Definice high-frequency PCB board

High frequency board refers to the special electromagnetic frequency circuit board, used in high frequency (greater than 300 MHZ frequency or wavelength is less than 1 meter) and microwave (greater than 3 GHZ frequency or wavelength is less than 0.1 meters) in the field of PCB, is on the microwave base copper clad using common rigid circuit board manufacturing method of a part of the process or the use of special processing methods and the production of circuit boards. Obecně lze vysokofrekvenční desky definovat jako obvodové desky s frekvencemi nad 1 GHz.

With the rapid development of science and technology, more and more equipment design is in the microwave band (> 1GHZ) and even with the millimeter wave field (30GHZ) above the application, which also means that the frequency is higher and higher, the substrate of the circuit board requirements are also higher and higher. For example, substrate materials need to have excellent electrical properties, good chemical stability, with the increase of power signal frequency in the substrate loss requirements are very small, so the importance of high frequency plate is highlighted.

Classification of PCB high frequency plate

1, at the end of the ceramic filled thermosetting material

Způsob zpracování:

And epoxy resin/glass woven cloth (FR4) similar processing process, but the plate is more brittle, easy to break, drilling and gong plate drill nozzle and gong knife life is reduced by 20%.

2. Materiál PTFE (polytetrafluorethylen)

Způsob zpracování:

1. Otvor pro materiál: ochranná fólie musí být zachována, aby se zabránilo poškrábání a vroubkování

2. Vrták:

2.1 use a new drill (standard 130), one piece stacked is the best, the presser foot pressure is 40psi

2.2 Hliníkový plech jako krycí deska, poté použijte 1 mm silnou aminovou desku, utáhněte PTFE desku

2.3 Po vrtání vyfoukejte prach z otvoru vzduchovou pistolí

2.4 With the most stable drilling rig, drilling parameters (basically, the smaller the hole, the faster the drilling rate, the smaller Chip load, the smaller the return rate)

3. Zpracování děr

Plazmové ošetření nebo ošetření aktivací sodíkem a naftalenem je prospěšné pro metalizaci pórů

4. PTH umyvadlo měď

4.1.

4.2 If necessary, go through the second PTH, just from the forecast? The cylinder began to enter the plate

5. The resistance welding

5.1 Pre-treatment: use acid washing plate instead of mechanical grinding plate

5.2 After pre-treatment, bake plate (90℃, 30min), brush green oil and cure

5.3 Three baking plates: one is 80℃, 100℃ and 150℃ for 30min each (if oil is found on the substrate surface, it can be reworked: wash off the green oil and reactivate it)

6. Gong board

Lay the white paper on the PTFE board circuit surface, and clamp it with fr-4 base plate or phenolic base plate with a thickness of 1.0mm and copper removal: As shown in the figure:

Jaké jsou vysokofrekvenční desky PCB? Vysokofrekvenční klasifikace desek plošných spojů

Vysokofrekvenční a vysokorychlostní archový materiál

Při výběru substrátu pro PCB pro vysokofrekvenční obvody je třeba věnovat zvláštní pozornost variačním charakteristikám materiálu DK při různých frekvencích. For the requirements of signal high-speed transmission or characteristic impedance control, DF and its performance under the conditions of frequency, temperature and humidity are mainly investigated.

Under the condition of frequency variation, the DK and DF values of general substrate materials change greatly. Zejména ve frekvenčním rozsahu od L MHz do L GHz se jejich hodnoty DK a DF zjevněji mění. For example, the GENERAL epoxy – glass fiber substrate material (general FR-4) has a DK value of 4.7 at lMHz and a DK value of 4.19 at lGHz. Above lGHz, its DK value changes gently. For example, under l0GHz, the DK value of FR-4 is 4.15. For substrate materials with high speed and high frequency characteristics, the DK value changes slightly. From lMHz to lGHz, the DK value mostly stays within 0.02 range. The DK value tends to decrease slightly at different frequencies from low to high.

The dielectric loss factor (DF) of the general substrate material is larger than that of DK due to the influence of frequency variation (especially in the high frequency range). Při hodnocení vysokofrekvenčních charakteristik substrátového materiálu bychom se proto měli zaměřit na změnu jeho hodnoty DF. The substrate materials with high speed and high frequency characteristics are obviously different from the general substrate materials in terms of the variation characteristics at high frequency. One is that with the change of frequency, its (DF) value changes very little. Druhý je podobný obecnému substrátovému materiálu v rozsahu variací, ale jeho vlastní (DF) hodnota je nižší.

How to choose high frequency high speed plate

Výběr desek plošných spojů musí splňovat konstrukční požadavky, sériovou výrobu a náklady na rovnováhu mezi nimi. In short, the design requirements consist of two components: electrical and structural reliability. This is usually important when designing very high speed PCB boards (frequencies greater than GHz). For example, the fr-4 material commonly used today may not be applicable due to its large Df (Dielectricloss) at several GHz frequencies.

Jaké jsou vysokofrekvenční desky PCB? Vysokofrekvenční klasifikace desek plošných spojů

For example, a 10Gb/S high-speed digital signal is a square wave, which can be regarded as a superposition of sinusoidal signals of different frequencies. Therefore, 10Gb/S contains many different frequency signals: 5Ghz fundamental signal, 3 order 15GHz, 5 order 25GHz, 7 order 35GHz signal, etc. The integrity of the digital signal and the steepness of the upper and lower edges are the same as the low loss and low distortion transmission of rf microwave (the high frequency harmonic part of the digital signal reaches the microwave band). Therefore, in many respects, the PCB material selection of high-speed digital circuits is similar to the requirements of RF microwave circuits.

Jaké jsou vysokofrekvenční desky PCB? Vysokofrekvenční klasifikace desek plošných spojů

In practical engineering operations, the selection of high-frequency plates seems simple, but there are still many factors to be considered. Through the introduction of this paper, AS a PCB design engineer or a high-speed project leader, I have a certain understanding of the characteristics and selection of plates. Pochopte elektrické vlastnosti, tepelné vlastnosti, spolehlivost atd. And rational use of stacking, design a piece of high reliability, good processing products, various factors to consider the best.

Následující text představí hlavní faktory, které je třeba při výběru vhodné desky zvážit:

1, vyrobitelnost:

Několikanásobný lisovací výkon, teplotní výkon, odolnost vůči CAF/ teplu a mechanická houževnatost (viskozita) (dobrá spolehlivost), požární odolnost;

2, with the product matching performance (electrical, performance stability, etc.) :

Nízké ztráty, stabilní parametry Dk/Df, nízká disperze, malý koeficient změny frekvence a prostředí, malá tolerance tloušťky materiálu a obsahu gumy (dobrá kontrola impedance), pokud je vodič dlouhý, zvažte měděnou fólii s nízkou drsností. In addition, simulation is needed in the early stage of high-speed circuit design, and simulation results are the reference standard for design. „Společná laboratoř Xingsen Technology-Agilent (vysokorychlostní/RADIO frekvence) vyřešila problém s výkonem nekonzistentních výsledků simulace a testů a provedla velký počet simulací a skutečných testů s uzavřenou smyčkou, a to prostřednictvím jedinečné metody k dosažení konzistence simulace a měření.

Jaké jsou vysokofrekvenční desky PCB? Vysokofrekvenční klasifikace desek plošných spojů

3. Timely availability of materials:

Many high-frequency plate procurement cycle is very long, even 2-3 months; In addition to the conventional high frequency plate RO4350 has inventory, many high frequency plates need to be provided by customers. Therefore, high frequency plate and manufacturers need to communicate well in advance, as soon as possible;

4. Nákladové faktory:

Depending on the price sensitivity of the product, whether it is a consumer product, or a telecommunications, medical, industrial, military application;

5. Applicability of laws and regulations, etc.

Aby byla kompatibilní s ekologickými předpisy v různých zemích a splňovala požadavky RoHS a bezhalogenová.

Among the above factors, the running speed of high-speed digital circuit is the main factor to consider in PCB selection. The higher the circuit speed, the smaller the selected PCBDf value should be. Obvodová deska se střední a nízkou ztrátou bude vhodná pro digitální obvod 10 Gb/S; The plate with lower loss is suitable for 25Gb/s digital circuit; Panely s extrémně nízkou ztrátou pojmou rychlejší, vysokorychlostní digitální obvody rychlostí 50 Gb/s nebo vyšší.

From the material Df:

Df mezi obvodovou deskou 0.01 ~ 0.005 vhodnou pro horní hranici digitálního obvodu 10 Gb/S;

Df mezi obvodovou deskou 0.005 ~ 0.003 vhodnou pro horní hranici digitálního obvodu 25 Gb/S;

Circuit boards with Df not more than 0.0015 are suitable for 50Gb/S or higher speed digital circuits.

Commonly used high-speed plates are:

1), Rogers: RO4003, RO3003, RO4350, RO5880, etc

2), Taiyao TUC:Tuc862, 872SLK, 883, 933, etc

3), Panasonic: Megtron4, Megtron6, etc

4), Isola: FR408HR, IS620, IS680 atd

5) Nelco: N4000-13, N4000-13EPSI, etc

6), Dongguan Shengyi, Taizhou Wangling, mikrovlnná trouba Taixing atd