PCB新聞 - PCB設計中防靜電放電的PCB防護方法

在PCB打樣設計中, 防靜電放電 PCB的設計 可以通過分層實現, 正確佈局和安裝. 在設計過程中, 絕大多數設計修改可以限制為通過預測添加或减少組件. 通過調整 PCB板 佈局和佈線, ESD可以很好地預防. 以下是一些常見的預防措施.

*Use multi-layer PCBs as much as possible. 與雙面PCB相比, 地平面和電源平面, 以及緊密排列的訊號線接地間距可以减少共模阻抗和電感耦合, 使其達到雙面PCB的水准. /10比1/100. 儘量使每個訊號層靠近電源層或接地層. 對於頂部和底部表面有元件的高密度PCB, 短連接線, 和許多填充, 可以考慮使用內層線.
*For PCB proofing, 應使用緊密交織的電源和接地網. 電源線靠近地線, 以及垂直線和水平線或填充區域之間盡可能多的連接. 一側網格尺寸小於或等於60mm. 如果可能的話, 網格尺寸應小於13mm.
*Ensure that each circuit is as compact as possible.
* Put all the connectors aside as much as possible.
*If possible, 從卡的中心引入電源線，遠離直接受靜電放電影響的區域.
*On all PCB layers below the connector that leads to the outside of the chassis (easy to be directly hit by ESD), 放置較寬的底盤地面或多邊形填充地面, 並在約13mm的距離處用過孔將其連接在一起. .
*Place mounting holes on the edge of the card, 並將安裝孔周圍無阻焊劑的頂部和底部焊盤連接至底盤接地.
在樣品組裝過程中，請勿在PCB頂部或底部的焊盤上塗抹任何焊料. 使用帶有內寘墊圈的螺釘，以實現PCB和金屬主機殼之間的緊密接觸/遮罩層或地平面上的支架.
*The same "isolation zone" should be set between the chassis ground and circuit ground on each layer; if possible, 保持間距為0.64毫米.
* At the top and bottom layers of the card near the mounting holes, 用1連接底盤接地和電路接地.沿底盤接地線每隔100mm有27mm寬的電線. 靠近這些連接點, 在主機殼接地和電路接地之間放置用於安裝的襯墊或安裝孔. 可以用刀片切斷這些接地連接，以保持電路開路, 或帶有磁珠的跳線/高頻電容器.
*If the PCB proofing will not be placed in a metal chassis or shielding device, 電路板的頂部和底部底盤地線不能使用阻焊劑, 囙此，它們可以用作靜電放電電弧的放電電極.
* To set a ring ground around the circuit in the following way:
(1) In addition to the edge connector and the chassis ground, 在整個週邊周圍放置一個圓形接地路徑.
(2) Ensure that the ring ground width of all layers is greater than 2.5毫米.
(3) Connect circularly with via holes every 13mm.
(4) Connect the ring ground to the common ground of the 多層電路.
(5) For double panels installed in metal cases or shielding devices, 環形接地應連接到電路的公共接地. 對於非遮罩雙面電路, 環形接地應連接至底盤接地. 阻焊劑不應用於環接地, 囙此，環形接地可以作為ESD放電棒. Place at least one at a certain position on the ring ground (all layers) 0.5毫米寬間隙, 所以你可以避免形成一個大的迴圈. 訊號線和環形接地之間的距離不應小於0.5mm.
* In areas that can be directly hit by ESD, 必須在每個訊號線附近放置接地線.
*The I/O電路應盡可能靠近相應的連接器.
*For circuits that are susceptible to ESD, 它們應放置在電路中心附近, 囙此其他電路可以為其提供一定的遮罩效果.
* Generally, 串聯電阻器和磁珠放置在接收端. 對於那些容易受到靜電放電影響的電纜驅動程序, 您也可以考慮在驅動端放置串聯電阻或磁珠.
*Usually place a transient protector at the receiving end. Use a short and thick wire (length less than 5 times the width, preferably less than 3 times the width) to connect to the chassis ground. 連接器的訊號線和地線應直接連接到瞬態保護器，然後再連接到電路的其他部分.
*Place a filter capacitor at the connector or within 25mm from the receiving circuit.
(1) Use a short and thick wire to connect to the chassis ground or the receiving circuit ground (the length is less than 5 times the width, preferably less than 3 times the width).
(2) The signal wire and ground wire are connected to the capacitor first and then to the receiving circuit.
*Make sure that the signal line is as short as possible.
* When the length of the signal wire is greater than 300mm, 接地線必須平行敷設.
* Ensure that the loop area between the signal line and the corresponding loop is as small as possible. 對於長訊號線, 訊號線和地線的位置必須每隔幾釐米交換一次，以减少環路面積.
* Drive signals from the center of the network into multiple receiving circuits.
*Ensure that the loop area between the power supply and the ground is as small as possible, 並在集成電路晶片的每個電源引脚附近放置高頻電容器.
*Place a high-frequency bypass capacitor within 80mm of each connector.
* Where possible, 用土地填充未使用的區域, 並每隔60mm連接各層填土.
* Make sure to connect with the ground at the two opposite end positions of an arbitrarily large ground filling area (about greater than 25mm*6mm).
* When the length of the opening on the power supply or ground plane exceeds 8mm, 使用窄線連接開口的兩側.
*The reset line, 中斷訊號線或邊緣觸發訊號線不能佈置在靠近PCB邊緣的位置.
*Connect the mounting holes to the circuit common ground, 或者隔離他們.
(1) When the metal bracket must be used with a metal shielding device or a chassis, 應使用零歐姆電阻來實現連接.
(2) Determine the size of the mounting hole to achieve reliable installation of metal or plastic brackets. 在安裝孔的頂層和底層使用大墊子, 並且底部焊盤上不能使用阻焊劑, 並確保底部焊盤不使用波峰焊接技術. 焊接.
*The protected signal line and the unprotected signal line cannot be arranged in parallel.
* Pay special attention to the wiring of reset, 中斷和控制訊號線.
(1) High frequency filtering should be used.
(2) Keep away from input and output circuits.
(3) Keep away from the edge of the circuit board.
PCB打樣應插入外殼中, 未安裝在開口位置或內縫.