TO-252, also known as DPAK, is a semiconductor package developed for surface mounting on circuit boards. It represents a surface-mount variant of TO-251 package, and smaller variant of the D2PAK package, also known as TO-263. DPAK is suitable for medium-power applications (reference values 80W*/60A), while D2PAK is for higher power application (reference values 100A).
A common Bill Of Materials would include a Ni plated copper leadframe, Pb solder die attach, Al wire for the intereconnects and a molding compound to keep it all together.

A great solution for the molding compound can be GR 600. Hysol GR600 Series is a black semiconductor-grade epoxy molding compound designed for the encapsulation and protection of power discrete semiconductor packages, such as DPAK, D2PAK, TO220 and TO251 packages. It has achieved commercial success with many uses on TO applications.

EMC Chemistry	GR600SL2	GR600A	GR600	GR600P1
Platform	TO252/251/263	TO252/251/263	TO252/251/263	TO252/251/263
Resin Type	EOCN + LWA-3	LWA-1 + LWA-2	LWA-1	MAR + Flexible
Hardener Type	PN + LWA-1	LWA-m	LWA-m	--
Filler Loading	85±1%	88±1%	88±1%	88±1%
Filler Type	Spherical + Angular	Spherical	Spherical	-
Catalyst	P/N	P/N	P/N	-
MSL Performance	MSL3  (Cu/Ag plating)	MSL3  (Cu/Ag plating)	MSL1  (Cu/Ag plating)	MSL1  (Cu/Ag plating)

 

Property / Product	Unit of Measure	GR600 SL2	GR600 A	GR600	GR600 P1
UNCURED PROPERTIES
Hot Plate Gel time,  @ 175°C	s	25	41	28	38
Spiral Flow @ 175°C	in	32	53	32	25
Flammability		1/8’’ V-0	1/8’’ V-0	1/8’’ V-0	1/8’’ V-0	UL94 V-0
Halogen-free (Green)		✔	✔	✔	✔	Green product
TYPICAL CURED PROPERTIES
Specific Gravity, g/cc	g/cc	2.03	1.97	2.00	2.11
Glass Transition Temperature, TMA	°C	153	113	122	124
Coefficient of Thermal Expansion (CTE)     Alpha1     Alpha2	ppm/C ppm/C	10 43	9.8 28	6.8 26	14 36	Low CTE
Viscosity, @175°C	Pa.s	TBD	14	25	29
Flexural Strength, @25°C	MPa	138	139	139	142
Flexural Modulus, @25°C	GPa	19.1	19.8	17.6	19.8	Low stress
Storage Modulus (DMA), @25°C	Gpa	26.1	24.7	27.0	25.8
Storage Modulus (DMA), @175°C	Mpa	2798	736	1273	1312
Storage Modulus (DMA), @260°C	MPa	923	599	897	863
Shore-D Hardness @ 90s, 175°C	-	84	75	83	80
Moisture Absorption, 24hr PCT	%	0.25	0.25	0.18	0.22	Low water absorption

TO-220 is a "power package" intended for power semiconductors and an example of a through-hole design rather than a surface-mount technology type of package. TO-220 packages can be mounted to a heat sink to dissipate several watts of waste heat. 

TO-257 is a hermetically sealed metal package that is otherwise considered equivalent to TO-220.

Silicone Carbide TO packages

TIMS are not the only product category that has to be "custom made" for Power modules. High power requires not just dissipation but also thermally stable semiconductor materials that can withstand the rigourous thermal cycling requirements. These range from die attach, encapsulants and bonding wires to epoxy molding compounds.

Epoxy molding compounds such as the GR750 series and GR15F-MOD2C are made with power modules in mind. With exquisite thermal performance these compounds have a very high Glass transition temperature and easy pass HTRB tests while keeping high MSL levels. They are designed for high power devices with low moisture absorption requirements.

Epoxy Molding compounds for TO through hole devices

Epoxy Molding Compounds for TO Surface mount devices

Hysol High Thermal Conductivity EMC for Power Modules and TO Packages