DE19627426A1 - Light-triggered power thyristor using free-floating technology - Google Patents

Abstract

The thyristor (10) has a semiconductor disc (17) with a light-sensitive trigger zone (28) contained within a hermetically sealed housing (11) and provided with two parallel disc electrodes (16,19). The electrodes contact opposite sides of the semiconductor disc and the stack provided by the electrodes and the intermediate semiconductor disc is held together via a mechanical clamp (20a,20b). A second mechanical device (24,25) secures the stack in position relative to the housing.

Description

TECHNICAL AREA

The present invention relates to the field of Power electronics. It affects a light-ignitable lei amung semiconductor, especially thyristor, which one with half lead equipped with a light-sensitive ignition area covers the disc within a hermetically sealed closed housing is arranged, the housing two includes parallel, disk-like electrodes, the semiconductors washer without integral connection between two out same disks is arranged, and the stack from off Equalization disks and semiconductor wafer between the electrodes is held by pressure.

Such a power semiconductor is e.g. B. from the publication EP-A2-0 687 014 known.

The invention further relates to a method for together build such a light-ignitable power semiconductor.  

STATE OF THE ART

Light-ignitable thyristors (LTTs or Light Triggered Thyri stors) must have a current of the order of one ignite a few mA. This means that there is a displacement current (i.e. an induced by a voltage rise dV / dt Unwanted ignition from just a few mA can solve. The absolute, effective displacement current is thereby proportional to the area below the ignition sensitive Structure. A high dV / dt stability of the component can be there with the smallest possible structure sensitive to ignition (i.e. by making the light-sensitive ignition as small as possible area). This requires a small light stain, for example, by using an opti very small diameter fiber for feeding the ignition energy can be achieved.

The downsizing of the optical structures requires at Assembly of the component but also a good adjustment and Fixing the light guide in relation to the photosensitive Chen ignition area or the semiconductor wafer. Especially at the so-called "free-floating" technique, in which the half lead and on the top and bottom of the semiconductor adjoining shims from Mo to each other and are not cohesively connected to the housing, son mechanically fixed only by pressure (and electrically con are clocked) result from these requirements structural problems.

In the publication mentioned at the beginning there is a light ignitable thyristor in "free-floating" technology for adjustment and fixation of the internal structure has been proposed upper Mo shim by means of a ring, which around the  running edges of the shim and the adjacent Includes electrode of the housing, in the radial direction relative to fix to this electrode. The semiconductor wafer itself is by sticking to an inside protruding circumferential ring bead fixed to the insulating housing. The lower one Shim is relative to the (lower) adjacent one Electrode of the housing fixed by means of a centering pin. The (rigid) light guide is with its output end to the light-sensitive ignition area of the semiconductor wafer glued. Such a combined fixation and adjustment by means of guide elements (ring, centering pin) and adhesives (Semiconductor wafer, light guide) is not only complex and complicated but also prone to errors because the four one cell elements semiconductors, shims and light guides can be adjusted and fixed separately.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention, a light-ignitable Lei to create semiconductor semiconductors in "free-floating" technology, the is simple in structure and particularly in relation to the Easily adjust and assemble light ignition, as well a method of assembling such a power half head to specify.

The task is the beginning of a power semiconductor mentioned type solved in that the stack from the off equalization disks and the semiconductor wafer by first mecha African means regardless of the pressure of the electrodes hold and fixed, and that by the first mecha stacks held together and fixed second mechanical means relative to the housing or the elec is aligned and fixed. By the first means  can outside of the housing from the shims and the semiconductor wafer in a simple manner and fixed submodule can be assembled, which then by the second means out as a whole relative to the housing can be aligned and fixed.

A first preferred embodiment of the invention draws is characterized by the fact that the first mechanical means little least include an electrically insulating clip which the stack of shims and the Wraps around the semiconductor wafer and holds it together. Preferably that a plurality of brackets are provided which hold the stack enclose in a ring. The brackets or brackets are the best hen from an insulating material, preferably from a glass reinforced plastic. The slices of the stack can first adjusted with each other and then by the bracket or brackets in the adjusted position be fixed.

It is particularly advantageous if according to a preferred Development of this embodiment, the bracket or Cling an essentially U-shaped, to the stack side have open cross-section. The brackets can be so simple way to fix on the edge of the stack up be pushed without the lateral over the compensation protruding semiconductor wafer touches and ver is pushed. This can cause a slight clamping be enough that the U-legs of the bracket (s) when opening slide slightly elastic and be bent outwards with compress the stack of disks with their restoring force. It but it is also conceivable to achieve clamping by that the U-legs of the bracket (s) are slightly wedge-shaped forms are.  

Another preferred embodiment of the power half ter according to the invention is characterized in that the Power semiconductors essentially rotationally symmetrical a central axis is constructed, and that the second mechani means include a centering pin, which on the one hand into a first through hole in one of the compensating plates ben is fitted and on the other hand in a center hole in engages the adjacent electrode. Furthermore, the ser embodiment, a light guide is provided, which of outside through a bushing in the housing and to the led light-sensitive ignition area of the semiconductor wafer is, the through hole in the shim di is aimed directly at the light-sensitive ignition area, and the centering pin has a second through hole, in which the light guide with its output end guided and aligned to the photosensitive ignition area is. By using the centering pin for both Adjustment of the stack of disks relative to the housing as well for adjusting and fixing the light guide relative to the Semiconductor wafers are construction and adjustment of the arrangement significantly simplified and made safer.

The inventive method for assembling a light-ignitable power semiconductor according to the invention characterized in that in a first step from the Semiconductor wafer and the two shims of the Sta pel is formed, the shims relative to the semiconductor wafer are aligned that in one second step of the stack so aligned by means of which he most mechanical means are held together and fixed, and that in a third step the held together and fixed stacks by means of the second mechanical means rela aligned and fixed to the housing or electrodes and is built into the housing. The one for the light injection  critical adjustment of the semiconductor wafer and off Equal disks can be successfully placed outside the housing The adjustment relative to the housing then only affects still the pre-adjusted stack as a whole.

The assembly is further simplified if according to one preferred embodiment of the method according to the invention the power semiconductor is essentially rotationally symmetrical is built around a central axis, as a second mechanical A centering pin is used to align the Stack relative to the housing of the centering pin on the one hand a first through hole in one of the shims is fitted and on the other hand with a center hole in the adjacent electrode is engaged when a light guide is also provided, which is from the outside through a bushing in the housing and to the light temp sensitive ignition area of the semiconductor wafer is guided Through hole in the shim at the first Step directly onto the photosensitive ignition area of the Semiconductor wafer is aligned, and with the fitting the centering pin of the light guide, which with its out aisle end in a second through hole in Zen is guided on the light-sensitive Zündbe richly aligned and fixed.

Further embodiments result from the dependent An sayings.

BRIEF EXPLANATION OF THE FIGURES

In the following, the invention is intended to be based on exemplary embodiments len are explained in connection with the drawing.

Show it  

Fig. 1 in cross section the internal structure of Favor th exemplary embodiment of a light triggered power semiconductor according to the invention; and

Fig. 2 different stages in the assembly of the Lei stungs semiconductors of FIG. 1st

WAYS OF CARRYING OUT THE INVENTION

In Fig. 1, the internal structure of a preferred embodiment of a light-ignitable power semiconductor according to the invention is shown in cross section. The light-ignitable power semiconductor 10 is housed in a housing 11 , which comprises, in a manner known per se, an outer, insulating ceramic ring 12 and two disk-shaped, parallel-aligned electrodes (for example made of Cu) which have welded-on annular flanges 13 and 14 are each connected to the ceramic ring (by a metal-ceramic connection) and thus form a gastight sealed housing. Between the electrodes 15 , 19 , a stack ( 29 in Fig. 2A) of three superimposed disks is arranged, which comprises a (lower) shim 18 , a semiconductor disk 17 and an (upper) shim 16 . The shims 16 , 18 are usually made of Mo and the nen to compensate for the different thermal expansion coefficients of the semiconductor wafer (made of Si) and the electrodes (made of Cu). The semiconductor wafer 17 contains the active semiconductor element, for. B. in the form of a thyristor.

The stack of disks is mechanically fixed by half-ring-shaped, electrically insulating clamps 20 a, b with a U-shaped cross section, which reach over the edge of the stack and hold the three disks 16 , 17 and 18 in a position adjusted to one another even without the housing 11 . The length of the U-legs of the brackets 20 a, b is chosen so that the semiconductor wafer 17 projecting since Lich is not touched by the brackets 20 a, b. The brackets 20 a, b are expediently made of an insulating material, preferably of a glass fiber reinforced plastic (GRP). The U-legs of the brackets 20 a, b are designed (for example wedge-shaped or resilient to the outside) such that when they are placed on the stack they exert a force in the direction of the central axis 30 on the stack, which compresses the stack and compresses it Slipping of the discs ben 16-18 prevented against each other safely. The brackets 20 a, b together form a bracket ring, which is held together by means not shown (e.g. an outer circumferential band or the like).

In the center of the semiconductor wafer 17 there is (on the underside) a light-sensitive ignition region 28 which must be irradiated with light to ignite the power semiconductor, in this case the Thyri gate. The required light is brought to the ignition area 28 through an optical fiber 22 in the form of a single thin, flexible optical fiber (diameter less than 100 microns). The light conductor 22 is via a hermetically sealed bushing 21 , which is expediently designed at the same time as a connection plug, guided into the housing 11 and runs there in a slot-like or groove-like recess 23 in the lower electrode 19 . The light guide 22 is guided with its output end through the central through hole ( 26 in Fig. 2B) in a centering pin 25 to the photosensitive ignition area 28 of the semiconductor wafer 17 , so that light from the light guide can fall directly and practically unimpeded on the ignition area 28 .

The centering pin 25 (stepped in the outer diameter) is fitted into a corresponding through hole ( 27 in FIG. 2) in the lower shim 18 . In this way, the correct adjustment of the centering pin 25 and thus of the light guide 22 is ensured by adjusting the through bore 27 of the lower shim 18 relative to the ignition area 28 . The centering pin 25 is also used to adjust and fix the stack of the disks 16 , 17 and 18 fixed by the clamps 20 a, b relative to the housing 11 or to the electrodes 15 , 19 . For this purpose, a centering hole 24 is seen in the lower electrode 19 , into which the pin 25 engages with its lower end when the power semiconductor 10 is assembled. The light guide 22 is thus mechanically fixed at both ends. Ther mix-related shifts of the individual elements are still compensated for by the fact that the light guide 22 is sufficiently flexible due to its small diameter.

The power semiconductor from FIG. 1 is preferably assembled in the steps shown in FIG. 2. In a first step ( FIG. 2A), a stack 29 is formed from the semiconductor wafer 17 , which contains the photosensitive ignition region 28 , and the two shims 16 , 18 . The shims 16, 18 are thereby aligned relative to the semiconductor wafer 17 so that the through hole 27 in the lower shim 18 directly out 17 on the photosensitive ignition region 28 of the semiconductor wafer is directed. In a second step ( FIG. 2B), the stack 29 aligned in this way is held together and fixed by means of the clips 20 a, b. After this fixation, the Zen trier pin 25 with the glued light guide 22 , both of which are already connected to the housing 11 via the bushing 21, can be fitted into the through hole 27 provided in the lower shim 18 .

In a third step ( FIG. 2C), the stack 29 held together and fixed by the clamps 20 a, b and provided with the centering pin 25 is inserted into the housing 11 (which is still open at the top), the stack 29 being inserted into the housing 11 Centering hole 24 engaging centering pin is aligned and fixed relative to the housing 11 or to the electrode 19 . Then the housing 11 can be closed by placing the upper electrode 15 with the welded ring flange 13 and connecting it to the ceramic ring 12 . In this way, a precise and safe adjustment and fixation of the light guide to the light-sensitive ignition region 28 of the half-conductor disk 17 is achieved with simple means, which is also and in particular suitable for thin optical fibers. The final and operational fixation and contacting of the stack 29 it finally follows by compressing the electrodes 15 and 19 when the power semiconductor 10 is installed in a circuit.

Reference list

10th light-ignitable power semiconductors
11 casing
12th Ceramic ring
13,14 flange
15,19th electrode
16,18th Shim (Mo)
17th Semiconductor wafer
20tha, b bracket
21 Implementation (connector)
22 Light guide
23 Recess (slot-like)
 24th Center hole
25th Centering
26 Through hole (pin)
27 Through hole (shim)
28 photosensitive ignition area
29 stack
30th Central axis

Claims (12)

1. A light-ignitable power semiconductor (10), and in particular thyristor which an equipped with a light-sensitive ignition region (28) the semiconductor wafer (17) about understood that ses within a hermetically sealed Gehäu is arranged (11), said housing (11) has two paral Lele, disc-like electrodes ( 16 , 19 ), the semi-conductor disc ( 17 ) is arranged without a material connection between two shims ( 16 , 18 ), and the stack ( 29 ) from shims ( 16 , 18 ) and semiconductor washer ( 17th ) between the electrodes ( 15 , 19 ) by pressure ge, characterized in that the stack ( 29 ) from the shims ( 16 , 18 ) and the semiconductor wafer ( 17 ) by first mechanical means ( 20 a, b) regardless of Pressure of the electrodes ( 15 , 19 ) is held together and fixed, and that the stack ( 29 ) held together and fixed by the first mechanical means ( 20 a, b) is secured by second mechani cal means ( 24 , 25 ) is aligned and fixed relative to the housing ( 11 ) or the electrodes ( 15 , 19 ). 2. Power semiconductor according to claim 1, characterized in that the first mechanical means comprise at least one electrically insulating clip ( 20 a, b), the edge of the stack ( 29 ) from the shims ( 16 , 18 ) and the semiconductor wafer ( 17 ) embraces and holds together. 3. Power semiconductor according to claim 2, characterized in that a plurality of brackets ( 20 a, b) is provided, which brackets ( 20 a, b) enclose the stack ( 29 ) in an annular manner. 4. Power semiconductor according to one of claims 2 and 3, characterized in that the bracket or brackets ( 20 a, b) consist of an insulating material, preferably of a glass fiber reinforced plastic (GRP). 5. Power semiconductor according to one of claims 2 to 4, characterized in that the bracket or brackets ( 20 a, b) have a substantially U-shaped cross-section open to the stack side. 6. Power semiconductor according to one of claims 1 to 5, characterized in that the power semiconductor ( 10 ) is constructed substantially rotationally symmetrically about a central axis ( 30 ), and that the second mechanical means comprise a centering pin ( 25 ) which, on the one hand, into a first Through hole ( 27 ) in one of the shims ( 18 ) is fitted and on the other hand engages in a centering hole ( 24 ) in the adjacent electrode ( 19 ). 7. Power semiconductor according to claim 6, characterized in that a light guide ( 22 ) is provided, wel cher from the outside through a bushing ( 21 ) in the housing ( 11 ) and to the photosensitive ignition area ( 28 ) of the semiconductor disc ( 17 ) is guided that the through hole ( 27 ) in the shim ( 18 ) is aligned directly with the light-sensitive ignition area ( 28 ), and that the centering pin ( 25 ) has a second through hole ( 26 ) in which the light guide ( 22 ) guided with its output end and aligned to the photosensitive Zündbe range ( 28 ). 8. Power semiconductor according to claim 7, characterized in that the light guide ( 22 ) is designed as a single, flexi ble optical fiber. 9. A method of assembling a light-ignitable power semiconductor according to claim 1, characterized in that in a first step, the stack ( 29 ) is formed from the semiconductor wafer ( 17 ) and the two shims ( 16 , 18 ), the shims ( 16 , 18th ) are aligned relative to the semiconductor wafer ( 17 ), that in a second step the stack ( 29 ) thus aligned is held together and fixed by means of the first mechanical means ( 20 a, b), and that in a third step the and fixed stack ( 29 ) is aligned and fixed relative to the housing ( 11 ) or the electrodes ( 15 , 19 ) by means of the second mechanical means ( 24 , 25 ) and installed in the housing ( 11 ). 10. The method according to claim 9, characterized in that at least one electrically insulating clip ( 20 a, b) is used as the first mechanical means, the edge of the stack ( 29 ) from the shims ( 16 , 18 ) and the semiconductor wafer ( 17 ) grips and squeezes. 11. The method according to any one of claims 9 and 10, characterized in that the power semiconductor ( 10 ) is constructed substantially rotationally symmetrically about a central axis ( 30 ) that a Zen trier pin ( 25 ) is used as the second mechanical means, and that for Aligning the stack ( 29 ) relative to the housing ( 11 ) of the centering pin ( 25 ) on the one hand into a first through hole ( 27 ) in one of the shims ( 18 ) and on the other hand with a centering hole ( 24 ) in the adjacent electrode ( 19 ) in Intervention. 12. The method according to claim 11, characterized in that a light guide ( 22 ) is provided, which from the outside through a bushing ( 21 ) in the housing ( 11 ) and to the photosensitive ignition area ( 28 ) of the semiconductor wafer ( 17 ) is that the through hole ( 27 ) in the shim ( 18 ) in the first step is aligned directly with the photosensitive ignition area ( 28 ) of the semiconductor wafer ( 17 ), and that with the fitting of the centering pin ( 25 ) of the light guide ( 22 ), which is guided with its output end in a second through hole ( 26 ) in the centering pin ( 25 ), is aligned and fixed on the light-sensitive ignition area ( 28 ).