WO2012083561A1

WO2012083561A1 - Nozzle for electronic assembly

Info

Publication number: WO2012083561A1
Application number: PCT/CN2010/080266
Authority: WO
Inventors: Peter PERSCHEWSKI; Manfred Kirchberger; Heinrich Zeininger; Florian Eder; Anett BERNT
Original assignee: Siemens AG; Siemens Corp
Current assignee: Siemens AG; Siemens Corp
Priority date: 2010-12-24
Filing date: 2010-12-24
Publication date: 2012-06-28
Anticipated expiration: 2013-06-24

Abstract

A nozzle for electronic assembly with an anti-adhesive coating and a preparation method thereof are provided. With the nozzle coated with an anti-adhesive coating, it will be more difficult for dust, dirt and particles to stick on the surface of the nozzle, and thus less vacuum errors and improved process stability in the production line can be obtained.

Description

Nozzle for Electronic Assembly

Field of the Invention

The present invention relates to a nozzle for electronic assembly and a preparation method thereof. More particularly, the present invention relates to a nozzle for electronic assembly with an anti-adhesive coating and a preparation method thereof.

Background of the Invention

Pick-up tools for electronic assembly, so called nozzles, are used for picking and placing electronic devices for electronic assembly. Vacuum is used for fixing the electronic components at the tip of the nozzle during the picking up. A channel in the nozzle provides vacuum or air kiss to pick and place the components.

Due to the miniaturization of electronic components, smaller nozzles with smaller vacuum channels are necessary. These channels are often contaminated or jammed by particles from the manufacturing environment. This leads to a decrease in component placement stability and an increase of non working electronic products.

In order to guarantee a fully operable placement machine, a frequent check of the functionality of the nozzle is performed. In most cases a cleaning procedure is necessary, which is done separately, outside of the machine. Besides the extra cost for cleaning, such as personnel and cleaning agents, the main disadvantage of this maintenance is an interruption of the production process, which results in decreased productivity and increased costs for production per item.

Another problem is the counterfeiting of original pick-and-place nozzles. Brand protection is difficult, as the nozzles are small in size and do not offer enough area to place common anti-counterfeiting symbols like holograms or watermarks. Therefore, a nozzle that will not be easily jammed is needed for the electronic assembly process. Furthermore, it will be advantageous if the nozzle can be distinguished easily for the convenience of anti-counterfeiting.

Summary of the Invention

To overcome the defects caused by the contaminated nozzle, a nozzle for electronic assembly is provided in one aspect of the invention. The nozzle comprises an anti-adhesive coating by which the problems with particle contamination can be overcome or be minimized. It will be more difficult for dust, dirt and particles to stick on the nozzle's surface, thus less vacuum errors and improved process stability in the production line can be achieved.

The nozzle can be fully coated, or partly coated at least on one or more areas which are sensitive to contamination. For example, the nozzle can be partly coated only on the surface of its channel, or the nozzle can be partly coated only on the surface of its tip.

Preferably, the coating has a relatively low thickness so that the geometrical dimensions of the nozzle will not be changed. The thickness can be ΙΟηηι-ΙΟμηι and/or no more than 5% of the diameter of the channel of the nozzle, depending on the type of nozzle being used. For example, for a Vectra A230 706/906 type of nozzle, whose channel has a diameter of 200μπι, the thickness of the coating can be in the range of lOnm to ΙΟμπι. With such thickness of the coating, the geometrical dimensions and the suction force of the nozzle will not be affected significantly.

In one embodiment of the invention, the coating comprises an organo-polymeric film with hydrophobic properties. In general, all soluble polymers can be used to prepare the organo-polymeric film with hydrophobic properties. The organo-polymeric film can comprise at least one functional group of alkyl, cycloalkyl, aryl or partially fluorinated alkyl chains. In particularly, the at least one functional group is selected from the group consisting of alkyl-groups with C1 -C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; and partially fluorinated alkyl groups with C3-C20.

In another embodiment of the invention, the coating is prepared by a sol-gel process. In the sol-gel process, metal-precursor material is hydrolyzed and subsequently goes through a condensation step. The metal precursor material, in particular, can be metal halogenide such as CH₃-Si-Cl₃ (Tri-chloro-methyl-silane) or metal-alkoxide. The metal can be silicon, aluminum, titanium or zirconium. The hydrophobic properties of the coating are due to the at least one functional group, which can either be linked to the metal-precursor material or can be added during the hydrolysis-condensation process. Preferably the at least one functional group is selected from the group consisting of alkyl-groups with C1-C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; and partially fluorinated alkyl groups with C3-C20. The hydrophobic properties of the coating prevent water and other polar substances from adhering to the surface of the nozzle.

In a further embodiment of the invention, the coating is smooth enough to decrease the amount of particles adhered to the surface of the nozzle. Preferably, the average roughness of the surface is less than Ι μπι, more preferably less than lOOnm.

In a further embodiment of the invention, the coating is also anti-static. The anti-static property can be obtained by adding electrically conductive particles or fibers to the coating liquid. These particles or fibers can be made of carbon, metals or conductive metal oxides. These particles or fibers can be in nano-scale. The amount of the particles or fibers used in the coating can be in the range of 0.5 to 30 wt. %, based on the total weight/surface area of the coating. A preferable electrical resistivity of the coating is less than l x l O¹⁰ Ohm/square. Partial charges are a major factor allowing particles from the manufacturing environment to stick on the surface of the nozzle. By the anti-static property, the density of partial charges on the nozzle surface is decreased. In addition to the hydrophobic properties, the anti-static property further facilitates the decrease of particles from the manufacturing environment on the surface of the nozzle. As a result, dry cleaning with air will be sufficient for the nozzle according to the invention.

In a further embodiment of the invention, the coating comprises inorganic nano-particles for increasing mechanical stability, especially the abrasion resistance of the coating. The inorganic nano-particles can be various metal oxides.

In a further embodiment of the invention, color can be incorporated in the coating by using conventional organic dye-systems, pigments or metal-organic particles. The color of the coating can either be in the visible range or UV-range. Also fluorescent coatings or pearlescent colors can be used. With the color incorporated into the coating, the coated nozzle can be checked by the customer to distinguish the inventive nozzle from a faked one. Therefore, the coating can also be used as a very effective anti-piracy measure.

The fluorescent coating can also be used for process and quality control during the operation of picking and placing. The nozzle can pass a CCD camera and any changes at the tip of the nozzle, like the adhesion of dirt particles or the partial abrasion of the functional surface, can be online recorded. The intensity of the emitted fluorescent light is also an indicator for the thickness of the coating and therefore can also be used as a control method for the homogeneity and uniformity of the coating after application.

In an embodiment of the invention, the coating has a water contact angle in the range of 60-120°, more preferably higher than 90°.

In another aspect of the invention, a method for preparing the above-mentioned coated nozzle is provided. In general, all wet chemical coating procedures can be used, such as spraying or dipping. It should be understood that the nozzle should not be jammed by the coating materials. Accordingly, for most coating procedures, the coating liquid has to be removed from the nozzle, e.g. by blowing with compressed air, leaving only a thin coating film on the surface of the nozzle. This coating film should have a thickness of lOnm-ΙΟμπι and/or no more than 5% of the diameter of the channel of the nozzle, depending on the type of nozzle being used, so that the picking and placing performance of the nozzle will not be influenced.

In one embodiment of the invention, the method includes a sol-gel process. Preferably, in the sol-gel process, metal-precursor material, particularly metal halogenide or metal-alkoxide, is hydrolyzed and subsequently goes through a condensation step. Preferably the metal-alkoxide is used. The metal-atom can be Silicon, Aluminum, Titanium or Zirconium. Hydrophobic properties of the coating are due to at least one functional group, which can either be linked to the metal-precursor material or can be added during the hydrolysis-condensation process. Preferably the at least one functional group is selected from the group consisting of alkyl-groups with C1 -C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; partially fluorinated alkyl groups with C3-C20.

In a preferable embodiment of the invention, a novel process can be used to achieve a more reliable coating result. The uncoated nozzle is placed on a special nozzle holder, allowing air to be blown or drawn through the channel of the nozzle. The nozzle is put into the coating liquid and, similar to a syringe, the coating liquid is drawn into the channel. After a few seconds, the liquid is slowly blown out of the channel leaving a thin film on the surface of the channel, while the nozzle is slowly removed from the coating liquid leaving a thin film on the outer surface of the nozzle.

Brief Description of the Drawings

A more complete appreciation of the invention and the advantages thereof will be readily apparent and becomes better understood by reference to the following detailed embodiments when considered in conjunction with the accompanying drawings, wherein:

Figure 1 is a graph showing the comparison of the vacuum error between a standard nozzle and the coated nozzle according to Experimental Example 1.

Figure 2 is a graph showing the comparison of the vacuum offset between a standard nozzle and the coated nozzle according to Experimental Example 1.

Figure 3 is a graph showing the comparison of the vacuum error between a standard nozzle and the coated nozzle according to Experimental Example 2.

Figure 4 is a graph showing the comparison of the vacuum offset between a standard nozzle and the coated nozzle according to Experimental Example 2.

Detailed Description of the Embodiments

The embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings. It should be understood that the present invention is not limited by these embodiments described herein.

According to one embodiment of the invention, the coating is prepared by a sol-gel process. In the process, metal-precursor material is hydrolyzed and subsequently goes through a condensation step. The metal-precursor material can be metal halogenide or metal-alkoxide. Non-limited examples of the metal-alkoxide include siloxane, Tetra-ethyl-ortho-silicate. Preferably metal-alkoxide is used, wherein the metal-atom is Silicon, Aluminum, Titanium or Zirconium. The hydrophobic properties of the coating are due to at least one functional group, which can either be linked to the metal-precursor material or can be added during the hydrolysis-condensation process. Preferably the at least one functional group can be selected from the group consisting of alkyl-groups with C1-C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; partially fluorinated alkyl groups with C3-C20.

Furthermore, electrically conductive particles or fibers can be added into the coating liquid so as to improve the anti-static property of the coating. The amount of the particles or fibers used in the coating can be in the range of 0.5 to 30 wt. %, based on the total weight/surface area of the coating. These particles or fibers can be made of carbon, metals or conductive metal oxides. These particles or fibers can be in nano-scale. Non-limited examples of the particles and fibers used in the coating include carbon nano-tubes, graphenes or metal fibers.

According to another embodiment of the invention, the coating comprises an organo-polymeric film with hydrophobic properties. The organo-polymeric film can comprise at least one functional group of alkyl, cycloalkyl, aryl or partially fluorinated alkyl chains. In particularly, the at least functional group is selected from the group consisting of alkyl-groups with C1 -C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; and partially fluorinated alkyl groups with C3-C20. Non-limited examples of the polymer include a partially fluorinated silicon-oxide-epoxy-hybrid polymer and various poly-olefines.

Optionally, inorganic nano-particles can be added to the coating for increasing the mechanical stability, especially the abrasion resistance of the coating. The inorganic nano-particles can be various metal oxides, such as alumina, zirconia and silica.

According to a further embodiment of the invention, color can be incorporated in the coating to distinguish the inventive nozzle from a faked one. The color can be obtained by using conventional organic dye-systems, pigments or metal-organic particles. The color of the coating can either be in the visible range or UV-range. Also fluorescent coatings or pearlescent colors can be used.

The fluorescent coating can also be used for the process and quality control during the operation of picking and placing. In particular, the nozzles can pass a CCD camera and any changes at the tip of the nozzle like the adhesion of dirt particles or the partial abrasion of the functional surface can be online recorded.

In addition, the nozzle according to the invention can also be identified by measurement of the contact angle or surface roughness. In an embodiment of the invention, the coating of the nozzle has a water contact angle in the range of 60-120°, more preferably higher than 90°. The surface roughness can be in the range of lnm - Ι μπι.

In general, all wet chemical coating procedures can be used to prepare the coating of the invention, such as spraying or dipping. It should be understood that the channel of the nozzle should not be jammed by the coating materials. Accordingly, for most coating procedures, the coating liquid has to be removed from the channel, for example, by blowing with compressed air, leaving only a thin coating film on the surface of the nozzle. The thickness of the coating should be lOnm-ΙΟμπι and/or no more than 5% of the diameter of the channel of the nozzle, depending on the type of nozzle being used, so that the pick and place performance of the nozzle will not be influenced.

According to a preferred embodiment of the invention, a novel process can be used to achieve a more reliable coating result. The uncoated nozzle is placed on a special nozzle holder, allowing air to be blown or drawn through the channel of the nozzle. The nozzle is put into the coating liquid and, similar to a syringe, the coating liquid is drawn into the channel. After a few seconds, the liquid is slowly blown out of the channel leaving a thin film on the surface of the channel, while the nozzle is slowly removed from the coating liquid leaving a thin film on the outer surface of the nozzle.

The following examples illustrate the present invention in more detail. However, it should be understood that the present invention is not limited by these examples.

Preparation of the nano-coated nozzle

Example 1

1 mol of Tetra-ethyl-ortho-silicate was dissolved in 50 mol ethanol. 0.01 mol Per-flour-octyl-triethoxy-silane was added under stirring. 4 mol of water, acidified to a pH of 4 by adding HC1, were added to the solution. After being kept under stirring for 48 hours, the coating was applied via spray coating. The coating liquid, remaining inside the channel of the nozzle, was blown out with compressed air subsequently. The final curing is done at elevated temperatures such as 80°C for at least 30 minutes.

In the example, the water contact angle of the coating is 115°, the thickness of the coating is 1 μπι and the type of the nozzle is Vectra A230 706/906.

Example 2

An organo-polymeric film, such as a partially fluorinated silicon-oxide-epoxy-hybrid-polymer with hydrophobic properties generating water contact angles of 117° is used as the coating of the nozzle.

The uncoated nozzle is placed on a special nozzle holder, allowing air to be blown or drawn through the channel of the nozzle. The nozzle is put into the coating liquid and, similar to a syringe, the coating liquid is drawn into the channel. After a few seconds, the liquid is slowly blown out of the channel leaving a thin film on the surface of the channel, while the nozzle is slowly removed from the coating liquid leaving a thin film on the outer surface of the nozzle.

Example 3

The material for the coating is a water-bourne silicon-based hybride-polymer coating-solution and the type of the nozzle is Vectra A230 706/906. The coating is applied via spraying. After the outside of the nozzle as well as the inside of the channel have been covered with the coating liquid, the additional material, remaining inside the channel has to be removed by blowing with compressed air in order to avoid a jamming of the nozzle. The final curing is done at elevated temperatures such as 80°C for at least 30 minutes.

By the above preparation process, the water contact angle of the coating is 117°. The thickness of the coating is 2μπι.

Evaluation of the nozzle

The performance of the nozzle according to the invention can be evaluated by measurement of vacuum error and vacuum offset between pick-up open and pick-up close.

Vacuum error is the most direct way to evaluate the nozzle's quality and stability in the production line. However, vacuum errors can be caused by nozzle, feeder or plunger. Therefore, vacuum errors only can be used as a reference, since there are many factors, for example, influenced by the feeder or plunger.

Vacuum offset between pick-up open and close is also a direct way to evaluate the nozzle's quality and stability in the production line. The bigger value of the vacuum offset between pick-up open and pick-up close, the better quality and stability the nozzle has.

Experimental Example 1

The vacuum error and vacuum offset between pick-up open and pick-up close of the nozzle as prepared in Example 3 (nano in Table 1) and a standard Vectra A230 706/906 nozzle are measured respectively. The results are shown in Figures 1 and 2, as well as Table 1.

Table 1 :

Experimental Example 2

Locations of the nozzle as prepared in Example 3 and the standard Vectra A230 706/906 nozzle are exchanged. Then the vacuum error and vacuum offset between pick-up open and pick-up close of the nozzle as prepared in Example 3 and the standard Vectra A230 706/906 nozzle are measured respectively. The results are shown in Figures 3 and 4, as well as Table 2.

Table 2

From the above results, it is obvious that the coated nozzle according to the invention shows an improved quality and stability.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

What is claimed is:

1. A nozzle for electronic assembly, wherein the nozzle is coated with an anti-adhesive coating.

2. The nozzle according to claim 1, wherein the nozzle is fully coated or partly coated.

3. The nozzle according to claim 1, wherein the thickness of the anti-adhesive coating is ΙΟηηι-ΙΟμηι and/or no more than 5% of the diameter of the channel of the nozzle.

4. The nozzle according to anyone of the preceding claims, wherein the electrical resistivity of the coating is less than l x l O¹⁰ Ohm/square.

5. The nozzle according to anyone of the preceding claims, wherein the water contact angle of the coating is in the range of 60-120°.

6. The nozzle according to claim 4, wherein the water contact angle of the coating is higher than 90°.

7. The nozzle according to anyone of the preceding claims, wherein the coating comprises an organo-polymeric film with hydrophobic properties.

8. The nozzle according to claim 7, wherein the organo-polymeric film comprising at least one functional group of alkyl, cycloalkyl, aryl and partially fluorinated alkyl chains.

9. The nozzle according to claim 8, wherein the at least one functional group is selected from the group consisting of alkyl-groups with C1 -C8 chain length, linear or branched; cycloalkyl groups with C3-C8; aromatic groups with C6-C8; and fluorinated alkyl groups with C3-C20.

10. The nozzle according to anyone of claims 1-5, wherein the anti-adhesive coating is prepared by sol-gel process.

11. The nozzle according to claim 10, wherein the sol-gel process includes those processes in which metal-precursor material is hydrolyzed and subsequently goes through a condensation step.

12. The nozzle according to claim 11, wherein the metal-precursor material is metal halogenide or metal-alkoxide.

13. The nozzle according to claim 12, wherein the metal is silicon, aluminum, titanium or zirconium.

14. The nozzle according to claim 11, wherein at least one functional group selected from the group consisting of alkyl-groups with C1 -C8 chain length, linear or branched; cycloalkylgroups with C3-C8; aromatic groups with C6-C8; and fluorinated alkyl groups with C3-C20 is incorporated into the coating.

15. The nozzle according to claim 14, wherein the at least one functional group is linked to the metal-precursor material or is added during the hydrolysis-condensation process.

16. The nozzle according to any one of the preceding claims, wherein the coating further comprises electrically conductive particles or fibers.

17. The nozzle according to claim 16, wherein the particles or fibers are made of carbon, metals or conductive metal oxides in nano-scale.

18. The nozzle according to any one of the preceding claims, wherein the coating further comprises inorganic particles in nano-scale.

19. The nozzle according to any one of the preceding claims, wherein color is incorporated in the coating by using conventional organic dye-systems, pigments or metal-organic particles.

20. A method for preparing the nozzle according to any one of claims 1-19, comprising a wet chemical coating procedure.

21. The method according to claim 20, comprising sol-gel process, spraying process or dipping process.

22. The method according to claim 20, wherein the coating liquid is removed from the nozzle by blowing with compressed air leaving only a thin coating film is left on the surface of the nozzle.