JPH07266598A - Thermal printing head and its manufacture - Google Patents

Abstract

PURPOSE:To ensure that the pitch between pads for probe contact can be made a desired pitch without depending upon the pitch between output pads on a drive IC to be used by forming the pad for probe contact in addition to a pad for wire bonding. CONSTITUTION:A pad for probe contact 13 is formed by using each individual electrode wiring 7 of larger thickness, in the intermediate part of individual electrode wiring 7, that is, the intermediate part between one end part communicating with a thermal part 2 and the other end part where a pad for wire bonding 8 is formed. In this case, the pad for probe contact 13 is formed in a zigzag pattern so that a small interpad pitch is maintained and further, a specified width is secured. The pitch P2 between the pads for probe contact is set larger than the pitch P1 between the pads for wire bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head and a method for manufacturing the same, which is performed for an open / short test between individual electrode wirings performed in a manufacturing process and for setting a resistance value of a heating portion to a desired value. Pulse trimming, which is more efficient and accurate.

[0002]

2. Description of the Related Art FIG. 7 shows a partial schematic plan view of a so-called thick film type thermal print head 1. In the figure, reference numeral 2 indicates a heat generating portion arranged along one side edge of the insulating substrate 3 made of ceramic or the like. This heating part 2
Are subdivided substantially in the longitudinal direction and are individually driven to generate heat by the drive ICs 4 which are in charge of several heat generating portions. In the figure, reference numeral 5 indicates a common electrode pattern, and reference numeral 6 indicates a terminal for inputting and outputting a control signal and a print input signal.

As shown in more detail in FIG. 8, comb-teeth-shaped electrode wirings 5a extend from the common electrode pattern 5 at equal intervals, and individual electrode wirings 7 are provided between the common electrode wirings 5a. One end of is stuck in. And
Heat generated by printing and firing using a resistor paste containing ruthenium oxide or the like as a main component so as to cover the comb-teeth-shaped common electrode wirings 5a ... The resistor 2a is arranged.

Each of the individual electrode wirings 7 extends from the heating resistor 2a in the direction opposite to the common wiring pattern 5, and a wire bonding pad 8 is formed at the other end thereof. ing.

For example, 200 dpi, that is, 1 m
In order to arrange the 8-dot heat generating portion 2 in the length of m, the pitch of the individual electrode wirings 7 that dig under the heat generating resistor 2a is as extremely small as 0.125 mm. Along with this, the comb-shaped common electrode wiring 5 is formed.
The a and the individual electrode wiring 7 have an extremely fine pattern. Such fine wiring is formed by printing and baking, for example, resinate gold on the glaze layer formed on the insulating substrate 9 to form a conductor film, and then an unnecessary portion is removed by a photo-etching method. It is formed by such a method.

The wire bonding pad 8 formed on the other end of each individual electrode wiring 7 is connected to the output pad 10 on the drive IC 4 by wire bonding. In order to properly perform wire bonding, a pad surface having a predetermined width is required.
In the example shown in (1), both the wire bonding pads 8 of each individual electrode wiring 7 and the output pads 10 on the drive IC 4 are arranged in a staggered pattern.

The pad pitch P ₁ of the wire bonding pads 8 is set depending on the output pad pitch P ₀ on the drive IC 4 used.
The drive IC 4 is a semiconductor device manufactured by a wafer process, and has been downsized and highly integrated. Recently, 64, 96, 128 are formed on one drive IC.
It has been practiced to arrange as many as 144 output pads. Therefore, the pitch between the output pads on the drive IC 4 is rarely restricted by other factors, and the pitch tends to be arranged as narrow as possible.

[0008]

By the way, as described above, since the individual electrode wiring 7 is extremely fine and the individual electrode wiring 7 is formed by the photo-etching method, Due to a problem that occurs during the etching process, a problem may occur in which the adjacent individual electrode wirings 7 are electrically connected to each other. Substrates with such defects should be eliminated in the manufacturing process,
The inspection for such defects is conducted as follows.

That is, using a probing means called a probe card 11, which is schematically shown in FIGS. 3 and 4, a plurality of probes 12 of the probe card 11 are connected to the wire bonding pad 8 of the individual electrode wiring 7. The above-mentioned inspection is carried out by contacting each of the individual electrode wirings with each other and applying a predetermined current to each individual electrode wiring. Above probe
The pitch between the probes 12 of the card 11 corresponds to the pitch between the wire bonding pads 8.

By the way, the number of the probes 12 included in the probe card 11 is limited to a predetermined number due to the memory capacity of the inspection equipment. For example, in some types of probe card 11, the probe 12
Is 32, and therefore, the above-mentioned inspection is divided into a plurality of times and sequentially performed.

64 output pads 1 per driving IC 4
When 0 is provided, the number of wire bonding pads 8 to be wire bonded to the output pad on the one drive IC 4 is 64. in this case,
In the inspection using the probe card 11, the wire bonding pad 8 in one drive IC mounting portion is inspected twice. Further, in the case of constructing a thermal print head for performing B4 size printing, for example, a drive IC having 64 output pads is used.
Two pieces are arranged, and in this case, therefore, the inspection using the above-mentioned probe card is sequentially performed in 64 times.

In order to perform such an inspection, a mechanism for pitch-feeding the probe card 11 to the substrate 3 in the substrate longitudinal direction is required. However, the positioning accuracy of such a mechanical pitch feed mechanism is 10 at most.
Since the limit is μm, the probe that is pitch-fed when performing the above-mentioned inspections in multiple times
There is a problem that an error in the substrate longitudinal direction is accumulated between each probe 12 of the card 11 and the wire bonding pad 8, so that the probe 12 is not properly contacted with the wire bonding pad 8.

For example, the pitch between the output pads 10 of a certain type of drive IC 4 is 58 μm. Then, the length of 32 pads is 1856 μm. In this case, the probe 12 can be accurately brought into contact with all the wire bonding pads only when the probe card 11 is moved at a pitch of 1856 μm.

However, as described above, the positioning accuracy of the mechanism capable of mechanical pitch feeding is the maximum unit of 10 μm, and the positioning accuracy cannot be further increased. Therefore, in performing the above-described inspection while sequentially contacting the probe cards with the wire bonding pads, it may not be possible to achieve accurate probe contact.

The present invention has been devised under the above circumstances, and in the manufacture of a thermal print head, a probe is attached to a large number of individual electrode wirings which are extended at one end thereof to a heat generating portion. It is an object of the present invention to make such inspection more accurate and efficient in contacting and inspecting.

[0016]

In order to solve the above problems, the present invention takes the following technical means.

That is, according to the invention described in claim 1 of the present application, an insulating substrate, a large number of heat generating portions arranged in a row on the insulating substrate, and one end of each heat generating portion formed on the insulating substrate. Between the output pads and the corresponding wire bonding pads on the upper surface, and a large number of individual electrode wirings that are electrically connected to each other and have wire bonding pads formed on the other end. In a thermal print head including a drive IC to be wire-bonded, a probe contact pad is formed on the individual electrode wiring separately from the wire bonding pad, and a pitch between pads of the probe contact pad is formed. Is different from the above wire bonding pad pitch.

The probe contact pad may be formed closer to the heat generating portion than the wire bonding pad in each individual electrode wiring (claim 2), or extended from the wire bonding pad to the drive IC side. It may be formed at the defined portion (claim 3).

When the probe contact pad is formed at a portion extending from the wire bonding pad to the drive IC side as described above, the probe contact pad is mounted on the insulating substrate after the inspection is completed. Since it is hidden by the drive IC (claim 4), the provision of such probe contact pads does not increase the substrate size.

Since the pitch between the probe contact pads is different from the pitch between the wire bonding pads, the pitch between the probe contact pads corresponds to the moving accuracy of the probing means for holding a plurality of probes. Can be set (Claim 5).

The invention described in claim 6 defines the method for manufacturing the thermal print head according to claim 1, wherein the individual electrode wiring is provided separately from the wire bonding pad. A probe contact pad having a pad pitch different from the pad pitch of the wire bonding pad is formed, and a probing means for holding a plurality of probes at a pitch corresponding to the probe contact pad pitch is used. The inspection is performed through the individual electrode wiring while sequentially contacting the probes of the probing means with a predetermined number of the probe contact pads.

The inspection is, for example, an open / short inspection between individual electrode wirings (claim 7).

Further, the invention described in claim 8 is the method for manufacturing a thermal print head according to claim 1, wherein the individual electrode wiring is provided with the wire bonding pad separately from the wire bonding pad. A probe contact pad having a pad pitch different from the pad pitch of is formed in advance, and a predetermined number of the probe contact pads are held by using a probing means that holds a plurality of probes at a pitch corresponding to the probe contact pad pitch. While sequentially contacting the probe of the probing means with the probe contact pad, a high-voltage current is caused to flow to each heating portion through the individual electrode wiring, and pulse trimming is performed to set the resistance value of each heating portion to a desired value. That is.

[0024]

As can be seen from the invention described in claim 1, according to the present invention, in the individual electrode wiring, in addition to the pad for wire bonding, a pad different in pad pitch from the pad for wire bonding is used. It is characterized in that probe contact pads having an inter-pitched pitch are formed. As described in the section of the prior art, the pitch between the wire bonding pads provided on the individual electrode wiring must be set depending on the pitch between the output pads on the drive IC used. However, in the present invention, since the probe contact pads are formed separately from the wire bonding pads, the pitch between the probe contact pads depends on the pitch between the output pads on the driving IC used. It is possible to set a desired pitch without performing the above.

When a probe card holding a plurality of probes is used to perform an inspection or the like, the operation of contacting the probe with the wiring of each individual electrode wiring is divided into a plurality of times depending on the capacity of the memory of the inspection device. May need to be done. In this case, the probe card is pitch-fed in the longitudinal direction of the print head. The pitch between the probe contact pads can be set in accordance with the positioning accuracy of the mechanism for feeding the pitch. As a result, the displacement between the probe and the probe contact pad is eliminated, and the inspection or the like can be performed accurately.

When the probe contact pad is formed closer to the heat generating portion than the wire bonding pad as in the invention of claim 2, the probe contact pad is provided on the upper surface of the substrate even after the drive IC is mounted on the substrate. The probe or the like of the probe card can be brought into contact with it to perform an inspection or the like.

According to a third aspect of the present invention, the probe contact pad is driven by a wire bonding pad I
When formed at the portion extended to the C side, the pitch between probe contact pads can be further expanded without being limited by the adjacent individual electrode wiring.

When the probe contact pad is formed as in the invention of claim 3 as in the invention of claim 4,
The probe contact pad is formed on the drive IC mounting area, but the drive IC may be mounted on the upper surface of the drive IC mounting area without any problem. Therefore, the probe contact pad is formed, resulting in an increase in the size of the substrate. Can be avoided.

Since the probe contact pad can be formed when each individual electrode wiring is formed, there is no problem that the number of manufacturing steps is increased to carry out the present invention.

Other features of the present invention will be apparent from the following description of preferred embodiments with reference to the drawings.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
A detailed description will be given with reference to FIGS. 1 to 6. In addition,
In these drawings, parts or members equivalent to those in the drawings starting from FIG. 7 are designated by the same reference numerals.

FIG. 1 is an enlarged plan view showing an essential part of the first embodiment of the present invention. That is, FIG. 1 shows a plan view of the pattern of the individual electrode wiring 7 which is handled by one drive IC 4 in the thermal print head 1. The overall structure of the thermal print head 1 is
This is similar to that already described with reference to FIGS. 7 and 8.

This example shows a case where one drive IC 4 is in charge of driving 64 heat generating parts 2. One end is electrically connected to 64 heat generating parts 2 which are continuous in FIG. 64 individual electrode wirings 7 are formed on the substrate. Each individual electrode wiring 7 extends toward the other end while slightly narrowing the mutual distance, and a thick wire bonding pad 8 is formed in a zigzag shape at each other end.

The wire bonding pads 8 are provided to connect the output pads 10 of the drive IC 4 by wire bonding, and therefore the pitch P ₁ between the wire bonding pads is set.
2 is set in correspondence with the pitch P ₀ between the output pads 10 formed on the drive IC 4 to be used, as shown in FIG. As described above, the drive IC 4 is becoming smaller and higher in density, and the pitch between the output pads is set depending on such a request. Therefore, the pitch is set in units of 1 μm. It is possible.

In one example, the output pad pitch, that is, the wire bonding pad pitch P ₁ is set to 58 μm.

The wire bonding pads 8 and the output pads 10 are arranged in a zigzag manner in order to obtain a predetermined pad width while ensuring the small pad pitch P ₁ as described above.

On the other hand, an intermediate portion of each of the individual electrode wirings 7, that is, an intermediate portion between one end portion that conducts to the heat generating portion 2 and the other end portion where the wire bonding pad 8 is formed, is used for probe contact. The pad 13 is formed by thickening each individual electrode wiring 7. Also in this case, the probe contact pads 13 are formed in a zigzag shape in order to maintain a predetermined pitch while maintaining a small pad pitch. The pitch P between the probe contact pads
₂ is larger than the pitch P ₁ between the wire bonding pads. The pitch P ₂ between the probe contact pads can be set as follows, for example.

Each probe 12 of the probe card 11 as shown in FIGS. 3 and 4 is brought into contact with the probe contact pad 13 to measure the current flowing through the individual electrode wiring 7. Various inspections are performed. Due to the memory capacity of the inspection device connected to the probe card 11, the number of the probes 12 included in the probe card 11 is limited, and 32 probes 12 are provided in the example shown in the figure. Of course, the probe pitch P ₃ of this probe card corresponds to the probe contact pad pitch P ₂ . Using such a probe card 11, the 6 shown in FIG.
In order to perform the inspection via the probe contact pads 13 provided on the four individual electrode wirings 7, it is necessary to perform the inspection divided into the left half and the right half in FIG. Therefore, it is necessary to feed the probe contact pads 13 by 32 pitches by a feed mechanism (not shown) that supports the probe card. When performing such pitch feed mechanically, the positioning accuracy is 10 μm.
The degree is the limit. The pitch between the probe contact pads is determined according to the positioning accuracy of the feed mechanism.

In the above example, the pitch P ₁ between the wire bonding pads is 58 μm, so the 32 pitches between the wire bonding pads are 1856 μm. Since it is impossible to determine such a positioning in units of 1 μm in the pitch feed mechanism of the probe card 11, for example, the distance of 32 pitches of the pitch P ₂ between the probe contact pads is, for example, larger than that of 1856 μm. For example, it is set to 1920 μm, which is a slightly larger multiple of 10 μm. In this case, the pitch P ₂ between the probe contact pads is 60 μm.
However, since the individual electrode wiring is formed by photo-etching, it is easy to set the pitch.

As a result, the 64 probe contact pads 13 shown in FIG. 1 are inspected by contacting the probe card shown in FIGS. After doing this, move this probe card to the right of 1920 μm and
It suffices to inspect the two probe contact pads. The moving distance of the above probe card is 1
Since it is a multiple of 0 μm, accurate probe contact with the probe contact pad can be performed when the positioning accuracy of the mechanism for pitch feeding the probe card is in the unit of 10 μm.

The length of the 64 heat generating parts is 125 μm.
Since m × 64 = 8000 μm, which is a multiple of 10 μm, the probe contact pad arranged in the same manner as in FIG. 1 having 64 individual electrode wirings handled by the adjacent drive IC has a probe. -The card can be accurately positioned to perform a predetermined inspection.

As the above inspection, for example, there is an open / short inspection between the individual electrode wirings 7. As described above, such a fine wiring pattern on the substrate is formed by the photo-etching method after the conductor film is formed. Therefore, the fine wiring patterns are adjacent to each other due to, for example, a defect in the photomask. May cause short circuit between wires,
It is impossible to visually determine such a short circuit. Since such a defect is a serious problem as a thermal print head, a substrate having such a defect should be eliminated, and for this reason, such an open / short inspection is performed.

As shown in FIG. 2, with respect to the substrate judged to be good after the above inspection is completed, the drive I is placed at a predetermined position adjacent to the wire bonding pad 8 for every 64 wires.
C4 is mounted, and the corresponding output pad 10 and the corresponding wire bonding pad 8 are connected by wire bonding.

In the example shown in FIGS. 1 and 2, the probe contact pads 13 ... Are connected to the individual electrode wirings 7.
Since it is formed in the intermediate portion of the above, as shown in FIG. 2, there is an advantage that a necessary inspection can be performed via the probe contact pad 13 even after the drive IC 4 is mounted on the substrate. .

5 and 6 show a second embodiment of the present invention. In this embodiment, each probe contact pad 13 is formed at the end of the wire extending from the wire bonding pad 8 to the drive IC side. Even in this case, the pitch P ₂ between the probe contact pads is equal to the pitch P ₁ between the wire bonding pads.
It is similar to the embodiment shown in FIGS. 1 and 2 in that it is larger than the above.

In this example, there is an advantage that the pitch P ₂ between the probe contact pads can be set wider. This is because, unlike the embodiment shown in FIGS. 1 and 2, the distance between adjacent individual electrode wirings is not limited.

Then, the probe contact pad 13
6 is covered by the drive IC 4 mounted on the substrate adjacent to each wire bonding pad 8, as shown in FIG. Therefore, by providing the probe contact pad 13 in an extended shape, the problem that the substrate width dimension is expanded cannot occur.

Also in the second embodiment, it is possible to accurately perform an inspection such as an open / short inspection using the probe card 11 shown in FIGS. 3 and 4.

The above-mentioned processing is carried out by using the probe card 11 as shown in FIG. 3 or 4 and bringing the probe 12 into contact with the probe contact pad 13 of each individual electrode wiring. In addition to the open / short inspection, there is a so-called pulse trimming process.

The pulse trimming is an operation in which a current having an excessive voltage is applied to the heat generating portion 2 in a pulsed manner to change the quality of the heat generating portion 2 and increase or decrease its resistance value. The probe card as shown in FIGS. 3 and 4 is used to pass the trimming current as described above between the common electrode and each individual electrode wiring.

Also in this case, the probe card 1
The operation required for No. 1 is the same as in the case of the open / short inspection described above. Therefore, according to the invention of the present application, accurate contact between the probe and the individual electrode wiring is obtained even when performing such pulse trimming. It is possible to perform pulse trimming properly and swiftly while ensuring the above.

Of course, the scope of the present invention is not limited to the above-mentioned embodiments. As the types of thermal print heads, there are thin-film thermal print heads as well as thick-film thermal print heads. In either case, there is a wire between the individual electrode wiring and the drive IC mounted on the substrate. The present invention can be applied to all thermal print heads of the bonded type and their manufacturing methods.

Further, in the embodiment, the pitch P ₂ between the probe contact pads is set larger than the pitch P ₁ between the wire bonding pads, but it may be set smaller.

Further, in the embodiment, both the wire bonding pads and the probe contact pads are arranged in a zigzag pattern, but if possible, they may be arranged in a straight line.

[Brief description of drawings]

FIG. 1 is an enlarged plan view showing an essential part of a first embodiment of the present invention, in which a pattern of individual electrode wirings which one driving IC is in charge of is shown.

FIG. 2 shows the first embodiment of the present invention and shows a state in which wire bonding is performed between the wire bonding pad of each individual electrode wiring and the drive IC.

FIG. 3 is a schematic plan view showing an example of a probe card.

FIG. 4 is a schematic side view showing an example of a probe card.

FIG. 5 is an enlarged plan view showing an essential part of a second embodiment of the present invention, in which a pattern of individual electrode wirings handled by one drive IC is shown.

FIG. 6 shows a second embodiment of the present invention, and shows a situation in which the probe contact pad is finally covered by the drive IC.

FIG. 7 is a partial plan view schematically showing a typical form of a thermal print head.

FIG. 8 is a schematic plan view showing in more detail a typical form of a thick film type thermal print head.

[Explanation of reference numerals] 1 thermal print head 2 heat generating part 4 driving IC 7 individual electrode wiring 8 wire bonding pad 10 output pad 11 probe card 12 probe 13 probe bonding pad

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B41J 3/20 114 C

Claims (8)

[Claims] 1. An insulating substrate, a large number of heat generating portions arranged in a row on the insulating substrate, one end electrically connected to each heat generating portion formed on the insulating substrate, and a wire at the other end. A thermal print provided with a large number of individual electrode wirings having bonding pads formed thereon, a drive IC mounted on the insulating substrate, and each output pad and a corresponding wire bonding pad being wire-bonded between the output pads on the upper surface. In the head, a probe contact pad is formed on the individual electrode wiring separately from the wire bonding pad,
The thermal print head is characterized in that a pitch between pads of the probe contact pad is different from a pitch between pads of the wire bonding pad. 2. The thermal print head according to claim 1, wherein the probe contact pad is formed closer to the heat generating portion than the wire bonding pad in each individual electrode wiring. 3. The thermal print head according to claim 1, wherein the probe contact pad is formed at a portion of each individual electrode wiring extending from the wire bonding pad to the drive IC side. 4. The thermal print head according to claim 3, wherein the probe contact pad is hidden by the drive IC. 5. The pitch between pads for contacting each probe is set corresponding to the relative movement accuracy of the probing means for holding a plurality of probes with respect to the insulating substrate.
The thermal print head according to claim 1. 6. An insulating substrate, a plurality of heat generating portions arranged in a row on the insulating substrate, one end connected to each heat generating portion and formed on the insulating substrate, and a wire at the other end. Thermal printing provided with a large number of individual electrode wirings having bonding pads formed thereon, a driving IC mounted on the insulating substrate and having wire bonding between the output pads on the upper surface and the corresponding wire bonding pads. In the head manufacturing method, a probe contact pad having a pad pitch different from the pad pitch of the wire bonding pad is formed on the individual electrode wiring separately from the wire bonding pad. , Using a probing means for holding a plurality of probes at a pitch corresponding to the pitch between the probe contact pads, While sequentially contacting the probe of the probing means to said probe contact pads by several and performing an inspection via the individual electrode wires, method of manufacturing the thermal print head. 7. The method according to claim 6, wherein the inspection is an open / short inspection of the individual electrode wiring. 8. An insulating substrate, a large number of heat generating portions arranged in a row on the insulating substrate, one end electrically connected to each heat generating portion and formed on the insulating substrate, and a wire at the other end. Thermal printing provided with a large number of individual electrode wirings having bonding pads formed thereon, a driving IC mounted on the insulating substrate and having wire bonding between the output pads on the upper surface and the corresponding wire bonding pads. In the head manufacturing method, a probe contact pad having a pad pitch different from the pad pitch of the wire bonding pad is formed on the individual electrode wiring separately from the wire bonding pad. , Using a probing means for holding a plurality of probes at a pitch corresponding to the pitch between the probe contact pads, Pulse trimming in which a high-voltage current is applied to each heat-generating portion through the individual electrode wiring while sequentially contacting the probes of the probing means to the probe-contacting pads, and the resistance value of each heat-generating portion is set to a desired value. A method of manufacturing a thermal print head, comprising: