Material Selection
Chemitalic A/S, Revision 3. July 2005
Most of a circuit board cost price derives from laminate and prepregs, regarding which, the choice is determined by electrical, thermal, mechanical and environmental properties. This section describes Chemitalic's standard range of laminates, prepregs and copper foil for multilayer build-ups. Choosing materials within these standard types, the lowest cost price and the shortest delivery time can be achieved.
1: Material properties
Table 1 shows typical parameters for printed circuit boards built up using Chemitalic's standard laminates and prepregs.
The FR4 and BT epoxy types are UL approved; RCC foil and halogen-free laminates are in the process of being approved, please contact our sales department for information about the UL approval status of these types.
Table 1: Material properties, typical
| Laminate type Parameter |
FR4 standard |
FR4 halogen- free |
FR4 Hi Tg |
RCC foil |
BT epoxy |
Arlon 25FR |
Rogers 4350B |
| Tg°C |
140 (DSC) |
150 (DSC) |
170 (DSC) |
175 (DMA) |
200 (DSC) |
- |
280 (TMA) |
| CTE Z (preTg) ppm/*K |
50 |
60 |
50 |
60 |
55 |
59 |
50 |
| CTE X (preTg) ppm/*K |
15 |
12 |
15 |
60 |
14 |
16 |
16 |
| Dk |
4.0 – 4.6 (1MHz) |
4.6 – 4.9 (1MHz) |
4.0 – 4.6 (1MHz) |
3.6 (1MHz) |
3.9 – 4.2 (1MHz) |
3.58 (10GHz) |
3.48 (10GHz) |
| Df |
0.015 (1MHz) |
0.020 (1MHz) |
0.015 (1MHz) |
0.020 (1MHz) |
0.008-0.010 (1MHz) |
0.0035 (1MHz) |
0.004 (1MHz) |
| High operating temp. power components |
X |
X |
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| Special components and assembly techniques |
X |
X |
X |
||||
| Multiple layers High complexity |
X |
X |
X |
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| High frequency |
X |
X |
X | ||||
| Green products |
X |
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| Standard products |
X |
X |
Multilayer circuit boards are built up using FR4 or BT epoxy laminates as core material and prepregs as bonding material between the laminates. Copper foil forms the outer layers. In the following we have listed Chemitalic's standard range of laminates, prepregs and copper foils. All laminates and prepregs permit multilayer build-ups with a UL 94V0 flammability classification.
2: FR4 Laminates, RCC foil and prepregs.
Laminates and pregpregs listed in table 2 are tetra functional FR4 laminates/prepregs from Polyclad, type PCL-FR-226. (GE 313). Glass transition temperature Tg is 140°C by DSC, maximum continuous operating temperature for multilayer boards constructed from these laminates and prepregs is 105°C.
The RCC Foil Polyclad PCL-CF-400 is a two pass epoxy-resin coated foil with Tg = 170°C (DMA), it is fully compatible with FR4 laminates and prepregs.
Table 2: Standard FR4 laminates, RCC foil and prepregs
For list with higher frequences, please contact GPV
Type |
Cu Foil 1 (micron) |
Cu Foil 2 (micron) |
Core Thickness (mm) |
Dielectric Constant |
|
FR4 Laminate |
18 |
18 |
0.1 |
4.3 |
|
FR4 Laminate |
35 |
35 |
0.1 |
4.3 |
|
FR4 Laminate |
18 |
18 |
0.15 |
4.1 |
|
FR4 Laminate |
35 |
35 |
0.15 |
4.1 |
|
FR4 Laminate |