Microvalve and method for manufacturing a microvalve

The microvalve according to the invention is comprised of an electromagnetic drive and of a multilayer lower valve part, which are permanently bonded to one another and are manufactured separately from one another. The lower valve part includes at least one armature and a valve-closure element, which are axially movable, as well as a housing which at least partially surrounds this axially movable component of the microvalve. The layers of the lower valve part are built up one upon the other by means of (multilayer) electrodeposition. The microvalve can be used in fuel-injection systems of internal combustion engines.

FIELD OF THE INVENTION 
The present invention relates to a microvalve and to a method for 
manufacturing a microvalve. 
BACKGROUND INFORMATION 
A microvalve of bonded layers is described in German Patent Application No. 
42 21 089, which describes a microvalve having three components placed one 
over one another as stacked layers. These components are composed of 
plastic material or aluminum. The closing element of the microvalve is 
made of a molded plastic, which contains metallic powder and is composed 
of several layers. To manufacture the valve, plastic molding processes are 
used, in particular injection molding or embossing (punching) to produce 
the structures. The strength or the chemical resistivity of the plastics 
employed is not always optimally adapted to the given work environments. 
SUMMARY OF THE INVENTION 
One of the advantages of the microvalve according to the present invention 
is that the microvalve can be manufactured cost-effectively and in a 
simple manner using metal. Thus, all the positive properties of metal are 
attained for the microvalve. The individual, metallic, electrodeposited 
components of the microvalve can be produced with narrower tolerances and, 
at the same time, with lower manufacturing costs than has been possible in 
the manufacturing of microvalves in conventional methods heretofore. 
Another advantage of the microvalve according to the present invention is 
that there is no compensation of the forces and torques acting on the 
valve-closure element, as occur when working with conventional 
microvalves. Otherwise, conventional pressure-compensated microvalves have 
large, highly stressed membranes. 
The design of the pressure-compensated microvalve according to the present 
invention yields the advantage that no mechanically, highly stressed 
membrane is needed as a structural element. The need has been eliminated 
for mutual dependency of the valve lift, of the fluid pressure to be 
controlled (switched) and of the lateral dimensions (dimensions in the x-, 
y-direction) of the microvalve. As a result, variants can be manufactured 
which feature a small volumetric flow and a large valve lift. 
It is further advantageous that different atomizer structures are able to 
be integrated very simply with the galvanic metal deposition 
(electrodeposition) on the microvalve. Thus, metallic layers, which in the 
end make up an "S-type spray-orifice plate" or an annular-gap nozzle, can 
be easily deposited. Such a galvanically deposited annular-gap nozzle on 
the microvalve renders possible a very uniform and fine atomization of the 
fluid. To this end, the annular-gap nozzle has at least one continuous 
annular gap, so that the fluid to be spray-discharged forms a cohesive, 
annular, jet lamella downstream from the annular gap. Further downstream, 
as its diameter increases, this lamella disintegrates into very small 
droplets. 
When S-type spray-orifice plates are used on the microvalve, besides an 
excellent atomization quality, exceptional, bizarre jet shapes can be 
advantageously produced. When working with single-, dual- and multi-jet 
sprays, these orifice plates render possible countless variations of jet 
cross-sections, such as rectangles, triangles, cross shapes, and ellipses. 
Such unusual jet shapes enable a precise and optimal adaptation to 
predefined geometric dimensions, e.g., when the microvalve is employed as 
a fuel injector, to different induction pipe cross-sections of internal 
combustion engines. 
Compared to macroscopic injectors, the small unit volume, the smaller power 
requirement of the drive, and the shorter switching time are advantageous. 
One of the advantages of the method according to the present invention for 
manufacturing a microvalve is that microvalve parts are able to be 
manufactured reproducibly, with great precision, cost-effectively, and 
simultaneously in very large quantities, because of their metallic 
construction, these microvalve parts being unbreakable and being able to 
be installed very simply and inexpensively by means of bonding, soldering 
or welding on other valve components, such as pot magnets. The process 
steps according to the present invention allow considerable design 
freedom, since the contours can be freely selected for the most part. 
Methods, such as UV depth lithography, dry-etching, or ablation by means 
of micro-electroplating (electrodeposition out of aqueous electrolytes) 
are advantageously combined to deposit thin metallic layers, each time 
with new structures (patterns), on one another. The process according to 
the present invention suited for building up two, three or more layers to 
form a microvalve. 
It is further advantageous for two layers of the microvalve to be built up 
in one electrodeposition step, the "lateral overgrowth" action of the 
electroplating being utilized. With the additional application of a 
galvanic starting layer and a new photoresist layer, the growing of the 
metal is continued selectively over the photoresist pattern of the 
preceding layer. A clear savings in costs and time is achieved with the 
aid of the lateral overgrowth.

DETAILED DESCRIPTION 
Microvalve 1 shown cross-section in FIG. 1 generally includes two 
cooperative basic components: 
Microvalve 1 depicted in cross-section in FIG. 1 is mainly comprised of two 
cooperating basic components, of an electromagnetic drive 2 for actuating 
microvalve 1, and of a lower valve part 17 including an actuating part 3 
that performs the valve function. Drive 2 is includes, for example, a 
cylindrical pot magnet 5, in which a soilenoid coil 6 is integrated. 
Solenoid coil 6 formed concentrically around a longitudinal valve axis 8 
is completely surrounded, radially to the inside and outside, by pot 
magnet 5. Running, for example, out of microvalve 1, on the side of 
microvalve 1 facing opposite actuating part 3, are two coil connections 9 
which ensure that current is supplied to solenoid coil 6. 
Since pot magnet 5 does not have any moving, sealing parts in the upper 
part of microvalve 1, it can be produced using precision manufacturing 
methods with relatively few tolerance requirements, such as punching, 
embossing, powder-injection molding, cutting-machining steps, erosion 
techniques, or metal-injection molding (MIM) methods. A conventional 
metal-injection molding method is a viable alternative for producing pot 
magnet 5 and entails the manufacturing of molded parts from a metal powder 
using an adhesive agent, e.g., a plastic adhesive agent, on conventional 
plastic-injection molding machines, and the subsequent removal of the 
adhesive agent and sintering powder of the residual powder-metal 
framework. The composition of the metal powder can thereby be simply 
matched to the desired, optimal magnetic properties of pot magnet 5. 
Solenoid coil 6 can be manufactured as a conventionally wound coil 
including one or more turns, as a stamping, or using a multi-layer thin or 
thick laminate structure. When a solid coil comprised of one turn is 
provided, it can also be pressed in the form of a metal strip into pot 
magnet 5. Thus, solenoid coil 6 and pot magnet 5 are provided with a 
wear-resistant, insulating layer. Pot magnet 5, provided with soilenoid 
coil 6, is assembled with a housing 12 of lower valve part 17, which 
substantially and radially surrounds actuating part 3 on the side facing 
away from pot magnet 5, using, e.g., bonding, welding, or soldering 
methods. Thus, housing 12 has a pot- or saucer-shaped design and, 
consequently, has an open area 14, in which actuating part 3 is embedded. 
A base plate 15 of housing 12 forming the downstream axial termination of 
microvalve 1 has an outlet orifice 16, which is formed concentrically to 
longitudinal valve axis 8 and communicates directly with opening area 14. 
Together with actuating part 3, housing 12, inclusive of base plate 15 and 
possibly integrated orifice plates or nozzle plates on base plate 15, 
forms lower valve part 17. Pot magnet 5, with its outer boundary edge, 
constitutes part of the overall housing of microvalve 1. 
Actuating part 3 arranged in open area 14 of housing 12 includes two 
permanently joined metallic layers, the layer facing pot magnet 5 
constituting a plate-shaped armature 18 having a circular cross-section 
and the layer pointing toward base plate 15 representing a disk-shaped 
valve-closure element 20. The magnetically soft armature 18 has, for 
example, a larger diameter, as well as a larger axial extent (thickness) 
than valve closure element 20. Together, these two elements making up 
actuating part 3 fill in open area 14 by about 3/4 . Given an overall 
diameter of microvalve 1 of, for example, 10 to 12 mm, armature 18 has, 
for example, a diameter of 7.5 mm and valve-closure element 20, for 
example, a diameter of 5.5 mm. The thicknesses of the metal layers, thus 
of armature 18, of valve-closure element 20, and of base plate 15 usually 
lie within the range of 0.1 to 1 mm. These size indications pertaining to 
the dimensions of microvalve 11, as well as all other dimensions indicated 
herein are given to further understanding and in no way restrict the 
insert. 
Actuating part 3 is directly coupled to housing 12, since web-and 
plate-like spring elements 24 are provided between an annular inner wall 
22 of housing 12 extending between pot magnet 5 and base plate 15, and 
armature 18. The three spring elements 24, e.g., disposed at 1200 
intervals from one another and running radially through open area 14 have, 
for example, a thickness of 0.1 mm and a width of 0.5 mm. The length of 
spring elements 24 is automatically given by the dimensions of armature 18 
and inner wall 22. Stop knobs 27, which hit against pot magnet 5 when 
microvalve 1 is open, are formed on one top front end 25 of armature 18 
facing pot magnet 5. Three or four of these stop knobs 27, for example, 
are expediently provided on armature 18. A sealing ring (gasket) 28, which 
projects out from a bottom end face 29 of disk-shaped valve-closure 
element 20 and represents the actual valve-closure element, runs on 
valve-closure element 20 and points toward base plate 15. Sealing ring 28 
is formed as a circumferential, annular elevation of valve-closure element 
20 that is small in width. A top end face 30 of base plate 15 represents a 
valve-seat surface area, at least in the area of sealing ring 28 of 
valve-closure element 20 that corresponds to base plate 15. 
The fluid to be controlled,(or switched) e.g., a fuel such as gasoline, is 
forced via one or more, e.g., radially running channels 32 in inner wall 
22, which serve as an inlet for a fluid, in accordance with the indicated 
arrow direction, into the high-pressure section, i.e., into open area 14 
of microvalve 1. If the valve is actuated, then the electromagnetic drive 
2 exerts an attractive force on actuating part 3. Sealing ring 28 is 
lifted up from valve-seat surface area 30, and microvalve 1 releases a 
fluid flow to outlet orifice 16 of microvalve 1. Armature 18 then strikes 
with its stop knobs 27 against pot magnet 5. The lift of actuating part 3 
is given by the height of open area 14 and of stop knobs 27, which, 
therefore, delimit the lift. Moreover, stop knobs 27 prevent armature 18 
from adhering to pot magnet 5. After pot magnet 5 has been interrupted, 
armature 18, together with valve-closure element 20, is moved by the fluid 
in open area 14 and spring elements 24 in the direction of valve-seat 
surface area 30, and microvalve 1 is closed. Thus, the path between the 
two described end positions of actuating part 3 represents the lift. The 
opening and closing travel of actuating part 3 is marked by an axially 
running double arrow. The closing force acting on armature 18 is the 
spring resilience of spring elements 24 plus a hydraulic force F, which is 
equal to the pressure difference .DELTA.p between open area 14 and the 
valve outlet, multiplied by the surface A of the valve outlet 
(F=.DELTA.p.times..pi.r.sup.2). The entire microvalve 1 has, e.g., an 
axial extent of 10 to 15 mm and is, therefore, very compact and requires 
only a very small installation space. When microvalve 1 is used, e.g., as 
a fuel injector on internal combustion engines, compared to conventional 
injectors presently used the result is an installation space that is 
reduced several times over to about 1/3 to 1/10. 
In the additional exemplary embodiments of FIGS. 2-8 the parts that have 
remained the same or that have the same function as in the exemplary 
embodiment described in FIG. 1 have the same reference numerals. FIG. 2 
shows a microvalve 1, which differs from the microvalve shown in FIG. 1 in 
the area of base plate 15. Base plate 15, for example, has been 
supplemented at the downstream end of microvalve 1, with an additional 
metallic layer that constitutes a spray-orifice plate 34. In its central 
area situated next to longitudinal valve axis 8, spray-orifice plate 34 
has at least one, and typically four spray orifices 35, which are 
contiguous to outlet orifice 16 of base plate 15. Spray-orifice plate 34 
can be part of the one-layer base plate 15 and, thus, be integrated in 
housing 12, or constitute an autonomous layer in addition to base plate 
15, or completely replace base plate 15 and, thus, also have valve-seat 
surface area 30. The surface area of an opening gap 37, which results 
between valve-seat surface area 30 and sealing ring 28, given an open 
microvalve 1, is two to four times as large as the sum of the 
cross-sectional areas of spray orifices 35 of spray-orifice plate 34. When 
microvalve 1 is open, the following pressure distribution adjusts itself. 
The system pressure of microvalve 1 is applied in open area 14; a portion 
of the pressure drops at opening gap 37, and the main portion of the 
pressure drops at the at least one spray orifice 35. The pressure 
difference between the high-pressure portion of microvalve 1 and the space 
between opening gap 37 and spray orifices 35 is great enough to ensure a 
reliable closing of microvalve 1. 
One of the distinguishing features of microvalve 1 shown in FIG. 3 is that 
a modified spray-discharge region is provided in the area of base plate 
15. Base plate 15 is designed, for example, in the form of a flat, 
circular, multi-layer plate (multilayer spray-orifice plate 38). Similarly 
to the preceding exemplary embodiment shown in FIG. 2, spray-orifice plate 
38 may constitute part of base plate 15 or replace base plate 15 in the 
sense that spray-orifice plate 38, itself, constitutes the entirety of the 
base of microvalve 1. In the exemplary embodiment shown in FIG. 3, 
spray-orifice plate 38 is designed as an "S-type plate", i.e., the inlet 
and outlet orifice in spray-orifice plate 38 are disposed in a staggered 
arrangement, which creates an "S-impact" in the flow of the fluid flowing 
through spray-orifice plate 38. The process steps in accordance with the 
present invention for manufacturing microvalve 1 and, in particular, 
spray-orifice plate 38 produce a structure which is composed of a 
plurality of layers. The manufacturing method will be described in greater 
detail below. 
Spray-orifice plate 38 is produced, e.g., from three metallic layers using 
electrodeposition methods. The depth-lithographic, electroplating 
manufacturing results in the following profiling features: 
layers having a substantially constant thickness over the entire plate 
surface area; 
due to the depth-lithographic patterning, substantially vertical notches in 
the layers, which each form the cavities that are traversed by flow; 
desired undercuts and overlapping of the notches because of the multi-layer 
structure of the individual, patterned metal layers; 
notches with any desired cross-sectional shapes, such as rectangle, 
polygon, rounded rectangle, rounded polygon, ellipses, circle, etc., that 
have substantially axis-parallel inner walls. 
The individual layers are electrodeposited one after another, so that the 
succeeding layer adheres permanently to the subjacent layer because of 
galvanic electroplating bonding. 
It is customary for spray-orifice plate 38 to have a top layer 41 with four 
inlet orifices 42, a bottom layer 43 with four outlet orifices 44 and, for 
example, a middle layer 45 situated between layers 41 and 43. Inlet 
orifices 42 are disposed, e.g., in the vicinity of longitudinal valve axis 
8, while outlet orifices 44 are spaced further away from longitudinal 
valve axis 8 and, thus, are offset radially from inlet orifices 42. Four 
radially running channels 46, which form a direct connection between inlet 
orifices 42 and outlet orifices 44, extend in middle layer 45. Channels 46 
are sized so as to just cover inlet orifices 42 and outlet orifices 44 in 
the drawing projection. Besides being radially offset, inlet orifices 42 
and outlet orifices 44 can also be additionally offset in the 
circumferential direction. 
The "S-impact" within spray-orifice plate 38, along with a plurality of 
vigorous flow deflections, causes a substantial, atomization-promoting 
vorticity to be impressed upon the flow. The velocity gradient 
transversely to the flow is especially pronounced as a result. It 
expresses the change in the velocity transversely to the flow, the 
velocity in the middle of the flow being perceptibly greater than near the 
inner walls. The elevated shear stresses in the fluid promote the 
disintegration into fine droplets at outlet orifices 44. Since the flow in 
the outlet is separated on one side because of the radial flow component 
impressed upon the fluid through channels 46, it does not experience any 
calming effect because of the lack of contour guidance. The fluid at the 
separated side experiences an especially high velocity, while the velocity 
of the fluid on the side of outlet orifices 44 falls off with applied 
flow. Thus, the atomization-promoting vorticities and shear stresses are 
not dissipated upon emergence. 
Many variations of spray-orifice plates 38 in the form of S-type plates are 
possible. Thus, instead of channels 46 joining in each case one inlet 
orifice 42 with one outlet orifice 44 in middle layer 45, it is 
conceivable to have only one contiguous, e.g., annular or square channel 
46. All inlet orifices 42 would then lead into this channel 46, and all 
outlet orifices 44, in turn, out of channel 46. Inlet orifices 42 and 
outlet orifices 44 can be offset from one another to the extent desired. 
The jet direction and the degree of vorticity can be regulated or adjusted 
based on the size of the offset. Besides the typical square or rectangular 
cross-sections of inlet orifices 42, outlet orifices 44 and channels 46, 
other cross-sectional geometrical shapes can be easily produced, such as 
rounded-off rectangles or squares, circles, circular segments, ellipses, 
ellipse segments, polygons, etc. The design of inlet orifices 42 and 
outlet orifices 44 can be varied on a spray-orifice plate 38. Suitable 
cross-sectional variations would be, for example, a transition from a 
square to a rectangle and vice versa, from a rectangle to a circle and 
vice versa, from an ellipse to a circle and vice versa. It is also easily 
possible for inlet orifices 42 and outlet orifices 44 to have different 
orifice widths. 
Microvalve 1 shown in FIG. 4 has an annular-gap nozzle 48 integrated in 
base plate 15. Annular-gap nozzle 48 differs primarily from the previously 
described spray-orifice plate 38 in the area of fluid outflow. Instead of 
a plurality of outlet orifices 44 in base plate 15, annular-gap nozzle 48, 
which in the same way as spray-orifice plate 38 has a three-layer design, 
has in bottom layer 43 a narrow annular gap 50 which is not interrupted 
over the periphery. In this case, annular gap 50 has a substantially 
larger diameter than does an annular opening 52 in the top layer 41 of 
annular-gap nozzle 48. Annular opening 52 can also be replaced by a 
plurality of inlet orifices 42 in conformance with the arrangement in 
spray-orifice plate 38 (FIG. 3). In middle layer 45, in turn, at least one 
channel 46 is provided, which establishes a connection between annular 
opening 52 and annular gap 50. 
Annular gap 50 enables thin, fluid, hollow lamellae to be spray-discharged, 
these hollow lamellae thinning out in the downstream direction behind 
microvalve 1. This thinning action is promoted by a corresponding increase 
in the lamellae circumference resulting from their tulip-shape. The free 
jet surface continues to increase in this manner, and the lamellae 
disintegrate into correspondingly smaller droplets. Moreover, the droplet 
packing density decreases with an expanding lamella cross-section, so that 
it is less likely that droplets recombine in the fuel spray to form larger 
drops (droplet coagulations). The lamellae disintegrate starting at a 
defined axial distance from annular gap 50. Because of aerodynamic 
reciprocal actions with the gas surrounding the lamellae, the lamella 
surface becomes more and more rippled (Taylor vibrations) as the distance 
to annular-gap nozzle 48 increases. The instability inherent in the 
lamellae becomes greater and greater with an increasing distance from 
annular gap 50 until a point where there is an abrupt disintegration into 
very small droplets. The advantage of this arrangement is that besides the 
ripple effect produced in the lamellae, virtually no other disturbances 
occur. Thus, for example, undesired local thickened areas, i.e., "strands" 
are avoided in the lamella that is thinning out in the downstream 
direction. 
It is imperative that the lamella remain uninterrupted over its 
circumference. Otherwise, two free lamella ends will form at a lamella 
parting spot and merge in accordance with the physics of the surface 
tension to form a thick bulge. This results in larger drops or strands at 
these spots. Besides, a lamella interruption means that the tulip-shaped 
lamella profile is disturbed. 
The advantages of annular-gap spray discharging indicated above also apply 
to an embodiment of the present invention illustrated in FIG. 5. In this 
microvalve 1, multi-layer base plate 15 or annular-gap nozzle 48 has a 
divided form. An outer annular region 54 is permanently joined as a part 
of housing 12 to inner wall 22 and to pot magnet 5. On the other hand, an 
inner nozzle region 55 is completely separate from outer annular region 
54, nozzle region 55, however, being part of movable actuating part 3. 
Thus, when microvalve 1 is opened and closed, nozzle region 55 
participates in the lifting movement of valve-closure element 20. Both the 
outer contour of nozzle region 55, as well as the inner contour of annular 
region 54 have, for example, a stepped design, the flow cross-section 
between nozzle region 55 and annular region 54 being the largest near 
valve-closure element 20. This largest flow cross-section can also be 
provided in base plate 15, as shown in FIG. 5. In the downstream 
direction, the orifice width diminishes, e.g., in steps, with each new 
layer until the width of the narrow annular gap 50 in bottom layer 43 is 
reached. 
Annular gap 50 is designed to have approximately similar diameter size as 
sealing ring 28 of valve-closure element 20. As a result, the available 
hydrostatic force for closing microvalve 1 profits from the entire 
pressure difference between the system pressure and the pressure 
prevailing outside of microvalve 1 and not just from part of this 
difference. Therefore, microvalve 1 is able to be closed more rapidly. 
FIG. 6 illustrates a microvalve 1 according to yet another embodiment of 
the present invention. In this microvalve 1, at least one channel 32' 
provided for supplying the fluid to the open area 14 of housing 12, in 
which actuating part 3 is moved axially, is configured parallel to 
longitudinal valve axis 8. Channel 32' runs, in this case, through pot 
magnet 5, e.g., over its full axial extent and then opens through into 
open area 14. Viewed in the circumferential direction, such a channel 32' 
can open through into open area 14 precisely where a spring element 24 
follows downstream in open area 14. In this exemplary embodiment of 
microvalve 1, valve-closure element 20 does not have any sealing ring. 
Rather, in the closed state of microvalve 1, the plate-like valve-closure 
element 20 rests with its bottom end face 29 directly against the top face 
30 (valve-seat surface) of base plate 15. However, the outside diameter of 
valve-closure element 20 is only slightly larger than the diameter of the 
central outlet orifice 16 in base plate 15, so that valve-closure element 
20 abuts sealingly with only a small outer annular sealing area 57 against 
valve-seat surface 30. However, this annular sealing area 57, in turn, 
must be large enough to guarantee an absolute seal tightness on the closed 
microvalve 1. Microvalve 1 is also equipped with a spray-orifice plate 38 
(S-type plate) similar to the third exemplary embodiment shown in (FIG. 
3), the S-impact of the flow being indicated by arrows. 
Another variant of an embodiment of microvalve 1 according the present 
invention includes a use of a permanent magnet. A permanent magnet 
arranged, e.g., on base plate 15 ensures that in the de-energized state of 
electromagnetic drive 2, armature 18 is pulled up with valve-closure 
element 20 toward valve-seat surface 30 and microvalve 1 is, thus, closed. 
If microvalve 1 is actuated, then pot magnet 5 pulls up armature 18 with 
valve-closure element 20 and thereby partially cancels out the effect of 
the permanent magnet. Microvalve 1 is now open. One can dispense with 
spring elements 24 in this exemplary embodiment. 
An especially suited and preferred method according to the present 
invention for manufacturing microvalve 1 or lower valve part 17 is 
illustrated in FIGS. 7 and 8. FIGS. 7 and 8 do not exactly reproduce the 
exemplary embodiments illustrated in FIGS. 1 through 6 of lower valve part 
17 with the corresponding, desired contours, but rather only those 
arrangements which clarify the manufacturing principle. However, the 
manufacturing process steps according to the present invention allow all 
exemplary embodiments to be manufactured at any time. 
Because of the high demands placed on the structural dimensions and the 
precision of injection nozzles or injection valves, micropatterning 
(microstructuring) methods used for their commercial manufacturing are 
gaining in significance today. The present invention describes a method 
for manufacturing microvalves or individual microvalve components that is 
based on the successive application of photolithographic steps (UV depth 
lithography) and on the subsequent micro-electroplating process. The 
method according to the present invention ensures a high precision of the 
structures, even on a large-surface scale, so that it can be applied 
ideally to a large-scale production. A multiplicity of lower valve parts 
17 for microvalves 1 can be produced simultaneously on one wafer (useful 
chip area) using the process steps according to the present invention. 
The method starts out with a flat and stable substrate 60, which can be 
made, e.g., of metal (copper), silicon, glass or ceramic. The thickness of 
this substrate 60 usually lies between 500 .mu.m and 2 mm; however, it has 
no effect on the subsequent process steps. After substrate 60 has been 
(scrubbed free of impurities) a metallic (e.g., Cu, Ti) or polymeric 
sacrificial layer 61 is applied by means of vapor deposition, sputter 
deposition, spin-on deposition, spray-on deposition or another suitable 
method. Following the complete batch processing of the useful chip (wafer) 
area, this sacrificial layer 61 is selectively removed, e.g., by means of 
etching, from substrate 60 to achieve a simple dicing and to lift off the 
components, thus, in this case (or operation) lower valve parts 17. A 
metallic galvanic starting layer 62 (e.g. Cu) is applied to sacrificial 
layer 61 by means of sputter deposition, vapor deposition, or by a 
wet-chemical treatment method (currentless electrodeposition). 
Galvanic starting layer 62 is needed for electrical conduction process for 
the later micro-eletroplating process in which metallic layers are 
electrodeposited in patterned photoresist layers. Galvanic starting layer 
62 can also be used directly as sacrificial layer 61. 
After substrate 60 has been pretreated in this way, a photoresist 63, such 
as the one mentioned above, is applied over the entire surface in a next 
process step. To this end, three different variants, in particular, 
present themselves: 
1. Lamination application of a non-removable resist at, e.g., about 
100.degree. C.; 
2. Spin-on or spray deposition of a liquid resist; or 
3. Spin-on or spray deposition of a polyimide in a liquid state. 
Photoresist 63 is applied in this case in one or more layers. 
After drying, photoresist 63 is present in a solid form in all three 
variants. Photoresist 63 usually corresponds in thickness to the metal 
layer, which should be realized in the electrodeposition process that 
follows later, thus, for example, should correspond, e.g., to the 
thickness of bottom layer 43 of spray-orifice plate 38 (FIG. 3). 
Typically, the aim is to have layer thicknesses of between 10 and 300 
.mu.m, depending on the desired thickness of the different layers of lower 
valve part 17. Thus, the layers of spray-orifice plate 38 are usually not 
as thick as, e.g., armature 18. The metal structure to be realized is 
supposed to be transferred inversely (as an inversion pattern) with the 
aid of a photolithographic mask in photoresist 63. It is possible here, on 
the one hand, for photoresist 63 to be exposed directly through the mask 
by means of UV irradiation (e.g., .lambda.=200 nm to 500 nm) (UV depth 
lithography). Another possibility for patterning photoresist 63 provides 
for an oxide (e.g. SiO.sub.2) or a nitride, which after being 
photolithographically patterned is used as a mask for a dry-etching 
process on photoresist 63. A laser ablation would also provide a solution, 
after the application of a mask, material of photoresist 63 being removed 
explosively with the help of a laser. 
Following development of the UV-exposed photoresist 63 or application of 
the other mentioned methods (dry etching, ablation), a desired pattern 
that is predefined by the mask is produced in photoresist 63. This pattern 
in photoresist 63 serves as a negative pattern for the later metallic 
layer 43 of spray-orifice plate 38 (FIG. 3). In the other exemplary 
embodiments as well, it is analogously a question of the bottom layer at 
the time, with which the build-up of the layered lower valve part 17 
begins. In the electrodeposition process step that follows at this point, 
a metal 65 or a metallic alloy is deposited out of an acqueous electrolyte 
into the resulting resist trenches. As a result of the electrodeposition, 
metal 65 is placed closely against the contour of the negative pattern of 
photoresist 63, so that the predefined contours can be reproduced true to 
form in metal 65. To produce multi-layer structures, the height level of 
the galvanic layer of metal 65 should correspond to the height of 
photoresist 63. Which deposition material is selected depends on the 
specific layer requirements, factors such as mechanical strength, chemical 
resistance, weldability, and others being especially significant. Usually, 
Ni, NiCo, NiFe, Cu, Fe, Co, Zn or Au are used; however other metals and 
alloys are also conceivable. 
To realize the structure of the complete lower valve part 17, the steps 
starting with the deposition of galvanic starting layer 62 must be 
repeated in conformance with the number of desired layers. Thus, following 
the resist patterning, the individual metal layers are repeatedly 
deposited on one another and are held together by means of metallic 
adhesion. It is possible for different metals 65 to be used as well for 
the layers and components of a lower valve part 17, so that it is by no 
means necessary for, e.g., armature 18 and spray-orifice plate 38 to be 
made of the same material. Prior to the next electrodeposition of metal, 
other adhesion-promotor layers produced, e.g. through PVD (physical vapor 
deposition) or a wet chemical treatment, can be applied, in addition to 
galvanic starting layers 62, to photoresist 63 and/or to the preceding 
metallic layer, through which means the quality of the bond joining the 
individual layers to one another can be improved. 
The lower valve parts 17 are subsequently diced. Thus, sacrificial layer 61 
is etched away, through which means lower valve parts 17 are lifted off 
from substrate 60. The galvanic starting layers 62 are subsequently 
removed by means of etching, and the remaining photoresist 63 is dissolved 
out of the metal patterns. This can be achieved, e.g., by means of a KOH 
treatment or through an oxygen plasma, or by means of solvents (e.g. 
acetone) in the case of polyimides. These processes of dissolving out 
photoresist 63 are generally known as "stripping". It is likewise 
conceivable to mechanically loosen substrate 60, e.g. by means of magnets, 
given a properly selected galvanic starting layer 62. A dicing by means of 
ultrasound is just as feasible. 
It is clearly shown in FIG. 7 that it is especially beneficial for the 
metallic layer for spring elements 24 to be deposited between armature 18 
and valve-closure element 20. This metallic layer projects out radially in 
some areas radially over the outer boundary edge of armature 18 in 
conformance with the desired number of spring elements 24. If the 
intention is to manufacture structures with slanted or rounded side walls, 
this can be done through a "lateral overgrowth" 68 method. In this method, 
two desired layers of lower valve part 17 can be formed in one step by 
means of electrodeposition. FIG. 8 illustrates lateral overgrowth 68 on 
the basis of two layers denoted by reference numerals 41 and 45. Metal 65 
to be galvanically deposited initially grows in the known form around 
photoresist pattern 63 of layer 45 up to the top edge of photoresist 63 
and then beyond photoresist 63. The overgrowth 68 of photoresist pattern 
63 is formed in the horizontal and vertical direction, roughly in the same 
order of magnitude. This partial overgrowth 68 replaces the application of 
an additional galvanic starting layer 62 on photoresist 63 and of a next 
galvanic layer, per se, since two layers 45, 41 of lower valve part 17 are 
produced in one electrodeposition step. In this manner, inlet orifices 42 
can be produced very selectively, e.g., in top layer 41 of spray-orifice 
plate 38 shown in (FIG. 3). The lateral overgrowth 68 forming must be 
stopped at certain times to obtain the desired orifice sizes. On the other 
hand, another photoresist layer 63 at the axial height of overgrowth 68 
can also be provided, which, in the final analysis, is used as a stop 
means for the lateral overgrowth 68 of layer 41 and guarantees a precisely 
defined size for inlet orifices 42. 
To separate those structures, which later are required to be movable 
relatively to each other (see FIG. 5), a suitable sacrificial layer 61' is 
applied at the spots to be separated, as shown in FIG. 7. This can be, in 
particular, a titanium or copper layer produced through PVD, which, prior 
to the deposition of the following metallic layer that will later belong 
to the movable part (nozzle area 55) of microvalve 1, is applied to the 
preceding layer of the later non-removable annular region 54. 
Prior to or subsequent to the removal of sacrificial layers 61, 61' of 
galvanic starting layers 62 or of photoresist 63, the necessary bonding 
processes (e.g., adhesion, welding, soldering) can be undertaken to join 
lower valve part 17 and pot magnet 5.