PROBIMER® 77-72105 / HARDENER 77-79010

• Two-component-system, semi matt surface
• High resolution and definition
• Wide process windows offer high flexibility
• Excellent chemical, electrical and physical end properties
• Fulfills the requirements of IPC SM-840-C, classes H & T
• Corresponds to the requirements of well-known OEMs
• Excellent adhesion on Probimer 77 solder mask prior or after HAL
• High resistance with aggressive post solder mask metal finishes

• Application as white Solder Mask
• High reflectivity without “yellowing” after multiple reflow process, thermal storage 125℃) and high dose of UV exposure (Light Emitting Diode application)
• Halogen-free-exceeds JPCA Standard
• Low drying temperature level
• No leaching in final finishing chemistries
• High resistance with aggressive post solder mask processes
• High resolution in bar code laser process
• Probimer 77 compatible polymer system in developer
• Excellent adhesion on PR 77 Solder Masks

Room Requirements on Working Environment

In order to reach best results the following room requirements should be respected:

• Room Temperature: 22 ± 2℃ (71.6 ± 35.6 ℉)
• Relative Humidity: 50 ± 5%
• Cleanroom: Class 100’000
• Overpressure Cleanroom + 3 mm WS
• UV filter light

Ink Mixing

• Thoroughly mix the resin component and the hardener component for 10-15 minutes.
• Mixing can be done by hand with a spatula or with gentle mechanical stirring.
• High shear mixing must be avoided in order to prevent entrapment of large amounts of air, which can cause bubbles and poor leveling of the printed coating. Hold the mixed content for at least 30 min for debubbling before use.
• Dilution is generally not required. In specific cases, to avoid coating bubbles between high copper tracks diluent may be added.
• The viscosity is preferably adjusted to 140~160 dpa.s in this case.
• We recommend a maximum dilution of 3% with Dipropyleneglycolmonomethylether (DPM).

Pot Life

At room temperature the ready-to-use mixture has a pot life of 1 day. (Definition of pot life is related to increased dwell time in developer.)

Pre-Cleaning

• For a good adhesion of the lacquer we recommend chemical and/or mechanical pre-cleaning.
• Hold times prior to coating have to be minimized, since oxidation may impair the adhesion of the lacquer.
• Only completely dried boards should be coated, this has to be ensured especially for boards with small holes or blind vias.

Screen Printing

PROBIMER® 77-72105 is applied to printed wiring boards using vertical or horizontal screen printing equipment. The recommended dry film thickness is 20-25μm. Monofilament polyester mesh in the range of 32-43 (mesh/cm) or 80-110 (mesh/inch) .

Flash-off/ Drying

A flash-off time of 10 minutes before drying is recommended. To achieve good performance in resolution, developability of small holes and resistance to finishing processes the coated boards must be dried according to the following parameters:

A maximum hold time of 24 hours between drying and development has to be complied.

Exposure

A hold time prior to exposure is not necessary. The spectral sensitivity is in the range of 350 - 420 nm. The exposure time depends on the parameters for the developing step.

Developing

The areas of unexposed PROBIMER® 77-72105 / 79010 should be developed in a continuous spray developing line. Developing is carried out in a 1.0 % Na2CO3 aqueous alkaline solution.

Inspection and Stripping

• In case of mishandling during exposure, such as mis-registration, boards can be stripped at 60-80 ℃ (140-176 ℉) with 10% NaOH solution.
• After thermal cure the boards could be stripped in 50% KOH at 60-80 ℃ (140-176 ℉) for approx. 60 minutes.

Final Curing

Thermal curing is required to ensure optimal properties in the cured film. It can be done in a standard convection oven.

Legend Inks and Conformal Coatings

• In general, legend inks and conformal coatings exhibit good to excellent adhesion to boards coated with PROBIMER® 77-72105 / 79010.
• However, due to the large variety of available products preliminary trials are strongly recommended.

Production Release Trials

• A variety of flow agents, soldering machines and soldering techniques as well as cleaning processes are used to mount components on circuit boards.
• Adjustment of the processing parameters and design guidelines to ensure optimal use of solder masks leads to the best overall results.
• Users should carry out their own tests prior to release for production runs.

• Probimer lacquers are complex chemical compounds. To ensure that these products exhibit consistent quality in application we recommend storage under the following conditions:
• PROBIMER® 77-72105 in original container at 5-25℃ (41-77 ℉)
• PROBIMER® 79010 in original container at 5-25℃ (41-77 ℉)
• Under ‘EXP’ on the package label, the expiry date is indicated. Within this period the product should be used.