Tom
10-11-2002, 08:48 PM
IPC Advanced Study Guide Page Reference: Page 121, Section 2.7
It is important for the designer to understand the relationship of core material and prepreg.
Although this is really identified on the master drawing, it does impact the performance of the final product. Being somewhat vague in the construction characteristics on the master drawing permits the manufacturer to give you the optimum cost for their particular manufacturing process and the type of laminate that they feel most comfortable in using.
Nevertheless, it should be recognized that when one switches from one manufacturer to another, one may also be switching to a new construction and may also be using another supplier's material. Thus, the more detailed the documentation requirements, the more the repeatability of the fabrication and board performance. However, one should be prepared that not every board manufacturer will be able to meet the same requirements as documented by the user.
Mixing and matching of material will continue. Rigid-flex boards use polyimide film and rigid sections of FR4 reinforced laminate. These are glued together with special adhesive in order to make certain that the products are laminated into a homogenous construction. They can also be intermixed with metal cores in order to provide the coefficient of thermal expansion requirements necessary, thus understanding combinations of reinforcement, resin systems, and mixing and matching these properties helps meet the end-product requirements.
When material is purchased by the board manufacturer according to any one of the specification sheets listed in IPC-4101, the material is provided with a certificate of compliance (CFC). Suppliers of laminate and prepreg have assessed their manufacturing capability according to the standard. The IPC has also developed a Laminator's Qualification Profile. The document is identified as IPC-1730. This gives a detailed qualification assessment of the laminator listing all of the characteristics that have been tested for the various type laminates being produced.
It is important for the designer to understand the relationship of core material and prepreg.
Although this is really identified on the master drawing, it does impact the performance of the final product. Being somewhat vague in the construction characteristics on the master drawing permits the manufacturer to give you the optimum cost for their particular manufacturing process and the type of laminate that they feel most comfortable in using.
Nevertheless, it should be recognized that when one switches from one manufacturer to another, one may also be switching to a new construction and may also be using another supplier's material. Thus, the more detailed the documentation requirements, the more the repeatability of the fabrication and board performance. However, one should be prepared that not every board manufacturer will be able to meet the same requirements as documented by the user.
Mixing and matching of material will continue. Rigid-flex boards use polyimide film and rigid sections of FR4 reinforced laminate. These are glued together with special adhesive in order to make certain that the products are laminated into a homogenous construction. They can also be intermixed with metal cores in order to provide the coefficient of thermal expansion requirements necessary, thus understanding combinations of reinforcement, resin systems, and mixing and matching these properties helps meet the end-product requirements.
When material is purchased by the board manufacturer according to any one of the specification sheets listed in IPC-4101, the material is provided with a certificate of compliance (CFC). Suppliers of laminate and prepreg have assessed their manufacturing capability according to the standard. The IPC has also developed a Laminator's Qualification Profile. The document is identified as IPC-1730. This gives a detailed qualification assessment of the laminator listing all of the characteristics that have been tested for the various type laminates being produced.