J-STD-033 Bake Conditions

IPC/JEDEC J-STD-033 Bake Conditions

Different packages have different levels of moisture sensitivity. The higher the amount of moisture inside a package, the higher the thermomechanical stresses inside the package during board mounting will be. These stresses are brought about by the rapid vaporization of the trapped moisture, and can be large enough to fracture the package during board mounting. Package cracking under such circumstances is known as 'popcorn cracking.' IPC/JEDEC J-STD-020 defines the Moisture Sensitivity Levels (MSL) of surface mount devices.

Moisture-sensitive devices are baked and vacuum-sealed inside a moisture barrier bag prior to shipment in order to minimize their tendency to exhibit popcorn cracking during board mounting. Users of such devices are likewise required to board mount the units within a prescribed period after the bag has been opened. Failure to do so calls for a rebake of the units prior to board mounting.

Table 1 shows the bake conditions recommended by IPC/JEDEC J-STD-033 at the user's site if the out-of-bag time prescribed has expired prior to board mounting. Table 2 shows the bake conditions required by IPC/JEDEC J-STD-033 at the manufacturer's site, prior to dry-packing the parts.

Table 1. IPC/JEDEC J-STD-033 Bake Conditions

for Drying SMD's at the User Site

Pkg Thickness	MSL	Bake @ 125C		Bake @ 90C/<=5%RH		Bake @ 40C/<=5%RH
Pkg Thickness	MSL	Saturated @ 30C/85%	@ Floor Life Limit + 72H @ 30C/60%	Saturated @ 30C/85%	@ Floor Life Limit + 72H @ 30C/60%	Saturated @ 30C/85%	@ Floor Life Limit + 72 H @ 30C/60%
<= 1.4 mm	2a	5 H	3 H	17 H	11 H	8 D	5 D
	3	9 H	7 H	33 H	23 H	13 D	9 D
	4	11 H	7 H	37 H	23 H	15 D	9 D
	5	12 H	7 H	41 H	24 H	17 D	10 D
	5a	16 H	10 H	54 H	24 H	22 D	10 D
<= 2.0 mm	2a	21 H	16 H	3 D	2 D	29 D	22 D
	3	27 H	17 H	4 D	2 D	37 D	23 D
	4	34 H	20 H	5 D	3 D	47 D	28 D
	5	40 H	25 H	6 D	4 D	57 D	35 D
	5a	48 H	40 H	8 D	6 D	79 D	56 D
<=4.5 mm	2a	48 H	48 H	10 D	7 D	79 D	67 D
	3	48 H	48 H	10 D	8 D	79 D	67 D
	4	48 H	48 H	10 D	10 D	79 D	67 D
	5	48 H	48 H	10 D	10 D	79 D	67 D
	5a	48 H	48 H	10 D	10 D	79 D	67 D

Table 2. IPC/JEDEC J-STD-033 Bake Conditions Prior

to Dry Packing SMD's at the Manufacturer's Site

Pkg Thickness

MSL

Bake @ 125C

Bake @ 150C

<= 1.4 mm

8 Hours

16 Hours

21 Hours

24 Hours

28 Hours

4 Hours

8 Hours

10 Hours

12 Hours

14 Hours

<= 2.0 mm

23 Hours

43 Hours

48 Hours

11 Hours

21 Hours

24 Hours

<= 4.5 mm

48 Hours

24 Hours

Reliability Engineering; Solder Heat Resistance Test (SHRT)

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