DESCRIPTION
DuPont™ Pyralux® TK flexible circuit material is a flexible copper clad laminate and bonding film system specifically formulated for high-speed digital and high-frequency flexible circuit applications. With a dielectric constant (Dk) of 2.3 to 2.5, and low loss (Df) of 0.0015 to 0.002 depending on the ratio of Teflon™ to DuPont™ Kapton® polyimide film.
The clad dielectric is a proprietary layered composite of Teflon™ and Kapton® films. The available copper foils are 12, 18 and 36 micron rolled annealed (RA) copper, and 12, 18 and 36 micron low profile electrodeposited (ED) copper foil.
The bonding film is also a layered dielectric, made with Teflon™ and Kapton® films. The bonding film contains a T eflon™ film that is procesd at a lower lamination temperature than the clad. APPLICATIONS
Pyralux® TK laminate and bondply films are designed for high speed flex applications, including microstrip and stripline controlled impedance constructions. Key property advantages are:• Low dielectric constant
• Low loss tangent
• Low moisture absorption
• Tight thickness tolerance
• Better flexibility
• Thin—50, 75, and 100 microns CONSTRUCTIONS
TK Dielectric is a composite made from a Kapton® core and thickness of T eflon™ above and below. There are three thickness of cladply dielectric available.
Pyralux® TK flexible circuit material is available in a variety of thickness. TK clads with RA copper end in R; clads with ED copper end in E. Asymmetric constructions such as TK1810036R are available on request.
™®
ED versions of above constuctions are available.
Add “R” to the end of the code to specify rolled-annealed copper foil (e.g.,
TK185018R). Add “E” to the end of the code to specify electro-deposited copper foil (e.g., TK185018
E).
™®
PACKAGING
Pyralux® TK clads are supplied in a sheet form, with standard dimensions of 24” x 36”, 24” x 18”, and 12” x 18” (610 x
914mm, 610 x 457mm, and 305 x 457mm). Other dimensions are available upon request.
Pyralux® TK bonding films are supplied on 610 mm (24 in) wide by 76 m (250 ft) long rolls, on nominal 76 mm (3 in) cores. Other widths and lengths are also available, as well as sheets.
DUPONT™ PYRALUX® TK FLEXIBLE CIRCUIT MATERIALS
™®
*IPC-TM-650-2.5.5.5 value to be ud in design calculations. **In-plane values are bulk properties measured by ASTM-D-2520HAST Conditions are: 2 atm, 120°C, 90% humidity, 96 hours. MIT Flex Test: 18 µm copper lines, 0.38 mm radius
™®*IPC-TM-650-2.5.5.5 value to be ud in design calculations. **In-plane values are bulk properties measured by ASTM-D-2520
UL V-0
IPC-4204/13 (clad)IPC-4203/5 (bonding film)
RoHS Compliant Pb-Free alloy compatible
SPECIFICATIONS
The above stackups were made to compare the performance of DuPont™ Pyralux® TK clad and bondply to the
追悼词母亲
含有山的成语
AP clad and LF bondply. The data in the next two graphs show data bad on the two stripline designs.
Graph above shows the loss in dB/cm up to
蒲公英幼儿园
20 GHz. The TK constructions clearly shows
much lower loss (dB is a log scale).
Graphs above show the impedance at different line widths for the two
形容男的帅的成语constructions. This shows the real advantage of lower Dk for making
controlled impedance circuits. To achieve standard impedance targets at
achievable line widths the AP/LF constructions would need to have a
thicker dielectric between the two ground planes.
Simply replacing AP with TK in a standard flex can deliver flexibility benefits. Both stackups shown are 50 Ohms Single
Ended and 100 Ohms Differential, but the TK stackup is significantly thinner and has much lower modulus than the
standard flex stackup. LF bondply can be ud for short lengths or longer lengths at frequencies less than 2 GHz.
PROCESSING SUGGESTIONS
Dimensional Stability
DuPont™ Pyralux® TK clads will shrink more than most other Pyralux® clads after etching, baking, and lamination. U caution when designing with unbalanced clads to avoid curl after lamination. TK clads will shrink morein the TD direction than in the MD direction. TD is always listed first in clad dimensions. To reduce shrinkage keep as much copper as possible on the clads during imaging.
Full copper borders with sunburst channels for air escape will reduced the level of shrinkage after etching better than the dot pattern often ud. When laminating TK bondply to TK clads, bleeder channels must be prent to prevent entrapped air during lamination.
Clad Preparation for Bondply Lamination
Adhesion of treated copper foil to TK bondply varies with copper foil type and chemistry. T est adhesion before deciding on copper foil. Adhesion of TK bondply to shiny copper requires a good microetch of 25 – 50 microinches or more to achieve good adhesion. Alternative oxides yield higher adhesion. We successfully tested:• Cobra Bond (OMG Group)
• Circubond (Dow, was Shipley)
• Bondfilm (Atotech)
Adhesion of TK bondply to TK clad dielectric is very good but TK bondply does NOT adhere well to Pyralux® AP dielectric. Do not touch or modify the T eflon™ surface of the TK clads after etching (i.e. no pumice scrubbing or plasma etching). This will remove the activated surface, which will reduce adhesion to TK bondply and standard coverlays.
Bondply Lamination
1. Bake sheets of bondply at 121C for 2 hours prior to layup to
remove all moisture from Kapton® layer prior to laminating.
2. Start with cold press.
3. Pull vacuum for at least 30 minutes before applying pressure or
heat.
4. Start pressure and heat. Aim peak temperature to 280 – 290°C
(535 – 554°F). (Do not exceed 300°C (572°F)).
5. Aim pressure to a maximum of 250 psi (1.7 MPa). Lower
pressures generally work better than higher pressures.
6. Ramp rate is not usually critical
7. Hold at peak temperature for 60 minutes to insure best adhesion.8. Cool down under pressure. Cool down rate is not critical after
temperature falls below 260°C (500°F). Cooling down too
quickly above this temperature can lead to registration
problems. TK Bondply adhesion to dielectric and copper
surfaces is mainly determined by peak lamination temperature and time at peak temperature. Pressure has very little effect.
This is even also true for conformation and flow of the TK
bondply adhesive around circuitry.
The long vacuum draw down time before heat and pressure is critical to preventing entrapped air voids. Increasing the
thickness of the press pads is preferred over increasing
pressure to improve encapsulation of traces. Lower pressure can improve registration in many cas.
The long vacuum draw down time before heat and pressure is critical to preventing entrapped air voids, which are a common defect obrved during the development of the TK bondply lamination process. Increasing the thickness of the press pads is sometimes required to eliminate air voids that are obrved in the thin circuit area.
Registration can be an issue with thicker TK multilayer flex circuits. Lower pressure can improve registration in many cas. Press Pad Recommendations
U press pads that can survive 280 to 290°C bondply lamination.
The following press pad systems have been tested to be compatible with TK bondply lamination:
• Themopad (Pacothane Industries)
• HeatShield (MRS Polymers)
• Themofilm (Pacothane Industries)
• Aluminum and Copper Foil
Due to the high temperature and long duration of the lamination, it is generally recommended not to re-u press pads.
Drilling and Through Hole Activation Recommendations The procedures ud today to drill and activate high speed PTFE boards should be adequate for DuPont™ Pyralux® TK flexible circuit mat
erials. The Teflon™ in Pyralux® TK is chemically similar to the PTFE fluoropolymer ud in rigid high speed laminate. Open flute, thin web design drill bits work the best for TK drilling, the are usually marketed as “flex” tools by most tool manufacturers. U new drill bits and limit hit count to 500. It is critical that the drill bits not get so hot that they start to melt the
T eflon™ layers. TK drill results are usually better with chip loads lower than for typical flex circuits. In many cas, Teflon™ smear may occur during drill bit retract. Therefore, hard backing materials that can clean the drill bits before retract work well (such as phenolic).
For circuit constructions with T eflon™ and other dielectrics, always run the desmear process for non-T eflon™ dielectric first. Then, run the activation process for the T eflon™. Therefore, Pyralux® TK could be desmeared initially in the same process ud for Pyralux® AP and then followed by a T eflon™ preparation. None of the methods below will remove T eflon™ smear; they will only activate the surface for plating
Options for Teflon™ Activation
Sodium Etch: This is a Sodium Napthalene solution available from Poly-Etch or Fluoro-Etch. It works well and has been ud for many years. Most PCB manufacturers who routinely run high speed PTF
E boards will already have sodium etch available. Plasma Etching: The T eflon™ can be prepared for plating with plasma etching. Run one of the gas as the last cycle. They are listed in order of most effective.
• Nitrogen/hydrogen mixtures (from 70/30 to 30/70) – Most effective
如何拆空调• Helium – If Nitrogen/Hydrogen is not available
牛王滩
The general goal is to remove the fluorine from the surface of the T eflon™ to improve wetting. That is why the standard gas for other dielectrics (CF4/02) should never be the last plasma gas ud in a multistage process.
The activation of the T eflon™ surface is usually effective for 24 to 48 hours. Run electroless copper or direct plate within 1 to 2 days after hole wall activation.
Lar Drilling脚痒痒怎么回事
DuPont™ Pyralux® TK works well with Carbon Dioxide lars. We do not recommend lar drilling vias with standard UV lars since the T eflon™ is transparent to the UV energy. Routing with UV lars is possible if edge quality is not critical.Coverlays
Pyralux® LF and FR coverlays are compatible with Pyralux® TK laminate. Using TK bondply as a coverlay is not recommended since the flow of the Teflon™ is very difficult to precily control for pad openings.
Rigid-Flex
We recommend that the outer surface of the flex be TK clad and not TK bondply. The TK Bondply surface does not adhere as well to prepregs.
When laminating flex sublayers with TK clads and bondplies for rigid flex application, leave solid copper on the outerlayers during lamination step. Then image the outerlayers after lamination. This will make registration more manageable and improve adhesion of the prepregs to the surface of the TK clads. TK etched circuits should NOT be plasma etched before low flow prepreg lamination. GENERAL INFORMATION黑色氧化物
Handling
Pyralux® TK laminate and bondply are more nsitive to static build up than traditional flexible circuit materials becau of the low moisture levels. After etching, handle sample carefully to prevent collection of particulate.
Safe Handling
Anyone handling DuPont™ Pyralux® TK flexible circuit materials should wash their hands with soap before eating, smoking, or using restroom facilities. Although DuPont is not aware of anyone developing contact dermatitis when using DuPont™ Pyralux® TK products, some individuals may be more nsitive than others. Gloves, finger cots, and finger pads should be changed daily. DuPont™ Pyralux® TK flexible circuit materials are fully cured when delivered. However, lamination areas should be well ventilated with a fresh air supply to avoid build-up from trace quantities of residual solvent (typical of polyimides) that may volatilize during press lamination. When drilling or routing parts made with DuPont™ Pyralux® TK, provide adequate vacuum around the drill to minimize worker exposure to generated dust. As with all thin, copper-clad laminates, sharp edges prent a potential hazard during handling. All personnel involved in handling Pyralux® TK clads should u suitable gloves to minimize potential cuts.
