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DESCRIPTION JPH0865797

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DESCRIPTION JPH0865797
[0001]
FIELD OF THE INVENTION The present invention is applicable to the manufacture of acoustic
transducer arrays, in particular to electrically connect the individual transducer elements of the
acoustic transducer array with the respective circuit elements. The present invention relates to a
method of manufacturing a support layer for an acoustic transducer used in an array.
[0002]
BACKGROUND OF THE INVENTION Ultrasonic imaging devices are widely used to form an image
of the internal structure of a subject or object of interest. Diagnostic ultrasound imaging devices
used in medicine form an image of the internal tissue of the human body by electrically exciting
the acoustic transducer or acoustic transducer array to generate short ultrasonic pulses that are
fed into the human body. Do. Echoes from tissue are received by one or more acoustic
transducers and converted into electrical signals. Circuit elements such as printed circuit boards,
flexible cables or semiconductors receive the electrical signals. The electrical signals are
amplified and utilized to form a cross-sectional image of the tissue. These imaging techniques
provide a safe, non-invasive method for obtaining a diagnostic image of the human body.
[0003]
An acoustic transducer for emitting ultrasonic pulses comprises a plurality of piezoelectric
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elements arranged in an array at a predetermined pitch. This array is generally one or two
dimensional. By reducing the pitch of the piezoelectric elements in the array and increasing the
number of elements, it is possible to increase the resolution of the image. The operator of the
imaging device is able to control the phase of the electronic pulses applied to the respective
piezoelectric elements in order to change the direction of the output ultrasound beam or its
focus. In this way it is possible to "steer" the ultrasound in order to illuminate the desired part of
the specimen without having to physically manipulate the position of the transducer.
[0004]
When one of the piezoelectric elements is energized, sound waves are emitted from both the
front of the piezoelectric element facing the imaging target and the back of the piezoelectric
element. It is desirable that the acoustic energy from the back be greatly attenuated so as not to
adversely affect the resolution of the image. Without attenuation, acoustic signals traveling
backwards may reflect from the circuit elements back to the surface of the transducer and
degrade the desired electrical signal.
[0005]
To correct this situation, a support layer of acoustic damping material is inserted between the
piezoelectric element and the circuit element to attenuate unwanted acoustic energy from the
back of the piezoelectric element. Ideally, the acoustic impedance of the support layer matches
the impedance of the piezoelectric element such that a significant portion of the acoustic energy
from the back of the piezoelectric element will be coupled to the support layer.
[0006]
A problem associated with using a support layer between the piezoelectric element and the
circuit element is that of providing electrical interconnections between the particular
piezoelectric element and the associated circuit element. The interconnection problem is even
more difficult in the case of a two-dimensional array of four or more rows and columns, since the
internal elements do not have exposed edges that easily accommodate electrical connections. In
such a two-dimensional array, the electrical interconnections between the individual piezoelectric
elements and the electrical circuitry receiving and processing the electrical signals are generally
implemented in the Z-axis direction perpendicular to the array. However, as the number of
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elements in the array increases and the pitch between elements narrows, the formation of this
interconnect becomes increasingly difficult.
[0007]
[0007] One of the methods to enable interconnection by the support layer is US Patent entitled
"ULTRASONIC TRANSDUCER AND METHOD FOR FABRICATING THEREOF" (Ultrasonic
Transducer and Method of Making the Same) by Kawabe et al. Is disclosed in the Kawabe teaches
the use of a printed wiring board directly coupled to an array of piezoelectric transducers. The
support layer is shaped in an array around the substrate such that the substrate extends
outwardly from the shaped support layer. Kawabe discloses a reliable interconnection method,
but the wiring substrate results in the formation of an unwanted reflective surface of the acoustic
energy in the support layer, which makes it possible to use the useful acoustic attenuation
properties of the support layer. Some changes will occur.
[0008]
Another method is the sound attenuating material as disclosed in US Pat. No. 5,267,221 entitled
"BAKING FOR ACOUSTIC TRANSDUCER ARRARY" (support for acoustic transducer arrays) by
Miller et al. Form the entire support layer from the continuous block of Because the continuous
support layer is generally free of internal obstacles such as Kawabe's wiring substrate, the
support layer as a whole has improved acoustical attenuation capabilities. Nevertheless, the
manufacture of a continuous support layer requires that the fragile conductor be screwed into
the hard support layer in order to prevent breakage. In practice, this is a task that is quite
difficult to achieve, especially in the case of large matrix-sized acoustic arrays, which are
relatively narrow in pitch and have a large number of individual conversion elements. As a result,
continuous structured support layers, despite other distinct advantages, do not lend themselves
to certain large scale manufacturing techniques.
[0009]
Accordingly, there is a need for an improved method of manufacturing a support layer that
enables electrical interconnection between elements of an acoustic transducer array and
corresponding contacts of an electrical circuit element. It is done. Such a support layer allows
sufficient attenuation of the acoustic energy output from the back of the piezoelectric element,
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while it is desirable to prevent internal reflection of such energy from returning to the transducer
element. It is desirable that this manufacturing method be cost effective and be easily adaptable
to large transducer arrays consisting of a large number of piezoelectric elements with relatively
narrow pitches.
[0010]
SUMMARY OF THE INVENTION According to the teachings of the present invention, a Z-axis
support layer of an acoustic transducer is obtained. This support layer consists of a matrix of
electrical conductors arranged in parallel and embedded in an electrically insulating acoustically
damped support material. An acoustic transducer is disposed at the first end of the support layer,
and the individual transducer elements are each electrically connected to each of the electrical
conductors. At the other end of the support layer, the conductors are electrically connected to the
corresponding circuit elements.
[0011]
In an embodiment of the present invention, the support layer is manufactured from a plurality of
leadframes each comprising an outer frame member and a plurality of conductors extending
parallel across the leadframe. The conductors terminate at both ends of the frame member. A
plurality of leadframes are stacked such that the respective conductors of adjacent leadframes of
the leadframes are arranged in parallel to form a space corresponding to the width of one
leadframe between the respective conductors. Will be By pouring the sound absorbing support
material into a plurality of stacked lead frames, the space between the conductors is completely
filled. Next, the frame member and the overly sound absorbing support material are removed
from the plurality of lead frames that are stacked and poured the support material.
[0012]
Specifically, the step of providing the plurality of leadframes further includes the step of applying
a photoresist material to the sheet of leadframe material. A trace pattern comprising a plurality
of leadframes is imaged into the photoresist material. The leadframe material is selectively
etched and the etched leadframe material is passivated. Next, the lead frames are individually
separated for use in the support layer.
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[0013]
The step of pouring the support material further includes the step of evacuating the plurality of
stacked lead frames having the support material poured thereon for a first period of time. Next, a
predetermined amount of pressure is applied to the plurality of leadframes stacked and poured
support material. Finally, a plurality of stacked and poured support material leadframes are
heated to a predetermined temperature for a second period of time. Once released from the high
temperature bake, the stacked, poured lead material lead frames are subjected to grinding until
the desired dimensions and flatness are obtained.
[0014]
Those skilled in the art will appreciate the z-axis conductive support layer for acoustic
transducers utilizing an etched lead frame by reviewing the following detailed description of the
preferred embodiment. Will be more complete, as will its additional benefits and objectives.
Reference is made to the drawings in the attached drawing which are schematically depicted
first.
[0015]
DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, an
improved sound attenuating support layer is provided which enables electrical interconnection
between elements of an acoustic transducer array and corresponding contacts of an electrical
circuit element. The way is obtained. This method can be easily adapted to a relatively small
pitch, large transducer array consisting of a large number of piezoelectric elements.
[0016]
Referring first to FIG. 1, an acoustic transducer phased array 10 is shown. As shown, a typical
sound wave 5 is emitted from the central portion of the acoustic transducer phased array 10. The
acoustic transducer phased array 10 is comprised of a matching layer 12, a piezoelectric layer
14, and a support layer 16. The piezoelectric layer 14 provides an acoustic resonator that
generates sound waves in response to electrical signals. Sound waves are delivered from both the
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upper surface 13 of the piezoelectric layer 14 and the lower surface 15 which is the back of the
piezoelectric layer. The piezoelectric layer 14 can be composed of any material, such as lead
zirconate titanate, which generates sound waves in response to an electric field applied thereto.
The matching layer 12 increases the forward power of the acoustic wave transmitted from the
piezoelectric layer 14 to the load. The support layer 16 functions to attenuate the sound waves
traveling from the back of the piezoelectric layer 14 and also enables electrical connection from
each piezoelectric element to an external circuit element.
[0017]
The piezoelectric layer 14 and the matching layer 12 are bonded to the support layer 16 using
an epoxy or other adhesive. The piezoelectric layer 14 and the matching layer 12 are then
divided into a plurality of independent piezoelectric elements 18 arranged in an array. The array
size is described in relation to its azimuthal direction (x-axis) and its elevation direction (y-axis).
For example, although FIG. 1 shows an acoustic transducer array consisting of 14 × 3 elements,
it is of course possible to construct arrays of other sizes in a similar manner. Two-dimensional
arrays can be made quite large, such as 64x64 or 128x128. By varying the phase of the electrical
signal applied to each piezoelectric element 18 as a particular transducer element, the resulting
acoustic signal can be selectively controlled or "steered".
[0018]
The lower surface 15 of the piezoelectric element 14 is shown in FIG. It is divided into a 14 × 3
array of individual piezoelectric elements 18. Conductive traces 22 as conductors extend in the zaxis direction through the support layer 16 and electrically connect with the piezoelectric
element 18 at the lower surface 15. Electrical signals for each piezoelectric element 18 are
conducted through conductive traces 22.
[0019]
The conductive traces 22 of the support layer 16 are fabricated from a plurality of lead frames,
as shown in FIGS. Lead frames are generally thin sheets of conductive material, such as BeCu,
used in the manufacture of integrated circuits. The lead frame can be selectively etched to
incorporate the desired pattern to enable electrical connection between the semiconductor
substrate of the integrated circuit and the external circuitry. For this application, patterning the
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lead frame results in conductive trace elements within the support layer 16 of the acoustic
transducer.
[0020]
Referring to FIG. 3, a first type of lead frame, referred to as trace lead frame 20, is shown. The
trace leadframe 20 is generally rectangular in shape, comprising an outer frame member 28 and
a plurality of conductive traces extending in parallel across the width of the trace leadframe. The
conductive traces 22 are separated by slots 23 etched in the leadframe material and terminate in
end points 24, 26 on either side of the outer frame member 28. The trace lead frame 20 has a
plurality of alignment holes 32 at each of the four corners of the outer frame member 28. As
discussed further below, the width of the conductive trace 22 and the spacing between adjacent
traces of the conductive trace can be selected to provide a desired transducer array size.
[0021]
Referring to FIG. 4, a second type of lead frame, referred to as spacer lead frame 30, is shown.
The spacer lead frame 30, like the trace lead frame 20, is rectangular and comprises an outer
frame member 28 and an alignment hole 32. However, instead of the conductive traces 22, the
second type of spacer lead frame 30 comprises an open space 35 bounded by the inner edge 34
of the outer frame member 28. The use of the spacer leadframe 30 determines the width of the
space between the conductive traces 22 of adjacent trace leadframes of the trace leadframe 20,
as described further below.
[0022]
Referring to FIG. 5, a third type of leadframe called end leadframe 40 is shown. The end lead
frame 40 is rectangular as in the case of the trace lead frame 20 and the spacer lead frame 30
and has alignment holes 32. Unlike the leading leadframe, the interior 36 of the end leadframe
40 is completely solid and the openings are not etched. The end lead frame 40 further forms an
end member of the support layer 16 as described later.
[0023]
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Each of these three types of leadframes is formed from a thin metal sheet, eg, of BeCu, by a
conventional etching process. First, a photoresist material is applied to a sheet of leadframe
material. The photoresist material is then subjected to imaging of the pattern representing the
lead frame. Next, each lead frame is immersed in an etching solution, such as ferric chloride or
sodium persulfate. The slots 23 formed between adjacent ones of the conductive traces 22 are
opened by the etching process. The remaining etched leadframe material is then passivated, for
example, by electroplating a CrAu layer on the etched leadframe.
[0024]
As shown in FIG. 6, a single sheet 50 of BeCu material can be used to fabricate multiple
leadframes simultaneously. The sheet 50 includes twenty-five individual trace lead frames 20
suspended within the outer frame 52 using common support tabs 54 as shown. The support tab
54 also acts as a common electrode for passivation electroplating. Once the passivation step is
complete, the individual trace leadframes 20 are separated from the sheet 50 for use in the
fabrication of the support layer 16. This process is similarly repeated for the fabrication of the
spacer leadframe 30 and the end leadframe 40. Of course, it is possible to produce a large
number of leadframes by repeating this process.
[0025]
The finished leadframes are then assembled together in stack fixture 60, as shown in FIGS. The
stack fixture 60 comprises a rectangular base plate 56 supporting a central support 66 in
contact with the respective bottom stack plate 62 extending from the center of the base plate
towards the corners of the base plate . The stack plate 62 mechanically connects to the
expansion screw 64. As shown, there are four alignment pins 58 corresponding to four stack
plates 62 and four alignment holes 32 in each of the three types of leadframes. Rotation of the
expansion screw 64 causes the associated stack plate 62 to move radially outward with the
associated alignment pin 58.
[0026]
The lead frames are stacked relative to the stack fixture 60 such that the alignment pins 58
engage the respective alignment holes 32 of the lead frame. First, the end lead frame 40 is
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attached to the stack fixture 60 above the stack plate 62, followed by the spacer lead frame 30.
Next, the trace lead frame 20 is mounted on the spacer lead frame 30, and another spacer lead
frame 30 is mounted on the trace lead frame. Additional trace leadframes and spacer leadframes
are stacked to the stack fixture 60 in a similar manner until the desired number of layers are
obtained. The trace leadframes 20 are arranged such that the conductive traces 22 of the
respective leadframes are parallel to one another. Next, when the expansion screw 64 is rotated,
the alignment pin 58 moves outward, and the lead frame is pulled laterally, so that the flatness of
the lead frame is secured. In fact, only three out of the four expansion screws need to be adjusted
to provide the necessary tension on the lead frame.
[0027]
Referring to FIG. 7, a cross section of a typical leadframe stack for forming the support layer of a
3 × 2 transducer array is shown. The stack includes end leadframes 40 at both the bottom and
top of the stack. Between the end leadframes 40, spacer leadframes 30 and trace leadframes 20
are alternately arranged. The trace leadframes 20 each comprise three conductive traces 22. The
outer frame members 28 of the trace leadframe 20 and the spacer leadframe 30 are aligned.
[0028]
In general, the thickness of each trace leadframe is less than or equal to a quarter wavelength (λ
/ 4) of the operating frequency of interest. The combination of the trace lead frame 20 and the
spacer lead frame 30 forms the same λ / 2 pitch, which is typical for piezoelectric elements in a
two-dimensional λ / 2 sample array. The spacer leadframe 30 prevents adjacent leadframes of
the trace leadframe 20 from shorting each other. As long as the total width of the trace lead
frame and the spacer lead frame is equal to the pitch of the piezoelectric element, the relative
thicknesses of the trace lead frame 20 and the spacer lead frame 30 may be the same or
different. I do not mind.
[0029]
That is, it may be desirable to minimize perturbation of the conductive trace 22 in the transducer
by using a trace leadframe 20 that is thinner than the spacer leadframe 30. For example, FIG. 2
shows a two dimensional array element with different azimuthal and elevational dimensions, with
the spacer leadframe 30 being thicker than the trace leadframe 20. It is also possible to further
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increase the spacing between the conductive traces 22 by using a plurality of spacer leadframes
30 between each trace leadframe.
[0030]
Once the desired number of leadframes are stacked on the stack fixture 60, an electrically
insulating support material is injected into the stack, as shown in FIG. The liquefied support
material penetrates the entire stack and fills all spaces located between adjacent conductive
traces 22 and the open spaces 35 of the spacer lead frame 30. The support material is expected
to be composed of a sound absorbing material such as tungsten, silica or chloroprene and an
acoustic diffusing material, but other materials with similar sound absorbing properties can be
used effectively is there.
[0031]
After pouring the support material, the liquefied support material is cured by applying heat and
pressure to the infiltrated leadframe stack to form a rough support layer structure. The stack is
placed in a vacuum oven for a predetermined period of time (about 10 minutes) and venting of
the support material is applied to pull out any unwanted air bubbles that may have inadvertently
remained in the structure. Next, as shown in FIG. 10, by stacking the upper stack plate 68 on top
of the stack, it is possible to apply a pressure load to the stack. The upper stack plate 68 allows
for even distribution of pressure load to the infiltrated stack. With the proper pressure load
(about 50 psi) applied, the stack is placed in an oven and the support material is baked (about 12
hours at 50 ° C.) to a solid structure. As will be apparent to those skilled in the art, the values of
time, pressure and temperature depend, in part, on the material selected, the desired operating
characteristics of the support layer, and the array size selected. It is also possible to make
effective use of the value of. Once the heating and pressing steps are complete, the permeation
stack is removed from the oven and allowed to cool. The solid structure is then obtained by
curing the support material.
[0032]
The lead frame can also be stacked on a stack fixture 60 combined with insulating crossreinforcement members 74 disposed vertically to the conductive traces 22, as shown in FIG. The
insulating cross-reinforcement member 74 prevents the middle portion of the conductive trace
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22 from sag despite the tensile force applied by the alignment pin 58. The insulating crossreinforcement members 74 are constructed of an electrically insulating material to prevent
conduction between adjacent conductive traces 22. The liquefied support material is then poured
into the stack with the insulation cross-reinforcement members 74 in place. Alternatively, the
trace lead frame 20 can be provided with an insulating coating to further block unwanted
electrical conduction.
[0033]
Next, the cooled and solidified support layer structure shown at 70 in FIG. 11 is removed from
the stack fixture 60 and machined to a final shape. Grinding and flattening the upper surface 72
ensures good bonding with the piezoelectric layer 14. The side edges of the support structure 70,
including the outer frame members 28 of the individual leadframes, are also removed to obtain
the final shape shown in FIG. The resulting structure extends longitudinally, but otherwise
comprises separate conductive traces 22 from one another. In addition, the insulating coating
formed by the support material remains on the entire outer surface of the support structure 70.
FIG. 14 shows the structure of the completed support layer 16 with the conductive traces 22
embedded therein.
[0034]
Once the machining step is complete, it is possible to bond the piezoelectric layer 14 and the
matching layer 12 to the top surface 72 of the support layer 16. By dicing on the piezoelectric
layer 14, the matching layer 12, and the support layer 16 using a dicing saw, as shown in FIG.
15, independent piezoelectric conversion elements are formed. The independent transducer
elements are each electrically connected to the associated one of the conductive traces 22 and
are acoustically separated from the adjacent transducer elements by the score lines 78 formed by
the dicing saw.
[0035]
Alternatively, as shown in the side view of FIG. 13, the upper surface 72 is machined to leave a
portion of the outer frame member 28 intact and to have a self-aligned structure with the
piezoelectric layer 14 It is also possible to make it obtainable. The outer frame members 28 are
in physical contact with each other, and thus are electrically connected to each other. Once the
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piezoelectric layer 14 and the matching layer 12 are bonded, they are diced through the
remainder of the outer frame member 28 and into the support layer. This ensures good electrical
connection between the conductive traces 22 and the piezoelectric layer 14 and eliminates the
need for perfect alignment of the dicing saw with the embedded conductive traces.
[0036]
In another embodiment of the present invention, the conductive trace 22 is extended outward
from the end of the support layer to form a tab electrically connectable to an external circuit
element such as a circuit board. Is possible. After the lead frame is stacked on the stack fixture
60, the liquefied support material is poured into the stack, with the stack sideways, as shown in
FIG. The support material does not completely cover the stack, but rather the end of the stack
will protrude from the surface of the support material (shown by the imaginary lines at 75). The
backing layer is machined when cured, as described above, leaving the tabs 76 when the outer
frame members 28 of the stack's protrusions are removed. As shown in FIG. 17, the piezoelectric
layer 14 and the matching layer 12 are bonded to the end of the support layer 16 opposite to the
protruding tab 76, and dicing is performed on these layers as described above. Individual
conversion elements are formed. Tabs 76 allow electrical connection of conductive traces 22 to
the individual transducer elements.
[0037]
In the case of an acoustic transducer that is larger than the cross-sectional area of the embedded
conductive trace 22, the presence of the conductive trace minimizes perturbations in the acoustic
support environment of the transducer. However, as the transducer elements become smaller, it
may be necessary to reduce the cross-sectional area of the conductive trace at the end of the
trace near the lower surface 15 of the piezoelectric layer 14.
[0038]
Referring to FIGS. 18-24, an alternate embodiment of the reduced cross-sectional conductive
trace 22 is disclosed. FIGS. 18 and 19 show the conductive traces 22 tapered to a narrow portion
82 connected with the frame member 28. The tapered portion 84 of the conductive trace 22 will
be located between the normal width portion and the narrow portion 82. By etching the BeCu
core frame material with a modified pattern, an alternative trace lead frame 20 is manufactured
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in a manner similar to that described above.
[0039]
Modifications can be made to the lead frame to provide a narrowing in more than one dimension.
In FIG. 20, conductive traces 22 having tapered portions are shown in both the lead frame width
dimension 86 and the thickness dimension 88. As known in the art, the thickness 88 can be
narrowed by controlling the timing of the imaging and etchant. An example of a conductive trace
22 that is narrowed to form a cross-shaped portion 92 is shown in FIG.
[0040]
In another alternative geometry of conductive trace 22, the contact area of the trace is reduced
and this contact area is removed from the center of the piezoelectric element. As shown in FIGS.
22 and 23, each conductive trace forms a smaller substrate 94, 96 placed back to the
piezoelectric element at the outer edge of the piezoelectric element where acoustic displacement
and energy density are lowest. As patterned.
[0041]
In FIG. 24, conductive traces 22 are tapered in width over the entire length of the traces. The
narrowest portion 102 of the width is located at the end of the conductive trace 22 in contact
with the piezoelectric element. The first tapered portion 104 is thicker from the narrowest
portion 102 to the intermediate width portion 106. The second tapered portion 108 further
increases in width from the intermediate width portion 106 to the full width portion 110. Of
course, it is also possible to effectively change the rate at which the width of the conductive trace
22 changes from the first end to the second end by using more or less tapered portions. is there.
It will also be appreciated that the conductive traces 22 can be tapered not only in the width
dimension but also in the thickness dimension, as described above with respect to FIGS.
[0042]
Finally, FIG. 25 shows an alternative embodiment of a trace lead frame 20 which utilizes pitch
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expansion, also referred to as "dimensional fan out". In this embodiment, the spacing between the
individual conductive traces 22 is such that one end of the trace is wider than the other. The
narrower spacing at one end is intended to match the pitch of the individual piezoelectric
transducers, while the wider spacing at the other end facilitates connection to circuit elements. In
order to The conductive traces can include centrally located traces 112 extending directly across
the lead frame and angled traces 114, 116 that vary in degree of offset relative to the centrally
located traces. The dimensional fan-out can be evenly spaced across the width of the leadframe,
as shown in Figure 25, or it can be offset to the left or right of the leadframe with independent
conductive traces It is.
[0043]
While the preferred embodiments of the support layer for an acoustic transducer utilizing an
etched lead frame have been described above, it will be apparent to those skilled in the art that
there are several embodiments within the scope of this device. An advantage was obtained. The
invention is further defined in the claims.
[0044]
While the embodiments of the present invention have been described in detail, in order to
facilitate the understanding of the embodiments, they are summarized below and listed below.
[0045]
【0045】1.
A method for manufacturing a support layer (16) for use in an acoustic transducer (10)
comprising a plurality of transducer elements (18) aligned in a matrix, each comprising an outer
frame member 28) providing a plurality of leadframes (20), and conductors (22) extending
across the leadframes, each end of the outer frame member being terminated, and the plurality of
leadframes (20) Stacking the respective conductors (22) in adjacent leadframes of the leadframe
to a position where a space is formed between the respective conductors; and Pouring the
electrically insulating sound absorbing support material to completely fill the space between the
conductors; It is, from a plurality of lead frames poured sound absorbing support material
consists of removing the outer frame member (28) and the excess absorbing support material, an
acoustic transducer supporting layer manufacturing method.
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[0046]
【0046】2. In the step of providing the plurality of lead frames (20), a step of applying a
photoresist material to the sheet (50) of lead frame material, and a trace including the plurality of
lead frames (20) in the photoresist material • imaging the pattern, selectively etching the sheet
(50) of leadframe material, passivating the etched leadframe material, and individually bonding
the leadframes It is a manufacturing method of a support layer (16) for acoustic transducers
given in the above-mentioned 1 characterized by including the step of separating.
[0047]
【0047】3. The pouring step further comprises evacuating the stacked and poured lead
materials (20) for a first period of time; and the stacked and poured support materials. Loading a
predetermined amount of pressure on the lead frame (20) and heating the plurality of stacked
lead frame (20) poured support material to a predetermined temperature for a second period of
time; It is a manufacturing method of the support layer (16) for acoustic transducers as described
in said 1 or 2 characterized by including.
[0048]
【0048】4. The removing step is further characterized by the step of grinding the edges of
the stacked lead material (20) poured the support material to obtain desired dimensions and
flatness. It is a manufacturing method of the support layer (16) for acoustic transducers as
described in said 1 to 3.
[0049]
【0049】5. The stacking step further comprises stretching the plurality of leadframes by
applying an outward force to the corners of the outer frame member (28) as described in the
preceding 1-4. The acoustic transducer supporting layer (16) of
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[0050]
【0050】6. The acoustic transducer as described in any one of 1 to 5, wherein the step of
stacking further includes the step of inserting an insulation cross reinforcing member (74) in the
space perpendicular to the conductor (22). It is a manufacturing method of a support layer (16).
[0051]
【0051】7. An array of transducer elements (18) with front and back faces (13, 15) and a
plurality of conductors (22) of lead frame material coupled to the back face (15) of the
transducer elements (18) The first end (24) of the conductor is coupled to each of the conversion
elements and the second end (26) of the conductor is the support An acoustic transducer (10),
characterized in that the support layer is located on the side facing the conversion element of the
layer, and the support layer has an acoustic impedance which attenuates the acoustic energy
from the back side.
[0052]
【0052】8. In the plurality of conductors (22), the spacing formed therebetween is equal
to the pitch between adjacent ones of the conversion elements (18) at the first end (24); The
acoustic transducer according to claim 7, characterized in that it is significantly different at the
end (26) of the two.
[0053]
【0053】9. The acoustic transducer according to 7 or 8, wherein the conductor (22)
further has a tapered cross section over the entire length thereof.
[0054]
【0054】10. 7. The acoustic transducer according to 7, 8 or 9, wherein the conductor
(22) further includes a cross-sectional portion in which the first end is narrowed.
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[0055]
As described above, according to the present invention, when forming the support layer of the
acoustic transducer in which the transducer elements are arranged in a matrix, the plurality of
lead frames having the outer frame members are crossed. An extending conductor is provided to
stack the lead frames, forming spaces respectively between the conductors of adjacent lead
frames, and filling the space between the conductors with an electrically insulating sound
absorbing support material, and an outer frame member Since the excessive sound absorbing
support member is removed, the internal reflection of the acoustic energy can be prevented from
returning to the converting element while the sound energy output from the back of the
converting element is sufficiently attenuated, and the supporting layer is converted to acoustic
Electrical interconnections between the array and the corresponding contacts of the electrical
circuit element are possible, yet cost can be reduced and a large number of relatively narrow
piezoelectrics It can be easily applied to a large transducer array of the child.
[0056]
Brief description of the drawings
[0057]
1 is a perspective view of an acoustic transducer array.
[0058]
2 is a top cross-sectional view of the acoustic transducer array, taken at line 2-2 of FIG. 1;
[0059]
3 is a plan view showing a patterned lead frame comprising a plurality of conductive trace
elements.
[0060]
4 is a plan view showing a patterned lead frame provided with a spacer element.
[0061]
5 is a plan view showing a patterned lead frame comprising the end element.
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[0062]
6 is a plan view showing a single substrate including a plurality of patterned lead frames.
[0063]
7 is a cross-sectional plan view of a stack of patterned lead frames.
[0064]
8 is a cross-sectional view showing a stack of lead frames attached to the assembly fixture.
[0065]
9 is a plan view of the assembly fixture.
[0066]
FIG. 10 is a cross-sectional view showing the stack of lead frames attached to the assembly
fixture upon curing of the sound attenuating material.
[0067]
11 is a cross-sectional plan view of the cured support layer assembly.
[0068]
12 is a cross-sectional side view of a cured support layer assembly comprising an insulating
spacer bar.
[0069]
FIG. 13 is a cross-sectional side view of a cured support layer aligned to attach a piezoelectric
transducer layer.
[0070]
14 is an isometric view of a plurality of conductors disposed in the support layer.
[0071]
13-04-2019
18
15 is a cross-sectional side view of the completed support layer with the piezoelectric element
and the matching layer attached thereto.
[0072]
FIG. 16 is a perspective view of an alternative embodiment of a support layer in which the
conductive elements of the lead frame extend outside the sound attenuating material.
[0073]
FIG. 17 is a cross-sectional side view of an alternative embodiment of a support layer showing
the conductors extending to the outside of the sound attenuating material.
[0074]
18 is a plan view showing the main part of an alternative embodiment of a lead frame with a
narrowed end.
[0075]
FIG. 19 is a cross-sectional end view of the alternative lead frame taken on line 19-19 of FIG. 18;
[0076]
FIG. 20 is a cross-sectional end view of a second alternative lead frame taken cut along line 1919 of FIG. 18;
[0077]
FIG. 21 is a cross-sectional end view of the third alternative lead frame taken on line 19-19 of
FIG.
[0078]
FIG. 22 is a plan view showing the main part of a fourth alternative embodiment of the lead
frame.
[0079]
FIG. 23 is a cross-sectional end view of a fourth alternative embodiment of a lead frame taken cut
along line 23-23 of FIG.
13-04-2019
19
[0080]
FIG. 24 is a plan view of a fifth alternative embodiment of a lead frame with a tapered cross
section.
[0081]
FIG. 25 is a plan view of a sixth alternative embodiment of the lead frame with enlarged pitch.
[0082]
Explanation of sign
[0083]
REFERENCE SIGNS LIST 5 sound wave 10 acoustic transducer phased array 12 matching layer
13, 72 upper plane 14 piezoelectric layer 15 lower plane 16 support layer 18 piezoelectric
element 20 trace lead frame 22 conductive trace 23 slot 28 outer frame member 30 spacer lead
frame 32 Alignment hole 34 Inner edge 35 Open space 40 End lead frame 50 Sheet 52 External
frame 54 Support tab 56 Base plate 58 Alignment plate 60 Stack fixture 62 Stack plate 64
Expansion screw 66 Center support 68 Top stack Plate 70 Support layer structure 72 Upper
surface 74 Insulated cross reinforcing member 76 Tab 78 Groin 92 Cross shaped portion 94, 96
Substrate 102 Narrowest portion 104 width First tapered portion 106 Medium width portion
Minute 108 second tapered portion 112 central trace 114, 116 angled trace
13-04-2019
20
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