Patent Application
20070146974
The present invention relates to the formation of electrical circuit lines on electronic devices. More particularly, the invention relates to the use of a novel mold design to create the desired circuit design in the mold from which the electrical device or part is made.
A wide variety of electronic devices are currently being manufactured and many of them require electrical circuit lines to be defined on a plastic part. Examples of these devices are valves, pumps and sensors made from plastic, such as the family of meso devices such as electrostatic actuators, pumps arrays and the like.
In these devices, the parts are molded and then electrical circuit lines are pattern coated using metallization, either through a patterned additive process or a blanket addition and patterned subtraction process. These methods are very common in the manufacture of many electronic devices.
It would be of advantage in the art if a simple process could be developed that would eliminate the need for a second step in forming circuit lines in such electronic devices.
Another advantage would be if a method could be developed that would allow for a simple metallization step to be performed after formation of a patterned substrate for the electronic device.
Other advantages will appear hereinafter.
It has now been discovered that the above and other advantages of the present invention may be obtained in the following manner. Specifically, the present invention provides for inclusion of a circuit design in an injection mold prior to molding the electronic part. This permits the elimination of costly use of pattern coated metallization through patterned additive or subtraction processes.
The method of forming the electronic part having a circuit pattern is done in a conventional manner except that the cavity mold includes trench lines having a first area perpendicular to an axis and a second area having a negative slope with respect to the axis. After the part is molded and removed, a conductive material is deposited to form conductive and nonconductive areas thereon which make up the desired circuit pattern. The electronic part is any molded device made from plastic or other nonconductive materials such as, by way of example and not as a limitation, mesovalves, dual chamber mesovalves, meso arrays, printed circuit boards, printed circuit boards with conductive access to a back side and the like.
The preferred deposit step is by blanket metallization which coats all surfaces except the sides of the trench lines and the second area of the part.
The method may include the additional step of molding vertical flash portions on the part instead of or in addition to the trench lines that are removed after the conductive material is deposited thereon to form the circuit pattern. Blanket metallization is a preferred method of applying the conductive material and a beam process is most preferred to coat all surfaces except the sides of the trench lines and the second area of the part formed by the mold.
Another embodiment of the present invention includes filling the trench lines with a nonconductive material in the part after removing the part from the mold and prior to depositing the conductive material thereon. Preferably the nonconductive material does not adhere to the part.
The present invention includes an alternative step of molding vertical flash portions with respect to said axis on said part instead of or in addition to the trench lines and removing the vertical flash portions after the conductive material is deposited thereon to form the circuit pattern
For a more complete understanding of the invention, reference is hereby made to the drawings, in which:
a and 8B are side elevational views of an alternative embodiment of the present invention.
The present invention provides for a method of forming an electrical circuit on an electronic part in a manner that is faster, more economical and more precise.
The part has been formed by molding in an injection molding process in which the areas 21 have a negative slope with respect to axis 18. By negative slope is meant having a slope or shape that moves toward the axis 18, as seen in
In
While particular embodiments of the present invention have been illustrated and described, it is not intended to limit the invention, except as defined by the following claims.
