JPS5821835B2 - screen printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screen printing device suitable for printing a conductive paste on a substrate using a screen plate. The present invention relates to a screen printing device suitable for forming.

Conventionally, plate glass on which thin electrical resistance wires are formed has been used as window glass for automobiles, ships, railroad vehicles, airplanes, etc., and when water vapor condenses or freezes on the plate glass, the resistance on the plate glass surface increases. It is used as an anti-fog glass window that heats the plate glass by applying electricity to the filaments to remove condensation of water vapor or ice, thereby removing fogging that occurs on the plate glass.

A glass plate having such thin electric resistance wires formed thereon can be produced using a support tool that supports the glass plate, a screen plate provided facing the top surface of the glass plate, and a squeegee tool that moves back and forth by pressing on the screen of the screen plate. Using a screen printing device, a conductive paste for printing is supplied onto the screen so as to have a desired conductivity after baking, and then the conductive paste is applied to a plate glass in thin lines using a so-called mesh screen printing method using a squeegee. After printing and drying, the printed and dried conductive paste is baked into a resistance wire in the sheet glass bending process or strengthening process, and if necessary, the resistance wire is plated with metal to form the resistance wire. The resistance value of the strips was adjusted and reinforced.

It is desired that each of the plate glasses on which these electrical resistance stripes are formed has a predetermined constant resistance value.
This resistance value is determined by the adjustment of the conductive paste, the printing process, and the metal plating process. Particularly in cases where the metal plating process is omitted, it is not possible to adjust the resistance value of the resistive wire after printing the conductive paste, so the resistance value is determined by the conductive paste adjustment, printing process, and metal plating process. It was necessary to adjust the paste and adjust the resistance value of the resistance strip during the printing process.

However, in the printing process using conventional screen printing equipment, the resistance value of the resistance strip is adjusted by the pressure with which the squeegee presses on the screen plate, the contact angle of the squeegee tool with the screen plate, and the contact angle between the screen plate and the printing plate. This is possible by adjusting the amount of conductive paste extruded from the mesh of the screen plate depending on the distance to the substrate to be used, etc.
It is extremely difficult to correct deviations in resistance from a predetermined value by quantitatively changing the amount of printed conductive paste, and when the resistance value deviates significantly from the predetermined value, it is no longer possible to correct it by simply manipulating the printing conditions described above. This is impossible, and it is necessary to collect the conductive paste supplied onto the screen plate, readjust the conductive paste so that it has a predetermined resistance value, and wash and dry the screen plate. The equipment had to be stopped for a long time.

The present invention relates to an improvement of the screen printing apparatus having the above-mentioned drawbacks. A screen printing apparatus comprising a screen plate, a squeegee tool that moves back and forth by pressing on the screen of the screen plate, and a conductive paste supply means for supplying a predetermined amount of conductive paste onto the screen. two variable weighing devices whose means supply predetermined amounts of conductive pastes of two different compositions according to the printing operation of a squeegee tool; and conductive pastes of two kinds of compositions supplied from the two variable weighing devices. A screen printing apparatus is characterized in that it is comprised of a mixing and supplying device that mixes and supplies the mixture onto a screen.

The conductive paste used in the present invention is made into a paste by suspending metal particles such as silver, low-temperature melting glass frit, etc. in an organic solvent.

The conductivity of this conductive paste after baking is determined by the ratio of metal particles such as silver in the conductive paste that contribute to electrical conduction and low-temperature melting glass frit to obtain strong adhesion to the printed substrate. Therefore, a low-resistance conductive paste with a relatively large proportion of metal particles and a high-resistance conductive paste 1- with a relatively small proportion of metal particles are adjusted in advance to a conductive paste state suitable for screen printing, and the former and the latter are mixed. By appropriately selecting the mixing ratio of , the conductivity of the conductive paste after baking can be set to a target value, and the resistance value of the resistance wire can be set to a predetermined resistance value.

For example, the relationship between the mixing ratio of two types of conductive paste adjusted to be suitable for screen printing and the resistance value of the resistance wire is as follows: Then, the resistance value RΩ of the resistance wire is logR-(AogR17ogR2)Xm-1-Aog
It is approximated by R2(1).

Here, R1 is the resistance value of the resistance line when only the low-resistance conductive paste is printed, and R2 is the resistance value of the resistance line when only the high-resistance conductive paste is printed.

Therefore, the mixing ratio of low-resistance conductive paste and high-resistance conductive paste to obtain a predetermined resistance value RoΩ of the resistance wire is
From equation (1), mo-(log Ro-logR2)
/ (lc>gRl-6ogR2) (2) is determined.

In addition, due to abrasion of the squeegee and screen plate due to continuous printing operations, and changes in the conductive paste due to the dissipation of volatile substances in the conductive paste deposited on the screen plate, the resistance value Ro on the desired resistance line may change. When the resistance value of the strip shifts by ΔRΩ, Δm=Oog(Ro+ΔR)−logRo')/(lo
gRl - logR2) The resistance value Ro can be corrected by the correction value Δm from the mixture ratio mo shown in (3).

The present invention uses a conductive paste mixing and supplying device that mixes conductive pastes of two or more compositions in a predetermined ratio according to the printing operation of a squeegee tool to make a conductive paste of a desired composition and supplies it onto the screen. Therefore, the conductive paste mixed in a predetermined ratio can be supplied onto the screen according to the number of printing operations of the squeegee tool, so the composition of the conductive paste to be printed can be kept constant and the printing operation can be continued and printed stably. Even if the printed conductive paste deviates from the desired composition, it can be restored to the desired composition by correcting the mixing ratio of two or more types of conductive paste, so the desired composition can be achieved without interrupting the printing process. Can print conductive paste.

In the present invention, two variable weighing devices supply predetermined amounts of conductive pastes of two different compositions, and the conductive pastes of two compositions supplied from the two variable weighing devices are mixed and then mixed. By using a conductive paste mixing and supplying device consisting of a mixing and supplying device that supplies the conductive paste onto a screen, the operation for obtaining a conductive paste with a desired composition is simple, and the mixing and supplying device can ensure the mixing and supplying the desired composition. A conductive paste of the composition can be applied onto the screen.

Further, in the present invention, a container filled with conductive paste,
By using a variable weighing device comprising a press tool that pushes out a predetermined amount of the conductive paste in the container to the mixing supply device in accordance with the printing operation of the squeegee, the appropriate amount of the conductive paste is supplied to the mixing supply device in small increments. Even if the printed conductive paste deviates from the desired composition, by changing the ratio of the two different conductive pastes supplied from these variable weighing devices, the desired composition can be achieved in a relatively short time. The composition can be restored.

Furthermore, the present invention provides a container for receiving conductive pastes of two different compositions supplied from a variable weighing device, and a container for receiving conductive pastes of two different compositions supplied from a variable weighing device. A mixing supply device comprising a discharge nozzle for supplying the same amount of conductive paste in the container onto a screen, and a kneading tool located in the container for kneading and stirring the conductive paste in the container by rotation. By using this, two types of conductive pastes of different compositions supplied in small increments from a variable weighing device can be mixed homogeneously in a short time, and the receiver can mix almost the same amount of conductive paste of the desired composition as the conductive paste put in. can be provided on the screen.

Furthermore, in the present invention, a hollow cylindrical cartridge container, a tip cap having a conductive paste receiving nozzle and an air vent valve that can be attached and detached to the tip of the cartridge container, and a pressing tool that can be attached and detached to the rear end of the IJ Tsuji container. By using the filling container of the variable weighing device, when one of the conductive pastes becomes empty due to continued printing work, it can be removed from the variable weighing device main body for refilling and refilling can be carried out smoothly. As well as being able to
During refilling, trapped air can be discharged out of the cartridge container using an air release valve provided on the tip cap.

Furthermore, in the present invention, a cylindrical body having a plurality of receiving ports, a tip cap having a detachable conductive paste discharging nozzle at the tip of the body, and a detachable bearing for holding and rotating the kneading tool at the rear end of the body. The conductive paste mixing and supplying device has a cylinder having a partition wall with a removable seal part between the bearing part and the main body, and the cylinder can be removed for disassembly and cleaning as necessary, and parts can be removed. It is easy to replace the bearing due to wear, etc., and conductive paste can be prevented from entering the bearing by using a partition wall with a sealing part.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 and 2, an automobile rear window glass 1, which is a substrate to be printed, is conveyed by intermittent automatic feed rolls 2 and a V-belt conveyor 3 to a number of supports 5 attached to a glass plate support base 4.

When the window glass 1 is fed onto the support 5, it is lifted by the support 4 and the distance from the screen plate 8 is kept optimal for printing.At the same time, a positioning plate for the window glass 1 attached to the support 4 is held. After the window glass 1 and the pattern on the screen plate 8 are aligned relative to each other by being held from both sides by the plates 6 and 6, conductive paste is printed in a predetermined pattern by the printing device 7, and then the positioning plates 6 and 6 are released. , the support stand 4 is lowered and transferred to the next process by the V-belt conveyor 3 and the conveyor 2.

As shown in FIGS. 1 and 3, the printing device 7 includes a screen plate 8, a squeegee tool 9, and a conductive paste mixing and supplying device 10.

The screen plate 8 consists of a mesh screen 11 having a predetermined printing pattern and a frame 12, and the squeegee tool 9 includes a squeegee rubber 14 and a scraper 15 attached to a hardware 13.
are attached to the sliding hardware 17 via a swinging device 16, and the sliding hardware 17 is moved by forward rotation of a motor (not shown), and the squeegee rubber 14 is brought into contact with the mesh screen 11 and moved to create a conductive The paste 19 is printed on the window glass 1, and then the swinging device 16 is activated to release the squeegee rubber 1.
4 so as not to touch the mesh screen 11, and bring the scraper 15 close to the surface of the mesh screen 11, and by reversing the motor, the very small amount of conductive paste remaining on the mesh screen is returned to its original position.

In this printing process, the squeegee rubber 14 is attached to the screen 11.
Printing conditions such as the pressure applied to the top, the contact angle of the squeegee tool 13 with the screen 11, and the distance between the screen and the substrate are kept constant for each print.

The conductive paste mixing and supplying device 10 includes a screen plate 8
A variable weighing supply device 20 that determines the mixing ratio and supply amount of the secondary conductive paste 18 to be supplied to the container, and two types of primary conductive pastes 18' and 18 with different metal contents extruded from the variable weighing supply device 20. A mixing supply device 21 that homogeneously kneads and mixes the paste into the secondary conductive paste 18 at a predetermined mixing ratio and supplies it onto the screen 11.

Two types of primary conductive pastes l-18' with different metal contents
, 18" variable weighing supply device 2 that determines each extrusion amount
0 is a hollow cylindrical car that can be refilled with the primary conductive paste 18', 18'').A primary conductive paste pusher that can be attached and detached to the tip of the IJ Tsuji container 22.22 and the cartridge container 22.22.

A tip cap 25.25 with an ejection nozzle 23.23 and a valve 24.24 for releasing trapped air during refilling, a propelling screw 2B at the rear end of the cartridge container 22.22,
The cart can be attached and detached by rotation of 28 to slide inside the cart IJ containers 22, 22 via the push rods 27 and 27, and to push out the primary conductive paste (18', 1B'') from the nozzles 23, 23. A pressing tool 27 consisting of a plunger 26.26 and a push rod 27.27 connected to the plunger
'27' and a propelling screw 28°2 connected to the push rod of the pressing tool.
8 and the propulsion screw rotation ratio changing gear mechanism 29, the gear ratio selection handle G, and a power motor M1 equipped with a transmission mechanism SP that rotates the gear in forward and reverse directions.
, a switch So that opens and closes the power motor power supply according to a signal 31 issued in response to the printing operation of the squeegee tool 9, and a timer mechanism 32 that determines the time for ejecting the first conductive paste. so that the mixing ratio of the two types of primary conductive paste becomes the desired value during one round trip, and the total amount of primary conductive paste extruded becomes a value suitable for one printing amount. , the speed change mechanism SP connected to the power motor M1 is set, and the timer T of the timer mechanism 32 is set to switch S1.
．． The clutches 30 and 30 are engaged and engaged by controlling S2.

A predetermined amount of the primary conductive paste 18718'' extruded from the variable weighing device 20 passes through removable extrusion nozzles 23, 23 provided on the tip caps 25, 25 of the hollow cylindrical car 1-IJ Tsuji 22゜22. The conductive paste is sent to the conductive paste mixing and supplying device 21.

The conductive paste mixing and supplying device 21 has a removable receiving port 3.
3, a cylindrical body 34 having 33, a removable tip cap 36 having a discharge nozzle 35 for discharging the primary conductive paste 18 kneaded with two types of primary conductive pastes at the tip of the body; A removable bearing part 38 for holding and rotating the kneading tool 37 is provided at the rear end, and a bearing part 3 for the secondary conductive paste 18 is provided between the bearing part 38 and the main body conductive paste storage part.
a partition wall 40 having a removable seal portion 39 to prevent intrusion into A predetermined amount of the primary conductive paste l-18'1 B'' with different metal content extruded from the variable weighing device 20 passes through the cylindrical body 34 of the conductive paste mixing and supplying device 21 to the discharge nozzle 35. The mixture is efficiently homogenized by the action of the kneading tool 37 during the very short time it is discharged, and a predetermined mixing ratio is produced from the discharge nozzle 35 provided in the tip cap 36 according to the extrusion pitch of the variable weighing device 20. The secondary conductive paste is supplied onto the mesh screen 11 in an appropriate amount for one printing.

The kneading tool 31 is connected to the power motor M2, and a coupling 41 is provided in the middle, and each joint part of the conductive paste mixing and supplying device 21 has a removable structure, so it can be removed and disassembled as necessary as described above. In addition to being easy to clean, it is also easy to replace parts due to wear.

As described above, in the embodiment of the present invention, the conductive paste blending and supplying device 10 has two different types by selecting the speed change mechanism SP of the variable weighing amount supplying device 20 and on/off of the clutches 30 and 30 controlled by the timer mechanism 32. Receiving the primary conductive paste 1-18'1B" of a predetermined proportion having a metal content, the necessary appropriate mixing ratio of the secondary conductive paste 18 to give a predetermined resistance value to the resistance strips of the printed circuit board 1 is determined. amount,
The secondary conductive paste 1 can be supplied each time the squeegee tool 9 performs a printing operation, and can be supplied according to changes in printing conditions as the printing operation continues.
The mixing ratio and supply amount of 18 can be arbitrarily changed while printing operations are continued, so that a substantially constant conductive paste having a desired electrical resistance can be efficiently printed on the substrate 1.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of the present invention, FIG. 2 is a plan view with a part of FIG. 1 omitted, and FIG. FIG. 2 is a partially cutaway and enlarged front view of the device. 1: Board, 8 varnish cleaner plate, 9: Squeegee tool, 10:
Conductive paste mixing and supplying device, 1 B', 18"
: Primary conductive paste, 18: Secondary conductive paste, 2
0: variable weighing device, 21: conductive paste mixing supply device,
28: Propulsion screw, 29: Gear mechanism, 30: Clutch,
37: Kneading tool.

Claims (1)

[Claims] 1. A support for supporting a substrate to be printed, a screen plate provided facing the upper surface of the substrate supported by the support, and a press on the screen of the screen plate. In a screen printing device comprising a reciprocating squeegee tool and a conductive paste supply means for supplying a predetermined amount of conductive paste onto the screen, the conductive paste supply means has two different compositions depending on the printing operation of the squeegee tool. two variable weighing devices that supply predetermined amounts of each conductive paste, and a mixing supply device that mixes conductive pastes of two different compositions supplied from the two variable weighing devices and supplies the mixture onto a screen. A screen printing device comprising: 2. The variable weighing device comprises a container filled with conductive paste, and a pressing tool that pushes out a predetermined amount of the conductive paste in the container into the mixing supply device according to the printing operation of a squeegee. Screen printing equipment. 3. The mixing and feeding device includes a container into which conductive pastes of two different compositions are supplied from the variable weighing device, and a container with approximately the same amount as the total amount of the conductive pastes of the two compositions put into the container. Claim 1 comprising: a discharge nozzle for supplying the conductive paste in the container onto a screen; and a kneading tool located in the container for kneading and stirring the conductive paste in the container by rotation. Or the screen printing device according to item 2.