Patent Publication Number: US-6981315-B2

Title: Method of manufacturing a flexure blank

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a divisional of and claims priority of U.S. application Ser. No. 09/513,353 filed on Feb. 25, 2000, now U.S. Pat. No. 6,500,011, issued Dec. 31, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a flexure blank for constructing a suspension for a circuit wire integrated type magnetic and a method of manufacturing the same and particularly to a flexure blank structured such as to be electrically connected with a relay flexible circuit board for connecting to an external circuit in a reliable manner, and a method of manufacturing the same. 
   2. Description of the Related Art 
   This kind of suspension for the circuit wire integral type magnetic head is constituted by a load beam and a flexure blank, and the flexure blank is connected to an external circuit via the relay flexible circuit board. 
     FIG. 2  is a cross sectional view which shows a schematic arrangement of the connecting portion of the flexure blank mentioned above and the relay flexible circuit board. A terminal portion or the connecting portion of the conventional flexure blank is structured such that an opening portion  22  for connection is provided at a predetermined position of an insulating base layer  20  made of a polyimide resin or the like, a conductive layer  23  made of a copper or the like and including a predetermined circuit wire pattern is formed on an upper surface of the insulating base layer  20  in such a manner as to surround the opening portion  22 , and as shown in  FIG. 2 , an anticorrosive conductive layer  25  made of a gold or the like is formed on an upper surface of the conductive layer  23  in this connecting portion via a barrier conductive layer  24  made of a nickel or the like. 
   The conductive layer  23 , the barrier conductive layer  24  and the anticorrosive conductive layer  25  mentioned above can be formed in accordance with an additive method such as an electrolytic plating or the like, and this kind of flexure blank is coated with a surface protecting layer  26  made of a polyimide resin or the like including the circuit wire pattern in such a manner as to properly expose the connecting portion mentioned above. 
   However, in accordance with the structure of the connecting portion of the flexure bland mentioned above, there is a case that an end portion  21  of the insulating base layer  20  positioned at the opening portion  22  for connection protrudes and is formed so as to fringe the conductive layer  23 , the barrier conductive layer  24  and the anticorrosive conductive layer  25  in the opening portion  22 . 
   As mentioned above, when the end portion  21  of the insulating base layer  20  protrudes to the opening portion  22  for connection, there is generated a case that a solder is neither sufficiently applied nor expended to a whole of the connecting portion constituted by the conductive layer  23 , the barrier conductive layer  24  and the anticorrosive conductive layer  25  and an electric connection can not reliably performed since a wetting property of a solder  29  is bad in the protruding end portion  21  of the insulating base layer  20  in the case of bringing the relay flexible circuit board for connecting to the external circuit in which a predetermined circuit wire pattern  28  is formed on an upper surface of the insulating base member  27  into contact with the opening portion  22  in the connecting portion of the flexure blank mentioned above by using the solder  29  in the manner shown by an arrow. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention provides a flexure blank having a connecting portion which can be electrically connected to a relay flexible circuit board for connecting to an external circuit in a reliable manner, and a method of manufacturing the same. 
   In accordance with the present invention, there is provided a flexure blank of a suspension for a circuit wire integral type magnetic head which is electrically connected to a relay flexible circuit board for connecting to an external circuit, wherein an opening portion is provided in a connecting portion of the flexure blank, and an opening end portion of an insulating base layer is coated with a conductive member without exposing the opening end portion of the insulating base layer in the connecting portion. 
   In this case, a lower surface of the conductive member of the opening portion in the connecting portion of the flexure blank can be structured such as to form the same surface as the lower surface of the insulating base layer, and the lower surface of the conductive member of the opening portion in the connecting portion can be constructed by a grounding conductive layer made of a chrome. 
   Then, the flexure blank of this kind can be manufactured in accordance with steps of forming an insulating base layer in a pattern which can form an opening portion necessary for a connection with a relay flexible circuit board used for connecting to an external circuit, on an upper surface of a spring metal layer, at least forming a grounding conductive layer which has an improved solder wetting property and is not corroded by an etching fluid in an etching step with respect to an unnecessary portion of the spring metal layer, on a surface of the insulating base layer and a surface area of an exposed spring metal layer by sputtering means, next, forming a plating resist pattern at a position of forming the opening portion on the surface of the grounding conductive layer, successively forming a desired conductive layer and anticorrosive conductive layer in the connecting portion by electrolytic plating means at a stage of forming the other plating resist patterns in accordance with a pattern which can form the connecting portion, thereafter, peeling and removing the plating resist pattern, further, etching and removing an unnecessary area of the grounding conductive layer so as to form the connecting portion, thereafter, peeling and removing the etching resist pattern which becomes unnecessary at the etching process so as to form the opening portion in the connecting portion, next, etching and removing an unnecessary area of the spring metal layer including the connecting portion, and finally etching and removing an area of the grounding conductive layer which is exposed to the opening portion so as to form a penetrating opening portion in the connecting portion. 
   In this case, at a stage of etching and removing the unnecessary area of the grounding conductive layer so as to form the connecting portion, it is possible to form a surface protecting layer in such a manner as to properly expose the connecting portion including the other circuit wire pattern, and the grounding conductive layer can be formed by a sputtering using a chrome. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a  to  1   e  are schematic views which show a manufacturing step for manufacturing a flexure blank in accordance with the present invention; and 
       FIG. 2  is a cross sectional view which shows a schematic arrangement of a connecting portion of a flexure blank and a relay flexible circuit board in accordance with a conventional art. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A description will be in detail given below of the present invention with reference to an illustrated embodiment.  FIGS. 1   a  to  1   e  are schematic views which show a manufacturing step for manufacturing a flexure blank in accordance with the present invention, in these drawings, a connecting portion in the flexure blank will be schematically illustrated. 
   At first, as shown in  FIG. 1   a , the steps are constituted by forming an insulating base layer  2  made of a polyimide resin on an upper surface of a spring metal layer  1  made of a stainless steel in accordance with a pattern which can form an opening portion necessary for a connection with a relay flexible circuit board which is used for connecting to an external circuit, uniformly forming a grounding conductive layer  3  made of a chrome or the like which has an improved solder wetting property and is not corroded by an etching fluid at an etching process with respect to an unnecessary portion of the spring metal layer  1 , on a surface of the insulating base layer  2  and a surface area of an exposed spring metal layer  1  by sputtering means, and further, forming a conductive layer  4  made of a copper or the like on a surface of the grounding conductive layer  3  by the same sputtering means. 
   Then, as shown in  FIG. 1   b , the steps are further constituted by forming a plating resist pattern  5  at a position of forming the opening portion on the surface of the conductive layer  4 , successively forming a conductive layer  7  made of a copper or the like, a barrier conductive layer  8  made of a nickel or the like and an anticorrosive conductive layer  9  made of a gold or the like by electrolytic plating means at a stage of forming the other plating resist patterns  6  in accordance with a pattern which can form the connecting portion in accordance with an application of a liquid resist, a drying process and an exposing and developing process, respectively. 
   Next, after peeling and removing the plating resist patterns  5  and  6 , the steps are constituted by etching and removing an unnecessary area of the conductive layer  4  formed by the sputtering means and an unnecessary area of the grounding conductive layer  3  respectively using a suitable acid and using an alkaline fluid such as a potassium ferricyanide or the like by slight etching means in a state of forming the etching resist pattern at a portion where the plating resist pattern  5  is peeled and removed, so as to form the connecting portion, and peeling and removing the etching resist pattern which becomes unnecessary, whereby the opening portion  10  is formed in the portion as shown in  FIG. 1   c . Then, as shown in  FIG. 1   c , a surface protecting layer  11  is formed by using a polyimide resin or the like together with the other circuit wire patterns in an aspect of properly exposing the connecting portion formed in the above steps. 
   Next, when etching and removing the area of the exposed spring metal layer  1  at a stage of forming the etching resist in a pattern which can remove a whole of an upper surface of the connecting portion formed in the step shown in  FIG. 1   c  and the unnecessary area on an outer surface of the spring metal layer  1 , the area of the spring metal layer  1  in the connecting portion of the flexure blank is also removed at the same time as shown in  FIG. 1   d . Since the grounding conductive layer  3  is formed by the member such as a chrome or the like, the portions of the grounding conductive layer  3  and the conductive layer  4  which are positioned in the opening portion  10  are not etched and removed at this etching process, whereby the lower surface to which the grounding conductive layer  3  is exposed becomes the same surface as the lower surface of the insulating base layer  2 . 
   Then, by applying a slight etching process to the area of the conductive layer  4  and the grounding conductive layer  3  which are positioned in the opening portion  10  respectively by using the acid and alkaline fluid as shown in  FIG. 1   e  after peeling and removing the etching resist, it is possible to form a penetrating opening portion in the connecting portion. 
   In accordance with the flexure blank obtained by the step shown in  FIG. 1   e , since the opening end portion of the insulating base layer  2  in the connecting portion having the opening portion  12  which is connected to the relay flexible circuit board for connecting to the external circuit is coated with the conductive layer including the grounding conductive layer  3  without exposing and the opening end portion of the opening portion  12  is substantially constructed by the conductive member, the solder is directly brought into contact with the conductive member at a time of connecting to the relay flexible circuit board so as to improve the solder wetting property, so that it is possible to electrically connect the connecting portion of the flexure blank to the relay flexible circuit board in a reliable manner. 
   In accordance with the flexure blank and the method of manufacturing the same of the present invention, since the structure can be made such as to securely cover the opening end portion of the insulating base layer by the conductive member without exposing the opening end portion of the insulating base layer to the end portion of the opening portion in the connecting portion of the flexure blank, the solder is directly brought into contact with the conductive member at a time of connecting to the relay flexible circuit board for connecting to the external circuit so as to improve the solder wetting property, so that it is possible to properly solve the problem of a poor soldering connection in the conventional art so as to electrically connect the connecting portion of the flexure blank having the structure mentioned above to the relay flexible circuit board in a reliable manner. 
   Further, since the lower surface of the conductive member of the opening portion in the connecting portion of the flexure blank is formed in the same surface as the lower surface of the insulating base layer, it is possible to closely attach to the relay flexible circuit board so as to obtain an electrically and mechanically reliable mutual connection.