KR100403580B1 - A printhead structure of ink-jet printer - Google Patents

Abstract

The present invention relates to a print head structure of an ink jet printer. The print head of the present invention has a structure in which at least two substrates not provided with a separate manifold are separated from each other by a predetermined interval, and bonded to a flexible printed circuit board serving as a nozzle plate, wherein the spaces at the predetermined intervals are spaced apart from the manifold. Play a role. Since the print head of the present invention does not have a separate manifold penetrating the substrate, the process necessary for forming the manifold is unnecessary and the mechanical strength can be prevented from being weakened by the manifold. Further, in a preferred embodiment, the leads of the flexible printed circuit board and the bonding pads of the substrate are bonded using solder balls or solder bumps, thereby eliminating the need for openings required for conventional ultrasonic welding. Therefore, the sealing of the opening by the silicon bond after bonding is unnecessary, thereby simplifying the process and ensuring high resolution printing.

Description

A printhead structure of ink-jet printer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head structure of an ink jet printer, and more particularly to a coupling structure of a substrate and / or ink cartridge having a plurality of ink ejecting portions formed thereon and a flexible printed circuit board.

In general, ink jet printers have print heads as their core components. In the present specification, the print head refers to a combination of a substrate on which a plurality of ink ejecting portions are formed and a flexible printed circuit board on which circuits for driving and controlling each ink ejecting portion are implemented. That is, the assembly of the substrate 20 and the flexible printed circuit board 30 shown in the upper portion of FIG. 1 is referred to as a print head. The print head is attached to the ink cartridge 10 containing the ink, as shown in FIG. 1, and exchanges electrical signals with the printer body through the contact pads 36.

FIG. 2 is a plan view illustrating a bubble jet printhead in which a substrate 20 and a flexible printed circuit board 30 are coupled, and FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2. Referring to Figures 2 and 3 will be described in the general structure of the print head and the coupling structure of the ink cartridge.

First, the heater plate 25 for generating bubbles is formed on the surface of the substrate 20, and the nozzle plate 23 having the nozzle 24 formed on the upper portion of the space (ink chamber) defined by the heater 25. ) Is attached on top of the substrate 20. In addition, an ink supply manifold 22 for supplying ink from the ink cartridge 10 under the substrate 20 to each ink chamber is formed penetrating from the rear surface of the substrate 20 to the surface. The substrate 20 to which the nozzle plate 23 is attached is attached to the substrate mounting groove 14 of the ink cartridge 10 by the adhesive agent 50. Therefore, the ink supplied through the ink supply port 12 in the ink cartridge 10 is supplied and discharged in the path as indicated by the arrow in FIG.

On the other hand, each bonding pad 26 of the substrate 20 is bonded to the lead 32, which is the end of the wiring 34 of the flexible printed circuit board 30 by ultrasonic welding. For ultrasonic fusion between the lead 32 made of copper and the bonding pad 26 made of aluminum, a lead portion, which is a part of the polyimide film 31 of the flexible printed circuit board 30, that is, a portion where ultrasonic fusion is performed ( Or bonding portion) should be opened as indicated by reference numeral 35 in FIGS. 2 and 3. After ultrasonic welding, this open opening 35 is sealed with a silicon bond 40.

In the substrate 20 having such a structure, since the manifold 22 is formed through the substrate 20, it takes not only a long time to form the manifold 22 but also the mechanical weakness and the substrate with a slight impact. There is a problem that 20 is split around the manifold 22. In addition, the silicon bond 40 which seals the opening 35 after ultrasonic welding of the lid portion protrudes from the surface of the print head to a predetermined thickness, as shown in FIG. 3, thereby preventing close contact with printing paper for high resolution printing. do.

Meanwhile, in order to improve the mechanical weakness caused by the manifold 22 as described above, US Patent No. 5,278,584 does not form a manifold, but a plurality of ink ejecting portions are formed along both sides of the substrate, and ink is deposited on both sides of the substrate. It takes a structure to be supplied. In addition, this patent does not have a nozzle plate separately, and a nozzle is drilled directly to a flexible printed circuit board, and serves as a nozzle board and a flexible printed circuit board. However, this patent still has a structure to form an opening for opening the lead portion of the flexible printed circuit board for ultrasonic welding of the lead and the bonding pad, and to seal with silicon bond after ultrasonic welding, thereby limiting high resolution printing.

The technical problem to be achieved by the present invention is to provide a print head with sufficient mechanical strength.

It is an object of the present invention to provide a print head capable of high resolution printing.

1 is a perspective view showing a coupling relationship between an ink cartridge and a print head of a conventional ink jet printer.

FIG. 2 is a plan view of a portion of the print head of FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2.

4 is a perspective view illustrating a state in which a flexible printed circuit board and a substrate are coupled according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4.

6 is a perspective view showing in detail the process of assembling the print head according to an embodiment of the present invention.

7 is a perspective view showing a relationship in which the print head according to another embodiment of the present invention is assembled.

8 is a perspective view showing a relationship in which the print head according to another embodiment of the present invention is assembled.

The print head according to the present invention for achieving the above technical problem, has a structure bonded to a flexible printed circuit board at least two substrates that do not have a separate manifold serves as a nozzle plate. That is, each of the at least two substrates includes a plurality of ink ejecting portions and bonding pads, and does not include a separate manifold, and is disposed at predetermined intervals, and the flexible printed circuit board is formed on the flexible polymer film. And a plurality of leads bonded to the plurality of bonding pads of the substrate, respectively, nozzles corresponding to the plurality of ink ejecting portions of the substrate, and wirings for driving the plurality of ink ejecting portions. . The at least two substrates and the flexible printed circuit board are bonded through the leads and the bonding pads, and the spaces spaced apart from the predetermined intervals serve as manifolds.

Here, a solder ball or solder bump is formed in the lead of the flexible printed circuit board, and the lead and the bonding pad are preferably bonded through the solder ball or the solder bump.

As such, the print head of the present invention does not have a separate manifold penetrating the substrate, thereby ensuring sufficient mechanical strength. Further, in a preferred embodiment, the leads of the flexible printed circuit board are provided with solder balls or solder bumps and bonded with the bonding pads through them, thus eliminating the need for openings required for conventional ultrasonic welding, and thus by bonding with silicon bonds. No opening sealing is required, which simplifies the process and ensures high resolution printing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the examples exemplified below are not intended to limit the scope of the present invention, but are provided to fully explain the present invention to those skilled in the art. The same reference numerals in the drawings refer to the same, the thickness or size of each element in the drawings may be exaggerated for convenience and clarity of description. Incidentally, in the following description, the vertical relationship between the substrate and the flexible printed circuit board will be described based on the positional relationship on the drawings. However, in a specific embodiment, the vertical relationship may be changed.

4 is a perspective view illustrating a structure of a print head and a coupling relationship between the substrates 120a and 120b and the flexible printed circuit board 130 according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating the substrate 120a and 120b. 4 is a cross-sectional view taken along line 5-5 of FIG.

First, a plurality of ink ejecting portions are formed in each of the two substrates 120a and 120b according to the present embodiment. Specifically, heaters 125 for generating bubbles are formed on the surfaces of the substrates 120a and 120b, and barriers 127 are formed on the left and right sides of the heaters 125 to form respective ink chambers. It is. In addition, wirings to which electrical signals for driving and controlling the respective ink ejecting portions are applied, and bonding pads 126 and 126 'connected to the ends of the wirings are formed. Here, the wiring and the bonding pads 126 and 126 'are simultaneously formed of a metal such as aluminum, for example. As shown, a separate manifold (see 22 in FIGS. 2 and 3) is not formed on the substrates 120a and 120b of the print head of this embodiment.

In the flexible printed circuit board 130, wirings 134 and 134 'made of copper, for example, are formed on the bottom of the flexible polymer film, for example, the polyimide film 131, and the end of each wiring 134 is a printer body. It is connected to the contact pad 136 is connected to. In addition, an end opposite to the contact pad 136 of each wiring 134 forms a lead 132 bonded to the bonding pads 126 of the substrates 120a and 120b. Solder balls or solder bumps 133 are formed on the bottoms of the leads 132 and 132 '. The solder balls or solder bumps 133 may be formed of lead or lead-tin alloy through a gold film on the bottom of the leads 132 and 132 'made of copper, and beneath the leads 132 and 132' made of copper. It can also be formed directly from gold. In addition, the flexible polymer film 131 of the flexible printed circuit board 130 of the present embodiment is not formed with an opening (see 35 in FIGS. 2 and 3) for ultrasonic welding, and is formed in the substrates 120a and 120b. The nozzle 124 is formed at a position corresponding to the center of the ink chambers of the plurality of ink ejecting portions, such that the flexible printed circuit board 130 also serves as a nozzle plate.

The substrates 120a and 120b and the flexible printed circuit board 130 are bonded by bonding the solder balls or the solder bumps 133 and the bonding pads 126. The substrates 120a and 120b and the flexible printed circuit board 130 are combined. ), That is, the print head is attached to the substrate mounting groove 14 of the ink cartridge by the adhesive 50 to complete the assembly.

As described above, the print head of the present embodiment does not have a separate manifold, and a space between two substrates 120a and 120b coupled at a predetermined interval serves as a manifold, and the ink supply port 12 in the ink cartridge 10 is provided. The ink supplied through) is supplied and discharged through a path as indicated by an arrow in FIG. 5.

On the other hand, in order to control the respective ink ejecting portions, the substrate may need wirings connecting all of the ink ejecting portions such as an address line. However, in the present exemplary embodiment, the substrates 120a and 120b are separated from each other so that a connection line such as an address line cannot be connected on the substrates 120a and 120b. Therefore, in the present embodiment, a connection line 134 'like this address line is formed on the flexible printed circuit board 130, not on the substrates 120a and 120b, and the lead 132' and the bonding pad 126 'are therefor. ) Are formed on the flexible printed circuit board 130 and the substrates 120a and 120b, respectively. Therefore, there is no problem in the control of the ink ejection portion even when two separate substrates 120a and 120b are used.

Next, a method of assembling the print head according to the preferred embodiment of the present invention will be described in detail.

First, the substrates 120a and 120b are prepared. The substrates 120a and 120b have different structures and manufacturing methods according to specific applications, and the structure or manufacturing method of the substrates 120a and 120b itself is irrelevant to the features of the present invention, and thus detailed description thereof will be omitted. However, in the present invention, since it is not necessary to form the manifold on the substrates 120a and 120b, there is no need to perform a process such as etching or sand blasting to form the manifold, and each ink ejecting portion After the wiring and the bonding pads 126 are formed, the preparation of the substrates 120a and 120b is completed through a sawing process of separating and cutting the wafer for each substrate.

The flexible printed circuit board 130 is also subjected to a conventional process to form leads 132 and 132 ′, wirings 134 and 134 ′, and contact pads 136 on the flexible polymer film 131, and the nozzle 124. By drilling).

However, in the present exemplary embodiment, the solder ball or the solder bumps 133 are formed on the bottom of the lead. This can be formed in various ways. For example, when solder balls are formed, the leads 132 and 132 'are formed on the polymer film 131 (the flexible printed circuit board 130 of FIG. 5 is turned upside down). ), The wirings 134, 134 ′ and the contact pads 136 are formed, and then the leads 132, 132 ′ are subjected to surface treatment (for example, gold plating), and the solder balls are picked up to form the leads 132, 132 ') and then apply by applying some heat and / or ultrasound. In the case of solder bumps, the leads 132 and 132 ', the wirings 134 and 134', and the contact pads 136 may be formed on the polymer film 131, and then solder bumps may be formed by screen printing. . That is, after aligning the mask having a hole formed in the portion to form the solder bump on the flexible printed circuit board 130, the conductive metal paste is applied to the entire surface and the mask is removed to form a solder bump. Alternatively, the solder balls or solder bumps may be formed by ball bonding gold wires to the leads 132 and 132 ′ through a wire bonding process, and then cutting the neck of the bonded balls. In addition, the process of forming the solder balls or the solder bumps 133 may be modified in various ways with respect to the method and order of forming the leads 132 and 132 ', the wirings 134 and 134', and the contact pads 136. Can be.

In addition, in the present embodiment, the lead portion (or bonding portion) of the flexible polymer film 131 does not need to form an opening (see 35 in FIGS. 2 and 3) for ultrasonic welding, and thus a punching or etching process for this purpose. Do not go through.

Subsequently, the substrates 120a and 120b thus prepared and the flexible printed circuit board 130 are bonded by bonding. Specifically, as shown in FIG. 6, a plurality of flexible printed circuit boards 130 are bonded by arranging and bonding the substrates 120a and 120b one by one on a film connected in tape form. That is, while moving the flexible printed circuit board 130 tape, the substrates 120a and 120b are placed so that the bonding pads 126 and the solder balls or the solder bumps 133 face each other, for example, a temperature of about 250 to 300 ° C. Passing through the infrared oven maintained at, the solder balls or solder bumps 133 melt and bond with the bonding pads 126. In FIG. 6, the substrates 120a and 120b are placed one by one, but two substrates may be placed at the same time.

In this way, the plurality of flexible printed circuit boards 130 bond the substrates 120a and 120b onto a film connected in a tape form, and then cut each print head unit, and as shown in FIG. 5, each ink cartridge 10. The assembly of the print head and the ink cartridge 10 is completed by attaching to the board | substrate mounting groove 14 of () using the adhesive agent 50. FIG.

Meanwhile, in the above-described bonding process, as in the other embodiment of the present invention illustrated in FIG. 7, six substrates 120a to 120f are first attached to the ink cartridge 10 in pairs for each color. It may be achieved by bonding the flexible printed circuit board 130 'to the assembly of the substrates 120a to 120f and the ink cartridge 10. In this case, the material of the ink cartridge 10 may be a temperature at the time of bonding as described above. It is preferably made of a material such as heat resistant plastic that can withstand it.

8 is a perspective view illustrating a process of assembling a print head according to another embodiment of the present invention. In this embodiment, the bonding between the substrates 120a and 120b and the flexible printed circuit board 130 " For this purpose, the flexible printed circuit board 130 ″ is formed with an opening 135 for ultrasonic welding, and the leads 132 and 132 ′ are solder balls or solder bumps as in the above-described embodiments. There is no need to form 133. On the other hand, after bonding the leads 132 and 132 'and the bonding pad 126 by ultrasonic welding, it is necessary to seal the opening 135 using a silicon bond or the like.

Although specific embodiments of the present invention have been described in detail using specific structures and terms, the present invention is illustrative, and various modifications of the present invention are possible. For example, the substrates 120a to 120f shown in the above-described embodiments and drawings may have ink ejection portions of various structures depending on the application. In addition, although the nozzle 124 is described as being formed in the process of preparing the flexible printed circuit boards 130, 130 ′, and 130 ″ in the above-described embodiments and drawings, the substrates 120a to 120f and the flexible printed circuit board are described. (130, 130 ', 130 ") may be drilled after bonding.

As described in detail above, the print head according to the present invention does not form a manifold penetrating the substrate on the substrate, but forms a manifold by utilizing the space between two substrates arranged at a predetermined interval as a manifold. The process is not necessary, and the mechanical strength can be prevented from weakening due to the manifold. Thus, productivity and yield are increased and the life of the print head is increased.

In addition, according to an embodiment of the present invention, by bonding the bonding pads of the substrate and the leads of the flexible printed circuit board through solder balls or solder bumps, it is necessary to form openings necessary for conventional ultrasonic welding in the flexible printed circuit board. There is no need to seal the openings with silicon bonds after bonding. Therefore, it is more suitable for high resolution printing.

Claims (4)

At least two substrates each having a plurality of ink ejecting portions and bonding pads, and not having a separate manifold, disposed at predetermined intervals; And The flexible polymer film includes a plurality of leads bonded to each of the plurality of bonding pads, a nozzle corresponding to each of the plurality of ink ejecting portions is formed, and wires for driving the plurality of ink ejecting portions are formed. Including sex printed circuit board, And the flexible printed circuit board is bonded through the leads on the at least two substrates, and the spaces spaced apart by the predetermined intervals serve as manifolds. The method of claim 1, Each of the at least two substrates includes at least one connection wiring bonding pad connected to a wiring connecting a plurality of ink discharge parts formed on each substrate, The flexible printed circuit board, At least two connection wiring leads bonded to the at least one connection wiring bonding pad formed on each of the at least two substrates; And And a wiring connecting the at least two connection wiring leads to each other. The inkjet printer of claim 1, wherein solder leads or solder bumps are formed on the leads of the flexible printed circuit board, and the leads and bonding pads are bonded through the solder balls or solder bumps. Head structure. The ink of claim 1, wherein an opening for ultrasonic welding is formed at a portion of the flexible polymer film to which the lead and the bonding pad are bonded, and the lead and the bonding pad are bonded by ultrasonic welding. Printhead structure of a jet printer.