JP3232876B2 - Screen printing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing apparatus capable of appropriately controlling a solvent contained in cream solder.

[0002]

Prior to mounting electronic components on a board, cream solder is applied (printed) to the board by a screen printing apparatus. By the way, cream solder originally has a paste form dissolved in a solvent that is easily vaporized. However, when the ambient temperature around the cream solder is high, or when a large amount of air flows around the cream solder, a large amount of the solvent evaporates and the cream solder becomes hard, and printing becomes impossible.

For this reason, in a conventional screen printing apparatus,
A cover that covers the entire screen printing apparatus is provided, and the temperature of the atmosphere in the cover is adjusted by, for example,
The temperature was controlled at about 5 ° C. ± 3 ° C.

[0004]

However, even though the entire screen printing apparatus is covered with a cover, it is necessary to put the substrate in and out of the screen printing apparatus, and it is necessary to take the substrate in and out of the screen printing apparatus and the space for taking in and out means such as a conveyor. In practice, the cover has a plurality of large openings. Therefore, gas flows into and out of the cover through these openings.
In addition, a large amount of the solvent vaporized inside the cover is released to the outside of the cover, so that the cream solder is easily hardened, and there is a problem that printing cannot be performed for a long time.

Accordingly, an object of the present invention is to provide a screen printing apparatus which can reduce the loss of solvent and extend the life of the cream solder.

[0006]

According to the present invention, there is provided a screen printing apparatus, comprising: positioning means for positioning a substrate; a screen mask to be superimposed on the positioned substrate; and applying cream solder to the substrate by sliding on the screen mask. comprising a squeegee for, and a surrounding cover which surrounds the periphery of the squeegee above the screen mask, and the enclosing
When a gap is provided between the cover and the screen mask
In both cases, the gas in the surrounding cover is sucked, and the sucked gas is sucked.
Release all or part of the air out of the surrounding cover from
Concentration adjusting means for returning other gases into the surrounding cover;
Provided .

[0007]

According to the above construction, the squeegee for printing cream solder is covered with the screen mask and the surrounding cover. Here, since there is no substrate and no means for loading and unloading the substrate above the screen mask, it is not necessary to open an opening for loading and unloading the substrate in the surrounding cover. Therefore, loss of the solvent vaporized from the cream solder can be suppressed, and the life of the cream solder can be extended.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the screen printing apparatus according to an embodiment of the present invention (line A-A in FIG. 1), and FIG. FIG. 4 is an enlarged view of the cooling element in FIG.

In FIG. 1, reference numeral 1 denotes an X table driven by an X motor 2, and 3 denotes a Y motor 4 mounted on the X table 1.
And 5, a substrate holder provided on the Y table 3 for holding the substrate 6. These X table 1, Y table 3, and substrate holder 5 correspond to positioning means. 7 is a screen mask superimposed on the substrate 6, 8 is a mask frame holding the screen mask 7, 9,
10 is a guide rail extending in a direction perpendicular to the plane of FIG.
Are movable plates 14, 15 which are driven by moving means (not shown) in a direction perpendicular to the plane of FIG. 1 by slidingly engaging sliders 12, 13 provided at a lower portion with the guide rails 9, 10. Is a pair of elevating guides provided on the upper surface of the movable plate 11, and 16 and 17 are elevating guides 14, 1
5 and a squeegee 1 at the lower end.
A guide rod 19 connected to 8 is a cylinder disposed between the lifting guides 14 and 15 of the movable plate 11, and a lower end of the rod 20 is connected to an upper end of the squeegee 18.
When the cylinder 19 is driven to project and retract the rod 20, the squeegee 18 is moved up and down while being guided by the elevating guides 14 and 15, and the lower edge of the squeegee 18 can be brought into contact with and separated from the screen mask 7. Reference numeral 21 denotes a rectangular cylindrical surrounding cover provided on the lower surface of the movable plate 11 and covering the periphery of the squeegee 18. As shown, no opening is provided on the side surface of the surrounding cover 21, and a slight gap t is interposed between the lower edge of the surrounding cover 21 and the upper surface of the screen mask 7.
Here, when the moving plate 11 moves in the direction perpendicular to the plane of FIG.
The surrounding cover 21 moves together with the squeegee 18. The surrounding cover 21 is made of a transparent acrylic plate or the like so that the lower surface of the movable plate 11, the surrounding cover 21 and the inside of the main temperature control room A surrounded by the screen mask 7 can be seen, and the surrounding cover 21 is moved. It is preferable to be detachably attached to the plate 11 from the viewpoint of ease of maintenance. Hereinafter, the space covered by the surrounding cover 21 is referred to as a main temperature control room A.

Next, the density adjusting means will be described. 22
Denotes a solution collection box provided above the moving plate 11;
Reference numeral 3 denotes an air dryer stored in the solution recovery box 22. This air dryer 23 has one air inlet 23a.
And two discharge ports 23b and 23c, and has a function of separating only air from the gas entering from the blow-in port 23a to one discharge port 23b and separating the other gas to the other discharge port 23c. In this embodiment, the main temperature control room A and the air dryer 2
3 is connected to the discharge port 23b by the suction pipe 24.
And the suction device 26 are connected to the discharge port 23 by the first discharge pipe 25.
c and the main temperature control chamber A are connected by the second discharge pipe 27, respectively. Therefore, when the suction device 26 is driven, the gas containing the vaporized solvent from the main temperature control chamber A reaches the air dryer 23 as shown by the arrow N1. Only a part of the air is collected by the suction device 26, and the other gases (including all of the vaporized solvent that has reached the air dryer 23) are supplied to the main temperature control chamber A as indicated by an arrow N2. Return to Further, air corresponding to the air collected by the suction device 26 flows into the main temperature control chamber A from a gap t between the screen mask 7 and the lower edge of the surrounding cover 21. Therefore, the concentration of the vaporized solvent in the main temperature control chamber A remains almost constant.
Further, the inside of the main temperature control room A has a slightly negative pressure with respect to the outside of the surrounding cover 21, and even though air may flow into the main temperature control room A from outside, the main temperature control room A The vaporized solvent does not flow out through the gap t. Therefore, not only the loss of the solvent can be reduced as much as possible, but also the solvent harmful to the human body can be prevented from diffusing out of the screen printing apparatus.

Next, the temperature adjusting means will be described. FIG.
, S1 is a temperature sensor for detecting an ambient temperature in the main temperature control room A, S2 is a humidity sensor for similarly detecting humidity,
Reference numeral 28 denotes a unit box provided on the movable plate 11, and the inside thereof is a sub-temperature control room B. As shown in the drawing, the sub-temperature control room B is provided outside the main temperature control room A, and air is allowed to enter and exit through the communication portion 29 opened in the movable plate 11. Numeral 31 denotes a cooling / heating element, as shown in FIG. 3, in which negative (N) and positive (P) thermoelements are alternately arranged to form a + side metal electrode 31a and a − side metal electrode 3a.
1b. Then, the metal electrodes 31a, 3
When a DC voltage is applied to 1b, the + side metal electrode 31a absorbs heat and the-side metal electrode 31b releases heat.
This exchange of heat is performed by radiation heat. In FIG. 1, reference numeral 32 denotes a cooling plate exposed in the sub-temperature control chamber B and thermally coupled to the + side metal electrode 31a, 35 represents a radiation fin thermally coupled to the − side metal electrode 31b, and 36 represents a radiation fin 35. Is a cooling fan. In addition, since the temperature of the cooling / heating plate 32 may be reduced and the cooling / heating plate 32 may be condensed, a drainage tank 33 is provided below the cooling / heating plate 32. The drain is drained by the drainage device 34. Of course, instead of draining by the drainage device 34, water may be absorbed by the water-absorbing polymer, and may be evaporated again when the temperature rises. Reference numeral 37 denotes a controller that inputs outputs of the temperature sensor S1 and the humidity sensor S2 and outputs an appropriate output to the cooling element 31. Conventionally, air whose temperature and humidity have been adjusted is blown from an air controller into a cover that covers the entire screen printing apparatus, but in this case, the solvent discharged along with the air discharged from the cover is also discharged outside the cover. There is a disadvantage. However, in this embodiment, the temperature and the humidity in the sub-temperature control room B are controlled by the radiant heat (at this time, the airflow in the sub-temperature control room B is slight), and the air after the control is passed through the communication part 29. The main temperature control room A is configured so as to allow a flow into the main temperature control room A, and the main temperature control room A generates almost no airflow, so to speak, the sub temperature control room B.
Thus, the temperature and humidity are indirectly controlled, and the vaporized solvent hardly flows out of the main temperature control chamber A.

[0012]

As described above, according to the present invention, the loss of the vaporized solvent can be suppressed as much as possible, and the life of the cream solder can be extended.

[Brief description of the drawings]

FIG. 1 is a sectional view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the screen printing apparatus according to one embodiment of the present invention (FIG. 1A-A line);

FIG. 3 is an enlarged view of a cooling element according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X table 3 Y table 5 Substrate holder 6 Substrate 7 Screen mask 18 Squeegee 21 Surrounding cover 23 Air dryer 29 Communication part 31 Cooling element A Main temperature control room B Sub temperature control room t Gap

Claims (1)

(57) [Claims] 1. A positioning means for positioning a substrate, a screen mask superimposed on the positioned substrate, a squeegee sliding on the screen mask to apply cream solder to the substrate, and a squeegee above the screen mask. And a surrounding cover surrounding the periphery of the squeegee , and between the surrounding cover and the screen mask.
A gap is provided in the space, and gas in the surrounding cover is sucked.
And all or part of the air from the sucked gas
Release outside the bar and return other gases into the surrounding cover
A screen printing apparatus comprising a density adjusting means .