side common electrode pattern. The thermal head is characterized in that the thermal head is connected to the external common electrode pattern arranged in, and is connected to the connecting connector portion in a pattern pattern that is substantially orthogonal. 7. The thermal head according to claim 1, wherein the print data input terminal and the print data output terminal are arranged on the heating resistor side of the IC chip. 8. The driving terminal of the heating resistor of the IC chip,
3. The thermal head according to claim 1, wherein the thermal head comprises a plurality of groups arranged at the same pitch, and the common electrode connection pattern is arranged so as to be located between the groups. 9. The thermal head according to claim 8, wherein the driving terminals of the heating resistor of the IC chip are composed of M groups arranged at the same pitch at the end portions and 2M at the central portion. 10. The thermal head according to claim 1, wherein a common electrode is arranged below the IC chip. 11. A drive signal terminal of an IC chip is connected to a conductor pattern of another substrate, and a wide conductor pattern is arranged below a conductor pattern position to be connected. The thermal head according to any one of 6 to 10. 12. The thermal conductor according to claim 1, wherein the wide conductor pattern of the other substrate is a common electrode pattern connected to the common electrode pattern on the insulating substrate. head. 13. The thermal head according to claim 1, wherein the conductor pattern to which the drive signal terminal of the IC chip on the other substrate is connected is not extended to the substrate end on the IC chip side. .. 14. A heating resistor driving terminal, a print data input terminal, and a print data output terminal are arranged on one side in the longitudinal direction of the IC chip, a ground terminal is arranged near the central portion, and an IC chip drive signal terminal is arranged on the other side. An IC chip for a thermal head, characterized in that 15. The driving terminal of the heating resistor of the IC chip is M.
1M and 2M groups arranged at the same pitch, and the interval of each group is different from the arrangement pitch of the drive terminals, and the data input terminals and the data output terminals are arranged at the end of the IC chip. The IC chip of the thermal head according to claim 8, 16. A ground terminal is provided at three locations, and one location is L
16. Each of the heating resistors is located at the center of the driving terminal and the other two positions are separated from the central driving terminal position by L / 4 to 2L / 5 terminals. The IC chip of the thermal head described above. 17. A signal connected to a pull-up resistor inside the IC chip, with an IC chip drive power supply terminal adjacent to a signal terminal connected to a pull-down resistor inside the IC chip of the IC chip drive signal terminal. Adjacent to the terminal I
An IC chip for a thermal head, which is used as a ground side terminal of a C chip drive power source. 18. A rectangular pattern for pattern recognition is provided on a connection terminal portion of another substrate connected to a drive signal terminal of an IC chip, and the square pattern for pattern recognition is provided.
Any one of the thermal heads. 19. The thermal head according to claim 1, wherein the number of connection points between the drive signal terminal of the IC chip and the conductor pattern is two or more. 20. The common electrode pattern width is wider than the width of the individual electrode in the comb-shaped portion in which the common electrode and the individual electrode are alternately arranged.
19. The thermal head according to any one of 19.