SAC405 solder alloy (Sn95.5/Ag4.0/Cu0.5): when more silver is needed
The 4 % silver alloy for joints subjected to severe thermal cycling
SAC405 (Sn95.5/Ag4/Cu0.5) is a lead-free alloy with more silver than SAC305. It is chosen when the specification requires it or when joints must withstand intense thermal cycling. The extra silver does not improve resistance to shock and drop, where low-silver alloys perform better. It costs more than SAC305: for most applications SAC305 is sufficient. Ideal for automotive and critical applications. Discover also SAC305.
Why Choose SAC 405
When choosing more silver makes sense
SAC 405 Technical Specifications
Characteristics of the Sn95.5/Ag4/Cu0.5 alloy
| Property | Value | Unit | Notes |
|---|---|---|---|
| Composition | Sn95.5/Ag4/Cu0.5 | % | 4 % silver, 0.5 % copper |
| Melting range | 217–219 | °C | Solidus–liquidus |
| Standards | IPC J-STD-006 | - | Alloy designation |
| Compliance | RoHS, REACH | - | Lead-free alloy |
SAC405 or SAC305?
SAC405 and SAC305 have the same copper and almost the same melting range: only the silver changes, 4 % versus 3 %. The extra silver increases the fraction of Ag3Sn compounds in the joint and therefore its mechanical strength, but also the cost of the alloy. With slow cooling, such a high silver content can form large Ag3Sn platelets, which reduce fatigue life: the cooling profile must be controlled.
| Situation | Recommended alloy |
|---|---|
| The customer's specification requires SAC405 | SAC405 |
| Joints exposed to severe thermal cycling | SAC405 or SAC305, depending on validation |
| Industrial and consumer electronics | SAC305 |
| High-volume wave and selective soldering | SAC0307 or 99SnCuNiGe |
Availability
SAC405 is not a stock alloy: we supply it on request, in the format and quantity required. For stock alternatives see the overview of lead-free alloys and the alloys for automotive electronics.
SAC 405 Applications
Sectors that require maximum reliability
Automotive electronics
Control units and modules exposed to severe thermal cycling, when the specification requires SAC405.
Power electronics
Inverters, converters and power supplies with joints stressed by on/off cycles.
Industrial electronics
Controls and instrumentation for environments with high temperatures and thermal cycling.
Lighting and power LEDs
Modules subject to cyclic heating during operation.
SAC 405 vs SAC 305: Technical Comparison
When to choose SAC 405 instead of SAC 305
| Characteristic | SAC405 (4 % Ag) | SAC305 (3 % Ag) | Note |
|---|---|---|---|
| Composition | Sn95.5/Ag4/Cu0.5 | Sn96.5/Ag3/Cu0.5 | The only difference is the silver |
| Melting range | 217–219 °C | 217–220 °C | Comparable process profiles |
| Mechanical strength | Higher | High | More Ag3Sn compounds in the joint |
| Cost | Higher | Medium | Depends on the silver price |
| Typical use | High-reliability specifications | The electronics standard | SAC305 is enough in most cases |
SAC405 is chosen when the specification requires it or when joints are exposed to severe thermal cycling; for general electronics SAC305 is the standard, and SAC0307 reduces cost in bath processes.
Frequently Asked Questions about SAC 405
Everything you need to know about the high-reliability alloy
Request Advice on SAC 405
We help you work out whether your application really needs SAC405 or whether SAC305 is enough
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