Buried and Blind Via technique in HDI Flex-rigid PCBs
Combining the supporting function
contributed by rigid boards and the functions of high density and
flexibility contributed by flex boards, rigid-flex boards enjoy the
irreplaceable advantages of lightness, thinness and small size of
electronic products. To meet these advantages, the designers mainly
adopt the blind/buried via and High Density Interconnecting (HDI)
techniques. This blog is going to state some blind/buried via technique
in HDI rigid-flex PCBs.
Above all, we have to take a closer look for the dedicated material for the HDI rigid-flex PCBs. We usually use the FR4 copper foil for the rigid parts and the specific PI for the flexible part. Because of the easy occurrence of delamination of rigid-flex boards, acrylic acid adhesive should be picked up as pre-preg of rigid-flex associative part , in order to meet the viscidity requirement. Silicone rubber as lamination material and PET release film as mold cleaner are used during the lamination processes. All these materials should be paid much attention before going to fabrication.
Then for the via technique. We should focus on three main processes.
The first one is lamination. There are two types of lamination methods: one-step lamination and step-by-step lamination. One-step lamination means laminating all the inner layers for one time, with the advantages of saving time and cost. But it's difficult to position the cover player. Once the lamination defect, the problem can only be found in the process of etching. On the contrary, step-by-step lamination means laminates respectively flexible layer and rigid layer. In this way, it can easily position the cover layer and graph offset in inner layer. Once there is any problem, it can be found immediately. But this method has the disadvantages of time consumption and cost increasing with the corresponding material needed.
The second process is the drilling technique. There are two types of drilling we usually used for the blind and buried vias. One is NC drilling and the other is laser drilling. And nowadays, we also can adopt the UV drilling for the blind vias. But UV drilling is a new high-tech which is quite complicated, it requires extract cost for the fabrication.
The last technique is the plasma cleaning technique. Plasma cleaning is the removal of contaminants on the via wall through the use of an energetic plasma together with acrylic acid. Gases such as argon and oxygen as well as mixtures such as air and hydrogen/nitrogen are used. This is a complicated physical-chemical reaction. After this process, the HDI rigid-flex PCB can run much better.
In a word, there are techniques we need to know about buried/blind via in HDI flex-rigid PCBs. Hope this blog can help you know more about HDI rigid-flex PCBs, our website:www.fastturnpcbs.com
Above all, we have to take a closer look for the dedicated material for the HDI rigid-flex PCBs. We usually use the FR4 copper foil for the rigid parts and the specific PI for the flexible part. Because of the easy occurrence of delamination of rigid-flex boards, acrylic acid adhesive should be picked up as pre-preg of rigid-flex associative part , in order to meet the viscidity requirement. Silicone rubber as lamination material and PET release film as mold cleaner are used during the lamination processes. All these materials should be paid much attention before going to fabrication.
Then for the via technique. We should focus on three main processes.
The first one is lamination. There are two types of lamination methods: one-step lamination and step-by-step lamination. One-step lamination means laminating all the inner layers for one time, with the advantages of saving time and cost. But it's difficult to position the cover player. Once the lamination defect, the problem can only be found in the process of etching. On the contrary, step-by-step lamination means laminates respectively flexible layer and rigid layer. In this way, it can easily position the cover layer and graph offset in inner layer. Once there is any problem, it can be found immediately. But this method has the disadvantages of time consumption and cost increasing with the corresponding material needed.
The second process is the drilling technique. There are two types of drilling we usually used for the blind and buried vias. One is NC drilling and the other is laser drilling. And nowadays, we also can adopt the UV drilling for the blind vias. But UV drilling is a new high-tech which is quite complicated, it requires extract cost for the fabrication.
The last technique is the plasma cleaning technique. Plasma cleaning is the removal of contaminants on the via wall through the use of an energetic plasma together with acrylic acid. Gases such as argon and oxygen as well as mixtures such as air and hydrogen/nitrogen are used. This is a complicated physical-chemical reaction. After this process, the HDI rigid-flex PCB can run much better.
In a word, there are techniques we need to know about buried/blind via in HDI flex-rigid PCBs. Hope this blog can help you know more about HDI rigid-flex PCBs, our website:www.fastturnpcbs.com
评论
发表评论