The present invention relates to a method for preparing a through-hole that is bored in a circuit board and that is formed with a conductor for the insertion of a press-fit contact.
A typical press-fit contact 101 shown in
The press-fit contact 101 shown in
The attachment part 104 is sheared along the vertical axial line of the press-fit contact 101, and has leg parts 106 and 107 that are mutually shifted outward along the sheared surfaces. The leg parts 106 and 107 are formed so that these leg parts extend toward both the first terminal part 102 and the second terminal part 103 parallel to the vertical axial line of the press-fit contact 101 and converge from the areas just before the ends of the sheared surfaces. The leg parts 106 and 107 have gently curved longitudinal outer edge parts 109 and 110. Furthermore, connected parts 108 that are not sheared are formed in the areas where the leg parts 106 and 107 converge. Here, if the distance between the outer edge parts 109 and 110 of the leg parts 106 and 107 at the connected parts 108 is designated as D as shown in FIG. 8C, this distance D is equal to the diameter Hp of the through-hole 111 in a circuit board PCB shown in
Furthermore, as is shown in
However, when the leg parts 106 and 107 of the press-fit contact 101 are inserted into the through-hole 111 formed in the circuit board PCB, the outer edge parts 109 and 110 of the leg parts 106 and 107 (i.e., the outer edge parts 109 and 110 whose diameter is larger than the diameter D of the outer edge parts 109 and 110 at the connected parts 108) contact the corner edge (corner) of the copper film 112 at the insertion opening of the through-hole 111, so that the metal plating applied to these contacted surfaces of the outer edge parts 109 and 110 is stripped away in some cases. In cases where the copper film 112 is made of a copper alloy, in particular, not only is the hardness of the film great, but the corner edge of the film is also sharp; therefore, the peeling of the metal plating on the outer edge parts 109 and 110 often occurs.
Accordingly, it is desirable to avoid the contact between the outer edge parts 109 and 110 of the leg parts 106 and 107 and the corner edge of the copper film 112 by giving a bevel to the corner edge of the copper film 112 at the insertion opening of the through-hole 111, thus preventing the metal plating applied to the surfaces of the outer edge parts 109 and 110 from being stripped away.
The method disclosed in Japanese Utility Model Registration No. 3084452 for preparing a through hole is devised such that the corner edge of the inner circumferential surface of a through-hole formed in a circuit board is beveled, and this through-hole is subsequently filled with a conductive member.
The method disclosed in Japanese Utility Model Registration No. 3084452 for preparing a through hole is shown in
Furthermore, Japanese Utility Model Application Kokai No. S58-129663 discloses a method for preparing a through-hole, in which a through-hole to be plated for the attachment of a component is bored by drill cutting or press stamping, and subsequently shaped by beveling the surface on the side of the component.
As is shown in
However, the following problems have been encountered in the through-hole working methods disclosed in Japanese Utility Model Registration No. 3084452 and in Japanese Utility Model Application Kokai No. S58-129663:
Specifically, in the case of the method for preparing a through-hole disclosed in Japanese Utility Model Registration No. 3084452, the bevel 203a is given to both the upper and lower corner edges of the through-hole 203 by means of a polishing drill 204 such as an electrodeposited diamond drill. However, since the hard glass substrate 201 itself is treated by the polishing drill 204 in order to form the bevel 203a, there are cases in which the polishing drill 204 is worn away.
Furthermore, in the case of the method for preparing a through-hole disclosed in Japanese Utility Model Application Kokai No. S58-129663, there is no disclosure regarding the concrete method for working a through-hole, so that it is questionable whether a plated through-hole can be appropriately beveled, i.e., whether it is possible to perform beveling that prevents the peeling of the metal plating applied to the surfaces of the outer edge parts 109 and 110 of the press-fit contact 101 when the press-fit contact 101 shown in
Accordingly, the present invention was devised in light of the problems described above. An object of the present invention is to provide a method for preparing a through-hole which makes it possible to form in a circuit board a through-hole that does not strip the metal plating away at the time of the insertion of a press-fit contact, with the amount of wear of a jig minimized.
In order to solve the problems described above, the method for preparing a board through-hole (for the insertion of a press-fit contact) that is bored in a circuit board comprises forming the through-hole with a conductor on the inner surface of the through-hole, and beveling a corner edge of the through-hole following the formation of the conductor by the pressing a pointed jig into the corner edge.
In the method described above, since the method comprises a step of beveling the corner edge of the through-hole following the formation of the conductor, a beveled part is formed on the corner edge of the through-hole, thus making it possible to form in a circuit board a through-hole that does not strip the metal plating away when a press-fit contact is inserted, with the amount of wear of the jig minimized. If the corner edge of the through-hole is beveled prior to the formation of the conductor, there is a danger that the amount of wear of the jig will be increased in cases where the circuit board provided with the through-hole is a hard glass substrate. Furthermore, since the beveling work is performed by pressing the pointed jig, the time required for the beveling work is shortened compared to a case in which the beveling work is performed using a drill or the like.
Next, an embodiment of the present invention will be described with reference to the figures.
In
The positioner 10 comprises: a guide rail 12 that is fastened to the surface of a base frame 11 by a bolt 14, and a base stand 13 that can move along the guide rail 12 in the arrow direction in
Moreover, the beveling part 20 comprises a support 21 that is installed upright on the base frame 11. A ram support 22 is provided slightly upward in the vertical direction of the support 21. A rotating shaft 23 equipped with a pinion gear 24 is provided on the ram support 22 so that this shaft can be rotated, and a handle shaft 25 is attached to one end of the rotating shaft 23. An operating part 26 is attached to the tip end of the handle shaft 25. Furthermore, a ram 27 is disposed in the ram support 22 so that this ram 27 is free to move upward and downward with respect to the ram support 22. A rack 28 that meshes with the pinion gear 24 is provided on a portion of the outer circumference of the ram 27.
Furthermore, a hole 29 is bored in the lower end portion of the ram 27, and an attachment shaft 30 is disposed inside the hole 29. The attachment shaft 30 is fastened to the ram 27 by a screw 33. Moreover, a pressing head supporting plate 31 is disposed beneath the attachment shaft 30. The pressing head supporting plate 31 is fastened to the attachment shaft 30 by a bolt 32. A pressing head 34 is disposed beneath the pressing head supporting plate 31, and the pressing head 34 is fastened to the pressing head supporting plate 31 by a bolt 47. A through-hole 35 that passes through in the vertical direction is bored in the pressing head 34, and a female screw thread 36 is formed in the lower portion of the through-hole 35. Furthermore, a pointed jig 37 is disposed inside the through-hole 35 so that this jig can move up and down, and the downward movement of the jig 37 is restricted by a hollow cylindrical jig support 38 that engages with the female screw thread 36. The jig support 38 is prevented from rotating by a screw 40.
The jig 37 comprises a shaft 37a that is accommodated inside the jig support 38, a tubular part having a bottom 37b that extends upward from the shaft 37a, and a pointed press 37c that extends downward from the shaft part 37a, all of which are integrally constructed. The material of the jig 37 is ordinary tool steel. The external diameter of the tubular part having a bottom 37b is larger than the external diameter of the shaft 37a, and the downward movement of the jig 37 is restricted by a shoulder that is formed at the lower end of the tubular part having a bottom 37b sitting on the jig support 38. A compression spring 39 whose upper end contacts the undersurface of the pressing head supporting plate 31 and whose lower end contacts the bottom of the tubular part having a bottom 37b is inside the tubular part having a bottom 37b, and the jig 37 is driven downward (in the direction of the corner edge of the through-hole 50) by this compression spring 39. The external diameter of the press 37c is smaller than the external diameter of the shaft 37a, and a pointed corner edge press 37d that presses the corner edge of the through-hole 50 formed in the circuit board PCB is formed at the lower end of the press 37c. It is preferable that the angle θ formed by the ridgeline of the corner edge press 37d be about 30° to 90°. The reason for this is that if this angle θ is smaller than 30°, the angle is too sharp to form a bevel 52 in an appropriate shape (see
Moreover, a rotation stop 41 for preventing rotation of the ram 27 and pressing head 34 is attached to the pressing head supporting plate 31 by a bolt 42. The rotation stop 41 prevents the ram 27 and pressing head 34 from rotating by contacting a rotation stop 43 provided on the supporting part 21.
Meanwhile, a stopper attachment 44 is fastened to the upper end portion of the ram 27, and a stopper bolt 45 that restricts the downward movement of the ram 27 is attached to the stopper attachment 44 by a nut 46. The stopper bolt 45 restricts the downward movement of the ram 27 by contacting the upper end surface of the ram support 22 when the ram 27 moves downward. The position of the stopper bolt 45 in the vertical direction is made adjustable.
A method for beveling the through-hole 50 formed in the circuit board PCB using the apparatus 1 constructed as described above will be described with reference to
Prior to the beveling work described above, a conductor 51 is formed on the inner wall surface of the through-hole 50 bored in the circuit board PCB. Furthermore, the circuit board PCB containing the through-hole 50 having the conductor 51 formed on the inner wall surface thereof is placed on the board carrying stand 18, and the positioning of the circuit board PCB in the x and y directions is performed by the positioner 10.
Next, the operating part 26 of the beveling part 20 is rotated in the arrow direction A in
If the corner edge of the through-hole 50 is beveled prior to the formation of the conductor 51, there is a danger that the amount of wear of the jig 37 will increase in cases where the circuit board PCB in which the through-hole 50 is bored is a hard glass substrate. In contrast, since the beveled part 52 is formed on the upper corner edge of the conductor 51 on the through-hole 50 following the formation of the conductor 51 on the inner wall surface of the through-hole 50, the through-hole 50 that does not strip the metal plating away during the insertion of the press-fit contact 101 (see
Moreover, in the step in which the corner edge press 37d of the jig 37 presses the corner edge of the conductor 51 formed on the through-hole 50 in the circuit board PCB, the jig 37 is spring driven toward the direction of the corner edge of the through-hole 50 while receiving an upward force from below (from the circuit board PCB toward the jig 37). Accordingly, the pressing force of the jig 37 against the corner edge of the through-hole 50 can be made constant. As a result, the shape of the bevel 52 formed by this beveling work can be stabilized.
Furthermore, the circuit board PCB that has completed the beveling of the through-hole 50 is removed from the board carrying stand 18, and this circuit board PCB is sent to the subsequent step.
Alternatively, instead of providing the interior of the tubular part having a bottom 37b with the compression spring 39, as is shown in
Furthermore, as is shown in
An embodiment of the present invention was described above. However, the present invention is not limited to this embodiment; various alterations and modifications can be made.
For example, the bevels 52 are formed with portions of the conductor 51 remaining as shown in
Moreover, the bevels 52 are formed on the upper corner edge of the conductor 51 as shown in
Number | Date | Country | Kind |
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2004-075155 | Mar 2004 | JP | national |