English
Views: 4 Author: Site Editor Publish Time: 2026-08-18 Origin: Site
Strong die cast heat sink performance starts on the drawing board. This guide covers ADC12 vs A380, wall thickness, draft, porosity control, and the DFM rules that keep cooling effective while the part stays easy and cheap to cast.
A die cast aluminum heat sink looks simple, but the design choices you make before the die is cut decide whether it cools well, ships cheaply, and scales cleanly. Alloy, wall thickness, draft, and porosity control are the four levers that matter most.
This guide walks through each one with DFM rules you can hand to a supplier. If you have not read the overview yet, start with our die cast heat sink guide; for application examples, see the servo, LED, and automotive article. To source a part, our custom die casting heat sink manufacturer page covers prototyping to mass production.
Both are silicon-rich cast aluminums with good fluidity and low hot-cracking risk.
10. ADC12 — flows slightly better, fills thin sections easily, common and economical in Asia.
11. A380 — a bit stronger and tougher, common in North America.
Conductivity of both is around 80-90 W/mK — lower than pure aluminum but fine for most air-cooled sinks. Pick by cost, availability, and the strength your mount needs. If you are weighing conductive metals more broadly, our copper vs aluminum heat sink guide helps.
Zinc die casting flows even better and holds tighter tolerances, but it is heavier and conducts worse for the mass. Use it only for small, weight-tolerant, precision parts — not for most heat sinks.
Keep walls as uniform as you can. Sudden thick-to-thin changes cause shrink sinks and localized porosity. A practical minimum wall for aluminum die casting is about 1.0-1.5 mm; thinner than that risks short fills and cold laps.
Design rule: set one target wall and let fins, base, and features share it. Uniform walls fill evenly and cool evenly, which protects both yield and conductivity. For the comparison with processes that allow thinner fins, see die casting vs cold forging.
Die-cast fins need a draft taper (typically 1-3 degrees per side) so the part slides out of the die without sticking or scrapping. That taper makes die-cast fins thicker than extruded or skived fins — an accepted trade for the shape freedom you gain.
Design rule: build the draft into the 3D model from day one. Adding it later means re-cutting the die. If you need near-vertical fins, talk to your supplier about slide cores or a different process.
Porosity — tiny air pockets trapped as the metal freezes — is the main thermal risk in die casting. It lowers local conductivity and can be a leak path if the part later carries fluid.
12. Gate and vent well — fill from the thick end toward the fins so air escapes.
13. Keep hot spots away from the heat path — place risers and vents where cooling matters least.
14. Use vacuum assist or squeeze pins — these cut gas porosity where conductivity is critical.
15. Avoid isolated thick sections — they are where shrinkage porosity hides.
For the most thermal-critical or fluid-carrying parts, consider cold forging (fully dense) instead — see the die casting vs cold forging comparison.
16. Base flatness — the mounting face should be flat so contact resistance to the chip stays low; plan any light machining.
17. Fixings in the die — threads, inserts, and clips cast in beat adding them later.
18. Finish — anodizing adds corrosion resistance and a clean look; confirm the spec (and any salt-spray need) early. See the anodized aluminum heatsink guide.
Item | Decision to lock |
Alloy | ADC12 / A380 / zinc |
Wall | Uniform, min ~1.0-1.5 mm |
Draft | 1-3 deg per side on fins and walls |
Porosity | Gate, vent, vacuum assist where needed |
Fixings | Inserts, threads, clips in the die |
Finish | Anodize spec, flatness tolerance |
Test | Thermal check or salt-spray if required |
For a custom run, our custom aluminum heat sink manufacturer page takes this checklist from drawing to mass production.
A die cast aluminum heat sink lives or dies by the choices made before tooling. Pick the alloy by flow and strength, keep walls uniform, design the draft in from the start, and control porosity where the heat flows. Do those four things and you get a one-piece, low-cost, high-volume sink that cools reliably. Skip them and you will fight scrap and hot spots after the die is cut.
If you have a drawing, send it over and we will return a DFM review and thermal check — free, no obligation.
Call to Action (CTA) Have a die cast aluminum heat sink drawing? Send it over and we will return a DFM review covering alloy, wall, draft, and porosity — plus a thermal check — within 24 hours, free. |
Q1: What is the minimum wall thickness for a die cast aluminum sink?
About 1.0-1.5 mm for aluminum. Thinner risks short fills and cold laps; if you need thinner fins, extrusion or skived fin may fit better.
Q2: How much draft do die-cast fins need?
Typically 1-3 degrees per side. Build it into the model early; adding it after the die is cut means rework.
Q3: Can porosity be designed out?
Largely yes — good gating, venting, vacuum assist, and keeping hot spots off the heat path keep it low. For near-zero porosity, cold forging is the alternative.
Q4: ADC12 or A380 — which should I choose?
Both conduct similarly; ADC12 flows better and is common in Asia, A380 is a bit stronger and common in North America. Pick by cost and mount strength.
Q5: Can die cast sinks be anodized?
Yes, anodizing is standard for corrosion resistance and appearance; confirm the spec before the die is cut.
Q6: Should fixings be cast in or added later?
Cast them in. Inserts, threads, and clips in the die beat adding them later in cost and reliability.
