Hard disk Flex PCB application

Hard disk Flex PCB application
Heavy Copper Flex PCB
Photo Credit: Robert Tarzwell
Heavy Copper Flex Circuit Boards

San Francisco Circuits can provide heavy copper flex circuit boards that can also be coupled with flexible thin copper layers designed to handle heavier power currents. Your heavy copper boards can be built with flex portions for lower voltage additions and applications.

Double-Sided & Multi-Layer Flex PCBs

By definition a Flex PCB is a patterned arrangement of printed circuitry and components that utilizes flexible based material with or without flexible coverlay. These flexible electronic assemblies may be fabricated using the same components used for rigid printed circuit boards, but allowing the board to conform to a desired shape (flex) during its application.

With the escalating demands of the computer market, continuing the trend of handling data reliably at increasingly faster data rates is crucial for the next generation of products. Just as the overall performance of the computer can be limited by the slowest peripheral, all of the components throughout the hard disk drive (HDD) must, similarly, be designed to support the very high speeds needed to maintain the performance of the system.

One link in the chain of components within the HDD that needs to be carefully designed is the interconnect between the pre-amplifier and the read/write magnetic head assembly. This is a key component in providing the necessary speed and control that will allow HDDs to read and write huge amounts of data at multi-Gb/s rates. However, undesired effects, such as crosstalk, overshoots, and undershoots often hinder the performance of the interconnect, significantly delaying the design process, or worse, the time-to-market or performance of the product.

To meet these challenges, engineers at 3M Asia Pacific are integrating electronic design automation (EDA) technology into their design cycle for an HDD flexible interconnect to ensure state-of-the-art performance while meeting internal development time and cost goals. The results they obtain through simulation have been validated against Time Domain Reflectometry (TDR).

Design objectives

Key Specifications/Special Features:
Single-sided (adhesive-less) copper clad: 1/2, or 1, -mil PI 1/2oz RA/ED copper
Coverlay: 1-mil 25um adhesive
Stiffener: 0.2mm PI
Double sided tape: 3M 467
Surface finishing: electroless nickel immersion gold plating
100% electrical tested
Sample time and lead-time:
Single sided FPC: 2 days
Double sided/bare back FPC: 4 days
Rigid-flex/split flexes/others multiple layers: 6 days
Mass production lead-time: <2 weeks (included tooling fabrication)
Volume flexibility: high-mix and low-volume
About company:
Flex-plus (Xiamen) company limited was formed in 2004 and strategically located in Guannan industrial zone, Jimen district, Xiamen city, Fujian province, China

What is Flexible PCB?

A Flex Circuit or Flex PCB is a patterned arrangement of printed circuitry and components that utilizes flexible based material with or without flexible coverlay.
These flexible electronic assemblies may be fabricated using the same components used for rigid printed circuit boards, but allowing the board to conform to a desired shape (flex) during its application.

Rigid flex circuits have been used in the military and aerospace industries for more than 20 years. In most rigid flex circuit boards, the circuitry consists of multiple flexible circuit inner layers selectively attached together using an epoxy pre-preg bonding film, similar to a multilayer flexible circuit. However, a multilayer rigid flex circuit incorporates a board externally, internally or both as needed to accomplish the design.

Rigid flex circuits combine the best of both rigid boards and flexible circuits integrated together into one circuit. The two-in-one circuit is interconnected through plated thru holes. Rigid flex circuits provide higher component density and better quality control. Designs are rigid where extra support is needed and flexible around corners and areas requiring extra space.

While the design options are endless when combining rigid boards with flexible circuits, we have provided you with rigid flex combinations that are most commonly utilized.

Flex circuits are fully surface mountable to accommodate: surface mount, chip-on-flex, as well as flip-chip technology. Our strategic partnerships give you the benefits you'd expect from our flex circuits manufacturing team, and you can be rest assured your flex circuits or Rigid-Flex circuit products will be of premium quality.

Flex circuits are commonly used in many applications spanning many markets including today's: wearable products, consumer electronics, medical devices, military, and aerospace. Common applications include: laptop computers, ink jet printers, hard disk drives, optical storage drives, cellular phones, video tape recorders, flat panel displays, etc.

Precision Technologies flex material selections

Polyimide Films:- 0.5 mil (.0005″), 1 mil (.001″), 2 mils (.002″), 3 mils (.003″), 5 mils (.005″)

Thermobond Adhesives:- Acrylic/Modified Acrylic, Phenolic Butyral, Modified Epoxy

Copper Foils (rolled-annealed):- 1/4 oz , 1/3 oz, 1/2 oz. (.0007″), 1 oz. (.0014″), 2 oz. (.0028″)

Stiffeners:- FR-4, polyimide, metal, or customer supplied

FR-4 in Multi-layer Flex Circuits:- Laminated to flex circuit to create rigid flex boards. Typically with vias.

Surface Finish:- Solder (hot air leveling or electrolytic plating), Electroless Au and Ni, Silver, Tin plating

We manufacture and supply flexi-rigid PCBs and flexible circuit boards. Flexible circuits are constructed by sequential build up of flexible component layers, such as base polyimide, copper, cover-lay, and stiffeners bonded by an adhesive layer (epoxy or acrylic).
Our capability includes single sided, double sided (with or without PTH), multi-layer and flexi-rigid PCBs.
The materials selected must be appropriate for either static (e.g. once only bend into a camera) or dynamic applications (e.g. hard disk drive).
Stiffeners are normally applied in the region of the flexible circuit where components are mounted.
They are more expensive to manufacture than rigid PCBs due to their complexity and the material required. Flexible circuit base materials are more dimensionally unstable than FR4 rigid laminate, and have to be processed on smaller step & repeated blanks.
Mechanical tooling is selected according to the volume and accuracy required. Tooling may be either CNC soft tooling (low cost but high unit costs), steel rule (volumes up to a few thousand pieces, medium cost, low dimensional stability), or hard steel punch & die sets (durable, accurate, & high cost).
Who uses the service?
Frequent customers are those clients who seek a reliable supplier of flexible circuits or PCBs. Clients may be development engineers, researchers, or contract manufacturers. Our usual customers value local support, confidentiality, and good communications. We manufacture any quantity from prototype sample boards upwards.

Flexible PCB / FPCB Applications
FPCBs are used widely in everyday
technology and electronics in addition
to high-end, complex completed components.

Two of the most prominent examples
of flexible circuit usage is in modern
portable electronics, devices,
hard disk drives and desktop printers.

Flexible circuits are also used extensively in other applications and industries including:
Communications
Consumer Electronics
Automotive
Medical Industrial
Aerospace
Military Transportation
Stack up of Flexible PCB

Flex-plus provides a niche market in fabrication of high dense single side, double sided, multi layers, rigid flexes, split flexes and sculpture flex in the usage of all electronic products
Our experienced team of engineers can provide up front technical assistance to help develop the full package that is from product conceptualization to delivery
With our one stop solution in mind, our competent staff will cater to your every needs to it be designed, flex fabrication or component assembly
Flex-plus will be there in your time of need and the speed of our solution will simply thrill our every extremely demanding customers
In flex-plus, quality is of the paramount as we have obtained the ISO 9001:2008 and ISO 14001 and all appropriate UL certifications
We will assure you that our quality application are built in, processed and delivered with unique values expected of us
We drive aggressive goals towards our prototype and first manufacturing lead time which will be extremely customers oriented cycle time
In this global time constrain environment, those who move the fastest, leads the race
Flex-plus is such and with passion of excellence strive to be the best

The motivation for using EDA tools for this application is to reduce the amount of time required to design a product and to get it to market and to achieve a more robust design. Robustness is accomplished by allowing the design-layout-analyze-debug cycle to be executed more frequently, much more quickly, and at a significantly lower cost than could ever be realized by building and measuring physical prototypes.

Design challenges

3M Microflex Circuits are thin, lightweight signal traces built on substrates with precisely engineered circuit features. They are used in IC packaging, HDD, medical devices, printers, and other high-density applications. Flexible circuit technology enables smaller, lighter, and faster products and can lower total applied cost.

The circuit of particular interest in this study is a Flex on Suspension (FOS) structure used for an HDD Head Gimbal Assembly (HGA). Design guidelines are three-fold: mechanical compliance, process dependency, and electrical performance.

Mechanical Compliance - Stiffness of the HGA must be minimized in the gimbal area to ensure compliance of the head to the media flight height. This calls for a reduction in circuit conductor height and, therefore, affects the overall impedance of the circuit.

Process Dependency - The present process capability from 3M is 25 microns trace width and spacing.

Electrical Performance - Controlled impedance is required throughout the entire flex circuit, from the driver chip output to the giant magneto-resistive read/write head.

PCB Unlimited understands that customers are often looking for a one stop shop to handle their flex circuit design, fabrication, as well as assembly needs to reduce product handling and lead time associated with out-sourcing each of these tasks. Whether your idea is a sketch or diagram, we'll help you design a cost-effective interconnect solution. We are also set up to handle component assembly including connectors and various surface mount components. Presented are common capabilities. Come speak to us concerning tighter tolerances or special process requirements.

FLEX AND RIGID FLEX PCB APPLICATIONS
RFPCB's are products using a combination of flexible and rigid board technologies in one application. Depending upon the design of the application, rigid flex PCB's typically consist of multiple layers of flexible circuit substrates attached to one or more rigid boards externally and/or internally, depending upon the design of the application. The flexible substrates are designed to be in a constant state of flex and are usually formed into the flexed curve during manufacturing or installation.
Rigid-flex circuitry provides a simple means to integrate multiple PCB assemblies and other elements such as display, input or storage devices without wires, cables or connectors, replacing them with thin, light composites that integrate wiring in ultra-thin, flexible ribbons between sections. In rigid-flex packaging, a flexible circuit substrate provides a backbone of wiring with rigid multiplayer circuit sections built-up as modules where needed.

Flex PCBs are used widely in everyday technology and electronics in addition to high-end, complex completed components. Two of the most prominent examples of flexible circuit usage is in modern portable electronics, devices, hard disk drives and desktop printers.
Flexible circuits are also used extensively in other applications and industries including: Communications , Industrial, consume electronics, aerospace, military, medical, and transportation.

Whether you're looking for a double sided flex circuit or complex multi layer flexible PCBs from your flex PCB manufacturer, we can provide you with the guidance, expertise and capabilities to bring your concept to reality. Multi-layer flex boards are being used more often in electronic applications for higher speed performance but at a loss of flexibility. Single-sided or double-sided multi layer flex PCBs can be designed in unique and complex layouts, with a much greater possibility of combinations compared to FR4 board design. Just as multi-layer FR4 boards, the multi layer FPCBs can be designed using blind and buried vias as well as plated through holes (PTH).

Our strong network of manufacturers can push the limits on PCB fabrication technology, with very fine 1 mil traces, RF PCB or HDI PCB technology and more!

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Hard disk Flex PCB application

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Hard disk Flex PCB application