Why do components require low humidity storage?

Low humidity storage of sensitive Surface Mount Devices as specified by IPC/JEDEC J-STD-033B.1 (January 2007) "Standard for Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices."

McDry Prevents Micro-Cracking of IC Packages During Reflow.

Micro Cracks Micro-cracking occurs in nearly 100% of IC packages containing moisture during the Reflow process. This results in the corrosion of printed circuits for an extended period of time causing breakage of wiring and other problems. Micro-cracking can be prevented with storage and dehumidification of IC’s using McDry.

Some IC Packages are only guaranteed for 24 hours after they have been removed from moisture barrier bags (MBBS). Outside of the MBB, IC packages absorb moisture from the atmosphere which can result in micro-cracking during the Reflow process. To prevent micro-cracking, moisture containing IC’s can be baked or stored in McDry ultra-low humidity storage cabinets.

With respect to the above-mentioned floor life and dry box management, the management standard has been specified in IPC-JEDEC-J-STD-033B.1 McDRY conforms to the standard.

McDry Storage Diagram

What are the requirements for component storage?

Absorption and Dehumidification
Some IC Packages are only guaranteed for 24 hours after they have been removed from moisture barrier bags (MBBS). Outside of the MBB's, IC packages absorb moisture from the atmosphere which can result in micro-cracking during the Reflow process. To prevent micro-cracking, moisture containing IC's can be baked or stored in McDry ultra-low humidity storage cabinets.

What is the correct way to store components?
LOW HUMIDITY STORAGE OF COMPONENTS

Option 1: Moisture Barrier Bags

Process:
Moisture-sensitive components must be placed in a moisture barrier bag with a desiccant and RH indicator. The moisture barrier bag is then sealed.

Costs:
Moisture barrier bag - Desiccant - RH indicator - Sealing Machine - Manual Labor

Option 2: Nitrogen Cabinet

Process:
Moisture-sensitive components are placed in Nitrogen Cabinets for low humidity storage.

Costs:
Cabinet - Nitrogen - Construction work to run N2 lines to the cabinet

Option 3: Mcdry Low Humidity Storage Cabinets

Process:
Moisture-sensitive components are placed in Mcdry Cabinets for low humidity storage.

Costs:
Cabinet - Electricity

Technical Benefits

McDry Cabinets are able to absorb moisture from components to help prevent defects such as micro-cracking.

Cost Benefits of McDry Cabinets

Compared to Option 1

  • Eliminates the need to purchase moisture barrier bags, desiccants and RH indicators.
  • Eliminates the need for manual labor.

Compared to Option 2

  • Eliminates the cost of nitrogen.
  • Eliminates the need for nitrogen lines.

McDry Cabinets can eliminate the need for baking of some components.

Recommendations for IC Package Storage after Opening Moisture-Barrier Bags — As specified by IPC/JEDEC Standard 033B.1

  Storage Method Workability and Cost Result
1 Use before floor life ends
  • The floor life differs according to each IC package. Once an MBB has been opened, it is difficult to use leftover components for the next mounting process before the floor life ends.
Insufficient
2 Storage in dry box
  • When IC packages are stored in a dry box at 5%RH or lower, the floor life is indefinite permitting storage and use of a quantity of components as needed. Just-in-time mounting is possible.
  • Unlike repacking and baking, management of man-hours is unnecessary and substantial reduction in costs is possible.
  • The floor life can be reset in a dry box(10%RH or under). (MS Level 2-3: Resetting possible when the exposure time is within 12 hours.)
  • The floor life can be reset in a dry box(5%RH or under). (MS Level 4-5,5a: Resetting possible when the exposure time is within 8 hours.)
  • It is possible to store tape reels that are vulnerable to heat and cannot be baked.
  • IC packages can be placed in a dry box temporarily when trouble occurs during mounting operation.
Optimal storage and easy operation
3 Repacking
  • There is a time limit to repacking. For example, NEC Electronics has set 168 hours as the allowable time after repacking for storage of MSDs.
  • It takes time to check moisture-barrier bags for damage and holes as well as to replace desiccants with fresh ones.
  • Only 60 minutes are available to reseal after moisture-barrier bags are opened so quick operation is necessary.
  • Resealing performance may not be completely reliable.
Time consuming
4 Baking
  • IC packages that have exceeded their floor life must be baked in time for mounting which is a troublesome process.
  • Baking oxidizes pins deteriorating wettability of solder.
  • It is a requirement to put baked IC packages on a heat-resistant tray and displacement or pin bending may result.
  • Tape reels cannot be baked.
Process heavy

Level and Floor Life of IC packages

IPC/JEDEC J-STD-033B.1 (Joint Electron Device Engineering Council) The floor life of IC packages after removal from moisture-barrier bags is classified into the levels shown below.

Level Floor life (Moisture absorption life when IC packages are left in factory conditions at
1 No specific floor life in factory conditions
2 1 year
2a 4 weeks
3 168 hours
4 72 hours
5 48 hours
5a 24 hours
6 Baking is required.

Label on Moisture-Barrier Bags

It is compulsory to indicate the level, floor life and storage temperature after unpacking on the moisture-barrier bags.

Label on Moisture Bag

Dry Box Storage Guideline as Recommended by IPC/JEDEC J-STD 033B.1

(Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Mount Devices.)

According to IPC/JEDEC J-STD 033B.1, IC packages should be stored in a dry box capable of maintaining either 10%RH or 5%RH in order to prevent components from absorbing moisture.

Storage in a cabinet below 5%RH: No limit in floor life.
Storage in a cabinet below 10%RH: Please see chart below for examples.

(Section of Table 7-1 from IPC/JEDEC J-STD 033B.1)

Package
Type and
Body
Thickness
Moisture
Sensitivity
Level
Floor life depending on humidity and temperature Temp
5* 10* 20* 30* 40* 50* 60* 70* 80* 90*
Body
Thickness
> 3.1mm
including
PQFPs
>84 pins,
PLCCs
(square)
All
MQFPs
or
All BGAs
> 1mm
2a











94

124

167

231
44

60

78

103
32

41

53

69
26

33

42

57
16

28

36

47
7

10

14

19
5

7

10

13
4

6

8

10
←35ºC
←30ºC
←25ºC
←20ºC
3











8

10

13

17
7

9

11

14
6

8

10

13
6

7

9

12
6

7

9

12
4

5

7

10
3

4

6

8
3

4

5

7
←35ºC

←30ºC

←25ºC

←20ºC
4





3

5

6

8
3

4

5

7
3

4

5

7
2

4

5

7
2

3

5

7
2

3

4

6
2

3

3

5
1

2

3

4
1

2

3

4
←35ºC

←30ºC

←25ºC

←20ºC
5





2

4

5

7
2

3

5

7
2

3

4

6
2

2

4

5
1

2

3

5
1

2

3

4
1

2

2

3
1

1

2

3
1

1

2

3
←35ºC
←30ºC
←25ºC
←20ºC
5a





1

2

3

5
1

1

2

4
1

1

2

3
1

1

2

3
1

1

2

3
1

1

2

2
1

1

1

2
1

1

1

2
1

1

1

2
←35ºC
←30ºC
←25ºC
←20ºC

* %RH

Resetting of Floor Life for MSLs 2~3 in a Dry Box Following IPC/JEDEC J-STD-033B.1(Example of Room Temperature Dehumidification.)

According to IPC/JEDEC J-STD-033B.1, IC packages for moisture-sensitivity levels 2-3 that have been removed from MBBs must be kept in dry storage capable of maintaining no greater than 10% RH. The floor life of these components can be reset if stored in a dry box at 10%RH for five times the exposure period(under the conditions of 30 degrees C, 60% RH.) The exposure time is limited to a maximum of 12 hours.

IC Package Dehumidification

Resetting of Floor Life for MSLs 4~5, 5a in a Dry Box.

IC packages with moisture-sensitivity levels of 4~5,5a should be stored in a dry box capable of maintaining no greater than 5%RH. The floor life of the components can be reset by storing the packages within a dry cabinet capable of maintaining 5%RH or lower for a period of ten times the exposure period (under conditions of 30 degree C, 60% RH). The exposure time is limited to a maximum of 8 hours.

Manufactured for High Performance

McDry Functions

Dehumidifying Principle

Dehumidifying Principle

McDry(TM) Electronic Drying Storage Cases provide low humidity storage without the use of nitrogen. Humidity is removed from the cabinets by use of a powerful zeolite desiccant. The desiccant is automatically recycled with a heating mechanism thus optimizing its absorption capability and does not require replacement. Moisture absorbed by the powerful zeolite desiccant is vaporized and released outside of the cabinet. Memory shaped metal is utilized for fail proof ventilation. Natural air-flow convection system desiccates the entire cabinet without requiring the use of a fan.

Test Data of Humidity Levels Within McDry Cabinets

ESD electrostatic discharge

DXU-1001 (1%RH)
DXU-1001 Test Data
MC-1001(3%RH)
MC-1001 Test Data
(Ambient test conditions: 25, 60%RH)
Elapsed time (hr)

DXU-1001(1% RH)

Change in humidity inside the dry box after power is turned off (Assumption of service interruption)

MCU-401 (3%RH)
MCU-401 Test Data MCU-401 Test Data
(Ambient test conditions: 25, 60%RH)
Elapsed time (hr)

Data on Door Opening/Closing

MCU-401 (3%RH)

MCU-401 Data on Door Opening

Location and time of door opening/closing
No.(1)…2 doors(A)(B)…Simultaneoues opening for 2 min.
Nos. (2)(3)(4)(6)…1 door(A)…Opening for 20 sec.
No.(6)…1 door(A)…Opening for 1 min.
No.(7)…1 door(A)…Opening for 30 sec.

DXU-1001 (1%RH)

DXU-1001 Data on Door Opening

DXU-1001 Location and time of door opening/closing
No.(1)…4 doors(A)(B)(C)(D)…Simultaneoues opening for 2 min.
Nos. (2)(5)(7)(9)(10)(11)(12)…1 door(A)…Opening for 20 sec.
Nos.(3)(8)…1 door(A)…Opening for 30 sec.
No.(4)…2 doors(A)(B)…Simultaneous opening for 30 sec.
No.(6)…2 doors(A)(B)…Simultaneous opening for 2 min.
No.(13)…2 doors(A)(B)…Simultaneous opening for 1 min.

Electrostatic Discharge of McDRY: ESD Control

The electrostatic discharge of McDRY conforms to IEC61340-5-1.
McDry Resistance Formula
McDRY Electrostatic Discharge

Between Shelves

McDRY Electrostatic Discharge

Shelf ← → Door

McDRY Electrostatic Discharge

Shelf ← → Ground

McDRY Electrostatic Discharge

Door ← → Ground

McDRY Electrostatic Discharge

Data on moisture absorption and dehumidification of an IC package

IC Package Moisture Absorption and Dehumidification Data
Pretreatment: 24-hour baking at +125°C Measurement condition
  1. Component stored in ambient environment(30 degrees C, 85%RH) for 25 hours.
  2. Dehumidification: The component is stored in a McDry cabinet at 5%RH for 150 hours.
  3. The component was baked and then stored in McDry at 5%RH. (Example of storage in a dry box at 5% RH specified by the new IPC/JEDEC J-STD-033B.1)

Example of low-humidity storage of laminated PCB

Multi-layered PCBs absorb moisture at a faster rate as they become thinner. Layer break off and blistering will occur during reflow if the moisture content of the PCB exceeds 0.2% (weight.) Store laminated PCBs in an ultra-low humidity dry box.

PCB (Glass-epoxy substrate)

Example of low-humidity storage of laminated PCB

Sample: 6-layered laminated PCB
Dimensions: 50 x 100 x 1t (mm)
Measurement condition
Pretreatment: Baked for 24 hours at 125?
Humidification: Steamed for 2 hours
Dehumidification: Stored in McDry box at 5% RH

PBGA carrier board

PBGA carrier board PBGA

Test Conditions
Pretreatment: 24-hour bake at +125

  1. Component stored in ambient environment(30 degrees C, 85%RH) for 25 hours.
  2. After process (1), the component is stored in McDry cabinet(5%RH) for 150 hours.
  3. Stored in McDry cabinet(5% RH) after baking.

Handling and Storage of IC Packages

Storing in 5 % RH and 10 % RH storage cabinets in accordance with IPC/JEDEC J-STD 033B.1

In accordance with IPC/JEDEC J-STD-033B.1, IC packages that have been removed from MBBs must be kept under a condition 5% or 10% relative humidity to prevent components from absorbing moisture. However, during the mounting process, opening and closing of dry cabinet storage doors may occur frequently in order to remove and replace moisture-sensitive devices. This will allow ambient air to flow into the cabinet and may raise the RH level. To limit this from occurring and to keep the relative humidity inside of the cabinet below 5% or 10% as specified, a consistent, ultra-low humidity storage level is recommended. Therefore, the storage guidelines utilizing the McDry cabinet corresponding to the repetition of opening and closing of doors are as follows:

Model RH level Frequency of opening and closing of doors Usage example
DXU models 1% RH Once in approx.
20 — 40mins.
  1. Ultra-low humidity storage of ICs for cabinets that are accessed frequently.
  2. Storage of IC packages that require ultra-low humidity storage such as components with high MSL classifications.
MCU models 3% RH Once in approx.
1hr — 2hrs.
  1. Ultra-low humidity storage of ICs for cabinets that are not accessed frequently.
  2. Long-term storage of IC packages and electrical components.
  3. Storage of PCBs, etc.

Storage of IC packages Within McDry

IC Package Taping Using McDry

Taping Using McDry

Examples of McDry Applications (Items that require low-humidity storage)

1 Low-humidity storage of IC packages (MSD) which have been removed from moisture barrier bags. (To sHOME the floor life clock of CSPs, BGAs, TQFPs, etc.)
  1. Low-humidity storage of MSDs before and leftover after implementation.
  2. Low-humidity storage of MSDs that hve been removed from mounter.
  3. Low-humidity storage of MSDs when writing ROMs.
McDry
2 Dry storage of semi-mounted PCBs. Effective low-humidity storage of PCBs awaiting second-side reflow. McDry
3 Drying and storing multilayer PC boards before and after the mounting process. McDry
4 Dry storage of pattern film and prepreg used in the manufacturing of PCBs. McDry
5 Clean, room temperature drying of liquid crystal glass boards after washing. Results in even drying and prevents contamination. McDry
6 Dry storage of quartz crystals and electrode adhesives used in the manufacturing of quartz oscillators. McDry
7 Dehumidification and low-humidity storage of optical fiber (micro-lens for WDM) and CCD (charge-coupled device) McDry
8 Slows down oxidation and prevents corrosion of electronic components and provides low-humidity storage of polymeric materials. McDry

Example of use of McDRY in mounting process (Products that need low-humidity storage)

McDry Mounting Process

Hygrometer with alarm

Hygrometer with alarm

A visual and audible alarm is triggered when the humidity exceeds the set parameters.

Data logger

Data logger

Humidity data is recorded at all times.

Sliding shelf

Sliding shelf

The shelf slides in order that items can be removed easily.

N2 socket

N2 socket

Nitrogen purge is available

Reel rack

Reel rack

A variety of tap reels can be stored efficiently.

ESD Caster Wheels

ESD Caster Wheels

ESD safe casters can be sold for the MCU type as an option. (The casters are provided for the DXU type as standard equipment.)

Shelves

Shelves

Additional shelves can be purchased for all models.

Adjustor

Adjustor

Adjusts the height of the unit. Adjustors are inserted into anchor holes that also function to keep the unit from moving. (Modification for some models required.)

Tower Light

Tower Light

The tower light flashes when humidity goes over the level set using the hygrometer with alarm.

Wrist strap

Wrist strap

Promptly diffuses static electricity away from the cabinet.

ERC-301B Hygrometer

ERC-301B Recommended for ISO-9000

The digital hygrometer ERC-301B is used to monitor humidity levels within McDRY.

Specifications

  • Static capacitance type sensor
  • Measuring range: 1-50% RH
  • Accuracy: ±3% RH
  • 4 AA Alkali batteries; approx. 1-year service life

Features:

Batteries are utilized so that in the event of power supply interruption or when the cabinet is unplugged for relocation, the meter may continue to display the humidity level within the cabinet. Contact us when a calibration certificate is necessary.

IC packages should be stored in a dry box (McDRY) at Be sure to calibrate the hygrometer at least once a year.

ERC-301AD Hygrometer with Alarm

By setting the RH limit with the ERC-301AD hygrometer, an alarm light will flash when the humidity level becomes too high.

  1. The alarm light will flash when the humidity level goes over the set limit after a fixed period of time.
  2. After the alarm light flashes, the unit will save 10 data readings, one per hour
  3. When the humidity level goes over the set limit, the (optional) light tower will flash and a buzzer will sound.
ERC-301AD

Specifications

  1. Humidity settings: 5 RH 10 RH 20 RH
  2. Time settings: 60 min. 120 min. 180 min.
  3. Excess humidity: Alarm light flashes
  4. Humidity data after the alarm 10 data
    readings (1 per hour)
  5. Power: 4 AA Alkali batteries; approx.
    1-year service life

Example: Humidity data after the alarm light flashes (1 reading per hour)

Time (h) Humidity RH
0 30
1 30
2 30
3 40
4 40
5 40
6 40
7 40
8 40
9 40

DXU-1002-L 2% RH (Deep Style)
DXU-4006 2% RH
DXU-1004-800
Light Tower and Audible Alarm

DXU-1002-L 2% RH (Deep Style)

Storage cabinet for tape feeder with reel

In the text box of Tape Feeder, change to: Tape reels can be stored attached to the feeder and placed in the cabinet.

DXU-1002-LDXU-1002-L Drawing

Item/type DXU-1002-L
External Dimensions 47.2Wx37.4Dx72.8H(in)
Internal Dimensions 45.3Wx35.4Dx62.0H(in)
Capacity Approx 56 Cu Feet (1600 Liters)
Dry Unit US-5000x2
Material Higt-grade steel construction with ESD-safe and Anti corosion coating
Color Silver
Doors (Magnetic) 4 Doors with glass windows
Weight Approx 550 lbs., 250kgs
Electrical Requirement AC 120V(50/60Hz)94w/h(Max 740w)
Accessories Included Casters, RH, Meter, 5 Shelves

In addition to the type shown above, deeper cabinets are also available. Contact us for details

DXU-4006 2% RH

Feeder wagon and magazine rack storage cabinet

DXU-4006DXU-4006 Drawing

Door opening/closing data (The two doors are kept opened for 5 and 10 minutes.)

DXU-4006 Test Data

Item/type DXU-4006
External Dimensions 65.0Wx52.0Dx86.8H(in)
Internal Dimensions 58.6Wx43.3Dx84.0H(in)
Capacity Approx 134 Cu Feet (3800 Liters)
Dry Unit US-5000x8
Material Higt-grade steel construction with ESD-safe and Anti corosion coating
Color Ivory
Doors (Magnetic) 2 Doors with glass windows
Weight Approx 2,200 lbs., 1,000 kgs.
Electrical Requirement AC 120V(50/60Hz)380w/h(Max 500w)
Accessories Included Casters, RH Meter, 1 Shelf

DXU-1004-800

Large storage cabinet

DXU-1004-800DXU-1004-800 Test Data

Item/type DXU-1004-800
External Dimensions 79.0W x33.3Dx72.8H(in)
Internal Dimensions 74.8Wx31.0Dx62.0H(in)
Capacity Approx 84 Cu Feet (2400 Liters)
Dry Unit US-5000x2
Material Higt-grade steel construction with ESD-safe and Anti corosion coating
Color Silver
Doors (Magnetic) 4 Doors with glass windows
Weight Approx 1,000 lbs. (450kgs.)
Electrical Requirement AC 120V(50/60Hz)94w/h(Max 740w)
Accessories Included Casters,RH Meter,1 shelves

In addition to the type shown above, deeper types are also available. Contact us for details.

Light Tower and Audible Alarm

Hygrometer with alarm

Light Tower and Audible Alarm