Additive for LDS plastics

Abstract

The present invention relates to an LDS-active additive for LDS plastics, to a polymer composition comprising an additive of this type, and to an article having metallized conductor tracks in which a polymeric basic body of the article or a polymeric coating on a basic body comprises an LDS additive of the said type.

Claims

1. A method of preparing a polymeric composition for use in laser direct structuring, said method comprising adding to the polymeric composition a pigment which comprises doped tin dioxide as a laser direct structuring additive, wherein the doping consists of one or more non-metallic elements.

2. The method according to claim 1, wherein the doping is selected from one or more of the elements fluorine, iodine, bromine, chlorine, boron, phosphorus and nitrogen.

3. The method according to claim 1, wherein the tin dioxide is doped with fluorine.

4. The method according to claim 1, wherein the pigments consist of the doped tin dioxide.

5. The method according to claim 1, wherein the pigments each consist of a substrate and a coating located thereon, and the doped tin dioxide is present in the coating.

6. The method according to claim 5, wherein the substrate has an isotropic or anisotropic form.

7. The method according to claim 5, wherein the substrate consists of a silicate material, zinc sulfide, titanium dioxide or potassium titanate and has a coating which comprises said doped tin dioxide.

8. The method according to claim 1, wherein the doped tin dioxide has a percentage molar proportion of doping elements of 1 to 20 mol-%, based on the total molar mass of tin and doping element(s).

9. The method according to claim 1, wherein the pigments have a particle size in the range from in each case 0.001 to 100 m.

10. The method according to claim 1, wherein the pigments are present in the polymeric composition in a proportion in the range from 0.1 to 30% by weight, based on the total weight of the polymeric composition.

11. The method according to claim 1, wherein the polymeric composition comprises at least one organic polymeric plastic and optionally fillers and/or colorants besides the laser direct structuring additive.

12. The method according to claim 1, wherein the doped tin dioxide is present in the polymeric composition in a mixture with further conventional laser direct structuring additives.

13. A polymeric composition comprising at least one organic polymeric plastic and a laser direct structuring additive, where the laser direct structuring additive comprises pigments which comprise doped tin dioxide, where the doping consists of one or more non-metallic elements.

14. A polymeric composition according to claim 13, wherein the laser direct structuring additive is present in the polymeric composition in a proportion of 0.1 to 30% by weight, based on the total weight of the polymeric composition.

15. A polymeric composition according to claim 13, wherein the polymeric composition is a thermoplastic or thermosetting material.

16. An article having a circuit structure produced in a laser direct structuring process, consisting of a plastic basic body or a basic body having a plastic-containing coating and metallic conductor tracks located on the surface of the basic body or coating, where the plastic basic body or the plastic-containing coating of the basic body comprises a laser direct structuring additive which comprises pigments which comprise doped tin dioxide, where the doping consists of one or more non-metallic elements.

17. The method according to claim 1, wherein the doping is a combination of fluorine and nitrogen or a combination of fluorine and phosphorus.

18. The method according to claim 5, wherein the pigments comprise the doped tin dioxide in an amount of at least 10% by weight, based on the weight of the entire pigment.

19. The method according to claim 5, wherein the coating has a geometrical thickness in the range from 1 to 300 nm.

20. The method according to claim 1, wherein the pigments are present in the polymeric composition in a proportion in the range from 0.5 to 15% by weight, based on the total weight of the polymeric composition.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1: shows the absorption curve of a plastic plate having a content of 0.1% by weight of FTO

(2) The present invention will be explained below with reference to examples, but will not be restricted thereto.

EXAMPLE 1

(3) A) Preparation of a Pigment Having an FTO (F,SnO.sub.2) Layer on a TiO.sub.2 Support Material: The pigment is prepared in accordance with Example 1 of DE 4237355 A1: 156.7 g of tin(II) fluoride are dissolved in 3 l of water. 80 g of titanium dioxide particles (particle size 100-300 nm) are added to this solution with vigorous stirring. The dispersion is heated to 85 to 90 C. A solution of 260.5 g of tin tetrachloride in 943 ml of ethanol is added dropwise at a pH of 3.5 to 4.5. During the addition, the pH is kept constant by simultaneous addition of 5% ammonia solution. When the SnCl.sub.4 addition is complete, the temperature is kept constant for a further hour, and the mixture is subsequently filtered. The filter cake is washed a number of times with water. The product is dried and calcined at 500 C. The calcination duration is 10 minutes.

(4) B) Preparation of a Pigment Comprising FTO The pigment is prepared in accordance with Example 2 of DE 4006044 A1: 250 g of tin(II) oxide, 14.75 g of tin(II) chloride and 14.75 g of tin(II) fluoride are mixed intimately with one another by grinding for 10 minutes in a mortar mill. The substance mixture obtained in this way is calcined at 300 C. in a corundum dish for 1 hour. After cooling, the pale-grey, electrically conductive, doped tin oxide obtained in this way is ground for a further 10 minutes in a mortar mill.

(5) Use as LDS Additive:

(6) 5% by weight of the LDS additive prepared in accordance with procedure B) are incorporated into PC/ABS (Xantar C CM 406, Mitsubishi Engineering Plastics) by means of a co-rotating twin-screw extruder. The extrudate is strand pelletised and subsequently dried at 100 C. for 4 hours. Test plates having the dimensions 60901.5 mm are then injection-moulded in an injection-moulding machine.

(7) The test plates are treated by means of a 1064 nm fibre laser with different laser powers and frequencies in the range from 3-16 W and 60-100 kHz in test fields in a grid in such a way that slight material ablation takes place with simultaneous carbonisation of the treated area. Metallisation with copper is subsequently carried out in a commercially available reductive copper bath (MID Copper 100 B1, MacDermid). The metallisation properties are assessed with reference to the structure of the copper layer on the substrate. The plating index (according to MacDermid) is indicated, which is obtained from the quotient of the built-up copper layer of the test material and the built-up copper layer of the reference material. The reference material used is PBT test plates having a proportion of 5% by weight of copper spinel (reference).

COMPARATIVE EXAMPLE 1

(8) Analogously to Example 1, 5% by weight of a pigment are incorporated as LDS additive into the PC/ABS test plates, where the pigment has an antimony-doped tin dioxide layer on a mica substrate. The pigment is a product from Merck KGaA which is commercially available under the name Iriotec 8825.

(9) TABLE-US-00001 Plating index Cu spinel Comp. Laser setting (reference) Ex. 1 Ex. 1 3 W/60 kHz 0.41 0.00 0.00 4 W/60 kHz 0.56 0.00 0.00 5 W/60 kHz 0.65 0.00 0.00 6 W/60 kHz 0.71 0.00 0.15 8 W/60 kHz 0.69 0.15 0.65 4 W/80 kHz 0.65 0.00 0.00 6 W/80 kHz 0.83 0.00 0.00 8 W/80 kHz 0.76 0.00 0.36 10 W/80 kHz 0.73 0.00 1.02 12 W/80 kHz 0.70 0.16 0.93 14 W/80 kHz 0.63 0.54 0.81 6 W/100 kHz 0.88 0.00 0.01 8 W/100 kHz 0.79 0.00 0.18 10 W/100 kHz 0.70 0.00 0.86 12 W/100 kHz 0.68 0.00 0.93 14 W/100 kHz 0.72 0.34 0.85 16 W/100 kHz 0.67 0.75 0.83

(10) The experiments show that the fluorine-doped tin dioxide employed in accordance with the invention as LDS additive exhibits significantly better values with respect to the metallisability both in the range of the laser parameters and also with respect to the nominal values of the plating index than the mica flakes in accordance with Comparative Example 1 which are coated with antimony-doped tin dioxide, is comparable with Cu spinel (reference) in the peak values and exhibits very good metallisation values, in particular at relatively high laser power.