PCB beskyttelsestype

I de enkleste termer kan PCB -fastholdelse defineres som følger:

En PCB -ledningsramme er designet af designeren til eksterne komponenter i områder, der ikke er opsat på printkortet, hvor kobberspor eller andre printkortkomponenter skal komme ind eller krydse. The area can be or contain copper and can be of any shape.

In most cases, retention zones are used to keep certain board areas far enough away from other components to prevent or minimize EMI. However, they are also used to provide spacing for fan-out tracing of surface-mounted components. Eksempler er processorer eller FPGas, som normalt er PCB -evaluerings- og udviklingstavler. Some common reservation types are listed below.

Type of PCB protection

L antenna

Probably, the most common type of reservation is to reserve an area of copper wire around an onboard or connected antenna to prevent EMI from affecting the fidelity of the transmitted or received signal. Reservationer kan også indeholde antenneledninger til andre kredsløb.

L parts

It is also common to make room for fan-outs around components (especially EM radiators). This is true for microprocessors, FPgas, AFE and other medium to high pin count components (commonly used for patch packages).

L Pladekantfrigangsområde

Kantfrigang er meget vigtig i fremstillingen. Specifically, panels are split into individual boards during PCB assembly. To do this, enough clearance must be left for wiring or scoring.

L sporing

Sometimes it may be advantageous to define reservation areas around traces. Nogle gange brugt til koplanære jordforbundne transmissionslinjer for at opnå kontrolleret impedans.

L drilling

Many plates are installed by screws or bolts. In these cases, it is helpful to define the spacing around the holes. Insufficient spacing can affect assembly, interrupt circuit operation, and even cause circuit board damage. For gennemgående huller følger du normalt bare CM’s DFM-regler.

L-stik

Depending on the connector type in terms of layout and placement, your board design may need to consider two considerations: the footprint of the connector board and the paneling. Normalt inkluderer layoutet af stikket eller stikket ikke plads til eksterne ledninger eller kabelforbindelser. In these cases, maintaining state is important to ensure that the circuit actually performs as expected.

L switch

Another good use of reserve is to provide room to flip or move horizontally mounted switches.

Ovenstående liste giver nogle almindelige typer og anvendelser til PCB -fastholdelse. In other cases, however, you may need to define reserved areas. For eksempel, hvis dit design bruger komponenter; For example, in operational amplifiers, where there is a large impedance mismatch between input and output, the circuit may be susceptible to feedback current leakage, so it may be necessary to provide the following form of protection: PCB protection ring. Although not classified as a protected area, the protection ring does act as a physical barrier to external components and wiring, and prevents internal current from leaving the area. Nu er vi klar til at se på, hvordan vi sikrer, at reservationer gør deres job.

Stay away from trouble

PCB retention measures are only effective if they actually achieve their objectives. This is to provide isolation in specific areas of the board from any and all external elements. To achieve this, you need to follow these good Keepout guidelines.

PCB retention criterion

L Bestem, hvorfor tilbageholdelse er påkrævet

L Determine how much space is needed according to usage

L Use screen printing markers to identify reservation areas

L Ensure that your design document contains retention information

PCB hold is a valuable asset to your board design, ensuring that it performs as expected. Ved at følge disse retningslinjer og drage fuld fordel af dem, kan du undgå layoutkonflikter og forbedre PCBA -pålideligheden efter implementering.