EP2695506A1

EP2695506A1 - Method and fluid transfer unit having squeegees for providing a smooth surface of fluid

Info

Publication number: EP2695506A1
Application number: EP12718110.5A
Authority: EP
Inventors: Martin Dahlberg
Original assignee: Micronic MyData AB
Current assignee: Micronic MyData AB
Priority date: 2011-04-08
Filing date: 2012-04-04
Publication date: 2014-02-12
Also published as: WO2012136733A1

Abstract

A method and apparatus for applying mounting a mixture, solution or flux to an electronic component in an electronic component mounting apparatus. The method and apparatus includes a plate (200) with cavities (206) of various sizes. The cavities are filled with a viscous molding mixture, solution or flux as electronic component are dipped into the cavity such that a portion of the component is wetted with the mounting solution or flux. The cavities can be filled with a number of different types of solution or flux. The method and apparatus can include a squeegee (202, 204), scraper or blade that is run across the surface of the plate along the rim that defines the opening of the cavity, thereby displacing mixture, solution or flux out of the cavity such that a smooth and uniform surface is created within the cavity. The method and apparatus can include any number of blades. The blades can be angled such that the mixture, solution or flux is pushed in a direction that is relatively perpendicular to the direction in which the blades are moved across the surface of the plate. The blade can be mounted at off-setting positions such that the blades displace the trail of solution or flux that spills out of the path of movement of the other blade.

Description

METHOD AND FLUID TRANSFER UNIT HAVING SQUEEGEES FOR PROVIDING A SMOOTH SURFACE OF FLUID

[0001] This application is related to and claims the benefit of U.S. Prov. App. No.

61/473,659, filed 8 April 2011, entitled "Method and Fluid Transfer Unit Having Squeegees for Providing a Smooth Surface of Fluid," by Martin Dahlberg..

BACKGROUND

[0002] Electronic component mounting apparatuses are used to mount electronic components speedily and correctly to electronic circuit boards, with improving mounting quality.

[0003] A conventional electronic component mounting apparatus typically comprises a board transfer device for carrying in and out circuit boards, a front component feed device and a rear component feed device each having a plurality of component feed units, a head part with a mechanism that can load desired suction nozzles, move up and down, and rotate the loaded suction nozzles, a board recognition camera, an XY robot movable in X and Y directions, a fluid or solvent transfer unit, and an electronic component image pickup device.

[0004] The conventional electronic component mounting apparatus operates generally in a manner as follows. The board transfer device transfers the circuit board to a mounting position. The XY robot moves the board recognition camera over the circuit board. The camera determines the positions where electronic components are to be mounted on the circuit board. The XY robot then moves the board recognition camera over the front component feed device and the rear component feed part and recognizes the components that need to be picked and mounted into the previously detected positions. A component mounting apparatus is illustrated in WO 2011/079956.

[0005] Subsequently, the nozzles are activated and the electronic components are picked as the nozzles create a suction force which holds the desired component to the nozzle. The picked components are then further moved to the fluid or solvent transfer unit, where the components are moved such that the flux is transferred to the components. Typically, the prior art has used large reservoirs of flux or solution in which a portion of the component is dipped into in order to wet the component with the solution, flux or granular paste. Altitudes of the electronic components held by the nozzles may be imaged by the component image pickup device and measured, thereby judging the result. When the measured result of the held attitudes and/or altitudes of the components is normal, the components are corrected in position on the basis of the obtained image information. The XY robot then moves to the desired positions above the circuit board and the electronic components are mounted onto the circuit board. [0001] This application is related to and claims the benefit of U.S. Prov. App. No.

BACKGROUND [0002] Electronic component mounting apparatuses are used to mount electronic components speedily and correctly to electronic circuit boards, with improving mounting quality.

[0005] Subsequently, the nozzles are activated and the electronic components are picked as the nozzles create a suction force which holds the desired component to the nozzle. The picked components are then further moved to the fluid or solvent transfer unit, where the components are moved such that the flux is transferred to the components. Typically, the prior art has used large reservoirs of flux or solution in which a portion of the component is dipped into in order to wet the component with the solution, flux or granular paste. Altitudes of the electronic components held by the nozzles may be imaged by the component image pickup device and measured, thereby judging the result. When the measured result of the held attitudes and/or altitudes of the components is normal, the components are corrected in position on the basis of the obtained image information. The XY robot then moves to the desired positions above the circuit board and the electronic components are mounted onto the circuit board.

[0006] Transferring the solution or flux to the components such that the components are wetted and can subsequently be mounted onto the circuit board poses many challenges. Of particular concern is that the proper amount of solution or flux is uniformly applied to the component to ensure that the component can be mounted onto the circuit board. This challenge is further intensified as the mounting apparatuses must be capable of transferring solution or flux to a large number of components in a quick amount of time in order to efficiently manufacture the electronic devices in a cost effective manner.

[0007] Furthermore, often times components require different solutions or fluxes in order to be mounted onto the circuit board, thus there are problems with adapting systems that are capable of supporting and applying numerous different types of solutions and fluxes.

Additionally, owing to environmental concerns, smaller component sizes and overall advances in the fields of the electronic component technologies, the solution or flux that is actually applied and used to mount the components has advanced to include complex mixes that use highly engineered materials. As a result, the solutions and flux themselves have increased in cost.

Therefore, there is the further problem of applying the solutions to components such that the amount of solution or flux that is wasted in the application process is minimized. There therefore exists a need for solution or flux application methods and apparatuses that allow for the efficient application of the solution or flux to electronic components that minimizes the amount of solution or flux that is wasted but still ensures that the proper amount of solution or flux is applied.

SUMMARY

[0008] A method and apparatus for applying solution or flux to components for mounting the components to a circuit board within a component mounting apparatus. The disclosed technology includes at least one cavity within a plate. The cavity contains a solution or flux that is used to mount the electronic component. A squeegee or scraper is run across a portion of the plate and the opening of the cavity defined by a rim to ensure that a uniform and smooth solution or flux surface is created at a certain target level within the cavity, e.g. at a consistent and repeatable height within a certain acceptable range. Furthermore, as the squeegee or scraper remains in contact with the rim of the cavity, the desired depth is obtained in a precise manner without the need for solution or flux surface height measurements. As the height of the surface of the solution or flux can be controlled within the cavity, the component simply can be pushed into the cavity such that it makes contact with the bottom of the cavity thereby achieving sufficient wetting of the component so that it can be securely mounted. In specific instances, the solution or flux is dispensed into the cavity and the squeegee is run across the opening of the cavity such that a target percentage of the cavity's volume contains the flux or solution.

[0009] Alternatively two squeegees or scrapers can be positioned at off-set positions on opposing sides of the cavity to further ensure that a uniform and smooth surface of solution or flux is created inside the cavity at a certain level above the bottom of the cavity. The squeegees or scrapers can be angled such that the solution or flux that the squeegee or scraper pushes is displaced in a direction that is angled to the movement of the squeegees or scrapers. As a result, the solution or flux is contained within the area that the squeegees cover and some of the solution or flux can be pushed further away from the cavity, thereby further ensuring that a smooth and uniform surface of solution or flux is created within the cavity at a consistent and repeatable level above the bottom of the cavity. Alternatively, the squeegees or scrapers can be angled such that the solution or flux is pushed toward the cavity such that the excess solution or flux that the squeegees move out of the cavity in creating a uniform surface is pushed back into the cavity. This minimizes the amount of wasted solution or flux.

[0010] Certain aspects of the invention may be described by a method performed prior to transferring a small amount of a fluid, e.g. flux or solution, to at least one electronic components by dipping the at least one electronic component into a cavity containing the fluid. The method is defined by the actions of first moving a blade, or a pair of blades, across the rim of the cavity containing the fluid from a first position to a second position on the rim, and where the at least one blade is having at least one wiping surface that is configured to make contact with a surface of a plate or container and span the upper opening, whereby the at least one blade is moving certain small amounts of the fluid away from and into the cavity in a concurrent action, such that a smooth fluid surface is created in the cavity at a target height level above the bottom of the cavity, and wherein the smooth fluid surface is created at the target height level within a deviation range of a few percent from the target height level.

[0011] The cavity may be of a size that is adapted for a specific type of component, or types of components, that is picked and mounted onto the circuit board. Specifically, the cavity can be of a depth to ensure that a component of a specific height is adequately coated such that it can be mounted onto the board properly. The plate can have multiple cavities of various sizes to fit components of various sizes that are mounted onto the circuit board. The multiple cavities can also contain different solutions or flux depending on the component that such cavities are used to coat.

[0012] Alternatively, the squeegees or scrapers of a pair of squeegees or scarpers can be configured to be in mutually off-set positions, such positions being different along an axis that is perpendicular to the moving direction of the squeegees or scrapers. By positioning the squeegee or scarpers in mutually off-set positions along the axis perpendicular to the moving direction of the squeegees or scrapers, the excess solution or flux that flows out from the path of the squeegee or scraper flows into the path of the other squeegee or scraper. The other squeegee or scraper then moves the excess solution of flux that flows out from the first squeegee or scraper such that the excess solution or flux is kept on the plate. As such, this ensures that a maximized amount of excess solution or flux is kept on the plate. Such excess solution or flux can be used to refill the cavity and thus the amount of solution or flux that is wasted during operation of the apparatus is minimized.

[0013] The off-setting of the position of the two scrapers along the axis that is perpendicular to the moving direction, may also be used to keep or hold apart different solutions or flux associated with different cavities, i.e. two different types of fluids associated with different cavities are not mixed, while at the same time avoiding or mitigating the waste of fluid, e.g. solution and/or flux, by moving the excessive amounts of fluid(s) from one side of a portion of the total span width to the other side of said portion of the total span width, where the total span width is the span width the pair of off-positioned scrapers cover perpendicular to the moving direction of the scrapers. Any number of different squeegees or scrapers can operate independently and be used to create a smooth fluid surface within any number of cavities at a consistent and repeatable height within each cavity. The plate can be used to mount components simultaneously within the component mounting apparatus that require different solutions or flux types in order to mount the various components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a cross sectional view of the solution or flux within the cavity after an electronic component is dipped into it.

[0015] FIG. 2 is a cross sectional view of a BGA electronic component being dipped into the solution or flux.

[0016] FIG. 3 is a cross sectional view of the solution or flux within the cavity after the

BGA electronic component has been dipped into the solution or flux.

[0017] FIG. 4 is a plain view of an example plate of the invention with cavities of various sizes.

[0018] FIG. 5a is a cross sectional view of the solution or flux within the cavity after an electronic component is dipped into the solution or flux and before the squeegee or scraper is moved across the cavity.

[0019] FIG. 5b is a cross sectional view of the solution or flux within the cavity as the squeegee or scraper is moved across the cavity.

[0020] FIG. 5c is a cross sectional view of the solution or flux within the cavity after the squeegee or scraper is moved across the cavity

[0021] FIG. 6 is a plain view of an example plate with two squeegee or scrapers. [0022] FIG. 7 is a plain view of an example plate that shows the movement of two squeegees or scrapers over the same cavity wherein the squeegees or scrapers are mounted in off-set positions on opposing sides of the cavity.

[0023] FIG. 8 is a plain view of an example plate that shows the operation of the two squeegee or scraper configuration shown in FIG. 7.

[0024] FIG. 9 is a plain view of an example plate that shows a two squeegee

configuration for a plate with cavities that contain two different types of flux.

DETAILED DESCRIPTION

[0025] In operation of an electronic components mounting apparatus, a nozzle is used to pick up the components that are to be mounted. The mounting apparatus can include a holding member with two nozzles that are attached such together, such that each nozzle picks up an electronic component and the picked up electronic components move around simultaneously together as the two attached nozzles are moved around the electronic component mounting apparatus. The nozzle with the attached component is then moved to the flux transfer unit whereby a mixture, solution or flux is applied to the component. Alternatively, a component image pickup device can be used to determine the positioning and placement of the component within the nozzle. This allows the component to be placed at the appropriate depth within the cavity such that the component is adequately wetted and can be mounted securely. Such image pickup device, in turn accounting for the variety of positions in which components are held within the nozzle. The mixtures, solution or flux can be any solution or paste that wets a portion of the electronic component and subsequently is used to secure the component to the circuit board when the electronic component is mounted. The mixture, solution or flux is viscous in that it has the property of being thick, such that it is resistant to forces that are exerted upon it. The solution can include solder balls that are contained within a flux that further increase the viscosity of the solution. By way of example, the solution can be a solder paste that includes balls of solder within a flux. After the electronic component is wetted such that a portion of the component is covered in the solution or flux, the electronic component is moved towards the specific region of the circuit board in which it is suppose to be mounted. The nozzle then positions the electronic component at the desired location on the circuit board and releases the electronic component. After the wetted component is positioned and released onto the circuit board, heat is applied thereby causing the solder paste to form a solder joint that secures the electronic component to the circuit board. The process of wetting electronic components and positioning them on the circuit board can be repeated until every component on the board is positioned on the board and secured upon it. [0026] FIGs. 1-3 illustrate some problems encountered with wetting components in solution transferring techniques. FIG. 1 shows the solution or flux within the trench after an electronic component has been dipped, forming a non-uniform surface along the top of the solution or flux within the cavity. Owing to the viscous nature of the solution or flux, gas bubbles are formed within the solution or flux after the component is placed into the solution or flux. FIG. 2 shows the placement of a ball grid array (BGA) type electronic component into the solution or flux. FIG. 3 shows that after the BGA component is removed, due to the viscous nature of the solution or flux, the surface of the flux is non-uniform and vacancies in the solution are created that can extend to the bottom of the cavity. It is clear, such non-uniform solution or flux surface and the gas bubbles that are formed within the solution or flux lead to incomplete wetting of the components that are subsequently dipped into the solution or flux. Thus the solution transferring is ineffective.

[0027] The prior art dips the components into large reservoirs of mixtures, solution or paste in order to wet the components with such mixture, solution or waste. Such large reservoirs take up large amounts of space within the flux application unit of the electronic component application apparatus. Therefore the design is not suited for simultaneously using multiple types of mixture, flux or solution in various regions within the flux application unit.

[0028] The use of smaller cavities that match the size and dimension of the electronic components that are dipped into a particular cavity, as described by the invention, allows for greater design flexibility and the more efficient mounting of different electronic components using various types of mixture, solution or flux.

[0029] FIG. 4 shows a planar view of a plate 100, according to the invention, with cavities of various sizes 102, 104 and 106. The plate is part of the mixture, flux or solution transfer unit of the electronic components mounting apparatus. The plate 100 can be composed of any material that is capable of containing a solder or flux material at the operating

temperatures at which the electronic components mounting apparatus is operated at. The plate includes one or more cavities 102, 104 and 106 that can be of the same size or various sizes as is shown in FIG. 4. The cavities can be formed within the plate using any suitable method, including but not limited to press forming. The plate can contain any number of cavities of various sizes as is required for the size and number of components that are mounted onto the circuit board. The plate is part of the solution transfer unit of the electronic components mounting apparatus. The solution transfer unit can contain any number of plates that are necessary to provide cavities of various sizes containing the solution or flux that is applied to various electronic components. [0030] A mixture, solution or flux is dispensed into the cavities within the plate. As is described in the operation of the apparatus, the nozzle moves the electronic components to the cavities and moves downward such that a portion of the electronic component is submerged in the mixture, flux or solution that is contained within the cavity. The electronic components are submersed to a depth such that a portion of the electronic component is wetted with the mixture, solution or flux and can be subsequently mounted and secured onto the circuit board. The solution or flux can be dispensed into the cavities and squeegees or scrapers can be run across the opening of the cavity such that the surface of the solution or flux is at a certain target height with respect to the sidewalls of the cavity.

[0031] By way of example and given a certain type of fluid, e.g. a certain first type of mixture, flux or solution with a certain viscosity, the squeegees or scrapers may be configured to create a smooth fluid surface at a predetermined target height level within a particular first cavity which is always within a consistent and repeatable distance range of e.g. 85 to 87% of the total height of the cavity from a position at the bottom of the cavity to the surface or rim of the cavity, or the fluid surface may e.g. be kept above or below a predetermined target height level of 85% of the distance from the bottom of the cavity to the surface or rim of the cavity within a deviation of a few percent from the target height level. By further way of example and given a different type of mixture, flux or solution having a viscosity level different from the first type of mixture, flux or solution, the same squeegees or scrapers, or pair of scrapers, may be configured such that e.g. 89.5 to 90.5% of a certain other second cavity's volume is always filled with the solution or flux after each scraping action. The volume percentage of the cavity that contains solution or flux after the squeegee or scraper, or pair of scrapers, is run across the opening of the cavity depends on a number of factors, including the dimensions of the cavity and the viscosity level of the mixture, solution or flux.

[0032] This is advantageous in that the nozzle, carrying the electronic component, does not have to be adjusted and moved further downward within the cavity in order to submerge the same desired portion of the electronic component after each successive wetting of multiple electronic components without measuring the height of the surface of the solution or flux within the cavity. This is also advantageous, in that the height of the surface of the solution or flux can be formed at a level within the cavity whereby the electrical component simply needs to be placed into the cavity such that the electrical component makes contact with the bottom of the cavity, without having to precisely control the height at which the nozzle dips the component into the cavity. Optionally, the control of the height of the surface of the flux allows the component to be dipped into the cavity to a level such that the desired portion of the component is wetted without having to measure the height of the surface of the solution or flux and without the component contacting the bottom of the cavity. This is advantageous in that many of the electrical components that are dipped are fragile and therefore limiting contact with the bottom of the cavity limits the amount of damage that the component receives during the fluid transfer process.

[0033] The use of multiple cavities of differing sizes within the plate according to the invention allows for mixtures, solutions or fluxes of various types to be dispensed into the various cavities. The various cavities can contain different mixtures, solutions and flux that are unique and tailored for mounting a specific component of multiple types of different components onto the circuit board. The component mounting machine apparatus can be programmed and automated to dip a specific component into a cavity that contains one type of mixtures, solution or flux and dip a different component into a cavity that contains another type of mixture, solution or flux.

[0034] The cavities of the invention can be of any size or dimension. In some instances, the cavity can be of a size and/or dimension that corresponds to a specific component that is to be mounted on the circuit board, or the size and/or dimension of a plurality of types of components to be mounted on the circuit board. Specifically, the cavity can be of a certain depth and have a specific footprint that corresponds to the size and footprint of the specific component such that a portion of the component is wetted when partially submersed within the mixture, solution or flux. By making a cavity that is of a specific size that corresponds to the specific component, the need for large troughs containing mixture, solution or flux is reduced. This in turn reduces the amount of mixture, solution or flux that is wasted as the cavities that are tailored to accommodate a specific size of a component are generally smaller than the large troughs that are used by the prior art. Therefore, after the circuit boards are constructed, the cavity contains much less excess solution or flux than a large trough or reservoir, and subsequently the amount of wasted mixture, solution or flux is reduced.

[0035] FIG. 5a shows a section view of the solution transfer apparatus 500 with a squeegee or scraper 502 before the squeegee or scraper is moved through the cavity 504 across the surface 506 of the contained solution or flux 512. As is seen in the figure, the surface of the contained solution or flux is non-uniform and the solution or flux has gas bubbles within the volume. Such non-uniform surface and gas bubbles are caused by the dipping of an electronic component into the solution or flux that is contained within the cavity 504. The result of the nonuniform surface and gas bubbles is that electronic components that are subsequently dipped into the solution or flux are not sufficiently wetted so that the electronic component can not be securely mounted. In order to ensure that the next electronic component is wetted such that the component can be securely mounted, a uniform solution or flux surface is created and the gas bubbles are removed using a squeegee or scraper. A volume of excess solution or flux 508 is pushed by the squeegee or scraper 502 as the squeegee or scraper is moved towards the cavity. The volume of excess solution or flux 508 that is pushed by the squeegee or scraper moves in a rolling wave like motion 510 as the volume of excess solution or flux is pushed towards the cavity.

[0036] FIG. 5b shows a section view of the solution transfer apparatus 500 as the squeegee or scraper 502 is moved across the cavity 504. The squeegee or scraper is of a length that is greater than the distance between opposing ends of the upper rim 503 of the cavity that defines the opening of the cavity such that the squeegee or scraper simultaneously makes contact with the rim 503 on opposing sides of the cavity. The squeegee or scraper 502 pushes a portion of the volume of excess solution or flux back into the cavity 504. As such the excess solution or flux is used to coat an electronic component, thereby minimizing the amount of solution or flux that is wasted throughout the component mounting process. As the squeegee or scraper moves across the upper rim 503 of the cavity, the squeegee or scraper pushes a volume of solution or flux back into the cavity, such that it mixes with the solution or flux within the cavity. Due to the viscosity of the solution or flux a portion of the volume of solution or flux remains in contact with the squeegee or scraper as it is moved across the rim of the cavity. Such contact with the squeegee or scraper causes the solution or flux within the cavity to move in a wave like motion 516, thereby causing gas bubbles within the solution or flux to move to the surface and subsequently escape from the solution or flux. The removal of such gas bubbles, as discussed previously, is advantageous in that the electronic component that is subsequently dipped is wetted such that it can be securely mounted. Furthermore, the movement of the solution or flux in a wave like motion causes the solution of flux to move such that a smooth and uniform fluid or solution surface 514 is created at a desired level within the cavity. As with removal of the gas bubbles, the creation of a smooth fluid or solution surface is advantageous in that the electronic component that is subsequently dipped is wetted such that it can be securely mounted.

[0037] FIG. 5c shows a section view of the solution transfer apparatus 500 after the squeegee or scraper 502 is moved across the cavity 504 that contains the solution or flux 512. The squeegee of scraper pushes a volume of excess solution or flux 518 outside of the cavity 504. Such excess solution or flux 518 can then be pushed back into the cavity by another blade concurrently with the blade moving out a new volume of excess solution or flux out of the cavity. As is shown, the gas bubbles are removed from the solution or flux 512. Furthermore, a smooth and uniform solution or flux surface 514 is created within the cavity. The creation of a smooth and uniform solution or flux surface and the removal of the gas bubbles within the flux both is advantageous in that an electronic component that is subsequently dipped into the solution of flux is wetted such that it can be securely mounted. Furthermore the squeegee can be used to control the amount of solution or flux that is within the cavity by scraping away solution or flux from within the cavity such that the desired amount of solution or flux is left within the cavity. Using the squeegee or scraper to scrape away solution or flux such that a constant volume of solution or flux within the cavity helps to realize the creation of a height of the surface of the solution or flux at the same relative position with respect to the walls of the cavity after more solution or flux is dispensed into the cavity. As a result, subsequent electronic components do not need to be dipped to various depths within the cavity in order for the component is adequately coated such that it can be securely mounted. Furthermore, the height of the surface of the solution or flux within the cavity can be controlled, such that in order to dip the electrical component to a desired depth, the electrical component simply needs to be placed into the cavity such that it makes contact with the bottom of the cavity. Optionally, the control of the height of the surface of the flux allows the component to be dipped into the cavity to a level such that the desired portion of the component is wetted without having to measure the height of the surface of the solution or flux and without the component contacting the bottom of the cavity. This is advantageous in that many of the electrical components that are dipped are fragile and therefore limiting contact with the bottom of the cavity limits the amount of damage that the component receives during the fluid transfer process.

[0038] This drastically reduces the difficulty of manufacturing as all components of the same type simply need to be dipped to the same depth without calculation of the dipping depth based upon the level the surface of the solution or flux.

[0039] FIG. 6 shows a view of the plate 200 of a fluid transfer apparatus with two squeegees or scrapers 202 and 204. The plate includes a cavity 206, in which the mixture, solution or flux is contained within. As discussed previously, the cavity can contain a mixture, solution or flux and a scraper or squeegee can be run across the cavity in order to create a uniform and smooth surface of the solution or flux contained within the cavity. The squeegee or scraper creates a smooth and uniform surface of solution within the cavity at a specific height within the cavity. A camera can be used to determine the height of the electronic component, and therefore determine how much the nozzle holding the component needs to be moved such that a portion of the electronic component is wetted with the mixture, solution or flux. This ensures that the proper amount of mixture, solution or flux is applied to the components such that a strong bond is formed during mounting and the electronic component remains securely attached to the circuit board.

[0040] The squeegees or scrapers 202 and 204 can be angled with respect to the directions 208 and 210 in which the squeegees or scrapers move. Angling the squeegee causes the flux or solution that is displaced to be pushed in a direction that is angled to the axis formed by the directions 208 and 210 in which the squeegees or scrapers move. After displacing the excess mixture, solution or flux the squeegee or scraper can be lifted away from the surface of the plate such that the squeegee or scraper no longer makes contact with the plate. The squeegee or scraper is then moved back to its initial starting position and lowered back onto the plate so that the squeegee or scraper can be moved across the opening of the cavity to displace any excess mixture, solution or flux away from the cavity again. As the first squeegee is raised a second squeegee is lowered to the plate. The second squeegee moves across the cavity along the same path of the first squeegee in the opposing direction. This causes the mixture, solution or flux that was pushed by the first squeegee to be pushed back across the cavity and the plate. As a result, the excess mixture, solution or flux is contained within a specific area of the plate surrounding the cavity and the solution or flux is pushed back into the cavity such that it refills the cavity after an electronic component is dipped into the solution within the cavity. This minimizes the amount of solution or flux that is used and wasted during the electronic component mounting process.

[0041] The transfer unit 200 can include, as is shown in FIGs. 6 and 7, two squeegees

202 and 204. The squeegees or scrapers 202 and 204 move along directions 208 and 210 across the cavity 206. The movement of the squeegees or the scrapers across the cavity displaces solution or flux within the cavity such that a smooth and uniform surface is created within the cavity at a consistent position relative to the wall of the cavity. As the squeegee or scraper moves across the plate pushing solution or flux with it, a line of excess solution or flux 220 may form as the pushed solution or flux moves down and out of the path of the moving squeegee or scraper. As shown in FIG. 7, the second squeegee or scraper 204 can be positioned at an off-setting position with respect to the first scraper 202. Such off-setting position is realized through the mounting of the second squeegee or scraper 204 at a different position than the first squeegee or scraper 202 along the axis that is perpendicular to the directions in which the squeegee or scrapers 202 and 204 move. As a result, the line of excess solution or flux 220 that was formed by the excess solution or flux flowing out of the path of the first squeegee or scraper is in the path of the second squeegee or scraper. Therefore, the movement of the second squeegee or scraper gathers and moves the solution or flux from the line of excess solution or flux such that it is confined within a portion of the plate and can be subsequently reused. This reduces the amount of solution or flux that is wasted during the component mounting process.

[0042] The squeegees or scrapers can be coupled together such that the movement of one squeegee or scraper is dependant on the movement of the other squeegee or scraper. Through such dependence, the squeegees or scrapers move simultaneously in the same directions back and forth over the opening of the cavity. Each squeegee or scraper serves to displace the mixture, mixture, solution or flux such that a smooth surface is created within the cavity.

[0043] After each squeegee or scraper is moved along the corresponding directions across the cavity, the squeegee or scraper can be then lifted away from the panel such that the squeegee or scraper does not make contact with the top surface of the panel. The squeegee or scraper is then moved back to its original starting position where it is lowered so that it once again makes contact with the top surface of the panel. The squeegee or scraper is then pushed once again in the same direction across the top surface of the panel over the opening of the cavity, as the process repeats itself. The squeegee or scrapers 202 and 204 can operate sequentially such that as one of the squeegee or scrapers is being lifted and returned to its starting position, the other squeegee is moved across the panel, over the opening of the cavity, displacing any excess mixture, solution or flux.

[0044] Both squeegees or scrapers 202 and 204, as are shown in FIGs. 6 and 7, can be angled with respect to the directions 208 and 210 in which the squeegees or scrapers move along. As discussed previously, angling the squeegee or scrapers causes them to push the excess mixture, solution or flux in a direction that is relatively angled to the axis formed by the directions in which the squeegees or scarpers move. FIG. 8, illustrates a plan view of the plate and two angled squeegee or scraper configuration in operation. The movement of excess mixture, solution or flux in response to the movement of the squeegees or scrapers is illustrated. As squeegee or scraper 310 is moved along the direction 314, the volume of mixture, solution or flux 302 is pushed in direction 306 that is angled to the direction 314 in which the squeegee or scraper 314 is moved. Similarly, as squeegee or scraper 312 is moved along direction 316, the volume of mixture, solution or flux 304 is pushed in direction 308 that is angled to the direction 316 in which the squeegee or scraper 312 is moved along. As shown in FIG. 8, the opposing squeegees or scrapers 310 and 312 are positioned on opposite sides of the cavity and can be angled such that the squeegees or scrapers 310 and 312 are roughly parallel. As the squeegees or scrapers 310 and 312 are angled such that they are roughly parallel, the directions 306 and 308 in which the corresponding squeegees or scrapers displace the mixture, solution or flux are opposite. Therefore, the squeegees or scrapers 310 and 312 contain the solution of flux within a specific area of the plate surrounding the cavity such that the solution or flux can be pushed back into the cavity and subsequently reused.

[0045] FIG. 9 shows a plan view of a plate with two cavities containing two different types of mixture, solution or fluxes, and two angled squeegees or scrapers to create a smooth and uniform surface of solution or flux within each cavity. The two cavities 402 and 404 contain two different types of mixture, flux or solution to allow for, as previously described, the simultaneous and more efficient mounting of two different components that utilize two different mixtures, solutions or fluxes in order to be mounted onto the circuit board. Squeegees or scrapers 406 and 408 are moved in corresponding directions 410 and 412 so that a smooth mixture, solution or flux surface is created over the top openings of the cavities 402 and 404. The squeegees or scrapers 406 and 408 are angled to push the excess flux 414 and 416 of the two different mixture, solution or flux types along directions 418 and 420. Such directions 418 and 420 are angled with respect to the directions 410 and 412 in which the squeegees or scrapers are moved. Therefore, the mixture, solution or flux of two different types 414 and 416 are displaced not only away from the cavities but also away from each other so that the two types of mixture, solution or flux do not mix. Thus, the efficiency of the mounting apparatus is improved as the two different types of mixture, solution or flux do not mix together, such that they can be used again and reintroduced into the respective cavities. Similarly two pairs of squeegees or scrapers can be used, one pair for each cavity in order to further limit the different mixture, solution or flux types do not mix together and that the flux or solution of each type is pushed towards the cavity and subsequently reused.

PARTICULAR IMPLEMENTATIONS

[0046] In one implementation, a fluid transfer unit for an electronic component mounting apparatus is provided. The fluid transfer unit includes a container with a cavity that contains a volume of a fluid. The cavity has an upper opening that is defined by a generally horizontal rim. The fluid transfer unit includes a blade that has a wiping surface that is configured to make contact with the surface of the container and further to be movable over the rim of the cavity to span the upper opening at a fixed point of one end of the rim. The blade is engaged with a blade driver that causes the blade to move in a movement of direction from a first position to a second position on the opposite end of the rim. The movement of the blade causes the blade to displace a volume of fluid from the cavity thereby creating a smooth fluid surface in the cavity at a height above the bottom of the cavity, such that an electronic component can be dipped into the fluid through the smooth fluid surface. In one implementation, the displacement of a volume of fluid from the cavity causes the creation of a fluid surface at a consistent and repeatable height above the bottom of the cavity. In one implementation, the cavity is of a size such that electronic components of a specific size can be dipped into the fluid. Furthermore in one implementation, the blade can be angled with respect to the direction of motion of the blade such that it displaces a volume of fluid in a direction that is angled with respect to the direction of motion of the blade.

[0047] In one implementation, the fluid transfer unit includes a second blade that has a wiping surface and is placeable against the rim to span the opening at a fixed point of one end of the rim. The second blade is also engaged by the blade driver for movement in the opposite direction as the first blade from a third position to a fourth position on an opposite end of the rim. The movement of the second blade causes the second blade to displace a volume of fluid such that a smooth fluid surface is created in the cavity at a consistent and repeatable height. The first blade can be configured to displace a volume of liquid to a first location on the container away from the cavity, and the second blade can be configured to displace a volume of liquid to a second location on the container away from the cavity, wherein the first location is different from the second location.

[0048] In one implementation, the first blade is mounted at a first site and the second blade is mounted at a second site, the site of the first blade being off-set from the site of the second blade along an axis that is perpendicular to the direction of motion of the first and second blades. In one implementation, the smooth fluid surface is created at a height within the cavity that is in a range of 79% to 81% of a total height of the cavity. In another implementation, a range of 89.5% to 90.5% of a total volume of the cavity contains fluid.

[0049] In one implementation, the fluid transfer unit includes a second cavity that is separate from the first cavity and having an upper opening defined by a generally horizontal rim, the cavity containing a volume of fluid. The fluid transfer unit includes a second blade that has a wiping surface that is configured to make contact with the surface of the container and further configured to be movable over the rim spanning the opening of the second cavity at a fixed point of one end of the rim. The second blade driver engages the second blade causing the second blade to move from a first position on the rim of the second cavity to a second position on an opposite end of the rim of the second cavity. Such movement of the second blade causes the blade to displace a volume of fluid out of the second cavity, such that a smooth fluid surface is created in the cavity at a height above the bottom of the cavity, such that the electronic component can be dipped through such surface. The first and second cavity can contain a different type of fluid such that the first cavity contains a first type of fluid and the second cavity contains a second type of fluid. In one implementation, the second cavity can be of a size that is configured for the dipping of a second component of a second specific size into the cavity. In one implementation, the second blade displaces a volume of liquid from the second cavity such that the surface of the liquid is created at consistent and repeatable height above the bottom of the cavity. In one implementation, the smooth fluid surface is created at a height within the second cavity that is in a range of 91,4% to 92,2% of a total height of the second cavity. In another implementation, a range of 79% to 85% of a total volume of the second cavity contains fluid.

[0050] In one implementation, the fluid transfer unit further comprises a component holding member. The component holding member can include two vacuum nozzles with which two electronic components can be picked up at the same time and simultaneously dipped into the fluid contained within the cavity. In one implementation, the fluid transfer unit further comprises a component image pickup device. The component image pickup device can be configured to measure the height of an electronic component that is held by the component holding member, such that position to which the component holder needs to be moves such that the electronic component is dipped into the cavity to a level in order to wet the portion of the electronic component with fluid can be determined.

[0051] In one implementation, a method of transferring fluid to electronic components comprising dispensing a fluid into a cavity within a container, whereby the cavity has an upper opening that is defined by a generally horizontal rim. A blade is moved across the rim from a first position to a second position on the rim in a direction of motion. The blade has a wiping surface that is configured to make contact with a surface of the container and span the upper opening such that the moving of the blade displaces a volume of fluid from the cavity. Such displacement leads to the formation of a smooth fluid surface in the cavity at a height above the bottom of the cavity. A portion of an electronic component is dipped through the smooth fluid surface into the fluid within the container such that the fluid is transferred to a portion of the electronic component. The method can include the blade being angled with respect to the direction of motion such that the blade displaces a volume of excess fluid in a direction that is angled with respect to the direction of motion of the blade. In one implementation, the moving of the blade across the rim of the cavity displaces a volume of fluid from the cavity, such that a fluid surface is created at a consistent and repeatable height above the bottom of the cavity.

[0052] In one implementation the method further includes moving a second blade across the rim from a third position to a fourth position on the rim wherein the movement of the second blade across the rim is in a direction of motion that is opposite of the direction of motion of the first blade. The second blade has a wiping surface that is configured to make contact with a surface of the container and spans the upper opening, such that the moving of the blade causes the blade to displace a volume of fluid from the cavity such that a smooth fluid surface is created in the cavity at a consistent and repeatable height. In one implementation the movement of the first blade can cause the displacement of the volume of the fluid to a first location on the container away from the cavity and the movement of the second blade can cause the

displacement of the volume of fluid to a second location on the container away from the cavity, wherein the first and second positions are different. In another implementation, the second blade is moved over an area of the surface of the container that the wiping surface of the first blade does not make contact with. In another implementation, the smooth fluid surface is created at a height within the cavity that is in a range of 79% to 81% of a total height of the cavity. In another implementation, a range of 89.5% to 90.5% of a total volume of the cavity contains fluid.

[0053] In one implementation, the method further includes dispensing a fluid into a second cavity within a container, wherein the second cavity is separate from the first cavity and has an upper opening defined by a generally horizontal rim. A second blade having a wiping surface that is configured to make contact with a surface of the container and span the upper opening of the second cavity is moved across the rim of the second cavity from a first position on the rim of the second cavity to a second position on the rim of the second cavity. The movement of the second blade causes the displacement of a volume of fluid out of the second cavity, such that a smooth fluid surface is created in the second cavity at a height above a bottom of the second cavity. The method further includes dipping a second electronic component through the smooth fluid surface into the fluid that is contained within the second cavity such that the fluid is transferred to the portion of the second electronic component. In one implementation, the liquid that is contained within the first cavity is of a different type than the liquid that is contained within the second cavity such that the first blade displaces the liquid of a first type and the second blade displaces the liquid of a second type. In one implementation, the moving of the second blade across the rim of the second cavity causes a displacement of a volume of fluid from the second cavity such that a fluid surface is created in the second cavity at a consistent and repeatable height. In another implementation, the smooth fluid surface is created at a height within the second cavity that is in a range of 79% to 81% of a total height of the second cavity. In another implementation, a range of 89.5% to 90.5% of a total volume of the second cavity contains fluid. In another implementation, the first electronic component that is dipped into the first cavity is of a different type than the second electronic component that is dipped into the second cavity. In another implementation, the method can further include measuring the height of the electronic component using a component image device. Such height can be used to determine the position to which to move the electronic component holder such that the electronic component is dipped into the cavity in order to wet the portion of the electronic component with the fluid.

[0054] We claim as follows:

Claims

CLAIMS 1. A fluid transfer unit, comprising:

a container having a cavity, the cavity having an upper opening defined by a generally horizontal rim, the cavity containing a volume of fluid;

a blade having a wiping surface that is configured to make contact with a surface of the container and further configured to be movable over the rim spanning the opening of the cavity at a fixed point of one end of the rim; and

a blade driver engaging the blade being configured to move the blade from a first position to a second position on an opposite end of the rim, wherein such movement across the rim occurs in a direction of motion, such movement causing the blade to displace a volume of fluid out of the cavity, such that a smooth fluid surface is created in the cavity at a height above a bottom of the cavity, whereby the electronic component can be dipped into the fluid through the smooth fluid surface.

2. The apparatus of claim 1, wherein the cavity is of a size that is configured for the dipping of a component of a specific size.

3. The apparatus of claims 2 or 3, wherein the blade displaces a volume of fluid out of the cavity such that a fluid surface is created in the cavity at a consistent and repeatable height above the bottom of the cavity.

4. The apparatus of claims 1-3, wherein the blade is angled with respect to the direction of motion of the blade such that it displaces the volume of excess fluid in a direction that is angled with respect to the direction of motion of the blade.

5. The apparatus of claims 1-4, further comprising a second blade, a second blade having a wiping surface that is placeable against the rim to span the opening at a fixed point of one end of the rim, the second blade engaged by the blade driver for movement of the second blade from a third position to a fourth position on an opposite end of the rim, wherein such movement across the rim is the same as the movement of the first blade and in the opposite direction of motion of the first blade, such movement of the second blade causing the second blade to displace a volume of fluid.

6. The apparatus of claim 5, wherein the first blade is configured to displace a volume of the fluid to a first location on the container away from the cavity and the second blade is configured to displace a volume of the fluid to a second location on the container away from the cavity, such second location being different than the first location.

7. The apparatus of claims 5 or 6, wherein the first blade is mounted at a first site and the second blade is mounted at a second site, the first site of the first blade being off-set from the second site of the second blade along an axis that is perpendicular to the directions of motion of the first and second blades.

8. The apparatus of claims 1-7, wherein the smooth fluid surface is created at a certain predetermined target height level from a position at the bottom of the cavity within a deviation of a few percent.

9. The apparatus of claims 1-7, wherein a predetermined target percentage range of a total volume of the cavity within a deviation of a few percent of the total volume of the cavity contains fluid.

10. The apparatus of claims 1-9, further comprising:

the container having a second cavity, the second cavity being separate from the first cavity and having an upper opening defined by a generally horizontal rim, the cavity being filled with a volume of fluid;

a second blade having a wiping surface that is configured to make contact with the surface of the container and further configured to be movable over the rim spanning the opening of the second cavity at a fixed point of one end of the rim;

a second blade driver engaging the second blade being configured to move the blade from a first position on the rim of the second cavity to a second position on an opposite end of the rim of the second cavity, wherein such movement across the rim causes the second blade to displace a volume fluid out of the second cavity, such that a smooth fluid surface is created in the second cavity at a height above a bottom of the second cavity, whereby a second electronic component can be dipped into the fluid through the smooth fluid surface.

11. The apparatus of claim 10, wherein the second cavity is of a size that is configured for the dipping of the second component of a specific size.

12. The apparatus of claims 10 or 11, wherein the second blade displaces a volume of fluid out of the second cavity such that a fluid surface is created in the second cavity at a consistent and repeatable height above the bottom of the second cavity.

13. The apparatus of claims 10-12, wherein the first blade displaces a volume of fluid of a first type from the first cavity and the second blade displaces a volume of fluid of a second type from the second cavity, the fluid of the second type being different than the fluid of the first type.

14. The apparatus of claims 10-13, wherein the smooth fluid surface is created at a certain target height level from a position at the bottom of the second cavity within a deviation of a few percent.

15. The apparatus of claims 10-13, wherein a predetermined target percentage range of a total volume of the second cavity within a deviation of a few percent of the total volume of the second cavity contains fluid.

16. The apparatus of claims 1-15, further comprising a component holding member, such component holding member including at least two vacuum nozzles with which the two electronic components can be picked up simultaneously and dipped into the fluid within the cavity at the same time.

17. The apparatus of claims 1-15, further comprising a component image pickup device, the component image pickup device configured to measure the height of an electronic component within the component holding member, the height of the electronic component within the component holding member determining at what position to move the component holding member such that the electronic component is placed at a depth within the cavity whereby a portion of the electronic holding member is wetted.

18. A method of transferring fluid to electronic components comprising:

dispensing a fluid into a cavity within a container, the cavity having an upper opening defined by a generally horizontal rim;

moving a blade across the rim from a first position to a second position on the rim in a direction of motion, the blade having a wiping surface that is configured to make contact with a surface of the container and span the upper opening, the moving of the blade displacing a volume of fluid from the cavity, such that a smooth fluid surface is created in the cavity above a bottom of the cavity;

dipping a portion of an electronic component through the smooth fluid surface into the fluid that is contained within the cavity such that the fluid is transferred to the portion of the electronic component.

19. The method of claim 18, wherein the moving a blade across the rim displaces a volume of fluid from the cavity, such that a fluid surface is created in the cavity at a consistent and repeatable height above the bottom of the cavity.

20. The method of claims 18 or 19, wherein the blade is angled with respect to the direction of motion of the blade such that it displaces the volume of fluid in a direction that is angled with respect to the direction of motion of the blade.

21. The method of claims 18-20, further including moving a second blade across the rim from a third position to a fourth position on the rim the second blade having a wiping surface that is configured to make contact with a surface of the container and span the upper opening, wherein the moving of the second blade across the rim is in a direction of motion that is opposite of the direction of motion of the first blade, such movement of the second blade causing the second blade to displace a volume of fluid from the cavity, such that a smooth fluid surface is created in the cavity at a height above the bottom of the cavity.

22. The method of claim 21, wherein the moving of the second blade displaces a volume of fluid from the cavity, such that a fluid surface is created in the cavity at a consistent and reproducible height above the bottom of the cavity.

23. The method of claims 21 or 22, wherein the movement of the first blade causes the displacement of a volume of the fluid to a first location on the container away from the cavity and the movement of the second blade causes the displacement of a volume of the fluid to a second location on the container away from the cavity, such second location being different than the first location.

24. The method of claims 21-23, wherein moving the second blade, includes moving the second blade over an area of the surface of the container that the wiping surface of the first blade does not make contact with.

25. The method of claims 18-24, wherein the smooth fluid surface is created at a certain predetermined target height level from a position at the bottom of the cavity, within a deviation of a few percent.

26. The method of claims 18-24,wherein a predetermined target percentage range of a total volume of the second cavity within a deviation of a few percent of the total volume of the second cavity contains fluid.

27. The method of claims 18-26, further including:

dispensing a fluid into a second cavity within a container, the second cavity being separate from the first cavity and having an upper opening defined by a generally horizontal rim; moving a second blade across the rim of the second cavity from a first position on the rim of the second cavity to a second position on the rim of the second cavity in a direction of motion, the second blade having a wiping surface that is configured to make contact with a surface of the container and span the upper opening of the second cavity, the moving of the second blade displacing a volume of fluid from the second cavity, such that a smooth fluid surface is created in the second cavity at a height above a bottom of the second cavity;

dipping a portion of a second electronic component through the smooth fluid surface into the fluid that is contained within the second cavity such that the fluid is transferred to the portion of the second electronic component.

28. The method of claim 27, wherein the movement of the second blade across the rim of the second cavity causes the displacement of a volume of fluid from the second cavity, such that a fluid surface is created in the second cavity at a consistent and repeatable height above the bottom of the second cavity.

29. The method of claims 27 or 28, wherein the first blade is configured to displace a volume of fluid of a first type from the first cavity and the second blade is configured to displace a volume of fluid of a second type from the second cavity, the fluid of the second type being different than the fluid of the first type.

30. The method of claims 27-29, wherein the smooth fluid surface is created at a certain predetermined target height level from a position at the bottom of the cavity within a deviation of a few percent.

31. The method of claims 27-29, wherein a target percentage of a total volume of the second cavity, within a deviation of a few percent, contains fluid.

32. The method of claims 27-31, wherein the first electronic component is of a different type than the second electronic component.

33. The method of claims 18-32, further including the step of measuring the height of the electronic component using a component image pickup device, such height of the electronic component being used to determine the depth at which to dip the electronic component into the cavity to in order to wet the portion of the electronic component with the fluid.