Patent Application
20190039085
The present disclosure generally relates to a nozzle assembly. More particularly, the present disclosure describes various embodiments of a nozzle assembly, as well as a dispensing apparatus using the nozzle assembly.
Nozzles are widely used in different industries when a dispensing process is required to dispense or deposit an amount of liquid from a container onto a surface. There is a variety of nozzles available for different dispensing applications and industries.
In the semiconductor industry, various dispensing processes are used to dispense liquid adhesives onto a lead frame for semiconductor device or die attachment. A liquid adhesive such as a particle-filled epoxy resin is commonly used. The rapid growth of the semiconductor industry has reduced the dimensions of semiconductor dies to micrometer and nanometer dimensions. The dispensing processes have become more demanding to achieve precise die attachment at such accuracies. A nozzle with a small internal diameter is often used in the dispensing processes to dispense small amounts of the particle-filled epoxy resin with excellent volume consistency and precision. However, the particles in the epoxy resin may cause blockages to occur at the nozzle. Moreover, with the continued reduction in semiconductor die sizes, the nozzle diameter will decrease and the ratio of the particle sizes to the nozzle diameter will increase, thereby increasing the likelihood of the particles causing blockages at the nozzle.
The occurrence of such blockages may be attributed to the internal geometry of the nozzle. Two possible modes of nozzle blockage have been identified. The first mode is the formation of a clogging bridge or arch. The clogging bridge usually forms near an intermediate inlet of the nozzle from one section to another. The second mode is the formation of air bubbles within the nozzle. The trapped air bubbles are likely to cause an airlock which blocks the dispensing pathway.
The formation of clogging bridges has been known to occur particularly in nozzles with a tapered bore. A clogging bridge is formed from particles in the liquid and is self-supported due to the normal and frictional forces developed from interactions between the particles belonging to or forming the clogging bridge itself. When the resultant force due to the normal and frictional forces is greater than the resultant force of the weight of the liquid and any external forces or loads applied on the particles, the clogging bridge develops and gradually becomes stabilized. The probability of clogging bridge formation is particularly related to the apex angle of the tapered bore. The structural strength and sturdiness of the clogging bridge are also related to the apex angle.
Nozzles may also be blocked by trapped air in the liquid. In the nozzle 10 of
The dispensing performance of nozzles can worsen significantly due to the occurrence of nozzle blockage, particularly when a time-pressure dispenser is used with the nozzles. Control of the time and pressure parameters of such time-pressure dispensers may seek to improve the consistency of liquid dispensation. However, even if the parameters are well controlled, the dispensed liquid can still be inconsistent when the nozzle condition changes. Such time-pressure dispensers cannot ensure consistency of the liquid flow rate, when the nozzle has been affected by blockage. The aforementioned modes of nozzle blockage change the nozzle condition, and are likely to adversely affect effective control of the liquid flow.
Therefore, in order to address or alleviate at least one of the aforementioned problems and/or disadvantages, there is a need to provide a nozzle assembly in which at least one improvement and/or advantage over the aforementioned prior art is achieved.
According to a first aspect of the present disclosure, there is provided a nozzle assembly comprising: a nozzle body having a nozzle bore extending between a proximal portion and a distal portion of the nozzle body; and a tube having a lumen extending between a proximal end and a distal end of the tube, wherein the tube is joined to the nozzle body through the nozzle bore, such that the proximal end of the tube extends beyond the proximal portion of the nozzle body and the distal end of the tube extends beyond the distal portion of the nozzle body.
According to a second aspect of the present disclosure, there is a dispensing apparatus comprising a dispensing device and a nozzle assembly. The dispensing device comprises: a barrel portion for containing a liquid; and an outlet fluidly communicable with the barrel portion for dispensing the liquid. The nozzle assembly is coupled to the dispensing device via the outlet. The nozzle assembly comprises: a nozzle body having a nozzle bore; and a tube having a lumen extending between a proximal end and a distal end of the tube, the tube being joined to the nozzle body through the nozzle bore, wherein the proximal end of the tube extends beyond the nozzle body and through the outlet such that the proximal end of the tube is submersible in the liquid; and wherein the distal end extends beyond the nozzle body such that the liquid is configured to flow through the lumen and to be dispensable via the distal end.
An advantage of the present disclosure is that the nozzle assembly significantly mitigates the risks of a clogging bridge and/or an airlock forming along the dispensing pathway, thereby reducing the likelihood of nozzle blockages that prevent or impede liquid flow. Use of the nozzle assembly improves and stabilizes dispensing performance.
A nozzle assembly according to the present disclosure is thus disclosed herein. Various features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments of the present disclosure, by way of non-limiting examples only, along with the accompanying drawings in accordance with embodiments of the present disclosure.
For purposes of brevity and clarity, descriptions of embodiments of the present disclosure are directed to a nozzle assembly in accordance with the drawings. While aspects of the present disclosure will be described in conjunction with the embodiments provided herein, it will be understood that they are not intended to limit the present disclosure to these embodiments.
In various embodiments of the present disclosure, there is a nozzle assembly 100 as shown in
The tube 140 may be joined to the nozzle body 120 by inserting the tube 140 through the bore 126 and fixing the tube 140 to the nozzle body 120 permanently with an adhesive material. In one embodiment as shown in
In some embodiments as shown in
In the nozzle assembly 100, the tube holder body 160 supports the tube 140 and aligns the position of the tube 140 within the nozzle body 120. Particularly, the tube holder body 160 aligns the tube 140 with respect to the nozzle body 120, such that the lumen 146 is concentric with respect to the bore 126 and the lumen 146 is perpendicular to a proximal surface 128 of the nozzle body 120.
The tube holder body 160 may be made of or coated with a material to attenuate forces and hoop stresses exerted on the tube 140, thereby mitigating the risk of structural damage to the tube 140. An example of this material is Teflon®, which has a Young's modulus that is comparatively much lower than that of the tube and this facilitates the insertion of the tube holder body 160 into the nozzle body 120 through the bore 126, and the insertion of the tube 140 into the tube holder body 160 through the bore 162. Other components of the nozzle assembly 100, including the nozzle body 120 and tube 140, may also be made of Teflon® or other materials known to the skilled person.
In various embodiments of the present disclosure, there is a dispensing apparatus 200 as shown in
With further reference to
The nozzle assembly 100 is thus coupleable to the dispensing device 220 via the outlet 224. Upon coupling as shown in
In one embodiment, the proximal portion 122 engages with the outlet 224 through an interference fit. The proximal portion 122 has a slightly larger external dimension or outer diameter than an internal dimension or inner diameter of the outlet 224 to achieve the interference fit. The interference fit forms the peripheral seal between a peripheral mating surface 130 of the nozzle body 120 and a peripheral mating surface 230 of the outlet 224. Alternatively or additionally, the proximal portion 122 is narrower than the distal portion 124, such that a planar mating surface 132 is formed at the interface between the proximal portion 122 and the distal portion 124. The planar mating surface 132 is contactable against a planar mating surface 232 of the outlet 224. The engagement of the proximal portion 122 with the outlet 224 forms the planar seal between the planar mating surfaces 132 and 232.
The nozzle holder body 180 secures the coupling/engagement between the proximal portion 122 of the nozzle assembly 100 and the outlet 224 of the dispensing device 220 as a result of the locking engagement between the locking mechanisms 182 and 228. To facilitate the engagement of the proximal portion 122 to the outlet 224, the proximal portion 122 includes a chamfer or fillet 134 to guide the proximal portion 122 into the outlet 224. Actuation of the nozzle holder body 180 moves the proximal portion 122 towards the outlet 224 for engagement. The proximal portion 122 can be further forced into the outlet 224 by tightening the nozzle holder body 180, thereby tightening the locking engagement. The tightening of the nozzle holder body 180 results in the planar mating surface 132 exerting more pressure on the planar mating surface 232, thereby strengthening the planar seal.
In one embodiment of the dispensing apparatus 200 as shown in
In another embodiment, the nozzle assembly 100 may be coupled to the dispensing device 220 before the dispensing device 220 is filled with a liquid for subsequent dispensation. Upon coupling, the proximal end 142 of the tube 140 extends into the outlet 224 such that the proximal end 142 is submersible in the liquid. In other words, when the dispensing device 220 is filled with the liquid, the proximal end 142 will be submerged in the liquid.
As shown in
The lumen 146 of the tube 140 forms part of the dispensing pathway for dispensation of the liquid, such as a particle-filled epoxy resin, contained in the dispensing device 220. The lumen 146 has a uniform cross-section such that the fluid pressure and volume fraction of the particle-filled epoxy resin remain substantially constant along the dispensing pathway. The uniform cross-section of the lumen 146 thus impedes formation of a clogging bridge or arch along the dispensing pathway. Moreover, the extension of the proximal end 142 into the liquid reduces the area where the clogging bridge may form, thereby weakening the structural integrity on which a clogging bridge may be founded.
Therefore, the nozzle assembly 100 addresses at least the aforementioned two modes of nozzle blockages that can occur separately or concurrently in a dispensing device 220. The nozzle assembly 100 significantly mitigates the risks of a clogging bridge and/or an airlock forming along the dispensing pathway, thereby reducing the chance of nozzle blockages that prevent or impede liquid flow, especially for particle-filled liquids such as a particle-filled epoxy resin. The liquid dispensation is more stable and consistent, and the flow rate of the dispensed liquid is substantially constant. Use of the nozzle assembly 100 in a dispensing apparatus 200 or together with a dispensing device 220 thus improves and stabilizes dispensing performance.
In the foregoing detailed description, the preferred embodiment of the present disclosure in relation to a nozzle assembly is described with reference to the provided figures. The description of the various embodiments herein is not intended to be limited only to specific or particular representations of the present disclosure, but merely to illustrate non-limiting examples of the present disclosure. The present disclosure serves to address at least one of the mentioned problems and issues associated with the prior art. Although only the preferred embodiment of the present disclosure is disclosed herein, it will be apparent to a person having ordinary skill in the art in view of this disclosure that a variety of changes and/or modifications can be made to the disclosed embodiments without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure as well as the scope of the following claims is not limited to embodiments described herein.
