Siemens Aktiengesellschaft

Siemens Production & Logistics Systems Ag

Eddy Roelants

Hubert De Steur

Marcel Heerman

Hans Juergen Mayer

Alexander Kilthau

Andre Kletti

Jozef Van Puymbroeck

Hans-Fr Schmidt

Helmut Hadwiger

Stefan Lesjak

Wei Pan

Udo Wiggermann

S&eacute;bastian Edm&eacute;

Marc Van Biesen

Sebastien Edme

Alex Schreiner

Petra Mitzinneck

Hans J&uuml;rgen Mayer

Milan Prochazka

Oliver Thuerk

Leo Higgins

Otto M&auml;rten

Christian Overmann

Martin Wehner

For processing electric circuit substrates, a laser source with a diode-pumped. quality-controlled, pulsed solid-state laser is used. The laser is able to emit laser radiation with a wavelength between 266 nm and 1064 nm, a pulse repetition rate between 1 kHz and 1 MHz and a pulse length of 30 ns to 200 ns with an average laser power between 1 W and around 5 W. Pre-specified operating modes can be set via a controller, depending on an area of application, with the appropriate different combinations of laser power and repetition rate. Thus, the same laser can optionally be used to perform a drilling operation, an etch removal operation or an exposure operation. Using a galvo mirror deflector unit that can also be controlled via the deflection unit, the laser beam may be deflected on the substrate in accordance with the relevant operating mode.

Arrangement and method for processing electrical substrates using lasers

A method and an apparatus are for rapidly processing dielectric substrates using laser beams. A pulsed laser beam having a pulse repetition frequency greater than approximately 50 kHz and having pulse lengths shorter than approximately 200 ns is used for this purpose. Given a suitable choice of the parameters which characterize the processing laser beam, it is possible to ensure both a high throughput of bored holes and a high hole quality. With the use of a Q-switched CO laser, a wavelength of approximately 9.2 &mgr;m and a pulse energy of approximately 0.7 mJ are used. As a result, by way of example, 500 holes per second can be bored into an LCP substrate having a thickness of 0.4 mm. The high throughput and the simultaneously high hole quality are a consequence of the wavelength chosen, the short pulse lengths, the high repetition rate and the pulse energy that is likewise high compared with conventional laser processing apparatuses in the area of electronic fabrication.

Method and apparatus for laser processing

A method and device can be used to pattern both regions of a printed circuit board which are provided for coarse conductor structures and regions which are provided for relatively fine conductor structures of the printed circuit board. In each case, this can be done via laser processing. Both regions are firstly coated with a continuous metallization layer and covered with an etch resistor. The coarse conductor structures are predefined with a laser beam with a relatively long wavelength by exposing the metal surfaces which are not required. In addition, the fine conductor structures are also pre-shaped by processing the etch resist with a laser beam with a relatively short wavelength. Then, in a common etching process, all the exposed surface regions of the metal layer are etched away so that only the coarse and fine conductor track structures which are covered by the remaining etch resist are left. As a result of the removal of the rest of the etch resist, the surfaces of the conductor tracks which are produced are then exposed.

Method and apparatus for structuring printed circuit boards

When holes are being drilled in an electric circuit substrate, a laser beam is moved on concentric circular tracks in the region of the hole to be drilled. The transition from one circular track to the next takes place in each case on an arc that departs approximately tangentially from the circular track last traversed and nestles approximately tangentially against the circular track newly to be described in such a way that in each case the starting point of a new circular track is offset by a prescribed angle from the starting point of the preceding circular track.

Method for drilling holes in a substrate

To calibrate the optical system of a laser machine having a laser source, a deflecting unit and an imaging unit, firstly a first sample plate is arranged in the focal plane of the imaging unit, with prescribed grid points being marked by the laser beam. After that, the marked points are measured by means of a camera, and their position values are compared with the prescribed position values of the target points, in order to derive first correction values from this and store them. After that, a second sample plate is arranged in a second calibrating plane, at a distance from the focal plane, and is targeted by the laser beam and provided with markings. The second sample plate is measured by the camera, and the measured positions of the markings are compared with the positions of the target points, in order to derive second correction values and store them. From the stored first and second correction values of the two planes, correction values can then be determined by interpolation for arbitrary target points in the spatial region between the focal plane and the second calibrating plane and be used for the activation of the deflecting unit.

Method of calibrating the optical system of a laser machine for processing electrical circuit substrates

In a method for the laser drilling of holes in a circuit substrate with the aid of a perforated mask, a laser beam is moved in the region of the perforated mask on a circular path. The center point of the region lies concentrically with respect to the set position of the respective hole in the mask. Further, the diameter of the region is smaller than the diameter of the hole. At the same time, the diameter of the laser beam spot is chosen to be large enough that it always covers the center point of the perforated mask during the circular motion. As a result, an energy distribution of the laser energy, which is as uniform as possible, is achieved in the region of the perforated mask.

Method of laser drilling

To drill micro-holes in a multi-layer substrate having a first metal layer and at least one second metal layer, and having a dielectric layer arranged between two metal layers, use is made of a solid-state laser. The beam of the laser, in a first operation, ablates the first metal layer and, in a second operation, ablates the dielectric layer down to the second metal layer. In the first operation, the laser beam is set to a repetition frequency of at least 15 kHz, focused onto the first metal layer and moved in a circle corresponding to the diameter of the desired hole, in such a number of passes until this metal layer is cut through. Then, in the second operation, the laser beam is set to a preferably lower repetition frequency, directed out of focus onto the dielectric layer exposed in the hole and moved, with a circumferential velocity which is higher compared with the first operation, in one or more concentric circles, until the dielectric layer is ablated in the hole region. The effective energy density in the second operation is selected, by setting the defocusing and the circumferential velocity, in such a way that the effective energy density lies below the threshold for ablation of the second metal layer.

Method for drilling micro-holes with a laser beam

A metal layer, an etching resist and a photoresist are successively applied to an electrically insulating substrate. Whereupon the photoresist is patterned by photolithography in such a way that it covers a pattern of the later coarse conductor structures and the entire region of the later fine conductor structures. After the uncovered etching resist has been stripped, the photoresist is removed, whereupon the etching resist is patterned with the aid of a laser beam in such a way that it has the pattern of the fine conductor structures. The coarse conductor structures and the fine conductor structures are then formed in a common etching process.

Method for producing wiring configurations having coarse conductor structures and at least one region having fine conductor structures

For the laser machining of organic materials, a laser with the below listed parameters is used. The laser has a wavelength of 300 nm to 1200 nm, a pulse width of <50 ns and a pulse frequency of >20 kHz. To increase a degree of absorption and consequently the machining rate, additives with good absorption of the laser beam with the respectively chosen wavelength are admixed with the organic materials.

Method for the laser machining of organic materials

When a laser beam is focussed onto a substrate for the purpose of substrate processing, the optical units such as beam expander, deflecting unit, and optical imaging device prescribe the range of depth of focus in which it is possible to work with a minimum spot size. The difficulty of boring thin holes, especially in thick substrates, is overcome with a second laser beam that is widened via a second beam expander and likewise focused onto the substrate via the deflecting unit and the optical imaging device. The position and the length of the second range of depth of focus can be varied by selecting the magnification of the second beam expander or by maladjustment. Thin holes can also be bored into thick substrates by using the two laser beams one after another.

Device and method for processing substrates

A solder resist and a positively-acting photoresist are successively applied on a surface-wide basis onto a printed circuit board, whereupon the photoresist is selectively exposed and developed in the region of plated-through holes and/or solder pads of a printed conductor pattern carried on the printed circuit board, preferably with the assistance of laser beams. Subsequently, the solder resist is stripped in the regions not protected by the photoresist, i.e. in the regions of plated-through holes and/or solder pads and, as a last step, the remaining photoresist is likewise stripped. The method is particularly suited for the application of a solder resist layer onto three-dimensional printed circuit boards since traditional mask techniques for structuring the solder resist cannot be employed with respect to three-dimensional printed circuit boards.

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Bruegge, Belgium

Eddy Roelants