DE102022123306A1 - Method for producing a curved circuit carrier and curved circuit carriers - Google Patents

Abstract

The invention relates to a method for producing a curved electronic circuit carrier (1) and a curved circuit carrier, in particular an ultrasound sensor device or an ultrasound catheter, wherein the circuit carrier (1) comprises a substrate (2) with conductor tracks (3) which form a The top of the substrate (2) has exposed substrate pads (4). In order to enable particularly simple production and at the same time precise positioning and orientation of the electronic components arranged on the curved circuit carrier, a reinforcing layer (5) is attached to an underside of the substrate (2), at least one slot (6a; 6b) in which reinforcing layer (5) is introduced and the substrate (2) is curved along the slot (6a; 6b).

Description

The invention relates to a method for producing a curved electronic circuit carrier, in particular for an ultrasound sensor device or an ultrasound catheter, according to the preamble of claim 1 and to a curved electronic circuit carrier.

Curved electronic circuit carriers are known through use, which comprise a substrate with conductor tracks. The conductor tracks have exposed contact points on an upper side of the substrate, which are electrically conductively connected to electronic components. Due to the curvature of the electronic circuit carrier, the electronic components can each be arranged at an angle to one another and spaced apart from one another in the circumferential direction.

The object of the invention is to provide a method for producing a curved electronic circuit carrier, which enables particularly simple production and at the same time precise positioning and orientation of the electronic components arranged thereon, such as ultrasonic sensors.

This object is achieved in that a reinforcing layer is attached to an underside of the substrate, at least one slot is made in the reinforcing layer and the substrate is curved along the slot. Due to the design of the slot, the axis of curvature and the angle can be specified exactly, so that even after the curvature, the electronic components on the curved circuit carrier have a defined mutual position and orientation.

In an advantageous embodiment, the substrate can be curved in such a way that the opposite walls of the slot rest against one another. Since the intermediate angle of the opposite walls can be set exactly when producing the slot, the angle of the curvature in the event of a curvature until the opposite walls of the slot rest against each other is also precisely specified and easily reproducible.

The at least one slot can advantageously have a triangular or trapezoidal cross-section, in particular a cross-section in the form of an isosceles trapezoid. This enables a relatively large mutual contact surface of the opposite walls of the slot after the curvature of the circuit carrier. The large contact surface prevents elastic deformation in the curved state due to the low surface pressure, which also supports precise mutual positioning and orientation of electronic components on the circuit carrier. In the event that the opposite walls of the slot are glued together after the electronic circuit carrier has been curved, the adhesive forces are also relatively large due to the large contact surfaces.

In a particularly advantageous embodiment, several, in particular parallel, slots can be made in the substrate. Each slot enables curvature around a separate axis of rotation/curvature, so that any desired course of the curvature of the electronic circuit carrier can be set. By means of several parallel, evenly spaced slots, a part-circle or circular curvature can be produced in cross section corresponding to a cylinder jacket or cylindrical. In the event that the course of the slots has an angle to one another, the electronic circuit carrier can also be curved, for example, in the form of a cone.

The angle β between opposing walls of a slot (intermediate angle) is preferably selected depending on the number a of slots and the angular range γ which the curved circuit carrier should have/spann, whereby the formula for the intermediate angle can be: β =γ/a. This applies preferably to parallel slots. If, for example, ten parallel slots are provided in an electronic circuit carrier, which are preferably at the same distance from one another, a closed cylinder jacket-like shape of the curved electronic circuit carrier, which corresponds to an angular range γ = 360 °, can be achieved if β applies to the intermediate angle of each slot = 360° / 10 = 36°. The formula mentioned can also be used to determine the intermediate angles for other curvatures and/or angular ranges.

Particularly preferably, the slots can be made in the reinforcing layer and/or the substrate using a saw blade, in particular a circular saw blade, or a grinding wheel. The saw blade or the grinding wheel advantageously has a cutting edge or a grinding body on the outer circumference with a triangular or trapezoidal cross-section, in particular with a cross-section in the form of an isosceles trapezoid, which corresponds to the contour of the slot to be produced. This makes it possible to produce slots with the desired intermediate angles particularly easily and with repeatable accuracy. The side surfaces, which are arranged at an angle to one another in cross section The cutting edge or grinding wheel particularly preferably has an intermediate angle δ, which corresponds to the intermediate angle β of the slot or slots.

On the top side of the substrate, several electronic components or semiconductor components, in particular as flip chips using flip chip assembly or as semiconductor chips with top contacts, can be arranged and connected to the conductor tracks via the contact points. The assembly of the semiconductor components, which can in particular be ultrasound-generating structures or ultrasound sensors, can take place before or after the application of the reinforcing layer to the underside of the substrate or the introduction of the at least one slot.

In order to enable precise positioning of the semiconductor components, the semiconductor components can be arranged on the substrate in the form of a matrix, in particular in a rectangular pattern.

Furthermore, the electronic components or semiconductor components on the top side of the substrate can be underfilled and/or covered with a layer. The layer can be, for example, a curable resin or another plastic. Slots can then be made in the electronic components or the semiconductor components and possibly also in the layer and possibly also partially in the substrate on the top side, for example by means of a sawing process, the slots in the electronic components or semiconductor components preferably being opposite to the Slots are positioned in the reinforcing layer. In the cross section through the circuit carrier, the (symmetry) axes of a slot in the reinforcing layer on the underside of the substrate and of the opposite slot on the top of the substrate can be positioned aligned with one another. This enables a particularly high level of flexibility and thus easy curvature of the electronic circuit carrier.

For particularly precise positioning of electronic components or semiconductor components on the top side of the substrate and of the slots on the top and bottom sides of the substrate, at least two reference marks can be provided in the substrate, which preferably come from both the top side and the bottom side of the substrate are recognizable. The arrangement of the semiconductor components and the slots on the top and bottom of the substrate can be done depending on the reference marks, which makes positioning easier.

Furthermore, a curved electronic circuit carrier, in particular an ultrasound sensor device or an ultrasound catheter, is also claimed with a substrate comprising conductor tracks, the conductor tracks having exposed substrate pads/contact points on an upper side of the substrate. The circuit carrier is curved along several slots in a reinforcing layer on the underside of the substrate and possibly in the underside.

In the curved electronic circuit carrier, the opposing walls of each slot preferably abut one another, resulting in precise mutual positioning of the various sections of the circuit carrier. In addition, an ultrasound-generating structure or an ultrasound sensor or possibly several ultrasound sensors can advantageously be provided in the cross section on the top side of the substrate between two slots, which results in a particularly compact design.

• 1 einen Querschnitt durch einen Teil eines Schaltungsträgers in einem ersten Herstellungsschritt;
• 2 einen Querschnitt durch den Teil eines Schaltungsträgers von 1 in einem zweiten Herstellungsschritt;
• 3a-c eine Draufsicht, einen Querschnitt und eine Unteransicht auf den Schaltungsträger von 2;
• 4a eine erste Ausführungsform eines gekrümmten Schaltungsträgers;
• 4b eine zweite Ausführungsform eines gekrümmten Schaltungsträgers und
• 5 eine perspektivische Darstellung des gekrümmten Schaltungsträgers von 4a.

Further special features and advantages of the invention result from the following description of preferred exemplary embodiments based on the drawings. Show it:

• 1 a cross section through a part of a circuit carrier in a first manufacturing step;
• 2 a cross section through the part of a circuit carrier 1 in a second manufacturing step;
• 3a -c a top view, a cross section and a bottom view of the circuit board of 2 ;
• 4a a first embodiment of a curved circuit carrier;
• 4b a second embodiment of a curved circuit carrier and
• 5 a perspective view of the curved circuit carrier from 4a .

In 1 a cross section through a part of a circuit carrier 1 is shown in a first manufacturing step. The circuit carrier 1 comprises a substrate 2, which is designed as a flat plate and preferably consists of a plastic. In the substrate 2, conductor tracks 3 made of an electrically conductive material are arranged within a layer or several layers of the substrate 2, the conductor tracks 3 having substrate pads or an exposed metal layer on an upper side of the substrate, of which, for example the substrate pad 4 is numbered. The substrate pads 4 serve for the later electrical connection of contact points for electronic components arranged on the top of the substrate 2, as in relation to 2 will be described in more detail.

On an underside of the substrate 2, a reinforcing layer 5 was attached/laminated in a previous manufacturing step (not shown), the reinforcing layer 5 also preferably being formed from a plastic.

In the in 1 In the manufacturing step shown, straight slots 6a, 6b were introduced into the reinforcing layer 5 and partly also into the substrate 2. As can be seen from the illustration, the slots 6a, 6b have a cross section in the form of an isosceles trapezoid, which points in the direction of the substrate 2.

Like that 3a and 3c To be taken, the slots 6a, 6b run parallel to each other.

The slots 6a, 6b are preferably produced using a saw blade 7, shown here schematically in partial section, for example in the form of a circular saw blade. The saw blade 7 has, adjacent to the outer circumference, a cutting edge 8 with a cross section in the form of an isosceles trapezoid, the side surfaces of the cutting edge 8, which are arranged at an angle to one another, having an intermediate angle δ, which is an intermediate angle β between opposing walls 9a, 9b of the slot 6a corresponds. By selecting a saw blade 7 with a correspondingly designed cutting edge 8, slots 6a, 6b with the appropriate dimensions can be produced particularly easily and precisely. In an embodiment not shown, several saw blades can be provided, which are simultaneously moved relative to the circuit carrier 1 and thereby form the slots 6a, 6b by machining.

In 2 is a cross section through the part of the circuit carrier 1 of 1 shown in a further manufacturing step. Here, after the production of the slots 6a, 6b, contact points 10 for electronic components 11 were arranged on the top of the substrate 2 and connected to the substrate pads 4 in an electrically conductive manner. The electronic components 11 can in particular be designed as semiconductor components such as chips and advantageously conductively connected to the contact points 10 by means of flip-chip mounting. The electronic components 11 can be applied to the planar substrate 2 via one or more flip-chip matrices, in particular in a rectangular pattern, whereby the electronic contact of the electronic components can be implemented, for example, via soldering, gluing or sintering. The electronic components 11 are then filled with a layer 15, for example made of plastic (for example epoxy resin). In a subsequent manufacturing step, slots 12a, 12b are introduced, for example by a sawing process, in the electronic components 11 (e.g. semiconductor chips), the layer 15 and partly in the substrate 2, the slots 12a, 12b being positioned opposite the slots 6a, 6b, as can be seen from the identical symmetry axes shown in dashed lines. The circuit carrier 1 is divided into several sections 13a, 13b, 13c by the slots 12a, 12b, 6a, 6b. The sections 13a, 13b, 13c are each designed to be dimensionally stable due to the reinforcing layer 5 and the layer 15 or the electronic components 11. The tapering of the cross section due to the slots 6a, 6b, 12a, 12b points the connection of the sections 13a , 13b, 13c however has a higher elasticity, which means that the in the 4a , 4b and 5 shown curvature of the circuit carrier 1 is facilitated.

In the 3a , 3b and 3c is the circuit carrier 1 of 2 shown in further views. As can be seen there, three reference marks 14a, 14b, 14c are provided in the substrate 2 in the form of through holes, so that the reference marks 14a, 14b, 14c both from the in 3a shown top as well as the in 3c shown underside of the substrate 2 can be seen. With the help of the reference marks 14a, 14b, 14c, the positioning of the electronic components 11, not shown here, as well as the slots 6a, 6b on the underside of the substrate 2 and the slots 12a, 12b on the top of the substrate 2 can be carried out particularly easily and yet precisely. The reference marks 14a, 14b, 14c allow the substrate 2 to be clamped and re-clamped precisely, with both the positioning of the electronic components 11, in particular in the form of a matrix or a rectangular pattern, and the introduction of the slots 6a, 6b within one clamping , 12a, 12b can be done.

In 4a a first embodiment of a curved circuit carrier 1' is shown. Here, the sections of the circuit carrier 1 'separated by slots, of which the sections 13a, 13b, 13c are marked here, were curved/rolled up to the mutual contact of the walls of each slot on the underside of the substrate 2 and fixed to one another, for example by means of gluing, whereby the circular cross section shown results. The angle β of the slots on the underside of the substrate 2, of which the slots 6a, 6b are numbered here, was dependent on the number a of slots and the angular range γ, which the curved scarf The cable carrier should have 1 `, calculated according to the formula for the intermediate angle β = γ / a. For a circular cross section, the angular range is γ = 360°. The number a of slots can depend on the number of electronic components or chips that are to be arranged on the curved circuit carrier 1 in a distributed manner in the circumferential direction. For example, an electronic component or chip can be provided on each section between the slots in the circumferential direction. In the exemplary embodiment shown, ten chips should be arranged distributed in the circumferential direction, so that the number a of slots is also equal to 10. Consequently, the intermediate angle β has a value of β = 360°/10 = 36°.

In 4b an alternative embodiment of a curved circuit carrier 1" is shown. In contrast to the embodiment of 4a In the cross section, only a partial circle with an angular range γ = 180° is spanned, whereby due to the number of a = 5 slots (4 full slots and 2 half slots), an intermediate angle β = 180° / 5 = 36° also results.

In 5 is a perspective view of the curved circuit carrier 1' of 4a shown in a partial area. As can be seen from the illustration, in this embodiment the electronic components not numbered here are arranged in a ring, with further annular sections with separate electronic components being able to follow in the longitudinal direction of the cylindrical arrangement of the circuit carrier 1 ', of which here are sections 13a' and 13b ' are quantified. As a result, not only can electronic components be arranged in the circumferential direction with a defined position and orientation relative to one another, but additional electronic components can also be positioned precisely in a ring shape in the longitudinal direction. Due to the arrangement of the electronic components on the planar substrate 2 in a matrix or in a rectangular pattern and the defined curvature due to the slots 6a, 6b, 12a, 12b, the electronic components are arranged very precisely in the form of a cylinder jacket. Such a configuration is particularly advantageous if an ultrasonic sensor or possibly several ultrasonic sensors are used as electronic components for each section of the circuit carrier, so that a particularly precise and small ultrasound catheter can be formed.

List of reference symbols:

1, 1', 1''

Circuit carrier

2

Substrate

3

pathway

4

Substrate pad

5

reinforcing position

6a, 6b

Slots in reinforcing layer 5

7

saw blade

8th

Cut

9a, 9b

Walls of the slot 6a

10

Contact points

11

Electronic component

12a, 12b

Slots in electronic components 11

13a, 13b, 13c, 13a', 13b'

Sections of the circuit carrier 1', 1''

14a, 14b, 14c

Reference marks

15

layer

β

Intermediate angle of the slots 6a, 6b

δ

Intermediate angle of the cutting edge 8

γ

Angle range

a

Number of slots in the circumferential direction

Claims (15)

Method for producing a curved electronic circuit carrier (1; 1';1''), in particular for an ultrasound sensor device or an ultrasound catheter, wherein the circuit carrier (1; 1';1") has a substrate (2) with conductor tracks (3 ), which have substrate pads (4) exposed to an upper side of the substrate (2), characterized in that a reinforcing layer (5) is attached to an underside of the substrate (2), at least one slot (6a; 6b) is introduced into the reinforcing layer (5) and the substrate (2) is curved along the slot (6a; 6b). Procedure according to Claim 1 , characterized in that the substrate (2) is curved in such a way that the opposing walls (9a; 9b) of the slot (6a) lie against one another. Procedure according to Claim 1 or 2 , characterized in that the at least one slot (6a; 6b) has a triangular or trapezoidal cross-section, in particular a cross-section in the form of an isosceles trapezoid. Procedure according to one of the Claims 1 until 3 , characterized in that several, in particular parallel, slots (6a; 6b) are introduced into the reinforcing layer (5). Procedure according to one of the Claims 1 until 4 characterized in that the angle β between opposing walls (9a; 9b) of a slot (6a; 6b) is selected depending on the number a of slots (6a; 6b) and the angular range γ which the curved circuit carrier (1; 1';1'') should have, according to the formula for the intermediate angle β = γ / a. Procedure according to one of the Claims 1 until 5 characterized in that the slots (6a; 6b) are made via a saw blade (7) or a grinding wheel in the reinforcing layer (5) and/or in the substrate (2), the saw blade (7) or the grinding wheel preferably has a cutting edge (8) or an abrasive body with a triangular or trapezoidal cross-section, in particular with a cross-section in the form of an isosceles trapezoid, adjacent to the outer circumference. Procedure according to Claim 6 , characterized in that the side surfaces of the cutting edge (8) or the grinding wheel, which are arranged at an angle to one another in cross section, have an intermediate angle δ, which corresponds to the intermediate angle β of the slot (6a). Method according to one of the preceding claims, characterized in that a plurality of semiconductor components (11), in particular by means of flip-chip assembly or as semiconductor chips with top contacts, are arranged on the top side of the substrate (2) and are connected via contact points (10) of the semiconductor components (11). be connected to the substrate pads (4) of the conductor tracks (3). Procedure according to Claim 8 , characterized in that the semiconductor components (11) are arranged on the substrate (2) in the form of a matrix, in particular in a rectangular pattern. Procedure according to Claim 8 or 9 , characterized in that the semiconductor components (11) comprise ultrasound-generating structures. Procedure according to one of the Claims 8 until 10 , characterized in that the semiconductor components (11) are underfilled and/or covered with a layer (15) and/or slots (12a; 12b) are introduced into the semiconductor components (11) and possibly into the layer (15), whereby the slots (12a; 12b) in the holding conductor components (11) or the layer (15) are preferably positioned opposite the slots (6a; 6b) in the reinforcing layer (5). Method according to one of the preceding claims, characterized in that at least two reference marks (14a; 14b; 14c) are provided in the substrate (2), which are preferably recognizable from both the top and bottom of the substrate (2), and the Positioning of the semiconductor components (11), the slots (12a; 12b) on the top of the substrate (2) and/or the slots (6a, 6b) on the bottom of the substrate (2) depending on the reference marks (14a; 14b; 14c) takes place. Curved electronic circuit carrier (1; 1';1''), in particular an ultrasound sensor device or ultrasound catheter, with a substrate (2) comprising conductor tracks (3), the conductor tracks (3) being exposed to an upper side of the substrate (2). Have substrate pads (4), characterized in that the circuit carrier (1; 1';1'') is curved along a plurality of slots (6a; 6b) in a reinforcing layer (5) on the underside of the substrate (2). Circuit carrier (1; 1';1'') according to Claim 13 , characterized in that the opposite walls (9a; 9b) of each slot (6a; 6b) in the underside of the substrate (2) abut one another. Circuit carrier (1; 1';1'') according to Claim 14 , characterized in that an ultrasonic sensor is provided in cross section on the top side of the substrate (2) between two slots (12a; 12b).

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