JPH07125176A - Squeegee of cream solder printing machine - Google Patents

Abstract

PURPOSE:To prevent the generation of printing inferiority by applying proper printing pressure to a surface to be printed at the time of screen printing by providing a plurality of slits opened to the non-contact end edge of a mask to a squeegee material. CONSTITUTION:A squeegee material 34 has a rectangular cross section having seven slits 34a opened to the non-contact end edge of a mask and the dimensions between the slits 34a are set to the same pitch dimension. When there is no warpage in a printed circuit board P at the time of printing, the squeegee material is not deformed. When there is warpage in the printed circuit board P, the squeegee material receives load from the surface to be printed of the printed circuit board P so as to change the opening width of each of the slits 34a and is deformed while it rotates the press elements 33a, 33b of two pairs of left and right press arms 35. First left and right connection arms 39 are shaken corresponding to the shaking quantity of two pairs of left and right press arms 35 so as to follow the deformation of the squeegee material and a second connection arm 40 is shaken corresponding to the shaking quantity. Therefore, the squeegee material 34 can correspond to the printed circuit board P large or small in warpage quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squeegee for a cream solder printing machine for applying cream solder onto a circuit board using a mask such as a metal screen.

[0002]

2. Description of the Related Art In recent years, with the development of surface mounting technology, leads of electronic parts are inserted into lead holes of a circuit board from the front side, and the insertion ends of the leads are dip-soldered from the back side to the circuit board. Instead of the dip soldering mounting method, a reflow soldering mounting method in which cream solder is applied on a circuit board and electronic components are reflow soldered to the cream solder is becoming popular.

To mount an electronic component on both component mounting surfaces of a circuit board using such a reflow soldering mounting method, first, the electronic component is reflow soldered on one component mounting surface, and then this component is mounted. This is done by reversing the mounted circuit board and then reflow soldering the electronic component to the other component mounting surface.

In this case, for solder printing on the circuit board, a printing screen (mask) 2 is aligned on the circuit board 1 as shown in FIG. 7, and the circuit board is opened from an opening (not shown) of the screen 2. Squeegee material 3 on top of arrow A
Screen printing is used in which the cream solder 4 is extruded and applied by a moving operation in the direction indicated by.

In the figure, reference numeral 5 indicates a backup plate 6 having a large number of pin holes (not shown) arranged in parallel in the vertical and horizontal directions at equal intervals and a pin hole (not shown) of the backup plate 6. It is a backup holder consisting of a pin 7 that can be inserted and removed.

The backup holder 5 has a function of correcting the warp deformation caused by the weight of the electronic component (not shown) and thermal strain at the time of reflow soldering mounting.

By the way, what is important in this type of screen printing is to apply an appropriate printing pressure by the squeegee material 3 to the entire component mounting surface of the circuit board 1.

That is, when the printing pressure is low, the cream solder 4 remains thin on the screen 2, the printed film thickness on the circuit board 1 becomes large after the screen is removed, and when the printing pressure by the squeegee material 3 is high, the squeegee is high. This is because the material 3 enters the opening (not shown) of the screen 2 and the printed film thickness on the circuit board 1 becomes small.

In this case, in the former case (when the printing pressure is low), fine pitch leads (not shown) are formed on the circuit board 1.
When an integrated circuit device (not shown) having the above is mounted, the lead (not shown) is likely to be short-circuited due to the excessive amount of the cream solder 4.

On the other hand, in the latter case (when the printing pressure is high), insufficient connection of the electronic component (not shown) to the circuit board 1 occurs due to the insufficient amount of the cream solder 4.

These phenomena are caused by the circuit board 1 to be printed.
When the flatness is high (0.1 mm or less), it is avoided, but when the flatness is low (0.3 mm to 0.5 mm), it is not avoided.

For example, when electronic components (not shown) are mounted on both component mounting surfaces of the circuit board 1 by reflow soldering, the first reflow soldering mounting (circuit board 1 is 2
Since the circuit board 1 as shown in FIG. 8 is distorted by passing through the furnace of 40 ° to 250 °), high quality printing is not performed before the reflow soldering and mounting of the second surface.

Conventionally, for this type of screen printing, FIG.
A squeegee 1 (square squeegee) having a square-shaped squeegee material 1a made of urethane rubber as shown in FIG. 10 or a squeegee 2 having a squeegee material 2a made of urethane rubber and having a rectangular shape in cross section as shown in FIG. A cream solder printer equipped with a squeegee is used.

The screen printing by the squeegees 1 and 2 of the cream solder printing machine is performed by deforming a part of the squeegee materials 1a and 2a in accordance with the warp deformation (concave portion) of the circuit board 1.

[0015]

However, in the former case, since the squeegee material 1a is formed in a square shape in cross section, only a small portion can be projected to the outside of the squeegee holder. The amount of deformation is small.

On the other hand, in the latter case, since the squeegee material 2a is formed in a rectangular shape in cross section, the squeegee material 2a is deformed by increasing the external protrusion amount as compared with the squeegee 1 having a square shape in cross section. Although the amount can be increased, the warp amount of the circuit board 1 is 0.1 mm to 0.2 mm.
It can only deal with the case where the warp amount is moderate.

As a result, when the warp amount of the circuit board 1 is large (0.3 mm to 0.5 mm), proper printing pressure cannot be applied to the surface to be printed by the squeegees 1 and 2 during screen printing, and printing failure occurs. There was a problem that occurs.

The present invention has been made in view of the above circumstances, and provides a squeegee for a cream solder printing machine capable of applying an appropriate printing pressure to a surface to be printed at the time of screen printing and preventing the occurrence of printing defects. It is provided.

[0019]

A squeegee of a cream solder printing machine according to the present invention (claim 1) comprises a squeegee material provided with a plurality of slits which are opened at a non-mask contact edge.

A squeegee for a cream solder printing machine according to another second aspect of the present invention (claim 2) is at least a pair of pressing arms having two pressing elements which can be pressed on both sides of the slit on the slit side end surface of the squeegee material. Is attached so as to be swingable, and an arm connecting mechanism having a swinging arm that pivotally supports the central portion of the pressing arms of each pair in the arm longitudinal direction is additionally provided.

A squeegee of a cream solder printing machine according to another third invention (Claim 3) of the present invention is provided with at least two pressing elements which can be pressed on both sides of the slit on the slit side end surface of the squeegee material. The pusher is composed of a compression coil spring.

A squeegee of a cream solder printing machine according to another fourth invention (Claim 4) of the present invention is one in which the pressing element is constituted by a roller.

[0023]

In the present invention, the squeegee material is deformed when it is subjected to a load that changes the opening width of the slit from the circuit board during printing.

In another second aspect of the present invention, the squeegee material is deformed when subjected to a load that changes the opening width of the slit from the circuit board at the time of printing, and the pressing arm and the rocking follow the deformation. The arm swings.

In another third aspect of the present invention, the squeegee material is deformed when subjected to a load that changes the opening width of the slit from the circuit board during printing, and the compression coil spring expands and contracts following this deformation. To do.

According to another fourth aspect of the present invention, when a squeegee member receives a load from the circuit board that changes the opening width of the slit during printing, the squeegee member deforms while rotating the roller as a presser.

[0027]

Embodiments of the present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 is an exploded perspective view of a squeegee of a cream solder printing machine according to the present invention, and FIGS. 2A and 2B are front and side views showing a squeegee of the cream solder printing machine of the present invention. Figure, Figure 3 (A) and (B)
Is a sectional view taken along the line A ₁ -A _{1 and a} line B ₁ -B _{1 in} FIG.
Figure 4 (A) and (B) is A ₂ -A ₂ line sections and B ₂ -B ₂ sectional view taken along line of FIG. 2 (A).

In the figure, reference numeral 11 is a squeegee holder for screen printing, which is movable in the printing direction, and is composed of two main and sub holders 12 and 13 having different widthwise dimensions, and a cream solder printing machine main body (not shown). It is rotatably provided.

Of these, a stopper 14 extending in the left-right direction (longitudinal direction) of the holder is provided at one end of the main holder 12.
Are integrally provided, and two spacers that have a through hole 15a that opens in the left-right direction and a screw hole 15b that opens in the sub-holder side are provided at the corners of the other end edge and that abut on the corners of the sub-holder 13. The block 15 is integrally provided.

Four screw insertion holes 16 are provided in the central portion of the main holder 12 in the width direction and open on both sides of the holder and arranged in parallel in the holder longitudinal direction at predetermined intervals.

Further, at the spacer block side edge (counter stopper side edge) of the main holder 12, there are five screw insertion holes 17 arranged in parallel in the holder longitudinal direction at a predetermined interval.
(Only four are shown) and pin insertion holes 18 opening on both front and back sides of the holder are provided in the vicinity of the screw insertion hole at the center of these screw insertion holes 16 (generally at the center in the holder longitudinal direction).

The main holder 12 and the spacer block 15 are provided with screw holes 19 which open inside and outside the through hole 15a.

On the other hand, a stopper 20 extending in the holder longitudinal direction is integrally provided at one end edge of the sub holder 13, and a screw hole 21a corresponding to the screw insertion hole 17 is provided at the other end edge. The main holder 12 that has the tip surface
The spacer wall 21 that abuts on the edge of the spacer block is integrally provided.

Screw insertion holes 22 and 23 corresponding to the screw hole 15b and the screw insertion hole 16 are provided at the stopper side edge of the sub holder 13.

The sub-holder 13 has a pin insertion hole 18 which is open at the front and back sides of the holder at a substantially central portion in the longitudinal direction.
Is provided with a pin insertion hole 24.

Numeral 25 is four first collars arranged in parallel in the holder longitudinal direction at a predetermined interval.
It is interposed between Nos. 2 and 13 and is entirely formed by a cylindrical body having a screw hole 25a communicating with both the screw insertion holes 16 and 23.

Reference numeral 26 is a cylindrical second collar having a pin insertion hole 26a opened in the same axial direction as the axial direction of the pin insertion holes 18 and 24, and is interposed between two connecting arms described later. .

The outer diameter of the second collar 26 is set larger than the outer diameter of the first collar 25, and the height thereof is smaller than the height of the first collar 25.

The cylindrical wall of the second collar 26 is provided with a screw hole 27 which is open in the cylinder radial direction and communicates with the pin insertion hole 26a.

Reference numeral 28 denotes an arm pivot pin whose both ends are exposed in the pin insertion holes 18 and 24, and is inserted and fixed in the pin insertion hole 26a of the second collar 26.

Reference numeral 29 designates eight sets of squeegee clampers which are arranged in parallel in the holder longitudinal direction at predetermined intervals, and each of which is fixed by two screws 30 to the stoppers 14 and 2.
The holders 12 and 13 are composed of two main and sub clampers 31 and 32 having steps 31a and 32a facing 0, respectively.
It is interposed between.

First cutouts 31b, 3 facing the eight pressing elements 33 made of, for example, stainless steel rollers are formed in the central portions of the main and sub clampers 31, 32 of each set in the holder longitudinal direction.
2b is formed.

Further, the main and sub clampers 31, 3 of each set are
Second cutouts 31c and 32c are formed in the second collar 25 so as to face the first collar 25 between two pairs of squeegee clampers which are adjacent to each other among the pair of squeegee clampers 29.

Reference numeral 34 is a squeegee material having a rectangular cross section, which has seven slits 34a opening at the non-contact edge of the mask.
The main and sub clampers 31 and 32 of both sets hold the pressure, and the whole is formed of an elastic body made of, for example, urethane rubber having a rubber hardness of 90 degrees. The dimension of each slit of the squeegee material 34 is set to the same pitch dimension.

Reference numeral 35 denotes two pairs of pressing arms arranged in parallel in the holder longitudinal direction at a predetermined interval.
It is provided between 2 and 13 so as to be swingable.

The pressing arms 35 have a base piece 36 having a pin insertion hole 36a opening in the arm thickness direction at the center of the arm, and two of the pressing elements 33 integrally provided at both ends of the base piece 36. One pusher is the squeegee material 3
It is formed by an arm having a substantially U-shape in a plan view, which is composed of two side pieces 37 that can be pressed against both sides of the slit on the slit-side end surface of No. 4.

Reference numeral 38 denotes a swinging mechanism as an arm connecting mechanism, which includes two pairs of first connecting arms 39 that swingably pivotally support the central portion in the arm longitudinal direction of the pressing arms 35 of each pair, and the pair of first connecting arms 39. The first connecting arm 39 is composed of a pair of second connecting arms 40 pivotably supporting the central portion of the first connecting arm 39 in the arm longitudinal direction, and is provided between the main and sub holders 12, 13.

Of these pairs, the first connecting arms 39 of each pair are
Two pin insertion holes 39a corresponding to the pin insertion holes 36a of each pair of the pressing arms 35 and these pin insertion holes 3
Pin insertion holes 39b located between 9a are provided.

On the other hand, each second connecting arm 40 has two pin insertion holes 40a corresponding to the pin insertion holes 39b and a pin insertion hole which is located between the two pin insertion holes 40a and into which the arm pivot pin 28 is inserted. A hole 40b is provided.

Reference numerals 41 and 42 denote first screws for connecting the holders, which are inserted into the screw insertion holes 16 and 23 and screwed into the screw holes 25a of the first collar 25.

Reference numeral 43 denotes a second screw for connecting the holder, which is inserted into the screw insertion hole 17 and screwed into the screw hole 21a of the spacer wall 21.

Reference numeral 44 designates a third screw for connecting the holder, which is inserted through the screw insertion hole 22 and the spacer block 1
5 is screwed into the screw hole 15b.

Reference numeral 45 is a first pivot pin for rotating the holder,
A part of the spacer block 15 is attached so as to face the inside of the through hole 15a, and a notch 45a having a U-shaped cross section is formed at the tip portion.

Reference numeral 46 denotes a second pivot pin whose both ends are exposed in the pin insertion hole 39a and is inserted in the pin insertion hole 36a. Of the second pivot pins 46, the height of the two second pivot pins at the central portion is set to be smaller than the height of the second pivot pins at the two side portions.

Reference numeral 47 is a third pivot pin whose both ends are exposed in the pin insertion hole 40a and is inserted in the pin insertion hole 39b.

Reference numeral 48 denotes a plastic sheet that closes the opening of the sub holder of the slit 34a, and is adhered to both side edges of the main holder 12 so as to cover a part of the squeegee material 34, and the whole is transparent. Is formed by a flexible plastic sheet having.

Numerals 49 and 50 are screws for attaching pins, which are screwed into the screw holes 19 and 27, respectively.

In the squeegee for the cream solder printing machine thus constructed, the squeegee material 34 does not deform when the circuit board P has no warp amount during printing as shown in FIG. As shown in (B), when the circuit board P has a warp amount, the squeegee material 34 receives a load from the printed surface of the circuit board P that changes the opening width of the slit 34a and rotates the pressing element 33. As it transforms,
Following this deformation, the pressing arm 35, the first connecting arm 39, and the second connecting arm 40 swing.

At this time, of the two pairs of left and right pressing arms 35, the pressing elements 33a of the pair of pressing arms 35 on the left side receive a load from the convex portion P ₁ of the circuit board P via the squeegee material 34 and are equal to this load. each pressure arm 35 until the pushing element 33b the load received via the squeegee member 34 from the recess P ₂
Swings clockwise and counterclockwise around the second pivot pin 46, and the first connecting arm 39 moves the third pivot pin 47 according to the amount of swing movement (load amount) of each pressing arm 35. Swing counterclockwise around.

On the other hand, each pressing element 33a of the pair of right pressing arms 35 receives a load from the convex portion P ₁ of the circuit board P via the squeegee material 34, and a load equal to this load is applied to the pressing element 33.
Each pressing arm 35 swings clockwise and counterclockwise around the second pivot pin 46 until b is received from the recess P ₂ through the squeegee member 34, and the swinging motion amount of each pressing arm 35 ( The first connecting arm 39 moves to the third position according to the load amount).
It swings counterclockwise around the pivot pin 47.

The second connecting arm 40 moves the arm pivot pin 2 in accordance with the swinging amount of the left and right first connecting arms 39.
Swing clockwise around 8.

Therefore, in the present embodiment, the squeegee material 34 can be applied not only to the circuit board P having a small warp amount during screen printing but also to the circuit board P having a large warp amount (0.3 mm to 0.5 mm). Therefore, it is possible to apply a uniform and appropriate printing pressure to the printed surface of the circuit board P.

Further, in the present embodiment, the fact that the pusher 33 is a roller makes the squeegee material 34 easily deformed when the squeegee moves.

Further, in this embodiment, it is possible to apply an appropriate printing pressure to the circuit board P in accordance with the warp amount.
It is possible to alleviate the restrictions set in the designing stage in order to maintain the flatness, and to reduce the number of operations performed in the manufacturing process to prevent the warpage of the circuit board P.

In addition, in the present embodiment, it is possible to apply a uniform proper printing pressure to the printed surface of the circuit board P by the swing motion of the first connecting arm 39, the second connecting arm 40 and the pressing arm 35. It does not require the skill of the printing operator.

Further, in this embodiment, since the slit 34a of the squeegee material 34 is closed by the plastic sheet 48, it is possible to prevent the slit clogging due to the cream solder during printing.

Further, in this embodiment, as shown in FIG. 5, each unit is unitized by a case C which covers a part of the pressing element 33, the swinging mechanism 38, the pressing arm 35, and the squeegee material 34. The parts can be protected, and the squeegee holder 11 can be easily attached.

Although the pressing element 33 is a roller in this embodiment, the present invention is not limited to this, and the warp amount of the circuit board P is small (0.2 m).
In the case of m to 0.3 mm), even if the squeegee structure is simplified by using the compression coil spring 51 as the pressing element as shown in FIG. 6, the effect similar to that of the embodiment can be obtained.

Further, in the present embodiment, the swing mechanism 38
Shows the one including the first connecting arm 39 and the second connecting arm 40, but the present invention is not limited to this, and can be appropriately changed according to the longitudinal dimension of the squeegee material 34 and the like.

In addition, it goes without saying that the number of pressing elements, arms and the like in the present invention is not particularly limited to the above-mentioned embodiment.

Incidentally, the clamper 29 is used in this embodiment.
Since the squeegee material 34 having a rectangular cross section can be held, the conventional squeegee material (flat squeegee material shown in FIG. 10) can also be held.

Further, the cream solder printing on the circuit board in this embodiment is performed in the same manner as in the past.

That is, a screen for printing is placed on the circuit board, and the squeegee material is moved from the opening of the screen onto the circuit board to extrude and apply the cream solder.

[0075]

As described above, according to the present invention, the squeegee material is provided with a plurality of slits which are opened to the non-mask contact edge, so that the squeegee material changes the opening width of the slits from the circuit board during printing. It deforms when subjected to such a load.

Therefore, since the squeegee material can be applied not only to a circuit board having a small amount of warp during screen printing but also to a circuit board having a large amount of warp, an appropriate printing pressure can be applied to the printed surface of the circuit board. It is possible to prevent the occurrence of printing defects.

According to a second aspect of the present invention, at least a pair of pressing arms having two pressing elements that can be pressed on both sides of the slit are swingably attached to the slit side end surface of the squeegee material, and the arm lengths of the pressing arms of each pair. Since an arm connecting mechanism having a swinging arm that pivotally supports the central part in the direction is attached, the squeegee material is deformed when subjected to a load that changes the opening width of the slit from the circuit board during printing, and it follows this deformation. As a result, the pressing arm and the swinging arm swing, so that the printing pressure applied by the pressing element to the printed surface of the circuit board during printing can be made uniform.

According to the present invention, at least two squeegee members which can be pressed against the slit side end surface on both sides of the slit.
Since two pressers are attached and each presser is composed of a compression coil spring, it deforms when the squeegee material receives a load that changes the opening width of the slit from the circuit board during printing, and it follows this deformation. The compression coil spring expands and contracts.

Therefore, since the squeegee material can apply a proper printing pressure to the printed surface of the circuit board, the occurrence of printing defects can be prevented with a relatively simple structure.

According to the present invention, since the pressing element is a roller, the squeegee material is deformed while being rotated while being subjected to a load which changes the opening width of the slit from the circuit board during printing. The squeegee movement operation can be performed smoothly.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a squeegee of a cream solder printing machine according to the present invention.

2A and 2B are a front view and a side view showing a squeegee of the cream solder printer according to the present invention.

3A and 3B are cross-sectional views taken along line A ₁ -A _{1 and} line B ₁ -B _{1 of} FIG. 2A.

[4] (A) and (B) A ₂ -A ₂ line sections and B ₂ -B ₂ sectional view taken along line of FIG. 2 (A).

5 (A) and 5 (B) are schematic views shown for explaining an arm swinging operation of the squeegee of the cream solder printing machine according to the present invention.

FIG. 6 is a schematic view showing a squeegee of a cream solder printing machine according to another invention of the present invention.

FIG. 7 is a side view shown for explaining screen printing with a squeegee of a conventional cream solder printing machine.

FIG. 8 is a front view showing a squeegee material and a circuit board at the time of screen printing using a squeegee of a conventional cream solder printer.

FIG. 9 is a side view showing a squeegee (1) of a conventional cream solder printing machine.

FIG. 10 A squeegee (2) of a conventional cream solder printing machine
FIG.

[Explanation of symbols]

 33 ... Pusher 34 ... Squeegee material 34a ... Slit 35 ... Pressing arm 38 ... Swing mechanism 39 ... First connecting arm 40 ... Second connecting arm

Claims (4)

[Claims] 1. A printing mask is aligned on a circuit board,
In a cream solder printing machine for squeezing cream solder by soldering the squeegee material onto the circuit board from the opening of the mask, the squeegee material is provided with a plurality of slits opening at the non-mask edge of the mask. The squeegee of the cream solder printing machine, which is characterized by that. 2. At least a pair of pressing arms having two pressing elements that can be pressed on both sides of the slit are swingably attached to an end surface of the squeegee material on the slit side, and
2. The squeegee for a cream solder printing machine according to claim 1, further comprising an arm connecting mechanism having a swinging arm that pivotally supports a central portion of each pair of pressing arms in the arm longitudinal direction. 3. The cream according to claim 1, wherein the squeegee material is provided with at least two pressing elements that can be pressed on both sides of the slit on the slit side end surface, and each of these pressing elements is constituted by a compression coil spring. Squeegee for solder printer. 4. The squeegee for a cream solder printing machine according to claim 2, wherein the pressing element is constituted by a roller.