Patent Description:
For some opto-electronic applications, the wavelengths of the beam emitted by the laser chip must be controlled precisely. As the wavelength of the laser is temperature dependent. Therefore, the temperature of the laser should be stabilized within a narrow temperature range. To achieve this, it is known to use a thermo-electric cooler (TEC). The TEC may be included within the housing for the laser diode, such as a transistor outline (TO) package. TECs may be used in tandem with directly modulated Lasers (DML) for midrange distances. The DML is lower in costs as external modulated laser (EML). However, many laser driver ICs are driving the DML with differential signals. In this case, the header needs two RF signal lines. These two signal lines should preferably have a characteristic impedance Z<NUM> = <NUM> Ohms or <NUM> Ohms to avoid signal degradation from reflections others then from the DML.

Further, the TEC has a hot and a cold side. The hot side is connected to the header for heat dissipation. The DML is mounted on the cold side. The cold side should be thermally isolated from the hot side to prevent thermal feedback and a self-heating effect. On the other hand, two RF lines must be connected to the DML. One well known concept is to use two separate RF lines. Each RF line comprises a small printed wire board (pedestal submount) to bring the signal to the DML inside the header. Each pedestal submount may be mounted on a separate pedestal. Typically, the pedestals and the eyelet or base of the header are made in one stamping process as one piece.

In current designs, the RF line may be a ground referenced microstrip line with the signal line on the top side and the ground on the bottom side of the pedestal submount. To connect the DML mounted on a carrier on the cold side of the TEC bond wires are used, because of their very low thermal conductivity. To get access to the ground for the bond wire interconnection, two through hole vias may be used in each pedestal submount. The vias provide interconnection from the bottom side to the top side of the pedestal submount. Using two vias enable a bond wire configuration of ground - signal -ground (GSG) which has much better RF performance as the simple ground-signal configuration.

Because the two RF lines reach the DML from opposite directions, the two pedestal submounts have different metal patterns, which complicates the assembly. Therefore, it is an object of the invention to provide a design for a header which facilitates the assembly and nevertheless provides good RF-performance. This object is achieved by the subject matter of the claims. Accordingly, a header for an electronic component is provided, comprising a base with at least two electrical feedthroughs, each comprising a feedthrough pin extending through the base and being electrically isolated to the base within the feedthrough. The header further comprises at least one pedestal connected to the base, and two submounts. Each submount comprises a carrier or substrate with a structured conductor plating, with the conductor plating comprising at least two conductor traces. One of the conductor traces of each submount is electrically connected to one of the feedthrough pins. The submounts are equally formed. However, the submounts are mounted in different orientations to enable contacting the electronic device from opposite directions.

It is advantageous, if two pedestals are provided. Then, each of the pedestals carries one of the submounts and the pedestals are connected to the base with a gap in between. Within this gap, a mount with the electronic device can be positioned and fastened to the base.

<CIT> describes a device of this type, in accordance with the pre-characterizing part of claim <NUM>.

A related package is disclosed by <CIT>.

A header in accordance with embodiments of the present invention is defined in claim <NUM>.

In a header of this type, the submounts are mounted onto the at least one pedestal so that the respective ends of those conductor traces that are connected to the feedthrough pins face each other. The conductor traces connected to the feedthrough pins are typically the signal carrying conductors. Thus, using a configuration where the ends distal to the feedthrough pins face each other, the distances for the connection to the electronic device can be reduced.

The pattern of the structured conductor plating of the submount has a mirror symmetry. This enables to use submounts mounted with different ends pointing towards the base and therewith have the ends of the conductor traces facing each other. Thus, according to a preferred embodiment, the submounts have two opposite ends and are mounted with one end facing the base and wherein a symmetry plane of the mirror symmetrical conductor plating is located between the ends. In particular, the submounts may have two opposite ends, in particular ends that are distinguishable with respect to each other, wherein one of the submounts is attached to the pedestal with one end facing the base and the other submount is attached to the pedestal with the opposite end facing the base. This way, the left and right submounts are of the same type but are simply mounted with one of the submounts turned around by <NUM>°.

In the following, the invention will be described in more detail with reference to the accompanying drawings.

The header <NUM> as shown in <FIG> comprises a base <NUM> with two or more electrical feedthroughs <NUM>. The feedthroughs serve to transmit electrical signals in or out of the header <NUM>. Each feedthrough <NUM> comprises a feedthrough pin <NUM> that extends through the base <NUM> and is electrically isolated thereto. For this purpose, the base <NUM> comprises eyelets <NUM> filled with an insulating material, preferably glass, in which the feedthrough pin <NUM> is fixed. In a preferred embodiment, the pin <NUM> has a diameter in a range from <NUM> to <NUM>. The projection of the pin over the side of the base <NUM> carrying the pedestals <NUM> ("post height") may be in a range of from <NUM> to <NUM>. According to an example, the feedthrough pin <NUM> has a diameter of <NUM> and a post height of <NUM>.

Two pedestals <NUM> are connected to and protrude from the base <NUM>. Without restriction to the specific example as shown, the pedestals <NUM> are arranged in a distance with a gap <NUM> in between. The gap <NUM> serves to accommodate further elements, in particular an assembly for carrying the electronic device as described further below.

On each of the pedestals <NUM>, a submount <NUM> is attached. Generally, without restriction to features of the specific exemplary embodiments as shown in the figures, it is contemplated that the pedestals <NUM> and the base <NUM> are separate parts, connected together by brazing or soldering, or more generally by an electrically conductive joint. This has the technical advantages that a stamping process for the header without the two pedestals is easier. There are a variety of manufacturing methods for the separate pedestals, such as stamping, metal drawing or extrusion. Further, as the complexity of the design is reduced by separating the manufacturing of header and pedestal, additional features can be implemented in the pedestal. One very advantageous feature is the increased freedom to design the profile of the pedestals. Specifically, the pedestals may have an L-shapes or U-shaped profile. Inter alia, profiles of this shape may be advantageous as they provide stops for the submounts which facilitates positioning thereof. Further, the protrusions of the L- or U-shaped pedestals may provide additional screening of the signal path. Also, a blend or a chamfer edge on the pedestal submount mounting side of the pedestal may be provided.

Each submount <NUM> comprises a carrier <NUM>. Without restriction to other features of the shown example, the carrier <NUM> is electrically insulating.

The pedestal submount <NUM> is preferably made of ceramic material. Suitable materials are Alumina (Al<NUM>O<NUM>) and Aluminum Nitride (ALN). If thermal conductivity is of less importance, the pedestal submount <NUM> can be also made of glass, for instance.

According to a preferred embodiment, the thickness of the pedestal submount <NUM> is between <NUM> to <NUM>. A typical thickness is <NUM>. In case of a focused electro-optical device as the electronic device to be accommodated on the header, the length of the pedestal submount may be selected based on the focal length of the lens. For example, the lens may couples the light from a DML into a glass fiber. A typical pedestal submount length is between <NUM> and <NUM>, e.g. <NUM> or <NUM>. The width of the pedestal submount <NUM> according to a further preferred embodiment is between <NUM> to <NUM>. A typical width is <NUM>.

From the manufacturing perspective, it has many advantages to have just one kind of pedestal submount <NUM>, which can be used for both pedestals <NUM>. To achieve this, the pedestal submount is symmetrical to the middle of its length. Thus, as stated above, the plane of mirror symmetry extends between the ends of the submount <NUM>. This means that the metal pattern on the top side is symmetrical to this line. However, the electrical interconnections on both ends of the pedestal submount may be different. At the base side, the RF pin can be connected by a solder joint <NUM> to the pedestal submount <NUM>. At the other end, a bond wire interconnection with ground - signal - ground configuration is connected. To accomplish this with the same metal pattern at both pedestal submount ends, the metal shapes are connected to different nets depending if the pedestal submount is used on the left or right pedestal.

The carrier <NUM> carries a structured conductor plating <NUM> with conductor traces <NUM>, <NUM>, <NUM>, <NUM>. For both submounts <NUM>, conductor trace <NUM> is electrically connected to the feedthrough pin <NUM> of an electrical feedthrough <NUM> to transmit the HF signals to the electronic device to be mounted in the gap <NUM>. As is evident from <FIG>, the ends <NUM> of the conductor traces <NUM> distal to the feedthrough pins <NUM> face each other. Further, the structuring of the conductor plating <NUM> is designed so that both submounts <NUM> including the conductor traces <NUM>, <NUM>, <NUM>, <NUM> are identical. However, the submounts <NUM> are mounted with the orientation of one submount <NUM> being flipped with respect to the other submount <NUM>. Specifically, one submount <NUM> is rotated with respect to the other about an axis perpendicular to the face of the carrier <NUM> carrying the conductor plating <NUM>. This way, the ends <NUM> of conductor traces <NUM> point toward each other, although the patterns of the conductor platings <NUM> are the same.

Further, the conductor traces <NUM>, <NUM>, <NUM> serve as grounded conductors. This way, the signal carrying conductor traces <NUM> are flanked by the grounded conductors to provide shielding and good RF-performance. Thus, specifically and without restriction to the shown specific example, at least one conductor trace of the conductor plating <NUM> may be grounded. Further, generally, a ground connection to a conductor trace may be established by at least one bond wire connection <NUM>. To provide a good connection, as also shown in <FIG>, two or more bond wire connections <NUM> may be attached in parallel for a conductor trace to provide a low impedance connection.

<FIG> shows an arrangement of two submounts <NUM> in top view onto the conductor plating <NUM>. <FIG> is also an example in accordance with the present invention, according to which the pattern of the structured conductor plating <NUM> of the submount <NUM> has a mirror symmetry. The symmetry plane <NUM> is shown in <FIG> for both submounts <NUM>. According to a further refinement of this embodiment, the submounts <NUM> have two opposite ends <NUM>, <NUM> and are mounted with one end <NUM>, <NUM> facing the base <NUM>. As also realized in the example of <FIG>, a symmetry plane <NUM> of the mirror symmetrical conductor plating <NUM> is located, or extends, respectively, between the ends <NUM>, <NUM>. The two identical submounts <NUM> are shown in their relative orientation in which they are attached to the pedestals <NUM>.

According to a further embodiment, the submounts <NUM> are assembled so that a mirror plane extends between the submounts <NUM>. Thus, the arrangement of the submounts and preferably also of the pedestals as shown in <FIG> is mirror symmetric with respect to two mirror planes, i.e. one plane extending between the ends <NUM>, <NUM> of the submounts and one plane in the middle between the submounts <NUM>, or pedestals <NUM>, respectively.

It is evident from <FIG>, that in general, the submounts <NUM> may have two opposite ends <NUM>, <NUM>, which are distinguishable with respect to the pattern of the conductor plating. Then, one of the submounts <NUM> can be attached to the pedestal with one end <NUM> facing the base <NUM> and the other submount <NUM> is attached to the pedestal with the opposite end <NUM> facing the base <NUM>. Due to this orientation and the shape of conductor trace <NUM>, its respective ends <NUM> then face each other, as is evident from <FIG>.

Further, it is advantageous, if one conductor trace of the structured conductor plating13 is U-shaped. In the example of <FIG>, this feature is realized for conductor trace <NUM>. Specifically, one of the limbs <NUM> of the U-shaped conductor trace <NUM> forming an end <NUM> facing the end <NUM> of a conductor trace <NUM> of the other submount <NUM>.

According to a refinement of this embodiment, a further conductor trace is arranged between the limbs <NUM> of the U-shaped conductor trace <NUM>. In the example of <FIG>, this is the case for the D-shaped conductor trace <NUM>.

As can be seen from the examples of <FIG>, the submounts <NUM> each have four conductor traces <NUM>, <NUM>, <NUM>, <NUM>. Conductor traces <NUM> is on both sides part of the signal line.

According to a further refinement of the embodiment with the U-shaped conductor trace, a conductor trace is arranged between a limb <NUM> of the U-shaped conductor trace <NUM> and the end <NUM>, <NUM> of the submount <NUM> proximal to the limb. In the example shown in <FIG>, this holds for conductor traces <NUM> and <NUM>.

As in the example of <FIG>, the grounded conductor traces <NUM>, <NUM>, <NUM> may be connected by bond wires. According to another alternative or additional embodiment, the submounts <NUM> comprise at least one electrical via <NUM> connecting a conductor trace <NUM>, <NUM>, <NUM>, <NUM> to the side of the carrier <NUM> opposite to the side with the structured conductor plating <NUM>. As this opposite side rests on the pedestal, a ground connection may be established from the pedestal through the via <NUM> to the conductor trace. On both submounts, D-shaped conductor trace <NUM> is connected to ground (ground pad). This may be realized by bond wire connections <NUM> as in the example of <FIG>, or by a via <NUM>, as it is shown in <FIG>. By means of the via <NUM>, the conductor trace <NUM> is grounded, as the via <NUM> establishes electrical contact to the pedestal <NUM>. If it is assumed that in <FIG> the respective lower ends <NUM>, <NUM> of the submounts <NUM> are facing the base <NUM>, then, conductor trace <NUM> of the left submount <NUM> is connected to ground and on the right-side, conductor trace <NUM> is part of the signal line. This may be achieved if a solder joint to the feedthrough pin <NUM> contacts this conductor trace additionally to conductor trace <NUM>. Vice versa, conductor trace <NUM> is on the left side part of the signal line and on the right side connected to ground. Thus, conductor traces <NUM>, <NUM> changed the nets depending on which pedestal <NUM> the submount <NUM> is mounted.

However, the via <NUM> is optional. If a via <NUM> is omitted, a thinner submount <NUM> can be used. For instance, the thickness can be reduced from <NUM> with via to a thickness of <NUM> without via. Because no laser drilling is needed, the submount <NUM> is not hard stressed. With a thinner submount <NUM>, the linewidth of the microstrip line can be reduced for the same line impedance Z<NUM>. For a line impedance Z<NUM>=<NUM> Ohm the linewidth can be reduced from <NUM> to <NUM> using a thinner submount <NUM>. The difference is <NUM>. In a compact, full packed TO header assembly, this is a great advantage.

Generally, as in the example of <FIG>, grounding of these conductor traces <NUM>, <NUM> may be achieved by bond wire connections <NUM>. Specifically, as shown, two bond wires may be used in each case. Further, the bond wires are connected to an elevated side wall or rib shaped protrusion of the pedestal <NUM>. Due to this protrusion, the pedestals <NUM> have an L-shaped cross section.

As the grounded D-shaped conductor trace <NUM> and conductor traces <NUM>, <NUM> are bracketing the signal conductor, i.e. the U-shaped conductor trace <NUM>, a coplanar waveguide structure is established at least at the end <NUM> facing towards the corresponding end <NUM> of conductor trace <NUM> on the opposite submount <NUM>.

For instance, four bond wires are used to connect shape D with the side wall of the L-shape pedestal. The bond wires are crossing the signal path shape C. Because the bond wires are exact perpendicular to the signal propagation direction no signal coupling occurs. The signal remains un-disturbed. Two technical advantages are created by the crossing bond wire interconnection:.

A multitude of bond wire connections <NUM> may be advantageous for achieving a low impedance. Moreover, the bond wire array over the microstrip line, which is established by the conductor traces, enable a smaller line width for the same line impedance as without the bond wire array. This is very important, because due to the space required by conductor trace <NUM>, the linewidth of the microstrip line becomes narrower. The bond wire array acts like a ground plane above the microstrip. In this section the RF line is a mixture of microstrip line and suspended RF line.

The effect of a ground plane above the RF signal conductor trace increases the capacitance of the RF line. Consequently, the linewidth can be reduced to maintain the same line impedance Z<NUM>. Since the RF signal conductor trace <NUM> is surrounded by air with εr= <NUM>, the line impedance does not depend strongly on the distance between RF line and bond wire array.

Further, the dense bond wire array provides a shielding over the microstrip line, or more general, over the conductor plating <NUM> forming a high frequency signal line. This shield prevents unwanted signal coupling to other components inside the header. For instance, a monitor diode or an NTC resistor (thermistor) for measurement of temperature may be influenced by electromagnetic radiation from the signal lines.

<FIG> shows the header <NUM> further assembled. Generally, a mount <NUM> for an electronic device <NUM> is arranged between the two submounts <NUM>, wherein ends <NUM> of the conductor tracings <NUM> of the submounts <NUM>, preferably ends <NUM> facing each other, are provided with bond wire connections <NUM> for connecting the electronic device <NUM>.

It is preferred to mount the electronic device <NUM> onto a further submount. This device submount <NUM> is attached to the mount <NUM>. Device submount <NUM> also has a structured conductor plating <NUM>.

Preferably, the mount <NUM> is not directly fastened to the base <NUM>. Rather, the mount <NUM> is attached to a thermoelectric cooler <NUM>, wherein the thermoelectric cooler <NUM> is coupled to the base <NUM> to dissipate heat to the base <NUM>. There is a remaining gap between the mount <NUM> and the pedestals <NUM> to avoid a thermal shortcut. However, the mount <NUM> may be electrically grounded by further bond wire connections <NUM> to the pedestals <NUM>, as shown.

The bond wire connections from the submounts <NUM> to the device submount <NUM> are advantageous to have an interconnection with very low thermal conductivity. On the other hand, bond wire interconnections have high parasitic inductances which degrade especially the high frequency signals. However, with a ground-signal-ground (G-S-G) bond wire configuration, the parasitic inductance can be significantly reduced. The ground, which may in this case also be referred to as the return path, is realized with two ground conductors framing the signal conductor. In particular, this G-S-G-configuration is realized both on the submounts <NUM> and the device submount <NUM> to achieve good RF-performance. Thus, according to a preferred embodiment, the submounts <NUM> have a structured conductor plating <NUM> which has a signal carrying conductor trace <NUM> connected to a respective feedthrough pin <NUM> and which is at least partly flanked on both edges by grounded conductors, preferably grounded conductor traces <NUM>, <NUM>, <NUM>, and wherein the signal carrying conductor trace <NUM> is connected to a signal conductor trace <NUM> on the mount <NUM> for the electronic device, wherein the signal conductor trace <NUM> on the mount <NUM> is as well flanked on both edges by grounded conductor traces <NUM>, <NUM>. Preferably, as in the shown embodiment of <FIG>, the conductor traces <NUM>, <NUM>, <NUM> are not directly arranged on the mount <NUM>, but rather placed on a device submount <NUM>.

<FIG> shows an electronic component <NUM> with a header <NUM> as described herein. An electronic component <NUM> according to this disclosure is understood as a component with a housing which accommodates an electronic device and terminals to electrically connect the electronic device within the housing. Generally, without the specific example of <FIG>, an electronic component <NUM> is provided, having a housing <NUM>. The housing <NUM> encloses an electronic device <NUM> and includes the header <NUM> according to this disclosure. The electronic device <NUM> is mounted on the header <NUM>. Further, the housing <NUM> comprises a cap <NUM>, which is attached to the header <NUM> so that a cavity <NUM> is provided, wherein the electronic device <NUM> is arranged within the cavity <NUM>.

In a preferred embodiment, the electronic device <NUM> is an optoelectronic device for sending or receiving optical signals. For this application, the housing <NUM> comprises a transparent member <NUM> to transmit the optical signals into or out of the housing <NUM>. In the exemplary embodiment of <FIG>, the transparent member <NUM> is a glass window inserted into an opening of the cap. However, other transparent members such as light guides or lenses may be used, depending on the application.

Generally and without restriction to the depicted embodiment, the optoelectronic device may be a laser diode, preferably a direct modulated laser diode (DML) which transmits the emitted laser light through the transparent member <NUM>. The DML can be operated with either differential signals or singled ended so that two signal paths are used, wherein a conductor trace on each submount <NUM> is connected to a feedthrough pin <NUM> to transmit a part of the differential signal.

<FIG> shows a pedestal <NUM> as it is also part of the embodiments of <FIG> and <FIG>. The pedestal <NUM> has two end faces <NUM>, <NUM>. The pedestal <NUM> is mounted to the base <NUM> with one of its end faces <NUM>, <NUM>. The fastening of the pedestal <NUM> to the base <NUM> is preferably done by brazing, e.g. using an AuSn-solder or AuGe solder. The profile of the pedestal <NUM> has an L-shape due to a sideward protrusion <NUM> in the form of a rib or bar. The protrusion <NUM> extends laterally along a mounting face <NUM>. The mounting face <NUM> serves to mount and fix the respective submount. Although the profile of the pedestal <NUM> is not symmetric, the pedestal <NUM> has a mirror symmetry with a mirror plane extending between the two end faces <NUM>, <NUM>. The intersection of the mirror plane with the surface of the pedestal <NUM> is shown as a hatched line <NUM>. This symmetry feature is similar to that of the submounts <NUM>. Thus, without restriction to the specific profile of the embodiment of <FIG>, two equal pedestals <NUM> are provided, each of the pedestals <NUM> carrying one of the submounts <NUM>, wherein the pedestals <NUM> on the base <NUM> have a mirror symmetry. Further, similarly to the orientation of the submounts <NUM>, one of the pedestals <NUM> is attached to the base <NUM> with one end face <NUM> and the other pedestal <NUM> is attached to the base <NUM> with the opposite end face <NUM>.

As both the pedestals and the submounts <NUM> may be mounted with respective opposite sides facing the base, it is possible to assemble the submounts <NUM> and pedestals <NUM> to obtain equal submount assemblies and to fasten the submount assemblies with respective opposite end faces to the base <NUM>.

In a preferred embodiment, the protrusion <NUM> may have the same height as the submount <NUM>, or the ratio of the height of the protrusion <NUM> to the height of the submount <NUM> is between <NUM> and <NUM>. The height of the protrusion is preferably between <NUM> and <NUM>. A typical height is about <NUM>. The width of the protrusion may be between <NUM> and <NUM>. A typical width is <NUM>. The L-shaped profile has several advantages. The ground is accessible easily from the top side of the pedestal submount. Because the protrusion is of solid metal and is as long as the pedestal submount <NUM> itself, this ground area has low inductance and is therefore preferred for RF application.

Further, the protrusion serves as an electro-magnetic shielding. The EM-Field inside the pedestal submount <NUM> can not extent over the pedestal in negative x-direction as it is possible without side wall. This way, a metal cap of the housing can be placed closer to the pedestal without EM coupling with the cap. Moreover, the protrusion serves as an alignment tool in the pedestal submount assembling process. The pedestal submount can be assembled more precisely.

Another realization is of course a flat pedestal <NUM>. In other words, in this case, the side of the pedestal <NUM> with the mounting face <NUM> is plane. In this case, the bond wires <NUM> must go down to the pedestal surface to get in contact with ground. This makes the bond wire longer. This may not be advantageous for very high frequency applications. On the other hand, this design is simple and also allows to use two equal pedestals. This embodiment is particularly suited for applications with lower signal rates to save costs.

<FIG> shows an alternative embodiment of a pedestal <NUM>. In difference to the embodiment of <FIG>, this embodiment has a U-shaped profile with protrusions <NUM> extending along opposite sides of the mounting face <NUM>. According to one embodiment, which is also realized by the U-shaped profile, the pedestal <NUM> may generally have a mirror symmetric profile. The mirror plane in this case extents parallel to the protrusion through the center of the profile. The intersections <NUM> of both symmetry planes are shown in <FIG>. In this case with a double mirror symmetry, the pedestals <NUM> can be attached to the base <NUM> with either of the end faces <NUM>, <NUM> without altering the design.

As also in the example of <FIG>, these protrusions <NUM> may serve to provide a ground-signal-ground configuration as well. Specifically, in the embodiment with the L-shaped profile of the pedestal <NUM>, the protrusion <NUM> is a grounded conductor which flanks the side of the C-shaped conductor trace <NUM> which is opposite to the side facing the d-shaped conductor trace <NUM>. In the embodiment of <FIG>, the signal conductor trace may be flanked on both sides by the protrusions <NUM>, which are electrically grounded. Thus, a D-shaped conductor trace <NUM> as in the example of <FIG> may be omitted.

A submount <NUM> which fits to a U-shaped pedestal <NUM> is shown in <FIG>. As the embodiment with the C-shaped conductor trace, a symmetry plane <NUM> extends between the ends <NUM>, <NUM>.

<FIG> shows the assembly of the pedestal <NUM> of <FIG> and the submount <NUM> of <FIG>. As the example of the submount <NUM> of <FIG> has no further mirror symmetry plane in direction parallel to the side edges <NUM>, <NUM>, the assembly lacks of a second symmetry plane defined by the symmetry of the profile of the pedestal <NUM>. However, similar to the L-shaped pedestal <NUM>, the assembly may be preassembled and mounted to the base <NUM> with the respective end faces <NUM>, <NUM>. Similarly, so that the assemblies are equal, but arranged mirror symmetrical on the base <NUM>. Thus, as for the embodiment with the L-shaped pedestal, the submounts <NUM> are equal and have two opposite ends <NUM>, <NUM>, wherein one of the submounts <NUM> is attached to the pedestal <NUM> with one end <NUM> facing the base <NUM> and the other submount <NUM> is attached to the pedestal with the opposite end <NUM> facing the base <NUM>.

<FIG> shows an embodiment of a pedestal <NUM> having a L-shaped profile at end <NUM> and a U-shaped profile at the opposite end <NUM>. The different profiles result from one of the protrusions being shorter than the other protrusion <NUM>. Due to this design, the mounting face <NUM> is L-shaped. Obviously, this embodiment lacks of a mirror symmetry. However, the L-shaped submount <NUM> according to <FIG>, which fits to the L-shaped mounting face <NUM> of the pedestal of <FIG>, may still have a mirror symmetry. This allows to fabricate left and right submounts <NUM> as equal parts. Specifically, on both opposite faces of the carrier <NUM> a structured conductive plating <NUM> may be arranged, wherein the conductive platings <NUM> have a mirror symmetry with a symmetry plane extending centered between the sides of the submount <NUM>, or the carrier <NUM>, respectively. Of course, this feature is not restricted to the particular L-shaped design of <FIG>. Rather, a front- and backside-plating may be present at all embodiments of submounts <NUM> disclosed herein. <FIG> is a top view onto one of the sides of the carrier <NUM>. Accordingly, the plane of mirror symmetry is parallel to the side shown in <FIG> and thus extends parallel to the plane of projection of <FIG>. Thus, according to one embodiment, a header <NUM> is provided, further comprising at least one pedestal <NUM> connected to the base <NUM>, and two equal submounts <NUM>, each submount <NUM> comprising a carrier <NUM> with structured conductor platings <NUM> on two opposite sides, wherein a plane of mirror symmetry extends parallel to and between the two opposite sides.

According to a further advantageous embodiment, the end <NUM> of the conductor trace <NUM> which is distal to the end connected to the feedthrough pin <NUM> is widened. Widening is understood as a broadening of the width of the conductor trace towards its end distal to the feedthrough pin <NUM>. This embodiment is also realized and visible in the examples of <FIG> and <FIG>. Generally, the widening may be achieved by providing a projecting edge <NUM> at the end <NUM> distal to the end connected to the feedthrough pin. Preferably, as also in the depicted embodiments, only one side of the end of the conductor trace <NUM> connected to the feedthrough pin is widened. Accordingly, there is only one projecting edge at the end <NUM> of the conductor trace <NUM>. This is preferred in case of space limitations.

<FIG> is a top view onto the header <NUM>. The mount <NUM> and the thermoelectric cooler are not shown for the sake of simplicity. The conductor pattern of the device submount <NUM> has a ground-signal-ground configuration similar to the conductor pattern <NUM> on the submounts <NUM>. Specifically, the signal conductor traces <NUM> on the submounts <NUM> are connected to signal conductor traces <NUM> on the device submount <NUM> and the grounded conductor traces <NUM>, <NUM>, <NUM> on the submounts <NUM> are connected to the ground conductor traces <NUM>, <NUM> on the device submount <NUM>. The connections are established by bond wire connections <NUM>.

As described with respect to <FIG>, it is advantageous to widen the end <NUM> of the signal carrying conductor trace <NUM> on the pedestal <NUM>. Further, also the signal conductor traces <NUM> on the device submount <NUM> are widened at their respective ends <NUM> with which they are connected to the conductor traces <NUM> by the bond wire connections <NUM>. The widening of the ends <NUM> and <NUM> increases the line capacitance. This design is advantageous because the addition of capacitance lowers the effective impedance of the bond wire connections <NUM>. Specifically, the widening of the signal carrying conductor traces <NUM>, <NUM> can at least partly compensate an increase of the line impedance induced by the bond wire connections. Thus, in addition to the feature that the end <NUM> of the conductor trace <NUM> of each submount <NUM> which is distal to the end connected to the feedthrough pin <NUM> is widened, both ends of the signal conductor traces on submounts <NUM>, <NUM> may be widened. Accordingly, a header <NUM> with a device submount <NUM> for mounting the electronic device <NUM> is provided, wherein a conductor trace <NUM> on the submount <NUM> is connected to a feedthrough pin <NUM>, and wherein this conductor trace <NUM> is connected to a signal conductor trace <NUM> on the device submount <NUM>, wherein the connection is established by at least one bond wire connection <NUM> bridging a gap <NUM> between the submount <NUM> and the device submount <NUM>, and wherein the ends <NUM>, <NUM> of the conductor traces <NUM>, <NUM> which are connected by the bond wire connection <NUM> are widened.

<FIG> shows a section of the header <NUM> with one of the pedestals <NUM> and represents a variant of the embodiment of <FIG>. Specifically, this variant concerns the electrical connection of the feedthrough pin <NUM> to the signal conductor trace <NUM>. In the embodiment of <FIG>, the feedthrough pin is a cylindrical or wire like member. However, according to one embodiment, the feedthrough pin <NUM> includes a head <NUM>, wherein the head <NUM> is formed and arranged or positioned so as to reduce the distance of the pin <NUM> to the conductor plating <NUM> of the submount <NUM>. Reducing the distance is advantageous to reduce the insertion loss at the junction between pin <NUM> and submount <NUM>. According to a refinement, which is realized in the shown example, the head has a shape resembling that of a golf club. The shape of the pin <NUM> may also described as having a shaft <NUM> and a head <NUM> with a wing <NUM> that extends transverse to the longitudinal direction of the pin <NUM> so that the end of the wing <NUM> juts over the circumferential surface of the shaft <NUM>. In particular, the wing <NUM> may then be oriented so that the distance to the conductive plating <NUM> on the submount <NUM> is reduced. Further, the head <NUM> can be used to bridge the conductor trace <NUM> nearest to the base <NUM>. Then, this conductor trace <NUM> may be grounded, e.g. as shown using a bond wire connection <NUM> to the projection <NUM> of the pedestal <NUM>.

<FIG> is a cross sectional view of a part of the header <NUM> and shows an example of an alternative embodiment of a feedthrough <NUM>. Generally, as for all embodiments disclosed herein, the feedthrough <NUM> may include a glass insulation <NUM> to fix the feedthrough pin <NUM> within the opening or eyelet <NUM>. As in the example of <FIG>, the feedthrough pin <NUM> has a head <NUM>. Further, <FIG> is an example of an embodiment with at least one of the following features:.

Feature (iv) in other words means that the surface of the submount <NUM> with the structured conductive plating <NUM> is at a height that it crosses the eyelet <NUM>, or even the head <NUM> if viewed along the shaft <NUM> of the pin <NUM>. Due to this configuration, or the configuration according to feature (ii), the conductive plating <NUM> can be positioned very close to the head <NUM>, thereby reducing insertion losses. The recessed glass insulation <NUM> further makes sure that no insulation material can protrude out of the eyelet <NUM> due to tolerances in the fabrication. Protruding glass portions could prohibit placing the submount <NUM> over the eyelet <NUM>. Further, the recessed glass together with the heads increased diameter result in an improved impedance matching.

Claim 1:
A header (<NUM>) for an electronic component, comprising a base (<NUM>) with at least two electrical feedthroughs (<NUM>), each comprising a feedthrough pin (<NUM>) extending through the base (<NUM>) and being electrically isolated to the base (<NUM>) within the feedthrough (<NUM>), the header (<NUM>) further comprising two pedestals (<NUM>) connected to the base (<NUM>), and two submounts (<NUM>), each submount (<NUM>) comprising a carrier (<NUM>) with a structured conductor plating (<NUM>), with the conductor plating (<NUM>) comprising at least two conductor traces (<NUM>, <NUM>, <NUM>, <NUM>), with one of the conductor traces (<NUM>, <NUM>, <NUM>, <NUM>) of each submount (<NUM>) being electrically connected to one of the feedthrough pins (<NUM>), each of the pedestals (<NUM>) carrying one of the submounts (<NUM>), the pedestals (<NUM>) being connected to the base (<NUM>) with a gap in between, the gap (<NUM>) serving to accommodate an assembly for carrying an electronic device, the conductor plating on the submounts (<NUM>) being symmetrical such that, when mounted to the respective pedestals (<NUM>), ends (<NUM>) of the conductor traces (<NUM>, <NUM>, <NUM>, <NUM>) that are connected to the feedthrough pins (<NUM>) and that are distal to the feedthrough pins (<NUM>) face each other such that electrical connection to the electronic component from opposite directions is enabled, characterized in that the pattern of the structured conductor plating (<NUM>) of the submount (<NUM>) has a mirror symmetry, the submounts (<NUM>) being identical and mounted in different orientations on respective ones on the provided pedestals (<NUM>).