TO package with feedthrough made of glass
阅读说明：本技术 具有由玻璃制成的馈通件的to封装件 (TO package with feedthrough made of glass ) 是由 R·海特乐 A·奥尤都马萨克 K·谭 K·德勒格米勒 于 2019-08-27 设计创作，主要内容包括：一种TO封装件(1),其包括具有用于光电子元件的安装区域的底座(2),其中,所述底座(2)包括至少一个布置在馈通件(9)中的用于连接光电子元件的信号引脚(7、7a、7b),其中所述馈通件(9)用包含玻璃和/或玻璃陶瓷的绝缘材料(18、18a、18b)填充,并且其中,在至少一侧上,所述馈通件(9)未完全用包含玻璃和/或玻璃陶瓷的绝缘材料(18、18a、18b)填充,其特征在于,在绝缘材料(18、18a、18b)凹入的区域形成了至少部分地围绕信号引脚(7、7a、7b)的空腔(25),并且所述信号引脚(7、7a、7b)在该区域具有加厚部(19)。(TO package (1) comprising a base (2) with a mounting area for an optoelectronic component, wherein the base (2) comprises at least one signal pin (7, 7a, 7b) arranged in a feedthrough (9) for connecting an optoelectronic component, wherein the feed-through (9) is filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic, and wherein, on at least one side, the feed-through (9) is not completely filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic, characterized in that a cavity (25) is formed at least partially around the signal pin (7, 7a, 7b) in the region where the insulating material (18, 18a, 18b) is recessed, and the signal pin (7, 7a, 7b) has a thickened portion (19) in this region.)
1. A TO package (1) comprising a base (2) with a mounting area for an optoelectronic component, wherein the base (2) comprises at least one signal pin (7, 7a, 7b) arranged in a feedthrough (9) for connecting the optoelectronic component, wherein the feedthrough (9) is filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic, and wherein on at least one side the feedthrough (9) is not completely filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic, characterized in that:
a cavity (25) is formed at least partially around the signal pin (7, 7a, 7b) in the region in which the insulating material (18, 18a, 18b) is recessed, and the signal pin (7, 7a, 7b) has a thickening (19) in this region.
2. The TO package according TO the preceding claim, characterized in that 30 TO 95%, preferably 50 TO 90% and particularly preferably 60 TO 80% of the volume of the feedthrough (9) is filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic.
3. The TO package according TO one of the preceding claims, characterized in that the areas where no insulating material (18, 18a, 18b) comprising glass and/or glass ceramic is present are filled with a plastic, in particular with an epoxy resin, preferably the plastic has a dielectric constant ∈r(at 18 ℃ and 50 Hz), which corresponds to a dielectric constant of +/-1.0 of the insulating material comprising glass and/or glass-ceramic.
4. The TO package of claim 3, wherein the plastic material has a dielectric constant ε of 4.0+/-2.5, preferably +/-1.5r(at 18 ℃ C. and 50 Hz).
5. The TO package according TO any of the preceding claims, characterized in that the feedthrough (9) is filled with an insulating material (18, 18a, 18b) comprising glass and/or glass-ceramic, the insulating material (18, 18a, 18b) having a dielectric constant ∈ of less than 5.0, preferably less than 4.0r(at 18 ℃ C. and 50 Hz).
6. The TO package according TO any of the preceding claims, characterized in that the insulating material (18, 18a, 18b) is made of or comprises glass made of porous glass and/or porous glass-ceramic, preferably the thickened portion (19) has a diameter of 1.2 TO 3.0 times, preferably 1.5 TO 2.5 times the diameter of the signal pin (7, 7a, 7b) adjacent TO the insulating material comprising glass and/or glass-ceramic.
7. The TO package according TO claim 6, characterized in that the thickening (19) has a length l of 0.02 TO 0.2mm, preferably 0.05 TO 0.1mmv。
8. The TO package according TO any of the preceding claims, characterized in that the feedthrough (9) has a region (26) of increased diameter on at least one side, preferably the region (26) of increased diameter is partially filled with an insulating material (18, 18a, 18b) comprising glass and/or glass ceramic.
9. The TO package according TO claim 8, characterized in that the diameter of the increased diameter region (26) is at least 1.2 times the diameter of the adjacent feedthrough (9) and/or has a length of 0.05 TO 0.5mm, preferably 0.1 TO 0.3 mm.
10. The TO package according TO any of the preceding claims, characterized in that a printed circuit board (12) is mounted substantially coaxially on the signal pins (7, 7a, 7b), wherein preferably the printed circuit board (12) is mechanically and electrically connected TO the base (2) by means of at least one metal block (13) adjoining the feedthrough (9) TO provide a ground connection.
11. The TO package according TO claim 10, characterized in that the printed circuit board (12) is designed as a flexible printed circuit board and/or the printed circuit board (12) is provided with a stiffener (11) under the metal block (13) and/or the TO package (1) comprises at least two, in particular exactly two, signal pins (7, 7a, 7b) each arranged in a feedthrough.
12. The TO package according TO claim 10 or 11, characterized in that the printed circuit board (12) is constructed thickly adjacent TO the bottom side of the TO package, in particular the printed circuit board (12) has a thickened multi-layer area.
13. Device for data transmission with a data transmission rate of at least 100Gbit/s per wavelength, comprising at least one TO package (1) according TO at least one of claims 1 TO 12.
Technical Field
The present invention relates TO a TO package (TO-TO package) which should be able TO achieve a high data transfer rate.
Background
TO packages with glass-sealed signal pins are known. Such TO packages typically include a base made of metal through which at least one signal pin is guided, the signal pin being located in a glass feedthrough. The optoelectronic component, in particular a laser diode, can be contacted via a signal pin. A hermetically sealed package with high temperature resistance can be provided in a simple manner by means of a glass feed-through, in particular a molten glass feed-through.
At present, it is common in the 100G Internet standard that the data transmission rate per channel is 25 Gbit/s. To reach the next internet standard 400G, the data transmission rate must be approximately doubled to reach about 100Gbit/s per wavelength.
This requires doubling of both the bandwidth and the transmission frequency.
The area of the glass feed-through of the TO package is problematic because, due TO the insulation made of glass, which has a different dielectric constant than air, there is always a sudden change in the impedance of the signal line. Such an abrupt impedance change can be compensated, for example, by an excess of the signal pin on the bottom side of the package.
Furthermore, there is a problem that the fillers used, which are made of glass, are affected by volume fluctuations. Due to the different filling volumes, a modified meniscus is formed, in particular at the end of the glass feedthrough. This may negatively affect the desired impedance of the signal path. It is known from practice to push the meniscus back by means of a carbon sleeve. But this is very expensive.
Disclosure of Invention
The present invention is based on the object of providing a TO package which achieves high data rates and in which fluctuations in the filling volume of the insulating material made of glass or glass ceramic influence the impedance curve of the signal path of the TO package as little as possible, and the use of such a TO package.
The object of the invention has been achieved by a TO package according TO claim 1.
Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description and the drawings.
The TO package includes a base having a mounting area for an optoelectronic component. Provision is made in particular for the encapsulation to comprise a base made of metal, in particular of metal provided with a coating.
The mounting area is located inside the package. The package may be closed with a lid that includes a window through which electromagnetic radiation may pass.
The base comprises at least one signal pin arranged in the feedthrough for connecting the optoelectronic component. The optoelectronic component is designed in particular as a laser diode. The at least one signal pin is used for controlling or modulating the optoelectronic element for data transmission. The invention particularly relates TO a TO package with an emitting diode.
It will be appreciated that the optoelectronic component may also include other electrical feedthroughs, particularly those used, for example, to power the component, to control other components (e.g., monitor diodes or thermoelectric coolers).
These feed-throughs are less problematic in the design of the signal path, since these other feed-throughs are either not used at all for data transmission or, for example in the case of a monitor diode, are used for a smaller data transmission rate than the signal pin relative to the optoelectronic component.
The feedthrough is filled with an insulating material comprising, in particular made of, glass and/or glass ceramic, in which the signal pin is embedded. In particular, the insulating material is formed as a filler or pressure glass feedthrough in which the signal pins are arranged.
According to the invention, on at least one side, the feed-through is not completely filled with an insulating material made of glass and/or glass ceramic.
Thus, on at least one side of the feedthrough there is a region in which the insulating material made of glass and/or comprising glass ceramic is recessed, i.e. the insulating material does not reach all the way to the end of the feedthrough at the top or bottom face of the base.
The invention therefore provides that the volume of the feed-through is not completely filled with an insulating material made of glass and/or containing glass ceramic, but that a region is provided on at least one side in which the feed-through is not filled with an insulating material made of glass and/or containing glass ceramic below the top or bottom side of the base.
Fluctuations in the volume of the insulating material made of glass in the feedthrough can thus be compensated for. Since the meniscus is at least partially arranged in the feedthrough, the formation of a meniscus on the top or bottom surface of the mount can be largely avoided.
In particular, it is provided that 30 to 95%, preferably 50 to 90%, particularly preferably 60 to 80% of the volume of the feedthrough is filled with an insulating material made of glass and/or containing a glass ceramic.
According to one embodiment of the invention, the area in which the insulating material made of glass and/or containing glass-ceramic is recessed may form a cavity around the signal pin. The cavity may in particular be embodied as a recess in the base, the bottom of which is formed by an insulating material.
This has the effect that the electromagnetic field is transferred along an improved extended, in particular gradually changing, impedance curve from the feedthrough TO the signal pin leading TO the optoelectronic component in the TO package and/or TO the signal path. This transfer takes place more softly through the cavity, which reduces the attenuation.
According to a further embodiment of the invention, regions in which no insulating material made of glass and/or containing glass ceramic is present are filled with plastic, in particular with epoxy resin.
Filling with another insulating material made of plastic has the advantage that the thus recessed area is not surrounded by air. Air has a dielectric constant ε of about 1rAnd thus the impedance changes abruptly.
This abrupt change can be reduced by using a filler made of plastic.
In processing technology, in contrast to melting glass, it is easier here to fill the regions which are not filled with insulating material made of glass, without causing a meniscus to form.
For example, plastics can be used which are cured by heat or by means of light, in particular UV light.
In particular, a plastic with a dielectric constant adapted to glass is used. In particular, a dielectric constant εrPlastic (at 18 ℃ and 50 Hz), which corresponds to the dielectric constant of an insulating material made of glass +/-1.0.
According to one embodiment of the invention, the plastic material has a dielectric constant ε of 4.0+/-2.5, preferably 4.0+/-1.5r(at 18 ℃ C. and 50 Hz).
According to a preferred embodiment of the invention, the feedthrough is filled with an insulating material having a low dielectric constant, made of glass and/or comprising a glass ceramic. In particular, it is provided that glass and/or glass ceramic is used, which has a dielectric constant ε of less than 5.0, preferably less than 4.0r(at 18 ℃ C. and 50 Hz).
It has been found that not only the insertion loss but also the return loss can be improved thereby.
For this purpose, insulating materials made of porous glass can be used in particular. In this case, glass is in particular provided which has a closed-cell gas enclosure (gas inclusion). Preferably, the glass has a closed porosity of at least 5%, particularly preferably greater than 10%. A hermetic seal can be achieved despite the closed cell design. Glass-ceramics having these properties are also possible. In particular, a glass ceramic in which pores are formed by crystallization may be used.
According to another embodiment, glass or glass-ceramic is used, which has a higher dielectric constant, in particular a dielectric constant epsilonr between 5.0 and 8, preferably between 6.5 and 7. Such glasses are particularly suitable for use in pressure glass feedthroughs, i.e., feedthroughs in which the glass is under thermally induced mechanical compressive stress.
The recessed area, which is at the bottom, i.e. the side on the outside of the feedthrough, is preferably filled with plastic.
In a further embodiment of the invention, the signal pin has a thickening in the region of the feedthrough, wherein no insulating material made of glass and/or glass ceramic is present. The regions without insulating material made of glass and/or glass ceramic may in particular be present as recesses in the base. The bottom of the recess is formed by the surface of the insulating material. The thickened portion need not be completely within the recess. It may also partly protrude into the insulating material.
The thickened portion can be configured, for example, as a collar or as a disk (Scheibe).
The thickening is preferably located completely in the feedthrough.
In particular, the diameter of the thickened portion is 1.2 to 3.0 times, preferably 1.5 to 2.0 times, the diameter of the signal pin adjacent to the insulating material made of glass.
The thickened portion or collar is arranged in particular on the inner side.
Due to the thickening, the ratio of the diameter of the feedthrough to the diameter of the pin changes in the region not filled with insulating material.
In this way, abrupt changes in impedance due to the changing dielectric constant surrounding the signal pin in the regions not filled with glass and/or glass ceramic can be further reduced.
In a preferred embodiment of the invention, the thickened portion has a length l of 0.02 to 0.2mm, preferably 0.05 to 0.1mmv。
In another embodiment of the invention, the feedthrough has a region of increased diameter on at least one side of the feedthrough.
In particular, it is provided that the region of increased diameter is partially filled with an insulating material made of glass.
In particular, the diameter of the region of increased diameter is at least 1.2 times the diameter of the adjacent feedthrough. Preferably, the region of increased diameter has a length of 0.05 to 0.5mm, particularly preferably 0.1 to 0.3 mm.
The region of increased diameter also allows the impedance curve of the signal line to be matched. Further, the region of increased diameter serves as a volume reservoir (volumeenreservoir) for glass volume fluctuation.
Preferably, the region of increased diameter is partially filled with glass and/or glass ceramic. The meniscus that may be formed preferably does not protrude beyond the top or bottom surface of the base.
In the regions not filled with glass or glass ceramic, the region of increased diameter is preferably configured as a cavity or filled with a material having a lower dielectric constant than the glass of the insulating material.
Therefore, abrupt impedance changes can be reduced by partially balancing inductance and capacitance. The insulating material partially present in the region of increased diameter leads to a non-matching disk for the impedance, which at least partially compensates for the abrupt change in impedance caused by the adjacent, unfilled region of the feedthrough.
In one development of the invention, the TO package is connected TO a printed circuit board, which is mounted substantially coaxially on the signal pins.
It has been found that the impedance curve can also be improved by a coaxially arranged printed circuit board.
Preferably, the printed circuit board is mechanically and electrically connected to the base by means of at least one metal block abutting said feedthrough to provide a ground connection.
The grounding of the TO package is thus not realized by grounding pins, but by metal blocks, which form an angle, in particular a right angle, and which thereby connect the printed circuit board and the bottom side of the package TO one another.
The metal block is adjacent to the signal pin(s) and thus shields the signal pin(s). The metal block is designed in particular as a plate. In a preferred embodiment of the invention, the metal block is designed as a bridge, which spans at least one signal pin.
The metal block is preferably designed as a solid metal part, for example made of copper. However, in another embodiment of the invention, it is also conceivable to coat the non-conductive material with a metal.
Another advantage of the metal block for the ground connection and at the same time for the mechanical connection is that the soldering of the pins, in particular of the signal pins, and the soldering of the ground connection are separate from each other.
In particular, if the TO package has two signal pins, they may be attached TO the printed circuit board first. Since only the two signal pins are attached, there is a higher tolerance for positional tolerance than if the ground pins were soldered simultaneously.
In a next step, a mechanically stable connection may then be provided by grounding.
The printed circuit board is preferably designed as a flexible printed circuit board. It can be bent, in particular, by 90 ° in order to be inserted, for example, into a plate.
Furthermore, according to a further development of the invention, the printed circuit board can be provided with a reinforcement under the metal block.
The reinforcement stabilizes the printed circuit board in the region of the metal block and furthermore enables a simple attachment of the metal block to the printed circuit board, in particular by soldering.
According TO one embodiment of the invention, the printed circuit board may be thickly configured adjacent TO the bottom surface of the TO package.
In particular, it is provided that the thickened region of the printed circuit board is designed as a multilayer, in particular rigid, printed circuit board, which is integrated into a flexible printed circuit board.
The thickened multi-layer region can provide further connections, for example for the connection of a monitor diode.
Furthermore, the thickened region may simultaneously form the reinforcement described above.
Drawings
The object of the invention will be explained in more detail below with reference to embodiments with the aid of fig. 1 to 21.
Fig. 1 TO 4 are perspective views (without a cover) of an embodiment of a TO package according TO the present invention.
Fig. 5 is a perspective view of the inside of the package without the substrate (Submount).
Fig. 6 is a detail view, partly broken away, and in which details of the printed circuit board are shown.
Fig. 7 is a perspective view of the bottom surface of the base.
Fig. 8 is a detail view of a cross section through a feedthrough of a mount.
The graphs according TO fig. 9 and 10 show the return loss and insertion loss of the packages shown in fig. 1 TO 8 compared TO packages known in the prior art.
Fig. 11 is a cross-sectional view of a feedthrough having an increased diameter on one side edge.
Fig. 12 is a cross-sectional view of a feedthrough with a signal pin having a thickened portion on one side.
Fig. 13 is a detailed view of the signal pin.
The graph according TO fig. 14 shows the return loss of the TO package according TO the present invention in case of using different types of glass.
The graph according TO fig. 15 shows the return loss of a TO package according TO the invention, in which the feedthrough is partially filled with glass and partially with plastic, in the case of different types of glass and plastic.
Fig. 16 is a cross-sectional view of an embodiment of a mount in the region of a signal pin and a feedthrough of a substrate for an optoelectronic component.
Fig. 17 is a perspective view of a TO package with a lid.
Fig. 18 shows a TO package equipped with an optoelectronic element.
Fig. 19 to 21 show schematic cross-sectional views of a base with a feedthrough.
Detailed Description
Fig. 1 is a perspective view of a TO package 1 according TO the present invention.
The TO package 1 includes a base 2. In this embodiment, the base 2 has a circular cross-section. Preferably, the base 2 is made of metal, in particular of metal with a coating, for example a coating consisting of gold.
In this embodiment, the base 2 comprises two signal pins 7a, 7b, which are guided through the base 2 via feedthroughs 9.
The base 2 includes a top surface 21 that forms the inner wall of the TO package 1 that is then hermetically sealed after the lid is attached.
The signal pins 7a, 7b are connected with the conductive tracks 6a, 6b by means of solder 8.
The optoelectronic component, in particular a laser diode (not shown), is contacted via the electrically conductive tracks 6a, 6 b. This embodiment of the invention is therefore provided for a laser diode with two signal conductor paths.
The conductive tracks 6a, 6b are located on a substrate 5, which in turn is applied on a support 4, which protrudes from the top surface 21 of the base 2.
Preferably, the seat 4 is formed integrally with the base. The base 2 and the support 4 may in particular be formed as an integral stamping.
In this embodiment, the support 4 has a circular segment-shaped cross section. However, it is also conceivable to design the support 4 differently, for example with a rectangular cross section.
The substrate 5 is oriented coaxially with the signal pins 7a, 7b, so that the bottom face of the laser diode is oriented perpendicularly to the top face 21 of the submount 2 in the assembled state.
The substrate 5 is preferably made of ceramic. For example, alumina ceramics may be used. Preferably, the substrate 5 is made of aluminum nitrite ceramic. The aluminum nitrite ceramic has high thermal conductivity.
The TO package 1 in this embodiment comprises at least one further pin 10 in addition TO the signal pins 7a, 7 b. This pin can be used, for example, for connecting a monitor diode. It should be understood that other embodiments of the present invention may also include other pins, for example, for controlling a thermoelectric cooler (not shown).
Fig. 2 is another perspective view of the TO package 1.
It can be seen in particular that the signal pins 7a, 7b and the pin 10 protrude perpendicularly from the top surface of the base 2.
The same applies to the holder 4 with the base plate 5.
The signal pins 7a, 7b merge coaxially into the conductive tracks 6a, 6 b. The conductive tracks 6a and 6b on the substrate 5 converge towards one another, so that the optoelectronic component can be placed directly on the conductive track 6a and can be brought into contact with the other conductive track 6b by means of a bonding wire.
Fig. 3 is another perspective view of the TO package 1 showing the bottom surface 14 of the TO package.
The signal pins 7a, 7b are visible protruding from the bottom surface 14.
The signal pins 7a, 7b are connected to the printed circuit board 12.
In this view, the printed circuit board 12 is only partially shown. The printed circuit board 12 can be designed, for example, as a flexible printed circuit board and is connected at an angle to an electronics module (not shown).
The printed circuit board 12 is provided with a reinforcement 11 on its bottom surface. The reinforcement 11 is preferably made of a dielectric material, for example plastic or ceramic.
By means of the reinforcement 11 it is achieved that, for example, the flexible printed circuit board 12 is rigid and stable even adjacent to the bottom surface 14 of the base 2.
In order to provide a stable mechanical connection as well as a ground connection between the base 2 and the printed circuit board 12, a metal block 13 is provided which is connected, in particular soldered, on the one hand to the printed circuit board 12 and on the other hand to the bottom surface 14 of the base 2.
The metal block 13 forms an angle which enables a coaxial arrangement of the printed circuit board 12 with respect to the signal pins 7a, 7 b.
In this embodiment, the metal block 13 is designed as a bridge, which spans the signal pins 7a, 7b in an arc 15a, 15b, respectively.
The signal pins 7a, 7b preferably do not protrude beyond the metal block 13.
The metal block 13 can project in the region of the arcs 15a, 15b all the way into the region of the feedthrough (9 in fig. 1 and 8).
The signal pins 7a, 7b are also shielded outside the feedthrough by means of a metal block 13.
The metal block 13 is preferably of plate-like construction.
By means of the metal block 13, a ground connection can be realized not only between the signal pins 7a, 7b but also beside the signal pins 7a, 7 b.
Preferably, the metal block 13 has a thickness d of more than 0.1mm, particularly preferably more than 0.5mm and/or less than 5mm, particularly preferably less than 2 mm.
The metal block 13 may extend over a majority of the diameter of the base 2 over the width, in particular over at least 20%, preferably at least 50%, of the diameter of the base 2.
The height h of the metal block 13 preferably corresponds to at least 1.5 times the diameter of the feedthrough.
In addition to the stable mechanical connection of the printed circuit board 12, the metal block 13 has the advantage at the same time that the attachment of the signal pins 7a, 7b on the printed circuit board 12 is separated from the provision of a ground connection.
Thus, for example, the signal pins 7a, 7b can be soldered to the printed circuit board 12.
Since at this point in time there is no mechanical connection to the printed circuit board 12, shape and position tolerances can be compensated well.
In a next step, the metal block 13 may be connected with the base 2 and/or the printed circuit board 12 to form a ground connection.
It can furthermore be seen that on the opposite side of the printed circuit board 12 to the signal pins 7a, 7b, further pins 10 are present. This further pin 10 is also located in the feedthrough and is used in this embodiment for connecting a monitor diode.
The further pin 10 is connected to a stiffener 11 which at the same time serves as a printed circuit board.
Fig. 4 is another perspective view of the bottom surface 14 of the TO package.
It can be seen that the signal pins 7a, 7b are embedded in an insulating material 18a, 18b made of glass.
The signal pins 7a, 7b protrude from the bottom surface 14 through the feed-throughs thus formed.
The signal pins 7a, 7b are coaxially connected with the signal conductive traces 17a, 17b of the printed circuit board 12.
Between the signal conductive traces 17a, 17b, a ground conductive trace 16b is located on the printed circuit board 12. The ground conductive traces 16a and 16c adjoin the signal conductive traces 17a, 17b on both sides. Thus, the signal conductive traces 17a, 17b are shielded on both sides.
Fig. 5 is a view of the inside of a TO package with the standoffs and substrate hidden.
In this view, it can be seen that the signal pins 7a, 7b, which are embedded from the inside in the insulating material 18a, 18b made of glass, each have a thickened portion 19a, 19 b. In the region of these collar-like thickenings 19a, 19b, regions are formed which are free of insulating material made of glass. The resulting sudden change in impedance is at least partially compensated for by the thickened portions 19a, 19 b.
Fig. 6 is a perspective view in section, in which the printed circuit board 12 can be seen as a multi-layer printed circuit board.
On the top surface, the printed circuit board 12 includes signal conductive traces 17a, 17b and ground conductive traces 16a to 16c shown in fig. 4.
The ground conductive traces 16a-16 c are connected by plated through holes 20 to an underlying ground conductive trace 16d that also extends under, and thus shields, the signal conductive traces 17a, 17b shown in fig. 4.
The multilayer printed circuit board designed in this way is placed on the stiffener 11, and the ground conductive traces 16a to 16c are soldered to the metal block 13
The reinforcement 11 is thus simultaneously formed as a thickened region which forms a multilayer printed circuit board through which plated through holes are provided from the bottom side up to the printed circuit board 12.
The multilayer printed circuit board formed by the thickened region or the reinforcement 11 is designed as a rigid printed circuit board, whereas the printed circuit board 12 is preferably designed as a single-layer flexible printed circuit board.
On the underside of the reinforcement 11, additional pins (10 in fig. 3) can therefore be connected for connecting, for example, a monitor diode.
Fig. 7 is another perspective view of the bottom surface of the TO package.
The metal block is hidden in this view. It can clearly be seen that the signal pins 7a, 7b protruding from the bottom surface 14 are connected to the signal conductive tracks 17a, 17b of the printed circuit board 12 by means of solder.
Fig. 8 is a detail view of a cross section in the region of the feed-through 9.
In the feed-through 9 the signal pins 7 are arranged in an insulating material 18 made of glass.
For this purpose, the base 2 comprises a through hole 23.
However, the feedthrough 9 or the through-opening 23 is only partially filled with an insulating material 18 made of glass and/or glass ceramic, so that, adjacent to the bottom side 14 as well as to the top side 21, there is an area 22 which is free of the insulating material 18, surrounds the signal pin 7 and is not filled with an insulating material made of glass and/or glass ceramic.
On the inside, a cavity 25 is present in this unfilled region 22. In the region of the cavity 25, a thickened portion 19 of the signal pin 7 is present.
By the thickened portion 19 of the signal pin 7, abrupt changes in impedance due to changes in dielectric constant are reduced.
On the outside, the unfilled region 22 is filled with a filler 24 made of plastic.
The dielectric constant of the filler 24 made of plastic is preferably matched to the dielectric constant of the insulating material 18 made of glass used.
In particular, the plastic has a dielectric constant ε of 4.0+/-2.5, particularly preferably +/-1.5r。
As insulating material 18 made of glass or glass ceramic, it is preferred to use a material having a dielectric constant ε of less than 5.0, preferably less than 4.0rGlass and/or glass-ceramic (at 18 ℃ and 50 Hz).
In particular, porous glasses, in particular glasses having a closed porosity of more than 30%, and/or glass ceramics having these properties can be used.
The diameter of the signal pin (outside the region of the thickened portion 19) is preferably 0.1 to 0.5mm, particularly preferably 0.2 to 0.3 mm.
The feed-through 9 is preferably filled over 50 to 90%, particularly preferably 60 to 80%, of its volume with an insulating material 18 made of glass and/or containing glass ceramic.
The diameter of the thickening 19 is preferably at least 1.2 times, in particular 1.5 to 2.5 times, the diameter of the adjacent signal pin 7.
In this embodiment, the thickened portion 19 is 0.02 to 0.2mm, preferably 0.05 to 0.1mm long.
The length of the feed-through 9 may be in particular 0.5 to 2mm, preferably 0.8 to 1.5 mm.
The return loss of a TO package known in the prior art (thin curve) is compared with the return loss of a TO package according TO the present invention (thick curve) in fig. 9. It can be seen in particular that a return loss of about-10 dB has shifted from a frequency of about 30GHz to a frequency of about 50 GHz. The return loss is thus significantly improved.
The same applies to the insertion loss, which is plotted relatively in fig. 10. An insertion loss of 2dB is achieved near 60GHz rather than substantially above 30 GHz.
Thus, higher bandwidths of about 25GHz may be provided by the present invention.
Further measures for adapting the impedance curve of the feed-through are explained in more detail with reference to fig. 11 to 13.
Fig. 11 is a schematic cross-sectional view of another embodiment of a feedthrough 9 inserted into base 2.
In this embodiment, the signal pins 7 are also embedded in an insulating material 18 made of glass and/or glass ceramic. On at least one side, the feed-through 9 comprises a region 26 of increased diameter.
The region 26 of increased diameter is partially filled with an insulating material 18 made of glass and/or comprising glass ceramic.
By means of the region 26 of increased diameter, a reservoir is provided in which fluctuations in the volume of the insulating material 18 made of glass can be absorbed.
However, due to the increased diameter of the region 26, the filling level changes only slightly.
The presence of insulating material 18 in region 26 forms a mismatched disc that in turn reduces abrupt changes in impedance due to the presence of the cavity above.
The diameter of the region of increased diameter is preferably at least 1.2 times the diameter of the adjacent feed-through 9 and the length is 0.05 to 0.5mm, preferably 0.1 to 0.3 mm.
Fig. 12 shows how impedance matching can also be carried out by providing the signal pin 7 with a thickened portion 19 in the region 22 which is not filled with the insulating material 18.
Fig. 13 is a detailed view of the signal pin 7.
The signal pin 7 has a diameter d in the region of the non-thickeningiThe diameter is preferably between 0.1 and 0.5mm, particularly preferably between 0.2 and 0.3 mm.
In this exemplary embodiment, the thickening 19 is of stepped design, i.e. is of cylindrical design.
However, the thickened portion 19 may also have other shapes, in particular a chamfer at the front and/or rear. The thickened region 19 therefore merges not abruptly, but gradually to the maximum diameter da. This requires a gradually changing impedance curve.
The thickened portion 19 has a diameter daThe diameter preferably corresponding to the diameter diAt least 1.2 times, particularly preferably corresponding to the diameter di1.5 to 2.5 times.
The thickened portion 19 preferably has a length l of 0.02 to 0.2mm, particularly preferably 0.05 to 0.1mmv。
Length l of the connected excessüPreferably 0.2 to 0.5 mm.
The graph according to fig. 14 shows the return loss of an embodiment of the invention in which the feed-throughs have been filled with respective insulating materials made of glass having different dielectric constants.
It can be seen that the lower the dielectric constant of the insulating material made of glass, the more improved the return loss.
Fig. 15 shows the return loss of a TO package according TO the invention in case different glasses are used as insulating material and different fillers are used for the glass recessed areas of the feedthrough.
It can be seen that the return loss without filler (epsilonr filler 1, epsilonr glass 6.5) is the worst.
The optimum return loss can be achieved by using a glass with a low dielectric constant and at the same time using a filler whose dielectric constant matches that of the glass.
With reference to fig. 16, it will be explained by means of a schematic cross-sectional view how signal pins can be introduced eccentrically into the feedthrough 9 for impedance matching and/or for using a thinner substrate 5.
In this exemplary embodiment, a signal pin 7 is provided which is embedded in an insulating material 18 made of glass or glass ceramic and which is connected to the substrate 5 arranged on the carrier 4 by means of solder 8.
The feed-through 9 is only partially filled with an insulating material 18 made of glass.
Adjacent to the insulating material 18 made of glass, the recessed area is filled with a filler 24 made of plastic.
It can be seen that the signal pin 7 is eccentrically arranged in the feedthrough 9 and is thus displaced in the direction of the substrate 5.
The substrate 5 has a thickness of preferably 0.05 to 2mm, particularly preferably 0.1 to 0.2 mm. The substrate is preferably made of ceramic, in particular of aluminum oxide or aluminum nitrite.
The central axis of the signal pin is preferably offset by 0.01 to 0.15mm, particularly preferably 0.02 to 0.08mm, with respect to the central axis of the feedthrough 9.
The substrate 5 protrudes all the way into the area of the feedthrough 9, but is spaced from the signal pin 7 to allow inflow of solder 8.
The distance of the signal pin 7 from the substrate 5 is preferably between 0.05 and 0.3mm, particularly preferably between 0.1 and 0.2 mm.
Fig. 17 shows a perspective view of a kit of components for forming a TO package 1.
The TO package 1 consists of a base 2 and a lid 3 provided with a window 27.
The window 27 is designed in particular as a lens.
The base 2 can be equipped with optoelectronic modules, such as laser diodes and monitor diodes, after which the cover 3 is applied to the base, for example soldered (verschwei β t) or welded
It is also possible to attach the metal block 13 and the printed circuit board 12 provided with the reinforcement 11 after soldering the upper cover 3.
As already mentioned, it is advantageous here if the connection of the signal pins is separate from the supply of the ground connection.
Fig. 18 shows a schematic diagram of how the TO package is now assembled with the laser diode 28.
A mounting region 30 is formed on the substrate 5.
In this embodiment, the laser diode 28 is placed onto the conductive trace 6a present on the substrate 5 and is thus connected with the signal pin 7 a.
For contacting the signal pin 7b, a bonding wire 29 is provided, which connects the laser diode 28 with the electrically conductive track 6 b.
Since the conductive tracks 6a and 6b are directly opposite each other, the length of the bond wire 29 can be kept short, in particular less than 0.5 mm.
Fig. 19 to 21 show schematic cross-sectional views of a base with a feedthrough. Fig. 19 shows the insulation of the feedthrough 9 embedded in glass. When the glass is melted, a glass pull-up (Glashochzug)48 may appear at the signal pin 7. This affects the impedance and complicates the substrate. The thickening 19 is inside the cavity 25, which can be effectively prevented in the form of a recess in the feed-through 9. The example of fig. 20 shows an ideal case. The insulating material 18 ends here at the bottom of the thickening 19, so that the thickened region is located completely in the region not filled with insulating material 18 in the axial direction. In this case, abrupt impedance changes can be avoided by means of a suitably dimensioned thickening.
Fig. 21 shows a typical practical situation. The insulating material made of glass partially or completely wets the side surfaces 190 of the thickened portion 19. But at least the outwardly facing end surface 191 of the thickened portion remains free of insulating material. Wetting is more complicated due to the angle between the side surface 190 and the end surface 191, thus preventing glass pull-up as in the example of fig. 19. Although wetting of the side surface 190 may lead to an abrupt change in impedance, it is assumed that the axial length l of the thickened portion isVLess than the wavelength of the transmitted signal, which is very low and tolerable. In particular, this feature is generally also provided by the axial length l of the thickened portion 19VLess than its maximum transverse dimension in the radial direction of the feed-through 9. In the preferred case of a circular thickening viewed in the axial direction, this maximum transverse dimension of the thickening in the radial direction is therefore then given by the diameter of the thickening. If this criterion is fulfilled, the thickened portion 19 has a plate-like, disk-like or collar-like shape. Due to the shape of the side surfaces 190 and the end surfaces 191, wetting of the thickened portion 19 and thus complete embedding in the insulating material 18 is avoided. According to a further embodiment, it is therefore assumed that the thickening 19 has a side surface 190 which is optionally partially embedded in the insulating material 18, wherein the thickening 19 also has an outwardly facing end surface 191 which remains at least partially free of insulating material and thus delimits the cavity 25 or forms part of the wall of the cavity 25.
The TO package can be provided in a simple manner by means of the invention, which enables higher data transmission rates.
List of reference numerals
1 TO package
2 base
3 cover
4 support
5 base plate
6a, 6b conductive trace substrate
7. 7a, 7b signal pin
8 welding flux
9 feed-through
10 pin
11 stiffener/thickened area
12 printed circuit board
13 Metal block
14 bottom surface
15a, 15b are arc-shaped
16a-16d ground conductive trace
17a, 17b signal conductive traces
18a, 18b are made of insulating material made of glass
19a, 19b signal pin thickening
20 plated through holes
21 top surface of the base
22 region of the feedthrough that is not filled with a filling material
23 through hole of base
24 packing made of plastic
25 cavity
26 region of increased diameter
27 window
28 laser diode
29 join line
30 installation area
48 glass pull-up part
5818 surface of
19019 side surface
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