JP5011784B2 - Printing plate and printing method using the same - Google Patents

Description

  The present invention relates to a printing plate used in the manufacture of a double-sided or multilayer substrate in which a plurality of layers of circuit patterns are connected by inner via holes with a conductive paste, and a printing method using the same.

  In recent years, with the miniaturization and high density of electronic devices, there has been a strong demand for multilayer substrates not only for industrial use but also for consumer use.

  In particular, as the density of a multilayer substrate increases, circuit patterns become finer, and it is desired to reduce the thickness of the substrate together with a plurality of circuit patterns.

  In such a circuit board, it is indispensable to newly develop a connection method for connecting inner via holes between circuit patterns of a plurality of layers and a highly reliable structure. Proposed high density circuit board manufacturing methods have been proposed.

  Here, a method for manufacturing a double-sided substrate serving as a base for inner via hole connection using a conductive paste and a paste filling method will be described.

  9 (a) to 9 (f) are process cross-sectional views of a conventional method for manufacturing a double-sided circuit board, and FIG. 10 is a perspective view showing a plate frame to which a mask having an opening of a conventional example is attached.

  FIGS. 11A to 11D are process cross-sectional views of filling a conductive paste by a squeezing method.

  In FIG. 9, 21 is a prepreg sheet having a size of 300 mm × 300 mm and a thickness of about 100 μm. For example, a base material made of a composite material in which a wholly aromatic polyamide fiber of a nonwoven fabric is impregnated with a thermosetting epoxy resin is used. Mask films 22a and 22b made of a plastic film having a thickness of about 16 μm and a width of 300 mm, for example, polyethylene terephthalate, having a thickness of 0.01 μm or less and having a Si-based release layer formed thereon are bonded to the front and back surfaces of 21.

  For the bonding of the mask films 22a and 22b to the prepreg sheet 21, there has been proposed a method (Japanese Patent Laid-Open No. 7-106760) in which the resin components of the prepreg sheet 21 are melted using a laminating apparatus and the mask films 22a and 22b are continuously bonded. ing.

  Reference numeral 23 denotes a through-hole, which is a conductive paste made of conductive particles such as copper and epoxy resin electrically connected to metal foils 25a and 25b having a thickness of 18 μm and attached to both surfaces of the prepreg sheet 21. 24 is filled.

  As shown in FIG. 9 (a), first, the double-sided circuit board is manufactured by laser processing as shown in FIG. 9 (b) at a predetermined portion of the prepreg sheet 21 having the mask films 22a and 22b bonded to both sides. The through hole 23 is formed using a method or the like.

  Next, as shown in FIG. 9C, the through-hole 23 is filled with the conductive paste 24. As a method of filling the conductive paste 24, a prepreg sheet 21 having a through-hole 23 is set on a stage of a general printing machine (not shown), and reciprocating is performed using two squeegees such as urethane rubber alternately. By doing so, the conductive paste 24 is directly filled from above the mask film 22a.

  At this time, the mask films 22a and 22b on the upper surface play a role of a printing mask and a role of preventing contamination of the surface of the prepreg sheet 21a.

  A filling method of the conductive paste 24 will be described with reference to FIGS. 10 and 11A to 11D.

  Although the squeezing method is used for filling the conductive paste 24, the prepreg sheet 21 is provided with dedicated mask films 22a and 22b. Therefore, as shown in FIG. The plate frame 1 is made of stainless steel having a thickness of about 3 mm and has an opening 4 of 260 mm × 260 mm provided with an inclination of about 15 ° in the squeegee advance direction to facilitate passage of the squeegee, and orthogonal to the squeegee advance direction. A mask 2 is attached in which the width of about 10 mm of the openings 4 on both sides is set to a thickness (thin) that does not cause pressure loss during paste filling.

  First, as shown in FIG. 11 (a), the conductive paste 24 is filled with mask films 22a and 22b bonded to both sides placed on the stage 6 of a printing press (not shown) to form through holes 23. The mask 2 is set on the prepreg sheet 21, and only the forward squeegee 5a of the forward squeegee 5a and the backward squeegee 5b, which can be moved and pressed vertically and horizontally, is provided at a predetermined position on the mask 2. The conductive paste 24 is advanced while being lowered and rolled by applying pressure. The material of the squeegees 5a and 5b is a general squeegee rubber such as urethane.

  11B, the forward squeegee 5a passes through the inclined portion of the mask 2 and the prepreg sheet 21, stops again at a fixed position of the mask 2 on the opposite side, and then is raised to raise the conductive paste 24. Is falling naturally.

  Next, as shown in FIG. 11 (d), only the return-side squeegee 5 b is lowered onto the mask 2 to a predetermined position.

  After that, as shown in FIGS. 11C to 11D, the return squeegee 5b is passed over the mask 2 and the prepreg sheet 21 in the same manner as the forward squeegee 5a, so that the conductive paste 24 can be applied to the through holes 23. Filling is complete.

  Next, as shown in FIG. 9 (d), the mask films 22 a and 22 b are peeled from both surfaces of the prepreg sheet 21.

  Then, as shown in FIG. 9 (e), metal foils 25a and 25b such as copper are superimposed on both surfaces of the prepreg sheet 21, and in this state, heat pressing is performed with a hot press, and as shown in FIG. 9 (f). As described above, the thickness (t1 = about 100 is compressed (t2 = about 80 μm) of the prepreg sheet 21 and the prepreg sheet 21 and the metal foils 25a and 25b are bonded, and the metal foils 25 on both sides are provided at predetermined positions. The through holes 23 are electrically connected by a conductive paste 24 filled.

  Then, the metal patterns 25a and 25b on both sides are selectively etched to form a circuit pattern (not shown) to obtain a double-sided circuit board.

For example, Patent Document 1 and Patent Document 2 are known as prior art document information related to the invention of this application.
JP-A-6-268345 JP-A-7-106760

  The present inventor has found the following problems in the paste filling method of the above-described conventional circuit board manufacturing method.

  That is, when filling the paste by reciprocating the squeegee, the squeegee becomes longer than the size of the plate frame and cannot be lowered due to contact with the plate frame. Therefore, the squeegee is cut and used about 1 mm shorter than the size of the plate frame. However, a rubber material such as urethane changes in millimeters depending on the temperature and humidity of cutting and storage.

  In general screen printing, since about 1/3 of the screen width is the printing range of the product, there is no problem even if the squeegee length changes slightly.

  However, in the conductive paste filling method of this circuit board manufacturing method, as shown in FIG. 12, the conductive paste 24 remaining in the gap 8 between the plate frame 1 and the squeegee 5a or 5b is a mask having a width of only 10 mm. 2 will remain.

  When the gap 8 is small, the remaining conductive paste 24 is also reduced, so there is no problem. However, when the gap 8 exceeds a certain value, the conductive paste filling is completed, and as shown in FIG. The conductive paste 24 on the mask 2 flows out and falls on the stage 6.

  The conductive paste dropping phenomenon is more likely to drop as the conductive paste 24 has a dilatant property such that the viscosity decreases when the flow becomes small (static state).

  When the next prepreg sheet 21 is set on the stage 6 on which the conductive paste 24 has been dropped and the conductive paste 24 is filled, the conductive paste dropped on the stage 6 when the prepreg sheet 21 is taken out from the stage 6. The present inventor has grasped the problem that the conductive paste 24 in the through hole with the prepreg sheet 21 is pulled out to 24 and the conductive paste 24 disappears and disconnection occurs.

  In order to achieve the above object, the paste printing / filling method of the present invention provides a high-quality circuit board with stable connection resistance by absorbing gap variations between both sides perpendicular to the squeegee advance direction and the plate frame. It is for the purpose.

  The invention according to claim 1 of the present invention provides a printing plate in which a mask having an opening is fixed to a plate frame of at least four sides, and a gap absorbing portion is provided on the plate frame on both sides in the squeegee traveling direction, and the gap absorbing portion Is a printing plate characterized by having a flat portion that is a contact surface with both ends of the squeegee and an inclined portion at the squeegee entry portion. By providing a gap absorbing portion in the squeegee advancing direction of the plate frame, the paste After filling, it is possible to reduce the amount of paste remaining on the mask in the squeegee traveling direction of the plate frame, thereby providing a plate that can prevent the paste from dropping on the contact surface with the squeegee on the stage of the printing press.

  Further, the gap absorbing portion provides a printing method that can smoothly contact, deform, and slide both ends of the squeegee to the gap absorbing portion by using a printing plate having a flat portion and an inclined portion. .

  The invention according to claim 2 of the present invention is such that the gap absorbing portion does not come into contact with the lowest point of the squeegee when the squeegee is raised, and the height of the paste that has entered does not leak from the gap absorbing portion. This is a printing plate that supports printing using the forward and reverse squeegees, and part of the other squeegee where one squeegee rises and moves during paste filling due to the appropriate height of the gap absorber. By providing a printing plate that prevents contact with the gap absorbing portion and prevents the paste to be used from leaking from the gap absorbing portion onto the mask of the plate frame, paste filling can be performed smoothly.

  The invention described in claim 3 of the present invention is the printing plate according to claim 1, wherein the surface smoothness of the gap absorbing portion is equal to or greater than the surface smoothness of the mask, and the sliding of the squeegee is easy. And has the effect of preventing wear.

  Invention of Claim 4 of this invention is a method of printing a paste on a to-be-printed material using the printing plate of Claim 1, Comprising: The both ends of a squeegee are deformed at the time of printing, It is a printing method characterized by absorbing the gap, and can smoothly contact, deform and slide both ends of the squeegee to the gap absorbing portion. Reduces the amount of paste remaining on the mask in the direction of travel, prevents the paste from dropping on the contact surface with the squeegee on the printing press stage, and absorbs gap variations between the sides of the printing frame and the sides perpendicular to the direction of travel of the squeegee By doing so, a high-quality circuit board with stable connection resistance can be provided.

  The invention according to claim 5 of the present invention is the printing method according to claim 4, wherein the squeegee is brought into contact with and deformed in the gap absorbing portion, and the squeegee is brought into contact with the gap absorbing portion. During printing, both ends of the squeegee can be easily deformed.

  Invention of Claim 6 of this invention is a printing method of Claim 4 which provided the deformation | transformation absorption part in a part of both ends of a squeegee, The load at the time of a squeegee approaching a clearance gap absorption part is provided. It is possible to reduce the deformation of the squeegee and the pressure attenuation when the squeegee proceeds.

  The invention according to claim 7 of the present invention is the printing method according to claim 4, wherein a part of the squeegee in the thickness direction is thinned to form a deformation absorbing portion, and the gap absorption due to the thick squeegee is obtained. The present invention provides a printing method that reduces the load when entering the part and does not cause any trouble in the filling pressure of the paste in the through hole.

  The invention according to claim 8 of the present invention is the printing method according to claim 4 in which the paste has a Newtonian or dilatant property, and particularly the dilatant property and the viscosity in which the viscosity decreases when the paste kneading is stopped. The effect when using a Newtonian paste that does not rise is great.

  The invention according to claim 9 of the present invention is characterized in that a substrate to be printed has a mask film bonded to both sides of a substrate and through holes are formed, and printing fills the through holes with a paste. According to a fourth aspect of the present invention, even when a low-viscosity paste used for paste filling printing in the through holes is used, the paste does not fall on the through holes of the printing material. Thereby, it has the effect | action that the problem that the electrically conductive paste in the through-hole of a prepreg sheet is pulled out by the electrically conductive paste which fell on the stage, or the bad influence at the time of peeling a mask film is eliminated.

  Invention of Claim 10 of this invention is a printing method of Claim 4 using the paste comprised with the metal powder, the thermosetting resin, and the hardening | curing agent, The paste to a through-hole Even when a low-viscosity paste such as a conductive paste containing a metal powder used for filling printing is used, it has the effect of eliminating the possibility of adversely affecting the paste quality.

  As described above, the paste filling method of the present invention is excellent in quality by providing a gap absorbing portion with a squeegee on the plate frame to reduce the paste remaining on the mask, thereby preventing the paste from dropping onto the stage. A circuit board can be realized.

(Embodiment)
The process cross-sectional view of the method for manufacturing a double-sided circuit board is the same as the conventional method, and the description thereof will be omitted. The paste filling method and the filling plate will be described.

  FIG. 1 is a perspective view of the plate of the present invention, and FIG. 2 is a plan view. FIG. 3 is a sectional view for explaining the height of the gap absorbing portion of the plate of the present invention, and FIGS. 4A to 4D are sectional views of the paste filling process by the squeezing method of the present invention. FIG. 5 is a partial cross-sectional view of the present invention when the paste is filled.

  In the present embodiment, a dedicated mask film is bonded to a prepreg sheet (300 × 300 mm, thickness of about 100 μm) filled with a conductive paste using a laminator to form a through hole.

  For this reason, as shown in FIGS. 1 and 2, the plate frame 1 of the filling plate 10 is made of stainless steel having a thickness of about 3 mm and has an inclination of about 15 ° in the squeegee traveling direction in order to facilitate the passage of the squeegee. A mask 2 having an opening 4 of 260 mm × 260 mm provided and having a width (thin) that does not cause a pressure loss at the time of paste filling is attached to about 10 mm width of the opening 4 on both sides orthogonal to the squeegee traveling direction. Yes.

  Furthermore, the gap | interval absorption part 3 is attached with the adhesive agent on the both sides of the squeegee advance direction of the plate frame 1. FIG.

  In the present embodiment, the thickness of the gap absorbing portion 3 is set to 0.7 mm, respectively, and as shown in FIG. 2, from the vicinity of the conductive paste filling start lowering of the forward squeegee 5a to the vicinity of the charging downward position of the backward squeegee 5b, Inclined portions 3b are provided in the squeegees 5a and 5b entering portions on both sides of the absorbing portion 3 for the purpose of preventing squeegee damage and wear.

  As shown in FIG. 3, the height of the gap absorbing portion 3 is the lowest of the squeegee that moves up and moves so that the squeegee that moves up and move (in FIG. 3, the return side squeegee 5 b) does not contact the gap absorbing portion 3. It is preferable that the height is lower than the point and the conductive paste being filled does not leak.

  In the present embodiment, the gap absorbing portion 3 is made of a stainless steel plate and pasted on the plate frame 1, but the material may be another metal material or resin material, or may be formed directly on the plate frame 1 body. good.

  Further, the flat portion 3a and the inclined portion 3b which are contact surfaces with both ends of the squeegee of the gap absorbing portion 3 are buffed to prevent wear of the squeegee (generation of dust), and the surface smoothness of the mask 2 is smoothed. Equal to or better than sex.

  A method of filling the conductive paste using the filling plate 10 will be described with reference to FIGS.

  The conductive paste 24 used at this time was copper powder having an average particle diameter of 2 μm, and the resin was a thermosetting epoxy resin (solvent-free type) and an amine curing agent of 85% by weight, 12.5% by weight, The conductive paste 24 is sufficiently kneaded with three rolls so as to be 2.5% by weight, and the conductive paste 24 has a dilatant property in which the viscosity increases when the rotational speed is increased during the viscosity measurement. The viscosity is about 50 Pa · s at a rotation speed of 0.5 rpm with an E-type viscometer.

  First, as shown in FIG. 4A, the conductive paste 24 is filled by adhering a mask film on both surfaces placed on a stage 6 having a function of suction and fixing of a printing machine (not shown). The mask 2 is set on the prepreg sheet 21 on which is formed.

  Then, only the forward squeegee 5a of the forward squeegee 5a and the backward squeegee 5b which are movable and pressurized vertically and horizontally provided above is lowered to a predetermined position on the mask 2, and a pressure of 0.1 MPa is applied. The conductive paste 24 is advanced while rolling at a speed of 50 mm / s.

  Air is used to pressurize the squeegee 5a. Immediately after the squeegee 5a moves forward, the squeegee 5a contacts and enters the gap absorbing portion 3 shown in FIGS.

  In the present embodiment, in order to make the gap between the squeegee 5a and the gap absorbing portion 3 zero, a length longer than the dimension between the gap absorbing portions 3 is used.

  Since the gap absorbing portion 3 corresponds to the inside of the conventional plate frame (a part of the plate frame), the plate in the conventional example has a squeegee length that cannot be used by contacting a part of the plate frame when lowered.

  FIG. 5 shows a partial sectional view of the squeegee 5a in contact with the gap absorbing portion 3. Although there is a gap 8 between the plate frame 1 and the squeegee 5a, the squeegee 5a is longer than the gap absorbing portion 3, and the gap There is no gap 8 between the absorber 3.

  In this state, the squeegee 5a enters the gap absorbing portion 3. By designing the forward squeegee 5a to be longer than the squeegee holder 7, when the squeegee 5a enters the gap absorbing portion 3, as shown in FIG. A part of the squeegee 5a can be deformed to allow passage.

  If the forward squeegee 5a is thick and a load is applied to the gap absorbing portion 3 to cause trouble in the filling pressure, a part of both ends of the forward squeegee 5a is processed as shown in FIG. By providing the deformation absorbing portion 13, the deformation of the squeegee and the pressure attenuation when the squeegee proceeds can be reduced.

  There is no restriction | limiting in the shape of the deformation | transformation absorption part 13 of a squeegee, What is necessary is just to make thin except the ridgeline which contacts the base material at the thickness direction of both ends of a squeegee.

  Here, the forward squeegee 5a has been described as an example, but it goes without saying that the same applies to the backward squeegee 5b.

  Next, as shown in FIG. 4B, the forward squeegee 5a is passed through the inclined portion of the mask 2 and the prepreg sheet 21, stopped again at the fixed position of the mask 2 on the opposite side, and then raised to be conductive paste. Let 24 fall naturally.

  Then, as shown in FIG. 4 (c), only the backward squeegee 5 b is lowered to a predetermined position on the mask 2.

  Thereafter, as shown in FIG. 4 (d), similarly to the forward squeegee 5a, the return squeegee 5b is passed over the mask 2 and the prepreg sheet 21 through a gap absorbing portion (not shown), thereby allowing the through hole 23 to pass. The filling of the conductive paste 24 into is completed.

  As a result of filling the conductive paste with the plate in the present embodiment, as shown in FIG. 8, the conductive material is not formed on the mask 2 having a width of about 10 mm in the direction orthogonal to the squeegee traveling direction after passing through the squeegees 5a and 5b. It was confirmed that almost no paste 24 remained and even the conductive paste 24 having dilatant properties did not fall on the stage 6.

  In the embodiment, the squeegee is made longer than the gap absorbing portion. However, if the squeegee is shorter, the squeegee can be used up to the same level as the conventional example, and can absorb up to the sum of the two gap absorbing portions (1.4 mm in the embodiment). .

  Moreover, although the thickness of the gap absorbing portion is 0.7 mm, it may be set to a thickness that does not cause quality problems such as filling pressure and squeegee wear.

  Although the dilatant conductive paste is used in the embodiment, the conductive paste is used in the case where the gap between the plate frame and the squeegee is large even when the paste kneading is stopped and the viscosity is not increased even when the paste kneading is stopped. It is needless to say that the conductive paste dropping prevention measure of the present invention is effective.

  Moreover, although it was set as the filling method of the conductive paste to the base material used for a two-layer circuit board in embodiment, the conductive paste fall prevention measure of this invention to the conductive paste filling to the base material used for a multilayer board | substrate Can be easily estimated.

  Moreover, although the copper conductive paste is used in the embodiment, it is possible to use a conductive paste mainly composed of silver, gold, and an alloy powder or solder thereof, or a conductive paste mainly composed of a polymer material. If the conductive paste is filled into the base material on which the mask film is disposed, it can be easily estimated that the conductive paste dropping prevention measure of the present invention is effective.

  As described above, the paste filling method according to the present invention eliminates the drop of the paste onto the stage when filling the paste and stabilizes the connection quality. In general, the circuit board having the inner via hole connection with the conductive paste is used. It is useful, and it can be said that the industrial applicability of the present invention is great.

Perspective view of the plate of the present invention Plan view of the plate of the present invention Explanatory drawing of the height of the gap absorbing portion of the plate of the present invention Process sectional view of paste filling by squeezing method of the present invention Sectional drawing of a partial position where the squeegee contacts the gap absorbing portion of the plate of the present invention The one part top view at the time of passing the clearance gap absorption part of the plate of the present invention through a squeegee One-part plan view of the squeegee deformation absorbing portion of the present invention Cross-sectional view of remaining paste after filling paste of the present invention Cross-sectional process diagram of conventional double-sided circuit board manufacturing method The perspective view which shows the plate frame which attached the mask which has the opening part of a prior art example. Cross-sectional view of paste filling process using conventional squeezing method Sectional drawing of a partial position where the squeegee contacts the gap absorbing part of the plate of the conventional example Cross-sectional view of paste dropping after filling paste of conventional example

DESCRIPTION OF SYMBOLS 1 Plate frame 2 Mask 3 Crevice absorption part 3a Flat part 3b Inclination part 4 Opening part 5a Outward squeegee 5b Return side squeegee 6 Stage 7 Squeegee holder 8 Crevice 10 Plate 21 Prepreg sheet 22a, 22b Mask film 23 Through-hole 24 Conductive paste 25a, 25b metal foil

Claims (10)

In a printing plate in which a mask having an opening is fixed to a plate frame of at least four sides, a gap absorbing portion is provided on both sides of the plate frame in the squeegee progression direction,
The printing plate according to claim 1, wherein the gap absorbing portion has a flat portion serving as a contact surface with both ends of the squeegee and an inclined portion at a squeegee entry portion. 2. The printing plate according to claim 1, wherein the gap absorbing portion does not come into contact with the lowest point of the squeegee when the squeegee is raised, and has a height at which the charged paste does not leak from the gap absorbing portion. The printing plate according to claim 1, wherein the surface smoothness of the gap absorbing portion is equal to or greater than the surface smoothness of the mask. A method for printing a paste on a substrate using the printing plate according to claim 1, wherein both ends of the squeegee are deformed during printing to absorb a gap with the plate frame. The printing method according to claim 4, wherein a squeegee is brought into contact with and deformed in the gap absorbing portion. The printing method according to claim 4, wherein a deformation absorbing portion is provided at a part of both ends of the squeegee. The printing method according to claim 4, wherein a part of the squeegee in the thickness direction is thinned to form a deformation absorbing portion. The printing method according to claim 4, wherein the paste has Newtonian or dilatant properties. The printing method according to claim 4, wherein the substrate is a substrate in which a mask film is pasted on both sides of the substrate and through holes are formed, and the printing fills the through holes with paste. The printing method of Claim 4 using the paste comprised with the metal powder, the thermosetting resin, and the hardening | curing agent.

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