CA2256418A1 - Chambers for promoting surface adhesion under vacuum and methods of using same - Google Patents
Chambers for promoting surface adhesion under vacuum and methods of using same Download PDFInfo
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- CA2256418A1 CA2256418A1 CA 2256418 CA2256418A CA2256418A1 CA 2256418 A1 CA2256418 A1 CA 2256418A1 CA 2256418 CA2256418 CA 2256418 CA 2256418 A CA2256418 A CA 2256418A CA 2256418 A1 CA2256418 A1 CA 2256418A1
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- layer
- adhesion promotion
- vacuum chamber
- surface adhesion
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/60—Deposition of organic layers from vapour phase
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/02—Pretreatment of the material to be coated
- C23C16/0272—Deposition of sub-layers, e.g. to promote the adhesion of the main coating
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- Chemical Kinetics & Catalysis (AREA)
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- Application Of Or Painting With Fluid Materials (AREA)
Abstract
In one aspect, the present invention provides a method of depositing a layer of surface coating material. The method is carried out in a vacuum chamber and comprises the steps of depositing a layer of surface adhesion promotion material on a surface of a substrate; and depositing a layer of a surface coating material on a surface of the layer of the surface adhesion promotion material so that the layer of surface coating material has an adhesion of greater than about 3.75 pounds per inch according to the hesiometry test. In another aspect, the present invention provides an article of manufacture. The article comprises a substrate, a layer of surface adhesion promotion material and a layer of a surface coating material. The layer of surface adhesion material is supported by the substrate, and the layer of a surface coating material is supported by the layer of surface adhesion promotion material. The surface coating material has an adhesion of greater than about 3.75 pounds per inch as measured by the hesiometry test. In a further aspect, the present invention provides a vacuum chamber. The chamber comprises a body, a reservoir and plumbing. The body has an orifice with a diameter of less than about 75 mils disposed therein. The reservoir is capable of containing a surface adhesion material. The plumbing is disposed along the perimeter of the orifice of the body to physically connect the plumbing to the body. The plumbing is also physically connected to the reservoir. The plumbing has an orifice disposed therein such that the reservoir is in fluid communication with the body.
Description
CA 022~6418 1998-ll-26 W O 97/45209 PCTrUS97/09412 C~IAMl'~l~RS FOR PROMOTING SURFACE ADHESION UNDF,R VACUUM AND
l\~ETHODS OF USING SAME
B~CKGROUND
., 1. Field of the Invention The present invention relates generally to chambers for promoting surface adhesion under vacuum as well as methods of using same, and more particularly to such charnbers and methods which may be used with surface adhesion promotion materials as well as surface coating 0 materials.
l\~ETHODS OF USING SAME
B~CKGROUND
., 1. Field of the Invention The present invention relates generally to chambers for promoting surface adhesion under vacuum as well as methods of using same, and more particularly to such charnbers and methods which may be used with surface adhesion promotion materials as well as surface coating 0 materials.
2. Backgrolm~l ofthe Invention In many applications, it is desirable to provide a layer of a surface coating material onto a surface to reduce the chemical reactivity of the surface. For example, subcutaneous probes may ls be formed from materials that are capable of reacting with various chemical species within the human body, but it is desirable to prevent these chemical reactions from taking place. Therefore, it is advantageous to coat such subcutaneous probes with a surface coating material that renders the probes relatively chemically inert.
In recent years, vacuum deposition has become a popular method of applying surface 20 coating m~t~ri~ because this technique results in layers of surface coating materials that are inert and have acceptable adhesion. However, under some circllm~t~nces, a surface coating m~t~ ri~l may not readily bond to a surface of interest, resulting in comparatively poor adhesion of the surface coating material to the surface. As a result, several methods have been developed to increase the adhesion of the surface coating m~ri~l by applying a surface adhesion promotion 25 material onto the surface prior to depositing the surface coating mzlt~risl U.S. Patent No. 3,600,216 discloses a method of applying surface adhesion promotion m~tçri~ to surfaces using silane primers. According to this technique, the surface of a subskate is keated with a solution produced by dissolving the surface adhesion promotion material in a solvent. The surface of the subskate is then exposed to the solution by dipping. The treated 30 surface is subsequently dried to evaporate the soivent and provide the layer of surface adhesion promotion material. Next, the subskate is placed in a vacuum chamber and the vacuum chamber is pumped down. After the vacuum chamber reaches its base pressure, the surface is exposed to the surface coating m~teri~l CA 022~6418 1998-ll-26 W O 97/45209 PCTrUS97/09412 While this technique may have some success in producing layers of surface adhesion promotion materials on surfaces, this method has several drawbacks. The use of solvents can involve health and safety factors as well as storage and disposal concerns, resulting in increased cost. Furthermore, since the application of the surface adhesion promotion material is done outside the vacuum charnber, this technique is labor intensive, resulting in decreased convenience and increased costs.
C~n~tliz-n Patent No. 1,119,056 discloses a method of applying a surface adhesion promotion material, such as gamma-methacrylo~y~lo~ylll;lllethoxysilane (hereinafter '~A174"), under vacuum conditions. According to this technique, the Al 74 is stored in a reservoir that is lo connt?ctecl the vacuum chamber through plumbing having a valve. The surface of interest is placed in the vacuum chamber, and the vacuum chamber is pumped down with the valve closed.
The valve is then opened to allow to the A174 to enter the vacuum chamber while m~int~;nin~;
the A174 at or below room temperature. The valve is subsequently closed, and the surface coating material is deposited.
The inventor of the present app~ication has found that the method disclosed in C~n~ n Patent No. 1,1 19,056 may be limited to relatively small sized vacuum chambers which are usually only a~ o~3~iate for use in a laboratory setting. In particular, when this method is used with vacuum chambers designed for comrnercial use (i.e., vacuum chambers having a body with a volume of at least about 144 cubic inches), ~ the Al 74 at or below room tt;ln~ dl~lre 20 precludes the A174 from evaporating in sufficient quantity to become adequately distributed throughout the vacuum chamber to forrn an effective coating on the surface. Instead, the A 174 has been observed to condense in the plumbing which connects the reservoir to the vacuum chamber, and the A174 either forms an unevenly distributed coating on the surface or does not bond to the surface at all. As a result, the subsequently deposited surface coating material 25 demonstrates inferior adhesion, rendering this method inal,plol,liate for commercial use. In addition, because of the limitation on the size of the vacuurn chamber with which this method can be effectively used, the substrates ~p~ iate for use with this method are limited to having an area of at most about 100 square inches.
Therefore, it is desirable to provide commercially useful vacuum chambers that can be 30 used to form layers of surface adhesion promotion materials on surfaces such that subsequently deposited surface coating mzlteri~l~ exhibit improved adhesion. It is further desirable to provide methods of using these vacuum charnbers to provide layers of coating m~f~ri~l~ having improved , CA 022~6418 1998-ll-26 W O 97/45209 3 PCTrUS97/09412 adhesion.
SUMM~RY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vacuurn chamber capable s of being used in the formation of layers of surface coating materials that exhibit improved adhesion.
It is another object of the present invention to provide a method of ylc~ hlg such layers of surface coating m~teri~l~
It is a further object of the present invention to provide a substrate which supports a layer 10 of surface adhesion promotion material which, in turn, supports a layer of surface coating material such that the surface coating material exhibits improved adhesion.
In one illustrative embodirnent, the present invention provides a method of depositing a layer of surface coating m~tPri~l The method is carried out in a vacuum chamber and comprises the steps of depositing a layer of surface adhesion promotion material on a surface of a substrate, 15 and depositing a layer of a surface coating m~tPri~l on a surface of the layer of the surface adhesion promotion m~teri~l so that the layer of surface coating material has an adhesion of greater than about 3.75 pounds per inch according to the hesiometry test.
In another illustrative embodiment, the present invention provides an article ofm~nllfiq-~ture. The article comprises a substrate, a layer of surface adhesion promotion m~tPris~l 20 and a layer of a surface coating m~tPri~l The layer of surface adhesion material is supported by the substrate, and the layer of a surface coating m~tPri~l is supported by the layer of surface adhesion promotion ms)tPri~l The surface coating m~t~ri~l has an adhesion of greater than about 3.75 pounds per inch as measured by the hesiometry test.
In a further illustrative embodiment, the present invention provides a vacuum chamber.
2s The chamber comprises a body, a reservoir and plumbing. The body has an orifice with a diameter of less than about 75 mils disposed therein. The reservoir is capable of co,.~ a surface adhesion material. The plumbing is disposed along the perimeter of the orifice of the body to physically connect the plumbing to the body. The plumbing is also physically connected to the reservoir. The plumbing has an orifice disposed therein such that the reservoir is in fluid 30 cot..~ l.ic~tion with the body.
CA 022~6418 1998-11-26 W O 97145209 PCTrUS97/09412 l~TFF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of one embodiment of a vacuum charnber according to the present invention;
Fig. 2 is cross-sectional view of one embodiment of a substrate having disposed thereon a 5 layer of surface adhesion promotion material which has disposed thereon a layer of surface coating material, and Fig. 3 is a schematic representation of one embodiment of an d~ardlus used for performing hesiometry tests according to the present invention.
o DFTAILED DESCRIPTION
In one aspect, the present invention relates to vacuum chambers that can be used to form layers of surface adhesion promotion materials on surfaces such that subsequently deposited surface coating materials exhibit improved adhesion. Fig. 1 depicts one embodiment of a vacuum chamber 10 which includes adhesion promotion deposition C~ll~llnent 11. According I s to the present invention, COlll~ ent 1 1 is designed to allow a relatively even distribution of a sur~ace adhesion promotion material to be disposed onto the surface of a substrate 28, located ~,vithin the body 18 of chamber 10, such that a subsequently deposited layer of a surface coating material e~hibits improved adhesion.
Compartment 11 includes a weldment stub 12 which is welded to vacuum chamber 10 around the perimeter of a hole 14 which is drilled into body 18 of chamber 10. A reservoir 16, cont:~inin~ A174, is in fluid culllll~ ication with body 18 orifice 22 and plumbing 20 which is connected to stub 12. Heating apparatus 26, which is held in place by mounting brackets (not shown~, surrounds reservoir 16. Pump exhaust 31 of vacuurn charnber 10 is disposed such that ~xh~llet 31 is located in a diagonal direction across chamber 10 as far as possible from hole 14.
2s In addition, it is to be noted that reservoir 16 is in a high position relative to exhaust 31.
With this arrangement, a layer of Al 74 is coated onto the surface of substrate 28 as follows. The pressure of vacuum chamber 10 is reduced to its minimllm pressure using standard methods as known to those skilled in the art. The ~ dlLU~ of reservoir 16 is subsequently increased from room temperature to about 190~C by use of heating apparatus 26. At this 3~ temperature, the A174 is evaporated from reservoir 16 in a controlled fashion. The evaporated Al 74 then travels through plumbing 20 to orifice 22 and passes through orifice 22 to enter body 18 of chamber 10. Since the A174 was evaporated at an elevated l~lllp~ldlule, it contains a large CA 022~6418 1998-ll-26 W O 97!45209 PCT~US97/09412 amount of kinetic energy relative to A174 at or below room temperature, so the A174 easily travels within body 18 and is exposed to a substantial portion of the volume of body 18.
Furthermore, because substrate 28 is located the m;1xi~ diagonal distance from hole 14, the density of the evaporated A174 is approximately homogeneous in the region around the surface s of substrate 28. Thus, the A174 which deposits onto the surface of substrate 28 forms a relatively evenly diskibuted layer. It is believed that the formation of a relatively evenly distributed layer of surface adhesion promotion material on the surface of substrate 28 allows a subsequently deposited layer of surface coating material to exhibit improved adhesion. It is to be noted that, during the process of deposition of A174 on the surface of substrate 28, the vaporized 10 A174 may also coat portions of the inner walls of various parts of vacuum chamber 10.
It has been unexpectedly found that vacuum chamber 10 can be pumped down to its minimum pressure without valving off reservoir 16 which contains A174 at room temperature.
In particular, contrary to the conventional wisdom, the vapor pressure of A174 has been found to be low enough that evaporation of A174 does not prevent vacuum chamber 10 from re~ching its 1S minimum p~ ul~ when the A174 is held at room tt;~ Lule. It is believed that orifice 22 is capable of reducing the conductance of A174 from reservoir 16 to body 18 which assists chamber 10 in obtaining its minimllm pressure without complications due to the evaporation of A174.
One common problem with deposition steps in vacuum chambers is associated with the 20 steps of pumping out and subsequently valving off the reservoir and associated plumbing prior to pumping down the body of the vacuum chamber. In many instances, an operator of a vacuum chamber forgets to first pump out the reservoir and associated plumbing prior to valving them off. As a result, when the valve to the reservoir and associated plumbing is opened after ~ulllpillg down the main charnber, the vacuum chamber pressure increases dramatically. This 25 can lead to venting of the vacuum chamber, destruction of vacuurn chamber equipment (e.g., pressure sensitive electronics stored within the vacuum chamber) and/or co~ " .i ~ ion of the substrate surface. This results in a loss of a substantial amount of labor and resources, increasing the costs associated with this process. Therefore, by elimin~tin~ the need of a valve between reservoir 16 and body 18, vacuum chambers in accordance with the present invention can 30 provide a more efficient and less expensive process.
While one particular arrangement of adhesion promotion deposition C<)~ lllllent 11 has been disclosed herein, the present invention is intPn~led to include other arrangements. The CA 022~6418 1998-11-26 W O 97/45209 6 PCTrUS97/09412 particular arrangemcnt of the components of Cul~ ent 1 1 iS limited only in that compartment 11 should be capable of producing a sufficiently evenly distributed layer of surface adhesive material on the sur~ace of substrate 28 such that a subscquently deposited layer of surface coating material exhibits improved adhesion.
s For example, in embo(lim~nt~ in which body 18 of chamber 10 is relatively long and horizontal, reservoir 16 should be located near orifice 33 of pyrolysis chamber 19 (described below).
Reservoir 16 may be any vacuum compatible container that is capable of housing any surface adhesion promotion material. Reservoir 16 should also be chemically inert to the surface 10 adhesion promotion material contained therein at or below the temperature used to deposit the surface adhesion promotion material. One example of such a reservoir is a 100 mL 304 stainless steel tube.
Heating a~a,dLus 26 may be any device that is capable of heating reservoir 16 and the surface adhesion material contained therein in a controlled fashion. Apparatus 26 may also be capable of being mounted to chamber 10 by brackets 24a and 24b, or the like, while supporting reservoir 16. In certain embodiments, ~paldlus 26 may surround reservoir 16. One example of such a heating ~paldlus is a small oven.
Plumbing 20 may be formed from any vacuum compatible material that is capable offluidly connecting reservoir 16 to hole 14. Plumbing 20 should also be chemically inert to A174.
20 In one embodiment, plumbing 20 is formed from a Viton~ O-ring, a 1/8" male coupling and a VCO female connector.
Hole 14 and weldment stub 12 may have any size diameter so long as they are capable of being welded together to form a vacuum tight seal that allows reservoir 16 to be fluidly connected to body 18. Since stub 12 typically is available in predetermined sizes (e.g., 1/8"), it 25 may be advantageous for hole 14 to have a ~ m~ter which corresponds to one these predetermined sizes. In one embodiment, hole 14 and weldment stub 12 each have a diameter of about 118". In certain embodiments, weldment stub 12 may be replaced by an equivalent connecting device, such as a 1/8" Union or a female fractional tube adjuster.
It is believed that orifice 22 may reduce the conductance of vaporized surface adhesion 30 promotion material from reservoir 16 to body 18 such that, subsequent to being heated by a~dldtus 26, the flow of vaporized surface adhesion promotion material into body 18 produces a relatively homogeneous density distribution of vaporized surface adhesion promotion material CA 022~64l8 l998-ll-26 W 097/45209 PCT~US97/09412 throughout portions of body 18. This allows the vaporized surface adhesion promotion material to form a relatively evenly distributed layer on the surface of substrate 28, allowing a subsequently deposited layer of surface coating m~tf~ri~l to exhibit improved adhesion.
Therefore, orifice 22 may be of any size so long as orifice 22 is capable of restricting the flow of S evaporated surface adhesion promotion material from reservoir 16 to body 18 so that the surface adhesion material forms a relatively evenly distributed layer on the surface of substrate 28 and so that a subsequently deposited layer of surface coating material exhibits improved adhesion. It has been found that, in some embodiments, orifice 22 is ineffective if it has a diameter greater than about 100 mils (lmil = 0.001"). Hence, for such embodiments, orifice 22 should have a lo diameter of less than about 75 mils. In one embodiment, orifice 22 has a diameter of about 16 mils.
Vacuum chamber 10 may be any vacuum chamber which is capable of being modified to include C~ .nent 11. In addition, chamber 10 should include surface coating deposition com~ l.ent 13 (Fig. 1). Preferably, body 18 of chamber 10 has a volume of at least about 144 15 cubic inches, more preferably at least about 288 cubic inches and most preferably at least about 432 cubic inches. Such vacuum chambers include, but are not limited to, the following commercially available vacuum chambers, each of which is available from Specialty Coating Systems, Inc, Clear Lake, W~: model 1050 (part no. 2169800), model 1030 (part no. 216802);
model 2090 (part no. 2169803); model 2010 (part no. 2169804); and model 2060 (part no.
20 BM02616).
As shown in Fig. 1, surface coating deposition compartment 13, which is a~n)pliate for use with the parylene family of surface coating materials, should include vaporization chamber 15, pyrolysis chamber 17 and post-pyrolis chamber 19. Vaporization chamber 15 evaporates the parylene dimer, pyrolysis chamber 17 cleaves the parylene dimer to form a gas including 25 parylene monomer, and post-pyrolysis chamber includes at least one cooled baffle to remove any parylene dimer from the gas. Such deposition cOlllp~ lments are disclosed in commonly assigned U.S. Patent Serial No. 08/549,087 which is herein incorporated by reference. While certain embodiments of COl~ l Llllent 13 have been disclosed herein, it is to be understood that conlpal~ll,ent 13 is not limited by these embo-liment~ ~ompartment 13 may include any 30 combination of devices that are capable of acting in unison to deposit a layer of surface coating mslt~ri~l onto a layer of surface adhesion promotion material disposed on the surface of substrate 28. Such co~ ~Lll,ents are known to those skilled in the art and are inten~led to be within the CA 022~6418 1998-ll-26 W O 97t~5209 8 PCTrUS97/~9412 scope of the present invention.
Methods of depositing a layer of surface coating m~t~.ri~l using compartment 13 include the steps of vaporizing the parylene dimer, pyrolizing the parylene to form a gas including monomers of the parylene, passing the gas through at least one cooled baffle to remove any s parylene dimer in the gas, and depositing the monomer of parylene on the layer of the surface adhesion promotion material which is disposed on the surface of substrate 28. Such methods are described in, for example, U.S. Patent Application Serial No. 08/549,087. Other methods of depositing a layer of surface coating material are known to those skilled in the art and are int~n~le-l to be within the scope of the present invention.
Fig. 2 depicts a cross-sectional view of one embodiment of substrate 28 having a surface 30 on which a layer 32 of surface adhesion promotion material is deposited. A layer 34 of surface coating material is disposed on layer 32. Surface 30 may have any area so long as layer 32 can be deposited thereon such that subsequently deposited layer 34 exhibits improved adhesion. While ~ig. 1 depicts chamber 10 having one substrate 28 disposed therein, it is to be 15 understood that chamber 10 may have a plurality of subskates disposed therein. In certain embodiments in which a plurality of substrates are disposed within chamber 10, the total surface area of the substrates is preferably at least about 100 square inches.
According to the present invention, substrate 28 may be any object or body having surface 30 onto which a surface adhesion promotion material may be deposited by at least one of 20 the methods of the present invention. Substrate 28 may be formed from organic materials or inorganic materials including, for example, polymeric materials, semiconductor materials, metallic materials, oxides of metallic mzltPri~l~ and the like. Such organic m~tfxi~l~ and inorganic materials include, but are not limited to, all.,--i.-l.,.~, iron, steel, molybdenum, al..,.li..l.lll oxide, titanium oxide, lead oxide, copper oxide, iron oxide, beryllium oxide, 25 m~n~n~se oxide, tlln~cten oxide, tantalum oxide, v:~n~ m oxide, silicones, natural rubbers, plastic composites, cellulosic m5lt~ri~l~, epoxy-co~ g compounds, thermosetting compounds, thermoplastic compounds, silicon oxide (e.g., sand, fly ash, hydrated silica, silica, quartz, aerogel, xerogel, fumed silica) and the like. Substrate 28 may also be formed from a vacuum compatible liqu;d. By "vacuum compatible" it is herein meant to refer to a material that 30 has a vapor pressure at room temperature such that the minimllm ])L~S~ c; to which a vacuum chamber can be pumped is independent of the presence of the vacuum compatible material. One exarnple of such a vacuum compatible liquid is A174. Other such vacuum compatible materials CA 022~6418 1998-ll-26 W O 97/45209 9 PCT~US97/09412 will be a~p~elll to those skilled in the art and are intended to be within the scope of the present mventlon.
In certain embodiments, substrate 28 may be a printed circuit board, a silicon wafer, paper, a key pad, a catheter, a pacemaker cover, a subcutaneous probe, a bird feather, a silicone , 5 O-ring or the like.
Layer 32 of surface adhesion promotion material may be formed from any vacuum compatible material that is capable of ~im~ n~ously bonding to surface 30 and layer 34 such that layer 34 has an adhesion of greater than about 3.75 pounds per inch (Ibs/in) as measured according to the hesiometry test, more preferably at least about 5 lbs/in and most preferably at lo least about 8 lbs/in.
As used herein, the term "hesiometry test" refers to a test which was developed by W. K.
Asbeck, Paint and Varn~sh Prod. p. 23,1970. Fig.3 represents the setup used in the hesiometry test. Substrate 30 is placed on a motorized stage 40 which moves in a direction indicated by the arrow. As stage 40 moves, a knife-like device 42 cuts ch~nnel~ in layers 32/ 34. Device 42 is lS pushed through the interface between substrate 28 and layers 32/34, and the horizontal force (Fh)is measured by a transducer 44. Substrate 28 is returned to its starting point and run again so that the contribution due to the frictional force between device 42 and surface 30 can be measured. The difference between the horizontal force and the frictional force is equal to the adhesion of layer 34.
Although layer 32 of surface adhesion promotion material may be formed from any m~eri~l having the properties discussed above, layer 32 is preferably formed from an organosilane, more preferably from an alkoxysilane, and most preferably from A174 (i.e., gamma-methacryloxy,~l~,pyltrimethoxysilane).
In some embo~limenl~, layer 32 is formed from a multi-layer of molecules of surface 25 adhesion promotion m~t~ri~l In these embodiments, some molecules of surface adhesion promotion material bond with surface 30 while other molecules of surface adhesion promotion m~t~ri~l do not bond with surface 30. A "bond" as used herein refers to any combination of chemical bonding, physical entanglement or physical bonding, such as hydrogen bonding or van der Waals bonding.
For emborliment~ in which layer 32 is formed from a multi-layer of molecules of surface adhesion promotion material, layer 32 should have a thickn~,cs of at least about 20 ~ as measured CA 022~6418 1998-11-26 W O 97/45209 10 PCT~US97/09412 using a ~ua~tz crystal thickness monitor or an equivalent device. It is to bc noted that if layer 32 is less than about 20 ~ thick, layer 34 may not have sufficient adhesion.
In some embo~1iment~, molecules of surface adhesion promotion materials have a polar end and a nonpolar end. For example, Al 74 has a polar end (trimethoxy) and a nonpolar end s (methacryloxy). While it is not fully understood, it is believed that, when such surface adhesion promotion materials are used with surfaces that are more polar than the nonpolar end of the molecules of the surface adhesion material, the polar ends of the molecules of the surface adhesion mslt~ri~l bond to the surface and the nonpolar ends of the molecules of the surface adhesion material are directed away from the surface. With this configuration, the molecules of I o the surface coating material are exposed to the nonpolar ends of the molecules of the surface adhesion mslt~ri~l rather than the c()~ ,aldtively polar surface. If the surface molecules of the surface coating material are nonpolar relative to the surface, the surface molecules of the surface coating material may bond more readily to the nonpolar end of the molecules of the surface adhesion material than the relatively polar surface.
Layer 34 of surface coating material may be formed ~om any mslt~ri~l th~t is capable of bonding to layer 32 and which is capable of forming a layer of material that is chemically inert relative to surface 30. Such m~t( ri~l~ are known to those skilled in the art and include, for exarnple, poly-p-xylylene materials. An illustrative and nonlimiting list of such poly-p-xylylenes includes parylene D, parylene N, parylene C and octafluoro-~2,2] paracyclophane such as disclosed in commonly assigned U.S. Patent Application Serial No. 08/544,831 which is hereby incorporated by reference.
In certain embo~1iment~, layer 34 may have dirr~ l physical l~lop~lies than surface 30.
For example, layer 34 may have a different rollghness, electrical conductivity and/or therrnal conductivity than surface 30.
2s The following examples are int~n~lecl for illustrative purposes and is not to be construed as limiting.
F.x~n~le 1 A substrate without a layer of surface coating m~t~ri~l was deposited on a substrate as follows. A borosilicate substrate was cleaned by hand washing with a 2% solution of Microsoap~ in water. The substrate was rinsed with de-ionized water and placed in an autoclave.
The substrate was heated in the autoclave at 250~F for about one hour in the presence of de-CA 022~6418 1998-ll-26 W O 97/45209 ~ PCTrUS97/09412 ionized water. The substrate was removed from the autoclave, and any rem~inin~ liquid was blown off with ul~1~u1~ nitrogen gas. The substrate was then vacuum baked at a temperature of about 50~C at a pressure of less than 100 mTorr.
The cleaned substrate was then coated with parylene C by f1rst vaporizing the solid dimer of parylene C. The methylene-methylene bonds of the parylene were then cleaved in the pyrolosis chamber at a temperature of about 680"C to yield monomers of the parylene C. The monomer was subsequently deposited onto the layer of A174. Upon deposition, the monomers of A174 polymerized. The coated substrate was removed from the vacuum chatnber stressed by pl~ menf in an autoclave for a time period of about one hour at a temperature of about 250~F in 1 o the presence of de-ionized water.
The adhesion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average adhesion was measured to be about 0.25 Ibs/in according to the hesiometry test.
Ex~mple 2 A substrate having a layer of surface adhesion promotion m~t( ri~l deposited in sllhst~nti~l accordance with the method disclosed in U.S. Patent No. 3,6~0,216 and a further layer of a surface coating m~t~.ri~l was prepared as follows. A borosilicate substrate as described in Exarnple 1 was cleaned according to the method disclosed in Example 1. A layer of A174 was applied to the surface of the borosilicate substrate by dipping the in a solution of 0.5% A174, 49.75% de-ionized water and 49.75% isop1vp~ulol. This dipping procedure was carried out for about 15 min~ltes. The substrate was then dried for about 15 minutes and subsequently rinsed with neat iso~ ol. The substrate was next air dried for about one half hour.
2s The layer of A174 provided by the above method was coated with parylene C~ and stressed as described in Example 1. The a&esion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average adhesion was measured by the hesiometry test to be about 2.25 Ibs/in.
CA 022~6418 1998-ll-26 W O 97145209 -12- PCT~US97/09412 Fx~rr~le 3 A substrate with a layer of surface adhesion promotion material was prepared as follows.
A borosilicate substrate as described in Example 1 was cleaned according to the method disclosed in Example 1. A borosilicate substrate as described in Example 1 was cleaned s according to the method of Example 1. The substrate was then placed in a vacuum chamber, and a layer of Al 74 was applied to the surface of the ~ub~Lldte under vacuum conditions. The coated subskate was then removed from this vacuum chamber and transferred to a second vacuum chamber in accordance with methods described herein (i.e., the coated substrate was exposed to atmospheric conditions prior to the deposition of the surface coating material).0 The layer of Al 74 was then coated with parylene C and stressed as described in Example 1. It is to be noted that the coated substrate was exposed to a substantial amount of dynarnic pumping in the second vacuum chamber prior to the deposition of the surface coating material.
The adhesion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points.
15 The average adhesion was measured by the hesiometry test to be about 3.75 Ibs/in.
Fx~ml?le 4 A borosilicate ~ub~ as described in Example 1 was cleaned according to the method of Example 1. The substrate was then placed in a model 1050 parylene generation vacuum 20 chamber (part no. 2169800, Specialty Coatings Systems, Inc., Clear Lake, WI) which was modified as shown in Fig. 1. The ~l~s~ule of the chamber was reduced to about 50 m;lliTorr.
About 2.5 mL of Al 74 was vaporized at a t~ d~ of about 190 ~C, and the thickness of the coating of Al 74 was monitored using a quartz crystal thickness monitor (Model No. TM 100, available from Maxtek). The layer of Al 74 was then coated with parylene C and stressed as 25 described in Example 1. The layer of A174 was about 227 ~ and the layer of parylene C was from about 4000 A to about 5000 ~. Adhesion of the coating of parylene C m~tt~n~l was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average a&esion was measured to be about 8 lbs/in according to the hesiometry test.
As indicated by Example 1, when a layer of Al74 is not applied to the borosilicate surface prior to the deposition of the parylene material, the parylene material has the poorest CA 022~6418 1998-11-26 W O 97/45209 -13- PCT~US97109412 adhesion. Furthermore, when a layer of A174 is applied from solution (Fx~mple 2), the subsequently deposited layer of parylene material exhibits poor adhesion. In addition, when the A174 coated borosilicate substrate is exposed to atmospheric conditions prior to the deposition of the parylene material (Example 3), the layer of parylene material exhibits inferior adhesion.
~, 5 However, when the process of the present invention is used to apply the layers of Al 74 and parylene material to the borosilicate substrate (Example 4), the layer of parylene material exhibits better adhesion than when the methods of Fxs~mples 1-3 are used.
Having thus described certain embo~liment~ of the present invention, various improvements, modifications and alterations will be obvious to those skilled in the art. Such lo improvements, modifications and alterations are jn~nded to be within the spirit and scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended as limitin~. The invention is limited only as defined in the following the claims and equivalents thereto.
What is claimed is:
In recent years, vacuum deposition has become a popular method of applying surface 20 coating m~t~ri~ because this technique results in layers of surface coating materials that are inert and have acceptable adhesion. However, under some circllm~t~nces, a surface coating m~t~ ri~l may not readily bond to a surface of interest, resulting in comparatively poor adhesion of the surface coating material to the surface. As a result, several methods have been developed to increase the adhesion of the surface coating m~ri~l by applying a surface adhesion promotion 25 material onto the surface prior to depositing the surface coating mzlt~risl U.S. Patent No. 3,600,216 discloses a method of applying surface adhesion promotion m~tçri~ to surfaces using silane primers. According to this technique, the surface of a subskate is keated with a solution produced by dissolving the surface adhesion promotion material in a solvent. The surface of the subskate is then exposed to the solution by dipping. The treated 30 surface is subsequently dried to evaporate the soivent and provide the layer of surface adhesion promotion material. Next, the subskate is placed in a vacuum chamber and the vacuum chamber is pumped down. After the vacuum chamber reaches its base pressure, the surface is exposed to the surface coating m~teri~l CA 022~6418 1998-ll-26 W O 97/45209 PCTrUS97/09412 While this technique may have some success in producing layers of surface adhesion promotion materials on surfaces, this method has several drawbacks. The use of solvents can involve health and safety factors as well as storage and disposal concerns, resulting in increased cost. Furthermore, since the application of the surface adhesion promotion material is done outside the vacuum charnber, this technique is labor intensive, resulting in decreased convenience and increased costs.
C~n~tliz-n Patent No. 1,119,056 discloses a method of applying a surface adhesion promotion material, such as gamma-methacrylo~y~lo~ylll;lllethoxysilane (hereinafter '~A174"), under vacuum conditions. According to this technique, the Al 74 is stored in a reservoir that is lo connt?ctecl the vacuum chamber through plumbing having a valve. The surface of interest is placed in the vacuum chamber, and the vacuum chamber is pumped down with the valve closed.
The valve is then opened to allow to the A174 to enter the vacuum chamber while m~int~;nin~;
the A174 at or below room temperature. The valve is subsequently closed, and the surface coating material is deposited.
The inventor of the present app~ication has found that the method disclosed in C~n~ n Patent No. 1,1 19,056 may be limited to relatively small sized vacuum chambers which are usually only a~ o~3~iate for use in a laboratory setting. In particular, when this method is used with vacuum chambers designed for comrnercial use (i.e., vacuum chambers having a body with a volume of at least about 144 cubic inches), ~ the Al 74 at or below room tt;ln~ dl~lre 20 precludes the A174 from evaporating in sufficient quantity to become adequately distributed throughout the vacuum chamber to forrn an effective coating on the surface. Instead, the A 174 has been observed to condense in the plumbing which connects the reservoir to the vacuum chamber, and the A174 either forms an unevenly distributed coating on the surface or does not bond to the surface at all. As a result, the subsequently deposited surface coating material 25 demonstrates inferior adhesion, rendering this method inal,plol,liate for commercial use. In addition, because of the limitation on the size of the vacuurn chamber with which this method can be effectively used, the substrates ~p~ iate for use with this method are limited to having an area of at most about 100 square inches.
Therefore, it is desirable to provide commercially useful vacuum chambers that can be 30 used to form layers of surface adhesion promotion materials on surfaces such that subsequently deposited surface coating mzlteri~l~ exhibit improved adhesion. It is further desirable to provide methods of using these vacuum charnbers to provide layers of coating m~f~ri~l~ having improved , CA 022~6418 1998-ll-26 W O 97/45209 3 PCTrUS97/09412 adhesion.
SUMM~RY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vacuurn chamber capable s of being used in the formation of layers of surface coating materials that exhibit improved adhesion.
It is another object of the present invention to provide a method of ylc~ hlg such layers of surface coating m~teri~l~
It is a further object of the present invention to provide a substrate which supports a layer 10 of surface adhesion promotion material which, in turn, supports a layer of surface coating material such that the surface coating material exhibits improved adhesion.
In one illustrative embodirnent, the present invention provides a method of depositing a layer of surface coating m~tPri~l The method is carried out in a vacuum chamber and comprises the steps of depositing a layer of surface adhesion promotion material on a surface of a substrate, 15 and depositing a layer of a surface coating m~tPri~l on a surface of the layer of the surface adhesion promotion m~teri~l so that the layer of surface coating material has an adhesion of greater than about 3.75 pounds per inch according to the hesiometry test.
In another illustrative embodiment, the present invention provides an article ofm~nllfiq-~ture. The article comprises a substrate, a layer of surface adhesion promotion m~tPris~l 20 and a layer of a surface coating m~tPri~l The layer of surface adhesion material is supported by the substrate, and the layer of a surface coating m~tPri~l is supported by the layer of surface adhesion promotion ms)tPri~l The surface coating m~t~ri~l has an adhesion of greater than about 3.75 pounds per inch as measured by the hesiometry test.
In a further illustrative embodiment, the present invention provides a vacuum chamber.
2s The chamber comprises a body, a reservoir and plumbing. The body has an orifice with a diameter of less than about 75 mils disposed therein. The reservoir is capable of co,.~ a surface adhesion material. The plumbing is disposed along the perimeter of the orifice of the body to physically connect the plumbing to the body. The plumbing is also physically connected to the reservoir. The plumbing has an orifice disposed therein such that the reservoir is in fluid 30 cot..~ l.ic~tion with the body.
CA 022~6418 1998-11-26 W O 97145209 PCTrUS97/09412 l~TFF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of one embodiment of a vacuum charnber according to the present invention;
Fig. 2 is cross-sectional view of one embodiment of a substrate having disposed thereon a 5 layer of surface adhesion promotion material which has disposed thereon a layer of surface coating material, and Fig. 3 is a schematic representation of one embodiment of an d~ardlus used for performing hesiometry tests according to the present invention.
o DFTAILED DESCRIPTION
In one aspect, the present invention relates to vacuum chambers that can be used to form layers of surface adhesion promotion materials on surfaces such that subsequently deposited surface coating materials exhibit improved adhesion. Fig. 1 depicts one embodiment of a vacuum chamber 10 which includes adhesion promotion deposition C~ll~llnent 11. According I s to the present invention, COlll~ ent 1 1 is designed to allow a relatively even distribution of a sur~ace adhesion promotion material to be disposed onto the surface of a substrate 28, located ~,vithin the body 18 of chamber 10, such that a subsequently deposited layer of a surface coating material e~hibits improved adhesion.
Compartment 11 includes a weldment stub 12 which is welded to vacuum chamber 10 around the perimeter of a hole 14 which is drilled into body 18 of chamber 10. A reservoir 16, cont:~inin~ A174, is in fluid culllll~ ication with body 18 orifice 22 and plumbing 20 which is connected to stub 12. Heating apparatus 26, which is held in place by mounting brackets (not shown~, surrounds reservoir 16. Pump exhaust 31 of vacuurn charnber 10 is disposed such that ~xh~llet 31 is located in a diagonal direction across chamber 10 as far as possible from hole 14.
2s In addition, it is to be noted that reservoir 16 is in a high position relative to exhaust 31.
With this arrangement, a layer of Al 74 is coated onto the surface of substrate 28 as follows. The pressure of vacuum chamber 10 is reduced to its minimllm pressure using standard methods as known to those skilled in the art. The ~ dlLU~ of reservoir 16 is subsequently increased from room temperature to about 190~C by use of heating apparatus 26. At this 3~ temperature, the A174 is evaporated from reservoir 16 in a controlled fashion. The evaporated Al 74 then travels through plumbing 20 to orifice 22 and passes through orifice 22 to enter body 18 of chamber 10. Since the A174 was evaporated at an elevated l~lllp~ldlule, it contains a large CA 022~6418 1998-ll-26 W O 97!45209 PCT~US97/09412 amount of kinetic energy relative to A174 at or below room temperature, so the A174 easily travels within body 18 and is exposed to a substantial portion of the volume of body 18.
Furthermore, because substrate 28 is located the m;1xi~ diagonal distance from hole 14, the density of the evaporated A174 is approximately homogeneous in the region around the surface s of substrate 28. Thus, the A174 which deposits onto the surface of substrate 28 forms a relatively evenly diskibuted layer. It is believed that the formation of a relatively evenly distributed layer of surface adhesion promotion material on the surface of substrate 28 allows a subsequently deposited layer of surface coating material to exhibit improved adhesion. It is to be noted that, during the process of deposition of A174 on the surface of substrate 28, the vaporized 10 A174 may also coat portions of the inner walls of various parts of vacuum chamber 10.
It has been unexpectedly found that vacuum chamber 10 can be pumped down to its minimum pressure without valving off reservoir 16 which contains A174 at room temperature.
In particular, contrary to the conventional wisdom, the vapor pressure of A174 has been found to be low enough that evaporation of A174 does not prevent vacuum chamber 10 from re~ching its 1S minimum p~ ul~ when the A174 is held at room tt;~ Lule. It is believed that orifice 22 is capable of reducing the conductance of A174 from reservoir 16 to body 18 which assists chamber 10 in obtaining its minimllm pressure without complications due to the evaporation of A174.
One common problem with deposition steps in vacuum chambers is associated with the 20 steps of pumping out and subsequently valving off the reservoir and associated plumbing prior to pumping down the body of the vacuum chamber. In many instances, an operator of a vacuum chamber forgets to first pump out the reservoir and associated plumbing prior to valving them off. As a result, when the valve to the reservoir and associated plumbing is opened after ~ulllpillg down the main charnber, the vacuum chamber pressure increases dramatically. This 25 can lead to venting of the vacuum chamber, destruction of vacuurn chamber equipment (e.g., pressure sensitive electronics stored within the vacuum chamber) and/or co~ " .i ~ ion of the substrate surface. This results in a loss of a substantial amount of labor and resources, increasing the costs associated with this process. Therefore, by elimin~tin~ the need of a valve between reservoir 16 and body 18, vacuum chambers in accordance with the present invention can 30 provide a more efficient and less expensive process.
While one particular arrangement of adhesion promotion deposition C<)~ lllllent 11 has been disclosed herein, the present invention is intPn~led to include other arrangements. The CA 022~6418 1998-11-26 W O 97/45209 6 PCTrUS97/09412 particular arrangemcnt of the components of Cul~ ent 1 1 iS limited only in that compartment 11 should be capable of producing a sufficiently evenly distributed layer of surface adhesive material on the sur~ace of substrate 28 such that a subscquently deposited layer of surface coating material exhibits improved adhesion.
s For example, in embo(lim~nt~ in which body 18 of chamber 10 is relatively long and horizontal, reservoir 16 should be located near orifice 33 of pyrolysis chamber 19 (described below).
Reservoir 16 may be any vacuum compatible container that is capable of housing any surface adhesion promotion material. Reservoir 16 should also be chemically inert to the surface 10 adhesion promotion material contained therein at or below the temperature used to deposit the surface adhesion promotion material. One example of such a reservoir is a 100 mL 304 stainless steel tube.
Heating a~a,dLus 26 may be any device that is capable of heating reservoir 16 and the surface adhesion material contained therein in a controlled fashion. Apparatus 26 may also be capable of being mounted to chamber 10 by brackets 24a and 24b, or the like, while supporting reservoir 16. In certain embodiments, ~paldlus 26 may surround reservoir 16. One example of such a heating ~paldlus is a small oven.
Plumbing 20 may be formed from any vacuum compatible material that is capable offluidly connecting reservoir 16 to hole 14. Plumbing 20 should also be chemically inert to A174.
20 In one embodiment, plumbing 20 is formed from a Viton~ O-ring, a 1/8" male coupling and a VCO female connector.
Hole 14 and weldment stub 12 may have any size diameter so long as they are capable of being welded together to form a vacuum tight seal that allows reservoir 16 to be fluidly connected to body 18. Since stub 12 typically is available in predetermined sizes (e.g., 1/8"), it 25 may be advantageous for hole 14 to have a ~ m~ter which corresponds to one these predetermined sizes. In one embodiment, hole 14 and weldment stub 12 each have a diameter of about 118". In certain embodiments, weldment stub 12 may be replaced by an equivalent connecting device, such as a 1/8" Union or a female fractional tube adjuster.
It is believed that orifice 22 may reduce the conductance of vaporized surface adhesion 30 promotion material from reservoir 16 to body 18 such that, subsequent to being heated by a~dldtus 26, the flow of vaporized surface adhesion promotion material into body 18 produces a relatively homogeneous density distribution of vaporized surface adhesion promotion material CA 022~64l8 l998-ll-26 W 097/45209 PCT~US97/09412 throughout portions of body 18. This allows the vaporized surface adhesion promotion material to form a relatively evenly distributed layer on the surface of substrate 28, allowing a subsequently deposited layer of surface coating m~tf~ri~l to exhibit improved adhesion.
Therefore, orifice 22 may be of any size so long as orifice 22 is capable of restricting the flow of S evaporated surface adhesion promotion material from reservoir 16 to body 18 so that the surface adhesion material forms a relatively evenly distributed layer on the surface of substrate 28 and so that a subsequently deposited layer of surface coating material exhibits improved adhesion. It has been found that, in some embodiments, orifice 22 is ineffective if it has a diameter greater than about 100 mils (lmil = 0.001"). Hence, for such embodiments, orifice 22 should have a lo diameter of less than about 75 mils. In one embodiment, orifice 22 has a diameter of about 16 mils.
Vacuum chamber 10 may be any vacuum chamber which is capable of being modified to include C~ .nent 11. In addition, chamber 10 should include surface coating deposition com~ l.ent 13 (Fig. 1). Preferably, body 18 of chamber 10 has a volume of at least about 144 15 cubic inches, more preferably at least about 288 cubic inches and most preferably at least about 432 cubic inches. Such vacuum chambers include, but are not limited to, the following commercially available vacuum chambers, each of which is available from Specialty Coating Systems, Inc, Clear Lake, W~: model 1050 (part no. 2169800), model 1030 (part no. 216802);
model 2090 (part no. 2169803); model 2010 (part no. 2169804); and model 2060 (part no.
20 BM02616).
As shown in Fig. 1, surface coating deposition compartment 13, which is a~n)pliate for use with the parylene family of surface coating materials, should include vaporization chamber 15, pyrolysis chamber 17 and post-pyrolis chamber 19. Vaporization chamber 15 evaporates the parylene dimer, pyrolysis chamber 17 cleaves the parylene dimer to form a gas including 25 parylene monomer, and post-pyrolysis chamber includes at least one cooled baffle to remove any parylene dimer from the gas. Such deposition cOlllp~ lments are disclosed in commonly assigned U.S. Patent Serial No. 08/549,087 which is herein incorporated by reference. While certain embodiments of COl~ l Llllent 13 have been disclosed herein, it is to be understood that conlpal~ll,ent 13 is not limited by these embo-liment~ ~ompartment 13 may include any 30 combination of devices that are capable of acting in unison to deposit a layer of surface coating mslt~ri~l onto a layer of surface adhesion promotion material disposed on the surface of substrate 28. Such co~ ~Lll,ents are known to those skilled in the art and are inten~led to be within the CA 022~6418 1998-ll-26 W O 97t~5209 8 PCTrUS97/~9412 scope of the present invention.
Methods of depositing a layer of surface coating m~t~.ri~l using compartment 13 include the steps of vaporizing the parylene dimer, pyrolizing the parylene to form a gas including monomers of the parylene, passing the gas through at least one cooled baffle to remove any s parylene dimer in the gas, and depositing the monomer of parylene on the layer of the surface adhesion promotion material which is disposed on the surface of substrate 28. Such methods are described in, for example, U.S. Patent Application Serial No. 08/549,087. Other methods of depositing a layer of surface coating material are known to those skilled in the art and are int~n~le-l to be within the scope of the present invention.
Fig. 2 depicts a cross-sectional view of one embodiment of substrate 28 having a surface 30 on which a layer 32 of surface adhesion promotion material is deposited. A layer 34 of surface coating material is disposed on layer 32. Surface 30 may have any area so long as layer 32 can be deposited thereon such that subsequently deposited layer 34 exhibits improved adhesion. While ~ig. 1 depicts chamber 10 having one substrate 28 disposed therein, it is to be 15 understood that chamber 10 may have a plurality of subskates disposed therein. In certain embodiments in which a plurality of substrates are disposed within chamber 10, the total surface area of the substrates is preferably at least about 100 square inches.
According to the present invention, substrate 28 may be any object or body having surface 30 onto which a surface adhesion promotion material may be deposited by at least one of 20 the methods of the present invention. Substrate 28 may be formed from organic materials or inorganic materials including, for example, polymeric materials, semiconductor materials, metallic materials, oxides of metallic mzltPri~l~ and the like. Such organic m~tfxi~l~ and inorganic materials include, but are not limited to, all.,--i.-l.,.~, iron, steel, molybdenum, al..,.li..l.lll oxide, titanium oxide, lead oxide, copper oxide, iron oxide, beryllium oxide, 25 m~n~n~se oxide, tlln~cten oxide, tantalum oxide, v:~n~ m oxide, silicones, natural rubbers, plastic composites, cellulosic m5lt~ri~l~, epoxy-co~ g compounds, thermosetting compounds, thermoplastic compounds, silicon oxide (e.g., sand, fly ash, hydrated silica, silica, quartz, aerogel, xerogel, fumed silica) and the like. Substrate 28 may also be formed from a vacuum compatible liqu;d. By "vacuum compatible" it is herein meant to refer to a material that 30 has a vapor pressure at room temperature such that the minimllm ])L~S~ c; to which a vacuum chamber can be pumped is independent of the presence of the vacuum compatible material. One exarnple of such a vacuum compatible liquid is A174. Other such vacuum compatible materials CA 022~6418 1998-ll-26 W O 97/45209 9 PCT~US97/09412 will be a~p~elll to those skilled in the art and are intended to be within the scope of the present mventlon.
In certain embodiments, substrate 28 may be a printed circuit board, a silicon wafer, paper, a key pad, a catheter, a pacemaker cover, a subcutaneous probe, a bird feather, a silicone , 5 O-ring or the like.
Layer 32 of surface adhesion promotion material may be formed from any vacuum compatible material that is capable of ~im~ n~ously bonding to surface 30 and layer 34 such that layer 34 has an adhesion of greater than about 3.75 pounds per inch (Ibs/in) as measured according to the hesiometry test, more preferably at least about 5 lbs/in and most preferably at lo least about 8 lbs/in.
As used herein, the term "hesiometry test" refers to a test which was developed by W. K.
Asbeck, Paint and Varn~sh Prod. p. 23,1970. Fig.3 represents the setup used in the hesiometry test. Substrate 30 is placed on a motorized stage 40 which moves in a direction indicated by the arrow. As stage 40 moves, a knife-like device 42 cuts ch~nnel~ in layers 32/ 34. Device 42 is lS pushed through the interface between substrate 28 and layers 32/34, and the horizontal force (Fh)is measured by a transducer 44. Substrate 28 is returned to its starting point and run again so that the contribution due to the frictional force between device 42 and surface 30 can be measured. The difference between the horizontal force and the frictional force is equal to the adhesion of layer 34.
Although layer 32 of surface adhesion promotion material may be formed from any m~eri~l having the properties discussed above, layer 32 is preferably formed from an organosilane, more preferably from an alkoxysilane, and most preferably from A174 (i.e., gamma-methacryloxy,~l~,pyltrimethoxysilane).
In some embo~limenl~, layer 32 is formed from a multi-layer of molecules of surface 25 adhesion promotion m~t~ri~l In these embodiments, some molecules of surface adhesion promotion material bond with surface 30 while other molecules of surface adhesion promotion m~t~ri~l do not bond with surface 30. A "bond" as used herein refers to any combination of chemical bonding, physical entanglement or physical bonding, such as hydrogen bonding or van der Waals bonding.
For emborliment~ in which layer 32 is formed from a multi-layer of molecules of surface adhesion promotion material, layer 32 should have a thickn~,cs of at least about 20 ~ as measured CA 022~6418 1998-11-26 W O 97/45209 10 PCT~US97/09412 using a ~ua~tz crystal thickness monitor or an equivalent device. It is to bc noted that if layer 32 is less than about 20 ~ thick, layer 34 may not have sufficient adhesion.
In some embo~1iment~, molecules of surface adhesion promotion materials have a polar end and a nonpolar end. For example, Al 74 has a polar end (trimethoxy) and a nonpolar end s (methacryloxy). While it is not fully understood, it is believed that, when such surface adhesion promotion materials are used with surfaces that are more polar than the nonpolar end of the molecules of the surface adhesion material, the polar ends of the molecules of the surface adhesion mslt~ri~l bond to the surface and the nonpolar ends of the molecules of the surface adhesion material are directed away from the surface. With this configuration, the molecules of I o the surface coating material are exposed to the nonpolar ends of the molecules of the surface adhesion mslt~ri~l rather than the c()~ ,aldtively polar surface. If the surface molecules of the surface coating material are nonpolar relative to the surface, the surface molecules of the surface coating material may bond more readily to the nonpolar end of the molecules of the surface adhesion material than the relatively polar surface.
Layer 34 of surface coating material may be formed ~om any mslt~ri~l th~t is capable of bonding to layer 32 and which is capable of forming a layer of material that is chemically inert relative to surface 30. Such m~t( ri~l~ are known to those skilled in the art and include, for exarnple, poly-p-xylylene materials. An illustrative and nonlimiting list of such poly-p-xylylenes includes parylene D, parylene N, parylene C and octafluoro-~2,2] paracyclophane such as disclosed in commonly assigned U.S. Patent Application Serial No. 08/544,831 which is hereby incorporated by reference.
In certain embo~1iment~, layer 34 may have dirr~ l physical l~lop~lies than surface 30.
For example, layer 34 may have a different rollghness, electrical conductivity and/or therrnal conductivity than surface 30.
2s The following examples are int~n~lecl for illustrative purposes and is not to be construed as limiting.
F.x~n~le 1 A substrate without a layer of surface coating m~t~ri~l was deposited on a substrate as follows. A borosilicate substrate was cleaned by hand washing with a 2% solution of Microsoap~ in water. The substrate was rinsed with de-ionized water and placed in an autoclave.
The substrate was heated in the autoclave at 250~F for about one hour in the presence of de-CA 022~6418 1998-ll-26 W O 97/45209 ~ PCTrUS97/09412 ionized water. The substrate was removed from the autoclave, and any rem~inin~ liquid was blown off with ul~1~u1~ nitrogen gas. The substrate was then vacuum baked at a temperature of about 50~C at a pressure of less than 100 mTorr.
The cleaned substrate was then coated with parylene C by f1rst vaporizing the solid dimer of parylene C. The methylene-methylene bonds of the parylene were then cleaved in the pyrolosis chamber at a temperature of about 680"C to yield monomers of the parylene C. The monomer was subsequently deposited onto the layer of A174. Upon deposition, the monomers of A174 polymerized. The coated substrate was removed from the vacuum chatnber stressed by pl~ menf in an autoclave for a time period of about one hour at a temperature of about 250~F in 1 o the presence of de-ionized water.
The adhesion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average adhesion was measured to be about 0.25 Ibs/in according to the hesiometry test.
Ex~mple 2 A substrate having a layer of surface adhesion promotion m~t( ri~l deposited in sllhst~nti~l accordance with the method disclosed in U.S. Patent No. 3,6~0,216 and a further layer of a surface coating m~t~.ri~l was prepared as follows. A borosilicate substrate as described in Exarnple 1 was cleaned according to the method disclosed in Example 1. A layer of A174 was applied to the surface of the borosilicate substrate by dipping the in a solution of 0.5% A174, 49.75% de-ionized water and 49.75% isop1vp~ulol. This dipping procedure was carried out for about 15 min~ltes. The substrate was then dried for about 15 minutes and subsequently rinsed with neat iso~ ol. The substrate was next air dried for about one half hour.
2s The layer of A174 provided by the above method was coated with parylene C~ and stressed as described in Example 1. The a&esion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average adhesion was measured by the hesiometry test to be about 2.25 Ibs/in.
CA 022~6418 1998-ll-26 W O 97145209 -12- PCT~US97/09412 Fx~rr~le 3 A substrate with a layer of surface adhesion promotion material was prepared as follows.
A borosilicate substrate as described in Example 1 was cleaned according to the method disclosed in Example 1. A borosilicate substrate as described in Example 1 was cleaned s according to the method of Example 1. The substrate was then placed in a vacuum chamber, and a layer of Al 74 was applied to the surface of the ~ub~Lldte under vacuum conditions. The coated subskate was then removed from this vacuum chamber and transferred to a second vacuum chamber in accordance with methods described herein (i.e., the coated substrate was exposed to atmospheric conditions prior to the deposition of the surface coating material).0 The layer of Al 74 was then coated with parylene C and stressed as described in Example 1. It is to be noted that the coated substrate was exposed to a substantial amount of dynarnic pumping in the second vacuum chamber prior to the deposition of the surface coating material.
The adhesion of the coating of parylene C material was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points.
15 The average adhesion was measured by the hesiometry test to be about 3.75 Ibs/in.
Fx~ml?le 4 A borosilicate ~ub~ as described in Example 1 was cleaned according to the method of Example 1. The substrate was then placed in a model 1050 parylene generation vacuum 20 chamber (part no. 2169800, Specialty Coatings Systems, Inc., Clear Lake, WI) which was modified as shown in Fig. 1. The ~l~s~ule of the chamber was reduced to about 50 m;lliTorr.
About 2.5 mL of Al 74 was vaporized at a t~ d~ of about 190 ~C, and the thickness of the coating of Al 74 was monitored using a quartz crystal thickness monitor (Model No. TM 100, available from Maxtek). The layer of Al 74 was then coated with parylene C and stressed as 25 described in Example 1. The layer of A174 was about 227 ~ and the layer of parylene C was from about 4000 A to about 5000 ~. Adhesion of the coating of parylene C m~tt~n~l was then measured using the hesiometer test described above. This experiment was repeated four times to achieve a total of five data points. The average a&esion was measured to be about 8 lbs/in according to the hesiometry test.
As indicated by Example 1, when a layer of Al74 is not applied to the borosilicate surface prior to the deposition of the parylene material, the parylene material has the poorest CA 022~6418 1998-11-26 W O 97/45209 -13- PCT~US97109412 adhesion. Furthermore, when a layer of A174 is applied from solution (Fx~mple 2), the subsequently deposited layer of parylene material exhibits poor adhesion. In addition, when the A174 coated borosilicate substrate is exposed to atmospheric conditions prior to the deposition of the parylene material (Example 3), the layer of parylene material exhibits inferior adhesion.
~, 5 However, when the process of the present invention is used to apply the layers of Al 74 and parylene material to the borosilicate substrate (Example 4), the layer of parylene material exhibits better adhesion than when the methods of Fxs~mples 1-3 are used.
Having thus described certain embo~liment~ of the present invention, various improvements, modifications and alterations will be obvious to those skilled in the art. Such lo improvements, modifications and alterations are jn~nded to be within the spirit and scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended as limitin~. The invention is limited only as defined in the following the claims and equivalents thereto.
What is claimed is:
Claims (20)
1. A method of depositing a layer of surface coating material, the method comprising the steps of:
depositing, within a vacuum chamber, a layer of surface adhesion promotion material on a surface of a substrate; and depositing, within the vacuum chamber, a layer of a surface coating material on a surface of the layer of the surface adhesion promotion material so that the layer of surface coating material has an adhesion of greater than about 3.75 pounds per inch according to a hesiometry test.
depositing, within a vacuum chamber, a layer of surface adhesion promotion material on a surface of a substrate; and depositing, within the vacuum chamber, a layer of a surface coating material on a surface of the layer of the surface adhesion promotion material so that the layer of surface coating material has an adhesion of greater than about 3.75 pounds per inch according to a hesiometry test.
2. The method according to claim 1, wherein the step depositing a layer of surface coating material includes depositing the layer of surface adhesion promotion material so that the layer of surface coating material has an adhesion of at least about 5 pounds per inch as measured using the hesiometry test.
3. The method according to claim 1, wherein the step of depositing a layer of surface adhesion promotion material includes reducing the pressure of the vacuum chamber while exposing the vacuum chamber to a reservoir of the surface adhesion promotion material
4. The method according to claim l, wherein the step of depositing a layer of surface adhesion promotion material includes heating a reservoir of the surface adhesion promotion material to a temperature above room temperature.
5. The method according to claim 1, wherein the step of depositing a layer of surface adhesion promotion material includes depositing a layer of surface adhesion promotion material having a thickness of at least about 20 A.
6. The method according to claim 1, wherein the step of depositing a layer of surface adhesion promotion material includes passing the surface adhesion promotion material through an orifice having a diameter of less than about 75 mils.
7. The method according to claim 1, wherein the step of depositing a layer of surface adhesion promotion material on a surface of a substrate includes depositing a layer of surface adhesion promotion material on a surface of each of a plurality of substrates, a total surface area of the surface of each of the plurality of substrates being at least about 100 square inches.
8. An article of manufacture, comprising:
a substrate;
a layer of surface adhesion promotion material supported by the substrate; and a layer of a surface coating material supported by the layer of surface adhesion promotion material, the surface coating material having an adhesion of greater than about 3.75 pounds per inch as measured by a hesiometry test.
a substrate;
a layer of surface adhesion promotion material supported by the substrate; and a layer of a surface coating material supported by the layer of surface adhesion promotion material, the surface coating material having an adhesion of greater than about 3.75 pounds per inch as measured by a hesiometry test.
9. The article according to claim 8, wherein the surface coating material has an adhesion of at least about S pounds per inch as measured by the hesiometry test.
10. The article according to claim 8, wherein the surface coating material has an adhesion of at least about 8 pounds per inch as measured by the hesiometry test.
11. The article according to claim 8, wherein the surface adhesion promotion material is formed from gamma-methacryloxypropyltrimethoxysilane.
12. The article according to claim 8, wherein the surface adhesion promotion material has a thickness of at least about 20.ANG..
13. A vacuum chamber, comprising:
a body having an orifice disposed therein, the orifice of the body having a perimeter;
a reservoir capable of containing a surface adhesion material; and plumbing disposed along the perimeter of the orifice of the body to physically connect the plumbing to the body, the plumbing being physically connected to the reservoir, the plumbing having an orifice disposed therein such that the reservoir is in fluid communication with the body.
a body having an orifice disposed therein, the orifice of the body having a perimeter;
a reservoir capable of containing a surface adhesion material; and plumbing disposed along the perimeter of the orifice of the body to physically connect the plumbing to the body, the plumbing being physically connected to the reservoir, the plumbing having an orifice disposed therein such that the reservoir is in fluid communication with the body.
14. The vacuum chamber according to claim 13, further comprising a heating apparatus physically connected to the body, the heating apparatus disposed adjacent the reservoir so that the heating apparatus can heat the reservoir.
15. The vacuum chamber according to claim 13, wherein the heating apparatus is capable of heating the reservoir to a temperature of at least about 190°C.
16. The vacuum chamber according to claim 13, wherein the orifice of the plumbing has a diameter of less than about 75 mils.
17. The vacuum chamber according to claim 13, wherein the body has a volume of at least about 144 cubic inches.
18. The vacuum chamber according to claim 13, wherein the body has a volume of at least about 288 cubic inches.
19. The vacuum chamber according to claim 13, wherein the body has a volume of at least about 432 cubic inches.
20. The vacuum chamber according to claim 13, further comprising surface coatingdeposition compartment.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US65782096A | 1996-05-31 | 1996-05-31 | |
| US08/657,820 | 1996-05-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2256418A1 true CA2256418A1 (en) | 1997-12-04 |
Family
ID=24638775
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2256418 Abandoned CA2256418A1 (en) | 1996-05-31 | 1997-05-29 | Chambers for promoting surface adhesion under vacuum and methods of using same |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0910484A2 (en) |
| JP (1) | JP2000511971A (en) |
| CA (1) | CA2256418A1 (en) |
| WO (1) | WO1997045209A2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2806076B1 (en) * | 2000-03-08 | 2002-09-20 | Saint Gobain Vitrage | TRANSPARENT SUBSTRATE COATED WITH A POLYMER LAYER |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3900600A (en) * | 1973-06-29 | 1975-08-19 | Ibm | Paraxylylene-silane dielectric films |
| CA1119056A (en) * | 1976-08-23 | 1982-03-02 | Dennis M. Mahoney | Adhesion of a vapor deposited polymer to a substrate by pre-treatment of the substrate with vaporous coupling agents |
| US5201956A (en) * | 1992-06-26 | 1993-04-13 | Specialty Coating Systems Inc. | Cellular tumble coater |
| US5424097A (en) * | 1993-09-30 | 1995-06-13 | Specialty Coating Systems, Inc. | Continuous vapor deposition apparatus |
-
1997
- 1997-05-29 EP EP97927897A patent/EP0910484A2/en not_active Withdrawn
- 1997-05-29 CA CA 2256418 patent/CA2256418A1/en not_active Abandoned
- 1997-05-29 WO PCT/US1997/009412 patent/WO1997045209A2/en not_active Application Discontinuation
- 1997-05-29 JP JP09543027A patent/JP2000511971A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0910484A2 (en) | 1999-04-28 |
| WO1997045209A3 (en) | 1998-02-12 |
| WO1997045209A2 (en) | 1997-12-04 |
| JP2000511971A (en) | 2000-09-12 |
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