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Items to be checked after PCB wiring is completed
Blog PCB
Items to be checked after PCB wiring is completed

Items to be checked after PCB wiring is completed

2022-04-25
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Author:pcb

1. Papan PCB design inspection
The following checklist covers all aspects of the design cycle, dengan item tambahan untuk aplikasi istimewa:. Jeneral Papan PCB design drawing inspection items:
1) The circuit is analyzed or not, and the circuit is divided into basic units in order to smooth the signal;
2) Whether the circuit allows the use of short or isolated key leads;
3) Where must be shielded, whether it is effectively shielded;
4) Make full use of the basic grid graphics without;
5) Whether the size of the printed board is the size;
6) Whether to use the selected wire width and spacing as much as possible;
7) Whether the preferred pad size and hole size are used;
8) Whether the photographic plate and sketch are suitable;
9) Whether there are few jumper wires used; whether the jumper wires should pass through components and accessories;
10) Whether the letters are visible after assembly; whether their size and model are correct;
11) In order to prevent blistering, adalah kawasan besar foil tembaga terbuka?
12) Whether there is a tool positioning hole;

Papan PCB

2. Papan PCB electrical characteristics inspection items
1) Whether the influence of wire resistance, inductance and capacitance has been analyzed; especially the influence of the key voltage drop to grounding;
2) Whether the spacing and shape of the wire accessories meet the insulation requirements;
3) Whether the insulation resistance value is controlled and specified at key points;
4) Whether the polarity is adequately identified;
5) The influence of wire spacing on leakage resistance and voltage was measured from the geometrical point of view;
6) Whether the medium that changes the surface coating has been identified;

3. Papan PCB physical characteristics inspection items
1) Whether all pads and their positions are suitable for final assembly;
2) Whether the assembled printed board can meet the shock and getaran power conditions;
3) What is the spacing of the specified standard components;
4) Whether the components that are not firmly installed or the heavier parts are fixed well;
5) Whether the heat dissipation and cooling of the heating element are correct; or whether it is isolated from the printed board and other thermal elements;
6) Whether the voltage divider and other multi-lead components are positioned correctly;
7) Component arrangement and orientation for easy inspection;
8) Whether all possible interference on the printed board and the entire printed board assembly has been eliminated;
9) Whether the size of the positioning hole is correct;
10) Whether the tolerance is complete and reasonable;
11) Control and sign off the physical properties of all coatings;
12) Whether the ratio of the diameter of the hole to the lead wire is within the acceptable range;

4. Papan PCB mechanical design factors
Although the printed board supports components mechanically, ia tidak boleh digunakan sebagai bahagian struktur seluruh peranti. Di tepi piring cetakan, sekurang-kurangnya setiap 5 inci untuk jumlah sokongan tertentu. The factors that must be considered in the selection and design of printed boards are as follows;
1) The structure of the printed board - size and shape.
2) The type of mechanical accessories and plugs (seats) required.
3) The adaptability of the circuit to other circuits and environmental conditions.
4) Consider mounting the printed board vertically or horizontally depending on factors such as heat and dust.
5) Some environmental factors that need special attention, seperti penyebaran panas, ventilasi, shock, vibration, weather forecast. Dust, semburan garam dan radiasi.
6) Degree of support.
7) Hold and fix.
8) Easy to take off.

5. Installation requirements for printed circuit boards
It should be supported at least within 1 inch of the three edge edges of the printed board. Menurut pengalaman praktik, jarak titik sokongan papan dicetak dengan tebal 0.031-0.062 inci sepatutnya sekurang-kurangnya 4 inci; untuk papan cetak dengan tebal lebih dari 0.093 inci, jarak titik sokongan sepatutnya sekurang-kurangnya 4 inci. 5 inci. Mengambil tindakan ini meningkatkan ketat papan cetak dan menghancurkan resonans yang mungkin papan cetak. Papan cetak biasanya perlu mempertimbangkan faktor berikut sebelum memutuskan teknologi pemasangan.
1) The size and shape of the printed board.
2) Number of input and output terminals.
3) The available equipment space.
4) Desired ease of loading and unloading.
5) The type of installation accessories.
6) The required heat dissipation.
7) Required shieldability.
8) The type of circuit and its relationship with other circuits.

6. Dial-out requirements for printed boards
1) No printed board area for mounting components.
2) The influence of plugging tools on the installation distance between two printed boards.
3) The mounting holes and slots should be specially prepared in the design of the printed board.
4) When the plug-in tool is to be used in the equipment, terutama saiz patut dianggap.
5) A plug-in device is required, yang biasanya ditetapkan pada kumpulan papan cetak dengan rivet.
6) In the mounting frame of the printed board, reka-reka istimewa seperti lengan pembawa muatan diperlukan.
7) The adaptability of the plugging tools used to the size, bentuk dan tebal papan cetak.
8) The cost involved in using plugging and unplugging tools includes both the price of the tool and the increased expenditure.
9) In order to tighten and use plug-in tools, ia diperlukan untuk mempunyai akses ke dalam peralatan.

7. Papan PCB mechanical considerations
Substrate properties that have a significant impact on printed circuit assemblies are: water absorption, koeficient pengembangan panas, ciri-ciri panas, kekuatan fleksiral, kekuatan kesan, tensil strength, kekuatan dan kesukaran. Semua ciri-ciri ini mempengaruhi kedua-dua fungsi struktur papan cetak dan produktifiti struktur papan cetak. Untuk kebanyakan aplikasi, the printed circuit board's dielectric backing is one of the following:
1) Phenolic impregnated paper.
2) Acrylic-polyester impregnated glass mats with random arrangement.
3) Epoxy impregnated paper.
4) Epoxy impregnated glass cloth.
Setiap substrat boleh menjadi penambah api atau boleh terbakar. Yang di atas 1, 2, 3 boleh ditembak. Bahan yang biasa digunakan untuk papan cetak lubang metalisasi adalah kain kaca epoksi. Kestabilan dimensi adalah sesuai untuk sirkuit densiti tinggi, dan ia boleh mengurangkan kejadian retak dalam lubang metalisasi. Salah satu kelemahan dari laminat kain kaca epoksi adalah bahawa ia sukar untuk ditembak dalam julat tebal biasa papan cetak, untuk sebab ini semua lubang biasanya dibuang dan operasi pembuat salinan digunakan untuk membentuk bentuk papan cetak.

8. PCB wire spacing
The conductors must be spaced to eliminate voltage breakdown or arcing between adjacent conductors. Spacing is variable and depends primarily on the following factors:
1) Peak voltage between adjacent wires.
2) Atmospheric pressure (working height).
3) Coating layer used.
4) Capacitive coupling parameters.
Komponen impedance kritik atau komponen frekuensi tinggi biasanya ditempatkan dekat bersama untuk mengurangi lambat tahap kritik. Penukar dan komponen induktif patut diasingkan untuk mencegah sambungan; wayar isyarat induktif patut dijalankan secara ortogonal pada sudut kanan; komponen yang menghasilkan sebarang bunyi elektrik disebabkan gerakan medan magnetik seharusnya diasingkan atau diletak tegak untuk mencegah getaran berlebihan.

9. Papan PCB corak wayar inspection
1) Whether the wire is short and straight without sacrificing function;
2) Whether the limitation of wire width is complied with;
3) Check whether the distance between wires, antara wayar dan lubang lekap, and between wires and pads must be guaranteed;
4) Whether the parallel arrangement of all wires (including component leads) is relatively close is avoided;
5) Whether acute angles (90°C or less) are avoided in the Papan PCB wire pattern.