JP2022029196A - Ic chip mounting structure, thermal printhead, and manufacturing method of thermal printhead - Google Patents

Abstract

To provide a thermal printhead having an IC chip mounting structure suitable for preventing defects during flip chip mounting.SOLUTION: A thermal printhead A1 includes a support member including a glaze layer 2 having a main surface 21 facing one side in the z direction (thickness direction), and a wiring layer 3 arranged on the main surface 21, an IC chip with a mounting surface 61, and a plurality of conductive bonding materials 62 arranged on the mounting surface 61, and the IC chip 6 has a mounting structure in which the IC chip 6 is flip-chip mounted on the support member. The support member is arranged correspondingly to the plurality of conductive bonding members 62 and includes a plurality of pad portions 38 including at least two concave pad portions 381. The concave pad portion 381 includes a bottom surface 312 and an inner wall surface 322 facing the bottom surface 312 when viewed in the z direction, and the inner wall surface 322 is composed of the wiring layer 3.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a mounting structure of an IC chip, a thermal print head having the mounting structure, and a method for manufacturing the thermal print head.

Patent Document 1 discloses an example of a conventional thermal print head. The thermal printhead disclosed in the document includes a substrate, a glaze layer, an electrode layer (wiring layer), a heat generation resistor (resistor layer), and a drive IC (IC chip). The substrate is a plate-shaped member made of an insulating material, and is made of a ceramic such as alumina (Al ₂ O ₃ ), for example. The glaze layer is formed on the surface of the substrate and is made of, for example, glass. The wiring layer is formed on the glaze layer, and constitutes a current path for selectively passing a current through the resistor layer. The resistor layer has a plurality of heat generating portions arranged in the main scanning direction. The IC chip controls the current flowing through each heat generating portion.

In the thermal printhead disclosed in Patent Document 1, the IC chip is mounted on the substrate by flip-chip mounting. A plurality of conductive bonding materials made of, for example, solder bumps are provided on the mounting surface of the IC chip facing the substrate. A plurality of pad portions are provided in the wiring layer, and when the IC chip is mounted on the substrate, the IC chip is arranged on the wiring layer by a mounter, and the plurality of conductive bonding materials and the plurality of pad portions are temporarily attached. do. Then, the plurality of conductive bonding materials are melted by the reflow treatment, and the plurality of pad portions and the plurality of conductive bonding materials are bonded. According to such an IC chip mounting structure, a plurality of conductive bonding materials of the IC chip and a plurality of pad portions of the wiring layer can be collectively bonded. Further, it is possible to narrow the pitch of the individual wiring leading to each of the plurality of pad portions, and it is also suitable for miniaturization of wiring.

However, if the mounting position of the IC chip at the time of mounting the flip chip is deviated, the conductive bonding material may come into contact with or be bonded to a pad portion or individual wiring different from the original bonding target due to the reflow process. In this case, an unintended current path may be formed and an electrical short circuit may occur.

Japanese Unexamined Patent Publication No. 2014-87938

This disclosure was conceived under the above-mentioned circumstances, and includes an IC chip mounting structure suitable for preventing defects during flip chip mounting, and a thermal print head having the mounting structure. The main issue is to provide.

The mounting structure of the IC chip provided by the first aspect of the present disclosure comprises a substrate having a main surface facing one side in the thickness direction, and a support member having a wiring layer arranged on the main surface. A mounting structure comprising an IC chip having a mounting surface and a plurality of conductive bonding materials arranged on the mounting surface, wherein the IC chip is flip-chip mounted on the support member, and the support member is a support member. It is arranged corresponding to the plurality of conductive bonding materials and has a plurality of pad portions including at least two concave pad portions, and the concave pad portions are viewed from the bottom surface and the thickness direction of the base material. It has an inner wall surface facing the bottom surface, and the inner wall surface is composed of the wiring layer.

The thermal printhead provided by the second aspect of the present disclosure has the mounting structure of the IC chip according to the first aspect of the present disclosure, is arranged on the main surface, and arranged in the main scanning direction. A resistor layer including a plurality of heat generating portions is provided, the wiring layer is conductive to the resistor layer, and the IC chip controls a current flowing through each of the heat generating portions.

The method for manufacturing a thermal printhead provided by the third aspect of the present disclosure comprises a step of preparing a base material and the base material and the wiring layer by forming a wiring layer on the base material. A step of forming a support member, a step of forming a resistor layer that overlaps a part of the wiring layer in the thickness direction of the base material on the support member, and a plurality of conductive bonding materials are mounted. The step of flip-chip mounting the IC chip arranged on the surface to the base material is provided, and the step of forming the support member includes at least two concave pad portions and corresponds to the plurality of conductive bonding materials. A plurality of pad portions are formed, and the concave pad portion has a bottom surface and an inner wall surface facing the bottom surface when viewed in the thickness direction of the base material.

According to the present disclosure, the misalignment of the IC chip at the time of mounting the flip chip is improved, and it is suitable for preventing the trouble caused by the misalignment.

Other features and advantages of the present disclosure will be more apparent by the detailed description given below with reference to the accompanying drawings.

It is a top view which shows the thermal print head which concerns on 1st Embodiment of this disclosure. FIG. 3 is a schematic cross-sectional view taken along the line II-II of FIG. FIG. 3 is an enlarged plan view of a main part of the thermal print head shown in FIG. 1. It is a partially enlarged view of FIG. FIG. 3 is a partially enlarged cross-sectional view taken along the line VV of FIG. It is a partially enlarged view of FIG. FIG. 3 is an enlarged plan view of a main part of the thermal print head shown in FIG. 1. FIG. 7 is a cross-sectional view taken along the line VIII-VIII of FIG. It is sectional drawing which shows one process of an example of the manufacturing method of the thermal print head shown in FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is sectional drawing which shows the process which follows FIG. It is an enlarged sectional view for demonstrating the process shown in FIG. It is the same cross-sectional view as FIG. 17 which shows the state after the reflow process. It is an enlarged sectional view for demonstrating the process shown in FIG. It is the same cross-sectional view as FIG. 19 which shows the state after the reflow process. FIG. 3 is an enlarged plan view of a main part similar to FIG. 7 showing a first modification of the thermal print head shown in FIG. 1. FIG. 3 is an enlarged plan view of a main part similar to FIG. 7 showing a second modification of the thermal print head shown in FIG. 1. FIG. 2 is an enlarged cross-sectional view taken along the line XXIII-XXIII of FIG. 22. FIG. 2 is an enlarged cross-sectional view taken along the line XXIV-XXIV of FIG. 22. It is the same cross-sectional view as FIG. 6 which shows the 3rd modification of the thermal print head shown in FIG. It is the same cross-sectional view as FIG. 6 which shows the 4th modification of the thermal print head shown in FIG. It is the same cross-sectional view as FIG. 6 which shows the 5th modification of the thermal print head shown in FIG. It is the same cross-sectional view as FIG. 4 which shows the thermal print head which concerns on 2nd Embodiment of this disclosure. FIG. 28 is a partially enlarged view. FIG. 28 is a cross-sectional view similar to FIG. 29 showing a modified example of the thermal print head shown in FIG. 28.

Hereinafter, preferred embodiments of the present disclosure will be specifically described with reference to the drawings.

In the present disclosure, "something A is formed on a certain thing B" and "something A is formed on a certain thing B" means "there is a certain thing A" unless otherwise specified. It includes "being formed directly on the object B" and "being formed on the object B by the object A while interposing another object between the object A and the object B". Similarly, "something A is placed on something B" and "something A is placed on something B" means "something A is placed on something B" unless otherwise specified. It includes "being placed directly on B" and "being placed on a certain thing B while having another thing intervening between a certain thing A and a certain thing B". Similarly, "a certain thing A is located on a certain thing B" means "a certain thing A is in contact with a certain thing B and a certain thing A is located on a certain thing B" unless otherwise specified. "What you are doing" and "The thing A is located on the thing B while another thing is intervening between the thing A and the thing B". In addition, "something A overlaps with a certain thing B when viewed in a certain direction" means "overlaps a certain thing A with all of a certain thing B" and "a certain thing A overlaps with all of a certain thing B" unless otherwise specified. "Overlapping a part of a certain object B" is included.

<First Embodiment>
1 to 8 show a thermal print head according to the first embodiment of the present disclosure. The thermal print head A1 of the present embodiment includes a substrate 1, a glaze layer 2, a wiring layer 3, a resistor layer 4, a protective layer 5, an IC chip 6, a protective resin 71, and a connector 72. The thermal print head A1 includes a mounting structure in which the IC chip 6 is flip-chip mounted (the mounting structure of the IC chip according to the present disclosure). The thermal print head A1 is incorporated in a printer that prints on a print medium 82 conveyed by a platen roller 81 (see FIG. 2). Examples of such a print medium 82 include a bar code sheet and a thermal paper for producing a receipt.

FIG. 1 is a plan view showing the thermal print head A1. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. FIG. 3 is an enlarged plan view of a main part showing the thermal print head A1. FIG. 4 is an enlarged cross-sectional view of a part of FIG. 2. FIG. 5 is a partially enlarged cross-sectional view taken along the line VV of FIG. FIG. 6 is an enlarged cross-sectional view of a part of FIG. FIG. 7 is an enlarged plan view of a main part of the thermal print head A1 and represents a part of the IC chip. FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG. For convenience of understanding, the protective layer 5 is omitted in FIGS. 1 and 3. In FIG. 4, the connector 73 is omitted. In FIG. 7, the protective resin 71 is omitted. Further, in these figures, the longitudinal direction (main scanning direction) of the substrate 1 is defined as the x direction, the lateral direction (sub-scanning direction) is defined as the y direction, and the thickness direction is defined as the z direction. In the y direction, the lower part of FIGS. 1 and 3 (left side of FIGS. 2 and 4) is defined as the “upstream” to which the print medium is sent, and the upper part of FIGS. 1 and 3 (FIGS. 2 and 4). The right side of) is the "downstream" where the print medium is discharged. Further, regarding the z direction, the upper side of FIGS. 2 and 4 (the direction indicated by the arrow indicating the direction z) is referred to as “upward”, and the opposite direction is referred to as “downward”. The same applies to the following figure.

The substrate 1 is made of a ceramic such as Al ₂ O ₃ and has a thickness of, for example, about 0.6 to 1.0 mm. As shown in FIG. 1, the substrate 1 has a long rectangular shape extending long in the x direction. The glaze layer 2, the wiring layer 3, the resistor layer 4, the protective layer 5, the IC chip 6, and the protective resin 71 are arranged on the substrate 1. The connector 72 is for connecting to an external device, and is provided, for example, at the lower end of FIG. 1 in the y direction of the substrate 1.

The glaze layer 2 is arranged on the substrate 1 and is made of a glass material such as amorphous glass. The glaze layer 2 of the present embodiment is formed so as to have a certain thickness, and has a substantially flat main surface 21 facing upward in the z direction. The thickness of the glaze layer 2 is, for example, 50 to 200 μm.

The thermal print head A1 has a so-called thick film type configuration, and is manufactured by utilizing thick film printing. The glaze layer 2 is formed by printing a thick film of a glass paste on a substrate 1 and then firing the glass paste. In other words, the glaze layer 2 is formed by a thick film forming technique.

The wiring layer 3 is for forming a path for energizing the resistor layer 4, and is arranged on the main surface 21 of the glaze layer 2. The wiring layer 3 is formed so as to have a specific resistance value smaller than the specific resistance value of the resistor layer 4. The wiring layer 3 of the present embodiment has a first metal portion 3a and a second metal portion 3b made of a metal different from the first metal portion 3a. Specifically, the first metal portion 3a is made of a conductor containing gold (Au) as a main component, and the second metal portion 3b is made of a conductor containing silver (Ag) as a main component. The first metal portion 3a is made of registered Au to which, for example, rhodium, vanadium, bismuth, silicon or the like is added as an additive element. From the viewpoint of conductivity, it is possible to obtain excellent properties by using only the first metal portion 3a, but considering the cost problem, it is desirable to use the cheaper second metal portion 3b together. ..

As shown in FIGS. 3 to 8 and the like, the wiring layer 3 has a common electrode 33, a plurality of individual electrodes 34, a plurality of signal wiring portions 37, and a plurality of pad portions 38.

The common electrode 33 has a common portion 331 and a plurality of common electrode strips 332. Specifically, the common portion 331 is arranged on the downstream side in the y direction with respect to the resistor layer 4, and extends along the x direction. Each of the plurality of common electrode band-shaped portions 332 extends upstream from the common portion 331 in the y direction, and is arranged at equal pitches in the x direction.

The plurality of individual electrodes 34 are for partially energizing the resistor layer 4, and are portions having opposite polarities with respect to the common electrode 33. The individual electrode 34 extends from the resistor layer 4 toward the IC chip 6. The plurality of individual electrodes 34 are arranged in the x direction, and each has an individual electrode band-shaped portion 35 and a connecting portion 36.

Each individual electrode band-shaped portion 35 is a band-shaped portion extending in the y direction, and is located between two adjacent common electrode band-shaped portions 332 of the common electrode 33. The connecting portion 36 is a portion extending from the individual electrode band-shaped portion 35 toward the IC chip 6, and most of the connecting portion 36 has a portion along the y direction and a portion inclined with respect to the y direction. The connecting portions 36 are arranged on the upstream side in the y direction at relatively narrow intervals in the x direction. The distance between adjacent connecting portions 36 on the upstream side in the y direction is, for example, about 20 μm or less. As shown in FIG. 7, the end portion on the upstream side in the y direction of each connecting portion 36 overlaps with the IC chip 6 when viewed in the z direction.

The plurality of signal wiring units 37 form a wiring pattern connected to the connector 72 and the IC chip 6. As shown in FIG. 7, the plurality of signal wiring portions 37 are arranged in the x direction and each extend in the y direction in the vicinity of the IC chip 6. The downstream end of each signal wiring portion 37 in the y direction overlaps with the IC chip 6 when viewed in the z direction. The IC chip 6 used for the thermal print head A1 usually has a long rectangular planar shape (see FIG. 1). The long side of the IC chip 6 is along the x direction (main scanning direction) in which the resistor layer 4 extends.

In the present embodiment, as shown in FIGS. 3 and 5, the first metal portion 3a includes the common portion 331 of the common electrode 33, the plurality of common electrode band-shaped portions 332, and the individual electrode strip-shaped portions 35 of the plurality of individual electrodes 34. And, including. The first metal portion 3a is connected to the resistor layer 4 (a plurality of heat generating portions 41 described later). The second metal portion 3b is arranged in a region on the upstream side in the y direction with respect to the first metal portion 3a. The second metal portion 3b includes a connecting portion 36 in the plurality of individual electrodes 34 and a plurality of signal wiring portions 37.

As shown in FIGS. 6 and 8, the plurality of pad portions 38 are portions connected to the IC chip 6 mounted on the flip chip via the plurality of conductive bonding materials 62. A plurality of pad portions 38 are arranged in the x direction and the y direction. As shown in FIG. 7, the plurality of pad portions 38 are the end portion on the upstream side in the y direction of any of the plurality of connecting portions 36 (individual electrodes 34), or the downstream side in the y direction of any of the plurality of signal wiring portions 37. It is connected to the end. In the present embodiment, the plurality of pad portions 38 are formed in two rows in the y direction.

A plurality of conductive bonding materials 62 are arranged on the mounting surface 61 (the surface facing the substrate 1) of the IC chip 6. The conductive bonding material 62 is, for example, a solder bump. The plurality of pad portions 38 are arranged corresponding to the plurality of conductive bonding materials 62.

In the x direction, the pad portions 38 are arranged in large numbers corresponding to the plurality of connecting portions 36 (individual electrodes 34) and the plurality of signal wiring portions 37. The distance L1 between the adjacent pad portions 38 in the x direction is relatively small, for example, about 10 to 20 μm. On the other hand, the distance L2 between the pad portions 38 in the y direction is relatively large, for example, about 100 to 200 μm.

The plurality of pad portions 38 includes at least two concave pad portions 381. In the present embodiment, all of the plurality of pad portions 38 are concave pad portions 381. The term pad portion 38 includes both a concave pad portion 381 and a non-concave pad portion (a pad portion whose entire range is flat when viewed along the thickness direction).

In the present embodiment, the wiring layer 3 (second metal portion 3b) includes the first layer 31 and the second layer 32, and the concave pad portion 381 is formed by the first layer 31 and the second layer 32. It is composed. Specifically, the first layer 31 is arranged on the main surface 21 of the glaze layer 2. The first layer 31 has a flat surface 311 facing upwards. The thickness of the first layer 31 is, for example, about 2 to 5 μm. The second layer 32 is arranged on the surface 311 of the first layer 31. The second layer 32 is arranged on a part of the first layer 31. The second layer 32 is formed in a plurality of regions corresponding to the plurality of pad portions 38 (concave pad portions 381). Each region of the second layer 32 has a rectangular annular shape when viewed in the z direction, and has a top surface 321. The top surface 321 is the upper end surface in the z direction of the second layer 32. The thickness of the second layer 32 (dimensions in the z direction from the surface 311 to the top surface 321) is, for example, about 2 to 5 μm.

In the present embodiment, the concave pad portion 381 has a bottom surface 312 and an inner wall surface 322. The bottom surface 312 is composed of a region of the surface 311 of the first layer 31 surrounded by the second layer 32 when viewed in the z direction. The inner wall surface 322 is composed of a surface of each region of the second layer 32 facing the bottom surface 312 when viewed in the z direction. In the present embodiment, the inner wall surface 322 is a rectangular ring shape surrounding the bottom surface 312 when viewed in the z direction. Then, as shown in FIGS. 6 and 8, each of the plurality of conductive bonding materials 62 is housed in the inner space of the concave pad portion 381, and the concave pad portion 381 (the first wiring layer 3) is accommodated. It is bonded to the layer 31 to the second layer 32).

The resistor layer 4 is made of, for example, ruthenium oxide having a resistivity higher than that of the material constituting the wiring layer 3, and is formed in a band shape extending in the x direction. As shown in FIG. 3, the resistor layer 4 intersects the plurality of common electrode band-shaped portions 332 of the common electrode 33 and the individual electrode strip-shaped portions 35 of the plurality of individual electrodes 34. Further, the resistor layer 4 is laminated on the side opposite to the substrate 1 with respect to the plurality of common electrode band-shaped portions 332 of the common electrode 33 and the individual electrode strip-shaped portions 35 of the plurality of individual electrodes 34. The portion of the resistor layer 4 sandwiched between the common electrode strips 332 and the individual electrode strips 35 is a heat generating portion 41 that generates heat when partially energized by the wiring layer 3. One print dot is formed by the heat generated by the two heat generating portions 41 adjacent to each other with the one individual electrode band-shaped portion 35 interposed therebetween. The thickness of the resistor layer 4 is, for example, about 3 to 10 μm.

The protective layer 5 is for protecting the wiring layer 3 and the resistor layer 4. The protective layer 5 is made of, for example, amorphous glass. However, the protective layer 5 exposes a region including a plurality of concave pad portions 381 (pad portions 38).

The IC chip 6 functions to partially generate heat in the resistor layer 4 by selectively energizing a plurality of individual electrodes 34. As shown in FIGS. 1 and 4, the IC chip 6 is arranged on the upstream side in the y direction with respect to the resistor layer 4 (plural heat generating portions 41). In this embodiment, a plurality of IC chips 6 are arranged on the glaze layer 2 by flip-chip mounting. As described above, a plurality of conductive bonding materials 62 are provided on the mounting surface 61 of the IC chip 6, and these conductive bonding materials 62 are bonded to the plurality of concave pad portions 381. As shown in FIGS. 2, 4 and 6, the IC chip 6 is covered with the protective resin 71. The protective resin 71 is made of, for example, a black soft resin. Further, the IC chip 6 and the connector 72 are connected by the plurality of signal wiring portions 37. A print signal transmitted from the outside, a control signal, and a voltage supplied to a plurality of heat generating units 41 are input to the IC chip 6 via the connector 72. The plurality of heat generating units 41 are selectively heated by being individually energized according to the print signal and the control signal.

In the above configuration, the substrate 1 and the glaze layer 2 arranged on the substrate 1 constitute the "base material" in the present disclosure. Further, the substrate 1 and the glaze layer 2 (base material), and the wiring layer 3 arranged on the main surface 21 of the glaze layer 2 constitute the "support member" in the present disclosure.

Next, an example of how to use the thermal print head A1 will be briefly described.

The thermal print head A1 is used in a state of being incorporated in the printer. As shown in FIG. 2, in the printer, each heat generating portion 41 of the thermal print head A1 faces the platen roller 81. When the printer is used, the platen roller 81 rotates, so that the printing medium 82 such as thermal paper is fed between the platen roller 81 and each heat generating portion 41 at a constant speed along the y direction. The print medium 82 is pressed against the portion of the protective layer 5 that covers each heat generating portion 41 by the platen roller 81. On the other hand, a potential is selectively applied to each individual electrode 34 shown in FIG. 3 by the IC chip 6. As a result, a voltage is applied between the common electrode 33 and each of the plurality of individual electrodes 34. Then, a current selectively flows through the plurality of heat generating portions 41, and heat is generated. Then, the heat generated in each heat generating portion 41 is transmitted to the print medium 82 via the protective layer 5. Then, a plurality of dots are printed in the line region extending linearly in the x direction on the print medium 82. Further, the heat generated in each heat generating portion 41 is also transmitted to the glaze layer 2 and stored in the glaze layer 2.

Next, an example of a method for manufacturing the thermal print head A1 will be described below with reference to FIGS. 9 to 20. 9 to 16 are cross-sectional views showing one step of the manufacturing method of the thermal print head A1, and correspond to a partially enlarged view of the cross section shown in FIG.

First, as shown in FIG. 9, the substrate 1 is prepared. The substrate 1 is a plate material made of ceramic such as Al ₂ O ₃ and has a predetermined thickness.

Next, as shown in FIG. 10, the glaze layer 2 is formed. The glaze layer 2 is formed by printing a thick film of glass paste on the substrate 1 and then firing the glass paste. The glaze layer 2 covers the entire surface of the substrate 1. The glaze layer 2 has a main surface 21. The main surface 21 is substantially flat and faces upward in the z direction. The steps shown in FIGS. 9 and 10 correspond to the "step of preparing the base material" of the present disclosure.

Next, as shown in FIG. 11, the first metal portion 3a of the wiring layer 3 is formed. Here, first, a thick film of the resinate Au paste is printed on the main surface 21 of the glaze layer 2, and then the paste is fired to form a metal film. Next, the metal film is patterned by, for example, etching to form a first metal portion 3a having a predetermined shape.

Next, as shown in FIG. 12, the first layer 31 of the wiring layer 3 (second metal portion 3b) is formed (first layer forming step). Here, first, a negative-type photosensitive Ag paste is placed on the main surface 21 of the glaze layer 2 by screen printing and dried. The photosensitive Ag paste on the main surface 21 is then partially exposed to UV light, for example using a photomask. The exposed portion of the photosensitive Ag paste is the portion to be the first layer 31. Then, a developer is used to remove the portion of the photosensitive Ag paste other than the exposed portion. Next, the photosensitive Ag paste remaining on the main surface 21 is fired to form a film. As a result, the first layer 31 is formed. The photosensitive Ag paste used for forming the first layer 31 corresponds to the "first photosensitive metal paste" referred to in the present disclosure.

Next, as shown in FIG. 13, the second layer 32 of the wiring layer 3 (second metal portion 3b) is formed. Here, first, a negative-type photosensitive Ag paste is placed on the surface 311 of the first layer 31 by screen printing and dried. Then, for example, using a photomask, the photosensitive Ag paste on the first layer 31 is partially exposed to ultraviolet light. The exposed portion of the photosensitive Ag paste is the portion to be the second layer 32. Then, a developer is used to remove the portion of the photosensitive Ag paste other than the exposed portion. Next, the photosensitive Ag paste remaining on the first layer 31 is fired to form a film. As a result, the second layer 32 is formed. Here, the second layer 32 is formed in a plurality of regions corresponding to the ends of the plurality of connecting portions 36 and the ends of the plurality of signal wiring portions 37, and each region of the second layer 32 is formed in the z direction. It is formed in a rectangular ring shape. Due to the formation of the second layer 32, each region of the surface 311 of the first layer 31 surrounded by the second layer 32 when viewed in the z direction becomes the bottom surface 312. Further, in each region of the second layer 32, the surface facing the bottom surface 312 when viewed in the z direction is the inner wall surface 322. In this way, in this step, a plurality of concave pad portions 381, each having a bottom surface 312 and an inner wall surface 322, are formed. The photosensitive Ag paste used for forming the second layer 32 corresponds to the "second photosensitive metal paste" referred to in the present disclosure.

Then, as shown in FIG. 14, the resistor layer 4 is formed. The resistor layer 4 is formed by printing a thick film of a resistor paste containing a resistor such as ruthenium oxide and firing it.

Then, as shown in FIG. 15, the protective layer 5 is formed. The protective layer 5 is formed by, for example, applying a glass paste to the area where the protective layer 5 is to be formed by thick film printing and firing the protective layer 5. After that, the substrate 1 is cut in a grid pattern along the x-direction and the y-direction, and divided into a plurality of pieces. The step of dividing into the individual pieces is performed, for example, by laser irradiation. Each piece corresponds to the substrate 1 of the thermal print head A1.

Next, as shown in FIG. 16, the IC chip 6 is mounted on the glaze layer 2 by flip-chip mounting. Here, for example, flux (not shown) is applied to a plurality of conductive bonding materials 62, and the conductive bonding materials 62 are arranged on a plurality of electrodes (not shown) formed on the mounting surface 61 of the IC chip 6. I will do it. As another method, after applying flux (not shown) to a plurality of electrodes (not shown), each conductive bonding material 62 may be arranged on each electrode. When the IC chip 6 is mounted, the IC chip 6 is placed on the wiring layer 3 while aligning the plurality of conductive bonding materials 62 and the plurality of pad portions 38 (concave pad portion 381) by a mounter (not shown). , The plurality of conductive bonding materials 62 and the plurality of pad portions 38 (concave pad portions 381) are temporarily attached by the above flux. Next, the plurality of conductive bonding materials 62 are melted by the reflow treatment, and the plurality of pad portions 38 (concave pad portions 381) and the plurality of conductive bonding materials 62 are bonded to each other.

Before the reflow process, when the IC chip 6 is placed on the wiring layer 3 as described above and the plurality of conductive bonding materials 62 and the plurality of pad portions 38 (concave pad portions 381) are temporarily attached, the IC chips 6 are temporarily attached. The mounting position of the IC chip 6 may shift due to mechanical variation. In this case, for example, as shown in FIGS. 17 and 19, the positions of the plurality of conductive bonding members 62 are displaced with respect to the plurality of pad portions 38 (concave pad portions 381). FIG. 17 shows an aspect of the misalignment of the plurality of conductive bonding materials 62 (IC chip 6) in the y direction, and FIG. 19 shows the misalignment of the plurality of conductive bonding materials 62 (IC chip 6) in the x direction. The aspect is shown.

In the embodiment shown in FIGS. 17 and 19, as the conductive bonding material 62 melts during the reflow process, the conductive bonding material 62 has a concave shape (bottom surface 312 and inner wall surface 322) of the concave pad portion 381. You will be guided to fall into the enclosed space). As a result, as shown in FIGS. 18 and 20, the conductive bonding material 62 is housed in the concave pad portion 381, and the misalignment of the conductive bonding material 62 and the IC chip 6 is improved.

After mounting the flip chip of the IC chip 6, the thermal print head A1 can be obtained by forming the protective resin 71 and attaching the connector 72.

Next, the operation of the thermal print head A1 will be described.

A plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 mounted with flip chips. The wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 include at least two concave pad portions 381. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 312 and the inner wall surface 322 facing the bottom surface 312). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The wiring layer 3 includes a first layer 31 and a second layer 32. The first layer 31 is arranged on the main surface 21 of the glaze layer 2, and the second layer 32 is arranged on a part of the first layer 31. The bottom surface 312 of the concave pad portion 381 is composed of the first layer 31, and the inner wall surface 322 of the concave pad portion 381 is composed of the second layer 32. According to such a configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the bottom surface 312 and the inner wall surface 322 (first layer 31 and second layer 32), so that the bonding area is large. Therefore, it is suitable for increasing the bonding strength of the conductive bonding material 62. Further, in the present embodiment, since the bonding area between the conductive bonding material 62 and the wiring layer 3 (first layer 31 and the second layer 32) becomes large, the conductive bonding material 62 and the wiring layer 3 are conductively bonded. Improves reliability.

In the present embodiment, the inner wall surface 322 constituting the concave pad portion 381 forms a rectangular annular shape (annular shape) surrounding the bottom surface 312 when viewed in the z direction. According to such a configuration, even if the position shift occurs in both the x-direction and the y-direction when the IC chip 6 is mounted, both the x-direction and the y-direction of the conductive bonding material 62 and the IC chip 6 are provided. Misalignment is improved.

In the present embodiment, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

<Modified example of the first embodiment>
21 to 24 show a modification of the thermal print head A1 according to the first embodiment described above. In the drawings after FIG. 21, the same or similar elements as the thermal printhead A1 of the above embodiment are designated by the same reference numerals as those of the above embodiment, and the description thereof will be omitted as appropriate.

<First modification of the first embodiment>
FIG. 21 shows a first modification of the first embodiment. In the thermal print head A11 of the present modification, a part of the plurality of pad portions 38 is configured as the concave pad portion 381, and all of the plurality of pad portions 38 are configured as the concave pad portion 381. Is different from.

In the thermal print head A11 illustrated in FIG. 21, a plurality of pad portions 38 are arranged in each of the x direction and the y direction, and are located at the four corners of the pad portions 38 in the x direction and the y direction. Is configured as a concave pad portion 381. The specific configuration of each concave pad portion 381 is the same as that of the thermal print head A1. Therefore, each region of the second layer 32 constituting the concave pad portion 381 has a rectangular annular shape when viewed in the z direction. The concave pad portion 381 has a bottom surface 312 composed of a first layer 31 and an inner wall surface 322 composed of a second layer 32 and forming a rectangular annular shape surrounding the bottom surface 312 when viewed in the z direction. In this modification, the configuration other than the arrangement of the concave pad portion 381 is the same as that of the thermal print head A1 described above.

Although detailed illustration description is omitted, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in this modification, the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of the plurality of pad portions 38 are (4). Includes the concave pad portion 381 of. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 312 and the inner wall surface 322 facing the bottom surface 312). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip. Instead of the four concave pad portions 381 shown in FIG. 21, one concave pad portion 381 may be arranged at each of the two corners along the diagonal direction of the IC chip 6. In this case, two concave pad portions 381 are arranged on one IC chip 6. In addition to the two concave pad portions 381 described above, three concave pad portions 381 including the concave pad portion 381 located at another corner may be used. In this case as well, it is possible to prevent problems caused by misalignment when the IC chip 6 is mounted on the flip chip.

The wiring layer 3 includes a first layer 31 and a second layer 32. The first layer 31 is arranged on the main surface 21 of the glaze layer 2, and the second layer 32 is arranged on a part of the first layer 31. The bottom surface 312 of the concave pad portion 381 is composed of the first layer 31, and the inner wall surface 322 of the concave pad portion 381 is composed of the second layer 32. According to such a configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the bottom surface 312 and the inner wall surface 322 (first layer 31 and second layer 32), so that the bonding area is large. Therefore, it is suitable for increasing the bonding strength of the conductive bonding material 62. Further, in the present embodiment, since the bonding area between the conductive bonding material 62 and the wiring layer 3 (first layer 31 and the second layer 32) becomes large, the conductive bonding material 62 and the wiring layer 3 are conductively bonded. Improves reliability.

In this modification, of the plurality of pad portions 38, those located at the four corners in the x direction and the y direction are configured as the concave pad portion 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be appropriately obtained.

<Second variant of the first embodiment>
22 to 24 show a second modification of the first embodiment. The thermal print head A12 of this modification is different from the thermal print head A1 of the above embodiment in the specific configuration of the concave pad portion 381.

In the thermal print head A12 exemplified in FIGS. 22 to 24, the shape of each region of the second layer 32 constituting the concave pad portion 381 is different from that of the thermal print head A1. Each region of the second layer 32 constituting the concave pad portion 381 is composed of a pair of upright walls separated from each other in the x direction and each extending in the y direction. Of the surface 311 of the first layer 31, the portion sandwiched between the pair of upright walls when viewed in the z direction is the bottom surface 312 of the concave pad portion 381. The pair of upright walls have a pair of inner wall surfaces 322 facing each other, and the pair of inner wall surfaces 322 face one side in the x direction and the other side in the x direction corresponding to the longitudinal direction of the IC chip 6. ..

In the thermal print head A12 of this modification, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in this modification, the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 have a plurality of concave pad portions. 381 is included. According to such a configuration, even if a slight positional deviation occurs in the x direction when the IC chip 6 is mounted, when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). , The conductive bonding material 62 is guided to fall into the concave pad portion 381 (the space surrounded by the bottom surface 312 and the inner wall surface 322 facing the bottom surface 312). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The wiring layer 3 includes a first layer 31 and a second layer 32. The first layer 31 is arranged on the main surface 21 of the glaze layer 2, and the second layer 32 is arranged on a part of the first layer 31. The bottom surface 312 of the concave pad portion 381 is composed of the first layer 31, and the inner wall surface 322 of the concave pad portion 381 is composed of the second layer 32. According to such a configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the bottom surface 312 and the inner wall surface 322 (first layer 31 and second layer 32), so that the bonding area is large. Therefore, it is suitable for increasing the bonding strength of the conductive bonding material 62. Further, in the present embodiment, since the bonding area between the conductive bonding material 62 and the wiring layer 3 (first layer 31 and the second layer 32) becomes large, the conductive bonding material 62 and the wiring layer 3 are conductively bonded. Improves reliability.

In this modification, the inner wall surface 322 is composed of the second layer 32. Further, the concave pad portion 381 has a pair of inner wall surfaces 322 facing one side in the x direction and the other side in the x direction and facing each other. According to such a configuration, when the flip chip of the IC chip 6 is mounted, the positional deviation in the x direction corresponding to the longitudinal direction of the IC chip 6 can be appropriately improved. Further, the distance L1 between the adjacent pad portions 38 in the x direction is smaller than the distance L2 between the pad portions 38 in the y direction. In such a configuration, the effect of improving the misalignment of the IC chip 6 can be efficiently obtained while reducing the formation region of the second layer 32.

<Third variant of the first embodiment>
FIG. 25 shows a third modification of the first embodiment. In the thermal print head A13 of this modification, the wiring layer 3 does not have the second layer 32 and is composed of a single layer, and accordingly, the configuration of the concave pad portion 381 is different from that of the thermal print head A1.

In the thermal print head A13 exemplified in FIG. 25, all of the plurality of pad portions 38 are concave pad portions 381, and each concave pad portion 381 has a configuration in which the wiring layer 3 is partially recessed from the surface 311. .. The concave pad portion 381 has a bottom surface 313 and an inner wall surface 314. The bottom surface 313 is composed of a portion of the wiring layer 3 having a relatively small thickness. The inner wall surface 322 forms an annular shape surrounding the bottom surface 313 when viewed in the z direction. The wiring layer 3 having such a concave pad portion 381 is formed on the main surface 21 of the glaze layer 2, and is made of, for example, a conductor containing Ag as a main component. In the formation of the wiring layer 3, a metal film is formed by first printing a thick film of Ag paste on the main surface 21 and then firing the paste. Next, the metal film is patterned by using a technique such as etching to form a wiring layer 3 having a plurality of individual electrodes 34 and a plurality of signal wiring portions 37 and the like. Next, the wiring layer 3 is patterned by using a technique such as half etching to form a concave pad portion 381 having a bottom surface 313 and an inner wall surface 314.

In the thermal print head A13 of this modification, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in this modification, the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 have a plurality of concave pad portions. 381 is included. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 313 and the inner wall surface 314 facing the bottom surface 313). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The concave pad portion 381 is formed in the wiring layer 3 and has a bottom surface 313 and an inner wall surface 314. The bottom surface 313 is composed of a portion of the wiring layer 3 having a relatively small thickness, and the inner wall surface 322 forms an annular shape surrounding the bottom surface 313 when viewed in the z direction. According to this configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the bottom surface 312 and the inner wall surface 322, so that the bonding area with the wiring layer 3 becomes large, and the conductive bonding material becomes large. Suitable for increasing the bonding strength of 62. Further, according to the configuration in which the inner wall surface 322 forms an annular shape surrounding the bottom surface 313 when viewed in the z direction, even if the position shift occurs in both the x direction and the y direction when the IC chip 6 is mounted, the conductive bonding is performed. The misalignment of the material 62 and the IC chip 6 in both the x-direction and the y-direction is improved.

In this modification, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

<Fourth modification of the first embodiment>
FIG. 26 shows a fourth modification of the first embodiment. In the thermal print head A14 of this modification, the wiring layer 3 is composed of a single layer, and the configuration of the concave pad portion 381 is different from that of the thermal print head A1.

In the thermal print head A14 illustrated in FIG. 26, all of the plurality of pad portions 38 are concave pad portions 381, and each concave pad portion 381 has a configuration in which the wiring layer 3 partially penetrates to the glaze layer 2. There is. The concave pad portion 381 has a bottom surface 211 and an inner wall surface 315. The bottom surface 211 is composed of a portion exposed from the wiring layer 3 on the main surface 21 of the glaze layer 2. The inner wall surface 315 has an annular shape surrounding the bottom surface 211 when viewed in the z direction, and is composed of an inner surface of a penetrating portion of the wiring layer 3. In this modification, the concave pad portion 381 is composed of a glaze layer 2 and a wiring layer 3.

The wiring layer 3 in this modification is formed on the main surface 21 of the glaze layer 2, and is made of, for example, a conductor containing Ag as a main component. In the formation of the wiring layer 3, a metal film is formed by first printing a thick film of Ag paste on the main surface 21 and then firing the paste. Next, by patterning the metal film using a technique such as etching, a wiring layer 3 having a plurality of individual electrodes 34 and a plurality of signal wiring portions 37 and the like is formed, and together with this, each of them is formed. A plurality of concave pad portions 381 having a bottom surface 211 and an inner wall surface 315 are formed.

In the thermal print head A14 of this modification, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in this modification, the glaze layer 2 or the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 are plurality. Includes the concave pad portion 381 of. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 211 and the inner wall surface 315 facing the bottom surface 211). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The bottom surface 211 of the concave pad portion 381 is composed of a portion exposed from the wiring layer 3 on the main surface 21 of the glaze layer 2. The inner wall surface 315 is composed of a wiring layer 3, and is an annular shape surrounding the bottom surface 211 when viewed in the z direction. According to such a configuration, even if the position shift occurs in both the x-direction and the y-direction when the IC chip 6 is mounted, both the x-direction and the y-direction of the conductive bonding material 62 and the IC chip 6 are provided. Misalignment is improved.

In this modification, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

<Fifth variant of the first embodiment>
FIG. 27 shows a fifth modification of the first embodiment. In the thermal print head A15 of this modification, the wiring layer 3 is composed of a single layer, and the configuration of the concave pad portion 381 is different from that of the thermal print head A1.

In the thermal print head A15 illustrated in FIG. 27, all of the plurality of pad portions 38 are concave pad portions 381. Each concave pad portion 381 is configured by a combination of a configuration in which the surface 311 is partially recessed and a configuration in which the wiring layer 3 partially penetrates to the glaze layer 2. The concave pad portion 381 has a bottom surface 212, an intermediate surface 316, an inner wall surface 317, and an inner wall surface 318. The bottom surface 212 is composed of a portion exposed from the wiring layer 3 on the main surface 21 of the glaze layer 2. The inner wall surface 318 has an annular shape surrounding the bottom surface 212 when viewed in the z direction, and is composed of an inner surface of a penetrating portion of the wiring layer 3. The intermediate surface 316 is composed of a portion of the wiring layer 3 having a relatively small thickness. The inner wall surface 317 forms an annular shape surrounding the bottom surface 212 and the intermediate surface 316 when viewed in the z direction. In this modification, the concave pad portion 381 is composed of a glaze layer 2 and a wiring layer 3.

The wiring layer 3 in this modification is formed on the main surface 21 of the glaze layer 2, and is made of, for example, a conductor containing Ag as a main component. In the formation of the wiring layer 3, a metal film is formed by first printing a thick film of Ag paste on the main surface 21 and then firing the paste. Next, the metal film is patterned by using a technique such as etching to form a wiring layer 3 having a plurality of individual electrodes 34 and a plurality of signal wiring portions 37 and the like. Next, the wiring layer 3 is patterned using a technique such as half etching to form the intermediate surface 316 and the inner wall surface 317. Next, the wiring layer 3 is patterned using a technique such as etching to form a plurality of concave pad portions 381 each having a bottom surface 212, an intermediate surface 316, an inner wall surface 317, and an inner wall surface 318.

In the thermal print head A15 of this modification, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in this modification, the glaze layer 2 or the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 are plurality. Includes the concave pad portion 381 of. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 212 and the inner wall surfaces 317 and 318 facing the bottom surface 212). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The bottom surface 211 of the concave pad portion 381 is composed of a portion exposed from the wiring layer 3 on the main surface 21 of the glaze layer 2. The inner wall surface 317 is composed of a wiring layer 3, and is an annular shape surrounding the bottom surface 211 when viewed in the z direction. According to such a configuration, even if the position shift occurs in both the x-direction and the y-direction when the IC chip 6 is mounted, both the x-direction and the y-direction of the conductive bonding material 62 and the IC chip 6 are provided. Misalignment is improved.

The inner wall surface 318 forms an annular shape surrounding the bottom surface 212 when viewed in the z direction. The intermediate surface 316 is composed of a portion of the wiring layer 3 having a relatively small thickness, and the inner wall surface 317 forms an annular shape surrounding the bottom surface 212 and the intermediate surface 316 when viewed in the z direction. According to such a configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the inner wall surface 318, the intermediate surface 316, and the inner wall surface 317, so that the bonding area with the wiring layer 3 is large. Therefore, it is suitable for increasing the bonding strength of the conductive bonding material 62.

In this modification, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

<Second Embodiment>
28 and 29 show the thermal printhead according to the second embodiment of the present disclosure. The thermal print head A2 of the present embodiment is different from the thermal print head A11 of the above embodiment in the configuration of the glaze layer 2 and the configuration of the wiring layer 3. Along with this, the configuration of the concave pad portion 381 is different from that of the thermal print head A1.

In the thermal print head A11 shown in FIG. 28, the glaze layer 2 has a heater glaze portion 22 and a glass layer 23. The heater glaze portion 22 has a cross-sectional shape that is perpendicular to the x direction and bulges in the z direction, and has a z-direction visual band shape that extends long in the x direction. The glass layer 23 is formed adjacent to the heater glaze portion 22, and has a flat upper surface (main surface 231). The glass layer 23 overlaps a part of the heater glaze portion 22. The resistor layer 4 (plurality of heat generating portions 41) is arranged on the heater glaze portion 22 and overlaps with the heater glaze portion 22 in the z-direction view. When forming the glaze layer 2 having the heater glaze portion 22 and the glass layer 23, a thick film of the glass paste is printed on the substrate 1, and then firing is repeated a plurality of times.

As shown in FIG. 29, the wiring layer 3 has a base layer 3c and a plating layer 3d. The base layer 3c occupies most of the wiring layer 3, and the common electrode 33, the plurality of individual electrodes 34, and the plurality of signal wiring portions 37 are composed of the base layer 3c. Examples of the material constituting the base layer 3c include Al. The base layer 3c is formed by a thin film forming technique such as sputtering. The thickness of the base layer 3c is, for example, about 0.5 to 2.0 μm.

The plating layer 3d is provided to form a plurality of pad portions 38 (concave pad portions 381), and is laminated on a part of the base layer 3c. The plating layer 3d is laminated on the vicinity of the y-direction upstream end of the connecting portion 36 of the plurality of individual electrodes 34 and the vicinity of the y-direction downstream end of the plurality of signal wiring portions 37. The plating layer 3d is electroless plating made of, for example, Ni. The thickness of the plating layer 3d is, for example, about 1 to 2 μm.

In the thermal print head A2 of the present embodiment, all of the plurality of pad portions 38 are concave pad portions 381. Each concave pad portion 381 is configured such that the wiring layer 3 (base layer 3c and plating layer 3d) partially penetrates to the glaze layer 2 (glass layer 23). The concave pad portion 381 has a bottom surface 232 and an inner wall surface 303. The bottom surface 232 is composed of a portion exposed from the wiring layer 3 on the main surface 231 of the glass layer 23. The inner wall surface 303 has an annular shape surrounding the bottom surface 232 when viewed in the z direction, and is composed of an inner surface of a penetrating portion of the plating layer 3d. In this modification, the concave pad portion 381 is composed of a glaze layer 2 (glass layer 23) and a wiring layer 3 (plating layer 3d).

In the formation of the concave pad portion 381, the base layer 3c is patterned by using a technique such as etching to form a plurality of individual electrodes 34 and a plurality of signal wiring portions 37, and glass is formed from the surface 301 of the base layer 3c. A hole 302 that penetrates to the layer 23 is formed. As a result, a part of the main surface 231 of the glass layer 23 is exposed from the wiring layer 3 and becomes the bottom surface 232. Next, a plating layer 3d that covers a part of the surface 301 of the base layer 3c and the hole 302 is formed. As a result, in the plating layer 3d, the inner wall surface 303 facing the bottom surface 232 when viewed in the z direction is formed. In this way, a plurality of concave pad portions 381, each having a bottom surface 232 and an inner wall surface 303, are formed.

In the thermal print head A2 of the present embodiment, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in the present embodiment, the glaze layer 2 or the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 are plurality. Includes the concave pad portion 381 of. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 232 and the inner wall surface 303 facing the bottom surface 232). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The bottom surface 232 of the concave pad portion 381 is composed of a portion exposed from the wiring layer 3 on the main surface 231 of the glass layer 23 (glaze layer 2). The inner wall surface 315 is composed of a wiring layer 3, and is an annular shape surrounding the bottom surface 211 when viewed in the z direction. According to such a configuration, even if the position shift occurs in both the x-direction and the y-direction when the IC chip 6 is mounted, both the x-direction and the y-direction of the conductive bonding material 62 and the IC chip 6 are provided. Misalignment is improved.

In the present embodiment, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

<Modified example of the second embodiment>
FIG. 30 shows a modified example of the second embodiment. The thermal print head A21 of this modification is different from the thermal print head A2 of the above embodiment in the configurations of the base layer 3c and the plating layer 3d of the wiring layer 3. Along with this, the configuration of the concave pad portion 381 is different from that of the thermal print head A2.

In the thermal print head A21 of this modification, all of the plurality of pad portions 38 are concave pad portions 381. Each concave pad portion 381 has a configuration in which the wiring layer 3 is partially recessed. The concave pad portion 381 has a bottom surface 306 and an inner wall surface 307. The bottom surface 306 is composed of a portion of the wiring layer 3 having a relatively small thickness. The inner wall surface 307 forms an annular shape surrounding the bottom surface 306 when viewed in the z direction. The bottom surface 306 and the inner wall surface 307 are composed of a plating layer 3d (wiring layer 3).

In forming the concave pad portion 381, first, the base layer 3c is patterned by using a technique such as etching to form a plurality of individual electrodes 34 and a plurality of signal wiring portions 37. Next, a concave surface 304 recessed from the surface 301 of the base layer 3c is formed by using a technique such as half etching. Next, a plating layer 3d that covers a part of the surface 301 of the base layer 3c and the concave surface 304 is formed. As a result, in the plating layer 3d, a bottom surface 306 recessed from the top surface 305 and an inner wall surface 307 facing the bottom surface 306 when viewed in the z direction are formed. In this way, a plurality of concave pad portions 381, each having a bottom surface 306 and an inner wall surface 307, are formed.

In the thermal print head A21 of this modification, a plurality of conductive bonding materials 62 are arranged on the mounting surface 61 of the IC chip 6 on which the flip chip is mounted. Also in the present embodiment, the wiring layer 3 (support member) has a plurality of pad portions 38 arranged corresponding to the plurality of conductive bonding materials 62, and the plurality of pad portions 38 have a plurality of concave pad portions. 381 is included. According to such a configuration, even if a slight misalignment occurs when the IC chip 6 is mounted, the conductive bonding material 62 is conductive when the conductive bonding material 62 is bonded to the wiring layer 3 (support member) (during reflow processing). The joining material 62 is guided to fall into the concave pad portion 381 (a space surrounded by the bottom surface 306 and the inner wall surface 307 facing the bottom surface 306). This improves the misalignment of the conductive bonding material 62 and the IC chip 6, and is suitable for preventing defects caused by the misalignment when the IC chip 6 is mounted on the flip chip.

The concave pad portion 381 is formed on the plating layer 3d (wiring layer 3), and has a bottom surface 306 and an inner wall surface 307. The bottom surface 306 is composed of a portion of the wiring layer 3 having a relatively small thickness, and the inner wall surface 307 forms an annular shape surrounding the bottom surface 306 when viewed in the z direction. According to this configuration, the conductive bonding material 62 housed in the concave pad portion 381 is bonded across the bottom surface 306 and the inner wall surface 307, so that the bonding area with the wiring layer 3 becomes large, and the conductive bonding material becomes large. Suitable for increasing the bonding strength of 62. Further, according to the configuration in which the inner wall surface 307 forms an annular shape surrounding the bottom surface 306 when viewed in the z direction, even if the position shift occurs in both the x direction and the y direction when the IC chip 6 is mounted, the conductive bonding is performed. The misalignment of the material 62 and the IC chip 6 in both the x-direction and the y-direction is improved.

In this modification, all of the plurality of pad portions 38 are concave pad portions 381. According to such a configuration, the effect of improving the positional deviation when the IC chip 6 is mounted on the flip chip can be more reliably obtained.

In the second embodiment, a glaze layer 2 including a heater glaze portion 22 and a glass layer 23 is arranged on the substrate 1, and various layers are formed on the glaze layer 2 by a thin film forming technique. There is. Instead of this configuration, various layers may be formed on the glaze layer 2 by a thick film forming technique.

In the second embodiment, the substrate 1 is made of ceramic such as Al ₂ O ₃ , but instead, the substrate 1 may be made of a semiconductor substrate such as a silicon substrate. In the case of the substrate 1 made of a semiconductor substrate, a plurality of thermal printheads are manufactured from the semiconductor substrate by dividing the semiconductor substrate into a plurality of pieces.

The thermal printhead according to the present disclosure is not limited to the above-described embodiment. The specific configuration of each part of the thermal print head according to the present disclosure can be freely redesigned.

In the above embodiment, the case where the IC chip mounting structure according to the present disclosure is applied to the thermal printhead has been described, but the IC chip mounting structure of the present disclosure may be applied to other electronic devices and the like. In the IC chip mounting structure according to the present disclosure, it is preferable that the main surface of the base material on which the IC chip is flip-chip mounted is not provided with an insulating film. Examples of the insulating film include a resist film such as a solder resist in a printed circuit board and a resin film such as a polyimide film in a flexible substrate.

The present disclosure includes the following appendices.

[Appendix 1]
A base material having a main surface facing one side in the thickness direction, and a support member having a wiring layer arranged on the main surface,
An IC chip with a mounting surface and
It is a mounting structure comprising a plurality of conductive bonding materials arranged on the mounting surface, and the IC chip is flip-chip mounted on the support member.
The support member is arranged corresponding to the plurality of conductive bonding materials and has a plurality of pad portions including at least two concave pad portions.
The concave pad portion has a bottom surface and an inner wall surface facing the bottom surface when viewed in the thickness direction of the base material.
The inner wall surface is an IC chip mounting structure composed of the wiring layer.
[Appendix 2]
The IC chip mounting structure according to Appendix 1, wherein an insulating film is not provided on the main surface of the base material.
[Appendix 3]
A resistor layer arranged on the main surface and containing a plurality of heat generating portions arranged in the main scanning direction is provided.
The wiring layer is conductive to the resistor layer.
The IC chip is a thermal print head having the mounting structure according to Appendix 2, which controls the current flowing through each of the heat generating portions.
[Appendix 4]
The wiring layer includes a first layer arranged on the main surface and a second layer arranged on a part of the first layer.
The inner wall surface is composed of the second layer.
The thermal print head according to Appendix 3, wherein the bottom surface is composed of the first layer.
[Appendix 5]
The thermal print head according to Appendix 4, wherein the concave pad portion faces one side in the main scanning direction and the other side in the main scanning direction, and has a pair of inner wall surfaces facing each other.
[Appendix 6]
The thermal print head according to Appendix 4, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material.
[Appendix 7]
The bottom surface is composed of a portion of the wiring layer having a relatively small thickness.
The thermal print head according to Appendix 3, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material.
[Appendix 8]
The bottom surface is composed of a portion of the main surface exposed from the wiring layer.
The thermal print head according to Appendix 3, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material.
[Appendix 9]
A plurality of the plurality of pad portions are arranged in each of the main scanning direction and the sub-scanning direction.
The thermal print head according to any one of Supplementary note 3 to 8, wherein the plurality of pad portions located at the four corners in the main scanning direction and the sub-scanning direction are the concave pad portions.
[Appendix 10]
The thermal print head according to any one of Supplementary note 3 to 8, wherein the plurality of pad portions are all concave pad portions.
[Appendix 11]
The thermal print head according to any one of Supplementary note 3 to 10, wherein the conductive bonding material is a solder bump.
[Appendix 12]
The thermal printhead according to any one of Supplementary note 3 to 11, wherein at least a part of the wiring layer is made of a material containing Ag.
[Appendix 13]
The IC chip is arranged on the upstream side in the sub-scanning direction with respect to the plurality of heat generating portions.
The wiring layer is arranged in a region on the upstream side in the sub-scanning direction with respect to the first metal portion connected to the plurality of heat generating portions and the second metal portion connected to the plurality of conductive bonding materials. The thermal print head according to any one of Supplementary note 3 to 11, including the section.
[Appendix 14]
The thermal printhead according to Appendix 13, wherein the first metal part is made of a material containing Au, and the second metal part is made of a material containing Ag.
[Appendix 15]
The thermal printhead according to any one of Appendix 3 to 14, wherein the substrate comprises a substrate and a glaze layer arranged on the substrate and having the main surface.
[Appendix 16]
The thermal print head according to Appendix 15, wherein the substrate is made of ceramic.
[Appendix 17]
The process of preparing the base material and
A step of forming a support member composed of the base material and the wiring layer by forming a wiring layer on the base material, and a step of forming the support member.
A step of forming a resistance layer that overlaps a part of the wiring layer on the support member when viewed in the thickness direction of the base material.
A step of flip-chip mounting an IC chip in which a plurality of conductive bonding materials are arranged on a mounting surface is provided on the substrate.
In the step of forming the support member, a plurality of pad portions corresponding to the plurality of conductive bonding materials including at least two concave pad portions are formed.
A method for manufacturing a thermal print head, wherein the concave pad portion has a bottom surface and an inner wall surface facing the bottom surface when viewed in the thickness direction of the base material.
[Appendix 18]
The steps for forming the support member include a first layer forming step of forming the first layer on the base material and a second layer forming the inner wall surface on the first layer. The method for manufacturing a thermal printhead according to Appendix 17, which comprises a layer forming step.
[Appendix 19]
The first layer forming step includes a step of printing a negative type first photosensitive metal paste on the base material, a step of partially exposing the first photosensitive metal paste, and the first photosensitive metal paste. It includes a step of removing a portion of the metal paste other than the exposed portion and a step of firing the first photosensitive metal paste.
The second layer forming step includes a step of printing a negative type second photosensitive metal paste on the base material, a step of partially exposing the second photosensitive metal paste, and the second photosensitive metal paste. The method for manufacturing a thermal printhead according to Appendix 18, further comprising a step of removing a portion of the metal paste other than the exposed portion and a step of firing the second photosensitive metal paste.
[Appendix 20]
The method for manufacturing a thermal printhead according to Appendix 19, wherein at least the second photosensitive metal paste among the first photosensitive metal paste and the second photosensitive metal paste contains Ag.

A1, A11, A12, A13, A14, A15, A2, A21: Thermal printhead 1: Substrate 2: Glaze layer 21: Main surface 211: Bottom surface 212: Bottom surface 22: Heater glaze portion 23: Glass layer 231: Main surface 232 : Bottom surface 3: Wiring layer 3a: First metal part 3b: Second metal part 3c: Base layer 3d: Plating layer 301: Surface 302: Hole 303: Inner wall surface 304: Concave surface 305: Top surface 306: Bottom surface 307: Inner wall surface 31: First layer 311: Surface 312: Bottom surface 313: Bottom surface 314: Inner wall surface 315: Inner wall surface 316: Intermediate surface 317: Inner wall surface 318: Inner wall surface 32: Second layer 321: Top surface 322: Inner wall surface 33: Common electrode 331 : Common part 332: Common electrode band-shaped part 34: Individual electrode 35: Individual electrode band-shaped part 36: Connecting part 37: Signal wiring part 38: Pad part 4: Resistor layer 41: Heat-generating part 5: Protective layer 6: IC chip 61 : Mounting surface 62: Conductive bonding material 71: Protective resin 72: Connector 81: Platen roller 82: Printing medium

Claims (20)

A base material having a main surface facing one side in the thickness direction, and a support member having a wiring layer arranged on the main surface,
An IC chip with a mounting surface and
It is a mounting structure comprising a plurality of conductive bonding materials arranged on the mounting surface, and the IC chip is flip-chip mounted on the support member.
The support member is arranged corresponding to the plurality of conductive bonding materials and has a plurality of pad portions including at least two concave pad portions.
The concave pad portion has a bottom surface and an inner wall surface facing the bottom surface when viewed in the thickness direction of the base material.
The inner wall surface is an IC chip mounting structure composed of the wiring layer. The IC chip mounting structure according to claim 1, wherein an insulating film is not provided on the main surface of the base material. A resistor layer arranged on the main surface and containing a plurality of heat generating portions arranged in the main scanning direction is provided.
The wiring layer is conductive to the resistor layer.
The IC chip is a thermal print head having the mounting structure according to claim 2, which controls the current flowing through each of the heat generating portions. The wiring layer includes a first layer arranged on the main surface and a second layer arranged on a part of the first layer.
The inner wall surface is composed of the second layer.
The thermal print head according to claim 3, wherein the bottom surface is composed of the first layer. The thermal print head according to claim 4, wherein the concave pad portion faces one side in the main scanning direction and the other side in the main scanning direction, and has a pair of inner wall surfaces facing each other. The thermal print head according to claim 4, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material. The bottom surface is composed of a portion of the wiring layer having a relatively small thickness.
The thermal print head according to claim 3, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material. The bottom surface is composed of a portion of the main surface exposed from the wiring layer.
The thermal print head according to claim 3, wherein the inner wall surface forms an annular shape surrounding the bottom surface when viewed in the thickness direction of the base material. A plurality of the plurality of pad portions are arranged in each of the main scanning direction and the sub-scanning direction.
The thermal print head according to any one of claims 3 to 8, wherein among the plurality of pad portions, those at the four corners in the main scanning direction and the sub-scanning direction are the concave pad portions. The thermal print head according to any one of claims 3 to 8, wherein the plurality of pad portions are all concave pad portions. The thermal print head according to any one of claims 3 to 10, wherein the conductive bonding material is a solder bump. The thermal printhead according to any one of claims 3 to 11, wherein at least a part of the wiring layer is made of a material containing Ag. The IC chip is arranged on the upstream side in the sub-scanning direction with respect to the plurality of heat generating portions.
The wiring layer is arranged in a region on the upstream side in the sub-scanning direction with respect to the first metal portion connected to the plurality of heat generating portions and the second metal portion connected to the plurality of conductive bonding materials. The thermal print head according to any one of claims 3 to 11, further comprising a part. The thermal print head according to claim 13, wherein the first metal part is made of a material containing Au, and the second metal part is made of a material containing Ag. The thermal printhead according to any one of claims 3 to 14, wherein the substrate comprises a substrate and a glaze layer arranged on the substrate and having the main surface. The thermal printhead according to claim 15, wherein the substrate is made of ceramic. The process of preparing the base material and
A step of forming a support member composed of the base material and the wiring layer by forming a wiring layer on the base material, and a step of forming the support member.
A step of forming a resistance layer that overlaps a part of the wiring layer on the support member when viewed in the thickness direction of the base material.
A step of flip-chip mounting an IC chip in which a plurality of conductive bonding materials are arranged on a mounting surface is provided on the substrate.
In the step of forming the support member, a plurality of pad portions corresponding to the plurality of conductive bonding materials including at least two concave pad portions are formed.
A method for manufacturing a thermal print head, wherein the concave pad portion has a bottom surface and an inner wall surface facing the bottom surface when viewed in the thickness direction of the base material. The steps for forming the support member include a first layer forming step of forming the first layer on the base material and a second layer forming the inner wall surface on the first layer. The method for manufacturing a thermal printhead according to claim 17, which comprises a layer forming step. The first layer forming step includes a step of printing a negative type first photosensitive metal paste on the base material, a step of partially exposing the first photosensitive metal paste, and the first photosensitive metal paste. It includes a step of removing a portion of the metal paste other than the exposed portion and a step of firing the first photosensitive metal paste.
The second layer forming step includes a step of printing a negative type second photosensitive metal paste on the base material, a step of partially exposing the second photosensitive metal paste, and the second photosensitive metal paste. The method for manufacturing a thermal printhead according to claim 18, further comprising a step of removing a portion of the metal paste other than the exposed portion and a step of firing the second photosensitive metal paste. The method for manufacturing a thermal printhead according to claim 19, wherein at least the second photosensitive metal paste among the first photosensitive metal paste and the second photosensitive metal paste contains Ag.

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