Txhais ntawm high-frequency PCB board

Lub rooj tsav xwm siab hais txog lub tshuab hluav taws xob hluav taws xob tshwj xeeb tshwj xeeb, siv ntau zaus (ntau dua 300 MHZ zaus lossis nthwv dej tsawg dua 1 meter) thiab microwave (ntau dua 3 GHZ zaus lossis nthwv dej tsawg dua 0.1 meters) hauv thaj tsam ntawm PCB, yog nyob ntawm microwave puag tooj tooj liab clad siv cov khoom siv nruj hauv Circuit Court tsim cov txheej txheem ntawm ib feem ntawm cov txheej txheem lossis kev siv cov txheej txheem tshwj xeeb thiab tsim cov laug cam. Feem ntau, cov laug cam siab tuaj yeem txhais tau tias yog cov laug cam nrog cov zaus ntau dua 1GHz.

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. Piv txwv li, cov khoom siv hauv substrate yuav tsum muaj cov khoom siv hluav taws xob zoo, muaj kev ruaj ntseg zoo, nrog rau kev nce lub zog teeb liab zaus hauv cov txheej txheem poob qis yog qhov tsawg heev, yog li qhov tseem ceeb ntawm cov phaj siab tau qhia.

Classification of PCB high frequency plate

1, at the end of the ceramic filled thermosetting material

Ua txoj kev:

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. PTFE (polytetrafluoroethylene) khoom

Ua txoj kev:

1. Cov khoom qhib: tiv thaiv zaj duab xis yuav tsum tau khaws cia kom tiv thaiv khawb thiab khawb

2. Laum:

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

2.2 Aluminium ntawv raws li cov phaj npog, tom qab ntawd siv 1 hli tuab amine phaj, ua kom nruj cov phaj PTFE

2.3 Tshuab cov plua plav tawm ntawm lub qhov nrog rab phom cua tom qab siv dej tas

2.4 Nrog rau qhov ruaj khov tshaj plaws drilling rig, ntsuas tsis tau (qhov tseeb, qhov me dua, qhov nrawm dua qhov drilling, qhov me dua Chip load, qhov me dua qhov rov qab los)

3. Lub qhov ua

Kev kho ntshav los yog sodium – naphthalene qhib kev kho yog muaj txiaj ntsig zoo rau kev ua kom cov xim pores

4. PTH tog tooj liab

4.1 Tom qab micro-etching (micro-etching tus nqi tau tswj los ntawm 20 micro-ntiv tes), phaj tau pub los ntawm cov roj tshem lub tog raj kheej hauv PTH rub

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:

Dab tsi yog PCB cov laug cam ntau zaus? Kev faib tawm cov phaj siab hauv PCB

Cov khoom siv siab thiab siab ceev ntawv

Thaum xaiv lub substrate rau PCB rau kev siv hluav taws xob ntau zaus, kev txiav txim siab tshwj xeeb yuav tsum tau muab rau cov yam ntxwv sib txawv ntawm cov khoom DK ntawm ntau zaus. 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. Tshwj xeeb tshaj yog nyob hauv ntau zaus los ntawm L MHz txog L GHz, lawv DK thiab DF qhov txiaj ntsig hloov pauv ntau dua. 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. Saum toj no lGHz, nws DK tus nqi hloov maj mam. 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.

Qhov dielectric poob qhov (DF) ntawm cov khoom siv dav dav yog qhov loj dua li ntawm DK vim qhov cuam tshuam ntawm kev hloov pauv ntau zaus (tshwj xeeb yog hauv qhov ntau zaus). Yog li ntawd, thaum ntsuas qhov ua haujlwm siab yam ntxwv ntawm cov khoom siv substrate, peb yuav tsum tsom mus rau qhov kev hloov pauv ntawm nws tus nqi DF. Cov khoom siv substrate nrog kev kub ceev thiab cov yam ntxwv ua haujlwm siab yog qhov sib txawv ntawm cov khoom siv dav hauv cov ntsiab lus ntawm cov yam ntxwv sib txawv ntawm qhov siab. Ib qho yog tias nrog kev hloov pauv zaus, nws (DF) tus nqi hloov pauv tsawg heev. Lwm qhov zoo ib yam li cov khoom siv dav dav hauv ntau qhov kev hloov pauv, tab sis nws tus kheej (DF) tus nqi qis dua.

How to choose high frequency high speed plate

Kev xaiv PCB pawg thawj coj yuav tsum ua kom tau raws li qhov xav tau tsim, kev tsim khoom ntau thiab tus nqi ntawm qhov sib npaug. 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.

Dab tsi yog PCB cov laug cam ntau zaus? Kev faib tawm cov phaj siab hauv PCB

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. Kev ntseeg siab ntawm lub teeb liab digital thiab qhov tob ntawm sab saud thiab qis dua yog zoo ib yam li qhov poob qis thiab kev hloov pauv tsis sib xws ntawm rf microwave (qhov ntau zaus sib raug zoo ib feem ntawm cov teeb liab digital mus txog microwave band). Therefore, in many respects, the PCB material selection of high-speed digital circuits is similar to the requirements of RF microwave circuits.

Dab tsi yog PCB cov laug cam ntau zaus? Kev faib tawm cov phaj siab hauv PCB

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. Nkag siab txog cov khoom siv hluav taws xob, cov khoom siv cua sov, kev ntseeg tau, thiab lwm yam. And rational use of stacking, design a piece of high reliability, good processing products, various factors to consider the best.

Cov hauv qab no yuav qhia txog yam tseem ceeb los txiav txim siab xaiv lub phaj uas tsim nyog:

1, kev tsim khoom:

Xws li kev ua haujlwm ntau yam nias, ua haujlwm kub, CAF/ tshav kub thiab lub zog ua haujlwm (viscosity) (ntseeg tau zoo), ntsuas hluav taws;

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

Tsawg poob, ruaj khov Dk/Df tsis, kev faib qis, hloov pauv me me nrog zaus thiab ib puag ncig, kev ua siab ntev me me ntawm cov khoom tuab thiab cov ntsiab lus roj hmab (tiv thaiv kev tiv thaiv zoo), yog tias xaim ntev, txiav txim siab qis qis tooj liab. In addition, simulation is needed in the early stage of high-speed circuit design, and simulation results are the reference standard for design. “Xingsen Technology-Agilent (kev kub ceev/RADIO zaus) Kev sib koom ua ke” daws qhov teeb meem kev ua haujlwm ntawm kev sim ua tsis sib xws thiab ntsuas, thiab tau ua ntau qhov simulation thiab qhov kev sim kaw kaw lub voj pov thawj, los ntawm txoj hauv kev tshwj xeeb kom ua tiav qhov sib xws. simulation thiab ntsuas.

Dab tsi yog PCB cov laug cam ntau zaus? Kev faib tawm cov phaj siab hauv PCB

3. Cov khoom siv raws sijhawm:

Ntau lub phaj ua khoom siv ntau lub voj voog ntev heev, txawm tias 2-3 lub hlis; 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. Cov nuj nqis:

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.

Txhawm rau ua tau raws li kev cai ib puag ncig ntawm ntau lub tebchaws thiab ua tau raws li qhov yuav tsum tau ua ntawm RoHS thiab tsis muaj halogen.

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. Cov phaj hluav taws xob nrog nruab nrab thiab poob qis yuav haum rau 10Gb/S digital Circuit; The plate with lower loss is suitable for 25Gb/s digital circuit; Panels nrog qhov poob qis tshaj yuav ua kom nrawm dua, ua kom nrawm nrawm digital ntawm tus nqi 50Gb/s lossis siab dua.

From the material Df:

Df nruab nrab ntawm 0.01 ~ 0.005 lub rooj sib tham tsim nyog rau qhov txwv qis tshaj ntawm 10Gb/S digital Circuit;

Df nruab nrab ntawm 0.005 ~ 0.003 lub rooj sib tham tsim nyog rau qhov txwv qis tshaj ntawm 25Gb/S digital Circuit;

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, thiab lwm yam

3), Panasonic: Megtron4, Megtron6, etc

4), Isola: FR408HR, IS620, IS680, thiab lwm yam

5) Nelco: N4000-13, N4000-13EPSI, thiab lwm yam

6), Dongguan Shengyi, Taizhou Wangling, Taixing Microwave, thiab lwm yam