Electro-Brite E-Prep Desmear/Etchback

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E-Prep 100 Series Permanganate
E-Prep 200 Series Permanganate
Electro-Brite E-Prep Solvent II
E-Prep Hole Cleaner 320
E-Prep Hole Cleaner 340
Electro-Brite E-Prep Neutralizer
Electro-Brite E-Prep Glass Etch II
 

E-Prep 100 Series Permanganate

Product Description
The E-Prep 100 Series Permanganate process is a potassium permanganate system designed to efficiently desmear or etchback printed circuit hole walls, while providing superior topography for increased adhesion of direct metallization or electroless copper.
The E-Prep system is capable of desmear/etchback on a wide variety of laminate materials, including difunctional, tetrafunctional, multifunctional, polyimide, and non-MDA polyimide. It has been designed to provide etchback, limiting the effects of material variation.
The use of Electrochemicals' EPR regeneration system allows for continuous regeneration of the manganate back into useable permanganate. This ensures steady state operation and a consistently high level of useable permanganate in the E-Prep 100 bath. This results in consistent desmear or etchback. Solution life is greatly extended with this system and lab analysis frequency can be greatly reduced. This results in high reliability and low maintenance.

The E-Prep process consists of three steps:
  • Preconditioning with E-Prep Solvent II or E-Prep Hole Cleaner
  • Desmearing with E-Prep 100 Series Permanganate
  • Neutralizing with E-Prep Neutralizer
Solution makup
E-Prep 101 80 g/L
E-Prep 102 5.3 % by volume
Deionized Water Balance
Operating conditions
  Nominal Range
E-Prep 101 80 g/L 60 - 90 g/L
E-Prep 102 5.3% by vol(40 g/L NaOH) 5 - 8% by vol (38 - 61 g/L NaOH)
Temperature 79°C(175°F) 68 - 85°C (155 - 185°F)
Time 10 min. 5 - 20 min.


During bath operation the total manganate breakdown product must be maintained below 30 g/L.
Recommended process cycle
  1. E-Prep Hole Cleaner or E-Prep Solvent II
  2. Double Cascade Rinse
  3. E-Prep 100 Series Permanganate
  4. Dead Rinse
  5. Double Cascade Rinse
  6. E-Prep Neutralizer
  7. Rinse
  8. *E-Prep Glass Etch (optional as a separate step, or combined with the Neutralizer)
  9. Rinse
  10. *10% v/v sulfuric acid for crust removal (optional if required glass etch parameters form significant amount of crust)
* optional steps
Important considerations
For lower Tg FR4 laminate and other materials highly sensitive to permanganate attack the following guidelines should be followed:

Process Chemistry Concentration Temperature Dwell Time
Hole Swell E-Prep Solvent II 50% 60 - 71°C (140 - 160°F) 1 - 4 min.
Permanganate E-Prep 101 60 - 75 g/L 68 - 74°C (155° - 165°F) 5 - 12 min.
  E-Prep 102 5 - 6%    
Neutralizer E-Prep Neutralizer 10 - 20% 43 - 49°C (110 - 120°F) 4 - 6 min.
  H2SO4 6 - 8%    
Glass Etch E-Prep Glass Etch II 4 - 12 g/L (light) 50 - 70 g/L (heavy)   2 - 5 min.


For higher Tg materials or laminates less susceptible to permanganate attack the following guidelines should be followed:

Process Chemistry Concentration Temperature Dwell Time
Hole Swell E-Prep Solvent II 50 - 100% 71 - 82°C (160 - 180°F) 2 - 10 min.
Permanganate E-Prep 101 75 - 93 g/L 74 - 85°C (165° - 185°F) 5 - 12 min.
  E-Prep 102 5 - 6%    
Neutralizer E-Prep Neutralizer 10 - 20% 43 - 49°C (110 - 120°F) 4 - 6 min.
  H2SO4 6 - 8%    
Glass Etch E-Prep Glass Etch II 4 - 12 g/L (light) 50 - 70 g/L (heavy)   2 - 5 min.

For high Tg resins a double pass may be required to obtain sufficient removal.
For heavy glass etch the use of a 10% sulfuric acid solution is recommended as a crust remover.
Bath operation and maintenance
Guidelines for EPR regeneration of permanganate are included towards the end of this data sheet. An E-Prep Troubleshooting Guide is also included.

The E-Prep 101, E-Prep 102 and manganate content of the oxidizer bath are maintained by wet analysis as outlined in this data sheet. A UV / VIS spectrophotometer analysis method for the E-Prep 101 and manganate is also included.

The following weight loss test should be performed on a regular basis on all the different laminate types in use. The weight loss results will vary greatly across different laminate types, and may vary across different lot numbers of the same laminate. Weight loss data should be compared with topography and smear removal analysis to maintain optimum control of the process. The optimum weight loss range for a given laminate type should be determined from several factors including, but not limited to:
  • Desmear or etchback amount required.
  • Lamination Process operating latitude.
  • Down stream processes such as electroless copper or direct metallization operating windows.

Your Electrochemicals sales representative should be consulted when new laminate types or suppliers are used.

Laminate Weight Loss Test
  1. Strip the copper off of the laminate to be tested. (no drilled holes)
  2. Cut the bare laminate into accurately measured 3" x 3" (8 cm x 8 cm) coupons, and scribe a label.
  3. Bake the coupon(s) for 15 minutes at 120°C (248°F).
  4. Cool and weigh accurately to four decimal places.
  5. Process through the desmear/etchback cycle to be evaluated.
  6. Dry the coupon(s) and bake for 2 hours at 120°C (248°F).
  7. Cool and reweigh the coupon(s)
  8. Calculation:
Weight loss(mg/cm2) = [Initial Weight (mg) - Final Weight (mg)] / surface area(cm2)
Note:
A 3" x 3" coupon equals 116.1288 cm2.
An 8 cm x 8 cm coupon equals 128 cm2.

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E-Prep 200 Series Permanganate

Product Description
The E-Prep 200 Series Permanganate Process is a concentrated sodium permanganate system designed to etchback or desmear printed circuit hole walls, and promote increased topography for superior adhesion of the subsequent electroless copper or direct metallization.

The E-Prep system is capable of desmear/etchback on a wide variety of laminate materials, including difunctional, tetrafunctional, multifunctional, polyimide, and non-MDA polyimide. It has been designed to provide etchback, limiting the effects of material variation.

The use of Electrochemicals' EPR regeneration system allows for continuous regeneration of the manganate back into useable permanganate ensuring steady state operation and a consistent level of desmear or etchback. Solution life is greatly extended with this system and lab analysis frequency can be greatly reduced resulting in high reliability and low maintenance.

The E-Prep process consists of three steps:
  • Preconditioning with E-Prep Solvent II or E-Prep Hole Cleaner 320
  • Desmearing with E-Prep 200 Series Permanganate
  • Neutralizing with E-Prep Neutralizer
Solution makup
Deionized Water 81.7% by volume
E-Prep Liquid Oxidizer 201 13% by volume
E-Prep Liquid Oxidizer 102 5.3% by volume
Operating conditions
  Nominal Range
E-Prep 201 13% 10 - 25%
E-Prep 102 5.3% by vol (40 g/L NaOH) 5 - 8% by vol (38 - 61 g/L NaOH)
Temperature 79°C(175°F) 68 - 85°C (155 - 185°F)
Time 10 min. 5 - 20 min.
Agitation Thorough Mechanical
Tanks Titanium, Stainless Steel, molded Polyethylene or Polypropylene
Heaters Titanium, Stainless Steel or Teflon


During bath operation the total manganate breakdown product must be maintained below 25 g/L.
(*Nominal conditions are recommended for desmear of standard FR4 material. Testing is required for optimization of specific laminate types and conditions.)
Recommended process cycle
  1. 1. E-Prep Solvent II or E-Prep Hole Cleaner 320
  2. Double Cascade Rinse
  3. 3. E-Prep 200 Series Permanganate
  4. Dead Rinse
  5. Double Cascade Rinse
  6. E-Prep Neutralizer
  7. Rinse
  8. *E-Prep Glass Etch (optional as a separate step, or combined with the Neutralizer)
  9. Rinse
  10. *10% v/v sulfuric acid for crust removal (optional if required glass etch parameters form significant amount of crust)
* optional steps
Important considerations
For lower Tg FR4 laminate and other materials highly sensitive to permanganate attack the following guidelines should be followed:

Process Chemistry Concentration Temperature Dwell Time
Hole Swell E-Prep Solvent II 50% 60 - 71°C (140 - 160°F) 1 - 4 min.
Permanganate E-Prep 201 10 - 15% 68 - 74°C (155° - 165°F) 5 - 12 min.
  E-Prep 102 5 - 6%    
Neutralizer E-Prep Neutralizer 10 - 20% 43 - 49°C(110 - 120°F) 4 - 6 min.
  H2SO4 6 - 8%    
Glass Etch E-Prep Glass Etch II 4 - 12 g/L (light) 50 - 70 g/L (heavy)   2 - 5 min.


For higher Tg materials or laminates less susceptible to permanganate attack the following guidelines should be followed:

Process Chemistry Concentration Temperature Dwell Time
Hole Swell E-Prep Solvent II 50 - 100% 71 - 82°C (160 - 180°F) 2 - 10 min.
Permanganate E-Prep 201 20 - 25% 74 - 85°C (165° - 185°F) 5 - 12 min.
  E-Prep 102 5 - 6%    
Neutralizer E-Prep Neutralizer 10 - 20% 43 - 49°C (110 - 120°F) 4 - 6 min.
  H2SO4 6 - 8%    
Glass Etch E-Prep Glass Etch II 4 - 12 g/L (light) 50 - 70 g/L (heavy)   2 - 5 min.

For high Tg resins a double pass may be required to obtain sufficient removal.
For heavy glass etch the use of a 10% sulfuric acid solution is recommended as a crust remover.
Bath operation and maintenance
Guidelines for EPR regeneration of permanganate are included towards the end of this data sheet. An E-Prep Troubleshooting Guide is also included.

The E-Prep 201, E-Prep 102 and manganate content of the permanganate bath are maintained by wet analysis as outlined in this data sheet. A UV/VIS spectrophotometer analysis method for E-Prep 201 and manganate is also included.

The following weight loss test should be performed on a regular basis on all the different laminate types in use. The weight loss results will vary greatly across different laminate types, and may vary across different lot numbers of the same laminate. Weight loss data should be compared with topography and smear removal analysis to maintain optimum control of the process. The optimum weight loss range for a given laminate type should be determined from several factors including, but not limited to:
  • Desmear or etchback amount required.
  • Lamination Process operating latitude.
  • Down stream processes such as electroless copper or direct metallization operating windows.

Your Electrochemicals sales representative should be consulted when new laminate types or suppliers are used.

Laminate Weight Loss Test
  1. Strip the copper off of the laminate to be tested. (no drilled holes)
  2. Cut the bare laminate into accurately measured 3" x 3" (8 cm x 8 cm) coupons, and scribe a label.
  3. Bake the coupon(s) for 15 minutes at 120°C (248°F).
  4. Cool and weigh accurately to four decimal places.
  5. Process through the desmear/etchback cycle to be evaluated.
  6. Dry the coupon(s) and bake for 2 hours at 120°C (248°F).
  7. Cool and reweigh the coupon(s)
  8. Calculation:
Weight loss(mg/cm2) = [Initial Weight (mg) - Final Weight (mg)] / surface area(cm2)
Note:
A 3" x 3" coupon equals 116.1288 cm2.
An 8 cm x 8 cm coupon equals 128 cm2.

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Electro-Brite E-Prep Solvent II

Product Description
Electro-Brite E-Prep Solvent II is a biodegradable hole sweller used to condition the hole wall prior to desmear and/or etchback treatment with E-Prep 100 or 200 series permanganate solutions.

This initial step enhances the smear removal abilities of the permanganate system. The result is a clean, microporous hole wall, which is an ideal surface for subsequent electroless copper or direct metallization processes.
Solution makup
E-Prep Solvent II 50% by volume
Deionized Water Balance


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E-Prep Hole Cleaner 320

Product Description
E-Prep Hole Cleaner 320 is an alkaline cleaning solution designed to condition the hole wall prior to desmear and/or etchback treatment with E-Prep 100 or 200 series permanganate solutions.

This initial step enhances the smear removal abilities of the permanganate system. The result is a clean, microporous hole wall, which is an ideal surface for subsequent electroless copper or direct metallization processes.
Solution makup
  Deionized Water 75.5% by volume
  E-Prep Hole Cleaner 320 20% by volume
  E-Prep 102 4.5% by volume

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E-Prep Hole Cleaner 340

Product Description
E-Prep Hole Cleaner 340 is a biodegradable solvent based conditioning solution used to prepare resinous substrates for treatment in alkaline permanganate solutions.

When used in conjunction with the E-Prep Series Permanganate, Hole Cleaner 340 uniformly penetrates resin smear for effective desmear and etchback. This product is equally effective on FR-4, FR-5, tetra-functional, poly functional, and polyimide resin systems and is replenishable for longer solution life. Boards need not be dried prior to processing .

Hole Cleaner 340 has very low surface tension for excellent wetability in small holes.
Solution makup
E-Prep Hole Cleaner 340 50 - 100% by volume
Deionized Water Balance

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Electro-Brite E-Prep Neutralizer

Product Description
E-Prep Neutralizer is a sulfate system that neutralizes the permanganate residue left on the hole wall after the E-Prep Permanganate step. E-Prep neutralization is of great importance because permanganate residue can contaminate or reduce the effectiveness of following steps in the electroless or direct metalization processes.

If your E-Prep process is set up for desmear and you wish to frost the glass fibers to improve topography, E-Prep Glass Etch II can be added directly to the Neutralizer bath.
Solution makup
Deionized Water Balance
Sulfuric Acid 7% by volume
E-Prep Neutralizer 15% by volume
Glass Etch II (optional) 9 g/L

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Electro-Brite E-Prep Glass Etch II

Product Description
E-Prep Glass Etch II can be used to provide glass removal after resin etchback to reduce wicking and glass plating folds. It can also be added directly into the E-Prep Neutralizer bath to provide frosting of the glass fibers on the hole wall.
Solution makup
Deionized Water Balance
Sulfuric Acid 7% by volume
E-Prep Glass Etch II 50 g/L
 
 


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