Abstract:
An etching device capable of forming a uniform etchant film. The etching device is disposed on a plurality of parallel and coplanar hollow sheet-type rollers used to support a double-sided board. A plurality of first etchant nozzles is disposed under the hollow sheet-type rollers. The device has several solid rollers, several rows of second etchant nozzles and several rows of air nozzles. The solid rollers are coplanarly disposed over the hollow sheet-type rollers and are parallel to each other. The adjacent solid rollers comprise an interval, and the intervals are divided into several first intervals and several second intervals. The solid rollers touch the double-sided board to make an etchant film covering the double-sided board more uniform. The rows of second etchant nozzles are disposed over the first intervals and parallel to axes of the solid rollers. The rows of air nozzles are disposed over the second intervals and parallel to the axes of the solid rollers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to an etching device. More particularly, the present invention relates to an etching device capable of forming an uniform etchant film. 
     2. Description of Related Art 
     Typically, the laminate substrate used to manufacture a printed circuit board is formed by pressing together several doable-sided boards. The double-sided board comprises alternating layers of an insulating layer and two circuit layers. The method of respectively forming the circuit layers on each side of the insulating layer comprises the steps of forming a copper layer on each side of the insulating layer, and then patterning the copper layers by a photolithography process and an etching process to form a circuit layer on each side of the insulating layer, respectively. 
     FIG. 1A is a schematic, top view of a double-sided board when copper layers on both sides of the insulating layer are converted into circuit layers by using a conventional etching device. FIG. 1B is a cross-sectional view along a line I—I in FIG.  1 A. 
     As shown in FIG. 1A together with FIG. 1B, a double-sided board  104  constituting alternating layers of an insulating layer  100  and copper layers  102   a  and  102   b  is provided. After performing a photolithography process, a wet etching process is performed to pattern the copper layers  102   a  and  102   b . In the wet etching process, the double-sided board  104  is supported by several hollow sheet-type rollers  106   b  and contacts the hollow sheet-type rollers  106   b  through the copper layer  102   b  (as shown in FIG.  1 A). While the wet etching process is performed, the hollow sheet-type rollers  106   b  are driven to roll by axles  106   a  and the double-sided board  104  levelly moves in a direction indicated by an arrow  110 . Additionally, nozzles  114  spray etchant  108   a  onto the copper layers  102   a  and  102   b . The etchant  108   a  is conically sprayed from the nozzles  114  in a swing fashion at a fixed point or in a to-and-fro horizontally fashion onto the copper layers  102   a  and  102   b . Aternatively, the etchant  108   a  is sprayed from angled nozzles (not shown) in a swing fashion at a fixed point or in a to-and-fro horizontally fashion onto the copper layers  102   a  and  102   b . Therefore, a lot of liquid  108   b  corresponding to the nozzles  114  is formed on the copper layer  102   a  to perform the wet etching process. 
     However, the etchant easily agglomerates to form a nonuniform etchant film  112  on the copper layer  102   a , such that the thickness of the nonuniform etchant film  112  on the margin of the double-sided board  104  is larger than that in the center of the double-sided board  104 . The appearance is called a fountain effect. Since thickness of the etchant film is nonuniform, the etching rate in the margin region of the double-sided board  104  is different from that of the central region of the double-sided board  104 . 
     FIG. 2 is a contour diagram of the copper layer  102   a  after the etching process is performed. Obviously, the etchant film  112  in the central region of the double-sided board  104  is relatively thick, so that the etchant used in the central region of the double-sided board is not easily refreshed. Therefore, the etching result in the central region of the double-sided board  104  is relatively poor. Nevertheless, the etchant film  112  in the margin region of the double-sided board  104  is relatively thin, so that the etchant in the margin region of the double-sided board is often fresh. Hence, the etching result in the margin region of the double-sided board  104  is relatively good. Altogether, the thickness of the copper layer  102   a  in the central region of the double-sided board  104  is larger than that in the margin region of the double-sided board  104 . 
     Conventionally, in order to move the double-sided board  104  along the direction indicated by arrow  110  more easily, several hollow sheet-type rollers  120  (as shown in FIG. 3) are disposed on the copper layer  102   a . But the relative motion between the hollow sheet-type rollers  120  and the double-sided board  104  disrupts the flux of the etchant. Therefore, the etchant film is still nonuniform and the etching result of the copper layer  102   a  is still poor. 
     Additionally, in order to overcome the problem due to the fountain effect, another conventional etching device is provided, where the etchant is sectorially sprayed with a particular angle onto the double-sided board. Therefore, the etchant on the copper layer agglomerates to form an etchant flax. Moreover, several hollow sheet-type rollers are disposed on the double-sided board to assist the motion of the double-sided board (the cross-section of the device described above is similar to FIG.  3 ). However, the relative motion between the hollow sheet-type rollers and the double-sided board disrupts the flux of the etchant. Hence, the thickness of the etchant film is still nonuniform. 
     SUMMARY OF THE INVENTION 
     The invention provides an etching device capable of forming a uniform etchant film. The etching device is disposed on a plurality of parallel and coplanar hollow sheet-type rollers used to support a double-sided board, wherein a plurality of first etchant nozzles is disposed under the hollow sheet-type rollers. The device comprises several solid rollers, several rows of second etchant nozzles and several rows of air nozzles. The solid rollers are coplanarly disposed over the hollow sheet-type rollers and are parallel to each other. The adjacent solid rollers comprise an interval, and the intervals are divided into several first intervals and several second intervals. The solid rollers touch the double-sided board to make an etchant film covering the double-sided board more uniform. The rows of second etchant nozzles are disposed over the first intervals and parallel to axes of the solid rollers. The rows of air nozzles are disposed over the second intervals and parallel to the axes of the solid rollers. 
     As embodied and broadly described herein, the first and the second intervals are alternatively disposed. Additionally, every row of the second etchant nozzles comprises several etchant nozzles and the etchant nozzles spray an etchant with an angle in the corresponding first intervals to form an etchant flux parallel to the axes of the solid rollers. The etchant flux flows from one end of the first interval corresponding to the axis of the solid roller to the other end of the first interval corresponding to the axis of the solid roller. Alternatively, the etchant flux flows from a central portion of the first interval corresponding to the axis of the solid roller to the margin of the first interval corresponding to the axis of the solid roller. Moreover, the the etchant flux in the adjacent first intervals flows in different directions. 
     Since the solid rollers touch the double-sided board, the etchant sprayed from the rows of the etchant nozzles can uniformly cover the double-sided board. Incidentally, the flux in the adjacent etchant spraying regions flows in different directions, so that the etchant may not agglomerate to manifest the fountain effect. Hence, the thickness of the etchant film on the double-sided board can be effectively decreased and the etching result of the double-sided board can be greatly improved. 
     Additionally, in some first intervals, the etchant flux flows from the central part to the margin of the first interval corresponding to the solid rollers, so that the thickness of the etchant film in the central part is decreased and the fountain effect can be avoided. Moreover, because air is puffed from the air nozzles sweeping over the double-sided board in the second intervals, the used etchant can be quickly removed. Therefore, the reaction probability between a conductive layer of the double-sided board and the fresh etchant is greatly increased. By sweeping away the etchant, the fountain effect can be avoided and the etching uniformity of the conductive layer is improved. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, 
     FIG. 1A is a schematic, top view of a double-sided board when copper layers on both sides of the insulating layer are converted into circuit layers by using a conventional etching device; 
     FIG. 1B is a cross-sectional view along a line I—I in FIG. 1A; 
     FIG. 2 is a contour diagram of the copper layer  102   a  after the etching process is performed; 
     FIG. 3 is a cross-sectional view of another conventional etching device while an etching process is performed; 
     FIG. 4A is a schematic, top view of an etching device according to the invention with a double-sided board when conductive layers of the double-sided board are converted into circuit layers by performing an etching process; 
     FIG. 4B is a cross-sectional view along a line II—II in FIG. 4A; and 
     FIG. 5 is a cross-sectional view of another etching device according to the invention while an etching process is performed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 4A is a schematic, top view of an etching device according to the invention with a double-sided board when conductive layers of the double-sided board are converted into circuit layers by performing an etching process. FIG. 4B is a cross-sectional view along a line II—II in FIG.  4 A. 
     As shown in FIG. 4A together with FIG. 4B, a double-sided board  204  comprising alternating layers of an insulating layer  200  and conductive layers  202   a  and  202   b  is provided. After performing a photolithography process, a wet etching process is performed to pattern the conductive layers  102   a  and  102   b . The double-sided board  204  can be a hard substrate and the insulating layer  200  can be made of bismaleimidetriazine (BT), FR-4 or FR-5 (flame-retardant epoxy-glass fabric composite resin), for example. Moreover, the conductive layers  202   a  and  202   b  can be made of copper, for example. 
     The etching device according to the invention comprises several hollow sheet-type rollers  206   b , several solid rollers ( 222   a ,  222   b ,  222   c ,  222   d ,  222   e  and  222   f ), several rows of etchant nozzle  214 ,  224   a ,  224   b  and  224   c  and several rows of air nozzles  226   a  and  226   b . Every row of the etchant nozzles comprises several etchant nozzles and every row of the air nozzles comprises several air nozzles. 
     In the wet etching process, the double-sided board  204  is supported by the hollow sheet-type rollers  206   b  and touches the hollow sheet-type rollers  206   b  through the conductive layer  202   b . While the wet etching process is performed, the hollow sheet-type rollers  206   b  are driven to roll by axles  206   a  and the double-sided board  204  levelly moves in a direction indicated by an arrow  210 . 
     The solid rollers  222   a ,  222   b ,  222   c ,  222   d ,  222   e  and  222   f  are disposed in the same plane on the conductive layer  202   a . Each axis of the solid roller is perpendicular to the motion direction  210  of the double-sided board  204  and the axes of the solid rollers are parallel to each other. The solid rollers are used to smooth the subsequently formed etchant film, so that the etchant film can evenly cover the double-sided board  204 . The solid rollers can be made of a soft material, for example. 
     Taking the solid rollers  222   a ,  222   b ,  222   c ,  222   d ,  222   e  and  222   f  as a basis for division, the space over the double-sided board  204  is divided into etchant spraying regions  240   a ,  240   c  and  240   e  (the first interval) and air knife regions  240   b  and  240   d  (the second interval). The etchant spraying regions  240   a ,  240   c  and  240   e  are respectively located between the solid rollers  222   a  and  222   b , between the solid rollers  222   c  and  222   d  and between the solid rollers  222   e  and  222   f  (as shown in FIG.  4 A). Moreover, the air knife regions  240   b  and  240   d  are respectively located between the solid rollers  22   b  and  222   c  and between the solid rollers  222   d  and  222   e  (as shown in FIG.  4 A). pecifically, the space over the double-sided board  204  comprises the alternating regions of the etchant spraying regions (those are the etchant spraying regions  240   a ,  240   c  and  240   e ) and the air knife regions (air knife regions  240   b  and  240   d ). 
     The etchant spraying regions  240   a ,  240   c  and  240   e  respectively comprise the rows of the etchant nozzles  224   a ,  224   b  and  224   c . The air knife regions  240   b  and  240   d  respectively comprise the rows of the air nozzles  226   a  and  226   b . In other words, the rows of the etchant nozzles ( 224   a ,  224   b  and  224   c ) are altematingly disposed with the rows of the air nozzles ( 226   a  and  226   b ). Furthermore, the etchant nozzles  214  are located under the conductive layer  202   b  of the double-sided board  204  to perform the etching process on the conductive layer  202   b.    
     During the etching process, the row of the etchant nozzles  224   a  sprays etchant  242  with a specific angle onto the conductive layer  202   a  in the etchant spraying region  240   a . Therefore, the etchant sprayed onto the conductive layer  202   a  forms a flux flowing in a direction indicated by an arrow  228  and parallel to the axes of the solid rollers  224   a  and  224   b.    
     Similarly, in the etchant spraying region  240   e , the row of the etchant nozzles  224   c  sprays etchant  242  with a specific angle onto the conductive layer  202   a , so that the etchant sprayed onto the conductive layer  202   a  forms a flux flowing in a direction indicated by an arrow  234  and parallel to the axes of the solid rollers  224   e  and  224   f . 
     Meanwhile, in the etchant spraying region  240   c , the row of the etchant nozzles  224   b  sprays etchant  242  with a specific angle onto the conductive layer  202   a . Hence, the etchant sprayed onto the conductive layer  202   a  forms a flux flowing from the central portion of the double-sided board  204  to the margins of the double-sided board  204  in directions respectively indicated by arrows  232  and  230  and parallel to the axes of the solid rollers  224   c  and  224   d . Specifically, the the etchant flux in the adjacent etchant spraying regions flows in different directions. 
     Air is puffed from the row of the air nozzles  226   a  with a specific angle in the air knife region  240   b  onto the conductive layer  202   a  to form air current sweeping over the conductive layer  202   a  in a direction indicated by an arrow  236  and parallel to the axes of the solid rollers  224   b  and  224   c . Identically, air is puffed from the row of the air nozzles  226   b  with a specific angle in the air knife region  240   d  onto the conductive layer  202   a  to form air current sweeping over the conductive layer  202   a  in a direction indicated by an arrow  238  and parallel to the axes of the solid rollers  224 d and  224   e . It should be noted that the air currents in the adjacent air knife regions flow in different directions. 
     Moreover, the direction of the air current in the air knife region  240   b  is the same as that of the flux in the etchant spraying region  240   a . Furthermore, the direction of the air current in the air knife region  240   d  is the same as that of the flux in the etchant spraying region  240   e . However, it is unnecessary to make the direction of the air current in the air knife region the same as that of the flux in the etchant spraying region. The direction of the air current only needs to smoothly remove the etchant from the double-sided board  204 . 
     Since the solid rollers  222   a ,  222   b ,  222   c ,  222   d ,  222   e  and  222   f  are disposed on the conductive layer  202   a  of the double-sided board  204  and the double-sided board  204  is levelly moved by the hollow sheet-type rollers  206   b , the etchant  242  sprayed from the rows of the etchant nozzles  224   a ,  224   b  and  224   c  can uniformly cover the conductive layer  202   a . Incidentally, the flux in the adjacent etchant spraying regions flows in different directions, so that the etchant  242  may not agglomerate to manifest the fountain effect. Hence, the thickness of the etchant film on the conductive layer  202   a  can be effectively decreased and the etching result of the conductive layer  202   a  can be greatly improved. 
     Additionally, in the etchant spraying region  240   c , the etchant flux flows from the central portion of the double-sided board  204  to the margins of the double-sided board  204 , so that the thickness of the etchant film in the central portion is decreased and the fountain effect can be avoided. Moreover, because of the air currents sweeping over the conductive layer  202   a  in the air knife regions  226   a  and  226   b , the etchant which has reacted with the conductive layer  202   a  can be quickly removed. Therefore, the reaction probability between the conductive layer  202   a  and the fresh etchant is greatly increased. By sweeping away the etchant, the fountain effect can be avoided and the etching uniformity of the conductive layer is improved. 
     In the present embodiment, every etchant spraying region comprises a row of the etchant nozzles (as shown in FIG.  4 B). However, in the application, every etchant spraying region can comprise more than two rows of the etchant nozzles (as shown in FIG. 5, the etchant nozzles  234   a ,  234   b  and  234   c ). 
     The embodiment according to the invention is one of the preferred etching devices. People skilled in the art may know that the combination of the etchant spraying regions and the air knife regions in the invention can be also reorganized to achieve the goal and the spirit of the invention. The preferable rule for combination of the etchant spraying regions and the air knife regions in the invention is that the rows of the etchant spraying nozzles and the row of the air nozzles are altematingly and respectively disposed over the interval between the solid rollers. Additionally, the rows of the etchant spraying nozzles and the rows of the air nozzles are parallel to the axes of the solid rollers. Preferably, the etchant flux in the adjacent etchant spraying regions flow in different directions. Moreover, the air currents in the adjacent air knife regions flow in different directions. Incidentally, the direction of the etchant flux in the etchant spraying region is not limited by the embodiment and the direction of the etchant flux; all that is required is that the rule that the etchant flux in adjacent etchant spraying regions flows in different directions be followed in order to smoothly remove the used etchant. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.