DE10027732A1 - Multiple use circuit board provided on both sides with rupture lines using displacement of circuit board relative to opposing laser beam elements - Google Patents

Abstract

The circuit board (10) is provided on both sides with rupture lines (9) provided as V-shaped grooves, formed via laser beams provided via a pair of aligned laser beam elements, positioned on the opposite sides of the relatively displaced circuit board. An Independent claim for an installation for manufacture of a multiple use circuit board is also included.

Description

The present invention relates to printed circuit boards with the finest scratches on both sides. and / or dividing lines and a method for producing the same double-sided laser beam.

Different methods are used for the separation of multiple-use printed circuit boards used, according to the increasingly fine structures and the high space costs and further the increasingly higher integration density with Equipping the printed circuit boards to the contours of the individual uses is always higher Requirements are made.

Usually, mechanical scribing on both sides (V-grooving, Scoring) using special milling cut lines in the x and y directions. Broken scratches are also often useful and necessary. Without  scoring on both sides cannot generally produce a high quality fracture or Contour edge of the individual benefits can be achieved and with perforation-like perforated and slot combinations can also not be high quality Contour edges can be reached or when breaking in Single-use delamination phenomena function from close to the scratch lines influence and / or destroy horizontal conductor structures. Can too unwanted breaks and already when loading the multiple benefits Delaminations occur in the area of the scratch lines.

In the circuit board industry, there is generally a distinction between one-sided, distinguish between double-sided, multilayer and flexible circuit boards. With all of these Wiring boards are usually made of so-called multiple panels or used. Production benefits of typically understood 510 × 610 mm or 510 × 510 mm and the like formats that in the usual printed circuit board manufacturing process-optimal and process-optimal Usage formats are and will be according to the individual circuit board for for example a cell phone, a VCR, a PCMCIA element and the like chosen in multiple arrangements. Such bare Multi-use printed circuit boards must then be divided into smaller multi-use Printed circuit boards are divided on common component placement machines are usable. Due to the ever increasing integration density of electronic components, especially the so-called surface-mounted Components (SMD: Surface mounted Devices; SMT: Surface mounted Technology) and BGA: ball-grid array and flip-chip assemblies up to COB: chip-on-board Technologies, an attempt is made to actively use as much space as possible. For this The reason is that the dividing lines of the individual printed circuit board benefits are as possible closely arranged to each other.

In addition to these requirements, the high packing density is becoming ever stronger Requirements for the wiring elements and often cannot Rectangular circuit boards meet these goals, but there must be any Geometric contours can be produced.  

Mechanical processing is usually carried out in the consumer electronics area with mostly one-sided and / or two-sided and / or plated-through holes double-sided circuit boards by means of punching tools and / or by means of drilling and Milling machines and / or by means of so-called scoring machines. With flexible Printed circuit boards are used similar processes and for multilayer printed circuit boards punching tools are generally not used, but predominantly Drilling and milling machines.

Drilling and milling machines, but also laser centers based on CO ₂ - and Nd: YAG-based lasers and excimer lasers are based on one-sided machining, while conventional scribing machines use corresponding scribing tools on both sides.

From US 4,856,400 (Robert A. Kelzer, Filed: 2/17/88; "Scoring Cutter") already special scoring tools or a device for both sides Scoring or milling of scratch lines in printed circuit boards described by the in particular a uniform scratch depth and thus a uniform distance between the both scoring lines are reached from each other, what a clean break or separating edge is very essential.

In JP 2119198 (Tanaka Kikinzoku Kogyo KK; Filed: 28.10.88; "Outside forming method of printed board ") becomes a special method for the production of V-grooves described with different scratch depth, with which it should be possible to trace to be able to lay very close to the scoring lines or separating edge and after the assembly can separate the individual circuit board without damage of the nearby conductor tracks. You can also use these V-grooves Damage during transport can also be avoided.

From US 5,831,218 (Motorola; Filed: 28.06.96; "Method and circuit board panel for circuit board manufacturing that prevents assembly-line delamination and sagging ") is already known a method and a circuit board with which delaminations and the sagging of printed circuit boards during assembly can be avoided can. In particular, contour punching in combination with a  Both-sided scribing process is described and a formula for calculating the optimal geometric shape of the upper and lower V-groove (V-groove) called.

In US 5,883,356 (Tip Engineering Group; Filed: May 13, 1996; "Laser scoring process and apparatus ") became a process and a plant for the precise scribing of predetermined scribing geometries and scribing depths of spatially shaped workpieces called. Material weaknesses such as those found in airbags, for example Covers are required in the automotive field.

The aim of the present invention is now to demonstrate the Achieve requirements, or the shortcomings described avoid.

The invention is therefore based on the object of an inexpensive type of Generation of scoring lines on both sides of almost any geometric design and maximum process accuracy and process flexibility on printed circuit boards enable and specify a method for producing such scribe lines.

This task is accomplished by using the PCB on both sides acting laser beams solved.

Using innovative laser processing centers based on CO ₂ lasers and / or Nd: YAG-based UV lasers (GSI Lumonics Inc., Ontario, Canada; GS-600; or HITACHI Laser PCB) and / or solid-state lasers based on frequency-tripled 355 nm or frequency-quadrupled 266 nm Nd: YAG laser, so-called UV solid-state laser (ESI - Electro Scientific Industries, Inc .; Portland, OR 97229, USA; Model 5200 laser via drilling system) and / or a copper-bromide laser with 511 or 578 nm wavelength (Klingelnberg Söhne GmbH) and / or based on an excimer laser with 248 nm (LPKF Laser & Electronics GmbH; LPKF MicrolineLaser) and other such systems, the various types of circuit board material can already be processed today.

Lasers in the visible or in the UV wavelength range offer the great advantage that they can also be used to process metallic surfaces. CO ₂ lasers in the IR wavelength range in turn have the advantage of high energy density, which leads to very high speeds in so-called drilling of holes in conventional circuit board materials without metallic layers, and has great advantages especially in the case of small borehole diameters compared to circuit board drilling machines previously used.

The more conventional type of CO ₂ laser works at wavelengths in the 9 to 11 micron range. The advantage of this CO ₂ laser technology lies in the maturity of the laser sources and thus in the availability of high performance and low maintenance or low maintenance costs. The disadvantage of such CO ₂ laser systems is the long wavelength of the laser light and thus the lower possibility of focusing and in particular the low absorption of, for example, metallic surfaces such as copper and / or gold and the like. In the present case of scribe lines, these restrictions are not disturbing, since there is no functional reason to provide such metallic structures in the area of utility contours. The speed of scoring line production, the integral costs and the precision of the scoring line shape and depth usually play a more important role.

The frequency tripled 355 nm Nd: YAG solid state lasers and the Frequency-quadrupled 266 nm Nd: YAG solid-state lasers have been chosen for such Applications proven.

The pulse duration of typically 40 to has proven to be very important parameters 50 ns, the pulse frequency or repetition rate of typically 1 to 20 kHz and the pulse shape, i.e. the operation with different laser modes and / or the Use of panels, highlighted.

In the case of fine scribe lines there is a Gaussian distribution of the laser pulse preferred, because a deliberate, locally very precisely defined weakening of the  PCB should be reached and a fine scoring a better defined Breakline allows.

The use of excimer laser light of, for example, 248 nm again offers higher fineness through the better according to the short wavelength Focusability, however, causes longer process times and higher costs comparable geometries to be machined.

Very important in all these laser processing centers is the fact that the circuit boards to be processed are applied or prepositioned on processing tables, and then the circuit board structure is detected using optoelectronic aids and then, for example, by moving the table in the Y direction and by moving the laser beam using so-called galvano -Optics in the X and Y directions are fed to a very precise machining. The advantage of galvano-optics is the low mass to be moved and thus the high possible dynamics, resulting in a very high processing speed. The deflection range of the galvano-optics is usually limited to a few 40 × 40 mm ² .

Due to the arrangement of laser beam elements on both sides according to the invention no usual positioning tables are used, but fixed ones Tables used. It must be ensured that the Multiple-use circuit board without damaging the surface on the Table surface can be moved back and forth. Roles are advantageous Ball bearing elements, but also air nozzles through which an appropriate air cushion arises between the table surface and the multiple-use circuit board. The Combination of roller ball bearing elements and air cushions together with Sliding plastic pieces are also advantageous to use.

In an inexpensive embodiment, the upper and lower can now Laser beam element can be installed firmly and therefore immovably. On Gripper system can now the multiple-use circuit board according to one  move the specified program between the laser beam elements. This Gripper system can be carried out very inexpensively and with high accuracy are practically no force moments exerted by laser processing and only the inert mass of the circuit board corresponding to the Process accelerations must be taken into account.

The laser beam elements are advantageously coaxial or surrounded by spring elements. Inside are a gas supply and Suction arranged. With an appropriate gas supply, the Machining point can be cooled, resulting in higher laser beam power or removal performance and a thermal Delamination reduced or completely prevented. On the other hand, can the removal of material or the evaporation are removed, which leads to Security of the environment contributes, because in the removal of the most varied Materials vapors can be generated and not into the room air or to be released to the environment. In addition, it can be annoying if vapors occur in the vicinity of the scratch lines deposit on the multi-circuit board surface.

A fully automatic execution of a plant for the production of a Multiple-use printed circuit board with scoring lines on both sides is accordingly replaced by a automatic feeder from a multi-use circuit board stack and / or of corresponding magazines and is always fully automatic a corresponding multiple-use circuit board on a manipulation table Pass gripper system. This gripper system becomes the multiple-use circuit board feed an upper and / or lower optoelectronic registration system and thus detects the multiple-use circuit board according to the defined optical and / or mechanical positioning features. Such optoelectronic Registration systems can be photodiode systems and / or CCD camera systems and can be similar to the laser beam elements in a fixed position be arranged.  

Depending on the required accuracy, predetermined positions can now be recorded and possibly also temperature compensation and / or an error or deviation averaging.

The gripper system can the multiple-use circuit board according to the respective Move the computer program between the laser beam elements, then on a storage table for processed multiple-use circuit boards and move to the waiting position to close another multi-board take.

In a further embodiment, the two can be arranged above and below Laser beam elements using the Galvano-X-Y system. Usually such highly dynamic galvano coordinate tables on relatively small Areas limited from some 30 × 30 to 50 × 50 mm. The advantage of such Execution lies in the high speed, most complex geometrical structures in a very short time what the gripper system with the Multiple-use circuit board without due to the inert mass to be moved cannot efficiently meet the additional high effort.

With such a combination, high speeds and finest Resolutions reached. However, the costs for such a laser galvano X-Y coordinate element and also becomes a much more complex Control and software needed, which ultimately led to considerably higher ones System costs.

In a further typical embodiment, the upper and lower laser beam Element can be powered by just one laser source, which too Cost savings for the entire system leads to additional operating costs can reduce and thus enables a modular system configuration.

The invention will now be described with reference to the drawings. Here further features and results from the drawings and their description Advantages of the invention.

Show it:

Fig. 1 section through a multiple-use circuit board;

Fig. 2 side system of a system according to the invention;

Fig. 3 top view of the system;

Fig. 4 top view of a multi-use circuit board.

In Fig. 1, a multiple-use circuit board 10 with scribe lines 9 is shown. A representation is used which is common today in the circuit board industry and which is based on the use of mechanical cutters. The upper and lower scoring depths 1 , 8 (typically 0.4 mm (+0.15 mm / -0.00 mm)) can now be realized almost arbitrarily when using laser beams and can be controlled by a computer program. The scoring angle 2 (typically 30 to 45 degrees) was previously determined by the availability of scoring tools and can now be reduced to almost 0 ° when using laser beams. However, it can also be made oblique and this can be controlled and defined by means of the pulse shape and the pulse line and the pulse frequency.

The usual minimum distance 3 from the scribe line to the edge of the printed circuit board, usually larger than 2 mm, can be reduced when using laser beams, but is subject to a certain restriction, since the remaining web must be mechanically held in place during the breaking process. With relatively small remaining webs, however, the upper scratch depth 1 can be made deeper than the lower scratch depth 2 . This can reduce the refractive power.

The distance 4 from the scoring line to the scoring line, like the distance 5 from the scoring line to the copper layout, is not subject to any system-related restrictions when using the novel processing using laser beams.

The residual material thickness 6 can now for the first time be set as desired and computer-controlled and, moreover, is not influenced by any wear on the milling tools. The offset 7 from the scribe line to the top occurs when using mechanical milling tools and can be neglected when the upper and lower laser beam elements 11 , 12 are correctly adjusted.

In Fig. 2 is a side view of a plant for producing a multi-copy printed circuit board with both sides of scribe lines 9 is illustrated by means of laser beams.

The multiple-use circuit board 10 is placed on the table 13 by a stack and / or magazine and, in such a pre-positioned manner, is transferred to the xy-θ process system 14 and thus to the computer-controlled gripper system 18 .

So that the underside of the multiple-use circuit board 10 cannot suffer any damage due to the movements on the table 13 , air nozzles 17 carrying the circuit board are present in the table 13 . In simple design variants, such air nozzles 17 can also be replaced by ball bearings and / or plastic sliders. The air nozzles are intended to enable a largely contactless movement of the multiple-use printed circuit board 10 on the table 13 . In addition, the friction is reduced and the travel force required for precise positioning is reduced.

The xy-θ process system 14 now moves the multiple-use circuit board under computer control between the optoelectronic upper and lower elements 19 , 20, and in this way the exact structure data of the multiple-use circuit board are recorded and the origin of the coordinates is determined. Temperature effects can be taken into account in terms of measurement and calculation. Likewise, only 2 reference marks can be optically read and / or several optical features on the top and bottom of the multiple-use circuit board, and such a scribe line program can be optimally matched to the multiple-use circuit board 10 to be processed.

After the optical registration, which can also be carried out in a separate station in the immediate vicinity of the table 13 in order to increase the production capacity, the xy-θ process system 14 moves the multiple-use circuit board between the upper and lower laser beam elements 11 , 12 in accordance with the scribe line program .

In this case, the upper and lower laser beam gas supply / suction / cooling 21 , 22 are preferably used, and in this way the processing areas are cooled at the top and bottom, and the materials removed or evaporated are removed or suctioned off and filtered.

Depending on the embodiment, the upper and lower laser beam elements 11 , 12 can be supplied by only one or two laser sources 15 . A computer 16 controls the entire process and a fully automatic operation can thus be achieved.

In a further embodiment, the upper and lower laser beam elements 11 , 12 can have an xy-galvano deflection unit, and such small and finest and very fast laser beam movements can be carried out in addition to the movements of the xy-θ process system 14 .

After the completion of the upper and lower score line 9 , the xy-θ process system 14 moves the multiple-use circuit board 10 into an output position.

Depending on the degree of automation, this xy-θ process system 14 can now place the multiple-use printed circuit board 10 on a storage station or transfer it to another gripper system.

In Fig. 3 is a plan view of a possible plant for the production of a multi-copy printed circuit board 10 with two-sided scribe lines 9 by means of upper and lower beam-element 11 is shown 12th

In Fig. 4 we schematically shown a multiple-use circuit board 10 with scribe lines 9 . Especially with complex and usually smaller electronic devices, such as mobile telephones and dictation devices and shavers and the like, the aesthetic and ergonomic shape plays a major role and the circuit boards must accordingly be adapted to these boundary conditions.

Since ever more complex electronic functions have to be implemented, the usable wiring and assembly area plays a very important role and, according to the novel double-sided laser processing, almost any geometrical scribe lines can now be realized very cost-efficiently and the refractive power can also be determined by the programmable scribe depth. This also prevents damage to the multiple-use printed circuit boards 10 when it is fitted with electronic components.

Legend

1

Scratch depth above

2

Ritz angle

3rd

Distance from scratch line to edge of PCB

4

Distance from scratch line to scratch line

5

Distance from scratch line to copper layout

6

Residual material thickness

7

Offset scratch line from top to bottom

8th

Scratch depth below

9

Scratch line

10th

Multiple-use circuit board

11

Laser beam element above

12th

Laser beam element below

13

table

14

xy-θ process system

15

Laser source

16

Computer NC control

17th

Air nozzles (ball bearings)

18th

Computer controlled gripper system

19th

Optoelectronic element on top (CCD camera or photodiode)

20th

Optoelectronic element below (CCD camera or photodiode)

21

Laser beam gas supply / suction / cooling above

22

Laser beam gas supply / suction / cooling below

Claims (14)

1. Multiple-use circuit board with scribe lines, characterized in that two-sided scribe lines ( 9 ) are produced by means of laser beams, and that laser beam elements ( 11 , 12 ) which are approximately flush with one another are provided, between which the multiple-use circuit board ( 10 ) to be scribed is movable. 2. Multiple-use printed circuit board according to claim 1, characterized in that the laser beams by means of CO ₂ lasers, Nd: YAG lasers including frequency multiplied, in particular frequency tripled and frequency quadrupled Nd: YAG lasers, excimer lasers and lasers in the visible wavelength range, in particular of copper Bromide lasers are generated and accordingly have correspondingly programmable fine and wide and deep scribe lines ( 9 ). 3. Multiple-use circuit board according to claim 1 or 2, characterized in that the laser sources ( 15 ) are operated pulsed in the range 1 to 30 kHz and can thus be adjusted and optimized to the properties of the circuit board materials used in each case. 4. Multiple-use circuit board according to one of claims 1 to 3, characterized in that the laser beams or laser pulses above and below are of different strengths and scratch lines ( 9 ) of different depths are generated. 5. Multiple-use printed circuit board according to one of claims 1 to 4, characterized in that the upper and lower score lines ( 9 ) are locally or geometrically predetermined and limited to such an extent that a complete separation of the printed circuit board is achieved. 6. Multiple-use circuit board according to one of claims 1 to 5, characterized in that the width and shape of the upper and lower score lines ( 9 ) is computer-aided and thus geometrically different requirements and any curve shapes and any interruptions can be realized. 7. System for producing a multiple-use circuit board with scoring lines on both sides according to one of claims 1 to 6, characterized in that the laser beams by means of CO ₂ lasers, Nd: YAG lasers, including frequency-multiplied, in particular frequency-tripled and frequency-quadrupled, Nd: YAG lasers, excimer laser. Lasers and lasers in the visible wavelength range, in particular copper-bromide lasers, are generated. 8. Plant for producing a multiple-use circuit board according to claim 7, characterized in that the laser sources pulsed in the range 1 to 30 kHz are operated and thus on the properties of the used PCB materials can be adjusted and optimized. 9. Plant for the production of a multiple-use circuit board according to one of the Claims 7 or 8, characterized in that the upper and lower Laser beams or laser pulses are of different strengths and accordingly, different depth lines are created. 10. Plant for the production of a multiple-use printed circuit board according to one of the Claims 7 to 9, characterized in that the upper and lower Laser beams are not exactly aligned with each other, but with a small angle of deviation are arranged in such a way that at direct mutual irradiation no harm to each other Radiation guidance takes place. 11. Production system according to one of claims 7 to 10, characterized in that the multiple-use circuit board ( 10 ) is detected by means of optoelectronic aids and its coordinate system is coordinated and optimized for the respective current program and that the laser beam units ( 11 , 12 ) are fixed are mounted to each other and the respective multiple-use printed circuit boards ( 10 ) are moved in a computer-controlled manner in the x, y and optionally in the θ direction between the laser beams according to a predetermined program. 12. System for producing a multiple-use circuit board according to one of claims 7 to 11, characterized in that the multiple-use circuit board is detected by means of a computer-controlled gripper system ( 18 ) on a table using optoelectronic aids, and that the upper and lower laser system ( 11 , 12 ) cause small movements of the respective laser beam by means of galvano beam deflection units and / or larger distances are caused by the gripper system. 13. System for the production of a multiple-use circuit board with double-sided Scribe lines according to claim 7 to 10, characterized in that the upper and the lower laser beam unit has an automatic focusing device and in the area of the laser beam a circular gas introduction and Has suction and thus achieved cooling of the processing point and a removal of evaporated or removed material reached. 14. Plant for the production of a multiple-use circuit board with double-sided Scribing lines according to claim 7 to 13, characterized in that the fixed table top has a plurality of air nozzles and / or one Has a plurality of ball bearing elements and such the friction and Possibility of damage to the multiple-use circuit board by the computer controlled movement in x, y and θ on the table to a minimum reduced.