BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A through 1D are pictorial stepwise representations showing a procedure for forming through-holes through a green sheet by a machining apparatus of a first exemplary embodiment of the invention.
FIG. 2 is a section view of a main part of a through-hole perforating step in the first exemplary embodiment.
FIG. 3 is a pictorial representation for explaining a step of interposing a green sheet of a machining apparatus according to a second exemplary embodiment of the invention.
FIG. 4 is a pictorial representation for explaining a through-hole perforating step in the second exemplary embodiment.
FIGS. 5A through 5C are pictorial stepwise representations showing a procedure for forming through-holes through a green sheet by a machining apparatus of a third exemplary embodiment of the invention.
FIGS. 6A through 6C are pictorial stepwise representations showing a procedure for forming through-holes through the green sheet by the machining apparatus of the third exemplary embodiment.
FIG. 7 is a section view of a main part of a lower base in the third exemplary embodiment.
FIG. 8 is a pictorial representation for explaining the lower base provided for the machining apparatus according to a forth exemplary embodiment of the invention.
FIG. 9 is a section view of a main part of the lower base.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the invention will be explained with reference to the drawings, wherein FIGS. 1A through 1D are pictorial stepwise representations showing a procedure for forming through-holes through a green sheet using a machining apparatus according to a first exemplary embodiment of the invention and FIG. 2 is a section view of a main part of a through-hole perforating step in the first exemplary embodiment.
The through-hole machining apparatus shown in FIGS. 1 and 2 forms through-holes 2 through a ceramic green sheet 1 and is mainly composed of a lower base 3 that corresponds to a punch, a releasing plate 4 made of a metal thin plate such as stainless steel, an upper base 5 that corresponds to a die and a pressurizing roller 7 attached with an adhesive layer 6 around an outer peripheral surface thereof. The lower base 3 is provided with projections 3b for perforating through-holes at a plurality of spots on an upper face 3a thereof, except on outer edges thereof. The releasing plate 4 is provided with clearance holes 4a at a plurality of spots corresponding to the group of projections 3b. The releasing plate 4 is removably set on the upper face 3a of the lower base 3 in a state in which the corresponding projections 3b are inserted into the clearance holes 4a. The upper base 5 is provided with a plurality of transmission holes 5a for inserting the group of projections 3b of the lower base 3. The pressurizing roller 7 is used to press the upper base 5 toward the releasing plate 4 in a state in which the green sheet 1 is set on the lower base 3.
A procedure for forming the through-holes 2 through the green sheet 1 by using the machining apparatus constructed as described above will be explained. At first, the releasing plate 4 is set on the upper face 3a of the lower base 3 while aligning the group of clearance holes 4a with the group of projections 3b as shown in FIG. 1A (releasing plate setting step). Next, the green sheet 1 is interposed between the lower base 3 and the upper base 5 by aligning and setting the green sheet 1 and the upper base 5 sequentially on the lower base 3 as shown in FIG. 1B (green sheet sandwiching step). Next, the upper base 5 is pressed by the pressurizing roller 7 so as to press the green sheet 1 down toward the releasing plate 4 to punch the green sheet 1 by the projections 3b and to perforate the through-holes 2 as shown in FIG. 1C (through-hole perforating step). Because a punched chip 1a of the green sheet 1 punched by the projections 3b is pushed into the transmission hole 5a of the upper base 5 at this time as shown in FIG. 2, the punched chip 1a may be removed by the adhesive layer 6 attached around the outer peripheral surface of the pressurizing roller 7. Then, after evacuating the upper base 5 from the lower base 3, the green sheet 1 is removed from the lower base 3 together with the releasing plate 4 by lifting up the releasing plate 4 from its corner as shown in FIG. 1D (green sheet releasing step).
Thus, according to this exemplary embodiment, the through-holes 2 are perforated through the green sheet 1 by the machining apparatus in which the releasing plate 4 is removably set on the upper face 3a of the lower base 3 and the green sheet 1 is set on the releasing plate 4 as shown in FIG. 2 that shows a state in which the through-hole is just perforated, so that the green sheet 1 whose rigidity is poor may be removed from the lower base 3 while setting the green sheet 1 on the releasing plate 4 made of a metal thin plate. That is, the green sheet 1 may be pulled out of the group of projections 3b of the lower base 3 while being stably held by the releasing plate 4 in the aforementioned green sheet releasing step, so that the projections 3b are unlikely to interfere with the green sheet 1 in pulling out the green sheet 1 and the removal of the green sheet 1 from the lower base 3 may be readily carried out without causing undesirable deformation such as elongation. Thus, it becomes possible to effectively prevent the positional precision of the through-holes 2 from deteriorating after the perforation. Moreover, because the green sheet 1 thus removed from the lower base 3 may be conveyed to a next step while being set on the releasing plate 4, there is also almost no such possibility that the green sheet 1 is deformed during its conveyance.
FIG. 3 is a pictorial representation of the step for sandwiching the green sheet of the machining apparatus according to a second exemplary embodiment of the invention and FIG. 4 is a pictorial representation of the through-hole perforating step in the second exemplary embodiment. Parts therein corresponding to those in FIGS. 1 and 2 will be denoted by the same reference numerals to avoid overlapped explanation.
The through-hole machining apparatus shown in FIGS. 3 and 4 is different from that shown in the aforementioned first exemplary embodiment in that an electromagnet 12 is disposed under the lower base 3 and that the releasing plate 4 and the upper base 5 are made of a ferromagnetic material such as nickel or iron. The electromagnet 12 is a coil wound around a core that generates magnetic force when the coil is energized. The releasing plate 4 is made of a nickel thin plate whose thickness is around 30 μm for example and is provided with the clearance holes 4a at a plurality of spots corresponding to the group of projections 3b of the lower base 3 in the same manner as the first exemplary embodiment. The upper base 5 is made of a nickel thin plate whose thickness is around 50 μm for example and is provided with the plurality of transmission holes 5a for inserting the group of projections 3b of the lower base 3 in the same manner as the first exemplary embodiment.
A through-hole machining method of the present exemplary embodiment is basically the same as the first exemplary embodiment explained with reference to FIG. 1, except that a releasing plate adsorbing step is added between the releasing plate setting step and the green sheet sandwiching step. That is, the releasing plate 4 is set on the upper face 3a of the lower base 3 while aligning the group of clearance hole 4a with the group of projections 3b at first as shown in FIG. 1A (releasing plate attaching step). At this time, the coil of the electromagnet 12 is not energized, so that the releasing plate 4 may be set readily on the upper face 3a of the lower base 3. Next, the coil of the electromagnet 12 is energized to generate magnetic force and to closely contact the releasing plate 4 with the upper face of the lower base 3 by means of the magnetic force (releasing plate adsorbing step). Thereby, wrinkles that might be generated in the thin releasing plate 4 are flattened and the releasing plate 4 becomes flat in conformity with the upper face of the lower base 3. Next, the green sheet 1 is interposed between the lower base 3 and the upper base 5 by aligning and setting the green sheet 1 and the upper base 5 sequentially on the lower base 3 as shown in FIGS. 1B and 3 (green sheet sandwiching step). The coil of the electromagnet 12 is energized also at this time, so that the upper base 5 is attracted to the upper face of the lower base 3 by the magnetic force of the electromagnet 12 via the green sheet 1 and the releasing plate 4. Next, the upper base 5 is pressed by the pressurizing roller 7 to press the green sheet 1 down toward the releasing plate 4 to punch the green sheet 1 by the projections 3b and to perforate the through-holes 2 as shown in FIG. 1C and FIG. 4 (through-hole perforating step). Because the punched chip 1a of the green sheet 1 punched by the projections 3b is pushed into the transmission hole 5a of the upper base 5 at this time as shown in FIG. 2, the punched chip 1a may be removed by the adhesive layer 6 attached around the outer peripheral surface of the pressurizing roller 7. Then, the upper base 5 is evacuated from the lower base 3 after de-energizing the coil of the electromagnet 12 and finally, the green sheet 1 is removed from the lower base 3 together with the releasing plate 4 by lifting up the releasing plate 4 from its corner as shown in FIG. 1D (green sheet releasing step).
Thus, according to the exemplary embodiment, the releasing plate adsorbing step is added between the releasing plate attaching step and the green sheet sandwiching step so that the releasing plate 4 closely contacts the upper face of the lower base 3 by the magnetic force generated by the electromagnet 12, so that even if the releasing plate 4 wrinkles in the releasing plate attaching step and is wavy, the wrinkles are flattened in the releasing plate adsorbing step and the releasing plate 4 becomes flat. Then, the green sheet 1 may be set flat on the releasing plate 4 in the green sheet sandwiching step. Moreover, because the upper base 5 is attracted to the upper face of the lower base 3 by the magnetic force of the electromagnet 12 via the green sheet 1 and the releasing plate 4 in the through-hole perforating step, the three parts of the releasing plate 4, the green sheet 1 and the upper base 5 will not be misaligned with respect to the lower base 3, allowing the positional precision of the through-holes 2 after the perforation to be markedly improved.
FIGS. 5A through 5C as well as FIGS. 6A through 6C are pictorial stepwise representations showing a procedure for forming through-holes through a green sheet by a machining apparatus of a third exemplary embodiment of the invention and FIG. 7 is a section view of a main part of the lower base of the third exemplary embodiment. Parts therein corresponding to those in FIGS. 1 and 2 will be denoted by the same reference numerals to avoid overlapped explanation.
The through-hole machining apparatus shown in FIGS. 5 through 7 is markedly different from that of the aforementioned first exemplary embodiment in that a releasing layer 8 made of an elastic member such as urethane foam is laid on the upper face 3a of the lower base 3. This releasing layer 8 is laid in a region that does not include the group of projections 3b of the upper face 3a of the lower base 3 and a gap 9 is created between each projection 3b and the releasing layer 8. Moreover, work efficiency and reliability are improved in the present exemplary embodiment by using a frame 10 attached to the lower base 3 so as to surround the green sheet 1, together with an adhesive sheet 11 pasted to the green sheet 1 and the frame 10.
A procedure of a through-hole machining method of the present exemplary embodiment will be explained. At first, the releasing layer 8 is laid in the region except of the group of projections 3b of the upper face 3a of the lower base 3 by means of coating of urethane foam as shown in FIG. 5A (releasing layer laying step). Next, the green sheet 1 is interposed between the lower base 3 and the upper base 5 by aligning and setting the green sheet 1 and the upper base 5 sequentially on the lower base 3 as shown in FIG. 5B (green sheet sandwiching step). Next, the upper base 5 is pressed by the pressurizing roller 7 to press the green sheet 1 down toward the releasing layer 8 to punch the green sheet 1 by the projections 3b and to perforate the through-holes 2 as shown in FIG. 5C (through-hole perforating step). At this time, punched chips of the green sheet 1 punched by the projections 3b are removed by the adhesive layer 6 attached around the outer peripheral surface of the pressurizing roller 7. Then, after evacuating the upper base 5 from the lower base 3, the frame 10 is attached to the lower base 3 so as to surround the green sheet 1 as shown in FIG. 6A (frame attaching step). Next, the adhesive sheet 11 for covering the upper face of the green sheet 1 is pasted to the green sheet 1 and the frame 10 as shown in FIG. 6B (adhesive sheet pasting step). After that, the green sheet 1 is removed from the lower base 3 together with the green sheet 19 and the adhesive sheet 11 as shown in FIG. 6C (green sheet releasing step).
Thus, the present exemplary embodiment is arranged such that the green sheet 1 is pushed up by elasticity of the releasing layer 8 when the pressure in the through-hole perforating step is removed by laying the releasing layer 8 made of an elastic member in advance on the upper face 3a of the lower base 3, so that a degree of insertion of the projections 3b into the through-holes 2 is remarkably reduced after the perforation. Therefore, there is almost no possibility that the projections 3b interfere with the green sheet 1 in the green sheet releasing step and it becomes possible to readily carry out the work for taking the green sheet 1 out of the lower base 3 without causing undesirable deformation such as elongation. Still more, because the frame 10 can hold the green sheet 1 to which the adhesive sheet 11 is pasted, the work efficiency in the green sheet releasing step is remarkably improved, thus effectively preventing the positional precision of the through-holes 2 from deteriorating after the perforation. Still more, because the upper face of the green sheet 1 through which the through-holes 2 have been perforated is covered by the adhesive sheet 11, it is possible to suppress the green sheet 1 from contracting due to natural drying, improving the effect of preventing the positional precision of the through-holes 2 from deteriorating also in this point. Still more, the green sheet 1 removed from the lower base 3 is conveyed to a next step while being held by the frame 10, there is almost no possibility of deforming the green sheet 1 during its conveyance.
It is noted that although the case of using the frame 10 together with the adhesive sheet 11 has been explained in the third exemplary embodiment, it is possible to prevent the deterioration of the positional precision of the through-holes 2 after the perforation without using the both. That is, because the green sheet 1 is pushed up by the elasticity of the releasing layer 8 after the through-hole perforating step and the degree of insertion of the projections 3b into the through-holes 2 is remarkably reduced, undesirable deformation such as elongation hardly occurs even if the green sheet 1 is peeled out of the lower base 3 as it is in the green sheet releasing step.
FIG. 8 is a pictorial representation for explaining the lower base provided for the machining apparatus according to a forth exemplary embodiment of the invention and FIG. 9 is a section view of a main part of the lower base. Parts therein corresponding to those in FIGS. 1 and 2 will be denoted by the same reference numerals to avoid overlapped explanation.
The lower base 3 of the through-hole machining apparatus shown in FIGS. 8 and 9 is composed of a die thin plate 13 provided with the group of projections 3b for perforating through-holes and an adsorption bed 15 on which a supporting flat plate 14 is set and is arranged so that the die thin plate 13 is supported on the supporting flat plate 14. The die thin plate 13 is what is formed by an additive method using electroless plating such as nickel plating and is provided with the group of projections 3b of about 150 μm in height from the upper face 3a of the base part of about 30 μm in thickness for example. The die thin plate 13 is attached to the frame 16 by its periphery while tensioning the die thin plate 13, so that the die thin plate 13 may be carried readily by the frame 16. The supporting flat plate 14 is made of a porous material such as stainless steel whose upper face is mirror-finished. The adsorption bed 15 is provided with a plurality of columns 15a erecting within that and the supporting flat plate 14 is set horizontally on the columns 15a. A suction valve 15b is attached on one side of the adsorption bed 15 so that air within the adsorption bed 15 is suctioned through the suction valve 15b.
When the air within the adsorption bed 15 is suctioned through the suction valve 15b after setting the die thin plate 13 on the supporting flat plate 14 by utilizing the frame 16 in the lower base 3 of the present exemplary embodiment, the suction force from the adsorption bed 15 acts evenly on the whole back face of the die thin plate 13 through the porous supporting flat plate 14, so that the die thin plate 13 may be closely contacted with the upper face of the mirror-finished supporting flat plate 14. Accordingly, when the group of projections 3b whose radial dimension is small is formed on the die thin plate 13 in high precision by the additive method, the plane precision may be remarkably improved by closely contacting the die thin plate 13 on the upper face of the supporting flat plate 14.
The lower base 3 thus constructed is applicable to any of the through-hole machining apparatuses of the first through third exemplary embodiments. When it is applied to the through-hole machining apparatus of the first exemplary embodiment, the die thin plate 13 is adsorbed to the supporting flat plate 14 by operating the adsorption bed 15 so as to suction air and the whole steps from the releasing plate attaching step through the green sheet releasing step may be carried out while keeping this state. Then, when the suctioning operation of the adsorption bed 15 is stopped after finishing the whole process, the operation of adsorbing the die thin plate 13 to the supporting flat plate 14 is released, so that the die thin plate 13 may be readily removed from the supporting flat plate 14 by utilizing the frame 16.
Patent Application
20070240814
