Cymcap Hot Crack

If "Cymcap Hot Crack" refers to a feature within a software or a manufacturing process related to Cymcap, it could potentially be about:

In cracked regions, EDS identified Mn-rich intermetallic phases (CuMn₃Ni) and trace P segregation at grain boundaries. These low-melting-point constituents solidify last and serve as crack propagation paths under tension.

Based on the above, the following were tested: cymcap hot crack

| Strategy | Modification | Result | |----------|--------------|--------| | Reduce Mn | 12% → 9% | Freezing range 190°C → 150°C; no cracks | | Add grain refiner | 0.05% Zr | Finer equiaxed grains; crack length reduced 70% | | Reduce cooling rate | 5°C/s → 1°C/s from 950°C | Eliminated cracks in original composition | | Eliminate P | <0.005% | Reduced intergranular embrittlement |

Cymcap alloy was obtained from failed commercial capacitors (Group A) and from virgin cast ingots (Group B). Chemical composition verified by inductively coupled plasma optical emission spectroscopy (ICP-OES) is shown in Table 1. If "Cymcap Hot Crack" refers to a feature

Table 1: Composition of Cymcap alloy (wt%)

| Element | Cu | Mn | Ni | Fe | Si | P | |---------|----|----|----|----|----|----| | Nominal | Bal.| 12.0 | 3.0 | 0.5 | 0.1 | <0.02 | | Measured| 84.2| 11.8 | 3.1 | 0.5 | 0.12| 0.015| Given the 890°C solidus, “Cymcap hot crack” is

Welder technique matters. A cold crater (abrupt stop) creates a solidification void. As the weld cools, the surface tension pulls the crater apart, initiating a crack that runs back into the cap.

The sequence is as follows:

Given the 890°C solidus, “Cymcap hot crack” is a misnomer if referring to reflow (260°C). More likely, the cracks form during capacitor manufacturing when Cymcap is applied as a slurry and fired at 900–1000°C (thick-film process). During that high-temperature firing, the alloy partially melts, and solidification shrinkage creates hot cracks. Later, reflow soldering exposes and propagates these pre-existing cracks.

Thus, Cymcap hot crack = solidification crack from thick-film firing.