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MEGTRON 6/6G is advanced material designed for high-speed network equipment, mainframes, IC testers and high frequency measuring instruments. The main attributes of MEGTRON 6/6G are: low dielectric constant and dielectric dissipation factors, low transmission loss and high heat resistance; Td = 410°C (770°F). MEGTRON 6/6G meets IPC specification 4101 /102 /91.
Megtron 6 laminates come in 18 thicknesses, complemented by a wide range of prepreg thicknesses and glass styles, including various tightly woven, so-called flat-glass styles to avoid impedance variation caused by fiber-weave effect. Resin evenly coats the surface of those tight weaves. Three different percentages of resin content can be selected for several of the Megtron 6 prepreg glass styles.
The most significant contrast is that Megtron 6 laminates the same as conventional FR-4 materials; no incompatible pressures, temperature, movement, or cure time are involved. Hybrid boards can be built in a single lamination with inner layers of relatively inexpensive FR-4 materials and an outer layer or layers of Megtron 6, using foil construction or cap construction. Moreover, the wider selection of Megtron 6 core and prepreg thicknesses and resin content eases stackup development and impedance control.
PCB materials with stable Df values on the order of 0.003 up to at least 10GHz are necessary to meet channel loss budgets in high-speed digital applications as network line cards for 40-Gbit/s and faster data rates. Various materials, some of them widely used in RF circuit boards, have Df values low enough to satisfy the loss budgets of high-speed signal paths on 40-Gbit/s Ethernet line cards, for example, within safe margin. These materials cost more than regular FR-4 laminates, so hybrid stackups are common that dedicate high-speed nets to low-loss layers and less-critical circuits to layers of FR-4 for economy.
At Hemeixinpcb, we have been in a long term association with Rogers Corporation, who is a world’s leading manufacturer of high performance dielectrics, laminates and prepregs. With specialty high frequency circuit materials sourced from Rogers Corporation, we build PCBs with high-frequency and high-speed performance. Our range of Rogers PCBs are designed to offer greater thermal performance in severe application environments.
Comparing to the conventional PCB plate epoxy resin, this kind of PCB is different. Most PCB plates are made of a material known as FR-4(Flame Retardant level 4), which is a glass fiber/epoxy composite with copper foil laminated on one or both sides. FR-4 material has a base standard of PCB substrates, which gives a widely effective balance between cost, manufacturability, electrical properties, durability, and performance. On the other hand, Rogers will provide us FR-4laminates (FR-4 core with copper laminate) since they are better known for cores with better high-frequency properties, such as PTFE (Teflon). Although Rogers materials are more expensive than fiberglass, they are less lossy at high frequencies. This makes this kind of PCB material is good for RF circuit boards. When the working frequency of the circuit is above 500MHz, the number of materials that can be chosen by the design engineer becomes significantly smaller. Usually, a radio engineer will use the term “Roger's PCB” when they want to mention “Circuit board with Teflon cores”. But actually, Rogers also makes many types of PCB cores other than a circuit board with Teflon cores, while many companies also produce Teflon cores.
To sum up, there are several differences between the FR-4 material and Rogers material:
1. FR-4 material is less expensive than Rogers material.
2. Comparing to FR-4 material, Rogers material is better for high-frequency applications.
3. For dielectric constant (Dk), FR-4 has Dk value of about 4.5, which is lower than Rogers material with around 6.15 to 11.
4. In temperature management, Rogers material has a less variation comparing to FR-4 material
5. FR-4 material has a high Df (dissipation factor) than Rogers material, suffering more signal loss. 6. In impedance stability, Rogers material has a wider range of Dk values than FR-4 material.
Different kinds of Roger’s materials. By using Advanced Circuit Material, Rogers PCB wants to accommodate hardware engineers to build such circuits with the high-frequency, high-speed performance for wired & wireless communications. Rogers’ Products/Brands include RT/duriod® High-Frequency Laminates; RO4000® High-Frequency Circuit Materials; RO3000® High Frequency Laminates; and TMM® Thermoset Microwave Materials. Each product has its characteristics and benefits. Below are the details of each Rogers’ product:
Rogers RT/duroid® high-frequency circuit materials are filled PTFE (irregular glass or ceramic) composite coversfor use in high reliability, aviation and defense applications. The RT/duroid types have a long industry nearness of providing high-reliability materials with predominant performance. This kind of material has several benefits:
1 Low electrical loss,
2. Low moisture absorption,
3. Stable dielectric constant (Dk) over a wide frequency range, and
4. Low outgassing for space applications.
RO3000 laminates are ceramic filled PTFE composites intended for use in the commercial microwave and RF applications. R03000 series laminates are circuit materials with very consistent mechanical properties regardless of the dielectric constant selected. Due to this characteristic, when designing multi-layer boards with varying dielectric constants, there will be very little issues if any at all The dielectric constant VS temperature of RO3000 series materials is very stable. RO3000 laminates also are available in a wide range of dielectric constants (3.0 to 10.2). The most common applications are:
1. Surface mount RF components,
2. GPS antennas, and
3. Power amplifiers.
RO4000 laminates and pre-pregs possess favorable properties that are highly useful in microwave circuits and instances where controlled impedance is needed. This series of laminates are very price optimized and are also fabricated using standard FR4 processes which makes it suitable for multi-layer PCBs. Additionally, it can be processed lead-free. The series of RO4000 laminates offer a range of dielectric constants (2.55-6.15) and are available with UL 94 V-0 flame retardant versions. The most popular applications of this are:
1. RFID chips,
2. Power amplifiers,
3. Automotive radars, and
The RO4350B hydrocarbon ceramic laminate from Rogers has been developed for high-frequency, low cost applications. The laminate can be fabricated into printed circuit boards using standard FR-4 circuit board processing techniques. Unlike PTFE based high performance materials, this series of laminates do not require specialized via preparation processes such as sodium etch. This material is a rigid, thermoset laminate that is capable of being processed by automated handling systems and scrubbing equipment used for copper surface preparation.
The RO4350B laminate has a Dk of 4, Df of 0.0031 to 0.0037 and can be used up to frequencies of up to 40 GHz. It can be used to develop RF & microwave circuits, matching networks and controlled impedance transmission lines.
Rogers TMM® thermoset microwave laminates fuse dielectric constant uniformity, low thermal coefficient of dielectric constant (Dk), and a copper matched coefficient of thermal expansion. Because of their electrical and mechanical stability, TMM high-frequency laminates are perfect for high-reliability strip-line and micro-strip applications. This kind of material has several benefits:
1. Wide range of dielectric constants (Dks),
2.Excellent mechanical properties, cold flow, and resists creep,
3. Exceptionally low thermal coefficient of Dk,
4. Coefficient of thermal expansion fit to copper taking into account high reliability of plated through-holes,
5. Available copper clad in larger formats, allowing the use of standard PCB subtractive processes,
6. No wreck to materials during fabrication and assembly processes, Resistant to process chemicals,
7. Thermoset resin for reliable wire bonding,
8. No specialized production techniques required,
9. TMM 10 and 10i laminates can replace alumina substrates, and
10. RoHS compliant, environmentally friendly.Below is a table that shows the characteristics of various types of PCB materials.
High-Performance RF PCB Materials. Suppose you want to build a 2.5-GHz Bluetooth module and the RF traces are about an inch long total, would you really consider the 0.3-dB signal loss, especially when you know that the antenna matching circuit possibly produce more loss than this? Maybe not. The next step up in improving on FR-4 is to use a high-performance material like Rogers PCBs (e.g. RO4350B) and others. The RO4350B PCB loss is less than half the loss of FR-4 at 6 GHz. While this may not be excessively significant and not worth the additional expense if your circuit works at under 6 GHz, at 10 GHz the losses are even less and FR-4 really begins to show its shortcoming.
These materials can work well up to the 20-GHz-plus range with really high-performance, plus having a very stable and repeatable Er. Besides, the Er of these materials is also usually much lower, being on the order of 3.6, and the Er is essentially flat with frequency since it is a higher grade Glass Epoxy” material. If your circuit design uses distributed elements or matching networks in the multi-GHz range then there is really a no better choice than these types of materials for lot-to-lot consistency. Moreover, instead of based on glass epoxy, these materials usually have a ceramic filler which really improves the thermal conductivity. Huge numbers of these materials can likewise endure lead-free assembly temperatures well indeed. But of course, there is no free lunch! All of this performance comes with a cost; your board cost, to be specific. Another option to designing a multilayer PCB with all high-performance material is to develop a hybrid Glass Epoxy/high-performance material type board. This method is when you use a material like the high-performance Rogers RO4350B on the outside layers where the RF components and Microstrip traces use a lower-cost Glass Epoxy inside. In which, the power and control traces reside. This Hybrid-type construction works out quite well and can save a substantial amount on your board costs. Please make sure to check the details with your board manufacturer although you are already confident that the materials you want to use are compatible with each other.
Many PCBs have been built using Rogers 4350B material for very high-speed digital circuits. It is a proven choice from a functional perspective, and a highly predictable material from a manufacturing perspective, with well-established fabrication protocols.
Rogers offers three prepreg choices for bonding the 4350B laminates: a 4-mil prepreg that is available in two glass styles and one that is 3.6-mils thick with one glass style. Rogers discourages etchback of the material, advises against using a single layer of prepreg in high-layer-count, single-lamination stackups, and recommends cap construction. Manufacturers have to adjust the lamination cycle for fabricating boards when the Rogers material is involved because of the restriction on using a single layer of prepreg. The Rogers prepregs for the 4350B cores require higher pressure for proper lamination than do the Panasonic prepregs,which process no differently than conventional FR-4 materials. The Rogers core material is essentially perfectly flat and repeatable, aiding impedance control; the Panasonic material slightly less so. The Rogers material is at least twice as expensive as Megtron 6. Eight laminate thicknesses are available.
FR408HR laminate and prepreg products are manufactured with Isola’s patented high performance multifunctional resin system, reinforced with electrical grade (E-glass) glass fabric. This system delivers a 30% improvement in Z-axis expansion and offers 25% more electrical bandwidth (lower loss) than competitive products in this space. These properties coupled with superior moisture resistance at reflow, result in a product that bridges the gap from both a thermal and electrical perspective.
The FR408HR system is also laser fluorescing and UV blocking for maximum compatibility with Automated Optical Inspection (AOI) systems, optical positioning systems and photo-imagable solder mask imaging.
High Frequency circuits require substrate materials that have tight control of dielectric constant as well as low loss. Materials that meet these requirements traditionally have been priced much higher than conventional epoxy/glass boards. The emergence of the commercial high frequency market has brought about a strong need to balance performance, manufacturability and cost. Rogers RO4003C™ High Frequency Material bridges the gap by providing tight control on dielectric constant, and low loss, while processing the same as standard epoxy/glass at a fraction of the cost of conventional microwave laminates. RO4003C materials are proprietary woven glass reinforced hydrocarbon/ceramics with the electrical performance of PTFE/woven glass and the manufacturability of epoxy/glass.
An evaluation of insertion loss for a 50Ω microstrip transmission line was conducted on several materials. The materials selected range from standard FR4 (difunctional epoxy), to the more sophisticated PTFE based laminates (GX and RO3003™). The goal of the evaluation was to quantify the circuit losses on the various types of materials. This would enable one to better understand the frequency limitations of each material type.
RO4003C material provides loss comparable to RO3003 and GX material. A large increase in loss is evident when going to the next material, BT glass. The lossiest material, difunctional epoxy, is 4.5 times lossier than the RO4003C laminate. Overall when selecting a material during the design stages, issues like;
need to be considered in order to reduce cycle time of the design.
There are many materials being evaluated for commercial high frequency applications, but once performance and cost are evaluated, the choices narrow down to a few, RO3003, GX and RO4003 among them. These remaining choices provide good Er control as well as low loss, critical for frequencies at C-band (4 to 8 GHz) and above. RO4003C materials not only provide the needed electrical characteristics, but can also be manufactured with standard epoxy/glass processes, bringing down fabrication costs. In general, RO4003C materials combine the best of electrical properties with ease of fabrication at a competitive cost for commercial applications
RT/duroid® 5870 and 5880 glass microfiber reinforced PTFE composites are designed for exacting stripline and microstrip circuit applications. Glass reinforcing microfibers are randomly oriented to maximize benefits of fiber reinforcement in the directions most valuable to circuit producers and in the final circuit applications.
The dielectric constant of RT/duroid laminates is uniform from panel to panel and is constant over a wide frequency range. Its low dissipation factor extends the usefulness of RT/duroid 5870 and 5880 laminates to Ku-band and above.
RT/duroid 5870 and 5880 laminates are easily cut, sheared and machined to shape. They are resistant to all solvents and reagents, hot or cold, normally used in etching printed circuits or in plating edges and holes.
Available with a range of copper cladding options.
RT/duroid® 5880LZ materials have the lowest Dk for a copper clad laminate available in the market today. Because of its low dielectric constant of 1.96 at 10 GHz, RT/duroid 5880LZ supports broadband applications at the microwave through millimeter-wave frequencies where dispersion and circuit losses must be minimized. It is a lightweight, PTFE-based composite optimized with a unique filler that provides very low density (1.37 gm/cm3) and a low coefficient of thermal expansion (CTE) in the Z-axis. This makes 5880LZ well suited for fabricating high-frequency circuits with plated-through holes (PTH) and allows higher vehicle payloads. In addition, the dielectric constant is uniform from panel-topanel and constant over a wide frequency range, with a low Z-axis TCDk of +22 ppm/°C. Its low dissipation factor extends the usefulness of RT/duroid 5880LZ to Ku-band and above.
Astra MT77 laminate materials exhibit exceptional electrical properties which are very stable over a broad frequency and temperature range. Astra MT77 is suitable for many of today’s commercial RF/microwave printed circuit designs. It features a dielectric constant (Dk) that is stable between -40°C and +140°C at up to W-band frequencies. In addition, Astra MT77 offers an ultra-low dissipation factor (Df) of 0.0017, making it a cost-effective alternative to PTFE and other commercial microwave laminate materials.Key applications include long antennas and radar applications for automobiles, such as adaptive cruise control, pre-crash, blind spot detection, lane departure warning and stop and go systems.
The development of Isola Astra MT77 laminate and prepreg materials has garnered several eye-balls, particularly among PCB manufacturers. These materials will find applications in several mm-Wave systems. Astra MT77 is a low loss FR-4 process compatible laminate and prepreg. Isola Astra MT77 offers exceptional physical properties including broad operational frequency and higher temperature range. These laminates are highly preferred for commercial RF/microwave printed circuit designs and mm-Wave applications.
Isola introduced Astra MT77 during the event of the IEEE Microwave Theory and Techniques Society’s 2019 IMS Microwave Week. Some of the major applications of Astra MT77 include long-range antennas and radar applications for automobiles. The increasing popularity of these materials for applications involving adaptive cruise control, pre-crash, and blind spot detection is expected to drive demand for these laminates over the coming years. These laminates also found applications in lane departure warning and stop and go systems.
Astra MT77 displays exceptional electrical characteristics such as better dielectric constant (Dk) within a temperature range of -40°C and +140°C at W-band frequencies, and higher stability. In addition, Isola Astra MT77 provides an ultra-low dissipation factor (Df) of 0.0017. Several applications involving the mm-Wave frequency band prefer an ultra-low dissipation factor. Astra MT77 materials are an ideal substitute for PTFE and other types of microwave laminate materials, due to their cost-effective nature.
Some of the exclusive features include wide-spread industry recognition and RoHS Compliance. Astra MT-77, an ultra-low loss FR-4 process compatible laminate is also lead-free PCB assembly compatible. Some processing advantages include shorter lamination cycle, lower drill wear, good flow and fill, and higher dimensional stability. This type of laminate does not require plasma de-smear, which helps to reduce manufacturing cost as well. However, processing of these laminates requires several lamination cycles. Moreover, Isola Astra MT77 is an HDI technology compatible, which will likely to drive its demand in the near future.
With the rise of 5G, the new wireless world, and an increasing number of mm-Wave applications, demand for advanced PCB materials will likely to escalate over the coming years. Furthermore, 5G technology will likely drive demand for an ultra-low loss FR-4 process compatible laminate and add more value to the PCB industry.
Very high speed and very low loss (RF/microwave): Materials for RF/microwave applications have the flattest Dk versus frequency response and the least dielectric loss. They are suitable for up to 60GHz applications. An example of this material is Isola Tachyon 100G.
Tachyon 100G laminate materials are designed for very highspeed digital applications up to and beyond speeds of 100 Gb/s. Tachyon 100G materials exhibit exceptional electrical properties that are very stable over a broad frequency and temperature range. Tachyon 100G is suitable for scaling current products to their next generation through design of new backplanes and daughter cards, enabling almost 10x improvements from 10 Gb/s data rates. Tachyon 100G targets line cards that require the highest thermal performance. It has identical electricals as Tachyon, but offers a 30% improvement in Z-axis CTEs on high-layer count PCBs. This makes it a perfect choice for higher layer line cards that have multiple 2 oz. planes and BGAs with pitches at 0.8 mm or less.
Tachyon 100G products use spread glass and reduced profile copper to mitigate skew and improve rise times, reduce jitter, increase eye width and height. Use of ultra smooth cooper is enabled by very high adhesive bond between the resin and the metal. Tachyon 100G has a nominal dielectric constant (Dk) of 3.02 that is stable between -55°C and +125°C up to 40 GHz. In addition, Tachyon 100G offers a very low nominal dissipation factor (Df) of 0.0021.
Tachyon 100G laminate materials are available in optimized laminate and prepreg forms in typical thicknesses and standard panel sizes to provide a complete material solution for high-speed digital multilayer backplanes and daughter cards.
The Isola representatives pointed to two laminates, the second of which was just introduced in late June 2014, Tachyon and Tachyon-100G, respectively, which they recommend for building router backplanes, line cards, and PCBs for other very high-speed digital applications. The two laminates have identical electrical characteristics, including a Df of 0.002 and a Dk of 3.02 that is invariant up to 40 GHz.
Tachyon-100G was introduced to target very high-speed line cards (100-Gb/s Ethernet) because of its thermal stability, in particular a very low coefficient of expansion in the Z-axis, suiting it, especially to such high-layer-count constructions. Both the materials use spread glass along with very low-profile copper foil (2 μm Rz surface roughness) to help minimize weave-induced differential skew, cut signal rise times and reduce jitter and intersymbol interference. The materials come in a wide range of prepreg and core thicknesses and are processed in the same manner as typical FR-4 laminates. They can be used as either a core or prepreg in hybrid FR-4 builds.
Any materials with the sort of dielectric and thermal performance as described are welcome additions to a PCB manufacturer’s catalog of laminates, especially since they do not involve the complications inherent in processing PTFE-based materials. I’ll provide comparisons with other laminates in the near future.
Let’s discuss key manufacturing considerations when dealing with hybrid PCB stack-ups. First, make sure all the materials in your hybrid stack-up are compatible with your lamination cycle. Some materials need higher temperatures and pressures than others in the lamination process. Before you submit your design, check your material data sheets to confirm compatible materials are being used.
I-Speed® is a proprietary high performance 180°C glass transition temperature (Tg) FR-4 system for multilayer Printed Wiring Board (PWB) applications where maximum thermal performance and reliability are required. I-Speed laminate and prepreg products are manufactured with Isola’s patentable high performance
multifunctional resin system, reinforced with electrical grade (E-glass) glass fabric. This system delivers a 15% improvement in Z-axis expansion and offers 25% more electrical bandwidth (lower loss) than competitive products in this space. These properties coupled with superior moisture resistance at reflow, result in a product that bridges the gap from both a thermal and electrical perspective.
I-Speed IS is a product extension of I-Speed, manufactured with Isola’s patentable high performance multifunctional resin system, reinforced with electrical grade (low Dk) glass fabric. The low Dk glass significantly reduces the Dk of the material to 3.30, allowing increased trace widths and also reduces skew caused by Dk differences between the glass and resin.
The I-Speed system is laser fluorescing and UV blocking for maximum compatibility with Automated Optical Inspection (AOI) systems, optical positioning systems and photoimagable solder mask imaging.
I-Tera MT40 is suitable for many of today’s high speed digital and RF/microwave printed circuit designs. I-Tera MT40 features a dielectric constant (Dk) that is stable between -40°C and +140°C up to W-band frequencies. In addition, I-Tera MT40 offers a very low dissipation factor (Df) of 0.0028 - 0.0035 making it a cost effective alternative to PTFE and other commercial microwave and high-speed digital laminate materials.I-Tera MT40 laminate materials are currently being offered in both laminate and prepreg form in typical thicknesses and standard panel sizes. This provides a complete materials solution package for high-speed digital multilayer, hybrid, RF/microwave, multilayer and double-sided printed circuit designs. I-Tera MT40 does not require any special through hole treatments commonly needed when processing PTFE-based laminate materials.
Hemeixin are proud to announce full UL recognition and approval for the manufacture of complex HDI and sequential lamination PCB’s, using Isola I-Tera MT40 laminates and prepregs. Low Dk and very low loss characteristics, coupled with excellent thermal robustness, work in parallel to help support the stringent demands of today’s high speed digital and RF/microwave designs. In addition, this new approval also covers Isola Tachyon 100G, designed to support future advancements in data transfer rates through the use of spread glass and low profile copper foil, resulting in faster rise times, reduced skew and jitter and increased eye width.
Nelco N4000-13 EP is an enhanced epoxy resin system engineered for today’s lead-free requirements where multiple solder reflow at temperatures approaching 260ºC are required. N4000-13 EP provides enhanced thermal reliability without compromising the electrical and signal loss properties that have made the Nelco N4000-13 product family the industry standard for demanding high speed / low loss designs. N4000-13 EP SI is excellent for applications that require optimum signal integrity and precise impedance control, while maintaining high CAF resistance and thermal reliability.
The design of interconnect that support data rate exceeding 50 Gbps is necessary to support Terabit backplane systems. In order to predict and optimize the performance of high-speed links operating at 50 Gbps and beyond, it is essential to accurately model and characterize the interconnect systems. The models of interconnects have to be broadband and include high frequency effects that were not critical at that data rates in the range of 10 to 20 Gbps . For higher data rates, very careful modeling of signal propagation in PCB and package traces requires proper identification of the conductor and dielectric frequency-dependent properties over extremely wide frequency band. In addition, 3D modeling and characterization of transition structures are essential to understand and optimize the wave propagation and minimize mismatch across various transition structures such as via and BGA at the interface between package and PCB.
Low-loss laminates such Megtron 6 from Panasonic, FR408HR from Isola Group, and Nelco 4000-13 EPSI from Park Electrochemical Corp. are expected to be key enablers to design boards to run at higher data rates. These laminates offer much more stable dielectric characteristics and have considerably less loss at high frequencies. To investigate the effect of low-loss laminates and see the impact of surface roughness, dielectric properties, glass weave effects, several boards with Megtron 6 with Hyper Very Low Profile (HVLP) finish and Reverse-Treated Foil (RTF) finish, Nelco 4000-13 EPSI with RTF copper foil and standard glass weave, Isola FR408HR with RTF copper foil and standard glass weave. It shows typical electric properties of these low-pass laminates that are studied in this paper and of typical FR-4 board for comparison
The manufactured boards were cross-sectioned to accurately verify all the dimensions of the transmission lines. It shows the cross-section of the board with Isola’s FR408HR, Nelco N4000-13 EPSI, Megtron 6 with RTF and HVLP finishes. The dimensions for the conductor thickness, width, the trace spacing, and the top and bottom layer heights are all marked in microns (µm)
Scattering parameter measurements are taken with a 4-port 67-GHz vector network analyzer (VNA) using high-frequency probes with 200 um-pitch GSSG configuration and high-frequency snap-on connectors. The two set of differential nets with 6-in. and 12-in.long traces for FR408HR, Nelco N4000-13 EPSI, Megtron 6 with RTF, and HVLP finish are measured. The measured differential and common mode insertion loss for the 12 in.traces of the four boards are show. The simulated insertion losses of similar structures using FR4 boards are also plotted for comparisons. The plots show attenuations that agree with the electrical properties of these laminates given in Table I. The measured differential insertion loss of the Megtron 6 with HVLP finish shows about 2 dB improvement over that of the Megtron 6 with RTF finish at 25 GHz. The Megtron 6 with HVLP finish also shows about 4 dB and 6 dB improvements over Nelco N4000-13 EPSI and FR408HR, respectively. The 12-in. trace in Megtron 6 with HVLP laminate shows about 20 dB less loss when compared to similar trace in FR-4 board
The differential group delays of the 12-in. traces are calculated from the measured four-port S-parameters. The delays per inch of the four boards are plotted as functions of frequency. The simulated group delay for FR-4 board is also included in the plots. The Nelco N4000-13 EPSI shows the smallest delay as expected from the dielectric constant value of this laminate given. The typical FR-4 shows the longest delay as predicted from its higher dielectric constant.
Time-domain simulations are also performed using the measured S-parameters to calculate the single-bit response for an excitation of a pulse with amplitude of 1 V and width of 20 ps (corresponding to a data rate of 50 Gbps) and rise and fall time of 8 ps. It shows that the single-bit responses of the Megtron 6 board experienced the least attenuations as predicted by glancing at the differential insertion loss shown. On the other hand, the single-bit responses for FR-4 suffered the larger attenuation and edge degradation closely followed by FR408HR when compared to the Megtron 6 boards. Although the single-bit response of the Nelco N4000-13 EPSI suffered similar attenuation and dispersion as FR408HR, it experienced the least delay due to its low dielectric constant.
TU-872 SLK is based on a high performance modified epoxy FR-4 resin. This material is reinforced with regular woven E-glass and designed with low dielectric constant and low dissipation factor for high speed low loss and high frequency multilayer circuit board application. TU-872 SLK material is suitable for environmental protection lead free process and also compatible with FR-4 processes. TU-872 SLK laminates also exhibit excellent moisture resistance, improved CTE, superior chemical resistance, thermal stability, CAF resistance, and toughness enhanced by an allyl network forming compound.
RF-35 is an organic-ceramic laminate in the ORCER family of Taconic products. It is based on woven glass reinforcement. RF-35 is a result of Taconic’s expertise in both ceramic fill technology and in coated PTFE fiberglass.
PTFE is a thermoplastic material which is very stable electrically and chemically when compared with common thermosetting resins such as epoxy, polyphenyleneoxide, polyimide and cyanate ester. Part of what gives PTFE its superior performance over frequency and temperature also makes the pure resin relatively soft. It is for this reason that all Taconic laminates are reinforced with glass fabric. The glass fabric reinforcement of the substrate greatly increases stability in the X and Y axis over non-woven or unreinforced PTFE products. While the glass fabric provides excellent dimensional
RF-35 is the best choice for low cost, high volume commercial microwave and radio frequency applications. And excellent peel strength for 1/2 ounce and 1 ounce copper (even in comparison to standard epoxy materials), a critical aspect whenever rework is required. And ultra low moisture absorption rate and low dissipation factor minimize phase shift with frequency.
The RF-35 from Taconic is a Laminate with Dk (Dielectric Constant) 3.5 +/- 0.1, Df (Dissipation Factor) 0.0018.
TLX offers reliability in a wide range of RF applications. This material is versatile due to its 2.45 - 2.65 DK range and available thicknesses and copper cladding. It is suitable for low layer count microwave designs.TLX PTFE fiberglass laminates are ideal for use in radar systems, mobile communications, microwave test equipment,
microwave transmission devices and RF components.TLX is a workhorse in the RF microwave substrate world where the fiberglass offers mechanical reinforcement
wherever a substrate experiences severe environments such as:
The wide range of dielectric constants available enable the manufacture of couplers, splitters, combiners, amplifiers, antennas and other components.
ThunderClad 2 ( TU-883 ) is a very low loss category material based on a high performance resin. This material is reinforced with regular woven E-glass and designed with very low dielectric constant and dissipation factor resin system for high speed low loss, radio frequency and wireless applications. ThunderClad 2 material is suitable for environmental protection lead free process and also compatible with FR-4 processes. ThunderClad 2 laminates also exhibit excellent moisture resistance, improved CTE, superior chemical resistance, thermal stability and CAF resistance.
ThunderClad 3+ ( TU-933+ ) is an advanced material designed for high speed computing, telecommunications, radio frequency super low loss filed applications. ThunderClad 3+’s electrical performance is competitive with PTFE-based, hydrocarbon-based very low loss materials, but capable for high layer count circuit board design with excellent thermal reliability.
ThunderClad 3+ laminates also exhibit excellent moisture resistance, improved CTE, superior chemical resistance, thermal stability, CAF resistance, and also compatible with modified FR-4 processes.
RO4835 laminates are a low loss material that offer low cost circuit fabrication, compatible with standard epoxy/glass (FR-4) processes. These laminates are available with Rogers proprietary LoPro® Reverse treated copper foil, ideal for applications requiring low insertion loss.
The RO4835 laminates from Rogers Corporation are high frequency circuit materials that operate up to 40 GHz. They provide 10x more resistance to oxidation than standard RF thermoset materials. The dielectric constant of RO4835 is 3.48 with a dissipation factor of 0.0037 (measured at 10 GHz).
RO4835 laminates, are available with Rogers proprietary LoPro reverse treat copper foil. These materials are ideal for applications requiring low insertion loss characteristics. LoPro foil provides reduced electrical variability due to its smoother copper surface, maintaining consistent performance for reliable broadband signal delivery from Digital through RF and microwave frequencies.
RO4835T laminates, offered in a 2.5 mil, 3 mil and 4 mil core thickness, are 3.3 Dk, low loss, spread glass reinforced, ceramic filled thermoset materials designed for inner-layer use in multilayer board designs, and complement RO4835 laminates when thinner cores are needed. RO4450T Bonding Materials are 3.2-3.3 Dk, low loss, spread glass reinforced, ceramic filled bonding materials that were designed to complement RO4835T and the existing RO4000 laminate family, and come in 3 mil, 4 mil or 5 mil thicknesses. CU4000 and CU4000 LoPro Foils are sheeted foil options for designers looking for foil lamination builds, and provide good outer layer adhesion when used with RO4000 products.
RO4835T laminates and RO4450T bonding materials exhibits excellent Dk control for repeatable electrical performance, a low z axis expansion for plated through hole reliability, and are compatible with standard epoxy/glass (FR-4) processes. These materials are an excellent choice for multilayer designs requiring sequential laminations, as fully cured RO4000 products are capable of withstanding multiple lamination cycles. RO4835T laminates and RO4450T bonding materials have the UL 94 V-0 flame retardant rating, and are compatible with lead-free processes.
Print and etch inner layers using standard image/etch processes (see Inner Layer Preparation). Treat any copper surfaces with appropriate oxide or alternative processes. The PTFE surface of the RF type laminates should not require further treatment if the surface is undisturbed after etching. Scrubbing is not recommended as it will distort the material and remove the mechanical tooth structure imparted by the laminated copper foil. It is this tooth structure which allows mechanical adhesion of the bond ply or prepreg. As mentioned earlier, RF type laminates can be laminated in a pure package or in a mixed package that typically uses an epoxy type laminate or prepreg. The choice of package depends on the electrical performance requirements of the package. Most mixed dielectric packages are designed with the digital or low frequency portion on the epoxy laminate and the high frequency on the RF type laminate. When bonded together, this type of laminate reduces cost, space, connectors, and considerably shortens the distance the signal must travel.
A pure multilayer package of RF type materials can be bonded using Taconic's HT1.5 bonding ﬁlm. This is a thermoplastic ﬁlm with very low electrical loss and has been used in the industry for many years for bonding other types of PTFE based laminates. The HT1.5 bond ﬁlm has a dielectric constant of 2.35 which is signiﬁcantly
different than the dielectric constant of the RF type materials. However, the designer should be able to design with this in mind. Taconic is currently developing a bonding prepreg which will closely match the DK of the RF type materials. HT 1.5 is a thermoplastic and will remelt at approximately 400o F (204oC), therefore care must be taken when multiple or sequential lamination is required or when subjecting the board to thermal excursions such as Hot Air Solder Leveling.
Another bonding ﬁlm used in the industry is FEP, a ﬂuoropolymer-based ﬁlm. The melt point of FEP is approximately 500oF (260oC) and offers greater protection from delamination when the board is subjected to post-lamination thermal cycles such as Hot Air Solder Leveling.
A mixed dielectric package consisting of RF type laminates and other laminates such as epoxy is not common, but can be accomplished quite easily. Bonding RF type laminates to an epoxy laminate is accomplished using standard epoxy prepreg. Since the high frequency RF signal does not see the epoxy due to the ground plane on the RF laminate, the higher loss of the epoxy prepreg does not come into play. Standard epoxy prepreg lamination cycles can be used per the
manufacturer's recommendations. It is important that the RF type laminate is not scrubbed in case there are non-copper areas on the ground plane. The dendrite imprint left after etching the copper foil is critical to good bond strength and must not be disturbed prior to lamination.