What is Copper Clad Laminate?
Copper Clad Laminate, abbreviated to CCL, is a type of basic product of PCBs. With glass fiber or solid wood pulp paper as reinforcing product, a CCL is a type of product through lamination with copper clad on each one side or both sides of reinforcing product after getting soaked in resin.
How are CCLs Classified?
According to various classification requirements, CCLs can be classified into different categories:
• Based on CCL mechanised rigidity, we've inflexible CCL (FR-4, CEM-1, etc.) and flex CCL. Inflexible PCBs be determined by inflexible CCLs while flex PCBs are on flex CCLs (flex-rigid PCBs are on both inflexible CCLs and flex CCLs).
• Based on insulation product and set ups, we have natural resin CCL (FR-4, CEM-3, etc.), metal-base CCL, ceramic-base CCL etc.
• Based on CCL thickness, we've standard width CCL and thin CCL. The previous one requires at least 0.5mm width while the latter can be thinner than 0.5mm. Copper foil width can be excluded from CCL width.
• Based on reinforcing material forms, we have glass fiber cloth basic CCL (FR-4, FR-5), paper basic CCL (XPC), ingredient CCL (CEM-1, CEM-3).
• Based on used insulation resin, we've epoxy resin CCL (FR-4, CEM-3) and Phenolic CCL (FR-1, XPC).
CCLs only succeed when catering to performance specifications in the following aspects:
• Appearance. Issues could be induced on copper foil because of unexpected components in manufacturing method such as dent, damage, resin level, wrinkle, pinhole, bubble etc. All those issues will certainly lead to reduced functionality of CCL and then PCB. Therefore, a fantastic CCL should be flat and smooth in appearance.
• Size. Since CCLs are base product of printed circuit boards, they have to conform to size requirements related to PCBs. Guidelines concerning the size of CCLs contain length, width, diagonal deviation and warpage, each of which includes to meet particular requirement.
• Electric performance. This is an essential mission to get a PCB so any element affecting its electric performance has to be carefully developed including dielectric constant (Dk), dielectric damage tangent (Df), quantity resistance, surface level of resistance, insulation resistance, arc level of resistance, dielectric break down voltage, electric power, Comparative Tracking Index (CTI) etc.
• Physical performance. Guidelines concerning physical efficiency of a CCL contain dimensional stability, peel off strength (PS), bending durability, heat resistance (integrating thermal anxiety, Td, T260, T288, T300), punching high quality etc.
• Chemical performance. Chemical performance of the CCL has to meet the specifications of flammability, chemical reagents amount of resistance, Tg, Z-axis coefficient of thermal growth (Z-CTE), dimensional stability etc.
• Environmental efficiency. It has to cater to the requirements with regards to water absorption etc.
CCL quality judgement should be completed by PCB Fab Houses. Take PCBCart for example, it can be applied IPC-4101C as a manufacturing regular and makes use of IPC-TM-650 for CCL testing. Accordingly, such methods lead CCLs to get certified substrate of PCBs.
Prepreg, the reinforcing product inside a CCL, is made from glass fiber after being baked. Additionally it is known as bonding sheet by some people and constructed by epoxy resin, glass fiber cloth, DMF, 2MI, acetone etc.
What is Copper Foil?
In accordance with performance, copper foil can be classified into regular copper foil that is applied for FR-4 and paper platform board, HTE that is applied for multi-layer PCBs to feed back split ring issue and low user profile (LP) copper foil that is requested multi-layer PCBs as well.
What is New Pattern of CCL?
In order to cater to the regulations of RoHS (Restriction of Hazardous Substances), higher specifications are brought on CCLs in terms of temperature resistance and stability. Modifications are implemented from the following two aspects:
• Halogen-free CCL. It identifies to CCLs whose information of chlorine (Cl) and bromine (Br) is managed within 900ppm while their general content is no more than 1500ppm. Performance assessment between halogen-free CCLs and regular FR-4 CCLs is summarized into the following table.
• Lead-free CCL. It identifies to CCLs whose area mounting is completed without the application of lead-free solder. The primary resin of lead-free CCLs is brominated epoxy resin. Based on the polices of RoHS, six elements such as PBB and PBDE are no more found in CCLs. Compared with DICY curing system (with dicyandiamide as curing agent) applied in ordinary FR-4 CCLs, lead-free CCLs take advantage of PN curing system (with Phenol-formaldehyde resin as curing agent).
Because of one decade's attempts and experience, PCBCart has been enjoying a dynamic function in adding to the flourishing of this business. Certified by ISO 9001, UL and RoHS, it is completely capable of offering high-quality and environmental-friendly PCBs with related kind of CCLs at economical costs.
Comments
Post a Comment