Tom
12-18-2001, 09:30 AM
Here is a quote from Tyco San Diego division (Specialty Materials Group) regarding the use of Rogers 5880 for "High Speed" boards......
Rogers 5880 material is not a multilayer friendly material, it is designed for microstrip and stripline applications. The material has tremendous unpredictable material shrinkage, it can shrink from .001 to .004 per inch.
This causes two issues: warpage when mixed with other materials which have a different CTE in X-Y and the design would have to have very generous pad to hole sizes to allow for the material movement. On paper 5880 looks great, it has the lowest loss tangent and very low dielectric constant. To achieve these values electrically the material sacrifices mechanical aspects like low CTE in X-Y and Z axis'.
Dale
(Dale is the product engineering manager at Tyco San Diego)
Rogers 5880 material is not a multilayer friendly material, it is designed for microstrip and stripline applications. The material has tremendous unpredictable material shrinkage, it can shrink from .001 to .004 per inch.
This causes two issues: warpage when mixed with other materials which have a different CTE in X-Y and the design would have to have very generous pad to hole sizes to allow for the material movement. On paper 5880 looks great, it has the lowest loss tangent and very low dielectric constant. To achieve these values electrically the material sacrifices mechanical aspects like low CTE in X-Y and Z axis'.
Dale
(Dale is the product engineering manager at Tyco San Diego)