GB2111863A - Spray apparatus and method of spraying articles and an article made by the method - Google Patents
Spray apparatus and method of spraying articles and an article made by the method Download PDFInfo
- Publication number
- GB2111863A GB2111863A GB08138934A GB8138934A GB2111863A GB 2111863 A GB2111863 A GB 2111863A GB 08138934 A GB08138934 A GB 08138934A GB 8138934 A GB8138934 A GB 8138934A GB 2111863 A GB2111863 A GB 2111863A
- Authority
- GB
- United Kingdom
- Prior art keywords
- air
- delivery system
- tubular member
- holes
- flux
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
- B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3489—Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
Abstract
Apparatus to spray liquid resin flux 4 from a trough 5 onto a PCB 2 has a rotatable perforated drum 3 containing an air delivery system 7 to deliver a flow of air substantially uniform along its length. The air delivery system has three tubular members, 7a, 7b, 7c. The first tubular member is arranged within the second and has a plurality of holes to allow air introduced into the first tubular member to communicate with the second. The second tubular member is arranged within the third tubular member to allow air in the second member to communicate with the third. Thus air can flow from the first member to the second and then to the third member and be expelled from the third member towards the flux on the carrier drum. <IMAGE>
Description
SPECIFICATION
Spray apparatus and method of spraying articles
and an article made by the method
This invention relates to spray apparatus particularly
but not exclusively for spraying liquid resin flux onto
printed circuit boards (hereinafter referred to as
PCB's), to a method of spraying, and to an article, for
example a PCB, made by the method.
It is known to automatically produce circuits
including PCB's by performing a series of operations
along a computer controlled conveyer system, with
limited hand assembly of some large circuit compo
nents. Such circuits may, for example, be used in
televisions. During the making of each circuit it is
necessary to apply flux onto the board prior to
soldering of individual circuit components thereon.
Several methods have been proposed for applying
the flux to the PCB's. One such method involves
creating a foam with minute air bubbles in liquid
resin flux and applying the foam to the underside of
the PCB prior to the soldering operation. However,
this method tends to have the disadvantage that too
much flux is applied and non-uniformly. The foam,
by capillary action, tends to force itself through
clearance holes in the PCB surrounding the leads of
the various circuit components, for example, and
may be particularly troublesome to adjustable circuit
components such as small potentiometers, whose
functioning may be impaired. The flux residue left on
the PCB after the soldering operation can cause
corrosion or current creepage problems.
Another proposed method involves a rotatable flux carrier arranged in a shallow trough of flux; the
carrier rotates and, as it does so picks up flux from
the trough and carries it adjacent the underside of
the PCB. The carrier is perforated and air is blown
through the perforations towards the PCB and on the way picks up the liquid resin flux which, due to its
viscous nature, extends across the perforations. The
effect is to spray the underside of the PCB with flux
as the PCB is moved over the carrier. However, a
disadvantage has been found with various appar ratus embodying this method that the PCB's are not
uniformly coated with flux because of the pressu
rized air delivery system.Techniques have been
developed for cleaning flux residue from the boards
after soldering but such techniques, of course, involve an extra operation, extra expense and add to
the production costs of the circuits and may not in
the end be entirely satisfactory.
It is an object of the present invention to alleviate
the aforementioned disadvantages.
According to the present invention there is pro
vided spray apparatus to spray, for example liquid
resin flux onto a PCB (as herein defined), comprising
a rotatable perforated flux carrier and an air delivery
system extending without the carrier, the air delivery system comprising a first tubular member, a second
tubular member and a third tubular member, the
first tubular member being arranged within the
second and having a plurality of holes to allow air
introduced into the first tubular member to com municate with the second, and the second tubular member being arranged within the third tubular member to allow air in the second member to communicate with the third, the carrier being capable on rotation of carring flux adjacent the air delivery system, the tubular members being such that air can flow from the first member to the second and then to the third member and be expelled from the third member towards the flux on the carrier in a manner which is substantially uniform along the length of the third member to thereby spray flux uniformly onto,for example, a PCB.
Further according to the present invention there is provided a method of spraying articles, comprising carrying a viscous liquid, for example, liquid resin flux, adjacent an air delivery system and moving an article, for example a PCB (as herein defined), relative to the air delivery system, blowing air through a first tubular member of the air delivery system and into a second tubular member of the system surrounding the first, and into a third tubular member surrounding the second tubular member of the system expelling air from the third tubular member in a substantially uniform manner along its length towards the viscous liquid, and thereby spraying the viscous liquid uniformly onto the article as the article is moved relative to the air delivery system.
Still further according to the present invention there is provided a PCB sprayed with flux by the method of the immediately preceding paragraph, and also a circuit including such a PCB on which a subsequent soldering operation has been performed.
Preferably, the first, second and third tubular members are of co-axial cylindrical form and offset from the carrier axis. The carrier is, preferably, a drum of steel mesh. Preferably, the inner one of the three tubular members has an external diameter less than, and spaced from, the internal diameter of the middle one of the three members, the inner one of the members is provided with holes communicating with the middle one of the members, and the middle one of the members is provided with holes communicating with the outer one of the members. The holes on the inner member are, preferably, located one at each end of said member and so that when air is fed into said member it is expelled therefrom into the annular chamber defined between the inner and middle tubular members before being expelled from more holes in the middle member, which may be in the form of slots.The slots in the middle member may extend parallel to the axis of the inner member, and the holes in the inner member may be circular. If air is to be fed into the air delivery system from one end of the inner member the circular hole nearer that end may be smaller than the hole at the other end to equalize air pressure distribution in the first tubular member.
The slots may be identical and diametrically opposite to the holes in the inner member and may also be co-linear and offset along the axis of the inner member from said holes. The third tubular member is, preferably, provided with a single row of holes extending parallel to the carrier axis and arranged in the same diametrical plane as the holes, but nearer to the holes in the inner member than to those in the middle member.
Preferably, the air supply to the air delivery system is controlled automatically in response to the position of the article being sprayed. Where the article is a PCB a sensor such as a capacitive sensor may be arranged to detect the presence or absence of the
PCB relative to the air delivery system and switch the air supply on or off accordingly. The pressure of the air supply may be adjustable.
An embodiment of spray apparatus in accordance with the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:
Figure 1 shows a much simplified sectional side view of the spray apparatus positioned below a PCB;
Figure 2 shows a much simplified sectional end view of the apparatus, and
Figures 3a, 3b and 3c show the component parts of an air delivery system of the apparatus and is to a reduced scale.
Figures 1 and 2 show spray apparatus generally designated 1 for spraying liquid resin flux onto the underside of a PCB 2.
The apparatus 1 has a carrier 3 mounted for rotation by motor M about axis X -X. The carrier 3 is a hollow, cylindrical, perforated drum made from a steel mesh, and as shown the mesh extends in liquid resin flux 4 in trough 5. Flux may be introduced continually into the trough 5 through pipe 6 to
maintain the flux at the same level in the trough while the carrier 3 is rotated.
An air delivery system 7 consists of first, second and third co-axial, cylindrical, metal tubular mem
bers 7a, 7b, 7c which extend in the upper region of the carrier and are mounted parallel to axis X -X.
The first tubular member 7a has a plurality of
holes 8a represented by gaps through which air may
be passed from the first member to the second
member 7b. The second member 7b is also provided with holes 8b which allow air to pass into the annular space between members 7a and 7b. The holes 8b are
rectangular slots and the holes 8a are circular and of
slightly differing diameters. The circular holes 8a,
provided in the first tubular member 7a are shown
more clearly in Figure 3a and the slots 8b provided in the second (middle) tubular member 7b are shown
in Figure 3b. The slots are positioned diametrically
opposite the circular holes 8a. The inner member 7a
is slid inside the middle member 7b to form an
annular chamber therebetween. The left-hand circu
lar hole 8a is slightly smaller than the right-hand
circular hole for reasons explained below.Each slot
8b extends axially towards the centre of the carrier 3 from a position opposite the centre of each respective circular hole 8a. The third (i.e. outer) tubular
member 7c has a row of circular holes 9 extending in
the same plane as the circular holes and slots 8a, 8b
but which are of a lesser diameter than said circular
holes (see Figures 3). The component parts of the
delivery system 7 are assembled with the slots
remote from circular holes 8a and 9.
In operation the PCB shown at 2 in Figure 1 is
advanced from left to right by a conveyer system
(not shown) as the carrier 3 is slowly rotated, perhaps at a speed of 20 to 25 r.p.m. As the carrier 3 is rotated it picks up liquid resin flux 4 from trough 5, while the level of flux in the trough is maintained substantially constant. The flux picked up by the steel mesh at the bottom of carrier 3 is carried, on rotation of the carrier, adjacent the underside of the
PCB. Pressurised air is fed into inner member 7a from the left of Figure 1 then out from the delivery system 7 as a fine jet air spray through the holes 9.
The air, which is expelled uniformly along the length of member 7c hits the carrier and sprays flux present thereon (which extends across the perforations of the mesh due to it viscosity) uniformly over the underside of the PCB 2. Since the air is introduced into the air delivery system 7 from one end, the circular hole 8a nearest that end is made slightly smaller than the upper circular hole 8 at the other end to equalise air pressure distribution. Once the underside has been sprayed with flux the PCB is conveyed to another operating station where electrical components 10 are soldered onto the PCB 2.
In order to synchronise the spraying operation, one or more sensors (not shown) may be employed to sense the presence of the PCB in its correct location for flux spraying to begin, and to indicate when flux spraying should stop. Conveniently, a capacitive sensor may be used which is connected to automatically switch on or off the air to the air delivery system 7. Also, the pressure of the air supply may be adjustable; in general the pressure may be about 40 p.s.i. The width of a PCB is typically about 30 cm and suitable dimensions for the various parts of the delivery system are as follows: first tubular member 7a - 362 mm length - holes 9 of 0.5 mm and about 114 in number - outside diameter 25 mm. Other suitable dimensions may be ascertained directly from Figure 3 since this is to scale.
The wire mesh cylinder 3 is positioned within a tie-rod construction not shown and so adjusted as to ensure that the cylinder rotates concentrically about its axis X-X, thereby maintaining a constant gap between cylinder 3 and the air delivery system 7.
Additionally, during non-flux spraying periods a low pressure air supply is maintained to the delivery system 7 in order to assist in keeping holes 9 in an unrestricted condition.
CLAIMS (Filed on 29 Nov 1982)
1. Spray apparatus to spray a liquid onto an article, said apparatus comprising a rotatable perforated liquid carrier and an air delivery system extending within the carrier, the air delivery system comprising a first tubular member, a second tubular member and a third tubular member, the first tubular member being arranged within the second and having a plurality of holes to allow air introduced into the first tubular member to communicate with the second, and the second tubular member being arranged within the third tubular member to allow air in the second member to communicate with the third, the carrier being capable on rotation of carrying liquid adjacent the air delivery system, the tubular members being such that air can flow from the first member to the second and then to the
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (16)
1. Spray apparatus to spray a liquid onto an article, said apparatus comprising a rotatable perforated liquid carrier and an air delivery system extending within the carrier, the air delivery system comprising a first tubular member, a second tubular member and a third tubular member, the first tubular member being arranged within the second and having a plurality of holes to allow air introduced into the first tubular member to communicate with the second, and the second tubular member being arranged within the third tubular member to allow air in the second member to communicate with the third, the carrier being capable on rotation of carrying liquid adjacent the air delivery system, the tubular members being such that air can flow from the first member to the second and then to the
third member and be expelled from the third mem
ber towards the liquid on the carrier in a manner
which is substantially uniform along the length of
the third member to thereby spray liquid uniformly
onto an article.
2. Apparatus according to Claim 1, wherein the
first, second and third tubular members are of
co-axial cylindrical form and offset from the carrier
axis.
3. Apparatus according to Claim 1 or Claim 2,
wherein the inner one of the members is provided
with holes communicating with the middle one of
the members, and the middle one of the members is
provided with holes communicating with the outer
one of the members.
4. Apparatus according to Claim 3 wherein the
holes on the inner member are located one at each
end of said member such that when air is fed into
said member it is expelled therefrom into the
annular chamber defined between the inner and
middle tubular members before being expelled from
holes in the middle member.
5. Apparatus according to Claim 3 or Claim 4,
wherein the holes in the middle member are slots
extending parallel to the axis of the inner member,
and the holes in the inner member are circular.
6. Apparatus according to Claim 4 or Claim 5
wherein one hole of the inner member is smaller
than the other hole.
7. Apparatus according to claim 5, wherein the
slots are identical and diametrically opposite to the
holes in the inner member and are co-linear and
offset along the axis of the inner member from said
holes.
8. Apparatus according to any one of the preced
ing claims wherein the third tubular member is
provided with a single row of holes extending
parallel to the carrier axis and arranged in the same
diametrical plane as the holes of the other members,
but nearer to the holes in the inner member than to
those in the middle member.
9. Apparatus according to any one of the preced
ing claims, having means to automatically control
the air supply to the air delivery system in response to the position of the article being sprayed.
10. Spray apparatus to spray a liquid onto an
article, said apparatus being substantially as
hereinbefore described with reference to and as
illustrated in the accompanying drawings.
11. Spray apparatus to spray liquid resin flux
onto a printed circuit board, said apparatus compris
ing a rotatable perforated flux carrier and an air
delivery system extending within the carrier, the air
delivery system comprising a first tubular member, a second tubular member and a third tubular member,
the first tubular member being arranged within the
second and having a plurality of holes to allow air
introduced into the first tubular member to com
municate with the second, and the second tubular
member being arranged within the third tubular
member to allow air in the second member to
communicate with the third, the carrier being cap
able on rotation of carrying flux adjacent the air
delivery system, the tubular members being such that air can flow from the first member to the second and then to the third member and be expelled from the third member towards the flux on the carrier in a manner which is substantially uniform along the length of the third member to thereby spray flux uniformly onto, a printed circuit board.
12. A method of spraying a liquid onto an article, comprising carrying a liquid adjacent an air delivery system and moving an article relative to the air delivery system, blowing air through a first tubular member of the air delivery system and into a second tubular member of the system surrounding the first, and into a third tubular member surrounding the second tubular member of the system thereby expelling air from the third tubular member in a substantially uniform manner along its length towards the liquid, and thereby spraying the liquid uniformly onto the article as the article is moved relative to the air delivery system.
13. A method according to Claim 12, wherein air is fed onto the air delivery system from one end of the inner member.
14. A method of spraying a liquid onto an article using spray apparatus according to any one of
Claims 1 to 11.
15. A method of spraying articles, comprising carrying liquid resin flux adjacent an air delivery system and moving a printed circuit board relative to the air delivery system, blowing air through a first tubular member of the air delivery system and into a second tubular member of the system surrounding the first, and into a third tubular member surrounding the second tubular member of the system expelling air from the third tubular member in a substantially uniform manner along its length towards the flux, and thereby spraying the flux uniformly onto the printed circuit board as it is moved relative to the air delivery system.
16. An article sprayed with a liquid by an apparatus according to any one of Claims 1 to 11 or by a method according to any one of claims 12 to 15.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08138934A GB2111863B (en) | 1981-12-24 | 1981-12-24 | Spray apparatus and method of spraying articles and an article made by the method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08138934A GB2111863B (en) | 1981-12-24 | 1981-12-24 | Spray apparatus and method of spraying articles and an article made by the method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2111863A true GB2111863A (en) | 1983-07-13 |
| GB2111863B GB2111863B (en) | 1985-09-04 |
Family
ID=10526846
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08138934A Expired GB2111863B (en) | 1981-12-24 | 1981-12-24 | Spray apparatus and method of spraying articles and an article made by the method |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2111863B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0336659A2 (en) * | 1988-04-06 | 1989-10-11 | AT&T Corp. | Method and apparatus for applying flux to a substrate |
| EP0359324A1 (en) * | 1988-09-15 | 1990-03-21 | Koninklijke Philips Electronics N.V. | Device for providing a flux layer on a printed board |
| EP0789391A3 (en) * | 1996-02-08 | 1998-01-07 | Zevatech, Incorporated | Method and apparatus for application of flux, paste, or adhesive to bump array interconnections |
| US6031242A (en) * | 1998-01-23 | 2000-02-29 | Zevatech, Inc. | Semiconductor die in-flight registration and orientation method and apparatus |
| US6129040A (en) * | 1997-09-05 | 2000-10-10 | Esec Sa | Semi-conductor mounting apparatus for applying adhesive to a substrate |
| US6135339A (en) * | 1998-01-26 | 2000-10-24 | Esec Sa | Ultrasonic transducer with a flange for mounting on an ultrasonic welding device, in particular on a wire bonder |
| US6157870A (en) * | 1997-02-18 | 2000-12-05 | Zevatech Trading Ag | Apparatus supplying components to a placement machine with splice sensor |
| US6179938B1 (en) | 1997-10-30 | 2001-01-30 | Esec Sa | Method and apparatus for aligning the bonding head of a bonder, in particular a die bonder |
| US6185815B1 (en) | 1997-12-07 | 2001-02-13 | Esec Sa | Semiconductor mounting apparatus with a chip gripper travelling back and forth |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6077022A (en) | 1997-02-18 | 2000-06-20 | Zevatech Trading Ag | Placement machine and a method to control a placement machine |
-
1981
- 1981-12-24 GB GB08138934A patent/GB2111863B/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0336659A2 (en) * | 1988-04-06 | 1989-10-11 | AT&T Corp. | Method and apparatus for applying flux to a substrate |
| EP0336659A3 (en) * | 1988-04-06 | 1990-11-28 | American Telephone And Telegraph Company | Method and apparatus for applying flux to a substrate |
| EP0359324A1 (en) * | 1988-09-15 | 1990-03-21 | Koninklijke Philips Electronics N.V. | Device for providing a flux layer on a printed board |
| US5005766A (en) * | 1988-09-15 | 1991-04-09 | U.S. Philips Corporation | Device for providing a flux layer on a printed board |
| EP0789391A3 (en) * | 1996-02-08 | 1998-01-07 | Zevatech, Incorporated | Method and apparatus for application of flux, paste, or adhesive to bump array interconnections |
| US6157870A (en) * | 1997-02-18 | 2000-12-05 | Zevatech Trading Ag | Apparatus supplying components to a placement machine with splice sensor |
| US6129040A (en) * | 1997-09-05 | 2000-10-10 | Esec Sa | Semi-conductor mounting apparatus for applying adhesive to a substrate |
| US6179938B1 (en) | 1997-10-30 | 2001-01-30 | Esec Sa | Method and apparatus for aligning the bonding head of a bonder, in particular a die bonder |
| US6185815B1 (en) | 1997-12-07 | 2001-02-13 | Esec Sa | Semiconductor mounting apparatus with a chip gripper travelling back and forth |
| US6031242A (en) * | 1998-01-23 | 2000-02-29 | Zevatech, Inc. | Semiconductor die in-flight registration and orientation method and apparatus |
| US6135339A (en) * | 1998-01-26 | 2000-10-24 | Esec Sa | Ultrasonic transducer with a flange for mounting on an ultrasonic welding device, in particular on a wire bonder |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2111863B (en) | 1985-09-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19951224 |