The interconnect of papan sirkuit cetak sistem kalebu papan chip-to-circuit, sambung ing PCB lan sambung antarane PCB lan piranti eksternal. In RF design, the electromagnetic characteristics at the interconnect point is one of the main problems faced by engineering design. This paper introduces various techniques of the above three types of interconnect design, including device installation methods, isolation of wiring and measures to reduce lead inductance.

Ana pratandha manawa papan sirkuit cetak lagi dirancang kanthi frekuensi. As data rates continue to increase, the bandwidth required for data transmission also pushes the signal frequency ceiling to 1GHz or higher. This high frequency signal technology, although far beyond the millimeter wave technology (30GHz), does involve RF and low-end microwave technology.

Metode desain rekayasa RF kudu bisa ngatasi efek lapangan elektromagnetik sing luwih kuat sing umume digawe kanthi frekuensi sing luwih dhuwur. Bidang elektromagnetik iki bisa ngindhuksi sinyal ing garis sinyal utawa garis PCB sing jejer, nyebabake crosstalk (gangguan lan gangguan total) lan kinerja sistem sing ngrusak. Backloss is mainly caused by impedance mismatch, which has the same effect on the signal as additive noise and interference.

High return loss has two negative effects: 1. The signal reflected back to the signal source will increase the noise of the system, making it more difficult for the receiver to distinguish noise from signal; 2. 2. Sembarang sinyal sing dibayangke intine bakal ngrusak kualitas sinyal amarga bentuk sinyal input ganti.

Sanajan sistem digital sabar banget amarga mung menehi sinyal 1 lan 0, harmoni sing digawe nalika denyut nadi kanthi kacepetan dhuwur nyebabake sinyal dadi luwih lemah ing frekuensi sing luwih dhuwur. Sanajan koreksi kesalahan maju bisa ngilangi sawetara efek negatif, bagean saka bandwidth sistem digunakake kanggo ngirim data sing keluwih, nyebabake degradasi kinerja. Solusi sing luwih apik yaiku efek RF sing mbantu, tinimbang ora integritas sinyal. Disaranake supaya total kerugian ing frekuensi paling dhuwur saka sistem digital (biasane titik data sing ora apik) dadi -25dB, padha karo VSWR 1.1.

Desain PCB tujuane luwih cilik, luwih cepet lan luwih murah. Kanggo RFPCB, sinyal kacepetan dhuwur kadang-kadang matesi miniaturisasi desain PCB. Saiki, cara utama kanggo ngatasi masalah crosseration yaiku nindakake manajemen sambungan dhasar, nindakake jarak antarane kabel lan nyuda induktansi timah. Cara utama kanggo nyuda rugi bali yaiku pencocokan impedansi. Cara iki kalebu manajemen efektif bahan jampel lan isolasi garis sinyal aktif lan garis dhasar, utamane ing antarane kahanan garis sinyal lan lemah.

Amarga interkoneksi minangka link paling ringkih ing rantai sirkuit, ing desain RF, sifat elektromagnetik saka titik interkoneksi minangka masalah utama sing diadhepi desain rekayasa, saben titik interkoneksi kudu diselidiki lan masalah sing wis ana ditanggulangi. Hubungan papan sirkuit kalebu interkoneksi papan chip-to-circuit, interkoneksi PCB lan interput sambungan input / output antarane PCB lan piranti eksternal.

I. Hubungan antara chip lan papan PCB

Apa solusi iki bisa digunakake, ora jelas, para pamiarsa manawa teknologi desain IC adoh banget karo teknologi desain PCB kanggo aplikasi hf.

PCB sambung sambung

Teknik lan metode desain hf PCB kaya ing ngisor iki:

1. Sudut 45 ° kudu digunakake kanggo sudhut garis transmisi kanggo nyuda kerugian bali (Gambar 1);

2 nilai pancet jampel miturut level papan sirkuit isolasi kinerja tinggi sing dikontrol. Cara iki migunani kanggo manajemen lapangan elektromagnetik sing efektif ing antarane bahan insulasi lan kabel sing ana ing jejere.

3. Spesifikasi desain PCB kanggo etching presisi tinggi kudu ditambah. Coba nemtokake kesalahan jembar baris total +/- 0.0007 inci, ngatur bagean bagean ngisor lan salib saka bentuk kabel lan nemtokake kahanan plating tembok sisih kabel. Overall management of wiring (wire) geometry and coating surfaces is important to address skin effects related to microwave frequencies and to implement these specifications.

4. Ana induktansi tunyuk ing arah sing nonjol. Aja nggunakake komponen kanthi lead. Kanggo lingkungan frekuensi dhuwur, luwih becik nggunakake komponen sing dipasang ing permukaan.

5. Kanggo sinyal liwat bolongan, aja nggunakake proses PTH ing piring sensitif, amarga proses iki bisa nyebabake induktansi timbal ing bolongan liwat. Lead inductance can affect layers 4 to 19 if a through-hole in a 20-ply board is used to connect layers 1 to 3.

6. Nyedhiyakake lapisan lemah sing akeh. Moulded holes are used to connect these grounding layers to prevent 3d electromagnetic fields from affecting the circuit board.

7. Kanggo milih plating nikel non-elektrolisis utawa proses plating emas perendaman, aja nggunakake metode plating HASL. Lumahing electroplated iki nyedhiyakake efek kulit sing luwih apik kanggo arus frekuensi tinggi (Gambar 2). In addition, this highly weldable coating requires fewer leads, helping to reduce environmental pollution.

8. Solder resistance layer can prevent solder paste from flowing. Nanging, amarga ora yakin kekandelan lan kinerja insulasi sing ora dingerteni, nutupi kabeh permukaan piring kanthi bahan resistensi solder bakal nyebabake pangowahan energi elektromagnetik sing gedhe ing desain mikrostrip. Generally, solderdam is used as welding resistance layer.

Yen sampeyan ora ngerti cara iki, konsultasi karo insinyur desain berpengalaman sing wis makarya ing papan sirkuit gelombang mikro kanggo militer. You can also discuss with them what price range you can afford. Contone, luwih irit nggunakake desain mikrostrip sing didukung tembaga tinimbang desain garis garis, lan sampeyan bisa ngrembug babagan iki kanggo njaluk saran sing luwih apik. Insinyur sing apik bisa uga ora biasa mikir babagan biaya, nanging saranane bisa migunani banget. Bakal dadi tugas jangka panjang kanggo nglatih para insinyur enom sing ora kenal karo efek RF lan ora duwe pengalaman nalika ngatasi efek RF.

Kajaba iku, solusi liyane bisa digunakake, kayata nambah model komputer supaya bisa ngatasi efek RF.

PCB sambungake karo piranti eksternal

Saiki kita bisa nganggep manawa kita wis ngatasi kabeh masalah manajemen sinyal ing papan lan interkoneksi komponen diskrit. Dadi, kepiye carane ngatasi masalah input / output sinyal saka papan sirkuit menyang kabel sing nyambungake piranti remot? TrompeterElectronics, sawijining inovator teknologi kabel koaksial, ngupayakake masalah iki lan wis nggawe kemajuan penting (gambar 3). Also, take a look at the electromagnetic field shown in Figure 4 below. Ing kasus iki, kita ngatur konversi saka mikrostrip menyang kabel koaksial. Ing kabel koaksial, lapisan lemah dipasang ing cincin lan jarak sing rata. Ing microbelts, lapisan grounding ana ing sangisore garis aktif. Iki ngenalake efek pinggiran tartamtu sing kudu dingerteni, diprediksi, lan dipertimbangkan nalika desain. Mesthine, ketidakcocokan iki uga bisa nyebabake mundur lan kudu minimalake supaya ora ana gangguan swara lan sinyal.

Manajemen masalah impedansi internal dudu masalah desain sing bisa diabaikan. Impedansi diwiwiti ing permukaan papan sirkuit, ngliwati sendi solder menyang sendi, lan pungkasane ana ing kabel koaksial. Amarga impedansi beda-beda gumantung karo frekuensi, frekuensi sing luwih dhuwur, manajemen impedansi sing luwih angel. The problem of using higher frequencies to transmit signals over broadband appears to be the main design problem.