The invention relates to a polymer optical interconnect (POI) component. The invention also relates to an electronic device based on or suitable for integration with optical interconnect technology, comprising components including a light source, a light sensor, and an optical interconnect component, more particular to an electronic device wherein the optical interconnect component is a polymer optical interconnect (POI) component.

Improving the performance of a product is a challenge any industry is faced with and which challenge never dies out. This is particularly the case for the electronic industry, already from its early beginnings. Improved performance of electronic devices like computer systems has been achieved, in large part, by downscaling the minimum feature size in the integrated circuit (IC) used in these devices. This allows the basic IC building block, the transistor, to operate at a higher frequency, performing more computations per second. Electrical interconnects are reaching their fundamental limits and are becoming the speed bottleneck in data communications. Downscaling of the minimum feature size also results in tighter packing of the wires on a chip, running to its limitations and introducing other problems. To prevent these problems and overcome the limitations, hybrid optical/electronic interconnects or even fully optical interconnects are being utilized to replace the electrical interconnects using metallic conductors. Optical solutions have been used for wide and local area networks (WAN & LAN) for quite some time already. Now there is also a growing demand for short distance solutions like in backplanes, boards and modules, in chip-to-chip or on-chip interconnections. Owing to costlier technology and lack of fully mature technologies, optics has not yet widespread use in short-distance communications. As optical interconnections move from computer network applications to chip level interconnections, as in chip-to-chip or on-chip interconnections, new requirements for high connection density and alignment reliability have become as critical for the effective utilization of these links. There are still many materials, fabrication, and packaging challenges in integrating optic and electronic technologies. Typically the optical interconnections in the optical interconnect devices will comprise (i) a light source or light transmitter connected to a more distant light source, together denoted as light source, (ii) a receiver which can be a light sensor, or a light transmitter connected to a more distant light sensor, together denoted as light sensor, and (iii) an optical interconnect component. The light source as well as the light sensor can be, individually or both, a chip. The optical interconnect component, which itself is also a light transmitter, might be made of different materials. When it is made of a thermoplastic polymer composition, it is generally referred to as polymer optical interconnect component. The term polymer optical interconnect component will be abbreviated herein as POI-component.

Whereas for long-distance communications glass is the most widely used material, for the short- distance communications in chip level interconnections, new materials are explored, that combine the necessary transparency and light transmittance with the shaping capability, dimensional stability, and low thermal expansion, high heat and optionally moisture resistance. In contrast to earlier misconceptions hereabout, optical communication devices will typically use more power over short distances than an electrical device. More power in combination with small sizes of the components results in even higher temperatures. Different polymers like polymethacrylate (PMMA), cycloolefin copolymer (COC) polynorbornenes (PNB) are used. These materials are either exotic and expensive (PNB) or not thermally stable enough to cope with the processes that the components in the electronic assembly have to undergo in the assembly process.

3C conversion continuous to push integration of additional functionality inside super space limited applications. It is expected that optical interconnects will grow on expense of electrical interconnects, and demand for transparent high temperature plastics will grow.

There is a need for POI-components, suitable for use in an electronic device as an integral part of optical interconnect technology, and materials used therein that are heat resistant and able to provide the POI-components with the necessary transparency, dimensional stability, and thermal stability.

The invention provides a polymer optical interconnect (POI) component comprising a light transmittable part with thickness of at most 3 mm and having a light transmittance of at least 60 %, measured by the method according to ASTM D1003A, wherein the POI component consists of a thermoplastic polymer composition having a melting temperature (Tm-C) of at least 260 ⁰ C and a melting enthalpy of at least 20 J/g, wherein the thermoplastic polymer composition comprises polymeric material comprising a semi-crystalline semi-aromatic polyamide (A) in an amount of at least 50 wt.% and having a melting temperature (Tm-A) of at least 260 ⁰ C, wherein the amount in wt.% and the melting enthalpy in J/g are relative to the total weight of the polymeric material.

It has been found that a POI component with such light transmittance could be made of a thermoplastic polymer composition comprising a semi-crystalline semi-aromatic polyamide with relatively high crystallinity. The POI components can also be made from such compositions containing other components like glass fillers and/or glass fibres, meanwhile retaining a good light transmittance. This is in particular surprising in view of the fact that crystalline polyamides upon moulding tend to become turbid and hazy, in particular with other components present, and generally need to be blended with a relative large amount of amorphous polyamide to become translucent or transparent. The advantage of the POI component made of the said thermoplastic polymer composition comprising said semi-crystalline semi-aromatic polyamide is that it is high heat resistant, has high dimensional stability, and the good moisture resistant. Several of these effects are further enhanced when the composition comprises glass fillers and/or fibres.

With the term "light transmittable" in "light transmittable part" is meant that the part can transmit light in at least a certain extent. In the present invention this minimum extent is defined as a light transmittance of at least 60 %, measured by the method according to ASTM D1003A. Such a light transmittance may be considered to be translucent or transparent, depending on the definition of each of these terms and on the actual light transmittance of the light transmittable part.

With the term light transmittance is herein understood the light transmission measured by the method according to ASTM D 1003 on the light transmittable part as is. Herein the light transmittance is the percentage of the luminous flux transmitted through a specimen compared to the luminous flux incident upon it. There is no correction made for the thickness of the part. - A -

With the term melting temperature is herein understood the melting temperature, measured with the method according to ASTM D3418-97 by DSC in the second heating run with a heating rate of 10°C/min. Herein the maximum peak of the melting endotherm is taken as the melting temperature. With the term melting enthalpy used herein is understood the exothermic energy, measured with the method according to ASTM D3418-97 by DSC in the second heating run with a heating rate of 10°C/min. Herein the area under the melting endotherm is taken as the melting enthalpy.

With a semi-crystalline polymer is herein understood a polymer having a melting enthalpy of at least 5 /J/g. In line with that an amorphous polymer is herein understood to be a polymer having a melting enthalpy of less than 5 J/g.

The term glass transition temperature (Tg) is herein understood the temperature, measured with the method according to ASTM E 1356-91 by DSC in the second heating run with a heating rate of 10°C/min, falling in the glass transition range and showing the highest glass transition rate. The glass transition temperature is determined as the temperature at the maximum peak of the first derivative (with respect of time) of the parent thermal curve corresponding with the inflection point of the parent thermal curve.

The semi-crystalline semi-aromatic polyamide with the melting point of at least 260 ⁰ C will herein also be referred to as polyamide (A).

The melting temperature of the composition mentioned herein, and referred to as Tm-C, is measured on the composition in the POI component, whereas the melting temperature of the semi-crystalline polyamide, referred to as Tm-A, is measured on the polymer. The semi-crystalline semi-aromatic polyamide typically has a glass transition temperature (referred to as Tg-A).

The POI component can be made by an injection moulding process. The light transmittable part may consist of a different composition than the rest of the POI component according to the invention, which multi-composition POI component might thus be produced by a 2K injection moulding process, but preferably the light transmittable part is an integral part of the POI component and the POI component is integrally made by a 1-K injection moulding process. It has been found that the thermoplastic polymer composition having a melting temperature (Tm-C) of at least 260 ⁰ C and comprising the semi-crystalline semi-aromatic polyamide (A), even when comprising glass fillers and/or glass fibres, can be injection moulded to form a moulded product with at least a part thereof having a light transmittance of at least 60 %. This is achieved by an injection moulding process comprising steps wherein the high melting thermoplastic polymer composition comprising the semi- crystalline semi-aromatic polyamide (A) is melt processed and injected into a cavity in a mould, wherein the mould has a temperature (Tmo) of at least 20 ⁰ C below Tg-A, the glass transition temperature of polyamide (A). One further advantage is that the POI component so obtained from a composition comprising glass fibres has a good surface quality with only limited glass fibre print-through, if any. A good surface quality is a critical property of a POI component, in order to prevent scattering of the light and reduction of the yield of the transmitted light. The lower the Tmo, the faster the polymer is quenched and the better the transparency properties are. Preferably Tmo is at least 30 ⁰ C, more preferably at least 40 ⁰ C below

Tg-A. The Tmo values to be applied depend on the actual Tg of polyamide (A) employed. Typical values for the Tmo are 100 ⁰ C or lower, or even 80 ⁰ C and lower.

The results in terms of light transmittance depend further on the type of PPA and the thickness of the moulded part, in particular the thickness of the light transmittable part. The transparency gets even better, when the mould temperature is further below Tg-A and/or the light transmittable part has a lower thickness.

The light transmittable part may have a thickness varying over a large range. Suitably, that part has a thickness of 2-3 mm, or even more, in particular in case glass fibres and glass fillers are absent. Preferably the thickness is at most 2 mm, and more preferred at most 1 mm, even better in the range of 50 - 500 μm, and most preferably in the range of 100 - 200 μm. Handling of such thin parts, even when having relatively small other dimension, is easier in particular when the light transmittable part is an integrated part of a POI component comprising other parts with larger dimensions, for example, having thicker parts forming a kind of window frame around a window screen. Such a POI component is a typical example of a three-dimensional optical interconnect with optical vias. According to the dimensions of the thin part, the mould cavity used in the injection moulding process employed for the production of the POI component according to the invention, preferably comprises a part with a wall to wall distance of less than 3 mm, or so much less according to the desired thickness of the light transmittable part.

The light transmittance of the light transmittable part in the POI- component according to the invention, measured according to ASTM D1003A, is at least 60% and may further vary over a large range. Suitably, the light transmittance is in range of 60-95%, although it might even be higher. With a thickness of 100 μm, low-to-zero glass filler and fibre content, and/or some amorphous polyamide present next to polyamide (A), the light transmittance may be higher than 90%, in particular cases even as high as about 92-94%. Preferably, the light transmittance is at least 65 - 90%, preferably at least 75% and even at least 85 %.

Suitably, the light transmittance in the range of 65 - 95 %, is obtained with a POI-component according to the invention wherein the semi-crystalline semi- aromatic polyamide (A) has a melting temperature (Tm-A) of at least 270 ⁰ C, the semi- crystalline semi-aromatic polyamide (A) is present in an amount of at least 75 wt.%, relative to the total weight of the polymeric material, the thermoplastic polymer composition has a melting temperature (Tm-C) in the range of 270-340 ⁰ C, and the light transmittable part has a thickness of at most 2mm.

The moulded product obtained by the injection moulding process described above, may be only partially crystalline, or even substantially amorphous. The products may be annealed at elevated temperature, or subjected to another heat treatment, wherein the injection moulded product is subjected to a temperature between the Tg and the Tm of the semi-crystalline polyamide. Upon such heat treatment, crystallization might be induced and/or further increased. It has been found that the moulded product retains its light transmitting character in large extent after the product is heated to elevated temperature, despite a significant increase in crystallinity that might have resulted from such a heat treatment. Further advantages of subjecting the moulded product to such a heat treatment step is that water uptake is significantly reduced, and dimensional stability and moisture resistance are further increased. The degree of crystallinity, as well the increase in crystallinity upon annealing or any other heat treatment, is generally reflected in the melting enthalpy. The higher the crystallinity, the higher the melting enthalpy is.

The melting enthalpy of the thermoplastic polymer composition may vary over a large range. Preferably, the thermoplastic polymer composition has a melting enthalpy of at least 30 J/g, more preferably at least 40 J/g, and still more preferably at least 50 J/g, relative to the weight of the polymeric material in the thermoplastic polymer composition. The melt enthalpy may attain values well above 70 J/g, and even as high as 80 J/g and higher, while still having a light transmittable product. The melt enthalpy will also depend on that content of glass fibres and glass fillers. Suitably, for compositions comprising glass fibres and/or glass fillers, e.g. in an amount of 20-40 wt.% relative to the total weight of the composition, the melting enthalpy suitably is in the range of 15 - 60 J/g, relative to the total weight of the thermoplastic polymer composition. The semi-crystalline semi-aromatic polyamide (A) may be any semi- crystalline semi-aromatic polyamide having a melting temperature (Tm-A) of at least 260 ⁰ C. Preferably Tm-A, and likewise Tm-C is in the range of 270-340 ⁰ C, more preferably 290-330 ⁰ C, or even better 310-330°C. Suitably, the said semi-crystalline semi-aromatic polyamide is a blend of different semi-crystalline polyamides. In that case the melting temperature of the blend shall still be at least 260 ⁰ C and preferably be in the range of 270-340 °C.

The semi-crystalline semi-aromatic polyamide can be a polyamide with repeating units derived from dicarboxylic acids and diamines wherein either the dicarboxylic acids, or the diamines, or both, comprises aromatic components while the remainder comprises aliphatic dicarboxylic acids and/or diamines, which can linear, branched, or cyclic, and/or arylaliphatic dicarboxylic acids and diamines.

Examples of suitable aromatic dicarboxylic acids are terephthalic acid and isophthalic acid.

Preferably, the semi-crystalline semi-aromatic polyamide comprises repeat units derived from terephthalic acid as the dicarboxylic acids. Examples of suitable aromatic diamines are meta-xylylene diamine and para-xylylene diamine. Examples of suitable semi-crystalline semi-aromatic polyamides include homopolyamides like PA7T, PA9T, PA10T and PA12T having a melting temperature in the range of 270-350 ⁰ C, and copolyamides of PA4T, PA5T, PA6T and /or PA8T , with for example PA7T, PA9T, PA10T, PA 11T PA12T, PA6, PA66, and/or PMXD6. The homopolymers of PA4T, PA5T, PA6T and PA8T have a melting temperature above 340 ⁰ C, but the copolymers can be formulated such as to have a melting temperature below 340 ⁰ C. Suitable copolyamides include PA10T/6T, PA9T/M8T (wherein M8 = 2-Methyl octamethylene diamine), PA6T/5T, PA6T/M5T (wherein M5 = 2- Methyl pentamethylene diamine), and PA6T/10T. For further examples of suitable semi- crystalline semi-aromatic copolyamides see Kunststoff Handbuch, (Carl Hanser Verlag 1998) Band 3/4 Polyamide chapter 6.

Preferably, the semi-crystalline semi-aromatic polyamide has a melting temperature in the range of 290-335 ⁰ C, more preferably in the range of 310 - 330 ⁰ C. With a higher minimum melting temperature the film has better thermal and dimensional properties. With a lower maximum melting temperature the thermoplastic polymer composition can be more easily processed into the transparent film or the extrudate product. A higher melting temperature can be accomplished e.g. by using a higher amount of terephthalic acid and/or alicyclic or aromatic diamines, or short chain aliphatic diamines. The person skilled in the art can adapt the melting point using common general knowledge and routine experiments.

In a preferred embodiment the semi-crystalline semi-aromatic copolyamide consists of repeat units derived from:

(a) 25-45 mole % terephthalic acid,

(b) 5-25 mole % of an aromatic dicarboxylic acid different from terephthalic acid, and/or an aliphatic dicarboxylic acid,

(c) 5-30 mole% of an diamine chosen from the group consisting of ethylene diamine, trimethylene diamine, tetramethylene diamine and pentamethylene diamine,

(d) 20-45 mole% of a diamine comprising at least 6 C-atoms, and optionally (e) 0 -10 mole % of one or more aminocarboxylic acids and or lactams, and

(f) 0 - 3 mole % of compounds being mono-functional or tri-functional in amino and

/or carboxylic acid groups; wherein the mole % of each of a-f is relative to the total of a-f, and the total of a-f is 100%.

It has been found that a translucent or transparent product according to this embodiment can easily be produced, using moderate hot water moulding conditions, i.e. the temperature of the mould was controlled by hot non-boiling water, eliminating the need to apply high pressures. Even if the said semi-crystalline polyamide had a melting temperature as high as 325°C, and was used in a composition comprising glass fibres in relative large amount, but without a second polymer, such as an amorphous polyamide, transparent or translucent products were obtained. The light transmittance was also retained by large after heating of the product, e.g. after 3 times going through a lead free reflow soldering profile, despite crystallization induced by and occurring upon said heating.

Preferably, in the said embodiment the semi-crystalline polyamide has a melting temperature in the range of 290-335 ⁰ C, more preferably in the range of 300- 330 ⁰ C, and even better 310-330 ⁰ C. A higher melting temperature can be accomplished e.g. by using a higher amount of component (a) and or component (c) in the semi- crystalline semi-aromatic copolyamide in the above embodiment.

The components a-f in the said embodiment are preferably present, either individually or in combination with each other, in the following amounts: (a) 35 - 45 mole %; (b) 5 - 15 mole %; (c) 10 - 25 mole %; (d) 25 - 40 mole %; (e) 0 - 5 mole %; and (f ) 0 - 1 mole %; wherein the mole % of each of a-f is relative to the total of a-f. Higher amounts of (a) and (d), relative to respectively (b) and (c) result in better processing for the polymer in combination with better high temperature properties.

In another preferred embodiment, the semi-crystalline semi-aromatic copolyamide polymer has a density of at least 1.15, preferably at least 1.20 or even 1.25. A higher density results in a higher refractive index, which is advantageous when the POI-component is used, for example, as a lens. In particular the composition free of glass fibres and fillers is suited for preparing lenses.

Analogously, for POI components in direct contact with glass fibres for connection to remote light sources and/or light sensors, it is preferably to have a thermoplastic polymer composition with a density of at least 1.20, preferably at least 1.30 or even 1.40. The advantage of a higher density is that loss of light at the POI component-glass fibre interface is reduced. Such a higher density can be achieved with a higher content in glass fibres and fillers and in particular with a semi-crystalline semi- aromatic copolyamide polymer having a higher density.

The thermoplastic polymer composition used in the POI component may comprise a second polymer next to the semi-crystalline semi-aromatic polyamide. The second polymer may be any polymer, or a combination of polymers, provided the weight ratio between the second polymer and the semi-crystalline semi-aromatic polyamide is at most 1 , and the amount of the second polymer is further limited such that the melting temperature (Tg-C) of thermoplastic polymer composition remains at least 270 ⁰ C, and the light transmittance of the light transmittable part of the POI component remains at least 60 %, measured by the method according to ASTM D1003A.

Preferably the second polymer is chosen from polymers that are miscible with polyamides, such as other polyamides, and apart from that, it is preferably used in a limited amount, if any. The second polymer (B) may suitably comprise, or even consist of an amorphous semi-aromatic polyamide and/or a semi-crystalline aliphatic or semi-aromatic polyamide having a melting temperature below 270 ⁰ C.

The use of such an amorphous or low melting semi-crystalline polyamide has the advantage of being well compatible with the semi-crystalline polyamide (A) while easing the processing of the semi-crystalline polyamide at temperatures above the melting temperature for making the POI component according to the invention. The amorphous polyamide further has the advantage that the light transmittance will be enhanced. An example of such a lower melting semi-crystalline polyamide that can suitably be used in the present invention is polyamide-6, or polyamide 66. Suitable amorphous polyamides include amorphous polyamide 6I/6T copolyamides.

The amounts of the second polymer (B) that can be used depend on the nature of the semi-crystalline semi-aromatic polyamide (A) and the second polymer (B), being either both semi-crystalline or the first one semi-crystalline, and the other amorphous, the melting temperature of the semi-crystalline polymers and the compatibility between the two polymers. In particular in combination with a higher melting semi-crystalline polyamide, for example with a Tm-A in the range of 300-340 ⁰ C, the amount of the second polymer (B) may be larger, while still retaining a product with good properties. In combination with a somewhat lower melting semi-crystalline polyamide (A), for example with a Tm-A in the range of 280-300 ⁰ C, the amount that can be used but can still be substantial, meanwhile retaining the melting temperature Tm-C of the thermoplastic polymer composition in the in the range of 270-340 °C. With a semi-crystalline polyamide (A) with a Tm-A in the range of 270-280 ⁰ C, the presence of a second polymer will be critical for the melting temperature Tm-C of the thermoplastic polymer composition, and the amount the second polymer ris preferably very low if not absent at all.

Suitably, the second polymer is present in an amount of 1 - 40 wt.% or, more strictly 10 -25 wt.%. Preferred amounts for the second polymer, if any, are in the range of 0 -25 wt.% and even better 0 -10 wt.% Herein the weight percentage, as throughout this specification, are relative to the total weight of the thermoplastic polymer composition, unless expressly noted otherwise.

A lower amount of second polymer is advantageous for better mechanical and thermal properties. The better properties can be in better creep resistance, higher mechanical strength, and better dimensional stability at elevated temperature and/or under humid conditions.

The composition used in the POI component may comprise glass fibres and glass fillers. The glass fibres may any auxiliary glass fibre that is used in polyamide moulding compositions. The glass fillers may comprise both glass spheres and/or glass flakes. It may also be any modification thereof that is suitable for use in molding compositions. Suitably, these fibres and fillers have a cross section with a maximum thickness of at most 20 μm, preferably at most 15 μm, and suitable at least 100 nm, preferably at least 1 μm.

The glass fibres and glass fillers may be present in an amount varying over a large range, which may be as high as 50 wt.%, relative to the total weight of the thermoplastic polymer composition, or even higher. Preferably, the amount is at most 40 wt.%, and preferably in the range of 5-30 wt.%. The composition used in the POI component may comprise other additives, which may be any auxillliary additive used on polyamide moulding compositions, provided that the additive or additives are selected from such grades and used in such an amount that the light transmittance of the light transmittable part of the POI component remains at least 60 %, measured by the method according to ASTM D1003A.

Suitable, the thermoplastic polymer composition comprises at least one additive chosen from the group consisting of plasticizers, stabilizers, dyes, optical brighteners, coloring agents, lubricants, and nano-fillers. Preferably, the additive comprises heat stabilizers and/or nano-fillers.

Suitably, the additive or additives are present in a combined amount in the range of can O -10 wt.%. Preferably the amount is in the range of 0.01 - 2 wt.%, more preferably 0.1 -1.0 wt.%. Herein the wt.% are relative to the total weight of the composition. In a suitable embodiment of the POI-component according to the invention, the thermoplastic polymer composition consists of

(A) 40 - 95 wt.% of the semi-crystalline semi-aromatic polyamide,

(B) 0 - 40 wt.% of a second polymer

(C) 5 - 40 wt.% of glass fillers and/or fibres (D) 0.01 - 10 wt.% of at least one additive wherein the wt.% are relative to the total weight of the thermoplastic polymer composition (and the combined amount of A, B, and C is 100%).

This embodiment may be combined with any other feature, and preferred features of the POI component according to the invention described herein. The invention also relates to a process for preparing the POI- component according to the invention, or any preferred embodiment thereof. This process comprises steps wherein a thermoplastic polymer composition comprising a semi-crystalline semi-aromatic polyamide (A) having a melting temperature (Tm-A) of at least 270 ⁰ C and a glass transition temperature (Tg-A), is melt processed and injected into a cavity in a mould, wherein the cavity comprises a section having a maximum width of 3 mm and the mould has a temperature (Tmo) of at least 20 ⁰ C below Tg-A. The process may typically comprise a demoulding step wherein the so formed injection moulded part is taken out of the mould.

The process may advantageously comprise a further step wherein the injection moulded product, after demoulding, is subjected to a temperature between the glass transition temperature Tg and the melting temperature Tm of the semi-crystalline semi-aromatic polyamide, thereby inducing crystallization and/or further enhancing the crystallinity.

This process is not only suited for preparing a POI component, but for any injection moulded product comprising a part having a light transmittance of at least 60 %.

The process may also be used to mould the POI component directly onto another component intended for use in optical interconnect device.

The invention also relates to the injection moulded product obtainable with the said process. The injection moulded product may have any further specific characteristic, or combination thereof, as specified above for the POI component and any preferred embodiment thereof.

The use of the POI component according to the present invention is not limited to a particular application. It may be used in optical interconnect technology, wherein a transmitter component is positioned between a light source and a light sensor. The POI may also be used as a housing for LED indicators or cover shield for an LCD display in mobile phones and other applications.

It may be used in fully optical interconnects as well as in hybrid optical/electronic interconnects. In electronic systems, such as PCBs, often a surface mounting technology (SMT) involving the use of heat soldering is applied. The POI component according to the invention has the advantage that is can withstand very well the elevated temperatures applied in such SMT processes. As such, the POI component can also be the connector or socket or part of those.

The POI component may also be used in chip-to-chip as well as in on- chip interconnections.

It may well be a three-dimensional interconnect with one or more optical vias. The three-dimensional interconnect may very well constitute a housing for th e chip or one of the chips, with the optical via, i.e. the light transmittable part, facing directly towards the light transmitter channels or light transmitter receiver. The good dimensional stability of the POI component according to the invention also attributes to a good alignment of the various components in the optical interconnect assemblies. The POI component can also be used as an optical connector for connecting an optical waveguide, such as optical fibers, with another optical waveguide, an optical diode or an optical sensor.

Optical interconnect assemblies or devices comprising the POI component according to the invention may be used in for example optical digital computers, switches, relays, printed circuit boards.

The injection moulded product with the light transmittable part according to the invention or made by the process according to the invention may also be used in optical sensors. The injection moulded product may also be used in any light emitting application, where the light source is shielded by a light transmittable shield. Suitably, the injection moulded product is used in lighting elements, such as LED reflector housings, scramblers, primary or a secondary optics of a LED light source, lamp bases, LED substrates, LED housing or module, lamp mounting elements, reflector plates, reflectors of automotive lighting systems, sensor housing.

The invention is further illustrated with the following examples.

Material

Polyamide composition, consisting of a semi aromatic copolyamide, 69.5 wt.%, glass fibres, 30 wt.%, and an additive composition, 0.5 wt.%,. The semi aromatic copolyamide was a polyamide 6T/46, ratio about 75/25, Tm 305 ⁰ C, Tg 117 ⁰ C, RV 1.9. The glass fibres were a standard type of glass fibres for polyamides. The additive composition comprised auxiliary processing aids and heat stabilizers.

Moulding

The polyamide composition was fed to an extruder, heated and melt- processed at a temperature of 330 ⁰ C and injected into a mould cavity used for making casings of a switch. The mould had a temperature of 70°C. The cavity and the corresponding casing had lateral dimensions of about 5x5 mm, a planar part with a thickness of about 1 mm and lateral parts with a thickness of about 2 mm. The casing was taken from the mould and allowed to cool to room temperature.

Properties The resulting casing was translucent while the planar part had a light transmittance of about 70%.