JP5038840B2 - Paste-like material filling squeegee and paste-like material filling method - Google Patents

Description

The present invention is used in manufacturing the double-sided or multilayer circuit board used in various electronic apparatuses, pasty material filling squeegee to fill the pasty material into the via hole, relates 及 beauty pasty material filling method It is.

  In recent years, the density of multi-layered wiring boards has been increasing especially, and via holes for interlayer connection have been miniaturized, and conductive paste-like materials are used to fill conductive paste-like materials with conductive paste-like materials. In this case, the filling rate of the conductive paste in the via hole particularly affects the connection resistance value. That is, when the paste is sufficiently filled up to the substrate surface, the connection between the layers can be obtained, but when the paste is recessed from the substrate surface, the connection resistance between the layers becomes high. The smaller the via hole, the greater the influence of the filling rate on the connection resistance value.

  Under such a background, conventionally, after filling with a squeegee having a sharp corner or a small R-shape, the R-shape rounded to be larger than at least the corner in the filling operation. There has been proposed a squeegee and a paste filling method for filling a micro via hole with a conductive paste by scraping with a squeegee (see Patent Document 1).

  Also, a via printing method has been proposed in which a squeegee squeegee with a sharp squeegee tip is used, and the rubber squeegee surface contacting the squeeze squeegee and the paste material is inclined 30 to 40 degrees with respect to the printing mask (patent) Reference 2).

JP 2004-17374 A (summary column, FIG. 1) JP 2000-133934 A (paragraph 0013, FIG. 2)

  In the paste filling to the micro via hole disclosed in the above-mentioned Patent Document 1, the corner surface contacting the squeegee base material is rounded so that the paste surface in the via hole is not removed, so that the micro via hole is sufficient. The paste amount can be filled. However, for example, in filling a via hole formed in a green sheet as a base material with a diameter of about 100 to 200 μm, a dent in the via hole portion after filling does not require a plurality of printings. There are few, and the dent in the via hole part after filling becomes large.

  If the dent in the via hole after filling is large, it causes a connection failure of the wiring in the via hole, and if the number of times of printing is increased in order to realize a predetermined paste filling amount, the productivity is lowered. In addition, the increase in the number of times of printing has a problem that the paste rushes to the back surface of the mask, the via hole diameter increases (bleeds) in the printed pattern, and the print quality is deteriorated.

  In addition, the paste filling method disclosed in Patent Document 2 uses a sword squeegee as a squeegee, and promotes the rolling property of the paste by attaching the sword squeegee to the mask surface so as to improve the paste filling property. It is. However, in this method, the fillability is improved by tilting the squeegee with respect to the mask surface, but the pressure applied to the squeegee during printing (filling) is applied to the shape of the filled via hole. However, there is a problem that the squeegee is hardly inclined and the filled via hole shape varies. In addition, it is difficult to apply printing pressure (squeegee pressure) to suppress variation in shape, and in addition, the squeegee deforms due to squeegee pressure and fills the pattern shape (via hole diameter, via hole dent amount). There is a problem that variation occurs.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a paste-like material filling squeegee that uniformly fills a via hole formed in a substrate. .

Another object is to provide a paste-like material filling how to improve the stability of the paste filling quality of the via holes formed in the substrate.

The squeegee for filling paste-like material according to the present invention fills the paste-like material by applying a certain pressure to the mask when filling the via-hole formed in the base material via the mask. A paste-like material filling squeegee that is used to advance at a constant speed along the mask while extruding in a direction ,
The cross-sectional shape of the squeegee that is in contact with the mask is configured such that, when the squeegee axis is perpendicular to the mask, the angle formed with the mask is different from the left and right, and the squeegee axis is perpendicular to the mask. In this state, the angle formed between the surface on the side touching the paste-like material and the mask is a contact angle, and the angle between the surface on the side where the squeegee does not touch the paste-like material and the mask is the anti-contact angle. The contact angle is configured to be greater than the anti-contact angle, the squeegee tip angle of the squeegee is set to 110 degrees to 130 degrees, and the squeegee surface on the side of the squeegee that contacts the pasty material And the angle between the mask and the mask is set to 20 degrees to 40 degrees .

Further, in the paste material filling method according to another invention, when the cross-sectional shape of the paste material filling squeegee in contact with the mask is arranged with the squeegee axis perpendicular to the mask, the angle between the mask and the mask is different from right to left. The contact angle is an angle formed between the mask and the surface on the side in contact with the paste-like material with the squeegee axis perpendicular to the mask, and the squeegee becomes the paste-like material. When the angle formed between the non-contact side surface and the mask is the anti-contact angle, the contact angle is configured to be larger than the anti-contact angle.
The paste used by setting the squeegee tip angle to 110 degrees to 130 degrees and the angle between the squeegee surface of the squeegee contacting the paste-like material and the mask to 20 degrees to 40 degrees. With the squeegee for filling the material,
When filling the via hole formed in the substrate with the paste-like material through the mask, a constant pressure is applied to the mask to extrude the paste-like material in the filling direction, and then along the mask. A method of making it progress at a speed ,
It is characterized in that the filling and perpendicular to the axis of the squeegee towards the bottom to provide a certain gap between the mask from above the mask on the substrate.

  According to the paste material filling squeegee according to the present invention, the paste material can be uniformly filled in the via holes formed in the base material.

According to the pasty material filling how according to another invention, it is possible to improve the pasty material filling quality stability of the via holes formed in the substrate.

Hereinafter, pasty material filling squeegee according to the present invention, a preferred embodiment of 及 beauty pasty material filling method will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 shows a squeegee 1 according to the first embodiment. In this figure, the squeegee 1 is shown as a schematic view so that a portion where the squeegee 1 is in contact with the mask 2 can be seen. In the squeegee 1, when the squeegee shaft 3 is arranged perpendicular to the mask 2, the cross-sectional shape of the squeegee 1 is configured to have different left and right angles with respect to the mask 2 as shown in FIG. 1. As shown in FIG. 2, which will be described later, two squeegees 1 having this cross-sectional shape are arranged at a predetermined distance apart.

  As shown in FIG. 1, the angle formed between the mask 2 and the surface of the squeegee 1 in contact with the paste 4 (see FIG. 2) with the squeegee axis 3 perpendicular to the mask 2 is referred to as a contact angle. ) When the angle formed between the surface of the squeegee 1 not touching the paste 4 and the mask 2 is defined as φb (referred to as an anti-contact angle), the squeegee tip angle indicates {180− (φa + φb)} (degrees).

  The squeegee 1 used by the inventors for the experiment had a dimension (thickness) parallel to the printing direction of the squeegee 1 of 5 to 10 (mm), and the rubber hardness of the squeegee 1 was 70 ± 5 (degrees). In addition, the printing machine used is a system that has a function of observing and recognizing the alignment mark formed on the work with a plurality of CCD cameras and storing the position by placing the work on a vacuum suction, and setting the stage on a mask. A squeegee head and a squeegee head for mounting a squeegee with a drive system necessary for reciprocating to the specified position, a mechanism for raising and lowering the stage at the position where the mask is set, and a mechanism for applying a constant pressure. It is a facility with a drive system that reciprocates back and forth in a direction parallel to the printing direction.

  FIG. 2 is a diagram showing a squeegee operation during filling. FIG. 2A is a diagram showing the forward movement of the first and second squeegees 1a and 1b, and FIG. 2B is a diagram showing the return movement of the first and second squeegees 1a and 1b. From the rear side of the paste 4, the first squeegee 1a fixed to the holder 5a, which is the first support, descends to the mask 2 supported by the mask plate frame 6, and reaches a certain pressure (0.25 ± 0.05). (MPA)) is applied and proceeds at a constant speed of about 100 (mm / s) while extruding the paste 4 in the filling direction. During this time, the second squeegee 1b fixed to the holder 5b as the second support is not in contact with the mask 2.

  After moving a certain length beyond the pattern formation region, the first squeegee 1a that contributed to the filling rises, and the second squeegee 1b on the side that has not touched the mask 2 changes to the mask 2 The squeegee moves in the return direction at the same constant speed as the forward direction while applying the constant pressure of the same pressure value as the forward direction and pushing out the paste 4. Through these operations, the paste filling into the via hole (not shown) is completed.

  The paste 4 used for filling the via holes is a conductor paste containing 80 to 85% by weight of silver, and the paste viscosity measured with a Brookfield viscometer (rotation speed 10 (rpm)) is 350 to 450 ( Pa · s). The base material used for filling the via holes is a ceramic green sheet having a size of 200 mm in length and 200 mm in width, and the thickness of the ceramic layer is 50 to 100 (μm). The via hole opened in the substrate is a cylinder having a diameter of 100 to 200 (μm), the minimum interval (pitch) between the via holes is 300 to 400 (μm), and the number of via holes is 40,000 to 50. , 000.

  A squeegee with a different sword angle was prepared by fixing the contact angle φa to the green sheet and changing the anti-contact angle φb, and via filling printing was performed. The used mask 2 is a metal mask and has a plate thickness of 0.03 to 0.05 (mm).

  FIG. 3 shows an enlarged view of the squeegee sword tip when the filling direction is forward (here, the contact angle φa = 40 ° and the anti-contact angle φb = 20 °). A thin film-like sheet 8 of about several tens of μm is placed on a stage 7 of a printing machine, and the ceramic layer 9 of the ceramic green sheet and the carrier film layer 10 are placed thereon in order, and a fixed gap (0.5 ± 0 .25 (mm)), the hole 2a of the mask 2 and the via hole on the ceramic green sheet side are overlapped to fill the paste (the paste is not shown in FIG. 3). The reason why the thin film-like sheet 8 is placed on the stage 7 is to prevent the filled paste from remaining on the stage 7. The reason why the paste is filled from the side of the carrier film layer 10 is to prevent bleeding of the filling portion caused by the back of the mask 2 from being generated on the surface of the ceramic layer 9.

  The printing condition parameters are squeegee pressure, squeegee speed, and the gap (gap) between the mask surface and the workpiece surface during filling, but the basic conditions are set as follows in advance to fill the influence of the shape of the squeegee sword tip. The effect on the condition was investigated.

  Table 1 shows the state of the prepared squeegee sword tip, the angle formed by the squeegee axis 3 and the mask 2 is vertical, the attack angle is fixed at 40 ° and the sword angle is changed. The filling result was evaluated by measuring the filling diameter (average, standard deviation) and filling dent (average, standard deviation). The packing diameter in Table 1 indicates the standard value obtained by dividing the average of the pore diameters filled in the paste by the hole diameter previously made on the ceramic green sheet, and 3σ in the packing diameter column indicates the standard deviation of the packing diameter in advance. It is a value obtained by multiplying the value divided by the hole diameter opened on the ceramic green sheet by three.

  The filling diameter (standard value) is larger than 1 due to the overlap with the mask plate, but the closer to 1, the more ideal the filling state is considered. Actually, it is usually slightly larger than 1 due to the alignment accuracy with the mask plate. The smaller the filling dent average, the smaller the difference in height between the green sheet surface and the filling portion, but the smaller the filling dent variation (3σ), the more uniform the filling shape.

  In the filling state, since the filling amount to the desired via hole was confirmed by the number of times of printing twice, the sample was prepared by fixing the number of times of printing to two times (one reciprocation). As shown in FIG. 4, the filling diameter is a result of measuring the diameter 11 p of the via in a state where the via hole 11 is filled with the paste. The filling dent shows the result of measuring the height difference 12 of the paste filling part from the green sheet surface. As the measurement points, a plurality of points (30 to 60 points) were extracted from the entire region including the pattern region as a monitor.

<Squeegee tip angle and filling shape>
In Table 1, No. 1 to No. Sample 5 was prepared in order to investigate the influence of the anti-contact angle φb on the side where the squeegee does not contact the paste during filling. The average of the filling diameter is almost unchanged from 1.26 to 1.31 regardless of the magnitude of the anti-contact angle φb, but the change in the standard deviation σ of the filling diameter becomes small as the anti-contact angle φb decreases, and is slight. There is a trend of improvement. On the other hand, it can be seen that the filling dent rapidly decreases as the standard deviation σ decreases the anti-contact angle φb, and the variation is improved.

  Here, the filling recess is defined as a recess (a value in the negative direction in terms of the Z axis) with the green sheet surface as the height origin. For example, in the case of No. 1 and No. 2 samples, the filling dents may be 20 μm or more higher than the green sheet surface in the range of dent variation (average ± 3σ). That is, a level difference due to the paste rising in the filling portion occurs, and the level difference that cannot be covered by the next printing process (one-time printing) causes the disconnection of the wiring connection portion.

  On the other hand, in the case of the samples No. 3 to No. 5, even if the filling portion swells from the green sheet surface within the range of dent variation (average ± 3σ), the swell of the filling portion is allowed in the printing in the subsequent process. It is in the possible range. That is, it is suggested that the filling portion can be filled in a uniform state with little unevenness. This indicates that when the squeegee sword tip angle is larger than a certain angle, the filling state, particularly the dent value, is formed stably with little variation. The increase in the sword angle is considered to be a result of suppressing the deformation of the squeegee tip by improving the mechanical strength of the squeegee with respect to the squeegee pressure applied during printing.

  Here, the attack angle φa and the anti-contact angle φb include an error of ± 5 degrees with respect to the set value due to the processing accuracy of the polishing machine. However, in the case of the samples No. 1 to No. 5, it is considered that the anti-contact angle φb becomes zero with respect to the setting of 5 degrees. This is because the tip of the squeegee comes into contact with the mask surface at the surface, and an obstacle occurs in the squeegee operation, so that it cannot be used in the filling operation in this arrangement. Therefore, the effective setting angles of the attack angle φa and the anti-contact angle φb can only be set larger than 5 degrees. When the attack angle φa is 40 degrees, the sword tip angle is less than 135 degrees and is the maximum practical angle.

  If the squeegee tip angle range in which the filling dent does not become higher than the allowable range from the green sheet surface within the range of variation in the filling dent (average value −3σ to average value + 3σ) is considered as the appropriate range of the squeegee shape for filling, The blade tip angle is in the range of 110 to 130 degrees, and the filling state is in a stable range. More preferably, the filling state is stabilized in the range of 120 ° to 130 °.

<Attack angle and filling shape>
Samples No. 7 to No. 10 were examined for the influence of the attack angle on the filling shape, and the results are shown in Table 2. In both cases, the number of printings was fixed to 2 (one reciprocation). In the squeegee sword tip specification, the sword angle is constant (90 degrees), and the effect of the size of the sword angle on the filling property is removed.

  The deformation of the squeegee during printing corresponds to the most severe conditions (easy to deform). The packing diameter in Table 2 indicates the standard value obtained by dividing the average of the hole diameters filled in the paste by the hole diameters previously opened on the ceramic green sheet. In the column of packing diameter, 3σ indicates the standard deviation of the packing diameter in advance. It is a value obtained by multiplying the value divided by the hole diameter opened on the ceramic green sheet by three.

  As a result, it was confirmed that the filling state (filling diameter, filling dent) was not significantly changed in the range of an attack angle of 30 to 50 degrees and could be filled. In the case where the attack angle is smaller than 30 degrees, the No. 10 sample was filled with a mounting angle of 70 degrees, a contact angle of 40 degrees, and an anti-contact angle of 50 degrees (corresponding to an attack angle of 20 degrees). As a result, many of the pastes were not filled properly. In the column of sample No. 10 in Table 2, “−” means that calculation is impossible.

  Sample No. 6 shows the filling result when the attack angle is 70 degrees as a case where the attack angle is larger than 50 degrees. Compared with the filling state of sample No. 7 to No. 9, the filling state is not good. That is, when the filling diameter includes variation (filling diameter ± 3σ), the filling diameter may be smaller than 1. That is, it is suggested that insufficient filling occurs. Furthermore, the filling dent average is large, and the variation (3σ) of the filling dent is also large.

  In order to achieve a filling amount equivalent to that of samples No. 1 to No. 5 with the No. 6 sample, it was necessary to increase the number of printings to 4 or more. As a result of increasing the number of times of printing, the average filling diameter increased from 1.15 to 1.4, and bleeding at the time of filling increased by 5 to 13% as compared with the case of two times of printing. As a result, 3σ of the filling diameter was expanded. Table 3 shows the results of investigating the effect on the fillability of the attack angle by changing the size of the sword tip angle. The squeegee 1 was examined by using the squeegee 1 used in the experiment of Table 1 and using the anti-contact of Table 1 on the attack angle side, paying attention to the filling dent having a large change.

  From Table 3, it was found that the fluctuation of the filling dent 3σ was small even in the range of 20 to 40 degrees where the attack angle was small depending on the sword angle. This is a result suggesting that when the squeegee sword tip angle exceeds a certain value, the squeegee sword tip is difficult to deform and the filling state is stabilized.

  When the attack angle is less than 10 degrees, there is no data due to the restriction of the mounting angle that the squeegee operating range exceeds the printing range in the range of the sword angle of 100 to 130 degrees, but the attack angle of 20 degrees when the sword angle is 90 degrees. The result explains a phenomenon close to this. That is, it is presumed that the angle is smaller than the set 20 degrees due to the deformation of the sword tip, and the filling property (filling omission) deteriorates when the attack angle approaches zero, so that stable filling is possible at an attack angle of less than 10 degrees. Concluded that it was impossible.

  From the above results, the appropriate condition range of the attack angle using the squeegee and the squeegee arrangement according to the first embodiment is 20 degrees or more and 50 degrees or less, preferably 20 degrees or more and 40 degrees or less.

<Squeegee mounting angle and filling shape>
In order to investigate the change of the squeegee mounting angle and the filling state, the filling state was examined for the squeegee arrangement shown in FIG. In this squeegee sword tip, the squeegee sword tip according to the first embodiment is compared with the case in which the squeegee sword tip is inclined at a fixed attachment angle (90-ψ) and the vertical mounting case in the first embodiment. The purpose is to do. Samples No. 1 and No. 8 listed in Tables 1 and 2 correspond as examples. This is extracted in Table 4.

  Both squeegees have a sword tip angle of 90 degrees. As for the packing diameter, no difference was observed in the average and the variation (3σ). As for the filling dent, although the average is not different, a difference is confirmed in the variation (3σ). That is, the filling dent variation when the mounting angle is 90 ° is improved to half of the filling dent variation when the mounting angle is 80 °. The result suggests the superiority of 90 ° mounting with respect to the filling shape.

  With respect to the filling dent, when the squeegee 1 is tilted 10 degrees with the φb side as the attack angle side (mounting angle is 80 degrees), the filling dent standard deviation is ± 10% relative to the basic printing pressure condition value. It was constant. On the other hand, when the squeegee was vertically arranged and filled with the φa side as the attack angle side, the filling dent standard deviation was constant with respect to the condition variation of ± 20% with respect to the basic printing pressure condition value.

  From this, it is confirmed that the filling condition margin is doubled and the filling margin is expanded in the case where the squeegee is tilted and filled, and the filling condition margin is doubled and the filling margin is enlarged. The usefulness of was confirmed.

As described above, the pasty material filling squeegee according to the first embodiment, and according to the paste-like material filling how the relationship between the angle of the side which contacts the side of the angle and paste does not contact the paste sword squeegee Is effective in suppressing variation in shape after filling (filling diameter, dents in the filling portion) resulting from deformation of the squeegee that occurs when a sword squeegee is applied.

  Further, since the squeegee pressure is effectively supplied in a form that suppresses deformation of the squeegee, there is an effect that the printing condition margin is expanded.

  Furthermore, a squeegee squeegee with an optimized squeegee shape is attached perpendicularly to the mask surface, and the angle formed between the rubber squeegee surface on the side contacting the paste-like material and the mask plate becomes the attack angle during printing. In addition, it is possible to realize a printing stroke (referring to a printing distance, meaning a predetermined printing range + an approaching distance) with a smaller mask than an inclined arrangement squeegee for enlargement of a printing area. Accompanying this, there is also an advantage that the maintenance and management of the mask is stabilized as compared with the large mask.

Pasty material filling squeegee according to the invention, and the pasty material filling how can be utilized for the production of double-sided or multilayer circuit board used in various electronic apparatuses.

It is sectional drawing for demonstrating the paste material filling squeegee which concerns on Embodiment 1 of this invention. It is a schematic diagram for demonstrating the paste filling operation | movement by the paste-form material filling apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the paste material filling squeegee and paste filling method which concern on Embodiment 1 of this invention. It is a figure explaining the paste filling shape which concerns on Embodiment 1 of this invention. It is sectional drawing of the squeegee sword tip at the time of attaching a squeegee inclining.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Squeegee 2 Mask 3 Squeegee axis | shaft 4 Paste 5a 1st holder 5b 2nd holder 6 Mask plate frame 7 Printing machine stage 8 Film-like sheet 9 Ceramic layer 10 Carrier film layer 11 Via diameter 11p of ceramic layer Filling diameter 12 Filling Dent

Claims (2)

When filling the via hole formed in the base material through the mask with the paste-like material, a constant pressure is applied to the mask to push the paste-like material in the filling direction at a constant speed along the mask. A squeegee for filling a paste-like material used so as to advance ,
The cross-sectional shape of the squeegee that is in contact with the mask is configured such that, when the squeegee axis is perpendicular to the mask, the angle formed with the mask is different from the left and right, and the squeegee axis is perpendicular to the mask. In this state, the angle formed between the surface on the side touching the paste-like material and the mask is a contact angle, and the angle between the surface on the side where the squeegee does not touch the paste-like material and the mask is the anti-contact angle. The contact angle is configured to be larger than the anti-contact angle,
The squeegee tip angle is set to 110 degrees to 130 degrees, and the squeegee surface of the squeegee that is in contact with the paste-like material and the mask are used to have an angle of 20 degrees to 40 degrees. A squeegee for filling paste-like material. A method for filling a paste material using the paste material filling squeegee according to claim 1,
A paste-like material filling method comprising: filling a substrate with a certain gap from a mask and filling the mask with a squeegee axis at a right angle from above to below.

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