PCB Technical - Single-sided circuit board and UL94V-0 on circuit board

Single-sided circuit board introduction

Single-sided circuit board (single-layer PCB board) contains only one layer of conductive material, which is suitable for low-density design. Since the late 1950s, single-sided PCB boards have existed and still dominate the global market in absolute numbers. Single-sided printed circuit boards are easy to design and fast to manufacture. They are the most cost-effective platforms in the industry. Like Led Lighting products, most LED PCBs use one layer of PCB, FR4 or aluminum.

Commonly used materials for single-sided circuit boards

94HB, 94VO, FR4, CEM1, CEM-3, copper substrate, aluminum substrate, etc.

Single-sided circuit board application range

A large number of single panels are used in power supplies, relays (automotive and industrial), timing circuits, sensor products, LED lighting, radio and stereo equipment, packaging equipment, monitoring, calculators, printers, coffee manufacturers, vending machines, solid state drives, Camera systems and other industries.

Features of single-sided circuit boards
Single board is on the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side. Because the wires only appear on one side, we call this kind of PCB a single-sided. Because single-sided boards have many strict restrictions on the design of the circuit (because there is only one side, the wiring cannot cross and must be around a separate path), only early circuits use this type of board.

Single-panel wiring diagrams are mainly screen printing, that is, a resist is printed on the copper surface, and after etching, the mark is printed with a solder mask, and finally the part guide hole and the part are completed by punching. shape. In addition, some products that are produced in small quantities and diversified use photoresist to form patterns.
Introduction of circuit board UL94V-0

Flammability UL94 rating is the most widely used material flammability performance standard. It is used to evaluate the ability of a material to extinguish after being ignited. According to the burning speed, burning time, anti-drip ability and whether the drops are burning, there are many ways to judge.

Each tested material can get many values according to color or thickness. When the material of a certain product is selected, its UL rating should meet the thickness requirements of the wall part of the plastic part. The UL rating should be reported together with the thickness value. It is not enough to report only the UL rating without the thickness.

The flame retardant grades of plastics increase gradually from HB, V-2, V-1 to V-0:

HB: The lowest flame retardant grade in the UL94 standard. It is required that for samples with a thickness of 3 to 13 mm, the burning rate is less than 40 mm per minute; for samples with a thickness of less than 3 mm, the burning rate is less than 70 mm per minute; or extinguished before the 100 mm mark.

V-2: After two 10-second burning tests are performed on the sample, the flame goes out within 60 seconds. There may be burning materials falling.

V-1: After the sample is subjected to two 10-second burning tests, the flame is extinguished within 60 seconds. No burning objects should fall.

V-0: After the sample is subjected to two 10-second burning tests, the flame is extinguished within 30 seconds. No burning objects should fall.

Method of testing UL94V-0
1. The material is classified as UL94HB horizontal combustion measurement method.

2, the material is classified as UL94V-0 ULV-1 ULV-2 vertical burning test method.

3. The material is classified as UL-5V vertical burning test method.

4. The material is classified as 94VT M-0, 94VT M-1, 94VT M-2 vertical burning test method.