Patent Publication Number: US-11648581-B1

Title: Method for manufacturing a material dispense tip

Description:
RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 16/775,666, filed Jan. 29, 2020, now U.S. Pat. No. 11,292,025, issued on Apr. 5, 2022, which is a continuation application of U.S. patent application Ser. No. 15/292,427, filed Oct. 13, 2016, now U.S. Pat. No. 10,583,454, issued on Mar. 10, 2020, which is a continuation application of U.S. patent application Ser. No. 14/217,809, filed Mar. 18, 2014, now U.S. Pat. No. 9,486,830, issued on Nov. 8, 2016, which is a continuation application of U.S. patent application Ser. No. 12/034,313, filed on Feb. 20, 2008, now U.S. Pat. No. 8,707,559, issued on Apr. 29, 2014, which claims the benefit of U.S. Provisional Patent Application No. 60/890,744 filed on Feb. 20, 2007, the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     A fluid dispense tip, also referred to as a “pin” or “needle,” is utilized in a variety of applications. For example, a fluid dispense tip, when attached to a fluid dispense pump system, is used to deposit a precise amount of fluid material, such as glue, resin, or paste, at precise positions on a semiconductor substrate. Examples of such fluid dispense pumps are described in U.S. Pat. No. 6,511,301, U.S. patent application Ser. No. 10/948,850, filed Sep. 23, 2004, entitled “Fluid Pump and Cartridge,” U.S. Pat. Nos. 6,892,959, 6,983,867, and U.S. patent application Ser. No. 10/810,236, filed Mar. 26, 2004, entitled “Dispense Pump with Heated Pump Housing and Heated Material Reservoir,” the contents of each being incorporated herein by reference in their entirety. 
     The increase in integration density in semiconductor devices has led to the need for dispense needles to deposit fluid materials onto a substrate with higher precision, requiring fluid materials to be deposited in the form of dots having small diameters or lines having narrow widths, or other dispense patterns. 
     Several approaches are used to form a dispense tip that can dispense fluid material patterns, such as dots or lines. In one conventional approach, a neck of a dispense tip is formed by rolling a flat portion of machined metal into a cylindrical form and sealing the edges of the rolled, machined metal. 
     In another conventional approach, similar to that disclosed in United States Patent Application Publication Serial No. 2003/0071149, the contents of which are incorporated by reference in their entirety, a dispense tip is formed by applying a conically-shaped mandrel against a malleable metallic disk and forcing the metal to be drawn down into a first cavity of a first die. The formed metal is removed from the first die. These steps are repeated using progressively smaller-diameter mandrels and progressively smaller-diameter circular dies until the finished dispense tip is formed. 
     In another approach, as disclosed in U.S. Pat. Nos. 6,547,167, 6,981,664, 6,957,783, the contents of which are incorporated herein by reference in their entirety, and as illustrated in  FIG.  1   , a body and a neck of a dispense tip are machined from a common stock, and a bore is drilled through the body and the neck, resulting in a bore in the neck having a relatively large constant first diameter that tapers down to an outlet having a relatively small second diameter. 
     In another approach, also disclosed in U.S. Pat. No. 6,547,167, the contents of which are incorporated herein by reference in their entirety, a dispense tip is molded or cast from materials such as plastics, composites, metals, or ceramics, other materials known to those of skill in the art as being used in the formation of a dispense tip. 
     As demands for dispensing precision continue to increase with the demand of further integration of devices, the above approaches have reached physical limits in their ability to provide dispense tips with outlets smaller than those achievable by the smallest available machining tools or die casts. This limits the ability to control dispensing operations of material at such fine dimensions and volumes. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to dispense tips and methods of manufacturing the same, which overcome the limitations associated with the aforementioned approaches. 
     In accordance with an aspect of the invention, a method of forming an outlet hole in a material dispense tip suitable for low-volume material dispensing operations, the dispense tip having an elongated neck and an elongated hole in the neck extending from an input end of the neck to an output end of the neck, the hole at the output end of the neck having a first diameter comprises positioning the output end of the neck against a die surface; inserting a punch into the hole at the input end of the neck; and applying an external force to the neck to cause the output end of the neck to deform under compression by the die surface, to reduce the diameter of the hole at the output end of the neck from the first diameter to a second diameter that is less than the first diameter. 
     In an embodiment, the output end of the neck is positioned in an indentation of the die surface. 
     In an embodiment, the shape of the indentation is a V-shaped cone. 
     In an embodiment, the indentation is a female impression, and a diameter of a top portion of the female impression at the surface of the die is about 0.040 inches, and the depth of the female impression is about 0.020-0.040 inches. 
     In an embodiment, the shape of the indentation is parabolic. 
     In an embodiment, a geometry of the outlet hole is determined by the shape of the indentation. 
     In an embodiment, the neck is along a vertical axis, and wherein the external force is applied to the male punch in a downward direction along the vertical axis. 
     In an embodiment, the method further comprises forming an inlet hole from the input end of the neck to the outlet hole, the inlet hole having a third diameter that is greater than the first and second diameters at the output end of the neck. 
     In an embodiment, the method further comprises forming a taper between the inlet hole and the outlet hole that transitions that inlet hole having the third diameter to the second diameter of the outlet hole. 
     In an embodiment, a continuous fluid path is formed from the inlet hole at the input end of the neck to the outlet hole. 
     In accordance with another aspect, a dispense tip comprises an elongated neck; an elongated hole in the neck extending from an input end of the neck to an output end of the neck, the hole having a first diameter; and an outlet hole in a portion of the elongated hole at the output end of the neck, the outlet hole comprising a first end having the first diameter and second end that is deformed under compression such that an opening at the second end of the outlet hole has a second diameter that is less than the first diameter of the first end. 
     In an embodiment, the tip further comprises a first inner taper between the hole at the input end of the neck and the first end of the outlet hole. 
     In an embodiment, the outlet hole comprises a second inner taper between the first end of the outlet hole and the second end of the outlet hole. In an embodiment, the second inner taper is formed by positioning the output end of the neck against a die surface and applying an external force to the neck. 
     In an embodiment, the external force is a controlled force that is applied to a punch that is inserted into the input end of the neck. 
     In an embodiment, a base is coupled to the input end of the neck. In an embodiment, the base and the neck are unitary, and the base and the neck are formed from a single stock. In another embodiment, the base and the neck are independently formed, and coupled together by coupling the neck to the base. In an embodiment, the base comprises a LUER™-type coupling. 
     In accordance with another aspect, a method of forming a dispense tip comprises forming a neck having an input end and an output end on a longitudinal axis; forming a first hole in the neck centered along the longitudinal axis, the first hole having a first diameter from the input end of the neck to the output end of the neck; forming a second hole in the output end of the neck centered along the longitudinal axis, the second hole having a second diameter that is less than the first diameter; positioning the output end of the neck against a die surface; inserting a punch into the first hole of the neck; and forming an outlet hole from a portion of the second hole at the output end of the neck by applying an external force to the neck, the outlet hole comprising a first end having the second diameter and an opening at a second end having a third diameter that is smaller than the second diameter. 
     In an embodiment, the method comprises forming a first inner taper between the first hole and the second hole, the inner taper transitioning the first hole having the first diameter to the input end of the second hole having the second diameter. 
     In an embodiment, forming the outlet hole further comprises forming a second inner taper between the first end and the opening at the second end of the outlet hole. 
     In an embodiment, the second inner taper is formed by positioning the output end of the neck against a die surface and applying the external force to the dispense tip to reduce a diameter of the opening to the third diameter. 
     In an embodiment, the external force is a controlled force that is applied to a punch that is inserted into the first hole of the neck. 
     In an embodiment, the method comprises forming a first outer surface of the neck having a first outer diameter proximal to the input end of the neck and forming a second outer surface having a second outer diameter at the output end of the neck, and forming a first outer taper that transitions the first outer surface of the neck to the second outer surface of the neck. 
     In an embodiment, forming the first outer taper comprises beveling the neck along the longitudinal axis of the neck. 
     In an embodiment, the method comprises forming a second outer taper that transitions the second outer surface having the second outer diameter to a third outer surface proximal to the outlet, the third outer surface having a third outer diameter. 
     In an embodiment, the second outer taper is formed by positioning the tip of the output end of the neck against a die surface and applying an external force to the dispense tip. 
     In accordance with another aspect, a dispense tip comprises an outlet hole in a material dispense tip suitable for low-volume material dispensing operations, the dispense tip having an elongated neck and an elongated hole in the neck extending from an input end of the neck to an output end of the neck, the hole at the output end of the neck having a first diameter, and the outlet hole is formed according to a process including: positioning the output end of the neck against a die surface; inserting a punch into the hole at the input end of the neck; and applying an external force to the neck to cause the output end of the neck to be deformed under compression by the female die surface, to reduce the diameter of the hole at the output end of the neck from the first diameter to a second diameter that is less than the first diameter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages of the invention will be apparent from the more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG.  1    is an illustrative cross-sectional view of a machined dispense tip having a reduced-diameter outlet that is less than the inner diameter of a primary neck bore. 
         FIG.  2 A  is an illustrative cross-sectional view of a dispense tip in accordance with an embodiment of the present invention.  FIG.  2 B  is an enlarged partial cross-sectional view of an outlet hole region of the dispense tip neck of  FIG.  2 A . 
         FIGS.  3 A- 3 C  are cross-sectional views illustrating sequential steps of forming an outlet hole in the dispense tip of  FIGS.  2 A- 2 B , in accordance with embodiments of the present invention. 
         FIG.  4 A  is an illustrative cross-sectional view of a dispense tip in accordance with another embodiment of the present invention.  FIG.  4 B  is an enlarged partial cross-sectional view of the dispense tip neck of  FIG.  4 A . 
         FIG.  5    is an illustrative cross-sectional view showing an outlet hole of the dispense tip of  FIGS.  4 A- 4 B  being formed in accordance with an embodiment of the present invention. 
         FIGS.  6 A- 6 B  are illustrative cross-sectional views of a dispense tip formed by a combination of a separately machined neck being joined to a body in accordance with an embodiment of the present invention. 
         FIG.  7    is an illustrative cross-sectional view of a dispense tip having a LUER™-style body in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The accompanying drawings are described below, in which example embodiments in accordance with the present invention are shown. Specific structural and functional details disclosed herein are merely representative. This invention may be embodied in many alternate forms and should not be construed as limited to example embodiments set forth herein. 
     Accordingly, specific embodiments are shown by way of example in the drawings. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the claims. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “on,” “connected to” or “coupled to” another element, it can be directly on, connected to or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
       FIG.  1    is an illustrative cross-sectional view of a machined dispense tip  100  having a reduced-diameter outlet  140  that is less than the inner diameter of a primary neck hole  130 , in accordance with those described in U.S. Pat. No. 6,547,167, incorporated by reference above. 
     Referring to  FIG.  1   , the neck hole  130  is formed in a neck  110  and body  120  of the dispense tip  100 . The neck hole  130  has an inner diameter D 1 . The outlet hole  140  is formed in the neck  110  at an outlet end of the neck  110 . The outlet hole  140  has an inner diameter D 2  that is significantly smaller than the inner diameter D 1  of the neck hole  130 . An inner taper  150  transitions the neck hole  130  having the inner diameter D 1  to the outlet hole  140  having the smaller inner diameter D 2 . 
     In forming the dispense tip  100 , a primary neck hole  130  is machined, drilled, or otherwise formed through a proximal end  101 A of the dispense tip  100 , and through the body  120  and neck  110 , resulting in a neck hole  130  having an inner diameter D 1 . In one embodiment, the inner diameter D 1  is substantially constant along the length of the neck hole  130 . In another embodiment, the neck hole  130  comprises a taper or draft from the input end of the neck hole  130  to the outlet hole  140 , such that a diameter at an input end of the neck hole  130  is greater than a diameter at an output end of the neck hole  130  proximal to the outlet hole  140 . In another embodiment, the neck hole  130  comprises a taper or draft from the input end of the neck hole  130  to the inner taper  150 , such that a diameter at an input end of the neck hole  130  is greater than a diameter at the opposite side of the neck hole  130  near the inner taper  150 . 
     The outlet hole  140  is formed by machining, drilling, or otherwise forming an outlet bore through a distal end  101 B of the dispense tip  100 , for example, using a drill bit having a smaller inner diameter than the drill bit used to form the primary neck hole  130 . The resulting wider neck bore diameter D 1  along the majority of the neck  110  allows for delivery of fluid to the relatively narrow inner diameter D 2  opening at a relatively low pressure that is more desirable for volume control, while the relatively small outlet hole  140  allows for control over the volume and width of the dispensed fluid on the substrate. 
     However, the respective diameters D 2 , D 1  of the outlet hole  140  and neck hole  130  are dependent on the outer diameter of the drill bits used to form the outlet hole  140  and neck hole  130 . The dispense tip  100  illustrated in  FIG.  1    is therefore limited to an outlet bore diameter D 2  on the order of approximately 0.004 inches or more, since drilling at diameters less than this approaches the limits of what is possible using conventional tooling, or limited to diameters permitted by conventional molding techniques. The diameter of a dispensed dot pattern depends largely on the diameter of the outlet hole  140 . For example, an outlet hole diameter of 0.004 inches may result in a dispensed dot pattern having a diameter of approximately 0.006 inches. However, such a dot pattern diameter may be too large for certain modern applications. For example, as the trend of further circuit integration continues, the area of circuit components decreases, while pin count increases; thus, there is an increasing need for precise patterns, such as dot patterns, to be dispensed having very small diameters and volumes, but without sacrificing the accuracy and reliability of such dispensing operations. 
       FIG.  2 A  is an illustrative cross-sectional view of a dispense tip  200  in accordance with an embodiment of the present invention.  FIG.  2 B  is an enlarged partial cross-sectional view of an outlet hole region  201 B of the dispense tip neck  210  of  FIG.  2 A . 
     In the embodiment of  FIGS.  2 A- 2 B , the dispense tip  200  comprises a neck  210  and a body or base  220 . In one embodiment, the body  220  and neck  210  of the dispense tip  200  can be machined from a common stock, as shown in  FIG.  2 A . Such unitary construction provides a dispense tip that is of enhanced strength and rigidity, and therefore leads to more accurate and consistent dispensing, as well as greater longevity. The neck  210  and body  220  can be formed of a workable, machinable material such as stainless steel, for example, 303 stainless, or metals such as copper, brass, aluminum, or other metals, or alloys thereof, known to one or ordinary skill as possessing machining properties necessary to form a machined dispense tip. The neck  210  and body  220  can be also machined, molded, or otherwise formed from any number of applicable materials, including ceramics, composites, and plastics, or other materials known to one of ordinary skill as possessing machining or molding properties necessary to form a machined or molded dispense tip. Alternatively, as shown in  FIG.  6   , the neck  210  can be formed separately from the body  220 , and later joined to the body  220 , in which case the body  220  and neck  210  can be coupled together via press-fitting, bonding, or welding, or other applicable techniques. In other embodiments, the neck  210  or body  220  of the dispense tip  200  can be formed in accordance with methods similar to those disclosed in U.S. Pat. No. 6,547,167, incorporated by reference above. In other embodiments, the materials used to form the neck  210  and body  220  can be heated to reduce the hardness properties of the materials, or to improve the malleability of the materials, or to otherwise improve other properties of the materials to permit the methods described herein to be applied to the materials used to form the neck  210  and body  220 . 
     The rear face  221  of the body  220  of the dispense tip  200  is configured to be mounted to a material dispense pump (not shown), whereby the pump transports materials for dispensing, such as viscous fluids, to the dispense tip  200 . The body  220  is typically secured to a dispense pump by a nut, but other configurations for securing are possible. The dispense tip  200  can be used in conjunction with any number of different dispense pumps and related systems; such pumps being of the type disclosed in U.S. Pat. Nos. 6,511,301, 6,892,959, 6,983,867, and 7,331,482, the contents of each being incorporated herein by reference. 
     During a dispensing operation, material is dispensed from the material dispense pump into a proximal end, or input end  201 A, of the dispense tip  200  through the body  220  and neck  210 , where it is transferred through a neck hole or bore  230 , and output through an opening at an output end  245  of an outlet hole  240  at the distal end of the neck  210 . The opening at the output end  245  of the outlet hole  240  has a very small inner diameter D 3  that permits dot or line patterns to be accurately dispensed onto a substrate at geometries at an order of magnitude smaller than those obtainable by conventional means, for example, on the order of less than 0.001-0.003 inches in diameter or width. The type of pattern dispensed from the pump and dispense tip  200  depends on the application. For example, dots of material can be dispensed for applications that require precise discrete placement of small volumes of material, and lines of material can be dispensed for other applications, such as small-scale underfill or encapsulation. 
     The outlet hole  240  of an inner diameter D 2  is formed at a distal end, or outlet hole region  201 B, and communicates with the neck hole  230  through the neck  210 . In one embodiment, a small drill bit is used to machine an outlet hole or bore, for example, a conventional drill bit having an outer diameter ranging from at least 0.004 to 0.010 inches. Assuming this, the inner diameter D 2  of the outlet hole likewise has a range from at least 0.004 to 0.010 inches. In another embodiment, the neck hole  230  includes the outlet hole, such that the dispense tip  200  includes a taper or draft between an input end of the neck hole  230  proximal to a funnel  260  (described below) and an output end of the outlet hole, the taper or draft being formed during formation of the dispense tip, for example, by a molding process. 
     In an embodiment, the outlet hole  240  initially has an inner diameter D 2  that is generally the same at both an input end  235  of the outlet hole  240  and at an opening at the output end  245  of the outlet hole  240 . This initial configuration of the outlet hole  240  of uniform inner diameter D 2  is represented in  FIG.  2 B  by dashed lines  241 . In accordance with the embodiments of the present invention, the opening at the output end  245  of the outlet hole  240  undergoes a reduction process whereby the initial inner diameter D 2  at the opening at the output end  245  of the outlet hole  240  is reduced to a reduced inner diameter D 3 . This reduction can occur, for example, according to the embodiments described below in connection with  FIGS.  3 A- 3 C . As a result of the reduction, the outlet hole  240 , initially having a substantially cylindrical inner surface, will have a tapered inner surface  251 , the tapered inner surface  251  transitioning from the input end  235  of the outlet hole  240  having substantially the initial inner diameter D 2  to the output end  245  having the reduced inner diameter D 3 . Although the interior cross-sectional surfaces of the outlet hole  240  are referred to as having “diameters,” such cross-sections are not necessarily a perfect circle, especially following the reduction process; thus, the term “diameter,” when referring to the “initial” and “reduced” inner diameters D 2 , D 3  of the outlet hole  240  can include other, non-circular, cross-sectional shapes, in which case, the term “diameter” can also refer to “widths” of those cross-sectional shapes. 
     The resulting tapered inner surface  251  of the outlet hole  240  can be considered to have a conical shape or parabolic shape as a result of the reduction process; however, other inner surface shapes are equally applicable to the embodiments of the present invention. In one example embodiment, the inner diameter D 2  of the input end  235  of the outlet hole  240  is approximately 0.006 inches and the reduced inner diameter D 3  of the output end  245  of the outlet hole  240  is approximately 0.003 inches, and the distance between the input end  235  and the output end  245  is approximately 0.025 inches. This results in a reduction in diameter of 0.003 inches over a distance of 0.025 inches, which roughly amounts to the tapered inner surface  251  of the outlet hole  240  having an angle of about 3.5 degrees relative to the longitudinal axis  283  of the outlet hole  240 . However, other taper angles are equally applicable to embodiments of the present invention, depending on the application. The outlet hole  240  is distinguished from the dispense tip outlet hole of the example dispense tip illustrated at  FIG.  1   , which has a single, constant, diameter D 2  over the length of the outlet hole region. The tapered outlet hole  240  illustrated in  FIG.  2    is contributive to superior material flow at relatively low pressure, as compared to conventional tips, resulting in reduced clogging with enhanced volume control, due in part to the reduced inner diameter D 3  of the output end  245  of the outlet hole. In addition, pressure reduction for dispensing is also enhanced, with improved flow characteristics due to the gradual reduction of the inner diameter from the input end  235  of the outlet hole  240  to the output end  245 , which, as discussed above, can further enhance dispensing precision. 
     The neck hole  230  is formed through the body  220  and through the input end  211  of the neck  210  along a longitudinal axis of the neck  210  to the outlet hole region  201 B of the neck  210 . The neck hole  230  has an inner diameter D 1  that is greater than the diameter D 2  at the input end  235  of the outlet hole  240 . In one example, the inner diameter D 1  of the neck hole  230  is about 0.025 inches. A first inner taper  250  transitions the inner diameter D 1  of the neck hole  230  to the inner diameter D 2  at the input end  235  of the outlet hole  240 . In certain embodiments, the first inner taper  250  has a surface that is generally conical or parabolic in shape and lies at an angle of about 30 degrees relative to a longitudinal axis  283  of the neck hole  230 . However, other taper angles are equally applicable to the embodiments of the present invention, depending on the application. In a case where the neck hole  230  and first inner taper  250  are formed by drilling, the inner surface of the first inner taper  250  conforms to the outer surface of the end of the drill bit. 
     A funnel  260  can be optionally formed in the rear face  221  of the body  220  through a portion of the body  220 , and finished in the body  220  at a funnel angle, for example, on the order of 45 degrees relative to the longitudinal axis  283  of the neck hole. Other funnel angles are equally applicable to embodiments of the present invention, depending on the application. The funnel  260  includes an inlet proximal to the rear face  221 , and communicates with an outlet of a material dispense pump (not shown) at the rear face  221 . The funnel  260  further includes an outlet that communicates with the neck hole  230 . In this manner, a continuous fluid path is formed from the funnel  260  of the body  220  at an input end  201 A of the dispense tip  200  to the outlet hole opening at the outlet hole region  201 B of the dispense tip. 
     In other embodiments, as disclosed in U.S. Pat. No. 6,547,167, incorporated by reference above, the funnel  260  includes a plurality of outlets, and the dispense tip includes a like plurality of necks, each outlet communicating with a corresponding neck of the plurality of necks, wherein a single fluid path is provided between each outlet of the funnel and the output end of each neck. 
     The outlet hole region  201 B of the neck  210  has a first outer taper or bevel  270  at the outlet hole region  201 B, which, in some embodiments, can also correspond with a region of the first inner taper  250 . In one embodiment, the neck  210  can be configured to have a first outer diameter OD 1  along a majority of the length of the neck  210  that is reduced to a second outer diameter OD 2  in a region of the outlet hole  240  by the first outer taper  270 . In one embodiment, the first outer taper  270  comprises a bevel that is formed by grinding the neck  210  along the longitudinal axis of the neck using a grinding wheel, for example, in accordance with formation techniques disclosed in U.S. Pat. No. 6,896,202, the contents of which are incorporated herein by reference in their entirety. In this manner, the bevel includes longitudinal scars that are parallel to the longitudinal axis of the dispense tip neck  210 . 
     As a result of the reduction process of the inner diameter D 3  of the outlet hole  240 , according to the embodiments disclosed herein, the neck  210  can further include a second outer taper or bevel  271  at the distal end of the neck  210  that transitions the outer surface having the second outer diameter OD 2 , for example, in the region of the body of the outlet hole  240 , to an outer surface having a third outer diameter OD 3  that is in a region of the neck proximal to the opening at the output end  245 . The second outer taper  271  results in the output end  245  of the outlet hole  240  having an even further reduced surface tension, leading to a higher degree of dispensing precision capability. In another embodiment, the second outer taper  271  includes longitudinal scars that are parallel to the longitudinal axis of the dispense tip neck  210 . The longitudinal scars can be formed by grinding the neck  210  along the longitudinal axis of the neck  210  prior to forming the second outer taper  271 . 
       FIGS.  3 A- 3 C  are cross-sectional views illustrating sequential steps of forming an outlet hole in the dispense tip of  FIGS.  2 A- 2 B , in accordance with embodiments of the present invention. In one embodiment, as illustrated at  FIGS.  3 A- 3 C , a male punch  310  and female die  320  are used to form a reduced-diameter outlet hole  240 . 
     As shown in  FIG.  3 A , the outlet hole region  201 B of the neck  210  is inserted into a female indentation or impression  325  formed in the female die  320 . The inner surface of the female impression  325  can be polished, to avoid formation of tool scars on the outer taper  271  during the reduction process. The neck  210  is preferably positioned along a vertical axis relative to the female die  320 , but can also be positioned at an acute angle relative to the vertical axis. 
     In one embodiment, the die  320  is composed of a material, for example, carbide or other tool steel, having hardness properties that are greater than the material used for forming the dispense tip neck  210 . 
     The female impression  325 , in one embodiment, is in the shape of a cone, wherein the wall of the female impression  325  is tapered inwardly toward a point at the bottom of the impression  325 . In other embodiments, the female impression  325  can be of any concave shape, such as a parabolic shape, that would result in reduction of the inner diameter D 3  of the opening at the output end  245  of the outlet hole  240 . In one embodiment, the diameter of a top portion of the impression  325  at the surface of the die  320  is about 0.040 inches, and the depth of the female impression  325  is about 0.020-0.040 inches. However, the female impression  325  can have dimensions that vary from those described herein so long as a dispense tip can be received by the female impression  325 , and so long as the tip can be formed or modified by interaction with the female impression  325  to have at least one of an second inner taper  251 , an opening at the output end  245  having an inner diameter D 3  smaller than an inner diameter D 2  at an input end  235  of the outlet hole, and a second outer taper  271 . 
     As shown in  FIG.  3 B , an elongated male punch  310  is inserted into the neck hole  230  through the body  220  and the neck  210  until it abuts the input end of the hole  235  and the first inner taper  250 . The dispense tip  200  and inserted punch  310  are placed in position on a machine, such as a bridge port drill press, between the machine and the die  320 , and the machine is incrementally made to bear down on the punch  310 , which, in turn, bears down on the first inner taper  250  of the dispense tip  200 . At this time, prior to application of further pressure on the dispense tip, to initiate the reduction process, the dispense tip, when induced by an operator, may turn freely about the punch  310 . As the distance between the machine and die  320  is incrementally reduced, at a certain point, the dispense tip  200  will no longer turn freely about the punch  310 . This point can be used as a gauge to determine where to initiate the reduction process. During the reduction process, the dispense tip  200  is in a substantially static position, as its inner taper  250  is under continuous pressure from the punch  310 . 
     In one embodiment, the punch  310 , like the dispense tip  200 , is positioned in a substantially vertical position relative to the female die  320 . In another embodiment, the punch  310  and the dispense tip  200  are positioned in a different position, such as a substantially horizontal position. The punch  310  has an outer diameter that is slightly less than the inner diameter D 1  of the neck hole  230 , for example, 0.025 inches. The punch  310 , like the die  320 , can be formed of a material having a hardness that is greater than the material used to form the dispense tip  200 , for example, carbide or other tool steel. The punch  310  can include a tapered distal end  311  that closely coincides with the first inner taper  250  of the neck  210 . For example, the outer surface of the tapered distal end of the punch  310  lies at an angle relative to the longitudinal axis of the punch  310  that is similar to the angle of the first inner taper  250  of the neck  250 , for example, 30 degrees relative to the longitudinal axis of the neck  210 . 
     In one embodiment, a controlled external force F is applied to the punch  310  oriented in a direction toward the die  320 . In other embodiments, an external force is applied to the base  220  or neck  210  of the tip  200 . As shown in  FIG.  3 B , the external force is preferably a controlled downward vertical force F that is applied by the punch  310  to the dispense tip  200  at the first inner taper  250 . 
     The source of the controlled external force F can be a machine known to those of ordinary skill in the art, for example, a milling machine or a bridge port drill press. In another embodiment, the machine can apply a force F that is sufficient to move the male punch  310  toward the female die  320  in increments, for example, a machine capable of providing a force to the neck  210 , by incrementally moving the punch  310  in a direction toward the die  320  in 0.001 inch increments. After each incremental change in position, the male punch  310  can be removed from the neck  310  and measurements can be taken of the reduced outlet hole, for example, the inner diameter D 2  of the input end  235 , the reduced inner diameter D 3  of the output end  245 , the distance between the input end  235  and the output end  245 , and the tapered inner surface  251  angle relative to the longitudinal axis  283  of the outlet hole  240 . 
     The exertion of force applied against the first inner taper  250  of the dispense tip results in the compression of the outlet hole region  201 B of the neck  210  by the surface of the impression  325  of the die  320 , which incrementally decreases in inner diameter along its length. The presence of the outer bevel  270  at the output end  201 B of the neck  210  enhances the compression process, since the bevel  270  reduces the wall thickness of the neck  210  in this region. In addition, the punch  310  is configured to avoid substantial penetration into the outlet hole  240  during the reduction procedure so that it does not interfere with inward compression of the inner walls of the outlet hole  240  during the procedure. The amount of vertical force F being applied can be determined manually, or the amount of force F can be controlled by using a computer in communication with a machine, such as a pneumatic machine. As a result, as shown in  FIG.  3 C , the outside surface of the outlet hole region  201 B of the neck  210  substantially conforms to the polished tapered walls of the impression  325 . As a result of the external force being applied to the first inner taper  250 , as shown in  FIG.  3 C , the outlet hole region  201 B of the neck  210  is pressed against the polished surface of the impression  325 , which causes the outlet hole  231  to change shape as it undergoes deformation. Specifically, the shape of the impression  325  and the force of the punch  310  being applied to the first inner taper  250  cause the outlet hole  240  to have an output end  245  of a reduced inner diameter D 3  as the outlet hole region  201 B becomes further pressed into the die  320 . As described above, in one embodiment, this results in the outlet hole  240  having an input end  235  of substantially the second inner diameter D 2  of the original outlet hole, and has an output end  245  of the reduced, formed third inner diameter D 3 . The tapered inner surface  251  of the outlet hole  240  is formed between the input end  235  and the output end  245  as a result of the inner walls  232  at a portion of the outlet hole  240  being compressed inwardly. Other regions of the dispense tip  200 , for example, the neck hole  230 , do not experience any change in shape as a result of the outlet hole reduction. 
     As a result of forming the reduced-diameter outlet hole  240 , the output end  245  of the outlet hole  240  can have a sharpened point. In one embodiment, the sharpened point can be removed by grinding or machining the sharpened point, thereby forming a small flat surface at the output end  245 , while retaining an outlet hole  240  having a reduced inner diameter D 3  and a wall thickness at the end of about 0.001 inches. Removing the sharpened point in this manner protects the dispense tip from damage, and ensures the accuracy and reliability of the dispense tip, during dispensing operations. 
     In one embodiment, the neck  210  remains stationary while the external force is applied to the neck  210  by the punch  310 . In another embodiment, the neck  210  can be rotated about a vertical axis while the external force is applied to the punch  310 . During rotation, the punch  310  can be forced downward along the vertical axis toward the female impression  325 . 
     A dispense tip outlet hole  240  can therefore be formed having an opening that has a smaller inner diameter than dispense tips machined according to conventional procedures, for example, on the order of less than 0.004 inches, which is less than the diameter achievable by conventional formation. This corresponds to a resulting dot diameter or line width of less than 0.006 inches, which is less than dot diameters or line widths currently achievable. 
     As a result of the outlet hole reduction, when the outlet hole region  201 B of the neck  210  is pressed into the surface of the die impression  325 , a second outer taper  271  can be formed at the outlet hole region  201 B of the neck  210  having a greater angle relative to the longitudinal axis  283  of the outlet hole  240  than the first outer taper  270 . 
     In one embodiment, prior to forming the second outer taper  271 , the neck  210  can be beveled, for example, in accordance to the method illustrated at U.S. Pat. No. 6,896,202, incorporated by reference above. After the bevel is formed, the beveled neck can be polished using a polishing compound, for example, Jeweler&#39;s rouge. In another embodiment, after the outlet hole  240  reduction process is performed, the outlet hole region  201 B can be polished using a polishing compound, for example, Jeweler&#39;s rouge. 
     The fabrication methods illustrated in  FIGS.  3 A- 3 C  can be applied to a machined dispense tip, for example, the dispense tip illustrated at U.S. Pat. No. 6,547,167, incorporated by reference above, or a molded dispense tip, for example, a ceramic dispense tip. Although the above examples describe initial formation of the outlet hole  240  using drill bits or machining tools of the smallest outer diameters available, for example, on the order of 0.004 inches, in other embodiments, the outlet hole  240  can be initially formed to much larger inner diameters, for example, on the order of 0.010 inches, or greater, for example, using larger-diameter drill bits. The resulting outlet hole  240  can then be reduced in inner diameter at its output end according to the aforementioned process. For example, the resulting 0.010 inch inner diameter outlet hole  240  can be reduced to 0.006 inches in inner diameter at its output end  245 . The resulting dispense tip having an outlet hole  240  that tapers in inner diameter from 0.010 inches at its input end  235  to 0.006 inches at its output end  235  would offer improved material flow characteristics, reduced pressure, and reduced propensity for clogging, as compared to a similar dispense tip having an outlet hole formed using a 0.006 inch outer-diameter drill bit, since such a similarly formed dispense tip would have a constant inner diameter of 0.006 inches along its length, including at its input end  235 . In addition, the aforementioned fabrication methods can equally be applied to other types of dispense tips, for example, dispense tips formed according to other means, such as molded dispense tips. 
       FIG.  4 A  is an illustrative cross-sectional view of a dispense tip  300  in accordance with another embodiment of the present invention.  FIG.  4 B  is an enlarged partial cross-sectional view of the dispense tip neck  300  of  FIG.  4 A . As shown in  FIGS.  4 A- 4 B , a reduced-diameter outlet hole  285  is formed at an output end portion of an outlet hole  241  at the outlet hole region  201 C of the neck  210 . The initial configuration of the outlet hole  285  prior to reduction is represented in  FIG.  4 B  by dashed lines  281 . In contrast to the embodiment shown in  FIGS.  2 A- 2 B , the input end  235  of the outlet hole  241  shown in the embodiment of  FIGS.  4 A- 4 B  has an inner diameter D 2′  that uniformly extends through a substantial portion of the output end of the neck  210  to the outlet hole  285 . A tapered inner surface  253  transitions from the end of the elongated input end  235  having the inner diameter D 2′  to the output end of the outlet hole  285  having a substantially reduced inner diameter D 3′ . In addition, an outer taper  273  at the distal end of the neck  210  transitions an outer surface having a second outer diameter OD 2′ , for example, in the region of the body of the outlet hole  285 , to an outer surface having a third outer diameter OD 3′  that is in a region of the neck proximal to an opening at the output end of the outlet hole  285 . 
       FIG.  5    is an illustrative cross-sectional view showing an outlet hole  285  of the dispense tip of  FIGS.  4 A- 4 B  being formed in accordance with an embodiment of the present invention. A dispense tip is formed in a similar manner as described at  FIGS.  3 A- 3 C . However, the shape of the impression  425  and/or the force of the punch  410  being applied to the first inner taper  250  in  FIG.  5    is different than the shape of the impression  325  and/or the force of the punch  310  that is applied in the embodiment shown in  FIGS.  3 A- 3 C . Specifically, the geometry of the outlet hole  285  shown in  FIG.  5    is influenced by factors such as the amount of force applied by the punch  410  against the dispense tip or the angle α′ of the wall of the impression  425 , resulting in the outlet hole  285  in  FIG.  5    assuming a different configuration than that of the outlet hole  240  shown in  FIG.  3 C . 
       FIGS.  6 A- 6 B  are illustrative cross-sectional views of a dispense tip  500  formed by a combination of a separately machined neck  510  being joined to a body  510  in accordance with an embodiment of the present invention. The neck  510  includes the advantageous configuration of a dispense tip having a reduced-diameter outlet in accordance with the embodiments described above. A hole  508  is formed in the body  520 , and the neck  510  is press-fit, bonded, or welded into position in the hole  508 . 
       FIG.  7    is an illustrative cross-sectional view of a dispense tip  600  having a LUER™-style body  620  in accordance with an embodiment of the present invention. The dispense tip  400  has a LUER™-style body comprising a male LUER™ fitting or coupling  690  at an inlet of the body  620  which is coupled to a female LUER™ fitting (not shown) of a dispense pump. The LUER™-style coupling  690  is formed to comply with the standards of LUER™-style fittings. In an embodiment, The LUER™-style coupling  690  can be machined from a common stock or molded from materials such as plastics or ceramics. In one embodiment, as illustrated at  FIG.  7   , the outlet region of the dispense tip of  FIG.  7    is similar to the outlet region illustrated at  FIG.  2 B . In another embodiment, the outlet region of the dispense tip of  FIG.  7    is similar to the outlet region illustrated at  FIG.  4 B . 
     As shown in  FIG.  7   , the body  620  is machined from a stock that is common with, and unitary with, the neck  610 . Such unitary construction provides a dispense tip that is of enhanced strength and rigidity, and therefore leads to more accurate and consistent dispensing. In other embodiments, the body  620  and neck  610  are machined, molded, or otherwise formed, as two independent components, similar to the dispense tip illustrated in  FIG.  6   . The body  620  is formed to further include a recess (not shown) that is adapted to receive the inlet end of the neck  210  as shown. The neck  610  may be bonded to the body  620 , for example, by press-fitting, bonding, or welding. In this manner, an inlet region  660  of the body  220  is funneled to an input port of the neck  610 . 
     The above embodiment illustrated at  FIG.  7    therefore offers the advantage of compatibility with a LUER™-style pump fitting, while improving system accuracy and strength over the traditional dispense tip configurations. 
     As described above, embodiments of the present invention are directed to dispense tips having reduced-diameter outlet holes and methods of manufacturing the same, which permits precise patterns, such as dot and line patterns, with improved accuracy, having very small diameters, to be dispensed. In particular, the dispense tip offers an outlet hole having a smaller diameter than the initial diameter of the hole formed through the dispense tip, the outlet hole diameter resulting in dot or line patterns to be dispensed having a smaller diameter than currently achieved by conventional dispense tips. The reduced-diameter outlet hole is formed by inserting the output end of the dispense tip into a female die impression or cavity, and applying a controlled external force to the input end of the dispense tip or to a male punch that is inserted into a hole that is formed through the neck of the dispense tip. In controlling the amount of external force being applied, the walls of the output end of the dispense tip conform to the geometry of the female die impression to form the outlet hole region. By applying a controlled external force in this manner combined with the geometry of the die impression, this technique results in an opening at the output end of the outlet hole having a very small diameter, thereby capable of achieving a high level of dispensing accuracy. 
     While embodiments of the invention have been particularly shown and described above, it will be understood by those skilled in the art that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.