CA1119482A - Method for applying a photo polymer to surfaces - Google Patents
Method for applying a photo polymer to surfacesInfo
- Publication number
- CA1119482A CA1119482A CA000319016A CA319016A CA1119482A CA 1119482 A CA1119482 A CA 1119482A CA 000319016 A CA000319016 A CA 000319016A CA 319016 A CA319016 A CA 319016A CA 1119482 A CA1119482 A CA 1119482A
- Authority
- CA
- Canada
- Prior art keywords
- sponge
- photo polymer
- resist
- solvent
- photo
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Application Of Or Painting With Fluid Materials (AREA)
Abstract
Abstract of the Disclosure A method for applying a liquid photo polymer to a surface such that the photo polymer is uniform and holiday-free, the method comprising obtaining a plastic sponge and impregnating the plastic sponge with a liquid photo polymer comprising a solvent which slowly reacts with the plastic from which the sponge is formed. Thereafter, the sponge is brushed and/or drawn across the surface to deposit the photo polymer thereon, the application of the photo polymer being accomplished before the solvent in the photo polymer sub-stantially disintegrates the sponge.
Description
g~
METHOD FOR APPLYIN& A
PHOTO POLYMER TO SURFAC~S
~=l~icat:iOn The present invention relates to applying a photo polymer to a surface and more particularly to a novel method for applying a uniform, holiday-f:ree photo polymer layer on surfaces of both smooth and/or irregular config-uration.
The use of photo polymers in the photo fabricating industry is extremely well-known for such valuable uses as production of printed circuits, photo etching, photoen-graving and chemical milling and machining. These important processes have historically included a number of conven-tional steps:
A surface to be etched or milled is first coated with a light-sensitive photo polymer which, when cured, becomes resistant to acids, alkalies or both. Hence, the first photo polymer is commonly called a "resist". Conventionally, a mask is placed over the resist-coated surface so as to leave only selected portions of the resist exposed ancl unmasked. Depending upon the type of resist used, the light impinging upon the unmasked areas either hardens the resists or degrades the resist so that when the resist-coated part of ~he surface is subsequently washed in a developer, part of the resist is removed leaving an image defined by the mask on the surface.
The key in producing high quality work of this type is to apply liquid resists uniformly and free from dust, dirt and voids or pin holes, commonly referred to as holidays.
~.
~ 8 ~
The difficul~y of properly applying liquid resist is well-know~ in the indu9 try and numerous techniques have been tried. One somewhat effective prior art me~hod includes completely immersing a surface in liquid -resist and slowly removing the surface from the liquid to improve the uni-formity of resist thickness. The dipping method has, however, proved to be extremely slow and cumbersome. This is particularly true where the surface is very large or where placemen~ of resist on all parts of the surface is undeslrable.
In the face o:E serious problems encountered in applying liquid resist, at least two major suppliers of resist have abandoned the liquid resist approach and have developed solid film resists which are laminated to the surface.
While solid film resists are more expensive than liquid resist, they have gained a strong foothold in the industry because many ~eel that they can be more reliably applied than liquid resists.
I~ would therefore be a substantial contribution to the industry to provide a technique of applying liquid resis~ so as to be uniform and holiday-free The invention deEined herein provides for a ~iniform holiday-free application of liquid resist to regular and irregular surfaces by impregnatin~ a plastic sponge material with a liquid resist comprising a solvent which tends to slowly react with the fabric of the sponge. The sponge thus impregnated has been found to uniquely apply a superior liquid resist coating upon the surface.
~ 9 ~
It is, therefore, a prlmary object of the present invention to provide an improved method for applying a liquid resist.
This and other objects and features of the present invention will become more fully apparent from -the following descrip~ion and appended claims taken in conjunction with the accompanying drawing.
The drawing is a schematic flow diagram illustrating principal steps of a preferred embodiment of the invention.
According to the presently preferred embodiment of the invention, a desired liquid photo polymer resist 12 is selected for application to a surface 14. Any suitably liquid photo resist polymer such as Eastman Kodak KPR, KMR, Dynachem GMR 5000 or the like may be used. All of the well known photo polymer resists comprise a solvent which volat-ilizes in the atmosphere to cure the resist.
Next, an applicator 16 is selected. Preferably, the applicator 16 is fabricated from a cellular sponge material pre~erably made o~ synthetic plastic. The synthetic plas-tics are preferred because they are more easily affected bythe common solvents in conventional resists. According to the present invention, it has been found surprisingly effective to use a sponge applicator 16 which slowly reacts with the solvent of the photo resist. Initially, the sponge material is impregnated with the photo resist whereupon the solvent in the resist is permitted to react at least with the exterior of the applicator. Care is taken, however, to insure that the applicator is not permitted to be exposed ~ 3~
directly to the sol-vent or so long a time that the sponge fabric disintegrates It has been found that for most conventional plastic sponges the applicator 16 will be effective to apply resist properly within less than one to five minutes after impregnation with resist, ~epending upon the particular solvent in the resist. Most sponge appLi-cators, depending upon si~e, retain overall integrity for several hours a~ter impregnation.
~fter the sponge applicator 16 has been impregnated with resist, and sufficient interaction between the resist and the applicator has taken place to permit holiday-free application, the sponge applicator is brushed lightly across the surface 14 in continuous strokes. After completing one stro~e, another stroke is made with slight overlap of the first as illustrated in the figure. Sequential application is continued until all the desired portions of the surface 14 are covered with resist.
The solvent-softened resist-impregnated sponge appli-cator was found surprisingly effecti~e in delivering a uniform holiday-free resist coat. The solvent in the photo resist causes the sponge applicator 16 to become extremely soft so that the sponge conforms to the surface 14 and adequately appl~es resist even to surface irregularities, small ~its and scratches in the surface. The applicator 16 has been ~ound con~enient in applying photo resist to surfaces ha~ing unusual configurations such as curved suxfa~es, and inside surfaces. ~loreover, extremely large objects which can be dipped or roller coated only with specialized e~uipment can be easily coated with the appli-cator 16.
In an attempt to determine why a paint brush would no~
provide the same satisfactory resul~s as obtained with applicator 16, it was concluded that the bristles of -the brush must (a) be made infinitely so:Et or ~b) be made to melt or dissolve into the resist ~luid. Clearly, there are no paint brushes with infinitely soft bristles and if the bristles melted they would contaminate the resist. On the other hand, it was discovered that certain plastic sponges useful in the practice of this invention were swelled by the solvents in the resist system but were not lmmediately dissolved thereby. This swelling of the plastic sponge causes the plastic sponge to become extremely soft and hold a substantial quantity of resist thereby providing a uniform, dust and holiday-free resist coating.
In addition, the softened plastic sponge or applicator 16 readily conforms to the various surface contours as well as covering minor surface irregularities such as small pits, scratches and the like.
~ fter application of the surface 14 has been complete~, the photo resist is preferably washed from the applicator to increase the life of the applicator. ~s mentioned above, if the photo ~esist is allowed to remain in khe sponge for an extended length of time, depending upon the fabric of the sponge and the particular solvent in the resist, the sponge will disintegrate. If the sponge is washed after each use, it may ~e used se~eral times before replacement is required.
The following non-limiting examples are representative of the method.
Example 1 A plas-tic ~oam sponge was dipped into a pan of Eastman-Kodak resist identified as KPR-3. The sponge was found to become fully impregnated in several seconds. The impreg-nated sponge was then lightly drawn across a printed circuit laminate measuring 36 ~ 24 i.nches. The sponge delivered a coat of resist four inches wide across the laminate and, lQ after completing one stroke, another stroke was made slightly overlapping the previously coated area. This sequence was repea~ed until the complete laminate was covered with resist. The slight overlap was ~ound to equalize homo~
genously so that the resist coating was substan-tially uniform and remarkably holiday-~ree.
Example 2 An instrument panel measuring 2 inches by 3 inches to be manufactured by the photo fabrication method was coated with resist by dipping a sponge into Dynachem resist 315 ; 20 and dragged lightly across the surface of the panel. A
uniform highly desirable coating of resist resulted.
E a ~
Cylinders having a four inch diameter were coated with resist so that an emblem could be photoengraved onto the exterior sur~ace. A plastic foam sponge impregnated with Dynachem CMR 5~00 was drawn lightly across the surface to be : photoeng~a~ed. A uniform substantially holiday-free resist layer resulted.
Example 4 Chemically milled screens from stainless steel were prepared by placing a first resist coat on one side of a stainless steel sheet as set forth in the foregoing example.
After the resist had dried, the sheet was turned over and the other side coated in a like manner. Parts chemically machined from this double side resist coated stainless steel were uniform and of surprisingly high quality.
The invention may be embodied in other specific forms without departing from its spirit or essential character-istics. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description.
All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
What is claimed and desired to be secured by United States Le~ters Patent is:
METHOD FOR APPLYIN& A
PHOTO POLYMER TO SURFAC~S
~=l~icat:iOn The present invention relates to applying a photo polymer to a surface and more particularly to a novel method for applying a uniform, holiday-f:ree photo polymer layer on surfaces of both smooth and/or irregular config-uration.
The use of photo polymers in the photo fabricating industry is extremely well-known for such valuable uses as production of printed circuits, photo etching, photoen-graving and chemical milling and machining. These important processes have historically included a number of conven-tional steps:
A surface to be etched or milled is first coated with a light-sensitive photo polymer which, when cured, becomes resistant to acids, alkalies or both. Hence, the first photo polymer is commonly called a "resist". Conventionally, a mask is placed over the resist-coated surface so as to leave only selected portions of the resist exposed ancl unmasked. Depending upon the type of resist used, the light impinging upon the unmasked areas either hardens the resists or degrades the resist so that when the resist-coated part of ~he surface is subsequently washed in a developer, part of the resist is removed leaving an image defined by the mask on the surface.
The key in producing high quality work of this type is to apply liquid resists uniformly and free from dust, dirt and voids or pin holes, commonly referred to as holidays.
~.
~ 8 ~
The difficul~y of properly applying liquid resist is well-know~ in the indu9 try and numerous techniques have been tried. One somewhat effective prior art me~hod includes completely immersing a surface in liquid -resist and slowly removing the surface from the liquid to improve the uni-formity of resist thickness. The dipping method has, however, proved to be extremely slow and cumbersome. This is particularly true where the surface is very large or where placemen~ of resist on all parts of the surface is undeslrable.
In the face o:E serious problems encountered in applying liquid resist, at least two major suppliers of resist have abandoned the liquid resist approach and have developed solid film resists which are laminated to the surface.
While solid film resists are more expensive than liquid resist, they have gained a strong foothold in the industry because many ~eel that they can be more reliably applied than liquid resists.
I~ would therefore be a substantial contribution to the industry to provide a technique of applying liquid resis~ so as to be uniform and holiday-free The invention deEined herein provides for a ~iniform holiday-free application of liquid resist to regular and irregular surfaces by impregnatin~ a plastic sponge material with a liquid resist comprising a solvent which tends to slowly react with the fabric of the sponge. The sponge thus impregnated has been found to uniquely apply a superior liquid resist coating upon the surface.
~ 9 ~
It is, therefore, a prlmary object of the present invention to provide an improved method for applying a liquid resist.
This and other objects and features of the present invention will become more fully apparent from -the following descrip~ion and appended claims taken in conjunction with the accompanying drawing.
The drawing is a schematic flow diagram illustrating principal steps of a preferred embodiment of the invention.
According to the presently preferred embodiment of the invention, a desired liquid photo polymer resist 12 is selected for application to a surface 14. Any suitably liquid photo resist polymer such as Eastman Kodak KPR, KMR, Dynachem GMR 5000 or the like may be used. All of the well known photo polymer resists comprise a solvent which volat-ilizes in the atmosphere to cure the resist.
Next, an applicator 16 is selected. Preferably, the applicator 16 is fabricated from a cellular sponge material pre~erably made o~ synthetic plastic. The synthetic plas-tics are preferred because they are more easily affected bythe common solvents in conventional resists. According to the present invention, it has been found surprisingly effective to use a sponge applicator 16 which slowly reacts with the solvent of the photo resist. Initially, the sponge material is impregnated with the photo resist whereupon the solvent in the resist is permitted to react at least with the exterior of the applicator. Care is taken, however, to insure that the applicator is not permitted to be exposed ~ 3~
directly to the sol-vent or so long a time that the sponge fabric disintegrates It has been found that for most conventional plastic sponges the applicator 16 will be effective to apply resist properly within less than one to five minutes after impregnation with resist, ~epending upon the particular solvent in the resist. Most sponge appLi-cators, depending upon si~e, retain overall integrity for several hours a~ter impregnation.
~fter the sponge applicator 16 has been impregnated with resist, and sufficient interaction between the resist and the applicator has taken place to permit holiday-free application, the sponge applicator is brushed lightly across the surface 14 in continuous strokes. After completing one stro~e, another stroke is made with slight overlap of the first as illustrated in the figure. Sequential application is continued until all the desired portions of the surface 14 are covered with resist.
The solvent-softened resist-impregnated sponge appli-cator was found surprisingly effecti~e in delivering a uniform holiday-free resist coat. The solvent in the photo resist causes the sponge applicator 16 to become extremely soft so that the sponge conforms to the surface 14 and adequately appl~es resist even to surface irregularities, small ~its and scratches in the surface. The applicator 16 has been ~ound con~enient in applying photo resist to surfaces ha~ing unusual configurations such as curved suxfa~es, and inside surfaces. ~loreover, extremely large objects which can be dipped or roller coated only with specialized e~uipment can be easily coated with the appli-cator 16.
In an attempt to determine why a paint brush would no~
provide the same satisfactory resul~s as obtained with applicator 16, it was concluded that the bristles of -the brush must (a) be made infinitely so:Et or ~b) be made to melt or dissolve into the resist ~luid. Clearly, there are no paint brushes with infinitely soft bristles and if the bristles melted they would contaminate the resist. On the other hand, it was discovered that certain plastic sponges useful in the practice of this invention were swelled by the solvents in the resist system but were not lmmediately dissolved thereby. This swelling of the plastic sponge causes the plastic sponge to become extremely soft and hold a substantial quantity of resist thereby providing a uniform, dust and holiday-free resist coating.
In addition, the softened plastic sponge or applicator 16 readily conforms to the various surface contours as well as covering minor surface irregularities such as small pits, scratches and the like.
~ fter application of the surface 14 has been complete~, the photo resist is preferably washed from the applicator to increase the life of the applicator. ~s mentioned above, if the photo ~esist is allowed to remain in khe sponge for an extended length of time, depending upon the fabric of the sponge and the particular solvent in the resist, the sponge will disintegrate. If the sponge is washed after each use, it may ~e used se~eral times before replacement is required.
The following non-limiting examples are representative of the method.
Example 1 A plas-tic ~oam sponge was dipped into a pan of Eastman-Kodak resist identified as KPR-3. The sponge was found to become fully impregnated in several seconds. The impreg-nated sponge was then lightly drawn across a printed circuit laminate measuring 36 ~ 24 i.nches. The sponge delivered a coat of resist four inches wide across the laminate and, lQ after completing one stroke, another stroke was made slightly overlapping the previously coated area. This sequence was repea~ed until the complete laminate was covered with resist. The slight overlap was ~ound to equalize homo~
genously so that the resist coating was substan-tially uniform and remarkably holiday-~ree.
Example 2 An instrument panel measuring 2 inches by 3 inches to be manufactured by the photo fabrication method was coated with resist by dipping a sponge into Dynachem resist 315 ; 20 and dragged lightly across the surface of the panel. A
uniform highly desirable coating of resist resulted.
E a ~
Cylinders having a four inch diameter were coated with resist so that an emblem could be photoengraved onto the exterior sur~ace. A plastic foam sponge impregnated with Dynachem CMR 5~00 was drawn lightly across the surface to be : photoeng~a~ed. A uniform substantially holiday-free resist layer resulted.
Example 4 Chemically milled screens from stainless steel were prepared by placing a first resist coat on one side of a stainless steel sheet as set forth in the foregoing example.
After the resist had dried, the sheet was turned over and the other side coated in a like manner. Parts chemically machined from this double side resist coated stainless steel were uniform and of surprisingly high quality.
The invention may be embodied in other specific forms without departing from its spirit or essential character-istics. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description.
All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
What is claimed and desired to be secured by United States Le~ters Patent is:
Claims (3)
1. In a method of distributing a photo polymer over a surface, the steps of absorbing liquid photo polymer into a plastic sponge; allowing solvent in the photo polymer to chemically react with and at least partially soften at least the exterior of the sponge; and drawing at least a portion of the photo polymer impregnated sponge across the surface.
2. A method as defined in claim 1 wherein said allowing step comprises contacting the solvent in the photo polymer with the sponge for a time increment which is long enough to effect slight dissolution of peripheral portions of the sponge but insufficient to cause the sponge to disintegrate.
3. ~ method of applying a photo polymer to a surface comprising the steps of:
obtaining a liquid photo polymer comprising a solvent;
obtaining a sponge applicator, the sponge com-prising a synthetic open cellular material which is subject to slow dissolution by the solvent of the photo polymer;
absorbing the liquid photo polymer into the sponge applicator;
softening at least the exterior of the sponge with the solvent; and applying the liquid photo polymer to the surface by drawing the sponge applicator across the surface before the solvent causes the sponge to substantially disintegrate.
obtaining a liquid photo polymer comprising a solvent;
obtaining a sponge applicator, the sponge com-prising a synthetic open cellular material which is subject to slow dissolution by the solvent of the photo polymer;
absorbing the liquid photo polymer into the sponge applicator;
softening at least the exterior of the sponge with the solvent; and applying the liquid photo polymer to the surface by drawing the sponge applicator across the surface before the solvent causes the sponge to substantially disintegrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000319016A CA1119482A (en) | 1979-01-03 | 1979-01-03 | Method for applying a photo polymer to surfaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000319016A CA1119482A (en) | 1979-01-03 | 1979-01-03 | Method for applying a photo polymer to surfaces |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119482A true CA1119482A (en) | 1982-03-09 |
Family
ID=4113230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000319016A Expired CA1119482A (en) | 1979-01-03 | 1979-01-03 | Method for applying a photo polymer to surfaces |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119482A (en) |
-
1979
- 1979-01-03 CA CA000319016A patent/CA1119482A/en not_active Expired
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| MKEX | Expiry |