DE3429282A1 - Optoelectronic module - Google Patents

Abstract

Having [sic] an optoelectronic component inside a housing. The component is mounted on a board/chip carrier which can be adjusted inside the housing. <IMAGE>

Description

OBtoelectronic module

The invention relates to an improvement in the special optoelectronic Module that is specified in the preamble of claim 1 and that for itself is very familiar to the specialist.

In particular, the invention represents an improvement of the patent applications P 34 06 424.9 (VPA 84 P 1141 DE) and P 34 09 146.7 (VPA 84 P 1204 DE), which were not previously published. The invention is also closely related to the applications with the same priority. .. (84 p The fastening of the component in the module is improved by the measures specified in claim 1. The invention and its developments are explained in more detail using the various exemplary embodiments or views shown in the figures, with FIG. 1 being a section through an example of a housing, FIG. 2 being a section through the plate with component, FIG Circuit diagram, FIG. 4 a view of the side of the plate shown in FIG. 2 which faces away from the lens, FIG. 5 a view of that side of the plate shown in FIG. 2 which faces the lens, FIG. 6 an illustration of how a fastening by welding , e.g. spot welding is possible on the adjusting ring, Figure 7 enlarged views of the welding points, Figure 8 a cross section through another embodiment of the housing especially for a light transmitter and Figure 9 a representation of how a particularly good heat-conductive attachment to the adjusting ring is possible by spot welding.

The component and the chip carrier / plate are in the one shown in FIG The example shown is not attached directly to the base plate, but at a distance to the base plate. This creates an electrical separation of the potential of the base plate possible from the potential of the component / chip carrier.

The component, see. PIN photodiode is back-lit, see. Figures 1 and 2, in particular the input capacitance of the preamplifier stage VVI, see.

FIG. 4, remains minimal - in the exemplary embodiment shown in FIG this preamplifier vvl is attached next to the diode, so not like in the registration P 34 09 146.7; the preamplifier VVI together with the component PIN-Pd (PIN photodiode) however, in principle, as in application P 34 09 146.7, a single structural unit can also be used form. By reducing the input capacitance of the preamplifier stage VVI and by the high-frequency lines that can be made particularly short in the invention Component, the bit rate (Mbit / sec) can be made particularly high. Is favorable the pin photodiode To be attached and constructed in such a way that the input capacitance, which acts on the preamplifier is, if possible, less than approx. 0.5 pF. The Xin photodiode itself has a capacitance between its p-n junction and contact pad of approx. 0.3 pF, if there are no other potential-bearing surfaces on the anode side. By Such dimensions can be achieved with bit rates of well over 50 Mbit / sec.

The pin photodiode sits on the ~ backside "of a hole in the chip carrier in the examples shown in FIGS. 1, 2, 4 and 5, especially about shadowing effects to avoid; - instead of the staggered / stepped bore shown there, you can also a conical hole to be attached there. As shown in Figure 2, the Radiation cone e.g. an angle of approx. 30 degrees for lenses with the usual refractive index (approx. 1.5). In principle, it is also possible to produce such bores Use laser beams, ultrasound or diamond burs, with particular reference to As well as possible well-defined cone angles and inclined bore axes should be observed as well as sharp edges at the transition to the board surface should be avoided as far as possible should. The hole should therefore be designed as possible so that it allows the optimize the optical coupling between the glass fiber and the window of the pin photodiode , in particular to adjust accordingly.

The chip carrier is preferably made of "green ceramic", e.g. punched, printed with thick film pastes, composed of two layers ß e.g.

200 #> icke, as well as sintered in a continuous process.

Such a method allows, as well as by means of pressing technology in each case to achieve defined conical or stepped bores. To do this, laser beam drilling needs Ultrasonic drilling or diamond drilling therefore not necessarily be used, which is cheap in terms of price and effort.

In principle, however, the chip carrier can also be manufactured by pressing techniques which is particularly economical for very large quantities.

The parting plane between the two layers of the chip carrier, cf. Fig. 2 and 1, can additionally contain an electrical shield / metal layer, can even be designed as an electrode of a capacitor. This can be beneficial be used to at least one more capacitor or more further capacitors in addition to the two capacitors shown in FIGS. 2, 4 and 5 Chip-C with their # housing 805 or 504 (smaller version) and their connections CB, CK (Figure 4) to be able to attach. On the front and on the back on the chip carrier there is hardly any space left for additional capacitors. With some 2 of the metallized surface at a distance of 0.2 mm results in a capacitance of approx. 2-3 pF, which can be useful in terms of high frequency technology.

Both the front and the back of the chip carrier can So carry additional electronic components and conductor structures, cf.

the capacitors mentioned, which is particularly important when using the ~ green ceramic "easily possible is.

The fastening points are also on the back of the chip carrier the pins glazed in the base plate are designed as blind holes, cf.

Figure 1, 2 and 4, for good contacts with solder or conductive silver adhesive and to ensure sufficient mechanical strength. Easy to put on of the chip carrier on the end faces of the pins would already result in secure contacts, but often too. low mechanical strength of the connections (vibration test, mechanical shock tests up to 1000g). By using blind holes also the flatness of the face / top and the positional accuracy of the face achieved with simple means with sufficient tolerance, both on the face and can be contacted and held on the surface of the pins.

An FET, for example, can also be attached to the chip carrier, deviating from the circuit example according to Figure 3. The IC technology and the concept of the The preamplifier W1 can therefore be adapted to meet your needs.

The pin photodiode is on after the assembly of the chip carrier the pins of the base plate are no longer mechanically accessible and are therefore well protected, if you disregard the stepped / conical bore. So the pin photodiode is Well protected against mechanical and environmental chemical influences.

However, the pin photodiode is electrical, e.g.

for test purposes or for damage analyzes (at least via one pole directly) accessible, see also Figure 3. This is important for "burn-in", for mounting tests and for qualifications, whereby the examination is also independent of the function of the preamplifier.

When assembling the housing, laser spot welding can also be used for fixing can be applied.

The parts connected in this way are, if they are themselves conductive, then galvanically securely connected to each other, which provides a shielding effect against high-frequency interference is improved or ensured, cf. in particular FIG. 1 with FIG. 6, 7, 8 and 9 showing the spot welding between the adjustment ring and the bottom plate in detail explain; -the adjustment ring and the base plate is very detailed as an example explained in the aforementioned application P 34 06 424.9 (84 P 1141).

Fixing / fastening alone, for example by gluing, would not sufficiently guarantee the shielding effect. The shielding effect is, however, generally required both against the external environment outside the module housing (the input of the preamplifier W1 with a very high input resistance would represent a good receiving antenna and transmitting antenna for interference pulses from the environment / into the environment of the module), as well as against the au the preamplifier upstream / downstream stages / components within the same housing (see the priority registration P ...

and An # n.P34 06 424.9), such additional components in generally work purely digitally with extremely steep current pulse edges. The spot welding or laser welding can therefore eliminate the additional expense of shield plates between save the individual stages within the same housing, especially if the component is not a receiving photodiode but a light transmitting diode, e.g. IRED is, then often particularly high amounts of heat loss have to be dissipated to the outside in cooling media (see e.g. the registration with the same priority P ...... / 84P P 8 onac e.g.

200 mW power loss due to particularly low thermal resistance between the component and the housing surface). The service life in particular {Bechtsendioden (IRED) is shorter, the higher its junction temperature: n operation, so that good cooling extends the service life.

The laser welding, in particular spot welding, can be contactless be carried out e.g. in accordance with FIG. The mutual adjustment of the Parts to be welded take place beforehand - the subsequent contactless welding using a laser then has little effect on the adjustment afterwards.

The number of spot welds distributed on the circumference can be almost can be chosen at will. the end Figure 9 shows that e.g. 12, 16 or 20 welding points can be selected all around, with a certain optimum heat dissipation is achieved when the welding points overlap each other (e.g. 20 spot welds).

The higher the number of welding points, the lower the number Thermal resistance at the welded transition. The weld seam, especially the spot weld points, are preferably attached between the glass insulation of the pins, cf.

FIG 9. To protect the glass insulation are therefore in the vicinity of Glass insulation no more welds carried out, see FIG. 9; - Furthermore are the glass insulations themselves highly heat-insulating, not just galvanically insulating, whereby the heat flow does not flow over the glass beads, but between the glass beads continue through the welds to the adjusting ring. This heat flux is largely influenced by the material and the thickness of the base plate.

In the example shown in Figure 6, the adjustment arm is for the z-axis can be used simultaneously for the supply of potentials to the component, so that during the adjustment (also during the subsequent laser welding) to the opto-electronic Component can be supplied with its operating voltages, making the adjustment (and fixation) under optimal ler optical coupling between component and fiber can be adjusted under operating conditions. The adjusting arm for the z-axis it can be part of a handling device / machine, so that the adjustment / fixation including the optimization of the optical coupling can also be carried out fully automatically.

2 claims 9 figures

Claims (2)

Claims Gl optoelectronic module with an optoelectronic Component within a housing, characterized in that the component is on an adjustable plate / chip carrier within the housing is attached. 2. A method for producing the module, characterized in that at least some of the parts to be fastened together which are inside the housing be attached, in a way that conducts heat well by welding, e.g. spot welding, be connected to each other.