PCB部落格 - PCB接線完成後要檢查的項目

1 PCB電路板 design inspection
The following checklist covers all aspects of the design cycle, 特殊應用的附加項目. 全體的 PCB板 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, 大面積銅箔是否打開?
12) Whether there is a tool positioning hole;

2. PCB板 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. PCB板 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 震驚 and 振動 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. PCB板 mechanical design factors
Although the printed board supports components mechanically, 它不能用作整個設備的結構部分. 印版邊緣, 至少每5英寸一次，以獲得一定的支撐力. 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, 比如散熱, 通風, shock, vibration, 濕度. 灰塵, 鹽霧和輻射.
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. 根據實踐經驗, 厚度為0的印製板支撐點間距.031-0.062英寸應至少為4英寸； 對於厚度大於0的印製板.093英寸, 支撐點的間距應至少為4英寸. 5英寸. 採取此措施會新增印製板的剛度，並破壞印製板可能的共振. 在决定其安裝科技之前，印製板通常必須考慮以下因素.
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, 尤其是它的尺寸應該考慮在內.
5) A plug-in device is required, 通常用鉚釘固定在印製板組件上.
6) In the mounting frame of the printed board, 需要特殊設計，如承重法蘭.
7) The adaptability of the plugging tools used to the size, 印製板的形狀和厚度.
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, 要求在一定程度上能够進入設備內部.

7. PCB板 mechanical considerations
Substrate properties that have a significant impact on printed circuit assemblies are: water absorption, 熱膨脹係數, 熱效能, 彎曲強度, 衝擊強度, 抗拉强度, 剪切强度和硬度. 所有這些特性都會影響印製板結構的功能和印製板結構的生產率. 對於大多數應用程序, 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.
每個基材可以是阻燃的或可燃的. 以上1, 2, 3可穿孔. 金屬化孔印製板常用的資料是環氧玻璃布. 其尺寸穩定性適用於高密度電路, 並且可以减少金屬化孔中裂紋的發生. 環氧玻璃布層壓板的一個缺點是難以在印製板的通常厚度範圍內衝壓, 囙此，通常鑽所有孔，並使用複製銑削操作來形成印製板形狀.

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.
關鍵阻抗組件或高頻組件通常緊密放置在一起，以减少關鍵階段延遲. 變壓器和感應組件應隔離，以防止耦合； 感應訊號線應以直角正交敷設； 應隔離或牢固安裝因磁場運動產生任何電雜訊的部件，以防止過度振動.

9. PCB板 導線模式 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, 導線和安裝孔之間, 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 PCB板 wire pattern.