PCB Technical - Produce PCB Meeting Halogen-Free Requirements

1, Preface

With the increasing demand for environmental protection in the world, people pay more and more attention to the halogen problem. According to the requirements of iec61249-2-21, the maximum content of halogen in the electronic welding materials, resins and the information for enhancing the performance of halogen-free PCB is determined, Halogen free has become another green revolution of electronic profession since the implementation of RoHS Directive on July 1, 2006.

2, What does halogen mean

Electronic waste containing bromine and chlorinated compounds and plastic products contain halogen flame retardants and PVC. When these products are discarded and burned, they are prone to produce harmful substances dioxin and acid gas (HCl), which will damage the environment and human health through bioaccumulation. The United Nations World Environmental program has listed them as persistent organic pollutants. Halides are widely used in PCB, solder masks, molding compounds, connectors, and other common electronic products. For example, there are halogen-containing materials in flame retardants of PCB, among which the toxicity of PBB and PBDE is the most concerned. Many by-products, including dioxins and furan like compounds, as well as acidic or corrosive gases, occur in PCB and electronic products containing halogen under incomplete combustion, which have potential damage to the environment and human health. Most power and communication cables now contain halogens, which emit toxic aerosols when burned. In case of fire, the acid gas generated by cable burning will damage people's nose, mouth and throat, and the smoke is also easy to make people lose their way and difficult to escape from the fire scene. Therefore, EU ROHS regulations prohibit the use of PBB and PBDE in PCB. Now some people try to restrict the use of all halogen-containing materials in electronic devices. They believe that when burning electronic devices, bromination data will generate highly toxic dioxins. They asked to stop the use of halogenated data beyond RoHS's rule of restricting only PBB and PBDE. Halogen free may become another green revolution in the electronic profession since the implementation of RoHS (restriction on hazardous substances) directive on July 1, 2006. Compared with the damage caused by halides, the damage caused by six harmful substances (Pb, CD, Hg, Cr6 + and PBDE, PBB) restricted by ROHS directive is more shocking. In the meantime, lead will directly damage the nervous system; Cadmium can damage bone, kidney and respiratory system; Mercury can damage the central nervous system and kidney system; Hexavalent chromium will cause genetic defects; PBDE and PBBs are highly carcinogenic and teratogenic substances. From lead-free, ROHS to halogen-free, to the POHS directive in Norway, which requires the prohibition of the use of 18 kinds of harmful substances, the increasingly stringent environmental requirements for information can not only significantly reduce the environmental pollution caused by electronic products, but also effectively protect our health.

Market driving factors for halogen elimination:

(1) Environmental and health concerns

(2) Some brominated flame retardants are indeed toxic (polybrominated biphenyls, polybrominated diphenyl ethers)

(3) Many brominated flame retardants are structurally similar to known toxic PCB s

(4) It stimulates the prevention of all brominated flame retardants

(5) Toxic and by-products caused by termination of product life and combustion treatment

(6) Dioxin formation by incomplete combustion of halogen

(7) Room temperature combustion of discarded electrical appliances is prevalent all over the world

(8) Environmental arrangements for brominated flame retardants

(9) Driven by environmental arrangements, OEMs are seeking halogen-free solutions and extending this requirement to the entire supply chain.

(10) Major OEM announcements to eliminate bromide

Apple: elimination of PVC and BFRs at the end of 2008

Dell: eliminating brominated flame retardants in 2009

HP: elimination of PVC and BFRs in 2009

A small number of dioxins and furans are formed during combustion of chlorinated carbohydrates. According to the fire data, the level of furan and dioxin has little effect on human health.

PCB

4, Halogen free regulations and their contents

According to various industrial specifications, the acceptable halogen content is 900 ppm for bromine, 900 ppm for chlorine, and the maximum total halogen content is 1500 ppm.

IPC low halogen electronic specification working group 4-33a & JEDEC jc14 Committee: it is necessary for all PCB substrates to meet the requirements of low halogen bromine and chlorine defined in ipc-4101b specification. Now RoHS II is being revised. With regard to halogen from many different sources, as well as the minimum limit effect of low level halogen content on the environment, most institutions adopt the content level regulated by the international Electrochemical Commission (IEC) as the requirement for their final installed products.

5, Detection and analysis of non halogenation

In order to prove that the materials used for PCB do not contain halogen, it is necessary for the manufacturer to carry out combustion test, and then determine whether there are halogen elements by ion chromatography. The data of brominated activators are decomposed during combustion. In these data, the atoms in the bromide are covalently bonded to form bromide molecules at room temperature.

(1)prEN 14582 Characterication of waste – Halogen and sulfur content – Oxygen combustion in closed systems and determination method

method A (Calorimetric bomb method)

method B (Schoniger flask combustion method)

(2) IEC 61189-2 test method is used for electronic data, PCB board, interconnection structure and assembly parts. Application of Part 2 test 2C12 test method to interconnected structural components

(3)JPCA-ES-01-2003

(4)IPC TM-650 (Number2.3.41)

6, Challenges and opportunities for halogen free process

Halogenation free movement for our Chinese enterprises, as long as we meet the challenge, there is no chance, because we are forced to abide by the rules.

We must learn from the lead-free, halogen-free series of environmental protection campaign, to arouse our vigilance. We managed to deal with lead-free, and soon halogen-free came into being. If we deal with PCB the past without halogenation, there will soon be a new movement that we don't expect. Because the essence of the movement is "containment", and there are various means to achieve this intention. For the sake of demand, we can always find a reason to make a fuss. The reason why Europe and the United States dare to do so is to see the weakness of "R & D vacancy" commonly existing in Chinese enterprises, beat you, but let you have no strength to fight back, either knocked down or forced to block.