JPH0456248B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a viscous material metering and placement device.

In order to quickly place microelectronic components on a printed circuit, a device is needed to measure and place a non-conductive viscous material (adhesive) on the printed circuit between the conductive lands (raised areas) on the circuit board. (dispenser) is required. Microelectronic components are placed on this viscous material and adhered onto the plate between the conductive lands. The circuit board is then processed in a liquid soldering machine to make electrical connections between the electronic components and the conductive lands.

Existing equipment for weighing and placing viscous materials can reliably and accurately measure and place extremely small amounts of viscous paste materials in less than 1/4 second.
Even when incorporated into automatic equipment, it is obvious that it is required that the equipment not be shut down for longer than the time required to repair other movable parts within the equipment. Furthermore, all of these requirements must be met by the mechanical and electrical capabilities of the electronic component placement device itself.

Methods for arranging droplets at predetermined positions can be broadly divided into two methods: transfer methods and direct placement methods. An example of a transfer method is a rubber ink stamp, in which the liquid is deposited on a placer and then placed at the desired location. However, existing equipment for placing viscous materials on printed circuit boards by this method is not flexible in its use and must be separately designed and fabricated to suit the particular use. Generally, it is not possible to incorporate it into the program work system.

To deposit the liquid directly onto the substrate, the liquid is flowed from its reservoir into a positioner having an opening, thereby being deposited. Fluid flow from the reservoir through the conduit to the locator is accomplished by means of transfer, either by compressed air or by mechanically reducing the reservoir volume.

Also when transferring liquid by compressed air, 2
There are two methods, and a simple method is to pressurize the reservoir when the liquid is flowing, and then depressurize the reservoir once the required amount of liquid has been placed by the placement device. When applying a device that does this to relatively low-viscosity liquids, create a slight vacuum (suction back) in the storage tank when depressurizing to prevent the liquid from accidentally falling out of the placement device due to gravity or capillary action. It may prevent drooling,
In such cases, it is common to use a thin tube with a hollow blunt end in the deployer opening.

Another method uses air pressure to position liquids.
The liquid reservoir is continuously pressurized during use of the device, and liquid release is regulated by a valve located between the reservoir and the locator. The valve may be operated manually or by pneumatic, hydraulic, or other power transmission systems, but fluid must be routed through the valve lumen, and when this liquid is viscous and hardens, the valve is cleaned. It will be unable to operate during this time.

If the reservoir volume is to be reduced and the liquid moved by mechanical means, a liquid actuated plunger may be used or the reservoir may be compressed.

However, none of the above-mentioned prior art devices can produce paste-like viscous materials with a high degree of repeatability and reliability over specified time periods, such as those required for the placement of microelectronic components. It is not possible to measure minute quantities. Devices using the valves described above include a hollow needle for the placer outlet, with the viscous material projecting beyond the tip of the needle to bring the needle outlet closer to the printed circuit board substrate to release minute amounts. I am trying to place a viscous material in a desired position. In theory, the protruding material would separate from its body at the plane of the needle exit and remain on the substrate as the needle moves away. But in reality,
When the needle touches the substrate, it tends to draw liquid back into the needle outlet, and after the needle leaves the substrate, the liquid splits within the outlet, leaving a void at the needle tip, which Even in the next operation, the liquid may not be fully filled and the liquid may not be placed. Conversely, when the needle and the substrate come into contact, an excessive amount of viscous material is pushed back into the needle outlet, increasing the adhesive force between the viscous material and the inner wall of the needle, which causes viscous In some cases, the adhesion force and surface tension of the material to the substrate may be overcome, making it impossible to place the substrate. Some of these problems are overcome if the viscous material droplet is somewhat larger than the needle lumen diameter, but when metering and placing minute amounts of liquid, the droplet size should be approximately the same as the needle. the same, and for this reason hollow needle placers are unsatisfactory for this purpose.

An object of the present invention is to provide an apparatus for accurately measuring a minute amount of highly viscous paste onto a substrate such as a printed circuit board.

A second object of the invention is to have an outer cylinder held on a support and to move a viscous material metering device toward or away from the substrate to place minute amounts of viscous material on the substrate. An object of the present invention is to provide a viscous material measuring and arranging device.

A further object of the present invention is to provide a viscous material metering device that linearly arranges viscous material on a substrate without being affected by the pressure or viscosity of the viscous material.

The above objects of the invention are achieved by the metering and placement device described below.

The present invention relates to a viscous material dispensing device for rapidly placing granules (droplets) of viscous material onto a substrate, the device including a viscous material under constant pressure delivered from a viscous material source. A support housing is provided having a viscous material metering device adapted to receive the viscous material. This metering device is equipped with a mechanism for receiving a viscous material and placing it linearly on a base,
A metering and positioning mechanism in the support housing that includes the mechanism is adapted to interact with the metering mechanism to move the mechanism toward or away from the substrate. That is, the viscous material dispensing device for rapidly dispensing fine particles of viscous material onto a substrate according to the present invention comprises:
A measuring member having a bore whose tip is open and forming a measuring chamber, a measuring pin disposed in the bore of the measuring member so as to be slidable between an entering position and a retracted position, and a measuring member having a measuring member in which the measuring pin is moved to an entering position. a metering pin drive means for selectively moving the metering pin to the retracted position; a viscous material supply path that opens into the bore of the metering member when the metering pin is in the retracted position; and a viscous material supply path that supplies the viscous material to the viscous material supply path. and a viscous material supply means for introducing the viscous material into the bore of the metering member when the metering pin is retracted to the retracted position. The apparatus also includes a measuring means moving means for moving the measuring member of the viscous material measuring means between a position where the tip of the bore is close to the base body and a position where the tip of the bore is away from the base body.

A viscous material dispensing device according to yet another aspect of the present invention includes a support housing, a cylinder formed within the support housing, a double-acting piston that slides within the cylinder, and a double-acting piston that is attached to and is attached to the piston. a sleeve moved together with the piston, a metering piston slidably disposed within the sleeve, a non-wetting gland provided in the sleeve and having an axial bore, and adapted to slide within the bore of the non-wetting gland. a metering pin disposed in and movable with the metering piston; and a first fluid pressure supply selectively supplying a first fluid pressure to a chamber in the cylinder on either side of the double-acting piston to move the double-acting piston up or down. means and a second chamber in said sleeve for moving said metering piston and said metering pin in an up and down direction;
a second fluid pressure supply means for supplying a fluid pressure of;
viscous material supply means opening into a bore in the non-wetting gland below the metering pin when the metering pin is moved upwardly. Then, with the double-acting piston positioned upward, the metering pin is moved upward to open the viscous material supply means into the bore in the non-wetting gland and introduce the viscous material into the bore. , the metering pin is lowered to extrude the viscous material to the tip of the non-wetted gland, and then the double-acting piston is lowered to bring the tip of the non-wetted gland closer to the base body, and the viscous material is extruded to the tip of the non-wetted gland. is configured to adhere to a substrate.

First, a description will be given with reference to the attached FIG. 1, which shows the viscous material measuring and dispensing device when it is at rest, that is, when it is not in operation. This device measures a minute amount of viscous material between conductive lands on a printed circuit board.
Although it was developed for placing and securing extremely small electronic components to this circuit board, it can also be used for other applications where small amounts of material need to be quickly placed on a substrate. What is possible will become clear from the following explanation.

A weighing and placement device 10 is supported in a support housing 12 on an equipment frame (not shown). In the case of a small component placement mechanism, the metering and placement apparatus is to place droplets of viscous material D between conductive lands on printed circuit board 14. The support housing 12 has a cylindrical stepped cavity or lumen 16 that accommodates a viscous material placement cylinder 18 and a metering cylinder 20, both cylinders for receiving viscous material. This allows for reciprocating movement toward and away from the circuit board when placed on the circuit board.

The placement cylinder 18 is provided with a threaded cap 24 at its lower end and a piston 26 at its upper end. A lower sleeve bearing 28 is also provided within the bore 16 by a clamping pin 30 and includes inner and outer seals 32 and 34. A sleeve upper bearing 36 is also mounted within the bore 16 by a pair of clamping pins 38 and is
- sealed in lumen 16 by ring 40;

The piston 26 is connected to the bore 7 by an O-ring 42.
6 and supports a tubular housing 44 which is secured to this piston by means of a tightening nut 46. A seal 48 in the sleeve bearing 36 surrounds the tubular housing 44 to form an airtight chamber over the piston 26. The other end of the lumen 16 is sealed by a cap 50 and an annular seal 52.

The metering cylinder 20 has a piston 54 within a bore 56 of the sleeve 22.
4 has a central land 58 and both end lands 60 and 6.
2 is in place and holds the seals 64 and 66.
The lower end land 60 of the piston 54 supports a viscous material metering pin 68.

A non-wettable gland 70 is secured within the lumen 56 by a cap 72 that is in close contact with the wall and has a shoulder 74 that abuts the threaded cap 24. As can be seen, the metering pin 68 is a rigid member that extends downwardly through the lumen of the gland 70 and is in close contact with the lumen wall. A nozzle member 80 is screwed to the lower end 78 of the gland 70 as a tip.

The viscous material is delivered to the metering pin 68 by a soft elastic supply pipe 82 that communicates with a sliding portion 84 in the gland 70.
will be sent to. This rubbing part has an opening 86.
is in communication with a lumen 76, within which the metering pin 68 slides.

The viscous material supply pipe 82 communicates with a viscous material storage tank 88 which is pressurized by an air supply system 90 . Air pressure regulator 92 continues to apply the appropriate air pressure to reservoir 88 to supply viscous material to the metering cylinder at an appropriate rate. A shutoff valve 94 is also provided in the viscous material supply system.

The placement cylinder 18 is slid up and down by air supply pipes 96, 97 which communicate with the inner cavity 16 at the back of the piston 26. The piston 54 in the metering cylinder communicates with an air pipe 100 which passes through an opening 101 in the sleeve 22.
It is electrically connected to the lower end of the piston 54. In the tubular housing 44 there is an opening 102 leading to a soft elastic air supply tube 104 which applies air pressure to the upper end of the piston 54 in a defined sequence during operation of the entire device. The details will be described in the above explanation.

When the apparatus is operated from the rest state shown in FIG. 1, pressure is applied to the viscous material supply pipe 82 and the air supply pipe 100, and the piston 54 and metering rod, that is, the pin 68, are pushed up to the position shown in FIG. At this time, the viscous material enters the lumen 76 of the gland 70.
The gland 70 is made of a non-wettable material, such as tetrafluoroethylene (Teflon), which is not wetted by this viscous material.

After this operation starts, the viscous material storage tank is constantly pressurized. The amount of viscous material that enters the lumen 76 is determined by the flow characteristics and viscosity of the viscous material, the flow resistance of the viscous material in the flow path, the internal pressure in the reservoir, and the internal pressure caused by the pulling of the metering pin 68. It depends on the length of time opening 86 into cavity 76 is open. piston 5
4 and metering pin 68 are raised to advance the required amount of viscous material into lumen 76, pressurizing air supply tube 104 forces pin 68 down into lumen 76, removing the viscous material from its body. It is separated at the intersection of the lumen 76 and the opening 86. After this, the opening 86 is closed by the pin 68 and no more viscous material can enter the lumen 76. The position of the placement device at this time and the state in which the viscous material particles D are at the end of the pin 68 at the exit of the placement device are shown in FIG. Because the gland is non-wettable and the pin 68 is in intimate contact with the lumen 76, no viscous material is lost from receipt of the viscous material to the exit of the placement device.

FIG. 4 then shows that the dispensing device is depressed and
The viscous material is shown being placed on the base body 14. When the air pipe 104 is pressurized like the air pipe 98,
As the placement cylinder 18 and slave 22 are pushed downwardly through the support housing, the placement device outlet nozzle 80 contacts the substrate and the viscous material particles are forced between the pin 68 and the substrate surface. This also forces the viscous material droplet to spread out and strengthens the adhesion with the substrate, since the contact surface of this droplet with the substrate is larger than the contact surface with the pin 68. It is. Even if the viscous material comes into contact with the gland 70 during the above process, since this gland is non-wettable,
It won't stick to it.

When continuing operation of the metering and placement device, the operations shown in FIGS. 2 and 3 are repeated. That is, as seen in FIG. 4, after the viscous material particles are placed, the air tubes 96, 100 are activated to return the placement device and metering pin to the viscous material receiving position shown in FIG. In this return stroke, the bumper (buffer) 10
6 and 108 absorb and alleviate the bottoming impact of the pistons 26 and 54, respectively.

All of the above operations of the metering and placement equipment, in particular the air tubes and the viscous material reservoir pressurization source, are carried out by a computer programmed to operate each of the other elements in the equipment, here the small electronics placement machine. Governed by directives.

Furthermore, it has been found that mixing a brightening agent such as Uvitex OB into the viscous material assists in visual monitoring of work. Since the viscous material droplets are visible under dark light, the absence of previously placed viscous material particles can be detected during the next viscous material placement operation. Automatic detection is also possible by numerically reading the bright patterns created by droplets on the substrate.

Thus, the viscous material placement apparatus described above quickly and linearly places viscous material droplets from the lumen 76 of the gland 70 onto the substrate 14. The amount of viscous material that flows into lumen 76 depends on the flow characteristics and viscosity of the material, the flow resistance of the inlet path, the air pressure in the viscous material reservoir, and the duration of continuity between outlet 86 and lumen 76. It is determined. Since the properties of the viscous material, flow system resistance, and reservoir pressure are constant for a particular system configuration, controlling the length of time that the outlet 86 of the feed line 82 is open (for rapid actuation of the metering pin 68) Therefore, the amount of viscous material that enters the lumen 76 is regulated, and thus the amount of viscous material placed on the substrate is determined.

[Brief explanation of drawings]

FIG. 1 shows a side view of a viscous material dispensing device according to the invention when not in operation. 2 is a side view of the device shown in FIG. 1 when the metering pin is pulled up to receive a metered viscous material; FIG. Figure 3
4 is a side view of the metering pin reaching its lowest point after receiving the viscous material in the apparatus, and FIG. FIG. 3 is a side view when arranged. 88... viscous material storage tank, 86... viscous material lumen 7
Inlet of 6, 76...Inner cavity of gland 70 on which metering pin 68 slides, 22...Sleeve, 70...
...non-wettable gland, 26... piston for placement,
54...Measuring piston, D''...Viscous material droplet.

Claims (1)

[Scope of Claims] 1. A viscous material dispensing device for quickly distributing fine particles of viscous material onto a substrate, comprising: (a) a measuring member having a bore whose tip is open and forming a measuring chamber; b) a metering pin disposed within the bore of the metering member so as to be slidable between an advanced position and a retracted position; (c) selectively moving the metering pin between the advanced position and the retracted position; (d) a viscous material supply channel that opens into the bore of the metering member when the metering pin is in the retracted position; (e) a viscous material supply channel that moves the viscous material into the viscous material supply channel; a viscous material supplying means that causes the viscous material to be introduced into the bore of the measuring member when the measuring pin is retracted to the retracted position; and viscous material measuring means comprising: , comprising a measuring means moving means for moving the measuring member of the viscous material measuring means between a position where the tip of the bore is close to the base body and a position away from the base body. , viscous material dispensing equipment. 2. The device according to claim 1, further comprising a non-lubricated gland attached to the metering member, the metering pin being configured to pass through the gland. 3. A viscous material dispensing device for rapidly dispensing granules of viscous material onto a substrate, comprising: (a) a support housing; (b) a cylinder formed within said support housing; and (c) within said cylinder. (d) a sleeve attached to and moved with said piston; (e) a metering piston slidably disposed within said sleeve; (f) a metering piston slidably disposed within said sleeve; a non-wetting gland provided and having an axial bore; (g) a metering pin disposed to slide within the bore of the non-wetting gland and movable with the metering piston; (h) the double-acting first fluid pressure supply means for selectively supplying a first fluid pressure to chambers in the cylinder on both sides of the piston to move the double-acting piston up and down; (i) the metering piston and the metering pin; A second chamber is inserted into the sleeve within the sleeve so as to move the
(j) viscous material supply means opening into the bore in the non-wetting gland below the metering pin when the metering pin is moved upwardly; , with the double-acting piston positioned upwardly, the metering pin is moved upward to open the viscous material supply means into the bore in the non-wetting gland to supply the viscous material to the into the bore, lowering the metering pin to force the viscous material to the tip of the non-wetting gland, and then lowering the double-acting piston to bring the tip of the non-wetting gland closer to the substrate. A viscous material dispensing device characterized in that the viscous material extruded to the tip of a lever is attached to the base body. 4. The apparatus of claim 3, wherein the viscous material supply source is a constant pressure viscous material reservoir.