ENGINEERING TECHNOLOGY
RESEARCH CENTER
What is a Surface Finish?
A surface finish may be defined as a “coating” located at the outermost layer of a PCB
(which is dissolved into the solder paste upon reflow or wave soldering) (which is dissolved into the solder paste upon reflow or wave soldering)
Two Main Types of Coatings Finish Surface
• Metallic
• Organic
Note:
(Base) Metal Plating is typically copper (in most cases).
But, in a few (like ENIG) the Nickel-phosphorous(5-12% P co-deposit) serves as the solderable surface.
Why use a Surface Finish?
The surface finish protects the PCB
Surface Copper until it’s Assembled
How to Select a Proper Surface Finish?
Reasons for Finishes Reasons for Finishes
• Coplanarity (See Below)
• Lead-Free (RoHS and WEEE) (RoHS 5 or RoHS 6)
• Contact Resistance (Compression Connection)
• Tarnish Resistance
• Press-fit Requirements
• Wear Resistance
• Hardness
• Chemical Resistance Chemical Resistance
• Wire Bonding (Au or Al?)
• Cost
• Compatibility with other Surface Finish
surface_finish_new_2011.pdf
| Process | Description | Tolerance | Figures(mm) | |
| A.Lamination | 1.Multi-layer alignment precision | ±3mil | ||
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| 2.Minimum laminated board thickness | 0.4MM | |||
| 3.Board thickness tolerance | <1.0以下±0.1MM，1.0以上±10% | |||
| B.Basic Material | 1.Material | FR-4,铝基，高频板材，聚四氟已烯，厚铜箔，纸板，BT板材，PI板材，Rogers4003,pp4403, | ||
| 2.Thickness capability | 最小0.2MM,最大6.0 | |||
| 3.Thickness capability(HAL) | 最小0.6MM,最大3.0mm | |||
| C.Drilling | 1.Maximun drill size | 6.5mm | ||
| 2.Minmum drill size | 0.2mm | |||
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| 3.Hole size tolerance | ±3mil | |||
| 4.true position tolerance | ±3mil | |||
| 5.Slot true position tolerance | 孔径〈10MM以下：公差±0.2MM，孔径≥10以上：公差±0.2MM | |||
| 6.Slot width tolerance | 孔径〈10MM以下：公差±0.2MM，孔径≥10以上：公差±0.2MM | |||
| 7.Slot length tolerance | 孔径〈10MM以下：公差±0.2MM，孔径≥10以上：公差±0.2MM | |||
| 8.Slot length to width ratio | 2:01 | |||
| 9.Aspect Ratio | ||||
TECHNICAL CAPBILITY
surface_finish_new_2011.pdf
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