A method for applying photographic resists to otherwise incompatible substrates, such as a baking enamel paint surface, is described wherein the uncured enamel paint surface is coated with a non-curing lacquer which is, in turn, coated with a partially cured lacquer. The non-curing lacquer adheres to the enamel and a photo resist material satisfactorily adheres to the partially cured lacquer. Once normal photo etching techniques are employed the lacquer coats can be easily removed from the enamel leaving the photo etched image. In the case of edge lighted instrument panels, a coat of uncured enamel is placed over the cured enamel followed by the lacquer coats and the photo resists which is exposed and developed. Once the etched uncured enamel is cured, the lacquer coats are removed leaving an etched panel

Fuhr, W.

English

NASA Technical Reports Server

United States Patent 
Fuhr 
[54] METHOD FOR APPLYING 
PHOTOGRAPHIC RESIST TO OTHERWISE 
INCOMPATIBLE SUBSTRATES 
1761 Inventor: Robert A. Frosch, Administrator of 
the National Aeronautics and Space 
Administration, with respect to an 
invention of Wolfgang Fuhr, North 
Haldon, V.J. 
[21] Appl. No.: 956,168 
[22] Filed: Oct. 31, 1978 
[51] Int. Cl.3 ................................................ W3C 5/00 
[52] U.S. Cl. .................................... 430/271; 430/325; 
[58] Field of Search ............................ 96/67, 36, 36.2; 
430/329; 430/330 
430/271, 325, 329, 330 
[561 References Cited 
U.S. PATENT DOCUMENTS 
2,726,200 12/1955 Holsapple ................................ 96/36 
3,545,973 12/1970 Goersma et al. ........................ 96/36 
3,547,629 12/1970 Kinney et al. ........................ 96/36.2 
3,808,001 4/1974 Konstantouros et al. ............... 96/36 
Primary Examiner-Won H. Louie, Jr. 
4,262,080 
1451 Apr. 14, 1981 
Attorney, Agent, or Firm-Edward K. Fein; John R. 
Manning; Marvin F. Matthews 
[571 ABSTRACT 
A new and improved method for applying photo- 
graphic resists to otherwise incompatible substrates, 
such as, for example, a baking enamel paint surface, is 
described wherein the uncured enamel paint surface is 
coated with a non-curing lacquer which is, in turn, 
coated with a partially cured lacquer. The non-curing 
lacquer adheres to the enamel and a photo resist mate- 
rial will satisfactorily adhere to the partially cured lac- 
quer. Once normal photo etching techniques are em- 
ployed the lacquer coats can be easily removed from the 
enamel leaving the photo etched image. This invention 
is particularly applicable to preparation of edge-lighted 
instrument panels. In such case a coat of uncured 
enamel is placed over the cured enamel followed by the 
lacquer coats and the photo resists which is exposed and 
developed in the normal way. Once the uncured 
enamel, now having had the image etched upon it, is 
cured, the lacquer coats are removed leaving an etched 
panel. 
3 Claims, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19810016673 2020-03-21T09:51:09+00:00Z
4,262,080 
1 2 
lacquer coats are removed to leave a beautifully etched 
instrument panel. 
DESCRIPTION OF THE PREFERRED 
EMBODIMENTS 
METHOD FOR APPLYING PHOTOGRAPHIC 
RESIST TO OTHERWISE INCOMPATIBLE 
SUBSTRATES 
5 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of section 305 of the National 
Aeronautics and Space Act of 1958, public law 85-568 ‘0 
(72 stat. 345; 45 U.S.C. 2457). 
The method of imparting an image to a substrate 
using photo resist techniques is well known and many 
such materials are available in the marketplace with 
instructions from the manufacturers for their use. 
Briefly, however, the photo resist material, in the 
absence of ultraviolet light, is applied to a substrate to 
which it adheres. A mask, either positive or negative, 
depending upon the nature of the photo resist material 
1. Field of the Invention being used, is placed over the photo resist material in 
The present invention relates to a method for apply- l5 the position at which the image is desired to be etched 
ing photo resists to an otherwise incompatible substrate. in the substrate. The photo resist is then exposed 
2. Description of the Prior Art through the mask to a source of ultraviolet light which 
The technique of applying images to substrates energizes a reaction in the photo resist rendering a part 
through the use of a photo resists has long been known of it soluble, the rest being insoluble, to selected sol- 
and many uses therefor currently exist, particularly in 2o vents. 
preparing printed circuits in a manner described in U.S. If the resist is a negative resist the material exposed to 
Pat. NO. 3,547,629, for example, or in making highly the ultraviolet light is rendered insoluble by the expo- 
sophisticated scientific apparatus such described in sure. is well known, the amount of exposure neces- 
U.S. Pat. No. 3,808,001, for example. These resists are sary is made followed by the development of the ex- 
also in the Preparation of various articles where an 25 posed resist by removing soluble materials. There is left 
image is desired such as, for example, edge-lighted Pan- then an image which can be imparted by treating, etch- 
ing, the substrate. In the case of metallic substrates the els such as are used as aircraft instrument panels. 
outgassing it is necessary to use baked enamel paints for 30 ducing step in the practice of this invention will be 
to be difficult since the photo resist material will not usual steps taken to restore the substrate to a adhere adequately to the baking enamel substrate to condition with the imparted These steps 
allow a proper image to be formed. While photo sensi- 35 
tive resist materials will adhere to a partially curd vary, of course, with respect to the substrates used and 
lacquer surface the lacquer will discolor when an un- the images desired. 
cured enamel is cured at elevated temperatures. I have It is the practice of this invention to provide a method 
which are normally incompatible substrates with which the resist is normally incompati- 
with the photo resist material, particularly substrates ble. It is known that most photo resist materials will 
painted with a baking enamel substrate. adhere to cured, or partially cured, lacquers but other 
substrates present somewhat of a problem. Accord- 
SUMMARY OF THE INVENTION ingly, in the practice of this invention such as incompat- 
can be applied to in- 45 ible substrate is first coated with a lacquer which is 
compatible substrates to be etched after development of uncurable in any of the subsequent Steps of treatment 
the photo resist, particularly enameled surfaces, by followed by applying a second coat of a lacquer which 
applying to such substrate a coat of a non-curing lac- is dried, in air or otherwise, to remove a portion of the 
quer followed by a coat of lacquer which is partially Solvent to make the lacquer compatible with the Photo 
cured. The photo resist material is applied to the par- 50 resist material. AS the term is used herein, the lacquer is 
tially cured lacquer coat. What f o ~ ~ o w s  is the normal “partially cured” but not cured to the point of becoming 
technique for exposing and developing the photo resist resistant to being removed by a solvent, i.e. acetone. 
and etching to impart an image to the substrate. Such lacquers are well known to those of ordinary skill 
In the instance of enameled instrument panels the in the art and generally, given the conditions under 
panel part painted with a cured enamel, usually white, is 55 which the invention is to be practiced, simple Selection 
painted with an enamel paint of contrasting color, usu- only is necessary for carrying out these Steps of the 
ally black or gray, which is not cured by baking. Upon invention. It is preferred, however, to use a clear lac- 
this uncured enamel substrate to be etched is applied a quer for both the first and second lacquer coats. 
coat of a non-curing lacquer followed by a coat of par- Once this outer layer of lacquer is partially cured it is 
tially cured lacquer. A photo resist, either positive or 60 coated with the desired photo resist material. AS has 
negative, is applied and exposed through an appropriate previously been stated many such materials are avail- 
mask, depending upon the nature of the photo resist. able and well known to those skilled in the art. Pre- 
After exposure, the photo resist is developed and the ferred photo resist materials are those negative resists 
lacquer and uncured enamel removed to provide the wherein the unexposed portions remain water soluble 
proper image bearing desired information on the panel. 65 such that development can be accomplished by use of a 
The enamel is then cured, fixing the image wherein the water spray. It has been found that the photo resist 
light colored enamel shows through the dark colored, material adheres very well to the partially cured lacquer 
contrasting, enamel. The balance of the photo resist and coating and, once the exposed photo resist is developed, 
BACKGROUND OF,THE INVENTION 
In certain such as, for ’pace image is generally imparted by acid etching to remove 
metal exposed by developing the resist. The image-pro- 
hereinafter described. Once the image is produced in 
the substrate the remaining resist is removed and the 
craft where there is a concern about flamability and 
such panels* However, etching such panels to 
images containing needed information has been found 
now discovered a method for applying photo resist whereby the photo resist material can be used with 
to 
photo sensitive resist 
4,262,080 
3 4 
the lacquer coats are easily removed by a spray of ace- Once all remaining resist is removed the part is then 
tone or some other appropriate solvent for the lacquer. baked to cure the outer coat of enamel on the panel 
Once these coats are removed the substrate previously making it solvent resistant. Once the enamel is cured by 
incompatible with photo resist materials can now be baking at known temperatures for a sufficient period of 
etched to form an image. The other steps which follow, 5 time to cure same, the lacquer coats are stripped from 
i.e. removal of the resist, any treatment of the substrate, the panel using an acetone spray at ambient tempera- 
and removal of the lacquer is well within the ordinary tures followed by a water rinse. The remaining part, i.e. 
skill in the art. the panel, thus has been photo etched to provide a dis- 
As a specific application of my invention, its use in play of information in white against a dark background 
connection with preparing an instrument panel having 10 which is suitable for illumination from the edges of the 
information etched therein using photo resist techniques panel. Of course, the Same part can be again subjected 
on a baking enamel substrate will be considered. Since it to the steps ofthe invention to provide yet another layer 
is desired in this particular application to have the im- of etched enamel, if desired to give a deeper image. 
ages etched into the Panel to appear as white on a dark Prior to this invention such was not possible since the 
background, i.e. black or gray, a Panel coated with a 15 photo resist material would not adhere to the enamel 
white baked enamel paint surface is chosen as the sub- substrate to be etched. 
strate. On the surface of such enamel is applied, prefera- While most of the steps in the practice of the method 
remove excess solvent. To this uncured enamel coat is 20 resist to uncured enamel to properly protect the enamel 
applied a first lacquer coat which is non-curing at the from attack and thinning from the solvents used to 
the two intermediate lacquer coats as described above. curs later in the practice of my invention. To this non- curing lacquer coat is applied a second lacquer coat As can be seen from the foregoing discussion of my which is partially cured. Such curing must not be so 25 invention many can be made thereof. From such great that the lacquer cannot be dissolved with acetone. discussions those skilled in the art will be able to make Clear lacquers are preferably used in the practice of my 
invention but it should be known that the use of clear many applications, variations and modifications thereof 
without departing from the spirit and scope of the ap- lacquers is not absolutely necessary. 
photo resist material is applied to the second lacquer 
coat; in the absence of ultraviolet light, of course. Any 
suitable photo resist known to those of ordinary skill in 
the art can be used. M ~ ~ ~ ~ ~ ~ ,  in the practice of this 
embodiment of my invention it is preferred to use a 35 patible$ comprising the steps Of: 
negative photo resist wherein a polyvinyl polymer is 
formed upon exposure to UV light since unexposed 
material, in the form of the desired image, is generally 
water soluble and conveniently removed through use of 
bly by spraying, a dark of this invention are known it was heretofore unknown 
uncured. Some drying Of be to how to achieve satisfactory adherence of the photo 
paint 'Oat which 'emains 
conditions Of baking the for curing which OC- develop the resist. 1 have solved that problem by using 
Once the second lacquer coat is partially cured a 30 pended I '. A method for a photo resist material to an 
uncured enamel paint-coated, baked enamel substrate 
with which the photo resist material is normally incom- 
aPP1ylng a first lacquer coating to the 
which first lacquer coating is uncurable at subse- 
quent processing conditions of baking the uncured 
enamel paint-coated baked enamel substrate for 
a water. spray. Preferably the lacquer coats and photo 
resists are all applied by spraying. 
The photo resist is exposed to ultraviolet light 
through a mask containing the images desired to be 
imparted on the edge lighted panel. While either posi- 
tive or negative images can be used the preferred em- 
bodiment of this invention involves employing a posi- 
tive image on top of the resist such that the exposed 
portion of the resist is cross-linked becoming generally 
insoluble when compared with the unexposed photo 
resist. Thus the image is transferred to the photo resist 
material which is then developed. In this case, water is 
used to develop the image, removing the unexposed 
resist. This is accomplised by merely spraying wash 
water on the panel. Other photo resist materials would 
require washing with a suitable solvent to develop the 
resist. 
This then exposes the lacquer coat which is sprayed 
with acetone and dissolved as is the uncured enamel 
paint coating beneath the lacquer and results in expos- 
ing the desired image in white through the dark un- 
cured enamel coating. The substrate having now been 
etched to form the desired images; the resist exposed to 
the UV light, and generallv insoluable as comDared 
40 curing; 
applying a second partially cured lacquer coating 
over the first lacquer coating; and 
applying to the partially cured second lacquer coat a 
water soluble photo resist material suitable for 
receiving an image by exposure to ultraviolet light 
through an appropriate mask which water soluble 
photo resist material normally will not adhere to an 
uncured enamel paint. 
2. A method for creating an image on an uncured 
50 enamel-paint coated, baked enamel suljstrate which 
applying an uncured enamel paint coat to the baked 
enamel substrate; 
applying a first lacquer coat to the uncured enamel 
paint coat which lacquer coat does not cure at 
enamel curing conditions; 
applying a second partially cured lacquer coat to the 
first lacquer coat; 
applying a photo resist material to the second par- 
tially cured lacquer coat, which photo resist mate- 
rial normally will not adhere to an uncured enamel 
paint; 
exposing the photo resist material to a source of ultra- 
45 
comprises the steps of: 
55 
60 
with the unexposed resist, is iemoved in the practke of 
this embodiment by spraying with a mixture of four 65 
parts water to one part 35% hydrogen peroxide at a 
temperature of about loo" F. (38" C.), plus or minus 20" 
F. (7" C.). 
violet light through an appropriate mask to form 
the image on the photo resist material; 
developing the image in the photo resist material; 
removing the lacquer coats and uncured enamel paint 
coat to uncover the baked enamel substrate in the 
4,262,080 5 6 
form of the image while the rest of the substrate enamel whereby the substrate remains displaying 
remains protected; the desired cured enamel image. removing the remaining photo resist material from 
the second lacquer coat; 3. The method of claim 2 wherein the mask has a 
curing the uncured enamel coat in the form of the 5 bositive image and a negative photo resist is used to 
image by baking at a sufiicient temperature for a 
time to cure such coat; and 
removing the remaining lacquer coats from the cured 
form the photo resist coat. 
* * * * *  
10 
15 
20 
25 
30 
35 
40 
45 
50 
55 
60 


Method for applying photographic resists to otherwise incompatible substrates

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server