JP2024162995A - Flexible Printed Circuit Copper Overlay for Thermal Management - Google Patents

Abstract

To provide a flexible printed circuit (FPC) that reduces a maximum temperature across various layers of a laminate of the FPC, prevents damage to the FPC, and improves a manufacturing yield.SOLUTION: An FPC 355 of a hard disc drive includes a plurality of fingers extending from a main portion. Each of the fingers includes: a first wiring layer 362 including a first conductive trace layout; a second wiring layer 366 including a second conductive trace layout; and a base film interposed between the first wiring layer and the second wiring layer. The first conductive trace layout includes at least one thermal conductive protection island 372 that overlays a corresponding portion of the second trace layout in order to provide the base film with a protective thermal barrier.SELECTED DRAWING: Figure 3B

Description

Embodiments of the present invention may relate generally to hard disk drives and, in particular, to techniques for managing temperature across a flexible printed circuit (FPC) during an interconnect procedure.

A hard disk drive (HDD) is a non-volatile storage device housed in a protective enclosure and stores digitally encoded data on one or more circular disks with magnetic surfaces. When the HDD is in operation, each magnetic recording disk is rapidly rotated by a spindle system. Data is read from and written to the magnetic recording disks using read/write heads (or "transducers") that are positioned over specific locations on the disks by an actuator. The read/write heads use magnetic fields to write data to and read data from the surfaces of the magnetic recording disks. The write head works by generating a magnetic field using electrical currents that flow through its coils. Electrical pulses are sent to the write head in different patterns of positive and negative currents. The electrical current in the write head's coils creates a localized magnetic field across the gap between the head and the magnetic disk, which then magnetizes small areas on the recording medium.

To write data to the medium or read data from the medium, the head needs to receive instructions from the controller. Therefore, the head is connected to the controller in some electrical way so that the head can not only receive instructions to read/write data, but also send information about the read and/or written data back to the controller. Typically, a flexible printed circuit (FPC) stack is used to electrically transmit signals from the read/write head to other electronics in the HDD through the suspension tail. The FPC and suspension tail are typically soldered together to the comb or "E-block" portion of the head stack assembly (HSA) (see, for example, carriage 134 in FIG. 1). To connect them with solder, the suspension electrical pads and the FPC electrical pads are heated. A low soldering temperature may not melt the solder, but a high soldering temperature may damage these components by heat. For example, one or more layers that make up the FPC stack may peel off or develop bubbles in response to the heat generated by the soldering procedure. Therefore, it is desirable not to overheat the FPC during the electrical interconnection procedure, which may otherwise damage the FPC and result in a corresponding reduction in production yield.

Any approach that may be described in this section is an approach that could be pursued, but not necessarily an approach that has been previously conceived or pursued. Thus, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.

Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numbers refer to similar elements.

FIG. 1 is a plan view showing a hard disk drive according to an embodiment.

FIG. 1 illustrates a perspective view of an actuator assembly, according to an embodiment.

FIG. 2 is a perspective view illustrating an electrical interconnection between a suspension tail and a flexible printed circuit (FPC) according to an embodiment.

FIG. 2 is a plan view showing an FPC according to an embodiment.

FIG. 2D is a cross-sectional view of the FPC of FIG. 2C according to an embodiment.

FIG. 13 is a plan view showing FPC fingers according to an embodiment.

FIG. 13 is a plan view showing overlaid FPC fingers according to an embodiment.

FIG. 3C is a cross-sectional view of the FPC of FIG. 3B according to an embodiment.

FIG. 13 is a plan view showing overlaid FPC fingers according to an embodiment.

FIG. 2 is a plan view of a flexible printed circuit (FPC) according to an embodiment.

1 is a flow chart illustrating a method of making a flexible printed circuit (FPC) laminate composition, according to an embodiment.

Generally, an approach is described for providing a substantially uniform temperature across a flexible printed circuit (FPC) during an interconnection procedure. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. It will be apparent, however, that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices may be shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention described herein.
Introduction Terms

References herein to "an embodiment," "one embodiment," and the like are intended to mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the invention. However, instances of such phrases do not necessarily all refer to the same embodiment.

The term "substantially" is understood to describe features that are largely or approximately structured, configured, dimensioned, etc., although manufacturing tolerances and the like may result in situations in which in practice the structure, configuration, dimensions, etc. are not always or necessarily exactly as stated. For example, describing a structure as "substantially vertical" assigns its unequivocal meaning to the term, such that the sidewalls are for all practical purposes vertical, but may not be exactly 90 degrees overall.

Terms such as "optimum,""optimization,""minimum,""minimization,""maximum,""maximization," and the like may not have specific values associated with them, but as such terms are used herein, it is intended that one of ordinary skill in the art will understand such terms to include influencing values, parameters, metrics, and the like, in a beneficial direction consistent with the entirety of this disclosure. For example, describing something as a "minimum" does not require that the value actually be equal to some theoretical minimum (e.g., zero), but should be understood in a practical sense in that the corresponding goal is to move that value toward the theoretical minimum in a beneficial direction.
context

At the distal end of the suspension is a read/write transducer (or "head") for reading and writing data. At the other proximal end of the suspension are conductive pads (or simply "electrical pads") for electrically connecting to corresponding conductive pads on a flexible printed circuit (FPC). The suspension pads and FPC pads are typically electrically interconnected (orthogonally in this example) by solder using solder reflow, hot air, or a laser that may be used to heat the materials in a bonding procedure.

2A is a perspective view of an actuator assembly according to an embodiment. The actuator assembly 200 comprises a carriage 201 (see, for example, carriage 134 in FIG. 1 ) rotatably coupled to a central pivot shaft (not shown here, see, for example, pivot shaft 148 in FIG. 1 ) by a pivot bearing assembly (not shown here, see, for example, pivot bearing assembly 152 in FIG. 1 ) and rotatably driven by a voice coil motor (VCM) in which a voice coil 204 is shown. The actuator assembly 200 further comprises one or more actuator arms 206 (see, for example, arm 132 in FIG. 1 ), each of which houses a read/write head 210 (see, for example, read/write head 110a in FIG. 1 ) and is typically coupled to a suspension assembly 208 (see, for example, lead suspension 110c in FIG. 1 ) including a swaged base plate 208a, a load beam 208b (see, for example, load beam 110d in FIG. 1 ), and a suspension tail 208c. Each suspension assembly 208 is electrically connected to a flexible printed circuit (FPC) 212 coupled to the carriage 201 by a suspension tail 208c.

FIG. 2B is a perspective view showing an electrical interconnection between a suspension tail and a flexible printed circuit (FPC) according to an embodiment. FIG. 2B shows the suspension tail tip 208e of the suspension tail 208c (FIG. 2A) mechanically and electrically coupled to the corresponding FPC finger 212a of the FPC 212 by solder 211 (or some other electrical connection means). In particular, the electrical pad 208d on the suspension tail tip 208e is electrically connected to the electrical pad 212d of the FPC 212. As mentioned above, in soldering and other similar connection techniques, the suspension electrical pads and the FPC electrical pads are heated, and if the soldering temperature is too low, the solder may not melt, and if the soldering temperature is too high, the FPC may be damaged by the heat. In the worst case, air bubbles may appear in the FPC. That is, one or more layers that make up the FPC stack may peel off in response to the heat generated by the soldering/interconnection procedure. For example, delamination may occur between one or more wiring layers and adjacent insulating film layers due to failure of the corresponding adhesive layers, etc. Therefore, it is desirable to heat the FPC evenly to avoid generating excessive heat that may damage the FPC.

Figure 2C is a top view of a flexible printed circuit according to an embodiment, where an FPC 212 includes a number of FPC fingers 212a, each of which includes a number of electrical pads 212d on its top and bottom sides. Each FPC finger 212a typically services both a UP head (a read/write head facing upward to service the bottom surface of a corresponding disk) and a DN head (a read/write head facing downward to service the top surface of the same disk), and electrically connects the corresponding UP suspension and DN suspension, respectively, to a preamplifier 220 (or more) attached to the FPC 212. A cross section of an FPC finger 212a is labeled A-A.

FIG. 2D is a cross-sectional view showing the FPC of FIG. 2C, according to an embodiment. Cross-section A-A shows a layer of an FPC, such as FPC 212, including a base film 254 (e.g., a polyimide insulating layer) interposed between a first wiring layer 252 (e.g., including copper traces) on top and a second wiring layer 256 (e.g., including copper traces) on the bottom, whereby each of the first wiring layer 252 and the second wiring layer 256 can be used for both UP and DN heads and can vary from implementation to implementation. The first wiring layer 252 is covered by a first cover film 250 (e.g., a polyimide insulating layer), and the second wiring layer 256 is covered by a second cover film 258 (e.g., a polyimide insulating layer). These wiring layers 252, 256 can be electrically connected by one or more vias. Additionally, there is typically an adhesive layer between the wiring layers 252, 256 and each of the adjacent film layers 250, 254, 258. Finally, all of the aforementioned layers are bonded to and supported by a bottom stiffener layer 260 (e.g., comprising aluminum, or some other rigid and durable material). The exact layout of FPC 212 may vary from implementation to implementation, so the layout of Figure 2D is presented as an example, however, the techniques described herein are generally applicable to alternative FPC layouts.
Overlaid copper for thermal management of flexible printed circuit fingers

FIG. 3A is a plan view of an FPC finger, according to an embodiment. Here, the white areas/patterns of the FPC 300 represent the top first wiring layer 352 (similar to the layout of the first wiring (e.g., copper) layer 252 in FIG. 2D) and the cross-hatched areas/patterns represent the bottom second wiring (e.g., copper) layer 356 (similar to the layout of the second wiring layer 256 in FIG. 2D). To keep the temperature of the FPC 300 relatively low, it is generally effective to have a relatively small copper area because copper absorbs heat. FIG. 3A shows a relatively large second wiring layer 356 compared to the relatively small first wiring layer 352. When these wiring layers 352, 356 are heated, the larger second wiring layer 356 will be hotter. Thus, the relatively small second wiring layer 356 is better at absorbing heat. However, it may not be feasible to minimize the area of the second wiring layer 356 beyond a certain point and still achieve its intended purpose.

3B is a front view showing the overlaid FPC fingers, and FIG. 3C is a cross-sectional view of the FPC of FIG. 3B, both according to an embodiment. A cross-section of a portion of FPC 355 having vias 374 is labeled section B-B in FIG. 3B, and referring to section B-B in FIG. 3C, an FPC laminate composition is shown including bottom stiffener layer 370, second cover film 368 (e.g., polyimide insulating layer), second wiring layer 366, base film 364 (e.g., polyimide insulating layer), first wiring layer 362 connected to second wiring layer 366 by vias 374, and cover film 360 (e.g., polyimide insulating layer). Here, thermally conductive protection islands 372 (e.g., copper) have been added to the first wiring layer 362 to overlay portions of the second wiring layer 366, providing a thermal barrier to the second wiring layer 366 as well as other layers surrounding the second wiring layer 366 (e.g., base film 364, second cover film 368), thereby protecting the second wiring layer 366 as well as other layers surrounding the second wiring layer 366 from excessive heat. Again, the white areas/patterns of the FPC 355 represent the upper or first wiring layer 362 (similar to the layout of the first wiring layer 252 in FIG. 2D ) and the cross-hatched areas/patterns represent the lower or second wiring layer 366 (similar to the layout of the second wiring layer 256 in FIG. 2D ). 3B shows a plurality of thermally conductive guard islands 372 that make up the first wiring layer 362 and are positioned to protectively overlay or cover portions of the second wiring layer 366. Preferably, each guard island 372 of the first wiring layer 362 is thermally connected to the second wiring layer 366 by a corresponding via 374. This connection prevents excessive heat buildup within the guard islands 372 that could otherwise damage other layers (e.g., the first cover film 360, the base film 364, the second cover film 368).

It should be noted that, by their function and/or by their respective corresponding signals, some pairs of upper and lower electrical pads of the FPC 355 are electrically connected to each other. Thus, the upper pad 380a is connected to the lower pad 380b, the upper pad 382a is connected to the lower pad 382b, the upper pad 384a is connected to the lower pad 384b, and the upper pad 386a is connected to the lower pad 386b. It can therefore be considered to connect the pads 384a and 384b by the adjacent guard island 372. However, this indicates that the temperature of the pads 384a, 384b is too low for a proper solder connection due to the large area of the adjacent guard island and the heat it absorbs. The embodiment of FIG. 4 can address this issue.

4 is a plan view of an overlaid FPC finger, according to an embodiment. Again, thermally conductive protective islands 372 (e.g., similar to FPC 355 in FIG. 3B) are added to the first wiring layer 462 to overlay portions of the second wiring layer 466, providing a thermal barrier to the second wiring layer 466, as well as other layers, protecting them from excessive heat. Similarly, the white areas/patterns of FPC 400 represent the first wiring layer 462 (similar to the layout of first wiring layer 362 in FIG. 3B, FIG. 3C), and the cross-hatched areas/patterns represent the second wiring layer 466 (similar to the layout of second wiring layer 366 in FIG. 3B, FIG. 3C). 4 shows a narrow wiring trace 401a electrically connecting the upper pad 484a with the guard island 372, and a similar narrow wiring trace 401b electrically connecting the lower pad 484b with the same guard island 372. These wiring traces 401a, 401b are utilized to increase heat resistance compared to a more direct connection of the pads 484a and 484b with the adjacent guard island 372, thereby allowing sufficient heat to be generated for proper solder connection to each pad 484a, 484b. According to an embodiment, "narrow" is characterized herein as each wiring trace 401a, 401b having a width that is one-fifth (1/5) or less than the width of the corresponding upper and lower pads 484a, 484b. Thus, in a non-limiting example, each of the wiring traces 401a, 401b may have a width of approximately 30 μm or less, with each of the upper pads 484a and lower pads 484b having a width of approximately 150 μm.

5 is a plan view of a flexible printed circuit (FPC) according to an embodiment. The FPC 512 includes a plurality of FPC fingers 512a, each of which includes a plurality of electrical pads 512d on its upper and lower sides. Here, at least a portion 513 of the cover film (similar to the layout of the cover film 250 in FIG. 2D or the cover film 360 in FIG. 3C) is made of a colored material, since a colored cover film (e.g., white) typically reflects more light and more heat than a transparent cover film. According to an embodiment, the colored portion 513 of the cover film is white.

In summary, each of the foregoing embodiments features an approach for managing temperature across a flexible printed circuit, such as during an electrical pad interconnection procedure (e.g., soldering), using the various techniques described, either alone or in combination. Thus, the maximum temperature across the various layers of the FPC stack can be reduced, preventing damage to the FPC and improving manufacturing yields.
Method for manufacturing a flexible printed circuit

Figure 6 is a flow chart illustrating a method for producing a flexible printed circuit (FPC) laminate composition according to an embodiment.

At block 602, a lower wiring layer including a lower conductive trace layout is formed. For example, a second wiring layer 366 (FIGS. 3B, 3C), 466 (FIG. 4) is formed with the conductive trace layout, such as on a base stiffener 370 (FIG. 3C) and a second cover film 368 (FIG. 3C).

At block 604, a base film is formed on the lower wiring layer. For example, base film 364 (FIG. 3C) is formed on second wiring layer 366, 466.

In block 606, an upper wiring layer including an upper conductive trace layout is formed on a base film, including forming at least one thermally conductive guard island overlaying a corresponding portion of the lower trace layout to provide a thermal barrier to the base film. For example, a first wiring layer 362 (FIGS. 3B, 3C), 462 (FIG. 4) including an upper conductive trace layout is formed on a base film 364, including forming at least one thermally conductive guard island 372 (FIGS. 3B, 4) overlaying a corresponding portion of the lower trace layout of a second wiring layer 366, 466 to provide a thermal barrier to the base film 364. According to an embodiment, the first wiring layer 362, 462 is electrically connected to the second wiring layer 366, 466 by vias 374 (FIG. 3C).
Physical Description of Exemplary Operational Contexts

Embodiments may be used in the context of a digital data storage device (DSD), such as a hard disk drive (HDD). Accordingly, to help explain how a conventional HDD typically operates, a plan view illustrating a conventional HDD 100 is shown in FIG. 1, in accordance with an embodiment.

FIG. 1 shows a functional arrangement of components of a HDD 100, including a slider 110b including a magnetic read/write head 110a. Collectively, the slider 110b and the head 110a may be referred to as a head slider. The HDD 100 includes at least one head gimbal assembly (HGA) 110, including a head slider, a lead suspension 110c typically attached to the head slider via a flexure, and a load beam 110d attached to the lead suspension 110c. The HDD 100 also includes at least one recording medium 120 rotatably mounted on a spindle 124, and a drive motor (not shown) attached to the spindle 124 to rotate the medium 120. The read/write head 110a, which may also be referred to as a transducer, includes a write element for writing information stored on the medium 120 of the HDD 100, and a read element for reading the information. The medium 120 or multiple disk media may be secured to the spindle 124 by a disk clamp 128.

The HDD 100 further comprises an arm 132 attached to the HGA 110, a carriage 134, and a voice coil motor (VCM) including an armature 136 including a voice coil 140 attached to the carriage 134, and a stator 144 including a voice coil magnet (not shown). The VCM armature 136 is attached to the carriage 134 and configured to move the arm 132 and the HGA 110 to access a portion of the media 120, all of which are collectively mounted on a pivot shaft 148 with an intervening pivot bearing assembly 152. In a HDD with multiple disks, the carriage 134 may be referred to as an "E-block" or comb because the carriage is arranged with a ganged array of arms that gives it the appearance of a comb.

An assembly including a head gimbal assembly (e.g., HGA 110) including a flexure to which a head slider is coupled, an actuator arm (e.g., arm 132) and/or a load beam to which the flexure is coupled, and an actuator (e.g., VCM) to which the actuator arm is coupled may be collectively referred to as a head stack assembly (HSA). However, an HSA may include more or less components than those described. For example, an HSA may refer to an assembly that further includes electrical interconnection components. In general, an HSA is an assembly configured to move a head slider to access a portion of a medium 120 for read and write operations.

1, electrical signals including write signals to and read signals from head 110a (e.g., current to the voice coil 140 of the VCM) are transmitted by a flexible cable assembly (FCA) 156 (or "flex cable", or "flexible printed circuit" (FPC)). The interconnect between flex cable 156 and head 110a may include an arm electronics (AE) module 160, which may have an on-board preamplifier for the read signal, as well as other read channel and write channel electronics. AE module 160 may be mounted to carriage 134 as shown. Flex cable 156 may be coupled to an electrical connector block 164 that, in some configurations, provides electrical communication via an electrical feedthrough provided by HDD housing 168. The HDD housing 168 (or "enclosure base" or "base plate" or simply "base"), together with the HDD cover, provides a semi-sealed (or, in some configurations, hermetically sealed) protective enclosure for the information storage components of the HDD 100.

Other electronic components, including a disk controller and servo electronics including a digital signal processor (DSP), provide electrical signals to the drive motor, the voice coil 140 of the VCM, and the head 110a of the HGA 110. The electrical signals provided to the drive motor enable it to rotate, which imparts torque to the spindle 124. This torque is then transferred to the medium 120 secured to the spindle 124. As a result, the medium 120 rotates in a direction 172. The rotating medium 120 creates a cushion of air that acts as an air bearing on which the air bearing surface (ABS) of the slider 110b rests, allowing the slider 110b to float above the surface of the medium 120 without contacting the thin magnetic recording layer on which the information is recorded. Similarly, in HDDs utilizing a lighter-than-air gas, such as helium as a non-limiting example, the rotating medium 120 creates a cushion of gas that acts as a gas or fluid bearing on which the slider 110b rests.

Electrical signals provided to the voice coil 140 of the VCM allow the head 110a of the HGA 110 to access the track 176 on which information is recorded. Thus, the armature 136 of the VCM swings through an arc 180, which allows the head 110a of the HGA 110 to access various tracks on the medium 120. Information is stored on the medium 120 in a number of radially nested tracks arranged in sectors on the medium 120, such as sector 184. Correspondingly, each track is made up of a number of sectorized track portions (or "track sectors"), such as sectorized track portion 188. Each sectorized track portion 188 may include a header that includes the recorded information, as well as error correction code information and a servo burst signal pattern, such as an ABCD servo burst signal pattern, which is information that identifies the track 176. In accessing track 176, the read element of head 110a of HGA 110 reads a servo burst signal pattern that provides a position error signal (PES) to the servo electronics that control the electrical signal provided to the voice coil 140 of the VCM, thereby enabling head 110a to follow track 176. Having found track 176 and identified a particular sectored track portion 188, head 110a reads information from or writes information to track 176 in response to instructions received by a disk controller from an external agent, such as a microprocessor in a computer system.

The electronic architecture of a HDD includes numerous electronic components, such as a hard disk controller ("HDC"), an interface controller, an arm electronics module, a data channel, motor drivers, a servo processor, and buffer memory, each performing a respective function for the operation of the HDD. Two or more of such components may be combined on a single integrated circuit board referred to as a "system on a chip" ("SOC"). Some, but not all, of such electronic components are typically located on a printed circuit board that is coupled to the bottom side of the HDD, such as the HDD housing 168.

References herein to hard disk drives, such as HDD 100 shown and described with reference to FIG. 1, may encompass information storage devices sometimes referred to as "hybrid drives." A hybrid drive generally refers to a storage device that combines the functionality of both a conventional HDD (see, e.g., HDD 100) and a solid-state storage device (SSD) using electrically erasable and programmable non-volatile memory, such as flash or other solid-state (e.g., integrated circuit) memory. Because the operation, management, and control of different types of storage media are typically different, the solid-state portion of the hybrid drive may include its own corresponding controller functionality, which may be integrated into a single controller along with the HDD functionality. A hybrid drive may be designed and configured to operate and utilize the solid-state portion in several ways, such as, by way of non-limiting examples, to store frequently accessed data, to store I/O intensive data, and the like, by using the solid-state memory as a cache memory. Additionally, a hybrid drive may be designed and configured essentially as two storage devices in a single enclosure, i.e., a conventional HDD and an SSD, with one or more interfaces for host connection.
Augmentations and Alternatives

In the foregoing description, the embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, various modifications and changes may be made without departing from the broader spirit and scope of the embodiments. Thus, the sole and exclusive indication of what the invention is and what the applicant intends the invention to be is the set of claims issued from this application in the particular form in which the claims are issued, including any subsequent amendments. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of the terms as used in the claims. Hence, any limitations, elements, properties, features, advantages or attributes not expressly set forth in the claims should in no way limit the scope of such claims. Hereby, the specification and drawings are to be regarded in an illustrative and not restrictive sense.

Also, in this description, certain process steps may be described in a particular order, and alphabetic and alphanumeric labels may be used to identify the particular steps. Unless otherwise specified in the description, embodiments are not necessarily limited to any particular order of performing such steps. In particular, the labels are merely used for convenient identification of the steps, and are not intended to specify or require a particular order of performing such steps.

Also, in this description, certain process steps may be described in a particular order, and alphabetic and alphanumeric labels may be used to identify particular steps. Unless otherwise specified in the description, embodiments are not necessarily limited to any particular order of performing such steps. In particular, the labels are merely used for convenient identification of steps, and are not intended to specify or require a particular order of performing such steps.
This specification discloses the following items.
(Item 1)
a plurality of fingers extending from the main portion, each finger comprising:
a first wiring layer including a first conductive trace layout;
a second wiring layer including a second conductive trace layout;
a base film interposed between the first wiring layer and the second wiring layer;
The first conductive trace layout includes at least one thermally conductive protective island overlaying a corresponding portion of the second conductive trace layout to provide a protective thermal barrier to the base film.
(Item 2)
2. The FPC of claim 1, wherein the at least one thermally conductive guard island is electrically connected to the second wiring layer by a via.
(Item 3)
Each finger is
an upper narrow conductive trace connecting an upper electrical pad of said first wiring layer to an adjacent selected protection island;
2. The FPC of claim 1, further comprising: a lower narrow conductive trace connecting a lower electrical pad of the first wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pad to the lower electrical pad.
(Item 4)
further comprising a non-transparent cover film on the first wiring layer;
2. The FPC according to item 1.
(Item 5)
Further comprising a white cover film on the first wiring layer;
2. The FPC according to item 1.
(Item 6)
a transparent cover film on the first wiring layer;
a white second cover film over at least a portion of the transparent cover film of each finger;
2. The FPC according to item 1.
(Item 7)
2. A hard disk drive comprising the FPC according to item 1.
(Item 8)
1. A method for making a flexible printed circuit (FPC) laminate composition, comprising:
forming a lower wiring layer including a lower conductive trace layout;
forming a base film on the lower wiring layer;
forming an upper wiring layer on the base film including an upper conductive trace layout, the upper wiring layer including forming at least one thermally conductive protective island overlying a corresponding portion of the lower conductive trace layout to provide a protective thermal barrier to the base film.
(Item 9)
forming a via connecting the at least one thermally conductive guard island of the upper wiring layer to the lower wiring layer.
The method according to item 8.
(Item 10)
forming upper narrow conductive traces connecting the upper electrical pads of said upper wiring layer to adjacent selected protection islands;
forming a lower narrow conductive trace connecting a lower electrical pad of the upper wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pad to the lower electrical pad.
The method according to item 8.
(Item 11)
forming a non-transparent cover film over at least a portion of the upper wiring layer.
The method according to item 8.
(Item 12)
forming a white cover film on at least a portion of the upper wiring layer;
The method according to item 8.
(Item 13)
forming a transparent cover film on the upper wiring layer;
forming a white second cover film over at least a portion of the transparent cover film.
The method according to item 8.
(Item 14)
Item 9. An FPC produced according to the method described in item 8.
(Item 15)
a plurality of recording media rotatably mounted on a spindle;
a plurality of head sliders, each housing a corresponding read/write transducer configured to read from and write to at least one of the plurality of recording media;
means for moving the plurality of head sliders to access portions of the at least one recording medium;
a means for transmitting signals from the plurality of head sliders to HDD electronics, comprising:
The means for transmitting comprises:
a plurality of fingers extending from the main portion, each finger comprising:
a first wiring layer including a first conductive trace layout;
a second wiring layer including a second conductive trace layout;
a base film interposed between the first wiring layer and the second wiring layer;
the first conductive trace layout includes at least one thermally conductive guard island overlaying a corresponding portion of the second conductive trace layout to provide a protective thermal barrier to the base film; and a means for transmitting.
(Item 16)
Item 16. The HDD of item 15, wherein the at least one thermally conductive guard island is electrically connected to the second wiring layer by a via.
(Item 17)
Each finger is
an upper conductive trace connecting an upper electrical pad of the first wiring layer to an adjacent particular guard island;
16. The HDD of claim 15, further comprising: a lower conductive trace connecting a lower electrical pad of the first wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pad to the lower electrical pad.
(Item 18)
The means for transmitting comprises:
Item 16. The HDD of item 15, further comprising a non-transparent cover film on the first wiring layer.
.
(Item 19)
The means for transmitting comprises:
Item 16. The HDD of item 15, further comprising a white cover film on the first wiring layer.
(Item 20)
The means for transmitting comprises:
a transparent cover film on the first wiring layer;
and a second cover film of white color over at least a portion of the transparent cover film of each finger.

Claims (20)

a plurality of fingers extending from the main portion, each finger comprising:
a first wiring layer including a first conductive trace layout;
a second wiring layer including a second conductive trace layout;
a base film interposed between the first wiring layer and the second wiring layer;
The first conductive trace layout includes at least one thermally conductive protective island overlaying a corresponding portion of the second trace layout to provide a protective thermal barrier to the base film. The FPC of claim 1, wherein the at least one protective island is electrically connected to the second wiring layer by a via. Each finger is
an upper narrow conductive trace connecting an upper electrical pad of said first wiring layer to an adjacent selected protection island;
2. The FPC of claim 1, further comprising: a lower narrow conductive trace connecting opposing electrical pads of the first wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pads to the lower electrical pads. further comprising a non-transparent cover film on the first wiring layer;
The FPC according to claim 1 . Further comprising a white cover film on the first wiring layer;
The FPC according to claim 1 . a transparent cover film on the first wiring layer;
a white second cover film over at least a portion of the transparent cover film of each finger;
The FPC according to claim 1 . A hard disk drive comprising the FPC according to claim 1. 1. A method for making a flexible printed circuit (FPC) laminate composition, comprising:
forming a lower wiring layer including a lower conductive trace layout;
forming a base film on the lower wiring layer;
forming an upper wiring layer on the base film including an upper conductive trace layout, the upper wiring layer including forming at least one thermally conductive protective island overlying a corresponding portion of the lower trace layout to provide a protective thermal barrier to the base film. forming a via connecting the at least one protection island of the upper wiring layer to the lower wiring layer.
The method according to claim 8. forming upper narrow conductive traces connecting the upper electrical pads of said upper wiring layer to adjacent selected protection islands;
forming lower narrow conductive traces connecting opposing electrical pads of the upper wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pads to the lower electrical pads.
The method according to claim 8. forming a non-transparent cover film over at least a portion of the upper wiring layer.
The method according to claim 8. forming a white cover film on at least a portion of the upper wiring layer;
The method according to claim 8. forming a transparent cover film on the upper wiring layer;
forming a white second cover film over at least a portion of the transparent cover film.
The method according to claim 8. An FPC manufactured according to the method of claim 8. a plurality of recording media rotatably mounted on a spindle;
a plurality of head sliders, each housing a corresponding read/write transducer configured to read from and write to at least one of the plurality of recording media;
means for moving the plurality of head sliders to access portions of the at least one recording medium;
a means for transmitting signals from the plurality of head sliders to HDD electronics, the means for transmitting comprising:
a plurality of fingers extending from the main portion, each finger comprising:
a first wiring layer including a first conductive trace layout;
a second wiring layer including a second conductive trace layout;
a base film interposed between the first wiring layer and the second wiring layer;
the first conductive trace layout includes at least one thermally conductive guard island overlaying a corresponding portion of the second trace layout to provide a protective thermal barrier to the base film; and a means for transmitting. The HDD of claim 15, wherein the at least one protective island is electrically connected to the second wiring layer by a via. Each finger is
an upper conductive trace connecting an upper electrical pad of the first wiring layer to an adjacent particular guard island;
16. The HDD of claim 15, further comprising: lower conductive traces connecting opposing electrical pads of the first wiring layer to the adjacent particular guard island, thereby electrically connecting the upper electrical pads to the lower electrical pads. The means for transmitting comprises:
16. The HDD of claim 15, further comprising a non-transparent cover film on the first wiring layer. The means for transmitting comprises:
The HDD of claim 15 further comprising a white cover film on the first wiring layer. The means for transmitting comprises:
a transparent cover film on the first wiring layer;
16. The HDD of claim 15, further comprising: a second cover film that is white over at least a portion of the transparent cover film of each finger.