GB1583192A - Processing of printed circuit boards - Google Patents
Processing of printed circuit boards Download PDFInfo
- Publication number
- GB1583192A GB1583192A GB1738577A GB1738577A GB1583192A GB 1583192 A GB1583192 A GB 1583192A GB 1738577 A GB1738577 A GB 1738577A GB 1738577 A GB1738577 A GB 1738577A GB 1583192 A GB1583192 A GB 1583192A
- Authority
- GB
- United Kingdom
- Prior art keywords
- printed circuit
- circuit board
- laser beam
- layer
- overcoating layer
- 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.)
- Expired
Links
Classifications
-
- 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
- H05K3/0011—Working of insulating substrates or insulating layers
- H05K3/0017—Etching of the substrate by chemical or physical means
- H05K3/0026—Etching of the substrate by chemical or physical means by laser ablation
- H05K3/0032—Etching of the substrate by chemical or physical means by laser ablation of organic insulating material
- H05K3/0035—Etching of the substrate by chemical or physical means by laser ablation of organic insulating material of blind holes, i.e. having a metal layer at the bottom
-
- 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
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0393—Flexible materials
-
- 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
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/01—Tools for processing; Objects used during processing
- H05K2203/0147—Carriers and holders
- H05K2203/0165—Holder for holding a Printed Circuit Board [PCB] during processing, e.g. during screen printing
-
- 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
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/05—Patterning and lithography; Masks; Details of resist
- H05K2203/0548—Masks
- H05K2203/0554—Metal used as mask for etching vias, e.g. by laser ablation
-
- 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
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/08—Treatments involving gases
- H05K2203/082—Suction, e.g. for holding solder balls or components
-
- 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
- H05K3/0008—Apparatus or processes for manufacturing printed circuits for aligning or positioning of tools relative to the circuit board
-
- 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
- H05K3/22—Secondary treatment of printed circuits
- H05K3/28—Applying non-metallic protective coatings
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Laser Beam Processing (AREA)
Description
(54) IMPROVEMENTS IN OR RELATING TO THE PROCESSING
OF PRINTED CIRCUIT BOARDS
(71) We, UNITED KINGDOM ATO
MIC ENERGY AUTHORITY, London, a
British Authority, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The present invention relates to printed circuit boards, and more specifically to flexible printed circuit boards.
Flexible printed circuit boards are manu factured by a process which includes the operations of coating one side of a sheet of copper foil with a flexible insulating layer, photo-etching the copper foil to provide the conductors of the electrical circuit, and applying a second, overcoating, flexible insulating layer to the exposed copper strips forming the conductors. The overcoating insulating layer has holes in it at positions which correspond to those at which it is desired to make soldered connections between the conductors and separate components which go to make up the electrical circuit. Finally, the lead-through holes are drilled at every connecting point, and the completed printed circuit is punched out on a profile cutting press.
One of the problems associated with the manufacture of flexible printed circuit boards by the above process is that of ensuring that the pre-formed holes in the overcoating layer are in correct register with the copper conductors of the electrical circuit.
A problem also arises if at a later date it is desired to remove part of the overcoating layer, for example, to rectify a break in the continuity of one of the conductors. The same problem arises in connection with rigid printed circuit boards if they have been covered with a conformal overcoating protective layer after assembly. At present such overcoating layers are removed by hand using small abrasive or cutting tools, which is slow, laborious, and can lead to damage to the the portion of the electrical circuit it is desired to expose. Alternatively, solvent techniques can be used, but it is difficult to restrict the application of the solvents to the required regions only.
According to the present invention there is provided a method of manufacturing a printed circuit board of the type which has an overcoating layer, including the operation of subjecting a region of the overcoating layer it is desired to remove to the action of a laser beam of power sufficient to vapourise the overcoating layer wherein regions of the printed circuit board which it is desired should not be removed are protected by means of a reflecting mask and the laser beam is scanned over the surface of the printed circuit board to effect removal of the overcoating layer where desired.
The printed circuit board may be a flexible printed circuit board, and the overcoating layer may be a layer of insulating material covering the metal conductors of the electrical circuit formed on the printed circuit board.
Alternatively the printed circuit board may be a conventional rigid printed circuit board and the overcoating layer may be a protective layer applied to the printed circuit board after the electrical circuit has been assembled.
According to the invention in a particular aspect, there is provided a method of manufacturing a flexible printed circuit board including the operations of photoetching a conducting lamina having a flexible insulating layer attached to one side to provide the conductors of an electrical circuit, depositing a second insulating layer on the exposed side of the conductors so formed, depositing a reflecting coating on selected regions of the second insulating layer, scanning a laser beam of power sufficient to vapourise the second insulating layer so as to expose those regions of the conductors which correspond to the regions of the second insulating layer which are not covered by the reflecting coating, and removing the reflecting coating.
The reflecting coating may be in the form of a metal lamina with appropriate holes formed in it. The holes in the lamina may be formed by photo-etching techniques such as are well-known in the semiconductor device art, or it may consist of regions of metal deposited on the second insulating layer.
A suitable laser for use in performing the invention is a gas laser of the type which uses a gaseous mixture containing carbon dioxide gas as the lasing medium.
The invention will now be described, by way of example, with reference to the drawings accompanying the Provisional
Specification in whizz Figure la and 1b show plan and elevational views of a flexible printed circuit board in a condition ready for a laser machining operation according to the invention to be carried out;
Figure 2 shows diagrammatically an apparatus for carrying out the laser machining operation previously referred to,
Figure 3 shows diagrammatically another arrangement for carrying out the laser machining operation,
Figure 4 shows diagrammatically another arrangement for carrying out the laser machining operation,
Figure 5 shows diagramatically a fourth arrangement for carrying out the laser machining operation and
Figure 6 shows diagrammatically an
arrangement for subjecting a defined area of
a flexible printed circuit board to a laser
machining operation.
Referring to Figures 1(a) and 1(b), a method of manufacturing a flexible printed circuit board includes the operations of depositing a layer of copper upon a base flexible insulating layer 2 made of polyester photo-etching the copper layer by means of techniques which are well-known in the art of manufacturing electronic devices to provide a system of conductors 3, and over layer the system of conductors 3 with a second flexible insulating layer 4. A second, reflecting, copper layer 5 is then deposited on the layer 4 and photo-etched using the same techniques as before, to provide holes 6 which coincide with those regions of the conductors 3 which it is desired to expose to enable separate components of the electrical circuit to be soldered to the conductors 3 to form the desired electrical circuit. Other holes 7 are formed in the layer 5 to delineate the final flexible printed circuit. The assembly is then subjccted to a laser machining operation in which a focussed laser beam is scanned over the surface of the layer 5. The laser beam vapourises the layer 4 where it is exposed by the holes 6 and 7 in the layer 5, thus clearing the desired regions of the strips 3 and cutting out the printed circuit. The copper layer 5 is then removed before the separate components are soldered into place. The copper layer 5 can be removed by any convenient process.
A carbon dioxide gas laser having a power output of about 400 watts is suitable for carrying out the process.
The scanning of the laser beam over the layer 5 on the printed circuit board 1 can be carried out on an apparatus such as that shown in figure 2. The printed circuit board 1 is mounted on a drum 21 with the layer 5 exposed. The drum 21 is so mounted on a drum 21 with the layer 5 exposed. The drum 21 is so mounted that it can be moved in an axial direction as well as be rotated. A beam 22 from a carbon dioxide laser source having a power output of about 400 watts, which is not shown, is brought to a focus on the layer 5 of the printed circuit board 1 by means of a lens 23. Vapour arising from the printed circuit board 1 is removed by an extraction system 24. The diameter of the focal spot 25 of the laser beam 22 is arranged to be approximaely 0.030", and the drum 21 is arranged to rotate at a speed such that the focal spot 25 scans the surface of the layer 5 at a speed of some 1.7 metres/sec. The translational speed of the drum 21 is such that there is a 50% overlap of each traverse of the focal spot 25 over the surface of the layer 5 on the printed circuit board 1.
Figure 3 shows another arrangement for scanning the laser beam over the layer 5 on the printed circuit board 1. The printed circuit board 1 is laid on a table 31 which can be moved in the direction shown. An optical head 32 is mounted so that it can be oscillated in directions perpendicular to that in which the table 31 is moved. The optical head 32 includes a flat mirror 33 arranged to deflect a laser beam 34 through an angle of 45 degrees and a lens 35 arranged to brig the laser beam 34 to a focal spot 36 of some 0.030" diameter on the surface of the layer 5, as before. As before, the printed circuit board 1 is moved by half the diameter of the focal spot 36 of the beam 34 between each scan of the focal spot 36 across the layer 5 of the printed circuit board 1.
Figure 4 shows another way in which the laser beam can be scanned over the surface of the layer 5 on the printed circuit board 1.
The printed circuit board 1 is mounted on a conveyor 41 with the layer 5 uppermost. A beam 42 of light from a 400 watt carbon laser which is not shown, is directed at a rotating polygonal mirror 43. Light is reflected from the rotating mirror 43 onto a plane mirror 44 and thence to a spherical focussing mirror 45 which brings the laser beam 42 to a focus on the surface of the layer 5 on the printed circuit board 1. The rotation of the mirror 43 causes the laser beam 42 to be scanned repeatedly across the surface of the layer 5 on the printed circuit board 1. The angular relationship between the axis of rotation of the rotating mirror 43 and the direction of motion of the conveyor 41 is so adjusted that the focus of the laser beam is scanned across the conveyor 41 carrying the printed circuit board 1 in a direction which has a component of velocity in the direction of motion of the conveyor 41 equal to the speed of the conveyor 41 so that the focus of the laser beam 42 is scanned across the printed circuit board 1 at right angles to the direction of motion of the printed circuit board 1. The rate of scan in relation to the rate of advance of the printed circuit board is arranged to be such that there is an overlap of half the width of the focal spot at each scan of the laser beam 42 across the printed circuit board 1.
Figure 5 shows an arrangement in which a laser beam 51 from a 250 watt carbon dioxide laser is caused to scan over a printed circuit board 1 by means of two mirrors, 52 and 53, respectively, which are oscillated about two perpendicular axes 54 and 55 which lie in the planes of the mirrors 52 and 53. The laser beam 51 and the mirrors 52 and 53 are so arranged that the laser beam 51 is incident on the mirrors 52 and 53 at positions which lie on the axes 54 and 55 about which the mirrors 52 and 53 are oscillated. A lens 56 is arranged to bring the laser beam 51 to a focus on the printed circuit board 1 in a spot 0.030" in diameter.
The mirror 52 is oscillated at a speed which causes the focussed spot of the laser beam 51 to travel over the printed circuit board 1 in the 'x' direction, as indicated, with a velocity of about 1 or 2 metres/sec.
The mirror 53 is oscillated at a speed which causes the focused spot of the laser beam 51 to travel over the printed circuit board 1 in the 'y' direction, as indicated, with a suitable velocity to produce a 50% beam overlap.
Figure 6 shows an apparatus which is particularly useful for removing the conformal layer of a conventional printed circuit.
In the apparatus illustrated in Figure 6 a scanning arrangement such as that described with reference to Figure 5 is contained in a scanning head 61. The scanning head 61 has a masking nozzle 62 which accurately defines the area scanned by the beam 63 from the gas laser 64. A vapour extract nozzle 65 is used to withdraw fumes arising from the vapourisation of the conformal coating 66 of the printed circuit 67.
WHAT WE CLAIM IS:
1. A method of manufacturing a printed circuit board of the type which has an overcoating layer, including the operation of subjecting a region of the overcoating layer it is desired to remove to the action of a laser beam of power sufficient to vapourise the overcoating layer wherein regions of the printed circuit board which it is desired should not be removed are protected by means of a reflecting mask and the laser beam is scanned over the surface of the printed circuit board to effect removal of the overcoating layer where desired.
2. A process according to claim 1 wherein the mask is formed by the operation of depositing a layer of metal on the surface of the overcoating layer, and etching away the metal layer to expose the overcoating layer, and etching away the metal layer to expose the overcoating layer at those regions of the printed circuit board at which it is desired to remove the overcoating layer.
3. A method according to claim 1 wherein the mask is formed by depositing a metal layer on the overcoating layer at those regions which it is desired to protect from the action of the laser beam.
4. A method according to any preceding claim wherein the printed circuit board comprises metal conductors deposited upon a flexible insulating substrate and covered with the overcoating layer.
5. A method of manufacturing a flexible printed circuit board including the operations of photo-etching a conducting lamina having a flexible insulating layer attached to one side to provide the conductors of an electrical circuit, depositing a second insulating layer on the exposed side of the conductors so formed, depositing a reflecting coating on selected regions of the second insulating layer, scanning a laser beam of power sufficient to vapourise the second insulating layer so as to expose those regions of the conductors which correspond to the regions of the second insulating layer which are not covered by the reflecting coating, and removing the reflecting coating.
6. A method according to any preceding claim wherein the laser beam is generated by a laser which includes carbon dioxide gas in the lasing medium.
7. A method according to any of claims 1 to 6 where the reflecting mask is made of copper.
8. An apparatus for carrying out a method of manufacturing a printed circuit board according to any preceding claim, comprising means for holding a printed circuit board, means for bringing the laser beam to a focus at the overcoating layer at a region of which it is desired to remove, and means for effecting relative movement between the laser beam and the printed circuit board to enable selected regions of the overcoating layer to be removed.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (11)
1. A method of manufacturing a printed circuit board of the type which has an overcoating layer, including the operation of subjecting a region of the overcoating layer it is desired to remove to the action of a laser beam of power sufficient to vapourise the overcoating layer wherein regions of the printed circuit board which it is desired should not be removed are protected by means of a reflecting mask and the laser beam is scanned over the surface of the printed circuit board to effect removal of the overcoating layer where desired.
2. A process according to claim 1 wherein the mask is formed by the operation of depositing a layer of metal on the surface of the overcoating layer, and etching away the metal layer to expose the overcoating layer, and etching away the metal layer to expose the overcoating layer at those regions of the printed circuit board at which it is desired to remove the overcoating layer.
3. A method according to claim 1 wherein the mask is formed by depositing a metal layer on the overcoating layer at those regions which it is desired to protect from the action of the laser beam.
4. A method according to any preceding claim wherein the printed circuit board comprises metal conductors deposited upon a flexible insulating substrate and covered with the overcoating layer.
5. A method of manufacturing a flexible printed circuit board including the operations of photo-etching a conducting lamina having a flexible insulating layer attached to one side to provide the conductors of an electrical circuit, depositing a second insulating layer on the exposed side of the conductors so formed, depositing a reflecting coating on selected regions of the second insulating layer, scanning a laser beam of power sufficient to vapourise the second insulating layer so as to expose those regions of the conductors which correspond to the regions of the second insulating layer which are not covered by the reflecting coating, and removing the reflecting coating.
6. A method according to any preceding claim wherein the laser beam is generated by a laser which includes carbon dioxide gas in the lasing medium.
7. A method according to any of claims 1 to 6 where the reflecting mask is made of copper.
8. An apparatus for carrying out a method of manufacturing a printed circuit board according to any preceding claim, comprising means for holding a printed circuit board, means for bringing the laser beam to a focus at the overcoating layer at a region of which it is desired to remove, and means for effecting relative movement between the laser beam and the printed circuit board to enable selected regions of the overcoating layer to be removed.
9. Apparatus according to claim 8 for
use in conjunction with a reflecting mask to delineate regions of the overcoating layer is desired to remove wherein the means for effecting relative movement between the printed circuit board and the laser beam is arranged to cause the laser beam to scan over the surface of the printed circuit board.
10. A method substantially as hereinbefore described with reference to the drawings accompanying the provisional specification.
11. An apparatus for carrying out a method of manufacturing a printed circuit board of the type which has an overcoating layer substantially as hereinbefore described with reference to Figure 2, or Figure 3, or
Figure 4 or Figure 5 or Figure 6 of the drawings accompanying the provisional specification.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1738577A GB1583192A (en) | 1978-04-26 | 1978-04-26 | Processing of printed circuit boards |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1738577A GB1583192A (en) | 1978-04-26 | 1978-04-26 | Processing of printed circuit boards |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1583192A true GB1583192A (en) | 1981-01-21 |
Family
ID=10094273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1738577A Expired GB1583192A (en) | 1978-04-26 | 1978-04-26 | Processing of printed circuit boards |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1583192A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2481564A1 (en) * | 1980-04-25 | 1981-10-30 | Voikhansky Moisei | FABRICATION LINE FOR WIRING PLATES OR PRINTED CIRCUIT |
| EP0062300A2 (en) * | 1981-04-06 | 1982-10-13 | FRITZ WITTIG Herstellung gedruckter Schaltungen | Process for making a circuit board |
| US4516010A (en) * | 1981-11-04 | 1985-05-07 | Licentia Patent-Verwaltungs-Gmbh | Method of manufacturing a radiation receiver |
| US4527041A (en) * | 1983-06-02 | 1985-07-02 | Kazuo Kai | Method of forming a wiring pattern on a wiring board |
| EP0388009A1 (en) * | 1989-02-14 | 1990-09-19 | General Electric Company | Method for forming via holes in polymer materials |
| DE4191065T (en) * | 1990-05-24 | 1992-06-25 | ||
| US5378137A (en) * | 1993-05-10 | 1995-01-03 | Hewlett-Packard Company | Mask design for forming tapered inkjet nozzles |
| US7947207B2 (en) | 2005-04-12 | 2011-05-24 | Abbott Cardiovascular Systems Inc. | Method for retaining a vascular stent on a catheter |
| CN118900506A (en) * | 2024-08-06 | 2024-11-05 | 北京蓝牧激光科技有限公司 | A laser-assisted thick copper microwave plate processing method |
-
1978
- 1978-04-26 GB GB1738577A patent/GB1583192A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2481564A1 (en) * | 1980-04-25 | 1981-10-30 | Voikhansky Moisei | FABRICATION LINE FOR WIRING PLATES OR PRINTED CIRCUIT |
| EP0062300A2 (en) * | 1981-04-06 | 1982-10-13 | FRITZ WITTIG Herstellung gedruckter Schaltungen | Process for making a circuit board |
| EP0062300A3 (en) * | 1981-04-06 | 1984-04-11 | FRITZ WITTIG Herstellung gedruckter Schaltungen | Process for making a circuit board |
| US4516010A (en) * | 1981-11-04 | 1985-05-07 | Licentia Patent-Verwaltungs-Gmbh | Method of manufacturing a radiation receiver |
| US4527041A (en) * | 1983-06-02 | 1985-07-02 | Kazuo Kai | Method of forming a wiring pattern on a wiring board |
| EP0388009A1 (en) * | 1989-02-14 | 1990-09-19 | General Electric Company | Method for forming via holes in polymer materials |
| DE4191065T (en) * | 1990-05-24 | 1992-06-25 | ||
| US5378137A (en) * | 1993-05-10 | 1995-01-03 | Hewlett-Packard Company | Mask design for forming tapered inkjet nozzles |
| US5417897A (en) * | 1993-05-10 | 1995-05-23 | Hewlett-Packard Company | Method for forming tapered inkjet nozzles |
| US7947207B2 (en) | 2005-04-12 | 2011-05-24 | Abbott Cardiovascular Systems Inc. | Method for retaining a vascular stent on a catheter |
| US8221112B2 (en) | 2005-04-12 | 2012-07-17 | Abbott Cardiovascular Systems, Inc. | Method for retaining a vascular stent on a catheter |
| CN118900506A (en) * | 2024-08-06 | 2024-11-05 | 北京蓝牧激光科技有限公司 | A laser-assisted thick copper microwave plate processing method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |