JP6719232B2 - Plated film forming method and liquid jet head manufacturing method - Google Patents

Description

The present invention relates to a plating film forming method for forming a plating film on a surface of a substrate and a method for manufacturing a liquid jet head for forming a plating film on an exposed surface of a piezoelectric substrate.

The method of forming a metal film on the surface of an insulating substrate by electroless plating has been put to practical use in many fields. For example, Patent Document 1 describes a method of forming a copper foil on the surface of a printed board by an electroless plating method. The printed board on which the through holes are formed is sequentially dipped in a degreasing tank, a dehydration tank, a catalyst addition tank, an activation tank, an electroless plating tank, and a neutralization tank to form a copper foil on the surface of the printed board. Then, in the degreasing tank to the activation tank, the printed circuit board is oscillated once every cycle/2 seconds. Specifically, the printed circuit board fixed to the vertical bar is immersed in the treatment liquid, and the vertical bar is pushed and pulled by a rocking device to rock the printed circuit board in a direction perpendicular to the substrate surface. Swing the printed circuit board to shorten the processing time of each tank. In the electroless plating bath, the printed circuit board is vibrated at a cycle of several 100 Hz (preferably 500 Hz). Specifically, the printed circuit board is fixed to a vertical bar, immersed in a plating solution, and the vertical bar is vibrated in a direction perpendicular to the plate surface of the printed circuit board by a vibration generator. It is described that the bubbles remaining in the through holes can be removed by vibrating the substrate.

In addition, Patent Document 2 describes a liquid ejecting head that uses a piezoelectric member. A large number of grooves are formed on a piezoelectric substrate, and electrodes are formed on the side and bottom surfaces of the grooves by electroless plating to form channels. PZT (lead zirconate titanate) ceramics is used as the piezoelectric substrate, and a nickel film is deposited to a thickness of 1 μm to 5 μm by electroless plating to form an electrode in the groove.

Further, Patent Document 3 describes a method of manufacturing a liquid jet head using a piezoelectric member. A large number of grooves are formed in the piezoelectric member bonded to the surface of the substrate. Specifically, the piezoelectric member is cut by a diamond wheel or the like in the thickness direction to a depth reaching the substrate. The groove width is 80 μm and the groove depth is 300 μm. Next, a nickel thin film is formed on all exposed surfaces of the piezoelectric member and the substrate by electroless plating. Next, the nickel thin film is patterned using laser light to form electrodes on the side and bottom surfaces of each groove.

Further, Patent Document 4 describes a method of manufacturing a liquid jet head. A large number of grooves are formed on the surface of the piezoelectric substrate, and electrodes made of a nickel thin film are formed on the side and bottom surfaces of the grooves by electroless plating. Specifically, the piezoelectric substrate on which the groove is formed is subjected to ultrasonic cleaning, degreasing cleaning, patterning of the resist film, and surface roughening treatment in sequence. Then, the sensitizing and activating process is repeated to deposit the plating catalyst on the side and bottom surfaces of the groove, and then the electrodes are formed on the side and bottom surfaces of the groove by electroless plating. At the time of the sensitizing and activating process, ultrasonic waves having a frequency of 20 kHz to 100 kHz are added to the aqueous solution. This describes that stannous chloride and palladium chloride can be diffused to deposit metallic palladium on the substrate surface.

Japanese Patent No. 2865637 JP, 2002-103630, A JP, 2009-202475, A JP, 2014-177075, A

When a plating film is formed on the surface of the substrate by electroless plating, if foreign matter or bubbles adhere to the surface of the substrate or if the surface of the substrate is prone to chipping, chipping or pinholes will occur in the plating film Cause deterioration of the film quality. In addition, there are cases where unevenness or holes are present on the surface of the substrate, and a plating film is formed on the side surface or the bottom surface of the unevenness or holes by electroless plating. For example, in Patent Document 1, a through hole is formed in a substrate, and a plating film is formed on the inner side surface of this through hole. If unevenness or through holes exist on the surface of the substrate, bubbles are likely to adhere to the recesses or through holes. If the plating process is performed in a state where air bubbles are attached, the air bubble locations cause a chipping of the plating film, which causes deterioration of the quality of the plating film. In Patent Document 1, the substrate is swung in the cleaning tank in the direction perpendicular to the substrate surface at a cycle of 0.5 Hz, and in the plating tank, the substrate is swung in the direction perpendicular to the substrate surface at several 100 Hz, and remains in the through hole. Remove bubbles. However, when a recess that does not penetrate the substrate surface is formed, the swinging method of Patent Document 1 does not sufficiently transfer convection and vibration to the solution in the recess, and it is not possible to remove bubbles and foreign matter in the recess. Alternatively, the film thickness of the plating film becomes uneven.

Further, in Patent Documents 2 to 4, a plating film is formed by electroless plating on the surface of the piezoelectric substrate in which a groove having a depth deeper than the opening width of the opening is formed. Also in this case, as in Patent Document 1, it is necessary to remove bubbles and foreign matter adhering to the groove before forming the plating film. For example, in Patent Document 4, the piezoelectric substrate is cleaned or ultrasonic waves having a frequency of 20 kHz to 100 kHz are applied to the cleaning liquid to remove foreign matter or bubbles adhering to the surface, or a plating catalyst is applied. However, the piezoelectric material used is PZT ceramics and is composed of crystal grains. When the groove is formed by the cutting method, fine foreign matter is likely to remain on the surface of the groove, and it is difficult to completely remove the adhered foreign matter by ultrasonic cleaning. Further, when the surface of the groove is subjected to etching treatment, the crystal grain boundaries appearing on the surface are eroded and the bonding force between the crystal grains is reduced. When ultrasonic waves are applied to such a surface, the ultrasonic waves may act strongly on the piezoelectric substrate and crystal grains may drop off from the surface. Further, when ultrasonic waves are applied to the plating catalyst attached to the surface of the substrate, the plating catalyst is partly peeled off and the thickness of the plating film becomes uneven.

The plating film forming method of the present invention includes a cleaning step of immersing a substrate in a cleaning solution and cleaning, and a frequency of 10 Hz to 200 Hz (however, 10 to 60 Hz and 100 to 200 Hz) in which the substrate is immersed in an electroless plating solution. (Excluding the above), the electroless plating step of vibrating in a direction parallel to the exposed surface of the substrate at a low frequency to form a plating film on the exposed surface of the substrate.

The cleaning step is a step of cleaning the substrate by immersing the substrate in the cleaning liquid and vibrating the substrate at a low frequency of 20 Hz to 400 Hz.

A liquid jet head manufacturing method according to the present invention includes a groove forming step of forming a plurality of grooves in parallel on a piezoelectric substrate, a cleaning step of immersing the piezoelectric substrate in a cleaning liquid to clean the piezoelectric substrate, and the piezoelectric element. The body substrate is immersed in an electroless plating solution and the piezoelectric substrate is vibrated in a direction parallel to the exposed surface of the substrate at a low frequency of 10 Hz to 200 Hz (excluding 10 to 60 Hz and 100 to 200 Hz). And an electroless plating step of forming a plating film on the exposed surface of the piezoelectric substrate.

The cleaning step is a step of immersing the piezoelectric substrate in the cleaning liquid and vibrating the piezoelectric substrate at a low frequency of 20 Hz to 400 Hz for cleaning.

In addition, the electroless plating step includes a step of vibrating the piezoelectric substrate in the longitudinal direction of the groove to form the plating film.

The cleaning step is a step of cleaning the piezoelectric substrate by vibrating it in the longitudinal direction of the groove.

Also, a first cleaning step of cleaning the exposed surface of the piezoelectric substrate by the cleaning step, an etching step of etching the exposed surface of the piezoelectric substrate, and an exposed surface of the piezoelectric substrate by the cleaning step. A second cleaning step and a catalyst adhering step of adhering a plating catalyst to the exposed surface of the piezoelectric substrate before the electroless plating step are provided.

Further, a photosensitive resin layer forming step of setting a photosensitive resin layer on the surface of the piezoelectric substrate before the groove forming step, and a photosensitive resin layer of removing the photosensitive resin layer after the electroless plating step. And a removal step.

The plating film forming method according to the present invention includes a cleaning step of immersing a substrate in a cleaning liquid and cleaning the substrate, and immersing the substrate in an electroless plating liquid to make the substrate have a frequency of 10 Hz to 200 Hz (provided that 10 to 60 Hz and 100 to 200 Hz are used. (Excluding), the electroless plating step of vibrating in a direction parallel to the exposed surface of the substrate at a low frequency to form a plating film on the exposed surface of the substrate. As a result, metal ions are newly supplied to the surface of the substrate and the plated film can be formed evenly.

It is a flowchart of a plating film forming method concerning a first embodiment of the present invention. It is a figure for demonstrating the electroless-plating process of the plating film forming method which concerns on 1st embodiment of this invention. FIG. 6 is a process drawing of the method of manufacturing the liquid jet head according to the second embodiment of the present invention. FIG. 8 is a diagram for explaining a manufacturing method for the liquid jet head according to the second embodiment of the present invention. FIG. 9 is a process diagram of a method for manufacturing a liquid jet head according to a third embodiment of the present invention. FIG. 6 is a diagram for explaining each step in the method of manufacturing the liquid jet head according to the third embodiment of the present invention. FIG. 6 is a diagram for explaining each step in the method of manufacturing the liquid jet head according to the third embodiment of the present invention. FIG. 6 is a diagram for explaining each step in the method of manufacturing the liquid jet head according to the third embodiment of the present invention.

(First embodiment)
FIG. 1 is a process diagram of a plating film forming method according to the first embodiment of the present invention. FIG. 2 is a diagram for explaining the electroless plating process according to the first embodiment of the present invention. As shown in FIG. 1, the plating film forming method of the present invention includes a cleaning step Sx for cleaning the substrate 1 and an electroless plating step Sy for forming a plating film on the substrate surface S (exposed surface, the same hereinafter) of the substrate 1. With. In the cleaning step Sx, the substrate 1 is immersed in the cleaning liquid 2 for cleaning. In the electroless plating step Sy, the substrate 1 is immersed in the electroless plating solution 3 and the substrate 1 is vibrated at a first low frequency f1 having a frequency of 10 Hz to 200 Hz to form a plating film on the substrate surface S of the substrate 1. Thereby, the metal ions are newly supplied to the substrate surface S where the metal ions of the electroless plating solution 3 are consumed, and the plating film can be formed evenly on the substrate surface S.

This will be specifically described. FIG. 2 is a schematic diagram showing a state of forming a plating film on the substrate surface S of the substrate 1, and FIG. 2A is a schematic front view of the substrate 1 viewed from the front (viewed from the normal direction of the substrate surface S). 2B is a schematic side view of the substrate 1 viewed from the side (the substrate 1 viewed from the substrate surface direction). First, in the cleaning step Sx, the substrate surface S is immersed in a cleaning liquid for cleaning. Next, in the electroless plating step Sy, a plurality of substrates 1 are fixed to a substrate holder H having a basket shape and six sides open, and an end of a support arm N connected to the substrate holder H is connected to a vibration generator M. To do. The plating bath Bb is filled with the electroless plating solution 3, and the substrate 1 is immersed in the electroless plating solution 3 with the substrate surface S oriented in the vertical direction indicated by the arrow. Then, the vibration generator M is driven to vibrate the support arm N in the vertical direction at a stroke of 0.1 mm to 5 mm at a first low frequency f1 having a frequency F of 10 Hz to 200 Hz. Therefore, the substrate 1 vibrates in the electroless plating solution 3 in the vertical direction at the first low frequency f1 of 10 Hz to 200 Hz and in the direction parallel to the substrate surface S of the substrate 1. As a result, the metal ions are newly supplied to the substrate surface S where the metal ions of the electroless plating solution 3 are consumed, and the plating film can be formed evenly on the substrate surface S. When applying the first low-frequency f1 vibration to the substrate 1, the vibration generator M is driven to drive the vibration generator M after a lapse of a predetermined time from the start of the electroless plating, for example, 1 to 5 minutes. Is preferably vibrated. If vibration is applied immediately after the start of electroless plating, the plating catalyst adhering to the substrate surface S may drop off from the substrate surface S, causing unevenness in the thickness of the plated film.

Here, for the substrate 1, a conductor, a piezoelectric body, an insulator, a synthetic resin, or the like can be used. As the cleaning liquid 2, pure water, an organic solvent, a degreasing cleaning liquid containing a surfactant, or the like can be used. As the electroless plating solution 3, a plating solution that deposits Ni, Au, Ag, or the like can be used.

In the plating film forming method of the present invention, it is not essential to immerse the substrate 1 in the cleaning liquid 2 and apply vibration to the substrate 1, but the apparatus shown in FIG. 2 can be used also in the cleaning step Sx. That is, the plurality of substrates 1 are fixed to the substrate holder H, and the ends of the support arms N connected to the substrate holder H are connected to the vibration generator M. The cleaning bath Ba is filled with the cleaning liquid 2, and the substrate 1 is immersed in the cleaning liquid 2 with the substrate surface S oriented in the vertical direction indicated by the arrow. Then, the vibration generator M is driven to vibrate the support arm N in the vertical direction at a second low frequency f2 having a frequency F of 20 Hz to 400 Hz with a stroke of 0.1 mm to 5 mm. Therefore, the substrate 1 vibrates in the cleaning liquid 2 at the second low frequency f2 of 20 Hz to 400 Hz in the vertical direction and in the direction parallel to the substrate surface S of the substrate 1. As a result, fine foreign matter and bubbles can be removed from the substrate surface S of the substrate 1 by the cleaning step Sx, and the quality of the plated film 4 formed by the electroless plating step Sy is improved. That is, a plated film having no pinhole can be formed easily and evenly.

The second low frequency f2 is changed according to the size of foreign matter or bubbles adhering to the surface of the substrate 1. The present inventor has conducted an experiment to find that the diameter of an object to be cleaned and the frequency of vibration applied to the substrate 1 are inversely proportional to each other, and the frequency is F (Hz) and the diameter of the cleaning object is R (m). It has been found that there is a relationship of the following formula (1). Here, k is a constant.
F=k×10 ⁻⁴ /R (1)
That is, as the diameter R of the object to be cleaned is increased, the frequency F of the second low frequency f2 is decreased, and as the diameter R of the object to be cleaned is increased, the frequency F of the second low frequency f2 is increased. good. When the diameters of the objects to be cleaned are dispersed, the frequency F of vibration applied to the substrate 1 should also be changed within the range of 20 Hz to 400 Hz. In other words, by vibrating at the specific frequency F which is the second low frequency f2, the object having the specific diameter R is selectively removed from the substrate surface S, and the object having the other diameter R′ is removed. Can be left on.

According to the method for forming a plating film of the present invention, even when a concave portion, for example, a large number of concaves and convexes or grooves are present on the substrate surface S of the substrate 1, metal ions are easily entangled in the concaves and convexes. A plated film can be deposited. In the first embodiment, the vibration direction of the substrate 1 is vibrated in the direction parallel to the substrate surface S, but the present invention is not limited to this, and the vibration direction of the substrate 1 is vibrated in the direction perpendicular to the substrate surface S. May be. For example, when a through-hole is formed in the substrate 1 and a plating film is to be formed on the side surface of the through-hole by electroless plating, the vibration direction of the substrate 1 is changed in the cleaning step Sx and the electroless plating step Sy. The direction is perpendicular to the surface S. Thus, in the cleaning step Sx, foreign matters and bubbles adhering to the side surface of the through hole can be removed, and in the electroless plating step Sy, a new electroless plating solution 3 can be supplied to the through hole. .. Further, when the elongated groove is formed on the substrate 1, the vibrating direction of the substrate 1 is vibrated in a direction parallel to the longitudinal direction of the groove on the substrate surface S. Thereby, in the cleaning step Sx, foreign matters and bubbles adhering to the inner side surface and the bottom surface of the groove can be removed, and new electroless plating solution 3 can be supplied to the bottom portion of the groove in the electroless plating step Sy. ..

(Second embodiment)
FIG. 3 is a process drawing of the method for manufacturing a liquid jet head according to the second embodiment of the present invention. FIG. 4 is a diagram for explaining a method of manufacturing the liquid jet head according to the second embodiment of the present invention. FIG. 4A is a schematic sectional view of the piezoelectric substrate 1a after the groove forming step Sm. FIG. 4B is a diagram for explaining the cleaning step Sx and the electroless plating step Sy. FIG. 4C is a schematic sectional view of the piezoelectric substrate 1a after the electroless plating step Sy. FIG. 4D is a schematic sectional view of the liquid jet head 10 after the head assembly step Sz. The same portions or portions having the same function are designated by the same reference numerals.

As shown in FIG. 3, in the liquid jet head manufacturing method of the present invention, a groove forming step Sm of forming a plurality of grooves 5 in parallel on the piezoelectric substrate 1a, a cleaning step Sx of cleaning the piezoelectric substrate 1a, An electroless plating step Sy of forming a plating film 4 on the exposed surface Ep of the piezoelectric substrate 1a (the substrate surface S and the inner surface of the groove 5), and a head assembly step of assembling the liquid jet head 10 using this piezoelectric substrate 1a. Sz and. Hereinafter, a specific description will be given with reference to FIG.

FIG. 4A is a schematic sectional view in a direction orthogonal to the longitudinal direction of the groove 5 of the piezoelectric substrate 1a. In the groove forming step Sm, a plurality of grooves 5 are formed in parallel on the piezoelectric substrate 1a. The piezoelectric substrate 1a is polarized in the direction normal to the substrate surface S. The piezoelectric substrate 1a is ground from one substrate surface S side using a dicing blade or a diamond wheel to form a plurality of grooves 5 having a predetermined depth. PZT ceramics can be used as the piezoelectric substrate 1a. The depth of the groove 5 is 300 μm to 400 μm, the length of the groove 5 is 1 mm to several mm, the width of the groove 5 is several 10 μm to 100 μm, and the width of the side wall 9 between the grooves 5 ( The thickness) is several 10 μm to 100 μm. Several hundred or more grooves 5 are formed in parallel. In the piezoelectric substrate 1a, the piezoelectric substrate may be used only for the side walls 9 between the grooves 5 and the insulating substrate may be used as a lower material for holding the side walls 9.

FIG. 4B shows how the piezoelectric substrate 1a is cleaned in the cleaning step Sx, and the left view is a schematic view of the substrate surface S of the piezoelectric substrate 1a viewed from the front (viewed from the direction perpendicular to the substrate surface S). The right diagram is a schematic view of the piezoelectric substrate 1a viewed from the side (viewed from the direction parallel to the substrate surface S). In the cleaning step Sx, the piezoelectric substrate 1a is immersed in the cleaning liquid 2 to vibrate the piezoelectric substrate 1a at a second low frequency f2 having a frequency of 20 Hz to 400 Hz for cleaning. Specifically, as shown in FIG. 4B, the plurality of piezoelectric substrates 1a are fixed to the substrate holder H. The substrate holder H includes an upper holding portion Ha and a lower holding portion Hb having saw-tooth-shaped irregularities. A plurality of piezoelectric substrates 1a are sandwiched in parallel and fixed between the concave portions of the upper and lower holding portions Ha and Hb facing each other. The support arm N is connected to the substrate holder H, and the opposite end of the support arm N is connected to the vibration generator M. The cleaning bath Ba is filled with the cleaning liquid 2, and the piezoelectric substrate 1a is dipped in the cleaning liquid 2 with the substrate surface S oriented in the vertical direction indicated by the arrow.

In the present embodiment, the longitudinal direction of the groove 5 of the piezoelectric substrate 1a is directed in the vertical direction which is the vibration direction, but the present invention is not limited to this arrangement. However, by making the longitudinal direction of the groove 5 coincide with the vibration direction, the vibration of the cleaning liquid 2 is transmitted to the inside of the groove 5, and the foreign matter attached to the inner surface (exposed surface) can be effectively removed. Therefore, it is preferable that the substrate holder H mounts and fixes a plurality of piezoelectric substrates 1a with the longitudinal direction of the groove 5 oriented in the vibration direction.

Then, the vibration generator M vibrates the support arm N in the vertical direction. The support arm N vibrates at a stroke of 0.1 mm to 5 mm at a second low frequency f2 having a frequency F of 20 Hz to 400 Hz. Therefore, the piezoelectric substrate 1a vibrates vertically in the cleaning liquid 2 with a stroke of 0.1 mm to 5 mm at the second low frequency f2 having a frequency F of 20 Hz to 400 Hz. As the cleaning liquid 2, pure water, an organic solvent, a degreasing cleaning liquid containing a surfactant, or the like can be used. As a result, it is possible to remove foreign matter adhering to the side surface and the bottom surface of the groove 5, for example, grinding powder and bubbles generated in the groove forming step Sm. The second low frequency f2 is preferably changed according to the size of foreign matter or bubbles adhering to the substrate surface S of the piezoelectric substrate 1a. As described above, the frequency F and the diameter R of the object to be cleaned have a relationship of approximately the formula (1). Therefore, the larger the diameter R of the object to be cleaned, the frequency F of the second low frequency f2. And the frequency F of the second low frequency f2 should be increased as the diameter R of the object to be cleaned decreases. Further, since the piezoelectric substrate 1a is vibrated by the second low frequency f2 which is the specific frequency F, particles of other sizes, for example, crystal grains of PZT ceramics are dropped or cracks are generated on the side wall 9. There is no.

The device configuration shown in FIG. 4B is an example of the present invention. For example, the substrate holder H may hold the piezoelectric substrate 1a so that the substrate surface S is horizontal, and the vibration generator M may vibrate the substrate holder H horizontally via the support arm N. .. In this case, the substrate holder H is vibrated so that the longitudinal direction of the groove 5 is the vibrating direction of the piezoelectric substrate 1a.

Next, in the electroless plating step Sy, the piezoelectric substrate 1a is immersed in the electroless plating solution 3 to form the plating film 4 on the exposed surface Ep of the piezoelectric substrate 1a. The apparatus shown in FIG. 4B can be used in the electroless plating step Sy. The substrate holder H fixes a plurality of piezoelectric substrates 1a. Specifically, the substrate holder H is fixed by sandwiching a plurality of piezoelectric substrates 1a in parallel in the vertical direction between the concave portions of the upper holding portion Ha and the lower holding portion Hb facing each other. The support arm N is connected to the substrate holder H, and the opposite end of the support arm N is connected to the vibration generator M. The plating bath Bb is filled with the electroless plating solution 3, and the piezoelectric substrate 1 a is dipped in the electroless plating solution 3 with the longitudinal direction of the groove 5 oriented in the vertical direction indicated by the arrow. In the present invention, it is not essential to orient the longitudinal direction of the groove 5 in the vibration direction of the piezoelectric substrate 1a, but by orienting the longitudinal direction of the groove 5 in the vibration direction of the piezoelectric substrate 1a, the electroless plating solution The vibration of 3 can be easily transmitted to the inside of the groove 5.

Then, the vibration generator M is driven to vibrate the support arm N in the vertical direction to vibrate the plurality of piezoelectric substrate 1a in the longitudinal direction of the groove 5. If the vibration generator M vibrates the support arm N at the first low frequency f1 having the frequency F of 10 Hz to 200 Hz, the plurality of piezoelectric substrate 1a also vibrates at the first low frequency f1 having the frequency F of 10 Hz to 200 Hz. To do. Also in this case, the piezoelectric substrate 1a vibrates in the vertical direction with a stroke of 0.1 mm to 5 mm. As a result, the new electroless plating solution 3 is supplied to the inside of the groove 5, and unevenness in the thickness of the plating film 4 is suppressed. Further, although gas is generated with the deposition of the plating film 4, it is possible to prevent the gas from forming bubbles and closing the opening of the groove 5.

FIG. 4C is a schematic cross-sectional view in a direction orthogonal to the longitudinal direction of the groove 5 of the piezoelectric substrate 1a having the plated film 4 formed by the electroless plating step Sy. The plating film 4 is formed on the exposed surface Ep of the piezoelectric substrate 1a.

Next, in the head assembly step Sz, the liquid jet head 10 is assembled using the piezoelectric substrate 1a. FIG. 4D is a schematic sectional view of the liquid jet head 10 in the longitudinal direction of the groove 5 after assembly. The cover plate 12 is bonded to the substrate surface S of the piezoelectric substrate 1a on which the plating film 4 is formed, and the nozzle plate 13 is bonded to the cover plate 12 and the front end face Fp of the piezoelectric substrate 1a. A liquid supply chamber 12a is formed in the cover plate 12, and a nozzle 13a is formed in the nozzle plate 13, both of which communicate with the groove 5. The plating film 4 on the side surface of the groove 5 serves as a drive electrode for driving the side wall 9, and the plating film 4 behind the piezoelectric substrate 1a serves as an electrode terminal. The method of manufacturing a liquid jet head according to the present invention is not limited to the edge shoot type liquid jet head 10 shown in FIG. 4D, but can be applied to a side shoot type or liquid circulation type liquid jet head. ..

(Third embodiment)
FIG. 5 is a process diagram of a method for manufacturing a liquid jet head according to the third embodiment of the present invention. 6 to 8 are views for explaining each step in the method of manufacturing the liquid jet head according to the third embodiment of the present invention. 6A to 6D are schematic sectional views of the piezoelectric substrate 1a, and FIG. 6E is an explanatory diagram of the cleaning method or the electroless plating method. 7A to 7D are schematic sectional views of the piezoelectric substrate 1a. FIG. 8 is a schematic exploded perspective view of the liquid jet head 10. The same portions or portions having the same function are designated by the same reference numerals.

A method for manufacturing a liquid jet head according to a third embodiment of the present invention includes a preparatory step S1 of preparing a piezoelectric substrate 1a and a photosensitive resin layer for forming a photosensitive resin layer 6 on a substrate surface S of the piezoelectric substrate 1a. Forming step S2, pattern forming step S3 for patterning the photosensitive resin layer 6, groove forming step Sm for forming a plurality of grooves 5 on the substrate surface S of the piezoelectric substrate 1a, and exposed surface Ep of the piezoelectric substrate 1a. Cleaning step Sx1 for cleaning the exposed surface Ep of the piezoelectric substrate 1a, an etching step S5 for etching the exposed surface Ep of the piezoelectric substrate 1a, and an exposed surface Ep of the piezoelectric substrate 1a. A second cleaning step Sx2 for cleaning the substrate, an acid treatment step S6 for treating the exposed surface Ep of the piezoelectric substrate 1a with an acid, a catalyst attachment step S7 for attaching a plating catalyst to the exposed surface Ep of the piezoelectric substrate 1a, and a plating catalyst. , The electroless plating step Sy for depositing the plating film 4 on the exposed surface Ep, the photosensitive resin layer removing step S8 for removing the photosensitive resin layer 6, and the liquid jet head 10 using the piezoelectric substrate 1a. And a head assembling step Sz.

This will be specifically described. In the preparation step S1, as shown in FIG. 6A, the piezoelectric substrate 1a is prepared. As the piezoelectric substrate 1a, it is possible to use a PZT ceramics plate that is polarized in the direction normal to the substrate surface S. For example, a chevron-type piezoelectric substrate 1a is used in which a piezoelectric substrate having a polarization P in the normal direction and a piezoelectric substrate having a polarization (−P) in the opposite direction are laminated and bonded at the position of the polarization boundary Z. be able to. The present invention is not limited to the chevron type piezoelectric substrate 1a.

Next, in the photosensitive resin layer forming step S2, as shown in FIG. 6B, the photosensitive resin layer 6 is provided on the surface (substrate surface S) of the piezoelectric substrate 1a. A resist film can be used as the photosensitive resin layer 6. A resist film may be provided by laminating a film resist on the substrate surface S of the piezoelectric substrate 1a, or a resist solution may be applied to the substrate surface S of the piezoelectric substrate 1a using a dispenser or coater and dried. Then, a resist film may be formed.

Next, in a pattern forming step S3, as shown in FIG. 6C, a pattern of the photosensitive resin layer 6 is formed. For example, the photosensitive resin layer 6 is removed from the region where the electrode terminals and electrode wiring for electrical connection with the external drive circuit are installed. For the pattern of the photosensitive resin layer 6, the photosensitive resin layer 6 is removed from a predetermined area through a photolithography process. The pattern forming step S3 can be omitted if it is not necessary to form a groove pattern or an electrode pattern on the substrate surface S of the piezoelectric substrate 1a.

Next, in the groove forming step Sm, as shown in FIG. 6D, the substrate surface S of the piezoelectric substrate 1a is ground by using a dicing blade D, a diamond cutter or the like to form a plurality of grooves 5. The grooves 5 are formed by alternately forming ejection grooves 5a for ejecting droplets and non-ejection grooves 5b that do not eject droplets. The ejection groove 5a is formed straight from the front end surface Fp of the piezoelectric substrate 1a to the front side of the rear end surface Bp, and the non-ejection groove 5b is formed straight from the front end surface Fp of the piezoelectric substrate 1a to the rear end surface Bp (FIG. 6D). 8). Note that FIG. 6D shows a cross section of a region different from that in FIG. 6C. FIG. 6C is a schematic cross-sectional view of a region where electrode terminals and electrode wirings are installed on the substrate surface S, and FIG. 6D is a region where a plurality of grooves 5 are formed, and a direction intersecting each groove 5. FIG. The width of the groove 5 is several 10 μm to 100 μm, the depth of the groove 5 is 300 μm to 400 μm, and the length of the groove 5 is 1 mm to several mm. When the chevron-type piezoelectric substrate 1a is used, the groove 5 is ground so that the position of the polarization boundary Z is approximately ½ of the depth of the groove 5. The grooves 5 are formed by several hundreds or more. The width (thickness) of the side wall 9 between the grooves 5 is several tens of μm to 100 μm.

Next, in the first cleaning step Sx1, as shown in FIG. 6E, the exposed surface Ep of the piezoelectric substrate 1a is cleaned. Note that FIG. 6E is a schematic view of the state in which the piezoelectric substrate 1a is cleaned, viewed from the front of the substrate surface S. In the present embodiment, the exposed surface Ep of the piezoelectric substrate 1a is the side surface and the bottom surface of each groove 5, and the installation area of the electrode terminal and the electrode wiring. The cleaning method is the same as in the first or second embodiment. That is, the plurality of piezoelectric substrates 1a are fixed to the substrate holder H, and the ends of the support arms N connected to the substrate holder H are connected to the vibration generator M. The cleaning tank Ba is filled with the cleaning liquid 2, for example, pure water, and the plurality of piezoelectric substrates 1a are dipped in the cleaning liquid 2 with the longitudinal direction of the groove 5 oriented vertically. Then, the vibration generator M is driven to vertically vibrate the support arm N at the second low frequency f2 having a frequency of 20 Hz to 400 Hz for 1 to 5 minutes. Therefore, each piezoelectric substrate 1a vibrates in the cleaning liquid 2 at the second low frequency f2 having a frequency of 20 Hz to 400 Hz in the vertical direction, that is, in the longitudinal direction of the groove 5.

As a result, the grinding powder and bubbles generated in the groove forming step Sm and adhering to the side surfaces and the bottom surface of the groove 5 or the crystal grain boundaries and the crystal grains whose bonding force is weakened by the grinding of the groove 5 are removed from the exposed surface Ep. can do. As described above, it is preferable that the second low frequency f2 has a smaller frequency F as the diameter R of the object to be cleaned is larger, and a frequency F is larger as the diameter R of the object to be cleaned is smaller. In this embodiment, since the piezoelectric substrate 1a vibrates in the longitudinal direction of the groove 5, the vibration of the cleaning liquid 2 is transmitted to the inside of the groove 5 and the foreign matter attached to the exposed surface Ep can be effectively removed. Further, the relative vibration energy of the cleaning liquid 2 is smaller than that in the ultrasonic cleaning, and the groove structure is not cracked.

Next, in the degreasing step S4, the exposed surface Ep of the piezoelectric substrate 1a is converted into a hydrophilic surface. The substrate holder H shown in FIG. 6E is degreased with pure water, water containing a surfactant, an organic solvent, or the like. For example, the exposed surface Ep of the piezoelectric substrate 1a is converted into a hydrophilic surface by immersing it in water containing a surfactant. As a result, it is possible to suppress the generation of a region in which the etching solution is not supplied and the etching becomes defective in the next etching step S5.

Next, in the etching step S5, as shown in FIG. 7A, the exposed surface Ep is etched and roughened to improve the adhesion strength of the plating film 4 generated in the electroless plating. For example, the piezoelectric substrate 1a is immersed in an etching solution of an ammonium fluoride aqueous solution having a concentration of 1.5%, and the PZT ceramics on the exposed surface Ep are softly (lightly) etched to form irregularities on the exposed surface Ep. The exposed surface Ep of the piezoelectric substrate 1a is uniformly and lightly etched, but crystal grains do not drop off and the strength of the upper portion of the side wall 9 does not decrease, and the adhesion strength of the plating film 4 to be formed later is improved. be able to.

Next, in the second cleaning step Sx2, as shown in FIG. 6E, the exposed surface Ep of the piezoelectric substrate 1a is cleaned. The cleaning method is the same as in the first cleaning step Sx1. That is, the plurality of piezoelectric substrates 1a are fixed to the substrate holder H, and the ends of the support arms N connected to the substrate holder H are connected to the vibration generator M. The cleaning bath Ba is filled with the cleaning liquid 2, for example, pure water, and the plurality of piezoelectric substrates 1 a are immersed in the cleaning liquid 2. Then, the vibration generator M is driven to vibrate the support arm N in the vertical direction at the second low frequency f2 having a frequency of 20 Hz to 400 Hz, preferably 50 Hz to 150 Hz. Therefore, each piezoelectric substrate 1a is vibrated in the cleaning liquid 2 at the second low frequency f2 having a frequency of 20 Hz to 400 Hz, preferably 50 Hz to 150 Hz, in the vertical direction, that is, in the longitudinal direction of the groove 5 for 1 to 5 minutes. It is possible to remove the small pieces of PZT ceramics generated by the etching process, the crystal grain boundaries and the crystal grains with weak bonding force from the exposed surface Ep.

Next, in the acid treatment step S6, the exposed surface Ep of the piezoelectric substrate 1a is acid-treated, for example, immersed in a nitric acid solution or an acetic acid solution. Lead contained in the piezoelectric substrate 1a acts as a catalyst poison. In the electroless plating step Sy, a plating catalyst is attached to the exposed surface Ep to accelerate the plating reaction, but the presence of a catalyst poison on the exposed surface Ep reduces the action of the plating catalyst. Therefore, the exposed surface Ep of the piezoelectric substrate 1a is immersed in an acidic solution to reduce the action of the catalyst poison.

Next, in the catalyst attachment step S7, as shown in FIG. 7B, the plating catalyst 7 is attached to the exposed surface Ep of the piezoelectric substrate 1a. As a method of attaching the plating catalyst 7, a sensitizer/activator method, a catalyst/accelerator method, or the like can be used. In the sensitizer activator method, first, the piezoelectric substrate 1a is dipped in an aqueous solution of stannous chloride (first step), and subsequently, dipped in an aqueous solution of palladium chloride (second step) to form a plating catalyst on the exposed surface Ep. Attach the palladium catalyst as 7. That is, metallic palladium is attached to the exposed surface Ep by the redox reaction of tin chloride and palladium chloride. The amount of metal palladium deposited can be increased by repeating the first step and the second step. Further, in the catalyst accelerator method, the piezoelectric substrate 1a is immersed in a colloidal solution of tin and palladium. Then, the piezoelectric substrate 1a is immersed in an acidic solution, for example, a hydrochloric acid solution to be activated, and metallic palladium is deposited on the exposed surface Ep.

Next, in the electroless plating step Sy, as shown in FIG. 7C, the plating film 4 is formed on the exposed surface Ep to which the plating catalyst is attached by the electroless plating method. The plating film 4 of Ni, Cr, Ag, Au or the like can be formed by the electroless plating method. For the electroless plating, the device shown in FIG. 6(e) can be used. That is, it is possible to form the plating film 4 while immersing the piezoelectric substrate 1a in the electroless plating solution 3 and vibrating the piezoelectric substrate 1a at the first low frequency f1 of 10 Hz to 200 Hz, preferably 40 Hz to 100 Hz. Specifically, the plurality of piezoelectric substrates 1a are fixed to the substrate holder H, and the ends of the support arms N connected to the substrate holder H are connected to the vibration generator M. The plating bath Bb is filled with the electroless plating solution 3, and the plurality of piezoelectric substrates 1 a are dipped in the electroless plating solution 3 with the longitudinal direction of the groove 5 oriented vertically. Then, after a lapse of a predetermined time, for example, 1 to 5 minutes, the vibration generator M is driven to vertically vibrate the support arm N at a first low frequency f1 of 10 Hz to 200 Hz, preferably 40 Hz to 100 Hz for a predetermined time. .. Therefore, each piezoelectric substrate 1a vibrates vertically in the electroless plating solution 3 at the first low frequency f1 having a frequency of 10 Hz to 200 Hz, preferably 40 Hz to 100 Hz, that is, in the longitudinal direction of the groove 5.

After the piezoelectric substrate 1a is immersed in the electroless plating solution 3, the piezoelectric substrate 1a is vibrated after a predetermined time elapses, so that the plating catalyst 7 attached to the exposed surface Ep is prevented from peeling off due to the vibration of the piezoelectric substrate 1a. You can Further, due to the vibration of the piezoelectric substrate 1a, a new electroless plating solution 3 is supplied inside the groove 5, and it is possible to reduce uneven thickness of the plating film 4 deposited on the inner surface (side surface and bottom surface) of the groove 5. .. Further, it is possible to prevent the gas generated during the plating reaction from adhering to the inner surface of the groove 5 or the opening.

Next, in the photosensitive resin layer removing step S8, as shown in FIG. 7D, the photosensitive resin layer 6 on the piezoelectric substrate 1a is removed to form a pattern of the plating film 4. The plating film 4 is not formed on the substrate surface S of the piezoelectric substrate 1a on which the photosensitive resin layer 6 is installed, and the plating film 4 is formed on the exposed surface Ep on which the photosensitive resin layer 6 is not installed. In this embodiment, the plating film 4 remains on the inner surface of the groove 5 and the region of the electrode terminal 11 on the substrate surface S (see FIG. 8).

Next, in the head assembly step Sz, as shown in FIG. 8, the cover plate 12 is bonded to the substrate surface S of the piezoelectric substrate 1a, and the nozzle plate 13 is attached to the front end face FP of the piezoelectric substrate 1a and the cover plate 12. The liquid jet head 10 is formed by bonding.

As shown in FIG. 8, the piezoelectric substrate 1a includes ejection grooves 5a and non-ejection grooves 5b that are alternately arranged on the substrate surface S. The plating film 4 deposited by the above method is provided on the inner surfaces of the ejection groove 5a and the non-ejection groove 5b. The plating film 4 on one side surface of the non-ejection groove 5b and the plating film 4 on the other side surface are electrically separated. After the plating film 4 is formed on the inner surface of the non-ejection groove 5b by the electroless plating method, for example, the bottom surface of the non-ejection groove 5b is irradiated with laser light to remove the plating film 4 on the bottom surface. The plating film 4 and the plating film 4 on the other side surface can be electrically separated. The piezoelectric substrate 1a includes individual electrode terminals 11b on the rear end face Bp side of the substrate surface S, and common electrode terminals 11a in front of the individual electrode terminals 11b. The individual electrode terminal 11b electrically connects the plating film 4 on the ejection groove 5a side of the two non-ejection grooves 5b adjacent to each other with the ejection groove 5a interposed therebetween. The common electrode terminal 11a is electrically connected to the plating film 4 of the ejection groove 5a.

The cover plate 12 is formed on the substrate surface S of the piezoelectric substrate 1a such that the front end face Fp is flush with the front end face Fp of the piezoelectric substrate 1a and the common electrode terminals 11a and the individual electrode terminals 11b are exposed. To be glued. The cover plate 12 has a liquid supply chamber 12a on the rear side, and the liquid supply chamber 12a has a slit 12b penetrating from the bottom surface thereof to the piezoelectric substrate 1a side. The slit 12b connects the liquid supply chamber 12a and the rear end of the ejection groove 5a, and supplies the liquid from the liquid supply chamber 12a to the ejection groove 5a. The nozzle plate 13 is bonded to the front end face Fp of the piezoelectric substrate 1a and the cover plate 12. The nozzle plate 13 includes a nozzle 13a, and the nozzle 13a communicates with the ejection groove 5a.

The liquid jet head 10 operates as follows. First, the liquid is supplied to the liquid supply chamber 12a, and the ejection groove 5a is filled with the liquid via the slit 12b. Then, a drive signal is applied to the common electrode terminal 11a and the individual electrode terminal 11b to cause the side walls 9 that sandwich the ejection groove 5a to undergo thickness-slip deformation. Specifically, the side walls 9 are deformed in the direction in which the volume of the ejection groove 5a is expanded to draw the liquid from the liquid supply chamber 12a into the ejection groove 5a, and then the side walls in the direction in which the volume of the ejection groove 5a is reduced. 9 is deformed and droplets are ejected from the nozzle 13a. The liquid jet head 10 shown in FIG. 8 is an example. The method for manufacturing a liquid jet head of the present invention can be applied to a side shoot type or a liquid circulation type liquid jet head as well as an edge shoot type liquid jet head.

1 substrate 1a piezoelectric substrate 2 cleaning liquid 3 electroless plating liquid 4 plating film 5 groove 5a discharge groove 5b non-discharge groove 6 photosensitive resin layer 7 plating catalyst 9 side wall 10 liquid jet head 11 electrode terminal, 11a common electrode terminal , 11b individual electrode terminal 12 cover plate, 12a liquid supply chamber, 12b slit 13 nozzle plate, 13a nozzle f1 first low frequency, f2 second low frequency, M vibration generator, N support arm H substrate holder, Ba cleaning Bath, Bb plating bath, S substrate surface, Ep exposed surface Z polarization boundary, Fp front end face, Bp rear end face

Claims (8)

A cleaning process of cleaning the substrate by immersing it in a cleaning liquid;
The substrate is immersed in an electroless plating solution and the substrate is vibrated in a direction parallel to the exposed surface of the substrate at a low frequency of 10 Hz to 200 Hz (excluding 10 to 60 Hz and 100 to 200 Hz) . An electroless plating step of forming a plating film on the exposed surface. The plating film forming method according to claim 1, wherein the cleaning step is a step of immersing the substrate in the cleaning liquid and vibrating the substrate at a low frequency of 20 Hz to 400 Hz to clean the substrate. A groove forming step of forming a plurality of grooves in parallel on the piezoelectric substrate,
A cleaning step of cleaning the piezoelectric substrate by immersing the piezoelectric substrate in a cleaning liquid,
The piezoelectric substrate is immersed in an electroless plating solution, and the piezoelectric substrate is vibrated in a direction parallel to the exposed surface of the substrate at a low frequency of 10 Hz to 200 Hz (excluding 10 to 60 Hz and 100 to 200 Hz). And an electroless plating step of forming a plating film on the exposed surface of the piezoelectric substrate. The method of manufacturing a liquid jet head according to claim 3 , wherein the cleaning step is a step of immersing the piezoelectric substrate in the cleaning liquid and vibrating the piezoelectric substrate at a low frequency of 20 Hz to 400 Hz for cleaning. The method of manufacturing a liquid jet head according to claim 3 , wherein the electroless plating step includes a step of vibrating the piezoelectric substrate in a longitudinal direction of the groove to form the plating film. The washing step, the method of manufacturing the liquid jet head according to the piezoelectric substrate in any one of claims 3-5 is a step of washing by vibrating in the longitudinal direction of the groove. A first cleaning step of cleaning the exposed surface of the piezoelectric substrate by the cleaning step;
An etching step of etching the exposed surface of the piezoelectric substrate,
A second cleaning step of cleaning the exposed surface of the piezoelectric substrate by the cleaning step;
Method of manufacturing a liquid jet head according to any one of claims 3-6; and a catalyst adhering step of adhering a plating catalyst on the exposed surface of the piezoelectric substrate before the electroless plating step. A photosensitive resin layer forming step of installing a photosensitive resin layer on the surface of the piezoelectric substrate before the groove forming step;
Method of manufacturing a liquid jet head according to any one of claims 3-7, wherein the photosensitive resin layer removing step of removing the photosensitive resin layer after the electroless plating step, further comprising a.

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