Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/18—Printed circuits structurally associated with non-printed electric components
  • H05K1/189—Printed circuits structurally associated with non-printed electric components characterised by the use of flexible or folded printed circuits
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/46—Manufacturing multilayer circuits
  • H05K3/4688—Composite multilayer circuits, i.e. comprising insulating layers having different properties
  • H05K3/4691—Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/03—Conductive materials
  • H05K2201/0332—Structure of the conductor
  • H05K2201/0388—Other aspects of conductors
  • H05K2201/0394—Conductor crossing over a hole in the substrate or a gap between two separate substrate parts
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09009—Substrate related
  • H05K2201/09081—Tongue or tail integrated in planar structure, e.g. obtained by cutting from the planar structure
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09009—Substrate related
  • H05K2201/09109—Locally detached layers, e.g. in multilayer
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/30—Details of processes not otherwise provided for in H05K2203/01 - H05K2203/17
  • H05K2203/308—Sacrificial means, e.g. for temporarily filling a space for making a via or a cavity or for making rigid-flexible PCBs
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W90/00—Package configurations
  • H10W90/701—Package configurations characterised by the relative positions of pads or connectors relative to package parts
  • H10W90/721—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bump connectors
  • H10W90/724—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bump connectors between a chip and a stacked insulating package substrate, interposer or RDL
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49117—Conductor or circuit manufacturing
  • Y10T29/49124—On flat or curved insulated base, e.g., printed circuit, etc.
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24273—Structurally defined web or sheet [e.g., overall dimension, etc.] including aperture
  • Y10T428/24322—Composite web or sheet

Definitions

• a printed circuit board with a flexible region according to claim 1 is specified.
• a common problem in the manufacture of inherently rigid printed circuit boards is to realize flexible areas without compromising the robustness or integrity of the circuit board as a whole.
• An object of embodiments of the invention is to provide an inherently rigid circuit board having a flexible area.
• the PCB should also be easy and inexpensive to implement with only slightly modified standard processes of production of rigid circuit boards.
• One embodiment of the invention relates to a printed circuit board comprising a circuit carrier, a cover layer of a non-conductive material comprising an organic substance and arranged on the circuit carrier, a first metallization plane arranged on the cover layer, the first metallization plane being a flexible one Has area.
• flexible is to be understood as meaning that when force is applied perpendicularly to the force Printed circuit board at least 10 times the deflection of the surface is compared with the non-flexible areas of the circuit board. This condition is to be met at least for tensile forces, but advantageously for tensile and compressive forces.
• the flexible area can be located on a very small part of the board, which is relative to the entire area of the printed circuit board
• the material for the cover layer may include, for example, a resin as the organic substance.
• the cover layer in addition to the first metallization level, is also flexible in the flexible area.
• first metallization level can be mechanically stabilized by the cover layer.
• first metallization level in the layer thickness is formed very thin. It can then be so thin that it would be mechanically unstable on its own and the layer thickness in its minimum thickness is limited only by the function as an electrical conductor. The geometry of the first metallization is no longer by supporting this
• a material can be used which does not restrict the flexibility of the first metallization level and nevertheless contributes to the sufficient stability of the first metallization level.
• the flexible region has at least one axis along which it can be turned against the remaining printed circuit boards.
• the flexible area about this axis can be moved both toward and away from the remaining circuit board.
• Embodiments are also possible in which a movement of the flexible region only occurs or is made during operation of the printed circuit boards.
• the flexible region is connected to its surroundings or the remaining printed circuit board on only one side.
• the flexible area can then be formed, for example, as a tongue.
• the side on which the flexible area is connected to the environment may also have recesses. These can extend from and extend into the outer edges of the flexible area, creating corners. But they can also be recesses that do not extend to the outer edge, such as holes or slots in the flexible area. The recesses further increase the flexibility of the flexible area.
• the flexible area is arranged above a free space.
• free space is to be understood as meaning that the flexible area has no mechanical or chemical bonding to the plane that runs beneath it.
• the free space can thus be formed, for example, as a cavity into which the flexible area can be moved.
• Under free space is also to be understood that below the flexible area directly follows a plane or layer with the
• the flexible area thus has the possibility, even without a cavity under it, to be able to move out of the ladder level.
• materials which have a low adhesion tendency are particularly suitable for the layer below the flexible region. It can, for example, a Material can be used, which has fluorinated polymers.
• the first metallization level on the cover layer is formed in partial regions of the flexible region as a conductor track and / or contact surface.
• the first metallization level may be limited to a small portion of the flexible area.
• the first metallization level perceives the function of the power line or the electrical contact.
• the contact surface can serve, for example, for the electrical contacting of an electronic component, which is placed or mounted on the printed circuit boards.
• the flexible region is bent out of the plane of the printed circuit board before the electronic component is mounted, before the electronic component is placed on the contact surface.
• the flexible regions are pressed into the cavity which is located beneath them by the placement of the electronic component.
• embodiments are conceivable in which, after the assembly of the electronic component, the flexible regions are still in their initial position parallel to the printed circuit board, but their flexibility allows the attached electronic component a certain mobility.
• the flexible region has recesses which increase the flexibility of the flexible region. These recesses can lead into the flexible area both from the free edges and from the side with which the flexible area is connected to the surroundings. Likewise, recesses are also conceivable which start neither from a free side nor from the connected side of the flexible region, but are present as holes of different geometries in the flexible region. In this case, embodiments are conceivable in which the cover layer in the flexible region is reduced or even removed so far in thickness that it is present only in the partial regions where it is coated with the first metallization plane.
• the cover layer comprises a stabilizing tissue.
• This fabric may for example consist of individual free fibers as well as a mat.
• the material may be, for example, a fibrous tissue.
• the cover layer can have other reinforcing elements in addition to the stabilizing fabric or instead. These reinforcing elements can be incorporated in the layer itself as well as on the surface of the cover layer. The reinforcing elements can impart additional stiffness to the cover layer. In the application of the reinforcing elements, the region of the axis about which the flexible region can move can be recessed, or the reinforcing elements can be destroyed again in a further process step in the region of the axis.
• an electronic component is arranged on the flexible region, which is electrically connected to the first metallization level.
• the entire electronic component has a certain flexibility with respect to the printed circuit board. This flexibility can exist not only towards or away from the PCB, but in all three spatial directions.
• a circuit board may also have more than one flexible area. On a printed circuit board more than one component can also be arranged over one or more flexible regions.
• the compliance with tensile stress of the flexible region in the direction of the printed circuit board plane is increased by recesses.
• a cap is placed on the circuit board so that at least in some areas an enclosed volume for receiving a component is formed.
• the cap can cover only a part of the circuit board, but also the entire circuit board.
• the flexible area may be located inside or outside the cap.
• the circuit board can be used for example as an interposer. In this case, it can be arranged between a conventional circuit carrier not according to the invention and a stress-sensitive component which is preferably seated on the printed circuit board in the flexible region.
• a printed circuit board having a thermal expansion coefficient with respect to the circuit board plane that is at least 4 ppm / K greater than that of the electronic component mounted on the circuit board may be used.
• the thermal expansion coefficient of the printed circuit board may be greater than 12 ppm / K, and that of the electronic component mounted on the printed circuit board may be less than 8 ppm / K.
• the flexible area prevents unacceptably high thermal stress on the component.
• a method variant for producing a printed circuit board comprises the following method steps: provision of a circuit carrier, application of a delamination layer to a spatially limited subarea of the circuit carrier, application of a layer sequence to the delamination layer and a subregion of the circuit carrier, comprising a cover layer, which is an organic material and a first metallization level on the cap layer, and patterning the cap layer and the first metallization level defining a flexible region of the first metallization level.
• a partial region of the cover layer is at least partially detached from the remainder of the cover layer. This means that, for example, by cutting, milling or etching or other process techniques, a part of the cover layer is structured, which is no longer connected to all sides with the surrounding cover layer and so compared to the surrounding cover layer has increased flexibility. With the cover layer, the first metallization plane arranged on the cover layer also exhibits this flexibility. The flexible region thus defined can now be bent out of the plane of the cover layer, for example, in a further process step.
• the delamination layer is removed in a further method step to form the flexible region.
• a cavity can be created under the flexible region. This cavity allows the flexible area not only to move out of the circuit board plane, but also into the plane.
• the delamination layer can be applied and patterned as a sacrificial layer.
• the sacrificial layer may be selected from soluble
• Layers selectively etchable layers, volatile or decomposable layers, vaporizable layers, and low melting layers. This allows the sacrificial layer on the circuit board to be removed without affecting the adjacent layers.
• the method of the sacrificial layer makes it possible, on the one hand, to create very large open spaces and, on the other, to generate very thin and already flexible layers over the sacrificial layer.
• the thin layers can be stabilized and cured after their application to the sacrificial layer, so that they have sufficient stability after removal of the sacrificial layer. This can be done, for example, by generating or superposing several further thin layers.
• the printed circuit board can be produced by a production method which comprises the following method steps: providing a circuit carrier, working out a depression in the circuit carrier, applying a layer sequence to the circuit carrier so that the depression overlaps but not filling, thereby forming a free space, wherein the layer sequence comprises a cover layer comprising an organic material and a first metallization level on the cover layer, structuring the cover layer and the first metallization level over the clearance, such that a flexible region of the first Metallization is formed.
• This variant of the method has the advantage over the first method variant described that no delamination layer is necessary here.
• FIGS. 1 a to i schematically show the method step sequence of a method variant
• FIG. 2 is a schematic plan view of an embodiment
• FIG. 3 shows the top view of a further embodiment
• FIG. 4 shows the schematic side view of a possible special embodiment
• FIG. 5 shows the schematic side view of a further particular embodiment
• FIG. 6 shows a schematic side view of a possible further embodiment
• FIG. 7 shows a schematic side view of a possible further embodiment with additional elements
• FIGS. 8a and 8b show further embodiments, which additionally have a cap
• FIG. 9 shows a schematic side view of a possible further embodiment
• FIGS. 10a to 10c schematically show the method steps of a further production method
• FIGS. IIa to Hd schematically intermediate stages in a manufacturing process in the supervision.
• FIG. Ia the circuit carrier 1 is shown.
• a second metallization level 2 is arranged on the circuit substrate 1.
• the presentation of through-contacts or external connections on the top and / or bottom side of the circuit carrier has been dispensed with.
• the circuit carrier for example, a glass fiber reinforced epoxy substrate can be used.
• the second Metallization level can be used, for example, a copper foil.
• the copper foil can be laminated, for example, to the circuit carrier 1.
• the second metallization level 2 may already be structured before being applied to the circuit carrier 1 or after
• FIG. 1 b shows the layer sequence comprising the circuit carrier 1, the second metallization level 2 and the delamination layer 3.
• This layer sequence can emerge, for example, from the layer sequence illustrated in FIG. 1 a by applying the delamination layer 3 to the second metallization level 2.
• the delamination layer 3 still covers the entire second metallization plane 2.
• a preferred thickness for the delamination layer 3 is in the range of 1 to 50 ⁇ m.
• the material for the delamination layer 3 can be chosen so that it can be removed again in a further later method step.
• the following techniques may be used for removal, for example: dissolution, etching out, treatment with plasma, treatment with elevated temperatures, evaporation, sublimation, decomposition, swelling or foaming.
• soluble resists those resists which dissolve very well rather than dispersing or disintegrating into coarse particles or flakes are preferred. This simplifies the complete removal of the material of the delamination layer 3.
• paints are also particularly thermally low-residue or residue-decomposable polymers.
• Materials which can be removed with aqueous solvents are, for example, polyvinyl alcohol or polyvinylpyrrolidone.
• the temperature range for the thermal decomposition is preferably in the range of 180 to 260 ° C.
• the thermally decomposable material for example, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate and cellulose esters are suitable.
• the cellulose derivatives can also be removed by means of solvents. It is also particularly good materials whose melting points are in the range of 150 to 220 0 C.
• hexachloroethane should be mentioned, whose melting point is 186 0 C, but which already has a high sublimation at 185 0 C.
• Another possible material which can be used for the delamination layer 3 is Unity ® 2000P Sacrificial Polymer of Promeros LLC, Ohio.
• FIG. 1c schematically illustrates an exposure method by which the delamination layer 3 is to be structured.
• a mask 15 is applied over the delamination layer 3, whereby only a portion of the delamination layer 3 is hit by the radiation, which is schematically represented by the arrows.
• FIG. 1 d schematically shows the side view of the circuit carrier, which now has a structured delamination layer 3.
• the delamination layer 3 now only covers a portion of the second metallization level 2.
• the printed circuit board shown in FIG. Id can be accessed not only via the subtractive method shown in FIGS. 1b and 1c, but also alternatively via additive methods.
• the screen or stencil printing method or the application by inkjet should be mentioned.
• Non-photosensitive substances may also be used for the additive processes.
• a cover layer 4 is now applied over the free partial regions of the second metallization plane 2 and over the printed circuit board shown in FIG. 1e.
• Delamination layer 3 applied.
• the application can be done for example via lamination.
• the layer sequence cover layer 4 and first metallization level 5 can also be applied in two separate method steps.
• the cover layer 4, which comprises an organic material, for example, by casting, spin-coating or laminating are applied.
• the first metallization level 5 can then be applied to the cover layer 4. If the layer sequence cover layer 4 and the first metallization level 5 are to be applied in one process step, then, for example, a glass-fiber-reinforced epoxy base material may be used which has metallization on one side, which may be, for example, a thin copper foil.
• the first metallization level 5 preferably has a thickness in the range of 3 to 20 ⁇ m.
• the cover layer 4 preferably has a thickness in the Range of 5 to 100 microns.
• a resinous material can also be used for the cover layer 4, which can be provided with further reinforcement elements in or after the application process.
• a polyimide-based material is suitable, which may additionally have a Kupferkaschtechnik.
• FIG. 1 g shows a printed circuit board in which a small partial area of the first metallization level 5 has been removed. As a result of the removal, a small opening 20 a has formed in the first metallization plane 5, which is arranged above the delamination layer 3.
• the removal of the subarea of the first metallization plane 5 can be effected, for example, via a photostructuring step and a subsequent etching step.
• FIG. 1 h shows a printed circuit board in which the cover layer 4 located below the opening 20 a has been removed, so that a trench 20 b has been created.
• the trench 20b can, As shown in Figure Ih, extend into the delamination layer 3.
• an etching method may be used, such as a plasma etching method.
• the first metallization level 5 can serve as a mask.
• a laser may also be used to create the trench.
• the process steps illustrated in FIG. 1g and in FIG. 1h can also be carried out in a common process step.
• FIG. 11 shows a printed circuit board in which the delamination layer 3 has been removed so that a free space 7 has been created.
• the delamination layer 3 may be removed, for example, by leaching or etching out or by a thermal process. Depending on the technique used, the material of the delamination layer 3 can be swollen, foamed or decomposed. By removing the delamination layer 3, the flexible region 10 has been formed.
• Metalltechnischesebene 2 formed in the flexible portion 10 as a tongue 6.
• the circuit substrate 1 under the free space 7 is rigid, so not flexible.
• FIG. 2 shows a plan view of a printed circuit board.
• This circuit board could, for example, be one of those shown in FIG. Shown is the cover layer 4, on which the first metallization 5 is applied.
• the cover layer 4 and the first metallization level 5 comprise a flexible region 10.
• the flexible region 10 is bounded in a U-shape on three sides by the trench 20b.
• the first metallization 5 is here formed as a pair of conductor tracks, each terminating in a contact surface 9. After removal of the delamination layer 3, the flexibility of the region within the trench 20b is again significantly increased.
• the two contact surfaces 9 at the end of the first metallization 5 are flexible.
• the mechanical properties of the flexible region 10 are determined in this exemplary embodiment predominantly by the structure of the first metallization plane 5 and its thickness.
• a further flexibilization, in particular with respect to tensile and shear stresses in the plane, can be achieved by corresponding shaping of the conductor tracks of the first metallization plane 5, as shown in FIG.
• FIG. 3 shows a plan view of a further embodiment of the printed circuit board.
• the embodiment in FIG. 3 additionally comprises recesses 50.
• the trench 20b in FIG. 3 shows a plan view of a further embodiment of the printed circuit board.
• FIG. 2 surrounds the flexible region 10, it also serves to be able to dissolve out the delamination layer 3.
• the recesses in FIG. 3 additionally have the function of increasing the flexibility of the flexible region 10.
• the connections of the component to the printed circuit board are preferably carried out before removing the delamination layer 3, since these, as long as they still exist flexible area 10 stabilized.
• FIG. 4 shows a particular embodiment of the printed circuit board. The embodiment comprises a circuit carrier 1, a second metallization level 2, a cover layer 4, and a first metallization level 5. In this embodiment, no cover layer 4 is present in the flexible area 10.
• the flexible region 10 thus comprises only the first metallization level 5.
• the free space 7 is formed in this embodiment as a channel 35.
• the channel 35 can be filled via the inlet 25a with liquids or gases which can leave the channel 35 again via the outlet 25b.
• an electronic component 30 is arranged on the first metallization level 5.
• the channel 35 may be used, for example, to cool the electronic component 30.
• the first metallization level 5 is made of metal, it can well transmit the heat of the electronic component 30 to, for example, a cooling liquid flowing through the channel 35.
• FIG. 5 shows an embodiment of the printed circuit board in which the flexible region 10 is restricted to an edge region that runs around the free space 7.
• FIG. 6 shows an embodiment of a printed circuit board as could emerge from the printed circuit board shown in FIG.
• the flexible region corresponding tongue 6 was bent out of the plane of the cover layer 4 in a further process step.
• the flexibility of the tongue 6 can before bending out through
• FIG. 7 shows an embodiment in which the tongue 6 has been bent out of the plane of the cover layer 4 so far that it is now perpendicular to the cover layer 4.
• elements 40 may be, for example, direction-dependent sensors, displays or actuators. The illustrated arrangement then allows, for example, the detection of movement in all three-space directions.
• FIGS. 8a and 8b show two embodiments of the printed circuit board which additionally each comprise a cap 45.
• FIG. 8 a shows the component from FIG. 7, which additionally encloses all three elements 40 completely by the cap 45.
• FIG. 8b shows a further embodiment which has only two elements 40, which are enclosed by a cap 45 which encloses only a partial region of the printed circuit board.
• FIG. 9 shows an embodiment of the printed circuit board in which the tongue 6 has been bent out of its original position by 180 °.
• tongue 6 now extends beyond the outer edge of the printed circuit board.
• tongue 6 can now be used, for example, as an external connection, for example for electrical connection.
• connections to other circuit boards can be made in a simple way.
• the tongue can 6 can also be used as a heating foil, antenna, capacitive or inductive transmitter / receiver.
• FIGS. 10a to 10c show a further variant of a production method.
• FIG. 10 a shows a circuit carrier 1 and a second metallization level 2 arranged thereon.
• FIG. 10 b shows a printed circuit board which has a recess 8. This printed circuit board could be made, for example, from the circuit board, as shown in Figure 10a, by milling out or etching the recess 8. However, the recess 8 can also be made, for example, with the aid of a laser technology.
• the printed circuit board illustrated in FIG. 1c now additionally has a cover layer 4 with a first metallization level 5. Because of that
• Cover layer 4 is only in contact with the second metallization level 2 and does not protrude into the previously produced recess 8, this forms a free space 7. In this manufacturing method, therefore, a free space 7 is formed without a sacrificial layer being specially applied for this purpose and later having to be removed again.
• the cover layer 4 of the first metallization level 5 can be laminated, for example, to the second metallization level 2. So that the cover layer 4 does not flow into the recess 8, so-called no-flow laminates, for example, can be used for the cover layer 4.
• Such no-flow laminates can be made, for example, on a resin or epoxy basis. You can also have for reinforcing a stabilizing fabric or other reinforcing elements.
• FIG. 10 c shows an embodiment in which a cover layer 4 is provided both on the upper side and on the underside was applied. This symmetrical design ensures, for example, that there is no tension in the circuit board. This tension can arise, for example, that different materials are used for the circuit substrate 1 and the cover layer 4.
• FIGS. 11a to 11d the flexible region 10 of a printed circuit board is shown schematically in plan view for different process stages.
• FIG. Ha shows the flexible region 10 with the cover layer 4 and the first metallization plane 5 applied thereto.
• the first metallization level 5 is in this case formed to strip conductors and contact surfaces 9.
• Figure Hb the flexibility of the areas in which the contact surfaces 9 of the first metallization 5 are located through
• Recesses 50 increased.
• the manufacturing of the recesses 50 can be done for example by means of a laser.
• the flexibility of the cover layer 4 in the areas in which the contact surfaces are, is still limited here, since these sections are still connected via the corners in each case with the environment.
• an electronic component 55 set up on the flexible portion 10 of the circuit board and electrically contact via the contact surfaces 9.
• a solder paste can be used.
• the electronic component 55 is shown only with its outline.
• Figure Hd after placing the electronic component 55 more
• Cutouts 60 made. Due to these further recesses, the flexible areas in which the contact surfaces 9 are located have no corners over the corners Connection more to their environment. The flexibility of these sections has been significantly increased by the additional recesses 60 again. Thus, the electronic component 55 is connected to the circuit board only via very flexible elements in connection. Through the recesses 50 and 60, as well as by the curved guide of the tracks, in addition, the flexibility of the flexible portion 10 is increased with respect to tension in the direction of the circuit board level.
• Preferred contacting methods between the electronic component 55 and the contact surfaces 9 are soldering, conductive adhesives, thermosonic bonding and thermocompression bonding with the aid of metallic bumps (stud bumps).
• the first two methods can easily be performed on the flexible contact surfaces 9.
• the latter two methods are preferably used as long as the flexible region 10 is still supported by the delamination layer 3, since in this case considerable vertical forces act.
• a circuit board may also include a circuit carrier 1 having flexible regions 10 on two opposite sides.
• the printed circuit board additionally comprises a barrier layer, which between the
• This barrier layer may comprise, for example, a lacquer or a metal. Such an additional barrier layer can prevent possible influences of the cover layer 4 during its hardening on the delamination layer 3.
• a delamination layer 3 is formed in the printed circuit board, but this is not removed again.
• a material may be used on which the cover layer 4 does not adhere.
• floated polymers such as PTFE for this purpose.
• the flexible area 10 comprises only the first metallization level 5 and none
• the first metallization level 5 may be stabilized on its upper side by an additional layer.
• a corresponding contact surface which may be formed, for example, in the second metallization 2.
• the corresponding contact surface is arranged so that when the flexible region 10 is pressed in between the first metallization plane 5 or the region which is designed as a contact surface 9 and the corresponding contact surface, an electrically conductive contact can be established. In this way, for example, push buttons can be manufactured.
• the flexible region 10 can also comprise a plurality of first metallization planes 5, which can be separated, for example, by a plurality of cover layers 4 which lie between them. In this case, each first metallization level 5 can be shaped differently. Thus, for example, the four traces shown in Figure 11 could be in four different planes.
• Bonding wire or other flexible connection is possible.
• the reason for this is that in a fixed connection, for example, a direct soldering of the component on the circuit board, excessive mechanical stresses would occur in the component.
• the flexible areas mean that no stresses occur in the applied component.
• the clearance 7 is formed as a cavity
• the cavity is filled with a soft or gelatinous mass, so that the flexible portion 10, which is pressed into the cavity, either stabilized or spring back.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing & Machinery (AREA)
• Structure Of Printed Boards (AREA)

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• 2008
  • 2008-06-13 DE DE102008028300.2A patent/DE102008028300B4/de not_active Expired - Fee Related
• 2009
  • 2009-06-08 US US12/997,867 patent/US9035189B2/en active Active
  • 2009-06-08 WO PCT/EP2009/057051 patent/WO2009150133A1/de not_active Ceased
  • 2009-06-08 JP JP2011512955A patent/JP2011523223A/ja active Pending

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